PIC18F2585-I/SPREL - Microchip Technology

PIC18F2585/2680/4585/4680

Data Sheet

28/40/44-Pin

Enhanced Flash Microcontrollers

with ECAN™ Technology, 10-Bit A/D

and nanoWatt Technology

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PIC18F2585/2680/4585/4680

Power Managed Modes:

• Run: CPU on, peripherals on

• Idle: CPU off, peripherals on

• Sleep: CPU off, peripherals off

• Idle mode currents down to 5.8 μA typical

• Sleep mode currents down to 0.1 μA typical

• Timer1 Oscillator: 1.1 μA, 32 kHz, 2V

• Watchdog Timer: 2.1 μA

• Two-Speed Oscillator Start-up

Flexible Oscillator Structure:

• Four Crystal modes, up to 40 MHz

• 4x Phase Lock Loop (PLL) – available for crystal

and internal oscillators

• Two External RC modes, up to 4 MHz

• Two External Clock modes, up to 40 MHz

• Internal oscillator block:

- 8 user selectable frequencies, from 31 kHz to 8 MHz

- Provides a complete range of clock speeds,

from 31 kHz to 32 MHz when used with PLL

- User tunable to compensate for frequency drift

• Secondary oscillator using Timer1 @ 32 kHz

• Fail-Safe Clock Monitor

- Allows for safe shutdown if peripheral clock stops

Special Microcontroller Features:

• C compiler optimized architecture with optional

extended instruction set

• 100,000 erase/write cycle Enhanced Flash

program memory typical

• 1,000,000 erase/write cycle Data EEPROM

memory typical

• Flash/Data EEPROM Retention: > 40 years

• Self-programmable under software control

• Priority levels for interrupts

• 8 x 8 Single Cycle Hardware Multiplier

• Extended Watchdog Timer (WDT):

- Programmable period from 41 ms to 131s

• Single-Supply 5V In-Circuit Serial

Programming™ (ICSP™) via two pins

• In-Circuit Debug (ICD) via two pins

• Wide operating voltage range: 2.0V to 5.5V

Peripheral Highlights:

• High current sink/source 25 mA/25 mA

• Three external interrupts

• One Capture/Compare/PWM (CCP1) module

• Enhanced Capture/Compare/PWM (ECCP1) module

(40/44-pin devices only):

- One, two or four PWM outputs

- Selectable polarity

- Programmable dead time

- Auto-Shutdown and Auto-Restart

• Master Synchronous Serial Port (MSSP) module

supporting 3-wire SPI (all 4 modes) and I2C™

Master and Slave modes

• Enhanced Addressable USART module:

- Supports RS-485, RS-232 and LIN 1.3

- RS-232 operation using internal oscillator

block (no external crystal required)

- Auto-Wake-up on Start bit

- Auto-Baud Detect

• 10-bit, up to 11-channel Analog-to-Digital

Converter module (A/D), up to 100 Ksps

- Auto-acquisition capability

- Conversion available during Sleep

• Dual analog comparators with input multiplexing

ECAN Module Features:

• Message bit rates up to 1 Mbps

• Conforms to CAN 2.0B ACTIVE Specification

• Fully backward compatible with PIC18XXX8 CAN

modules

• Three modes of operation:

- Legacy, Enhanced Legacy, FIFO

• Three dedicated transmit buffers with prioritization

• Two dedicated receive buffers

• Six programmable receive/transmit buffers

• Three full 29-bit acceptance masks

• 16 full 29-bit acceptance filters w/ dynamic association

• DeviceNet™ data byte filter support

• Automatic remote frame handling

• Advanced error management features

Device

Program Memory Data Memory

I/O 10-Bit

A/D (ch)

CCP1/

ECCP1

(PWM)

MSSP

EUSART

Comp. Timers

8/16-bit

Flash

(bytes)

# Single-Word

Instructions

SRAM

(bytes)

EEPROM

(bytes) SPI Master

I2C™

PIC18F2585 48K 24576 3328 1024 28 8 1/0 Y Y 1 0 1/3

PIC18F2680 64K 32768 3328 1024 28 8 1/0 Y Y 1 0 1/3

PIC18F4585 48K 24576 3328 1024 44 11 1/1 Y Y 1 2 1/3

PIC18F4680 64K 32768 3328 1024 40/44 11 1/1 Y Y 1 2 1/3

28/40/44-Pin Enhanced Flash Microcontrollers with

ECAN™ Technology, 10-Bit A/D and nanoWatt Technology

PIC18F2585/2680/4585/4680

Pin Diagrams

RB7/KBI3/PGD

RB6/KBI2/PGC

RB5/KBI1/PGM

RB4/KBI0/AN9

RB3/CANRX

RB2/INT2/CANTX

RB1/INT1/AN8

RB0/INT0/FLT0/AN10

VDD

VSS

RD7/PSP7/P1D

RD6/PSP6/P1C

RD5/PSP5/P1B

RD4/PSP4/ECCP1/P1A

RC7/RX/DT

RC6/TX/CK

RC5/SDO

RC4/SDI/SDA

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

MCLR/VPP/RE3

RA0/AN0/CVREF

RA1/AN1

RA2/AN2/VREF-

RA3/AN3/VREF+

RA4/T0CKI

RA5/AN4/SS/HLVDIN

RE0/RD/AN5

RE1/WR/AN6/C1OUT

RE2/CS/AN7/C2OUT

VDD

VSS

OSC1/CLKI/RA7

OSC2/CLKO/RA6

RC0/T1OSO/T13CKI

RC1/T1OSI

RC2/CCP1

RC3/SCK/SCL

RD0/PSP0/C1IN+

RD1/PSP1/C1IN-

PIC18F4585

40-Pin PDIP

PIC18F4680 PIC18F2585

14 15

MCLR/VPP/RE3

RA0/AN0

RA1/AN1

RA2/AN2/VREF-

RA3/AN3/VREF+

RA4/T0CKI

RA5/AN4/SS/HLVDIN

VSS

OSC1/CLKI/RA7

OSC2/CLKO/RA6

RC0/T1OSO/T13CKI

RC1/T1OSI

RC2/CCP1

RC3/SCK/SCL

RB7/KBI3/PGD

RB6/KBI2/PGC

RB5/KBI1/PGM

RB4/KBI0/AN9

RB3/CANRX

RB2/INT2/CANTX

RB1/INT1/AN8

RB0/INT0/AN10

VDD

VSS

RC7/RX/DT

RC6/TX/CK

RC5/SDO

RC4/SDI/SDA

28-Pin PDIP, SOIC

PIC18F2680

PIC18F2585/2680/4585/4680

Pin Diagrams (Continued)

PIC18F4585

RA3/AN3/VREF+

RA2/AN2/VREF-

RA1/AN1

RA0/AN0/CVREF

MCLR/VPP/RE3

RB7/KBI3/PGD

RB6/KBI2/PGC

RB5/KBI1/PGM

RB4/KBI0/AN9

RC6/TX/CK

RC5/SDO

RC4/SDI/SDA

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RC3/SCK/SCL

RC2/CCP1

RC1/T1OSI

RC0/T1OSO/T13CKI

OSC2/CLKO/RA6

OSC1/CLKI/RA7

VSS

VDD

RE2/CS/AN7/C2OUT

RE1/WR/AN6/C1OUT

RE0/RD/AN5

RA5/AN4/SS/HLVDIN

RA4/T0CKI

RC7/RX/DT

RD4/PSP4/ECCP1/P1A

RD5/PSP5/P1B

RD6/PSP6/P1C

VSS

VDD

RB0/INT0/FLT0/AN10

RB1/INT1/AN8

RB2/INT2/CANTX

RB3/CANRX

44-Pin TQFP

RD7/PSP7/P1D 5

44-Pin QFN

PIC18F4585

RA3/AN3/VREF+

RA2/AN2/VREF-

RA1/AN1

RA0/AN0/CVREF

MCLR/VPP/RE3

RB7/KBI3/PGD

RB6/KBI2/PGC

RB5/KBI1/PGM

RB4/KBI0/AN9

RC6/TX/CK

RC5/SDO

RC4/SDI/SDA

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RC3/SCK/SCL

RC2/CCP1

RC1/T1OSI

RC0/T1OSO/T13CKI

OSC2/CLKO/RA6

OSC1/CLKI/RA7

VSS

AVDD

RE2/CS/AN7/C2OUT

RE1/WR/AN6/C1OUT

RE0/RD/AN5

RA5/AN4/SS/HLVDIN

RA4/T0CKI

RC7/RX/DT

RD5/PSP5/P1B

RD6/PSP6/P1C

VSS

VDD

RB0/INT0/FLT0/AN10

RB1/INT1/AN8

RB2/INT2/CANTX

RB3/CANRX

RD7/PSP7/P1D 5

4AVSS

VDD

AVDD

PIC18F4680

RD4/PSP4/ECCP1/P1A

PIC18F2585/2680/4585/4680
DS39625C-page 4 Preliminary © 2007 Microchip Technology Inc.
Table of Contents
1.0 Device Overview .......................................................................................................................................................................... 7
2.0 Oscillator Configurations ............................................................................................................................................................ 23
3.0 Power Managed Modes ............................................................................................................................................................. 33
4.0 Reset .......................................................................................................................................................................................... 41
5.0 Memory Organization ................................................................................................................................................................. 61
6.0 Flash Program Memory.............................................................................................................................................................. 95
7.0 Data EEPROM Memory ........................................................................................................................................................... 105
8.0 8 x 8 Hardware Multiplier.......................................................................................................................................................... 111
9.0 Interrupts .................................................................................................................................................................................. 113
10.0 I/O Ports ................................................................................................................................................................................... 129
11.0 Timer0 Module ......................................................................................................................................................................... 147
12.0 Timer1 Module ......................................................................................................................................................................... 151
13.0 Timer2 Module ......................................................................................................................................................................... 157
14.0 Timer3 Module ......................................................................................................................................................................... 159
15.0 Capture/Compare/PWM (CCP1) Modules ............................................................................................................................... 163
16.0 Enhanced Capture/Compare/PWM (ECCP1) Module.............................................................................................................. 173
17.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 187
18.0 Enhanced Universal Synchronous Receiver Transmitter (EUSART) ....................................................................................... 227
19.0 10-Bit Analog-to-Digital Converter (A/D) Module ..................................................................................................................... 247
20.0 Comparator Module.................................................................................................................................................................. 257
21.0 Comparator Voltage Reference Module................................................................................................................................... 263
22.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................. 267
23.0 ECAN™ Technology ................................................................................................................................................................ 273
24.0 Special Features of the CPU.................................................................................................................................................... 343
25.0 Instruction Set Summary .......................................................................................................................................................... 361
26.0 Development Support............................................................................................................................................................... 411
27.0 Electrical Characteristics .......................................................................................................................................................... 415
28.0 DC and AC Characteristics Graphs and Tables....................................................................................................................... 451
29.0 Packaging Information.............................................................................................................................................................. 453
Appendix A: Revision History............................................................................................................................................................. 461
Appendix B: Device Differences......................................................................................................................................................... 461
Appendix C: Conversion Considerations ........................................................................................................................................... 462
Appendix D: Migration From Baseline to Enhanced Devices............................................................................................................. 462
Appendix E: Migration from Mid-Range to Enhanced Devices .......................................................................................................... 463
Appendix F: Migration from High-End to Enhanced Devices ............................................................................................................. 463
Index .................................................................................................................................................................................................. 465
The Microchip Web Site ..................................................................................................................................................................... 477
Customer Change Notification Service .............................................................................................................................................. 477
Customer Support .............................................................................................................................................................................. 477
Reader Response .............................................................................................................................................................................. 478
PIC18F2585/2680/4585/4680 Product Identification System ............................................................................................................ 479

PIC18F2585/2680/4585/4680

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PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

1.0 DEVICE OVERVIEW

This document contains device specific information for

the following devices:

• PIC18F2585

• PIC18F2680

• PIC18F4585

• PIC18F4680

This family of devices offers the advantages of all PIC18

microcontrollers – namely, high computational

performance at an economical price – with the addition

of high-endurance, Enhanced Flash program memory.

In addition to these features, the

PIC18F2585/2680/4585/4680 family introduces design

enhancements that make these microcontrollers a

logical choice for many high-performance, power

sensitive applications.

1.1 New Core Features

1.1.1 nanoWatt TECHNOLOGY

All of the devices in the PIC18F2585/2680/4585/4680

family incorporate a range of features that can signifi-

cantly reduce power consumption during operation.

Key items include:

•Alternate Run Modes: By clocking the controller

from the Timer1 source or the internal oscillator

block, power consumption during code execution

can be reduced by as much as 90%.

•Multiple Idle Modes: The controller can also run

with its CPU core disabled but the peripherals still

active. In these states, power consumption can be

reduced even further, to as little as 4% of normal

operation requirements.

•On-the-fly Mode Switching: The power

managed modes are invoked by user code during

operation, allowing the user to incorporate

power-saving ideas into their application’s

software design.

•Lower Consumption in Key Modules: The

power requirements for both Timer1 and the

Watchdog Timer have been reduced by up to

80%, with typical values of 1.1 and 2.1 μA,

respectively.

•Extended Instruction Set: In addition to the

standard 75 instructions of the PIC18 instruction

set, PIC18F2585/2680/4585/4680 devices also

provide an optional extension to the core CPU

functionality. The added features include eight

additional instructions that augment indirect and

indexed addressing operations and the

implementation of Indexed Literal Offset

Addressing mode for many of the standard PIC18

instructions.

1.1.2 MULTIPLE OSCILLATOR OPTIONS

AND FEATURES

All of the devices in the PIC18F2585/2680/4585/4680

family offer ten different oscillator options, allowing

users a wide range of choices in developing application

hardware. These include:

• Four Crystal modes, using crystals or ceramic

resonators

• Two External Clock modes, offering the option of

using two pins (oscillator input and a divide-by-4

clock output) or one pin (oscillator input, with the

second pin reassigned as general I/O)

• Two External RC Oscillator modes with the same

pin options as the External Clock modes

• An internal oscillator block which provides an

8 MHz clock (±2% accuracy) and an INTRC

source (approximately 31 kHz, stable over

temperature and VDD), as well as a range of

6 user selectable clock frequencies, between

125 kHz to 4 MHz, for a total of 8 clock

frequencies. This option frees the two oscillator

pins for use as additional general purpose I/O.

• A Phase Lock Loop (PLL) frequency multiplier,

available to both the high-speed crystal and

internal oscillator modes, which allows clock

speeds of up to 40 MHz. Used with the internal

oscillator, the PLL gives users a complete

selection of clock speeds, from 31 kHz to

32 MHz – all without using an external crystal or

clock circuit.

Besides its availability as a clock source, the internal

oscillator block provides a stable reference source that

gives the family additional features for robust

operation:

•Fail-Safe Clock Monitor: This option constantly

monitors the main clock source against a refer-

ence signal provided by the internal oscillator. If a

clock failure occurs, the controller is switched to

the internal oscillator block, allowing for continued

low-speed operation or a safe application

shutdown.

•Two-Speed Start-up: This option allows the

internal oscillator to serve as the clock source

from Power-on Reset, or wake-up from Sleep

mode, until the primary clock source is available.

PIC18F2585/2680/4585/4680

1.2 Other Special Features

•Memory Endurance: The Enhanced Flash cells

for both program memory and data EEPROM are

rated to last for many thousands of erase/write

cycles – up to 100,000 for program memory and

1,000,000 for EEPROM. Data retention without

refresh is conservatively estimated to be greater

than 40 years.

•Self-programmability: These devices can write

to their own program memory spaces under inter-

nal software control. By using a bootloader rou-

tine located in the protected Boot Block at the top

of program memory, it becomes possible to create

an application that can update itself in the field.

•Extended Instruction Set: The

PIC18F2585/2680/4585/4680 family introduces

an optional extension to the PIC18 instruction set,

which adds 8 new instructions and an Indexed

Addressing mode. This extension, enabled as a

device configuration option, has been specifically

designed to optimize re-entrant application code

originally developed in high-level languages, such

as C.

•Enhanced CCP1 module: In PWM mode, this

module provides 1, 2 or 4 modulated outputs for

controlling half-bridge and full-bridge drivers.

Other features include Auto-Shutdown, for

disabling PWM outputs on interrupt or other select

conditions and Auto-Restart, to reactivate outputs

once the condition has cleared.

•Enhanced Addressable USART: This serial

communication module is capable of standard

RS-232 operation and provides support for the LIN

bus protocol. Other enhancements include

automatic baud rate detection and a 16-bit Baud

Rate Generator for improved resolution. When the

microcontroller is using the internal oscillator

block, the EUSART provides stable operation for

applications that talk to the outside world without

using an external crystal (or its accompanying

power requirement).

•10-bit A/D Converter: This module incorporates

programmable acquisition time, allowing for a

channel to be selected and a conversion to be

initiated without waiting for a sampling period and

thus, reduce code overhead.

•Extended Watchdog Timer (WDT): This

enhanced version incorporates a 16-bit prescaler,

allowing a time-out range from 4 ms to over

131 seconds, that is stable across operating

voltage and temperature.

1.3 Details on Individual Family

Members

Devices in the PIC18F2585/2680/4585/4680 family are

available in 28-pin (PIC18F2X8X) and 40/44-pin

(PIC18F4X8X) packages. Block diagrams for the two

groups are shown in Figure 1-1 and Figure 1-2.

The devices are differentiated from each other in six

ways:

1. Flash program memory (48 Kbytes for

PIC18FX585 devices, 64 Kbytes for

PIC18FX680).

2. A/D channels (8 for PIC18F2X8X devices, 11 for

PIC18F4X8X devices).

3. I/O ports (3 bidirectional ports and 1 input only

port on PIC18F2X8X devices, 5 bidirectional

ports on PIC18F4X8X devices).

4. CCP1 and Enhanced CCP1 implementation

(PIC18F2X8X devices have 1 standard CCP1

module, PIC18F4X8X devices have one

standard CCP1 module and one ECCP1

module).

5. Parallel Slave Port (present only on

PIC18F4X8X devices).

6. PIC18F4X8X devices provide two comparators.

All other features for devices in this family are identical.

These are summarized in Table 1-1.

The pinouts for all devices are listed in Table 1-2 and

Table 1-3.

Like all Microchip PIC18 devices, members of the

PIC18F2585/2680/4585/4680 family are available as

both standard and low-voltage devices. Standard

devices with Enhanced Flash memory, designated with

an “F” in the part number (such as PIC18F2585),

accommodate an operating VDD range of 4.2V to 5.5V.

Low-voltage parts, designated by “LF” (such as

PIC18LF2585), function over an extended VDD range

of 2.0V to 5.5V.

PIC18F2585/2680/4585/4680

TABLE 1-1: DEVICE FEATURES

Features PIC18F2585 PIC18F2680 PIC18F4585 PIC18F4680

Operating Frequency DC – 40 MHz DC – 40 MHz DC – 40 MHz DC – 40 MHz

Program Memory (Bytes) 49152 65536 49152 65536

Program Memory (Instructions) 24576 32768 24576 32768

Data Memory (Bytes) 3328 3328 3328 3328

Data EEPROM Memory (Bytes) 1024 1024 1024 1024

Interrupt Sources 19 19 20 20

I/O Ports Ports A, B, C, (E) Ports A, B, C, (E) Ports A, B, C, D, E Ports A, B, C, D, E

Timers 4 4 4 4

Capture/Compare/PWM Modules 1 1 1 1

Enhanced Capture/

Compare/PWM Modules

0011

ECAN Module 1 1 1 1

Serial Communications MSSP,

Enhanced USART

MSSP,

Enhanced USART

MSSP,

Enhanced USART

MSSP,

Enhanced USART

Parallel Communications (PSP) No No Yes Yes

10-bit Analog-to-Digital Module 8 Input Channels 8 Input Channels 11 Input Channels 11 Input Channels

Comparators 0 0 2 2

Resets (and Delays) POR, BOR,

RESET Instruction,

Stack Full,

Stack Underflow

(PWRT, OST),

MCLR (optional),

WDT

POR, BOR,

RESET Instruction,

Stack Full,

Stack Underflow

(PWRT, OST),

MCLR (optional),

WDT

POR, BOR,

RESET Instruction,

Stack Full,

Stack Underflow

(PWRT, OST),

MCLR (optional),

WDT

POR, BOR,

RESET Instruction,

Stack Full,

Stack Underflow

(PWRT, OST),

MCLR (optional),

WDT

Programmable High/Low-Voltage

Detect

Yes Yes Yes Yes

Programmable Brown-out Reset Yes Yes Yes Yes

Instruction Set 75 Instructions;

83 with Extended

Instruction Set

enabled

75 Instructions;

83 with Extended

Instruction Set

enabled

75 Instructions;

83 with Extended

Instruction Set

enabled

75 Instructions;

83 with Extended

Instruction Set

enabled

Packages 28-pin PDIP

28-pin SOIC

28-pin PDIP

28-pin SOIC

40-pin PDIP

44-pin QFN

44-pin TQFP

40-pin PDIP

44-pin QFN

44-pin TQFP

PIC18F2585/2680/4585/4680

FIGURE 1-1: PIC18F2585/2680 (28-PIN) BLOCK DIAGRAM

Instruction

Decode &

Control

PORTA

PORTB

PORTC

RA4/T0CKI

RA5/AN4/SS/HLVDIN

RB0/INT0/AN10

RC0/T1OSO/T13CKI

RC1/T1OSI

RC2/CCP1

RC3/SCK/SCL

RC4/SDI/SDA

RC5/SDO

RC6/TX/CK

RC7/RX/DT

RA3/AN3/VREF+

RA2/AN2/VREF-

RA1/AN1

RA0/AN0

RB1/INT1/AN8

Data Latch

Data Memory

(3.9 Kbytes)

Address Latch

Data Address<12>

Access

BSR

PCH PCL

PCLATH

31 Level Stack

Program Counter

PRODLPRODH

8 x 8 Multiply

ALU<8>

Address Latch

Program Memory

(48/64 Kbytes)

Data Latch

Table Pointer<21>

inc/dec logic

Data Bus<8>

Table Latch

ROM Latch

RB2/INT2/CANTX

RB3/CANRX

PCLATU

PCU

PORTE

MCLR/VPP/RE3(1)

OSC2/CLKO/RA6

Note 1: RE3 is multiplexed with MCLR and is only available when the MCLR Resets are disabled.

2: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O.

Refer to Section 2.0 “Oscillator Configurations” for additional information.

RB4/KBI0/AN9

RB5/KBI1/PGM

RB6/KBI2/PGC

RB7/KBI3/PGD

EUSARTComparator MSSP 10-bit

ADC

Timer2Timer1 Timer3Timer0

ECCP1

HLVD

CCP1

BOR Data

EEPROM

Instruction Bus <16>

STKPTR Bank

State Machine

Control Signals

Power-up

Timer

Oscillator

Start-up Timer

Power-on

Reset

Watchdog

Timer

OSC1(2)

OSC2(2)

VDD,

Brown-out

Reset

Internal

Oscillator

Fail-Safe

Clock Monitor

Reference

Band Gap

VSS

MCLR(1)

Block

INTRC

Oscillator

8 MHz

Oscillator

Single-Supply

Programming

In-Circuit

Debugger

T1OSI

T1OSO

OSC1/CLKI/RA7

ECAN

BITOP

FSR0

FSR1

FSR2

inc/dec

Address

Decode

logic

PIC18F2585/2680/4585/4680

FIGURE 1-2: PIC18F4585/4680 (40/44-PIN) BLOCK DIAGRAM

Instruction

Decode &

Control

Data Latch

Data Memory

(3.9 Kbytes)

Address Latch

Data Address<12>

Access

BSR

PCH PCL

PCLATH

31 Level Stack

Program Counter

PRODLPRODH

8 x 8 Multiply

BITOP

ALU<8>

Address Latch

Program Memory

(48/64 Kbytes)

Data Latch

Table Pointer<21>

inc/dec logic

Data Bus<8>

Table Latch

ROM Latch

PORTD

RD0/PSP0

PCLATU

PCU

PORTE

MCLR/VPP/RE3(1)

RE2/CS/AN7/C2OUT

RE0/RD/AN5

RE1/WR/AN6/C1OUT

Note 1: RE3 is multiplexed with MCLR and is only available when the MCLR Resets are disabled.

2: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O.

Refer to Section 2.0 “Oscillator Configurations” for additional information.

/C1IN+

EUSARTComparator MSSP 10-bit

ADC

Timer2Timer1 Timer3Timer0

CCP1

HLVD

ECCP1

BOR Data

EEPROM

Instruction Bus <16>

STKPTR Bank

State Machine

Control Signals

Power-up

Timer

Oscillator

Start-up Timer

Power-on

Reset

Watchdog

Timer

OSC1(2)

OSC2(2)

VDD,

Brown-out

Reset

Internal

Oscillator

Fail-Safe

Clock Monitor

Reference

Band Gap

VSS

MCLR(1)

Block

INTRC

Oscillator

8 MHz

Oscillator

Single-Supply

Programming

In-Circuit

Debugger

T1OSI

T1OSO

RD1/PSP1/C1IN-

RD2/PSP2/C2IN+

RD3/PSP3/C2IN-

PORTA

PORTB

PORTC

RA4/T0CKI

RA5/AN4/SS/HLVDIN

RB0/INT0/FLT0/AN10

RC0/T1OSO/T13CKI

RC1/T1OSI

RC2/CCP1

RC3/SCK/SCL

RC4/SDI/SDA

RC5/SDO

RC6/TX/CK

RC7/RX/DT

RA3/AN3/VREF+

RA2/AN2/VREF-

RA1/AN1

RA0/AN0/CVREF

RB1/INT1/AN8

RB2/INT2/CANTX

RB3/CANRX

OSC2/CLKO/RA6

RB4/KBI0/AN9

RB5/KBI1/PGM

RB6/KBI2/PGC

RB7/KBI3/PGD

OSC1/CLKI/RA7

ECAN

FSR0

FSR1

FSR2

inc/dec

Address

Decode

logic

RD4/PSP4/ECCP1/P1A

RD5/PSP5/P1B

RD6/PSP6/P1C

RD7/PSP7/P1D

PIC18F2585/2680/4585/4680

TABLE 1-2: PIC18F2585/2680 PINOUT I/O DESCRIPTIONS

Pin Name

Number Pin

Type

Buffer

Type Description

PDIP,

SOIC

MCLR/VPP/RE3

MCLR

VPP

RE3

Master Clear (input) or programming voltage (input).

Master Clear (Reset) input. This pin is an active-low

Reset to the device.

Programming voltage input.

Digital input.

OSC1/CLKI/RA7

OSC1

CLKI

RA7

I/O

CMOS

TTL

Oscillator crystal or external clock input.

Oscillator crystal input or external clock source input.

ST buffer when configured in RC mode; CMOS otherwise.

External clock source input. Always associated with pin

function OSC1. (See related OSC1/CLKI, OSC2/CLKO pins.)

General purpose I/O pin.

OSC2/CLKO/RA6

OSC2

CLKO

RA6

I/O

—

TTL

Oscillator crystal or clock output.

Oscillator crystal output. Connects to crystal or resonator in

Crystal Oscillator mode.

In RC mode, OSC2 pin outputs CLKO which has 1/4 the

frequency of OSC1 and denotes the instruction cycle rate.

General purpose I/O pin.

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTA is a bidirectional I/O port.

RA0/AN0

RA0

AN0

I/O

TTL

Analog

Digital I/O.

Analog input 0.

RA1/AN1

RA1

AN1

I/O

TTL

Analog

Digital I/O.

Analog input 1.

RA2/AN2/VREF-

RA2

AN2

VREF-

I/O

TTL

Analog

Digital I/O.

Analog input 2.

A/D reference voltage (low) input.

RA3/AN3/VREF+

RA3

AN3

VREF+

I/O

TTL

Analog

Digital I/O.

Analog input 3.

A/D reference voltage (high) input.

RA4/T0CKI

RA4

T0CKI

I/O

TTL

Digital I/O.

Timer0 external clock input.

RA5/AN4/SS/HLVDIN

RA5

AN4

HLVDIN

I/O

TTL

Analog

TTL

Analog

Digital I/O.

Analog input 4.

SPI slave select input.

High/Low-Voltage Detect input.

RA6 See the OSC2/CLKO/RA6 pin.

RA7 See the OSC1/CLKI/RA7 pin.

TABLE 1-2: PIC18F2585/2680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name

Number Pin

Type

Buffer

Type Description

PDIP,

SOIC

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTB is a bidirectional I/O port. PORTB can be software

programmed for internal weak pull-ups on all inputs.

RB0/INT0/AN10

RB0

INT0

AN10

I/O

TTL

Analog

Digital I/O.

External interrupt 0.

Analog input 10.

RB1/INT1/AN8

RB1

INT1

AN8

I/O

TTL

Analog

Digital I/O.

External interrupt 1.

Analog input 8.

RB2/INT2/CANTX

RB2

INT2

CANTX

I/O

TTL

Digital I/O.

External interrupt 2.

CAN bus TX.

RB3/CANRX

RB3

CANRX

I/O

TTL

Digital I/O.

CAN bus RX.

RB4/KBI0/AN9

RB4

KBI0

AN9

I/O

TTL

Analog

Digital I/O.

Interrupt-on-change pin.

Analog input 9.

RB5/KBI1/PGM

RB5

KBI1

PGM

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

Low-Voltage ICSP™ Programming enable pin.

RB6/KBI2/PGC

RB6

KBI2

PGC

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

In-Circuit Debugger and ICSP programming clock pin.

RB7/KBI3/PGD

RB7

KBI3

PGD

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

In-Circuit Debugger and ICSP programming data pin.

TABLE 1-2: PIC18F2585/2680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name

Number Pin

Type

Buffer

Type Description

PDIP,

SOIC

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTC is a bidirectional I/O port.

RC0/T1OSO/T13CKI

RC0

T1OSO

T13CKI

I/O

—

Digital I/O.

Timer1 oscillator output.

Timer1/Timer3 external clock input.

RC1/T1OSI

RC1

T1OSI

I/O

CMOS

Digital I/O.

Timer1 oscillator input.

RC2/CCP1

RC2

CCP1

I/O

Digital I/O.

Capture1 input/Compare1 output/PWM1 output.

RC3/SCK/SCL

RC3

SCK

SCL

I/O

Digital I/O.

Synchronous serial clock input/output for SPI mode.

Synchronous serial clock input/output for I2C™ mode.

RC4/SDI/SDA

RC4

SDI

SDA

I/O

Digital I/O.

SPI data in.

I2C data I/O.

RC5/SDO

RC5

SDO

I/O

—

Digital I/O.

SPI data out.

RC6/TX/CK

RC6

I/O

—

Digital I/O.

EUSART asynchronous transmit.

EUSART synchronous clock (see related RX/DT).

RC7/RX/DT

RC7

I/O

Digital I/O.

EUSART asynchronous receive.

EUSART synchronous data (see related TX/CK).

RE3 — — — See MCLR/VPP/RE3 pin.

VSS 8, 19 P — Ground reference for logic and I/O pins.

VDD 20 P — Positive supply for logic and I/O pins.

TABLE 1-2: PIC18F2585/2680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name

Number Pin

Type

Buffer

Type Description

PDIP,

SOIC

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

MCLR/VPP/RE3

MCLR

VPP

RE3

11818

Master Clear (input) or programming voltage (input).

Master Clear (Reset) input. This pin is an

active-low Reset to the device.

Programming voltage input.

Digital input.

OSC1/CLKI/RA7

OSC1

CLKI

RA7

13 32 30

I/O

CMOS

TTL

Oscillator crystal or external clock input.

Oscillator crystal input or external clock source input.

ST buffer when configured in RC mode;

CMOS otherwise.

External clock source input. Always associated with

pin function OSC1. (See related OSC1/CLKI,

OSC2/CLKO pins.)

General purpose I/O pin.

OSC2/CLKO/RA6

OSC2

CLKO

RA6

14 33 31

I/O

—

TTL

Oscillator crystal or clock output.

Oscillator crystal output. Connects to crystal or

resonator in Crystal Oscillator mode.

In RC mode, OSC2 pin outputs CLKO which has 1/4

the frequency of OSC1 and denotes the instruction

cycle rate.

General purpose I/O pin.

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTA is a bidirectional I/O port.

RA0/AN0/CVREF

RA0

AN0

CVREF

21919

I/O

TTL

Analog

Digital I/O.

Analog input 0.

Analog comparator reference output.

RA1/AN1

RA1

AN1

32020

I/O

TTL

Analog

Digital I/O.

Analog input 1.

RA2/AN2/VREF-

RA2

AN2

VREF-

42121

I/O

TTL

Analog

Digital I/O.

Analog input 2.

A/D reference voltage (low) input.

RA3/AN3/VREF+

RA3

AN3

VREF+

52222

I/O

TTL

Analog

Digital I/O.

Analog input 3.

A/D reference voltage (high) input.

RA4/T0CKI

RA4

T0CKI

62323

I/O

TTL

Digital I/O.

Timer0 external clock input.

RA5/AN4/SS/HLVDIN

RA5

AN4

HLVDIN

72424

I/O

TTL

Analog

TTL

Analog

Digital I/O.

Analog input 4.

SPI slave select input.

High/Low-Voltage Detect input.

RA6 See the OSC2/CLKO/RA6 pin.

RA7 See the OSC1/CLKI/RA7 pin.

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTB is a bidirectional I/O port. PORTB can be

software programmed for internal weak pull-ups on all

inputs.

RB0/INT0/FLT0/AN10

RB0

INT0

FLT0

AN10

33 9 8

I/O

TTL

Analog

Digital I/O.

External interrupt 0.

Enhanced PWM Fault input (ECCP1 module).

Analog input 10.

RB1/INT1/AN8

RB1

INT1

AN8

34 10 9

I/O

TTL

Analog

Digital I/O.

External interrupt 1.

Analog input 8.

RB2/INT2/CANTX

RB2

INT2

CANTX

35 11 10

I/O

TTL

Digital I/O.

External interrupt 2.

CAN bus TX.

RB3/CANRX

RB3

CANRX

36 12 11

I/O

TTL

Digital I/O.

CAN bus RX.

RB4/KBI0/AN9

RB4

KBI0

AN9

37 14 14

I/O

TTL

Analog

Digital I/O.

Interrupt-on-change pin.

Analog input 9.

RB5/KBI1/PGM

RB5

KBI1

PGM

38 15 15

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

Low-Voltage ICSP™ Programming enable pin.

RB6/KBI2/PGC

RB6

KBI2

PGC

39 16 16

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

In-Circuit Debugger and ICSP programming

clock pin.

RB7/KBI3/PGD

RB7

KBI3

PGD

40 17 17

I/O

TTL

Digital I/O.

Interrupt-on-change pin.

In-Circuit Debugger and ICSP programming

data pin.

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTC is a bidirectional I/O port.

RC0/T1OSO/T13CKI

RC0

T1OSO

T13CKI

15 34 32

I/O

—

Digital I/O.

Timer1 oscillator output.

Timer1/Timer3 external clock input.

RC1/T1OSI

RC1

T1OSI

16 35 35

I/O

CMOS

Digital I/O.

Timer1 oscillator input.

RC2/CCP1

RC2

CCP1

17 36 36

I/O

Digital I/O.

Capture1 input/Compare1 output/PWM1 output.

RC3/SCK/SCL

RC3

SCK

SCL

18 37 37

I/O

Digital I/O.

Synchronous serial clock input/output for

SPI mode.

Synchronous serial clock input/output for

I2C™ mode.

RC4/SDI/SDA

RC4

SDI

SDA

23 42 42

I/O

Digital I/O.

SPI data in.

I2C data I/O.

RC5/SDO

RC5

SDO

24 43 43

I/O

—

Digital I/O.

SPI data out.

RC6/TX/CK

RC6

25 44 44

I/O

—

Digital I/O.

EUSART asynchronous transmit.

EUSART synchronous clock (see related RX/DT).

RC7/RX/DT

RC7

26 1 1

I/O

Digital I/O.

EUSART asynchronous receive.

EUSART synchronous data (see related TX/CK).

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTD is a bidirectional I/O port or a Parallel Slave

Port (PSP) for interfacing to a microprocessor port.

These pins have TTL input buffers when PSP module

is enabled.

RD0/PSP0/C1IN+

RD0

PSP0

C1IN+

19 38 38

I/O

TTL

Analog

Digital I/O.

Parallel Slave Port data.

Comparator 1 input (+).

RD1/PSP1/C1IN-

RD1

PSP1

C1IN-

20 39 39

I/O

TTL

Analog

Digital I/O.

Parallel Slave Port data.

Comparator 1 input (-)

RD2/PSP2/C2IN+

RD2

PSP2

C2IN+

21 40 40

I/O

TTL

Analog

Digital I/O.

Parallel Slave Port data.

Comparator 2 input (+).

RD3/PSP3/C2IN-

RD3

PSP3

C2IN-

22 41 41

I/O

TTL

Analog

Digital I/O.

Parallel Slave Port data.

Comparator 2 input (-).

RD4/PSP4/ECCP1/

P1A

RD4

PSP4

ECCP1

P1A

27 2 2

I/O

TTL

Digital I/O.

Parallel Slave Port data.

Capture2 input/Compare2 output/PWM2 output.

ECCP1 PWM output A.

RD5/PSP5/P1B

RD5

PSP5

P1B

28 3 3

I/O

TTL

Digital I/O.

Parallel Slave Port data.

ECCP1 PWM output B.

RD6/PSP6/P1C

RD6

PSP6

P1C

29 4 4

I/O

TTL

Digital I/O.

Parallel Slave Port data.

ECCP1 PWM output C.

RD7/PSP7/P1D

RD7

PSP7

P1D

30 5 5

I/O

TTL

Digital I/O.

Parallel Slave Port data.

ECCP1 PWM output D.

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

PORTE is a bidirectional I/O port.

RE0/RD/AN5

RE0

AN5

82525

I/O

TTL

Analog

Digital I/O.

Read control for Parallel Slave Port (see also WR

and CS pins).

Analog input 5.

RE1/WR/AN6/C1OUT

RE1

AN6

C1OUT

92626

I/O

TTL

Analog

TTL

Digital I/O.

Write control for Parallel Slave Port (see CS

and RD pins).

Analog input 6.

Comparator 1 output.

RE2/CS/AN7/C2OUT

RE2

AN7

C2OUT

10 27 27

I/O

TTL

Analog

TTL

Digital I/O.

Chip select control for Parallel Slave Port (see

related RD and WR).

Analog input 7.

Comparator 2 output.

RE3 — — — — — See MCLR/VPP/RE3 pin.

VSS 12,

6, 30,

6, 29 P — Ground reference for logic and I/O pins.

VDD 11, 32 7, 8,

28, 29

7, 28 P — Positive supply for logic and I/O pins.

NC — 13 12, 13,

33, 34

— — No connect.

TABLE 1-3: PIC18F4585/4680 PINOUT I/O DESCRIPTIONS (CONTINUED)

Pin Name Pin Number Pin

Type

Buffer

Type Description

PDIP QFN TQFP

Legend: TTL = TTL compatible input CMOS = CMOS compatible input or output

ST = Schmitt Trigger input with CMOS levels I = Input

O = Output P = Power

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

2.0 OSCILLATOR

CONFIGURATIONS

2.1 Oscillator Types

PIC18F2585/2680/4585/4680 devices can be operated

in ten different oscillator modes. The user can program

the Configuration bits, FOSC3:FOSC0, in Configuration

1. LP Low-Power Crystal

2. XT Crystal/Resonator

3. HS High-Speed Crystal/Resonator

4. HSPLL High-Speed Crystal/Resonator

with PLL enabled

5. RC External Resistor/Capacitor with

FOSC/4 output on RA6

6. RCIO External Resistor/Capacitor with I/O

on RA6

7. INTIO1 Internal Oscillator with FOSC/4 output

on RA6 and I/O on RA7

8. INTIO2 Internal Oscillator with I/O on RA6

and RA7

9. EC External Clock with FOSC/4 output

10. ECIO External Clock with I/O on RA6

2.2 Crystal Oscillator/Ceramic

Resonators

In XT, LP, HS or HSPLL Oscillator modes, a crystal or

ceramic resonator is connected to the OSC1 and

OSC2 pins to establish oscillation. Figure 2-1 shows

the pin connections.

The oscillator design requires the use of a parallel cut

crystal.

FIGURE 2-1: CRYSTAL/CERAMIC

RESONATOR OPERATION

(XT, LP, HS OR HSPLL

CONFIGURATION)

TABLE 2-1: CAPACITOR SELECTION FOR

CERAMIC RESONATORS

Note: Use of a series cut crystal may give a

frequency out of the crystal manufacturer’s

specifications.

Typical Capacitor Values Used:

Mode Freq OSC1 OSC2

XT 455 kHz

2.0 MHz

4.0 MHz

56 pF

47 pF

33 pF

56 pF

47 pF

33 pF

HS 8.0 MHz

16.0 MHz

27 pF

22 pF

27 pF

22 pF

Capacitor values are for design guidance only.

These capacitors were tested with the resonators

listed below for basic start-up and operation. These

values are not optimized.

Different capacitor values may be required to produce

acceptable oscillator operation. The user should test

the performance of the oscillator over the expected

VDD and temperature range for the application.

See the notes on page 24 for additional information.

Resonators Used:

455 kHz 4.0 MHz

2.0 MHz 8.0 MHz

16.0 MHz

Note: When using resonators with frequencies

above 3.5 MHz, the use of HS mode,

rather than XT mode, is recommended.

HS mode may be used at any VDD for

which the controller is rated. If HS is

selected, it is possible that the gain of the

oscillator will overdrive the resonator.

Therefore, a series resistor should be

placed between the OSC2 pin and the

resonator. As a good starting point, the

recommended value of RS is 330Ω.

Note 1: See Table 2-1 and Table 2-2 for initial values of

C1 and C2.

2: A series resistor (RS) may be required for AT

strip cut crystals.

3: RF varies with the oscillator mode chosen.

C1(1)

C2(1)

XTAL

OSC2

OSC1

RF(3)

Sleep

Logic

PIC18FXXXX

RS(2)

Internal

PIC18F2585/2680/4585/4680

TABLE 2-2: CAPACITOR SELECTION FOR

CRYSTAL OSCILLATOR

An external clock source may also be connected to the

OSC1 pin in the HS mode, as shown in Figure 2-2.

FIGURE 2-2: EXTERNAL CLOCK

INPUT OPERATION

(HS OSCILLATOR

CONFIGURATION)

2.3 External Clock Input

The EC and ECIO Oscillator modes require an external

clock source to be connected to the OSC1 pin. There is

no oscillator start-up time required after a Power-on

Reset or after an exit from Sleep mode.

In the EC Oscillator mode, the oscillator frequency

divided by 4 is available on the OSC2 pin. This signal

may be used for test purposes or to synchronize other

logic. Figure 2-3 shows the pin connections for the EC

Oscillator mode.

FIGURE 2-3: EXTERNAL CLOCK

INPUT OPERATION

(EC CONFIGURATION)

The ECIO Oscillator mode functions like the EC mode,

except that the OSC2 pin becomes an additional

general purpose I/O pin. The I/O pin becomes bit 6 of

PORTA (RA6). Figure 2-4 shows the pin connections

for the ECIO Oscillator mode.

FIGURE 2-4: EXTERNAL CLOCK

INPUT OPERATION

(ECIO CONFIGURATION)

Osc Type Crystal

Freq

Typical Capacitor Values

Tested:

C1 C2

LP 32 kHz 33 pF 33 pF

200 kHz 15 pF 15 pF

XT 1 MHz 33 pF 33 pF

4 MHz 27 pF 27 pF

HS 4 MHz 27 pF 27 pF

8 MHz 22 pF 22 pF

20 MHz 15 pF 15 pF

Capacitor values are for design guidance only.

These capacitors were tested with the crystals listed

below for basic start-up and operation. These values

are not optimized.

Different capacitor values may be required to produce

acceptable oscillator operation. The user should test

the performance of the oscillator over the expected

VDD and temperature range for the application.

See the notes following this table for additional

information.

Crystals Used:

32 kHz 4 MHz

200 kHz 8 MHz

1 MHz 20 MHz

Note 1: Higher capacitance increases the stability

of the oscillator but also increases the

start-up time.

2: When operating below 3V VDD, or when

using certain ceramic resonators at any

voltage, it may be necessary to use the

HS mode or switch to a crystal oscillator.

3: Since each resonator/crystal has its own

characteristics, the user should consult

the resonator/crystal manufacturer for

appropriate values of external

components.

4: Rs may be required to avoid overdriving

crystals with low drive level specification.

5: Always verify oscillator performance over

the VDD and temperature range that is

expected for the application.

OSC1

OSC2

Open

Clock from

Ext. System PIC18FXXXX

(HS Mode)

OSC1/CLKI

OSC2/CLKO

FOSC/4

Clock from

Ext. System PIC18FXXXX

OSC1/CLKI

I/O (OSC2)

RA6

Clock from

Ext. System PIC18FXXXX

PIC18F2585/2680/4585/4680

2.4 RC Oscillator

For timing insensitive applications, the “RC” and

“RCIO” device options offer additional cost savings.

The actual oscillator frequency is a function of several

factors:

• supply voltage

• values of the external resistor (REXT) and

capacitor (CEXT)

• operating temperature

Given the same device, operating voltage and tempera-

ture and component values, there will also be unit-to-unit

frequency variations. These are due to factors such as:

• normal manufacturing variation

• difference in lead frame capacitance between

package types (especially for low CEXT values)

• variations within the tolerance of limits of REXT

and CEXT

In the RC Oscillator mode, the oscillator frequency

divided by 4 is available on the OSC2 pin. This signal

may be used for test purposes or to synchronize other

logic. Figure 2-5 shows how the R/C combination is

connected.

FIGURE 2-5: RC OSCILLATOR MODE

The RCIO Oscillator mode (Figure 2-6) functions like

the RC mode, except that the OSC2 pin becomes an

additional general purpose I/O pin. The I/O pin

becomes bit 6 of PORTA (RA6).

FIGURE 2-6: RCIO OSCILLATOR MODE

2.5 PLL Frequency Multiplier

A Phase Locked Loop (PLL) circuit is provided as an

option for users who wish to use a lower frequency

oscillator circuit or to clock the device up to its highest

rated frequency from a crystal oscillator. This may be

useful for customers who are concerned with EMI due

to high-frequency crystals or users who require higher

clock speeds from an internal oscillator.

2.5.1 HSPLL OSCILLATOR MODE

The HSPLL mode makes use of the HS mode oscillator

for frequencies up to 10 MHz. A PLL then multiplies the

oscillator output frequency by 4 to produce an internal

clock frequency up to 40 MHz.

The PLL is only available to the crystal oscillator when

the FOSC3:FOSC0 Configuration bits are programmed

for HSPLL mode (= 0110).

FIGURE 2-7: PLL BLOCK DIAGRAM

(HS MODE)

2.5.2 PLL AND INTOSC

The PLL is also available to the internal oscillator block

in selected oscillator modes. In this configuration, the

PLL is enabled in software and generates a clock

output of up to 32 MHz. The operation of INTOSC with

the PLL is described in Section 2.6.4 “PLL in INTOSC

Modes”.

OSC2/CLKO

CEXT

REXT

PIC18FXXXX

OSC1

FOSC/4

Internal

Clock

VDD

VSS

Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ

CEXT > 20 pF

CEXT

REXT

PIC18FXXXX

OSC1 Internal

Clock

VDD

VSS

Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ

CEXT > 20 pF

I/O (OSC2)

RA6

MUX

VCO

Loop

Filter

Crystal

Osc

OSC2

OSC1

PLL Enable

FIN

FOUT

SYSCLK

Phase

Comparator

HS Osc Enable

÷4

(from Configuration Register 1H)

HS Mode

PIC18F2585/2680/4585/4680
DS39625C-page 26 Preliminary © 2007 Microchip Technology Inc.
2.6 Internal Oscillator Block
The PIC18F2585/2680/4585/4680 devices include an
internal oscillator block which generates two different
clock signals; either can be used as the microcontroller’s
clock source. This may eliminate the need for external
oscillator circuits on the OSC1 and/or OSC2 pins.
The main output (INTOSC) is an 8 MHz clock source,
which can be used to directly drive the device clock. It
also drives a postscaler, which can provide a range of
clock frequencies from 31 kHz to 4 MHz. The INTOSC
output is enabled when a clock frequency from 125 kHz
to 8 MHz is selected.
The other clock source is the internal RC oscillator
(INTRC), which provides a nominal 31 kHz output.
INTRC is enabled if it is selected as the device clock
source; it is also enabled automatically when any of the
following are enabled: 
• Power-up Timer
• Fail-Safe Clock Monitor
• Watchdog Timer
• Two-Speed Start-up
These features are discussed in greater detail in
Section 24.0 “Special Features of the CPU”.
The clock source frequency (INTOSC direct, INTRC
direct or INTOSC postscaler) is selected by configuring
the IRCF bits of the OSCCON register (Register 2-2).
2.6.1 INTIO MODES
Using the internal oscillator as the clock source
eliminates the need for up to two external oscillator
pins, which can then be used for digital I/O. Two distinct
configurations are available:
• In INTIO1 mode, the OSC2 pin outputs FOSC/4, 
while OSC1 functions as RA7 for digital input and 
output.
• In INTIO2 mode, OSC1 functions as RA7 and 
OSC2 functions as RA6, both for digital input and 
output.
2.6.2 INTOSC OUTPUT FREQUENCY
The internal oscillator block is calibrated at the factory
to produce an INTOSC output frequency of 8.0 MHz. 
The INTRC oscillator operates independently of the
INTOSC source. Any changes in INTOSC across
voltage and temperature are not necessarily reflected
by changes in INTRC and vice versa.
2.6.3 OSCTUNE REGISTER
The internal oscillator’s output has been calibrated at
the factory but can be adjusted in the user’s applica-
tion. This is done by writing to the OSCTUNE register
(Register 2-1). The tuning sensitivity is constant
throughout the tuning range.
When the OSCTUNE register is modified, the INTOSC
and INTRC frequencies will begin shifting to the new
frequency. The INTRC clock will reach the new
frequency within 8 clock cycles (approximately
8*32μs = 256 μs). The INTOSC clock will stabilize
within 1 ms. Code execution continues during this shift.
There is no indication that the shift has occurred.
The OSCTUNE register also implements the INTSRC
and PLLEN bits, which control certain features of the
internal oscillator block. The INTSRC bit allows users
to select which internal oscillator provides the clock
source when the 31 kHz frequency option is selected.
This is covered in greater detail in Section 2.7.1
“Oscillator Control Register”. 
The PLLEN bit controls the operation of the frequency
multiplier, PLL, in internal oscillator modes.
2.6.4 PLL IN INTOSC MODES
The 4x frequency multiplier can be used with the inter-
nal oscillator block to produce faster device clock
speeds than are normally possible with an internal
oscillator. When enabled, the PLL produces a clock
speed of up to 32 MHz.
Unlike HSPLL mode, the PLL is controlled through soft-
ware. The control bit, PLLEN (OSCTUNE<6>), is used
to enable or disable its operation. 
The PLL is available when the device is configured to
use the internal oscillator block as its primary clock
source (FOSC3:FOSC0 = 1001 or 1000). Additionally,
the PLL will only function when the selected output fre-
quency is either 4 MHz or 8 MHz (OSCCON<6:4> = 111
or 110). If both of these conditions are not met, the PLL
is disabled.
The PLLEN control bit is only functional in those internal
oscillator modes where the PLL is available. In all other
modes, it is forced to ‘0’ and is effectively unavailable.
2.6.5 INTOSC FREQUENCY DRIFT
The factory calibrates the internal oscillator block
output (INTOSC) for 8 MHz. However, this frequency
may drift as VDD or temperature changes, which can
affect the controller operation in a variety of ways. It is
possible to adjust the INTOSC frequency by modifying
the value in the OSCTUNE register. This has no effect
on the INTRC clock source frequency.
Tuning the INTOSC source requires knowing when to
make the adjustment, in which direction it should be
made and in some cases, how large a change is
needed. Three compensation techniques are
discussed in Section 2.6.5.1 “Compensating with
the EUSART”, Section 2.6.5.2 “Compensating with
the Timers” and Section 2.6.5.3 “Compensating
with the CCP1 Module in Capture Mode”, but other
techniques may be used.

PIC18F2585/2680/4585/4680

2.6.5.1 Compensating with the EUSART

An adjustment may be required when the EUSART

begins to generate framing errors or receives data with

errors while in Asynchronous mode. Framing errors

indicate that the device clock frequency is too high. To

adjust for this, decrement the value in OSCTUNE to

reduce the clock frequency. On the other hand, errors

in data may suggest that the clock speed is too low. To

compensate, increment OSCTUNE to increase the

clock frequency.

2.6.5.2 Compensating with the Timers

This technique compares device clock speed to some

reference clock. Two timers may be used; one timer is

clocked by the peripheral clock, while the other is

clocked by a fixed reference source, such as the

Timer1 oscillator.

Both timers are cleared, but the timer clocked by the

reference generates interrupts. When an interrupt

occurs, the internally clocked timer is read and both

timers are cleared. If the internally clocked timer value

is greater than expected, then the internal oscillator

block is running too fast. To adjust for this, decrement

the OSCTUNE register.

2.6.5.3 Compensating with the CCP1

Module in Capture Mode

The CCP1 module can use free running Timer1 (or

Timer3), clocked by the internal oscillator block and an

external event with a known period (i.e., AC power

frequency). The time of the first event is captured in the

CCPRxH:CCPRxL registers and is recorded for use

later. When the second event causes a capture, the

time of the first event is subtracted from the time of the

second event. Since the period of the external event is

known, the time difference between events can be

calculated.

If the measured time is much greater than the

calculated time, the internal oscillator block is running

too fast. To compensate, decrement the OSCTUNE

calculated time, the internal oscillator block is running

too slow. To compensate, increment the OSCTUNE

R/W-0 R/W-0(1) U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

INTSRC PLLEN(1) — TUN4 TUN3 TUN2 TUN1 TUN0

bit 7 bit 0

bit 7 INTSRC: Internal Oscillator Low-Frequency Source Select bit

1 = 31.25 kHz device clock derived from 8 MHz INTOSC source (divide-by-256 enabled)

0 = 31 kHz device clock derived directly from INTRC internal oscillator

bit 6 PLLEN: Frequency Multiplier PLL for INTOSC Enable bit(1)

1 = PLL enabled for INTOSC (4 MHz and 8 MHz only)

0 = PLL disabled

Note 1: Available only in certain oscillator configurations; otherwise, this bit is unavailable

and reads as ‘0’. See text for details.

bit 5 Unimplemented: Read as ‘0’

bit 4-0 TUN4:TUN0: Frequency Tuning bits

01111 = Maximum frequency

• •

00001

00000 = Center frequency. Oscillator module is running at the calibrated frequency.

11111

• •

10000 = Minimum frequency

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

2.7 Clock Sources and Oscillator

Switching

Like previous PIC18 devices, the PIC2585/2680/

4585/4680 family includes a feature that allows the

device clock source to be switched from the main

oscillator to an alternate low-frequency clock source.

PIC18F2585/2680/4585/4680 devices offer two alter-

nate clock sources. When an alternate clock source is

enabled, the various power managed operating modes

are available.

Essentially, there are three clock sources for these

devices:

• Primary oscillators

• Secondary oscillators

• Internal oscillator block

The primary oscillators include the External Crystal

and Resonator modes, the External RC modes, the

External Clock modes and the internal oscillator block.

The particular mode is defined by the FOSC3:FOSC0

Configuration bits. The details of these modes are

covered earlier in this chapter.

The secondary oscillators are those external sources

not connected to the OSC1 or OSC2 pins. These

sources may continue to operate even after the

controller is placed in a power managed mode.

PIC18F2585/2680/4585/4680 devices offer the Timer1

oscillator as a secondary oscillator. This oscillator, in all

power managed modes, is often the time base for

functions such as a real-time clock.

Most often, a 32.768 kHz watch crystal is connected

between the RC0/T1OSO/T13CKI and RC1/T1OSI

pins. Like the LP mode oscillator circuit, loading

capacitors are also connected from each pin to ground.

The Timer1 oscillator is discussed in greater detail in

Section 12.3 “Timer1 Oscillator”.

In addition to being a primary clock source, the internal

oscillator block is available as a power managed

mode clock source. The INTRC source is also used as

the clock source for several special features, such as

the WDT and Fail-Safe Clock Monitor.

The clock sources for the PIC18F2585/2680/4585/4680

devices are shown in Figure 2-8. See Section 24.0

“Special Features of the CPU” for Configuration

FIGURE 2-8: PIC18F2585/2680/4585/4680 CLOCK DIAGRAM

PIC18FX585/X680

4 x PLL

FOSC3:FOSC0

Secondary Oscillator

T1OSCEN

Enable

Oscillator

T1OSO

T1OSI

Clock Source Option

for other Modules

OSC1

OSC2

Sleep

Primary Oscillator

HSPLL, INTOSC/PLL

LP, XT, HS, RC, EC

T1OSC

CPU

Peripherals

IDLEN

Postscaler

MUX

8 MHz

4 MHz

2 MHz

1 MHz

500 kHz

125 kHz

250 kHz

OSCCON<6:4>

111

110

101

100

011

010

001

000

31 kHz

INTRC

Source

Internal

Oscillator

Block

WDT, PWRT, FSCM

8 MHz

Internal Oscillator

(INTOSC)

OSCCON<6:4>

Clock

Control

OSCCON<1:0>

Source

8 MHz

31 kHz (INTRC)

OSCTUNE<6>

OSCTUNE<7>

and Two-Speed Startup

PIC18F2585/2680/4585/4680

2.7.1 OSCILLATOR CONTROL REGISTER

The OSCCON register (Register 2-2) controls several

aspects of the device clock’s operation, both in full

power operation and in power managed modes.

The System Clock Select bits, SCS1:SCS0, select the

clock source. The available clock sources are the

primary clock (defined by the FOSC3:FOSC0 Configu-

ration bits), the secondary clock (Timer1 oscillator) and

the internal oscillator block. The clock source changes

immediately after one or more of the bits is written to,

following a brief clock transition interval. The SCS bits

are cleared on all forms of Reset.

The Internal Oscillator Frequency Select bits,

IRCF2:IRCF0, select the frequency output of the

internal oscillator block to drive the device clock. The

choices are the INTRC source, the INTOSC source

(8 MHz) or one of the frequencies derived from the

INTOSC postscaler (31 kHz to 4 MHz). If the internal

oscillator block is supplying the device clock, changing

the states of these bits will have an immediate change

on the internal oscillator’s output. On device Resets,

the default output frequency of the internal oscillator

block is set at 1 MHz.

When an output frequency of 31 kHz is selected

(IRCF2:IRCF0 = 000), users may choose which

internal oscillator acts as the source. This is done with

the INTSRC bit in the OSCTUNE register

(OSCTUNE<7>). Setting this bit selects INTOSC as a

31.25 kHz clock source by enabling the divide-by-256

output of the INTOSC postscaler. Clearing INTSRC

selects INTRC (nominally 31 kHz) as the clock source.

This option allows users to select the tunable and more

precise INTOSC as a clock source, while maintaining

power savings with a very low clock speed. Regardless

of the setting of INTSRC, INTRC always remains the

clock source for features such as the Watchdog Timer

and the Fail-Safe Clock Monitor.

The OSTS, IOFS and T1RUN bits indicate which clock

source is currently providing the device clock. The

OSTS bit indicates that the Oscillator Start-up Timer

has timed out and the primary clock is providing the

device clock in primary clock modes. The IOFS bit

indicates when the internal oscillator block has

stabilized and is providing the device clock in RC Clock

modes. The T1RUN bit (T1CON<6>) indicates when

the Timer1 oscillator is providing the device clock in

secondary clock modes. In power managed modes,

only one of these three bits will be set at any time. If

none of these bits are set, the INTRC is providing the

clock or the internal oscillator block has just started and

is not yet stable.

The IDLEN bit determines if the device goes into Sleep

mode or one of the Idle modes when the SLEEP

instruction is executed.

The use of the flag and control bits in the OSCCON

“Power Managed Modes”.

2.7.2 OSCILLATOR TRANSITIONS

PIC18F2585/2680/4585/4680 devices contain circuitry

to prevent clock “glitches” when switching between

clock sources. A short pause in the device clock occurs

during the clock switch. The length of this pause is the

sum of two cycles of the old clock source and three to

four cycles of the new clock source. This formula

assumes that the new clock source is stable.

Clock transitions are discussed in greater detail in

Section 3.1.2 “Entering Power Managed Modes”.

Note 1: The Timer1 oscillator must be enabled to

select the secondary clock source. The

Timer1 oscillator is enabled by setting the

T1OSCEN bit in the Timer1 Control regis-

ter (T1CON<3>). If the Timer1 oscillator is

not enabled, then any attempt to select a

secondary clock source when executing a

SLEEP instruction will be ignored.

2: It is recommended that the Timer1

oscillator be operating and stable before

executing the SLEEP instruction, or a very

long delay may occur while the Timer1

oscillator starts.

PIC18F2585/2680/4585/4680

R/W-0 R/W-1 R/W-0 R/W-0 R(1) R-0 R/W-0 R/W-0

IDLEN IRCF2 IRCF1 IRCF0 OSTS IOFS SCS1 SCS0

bit 7 bit 0

bit 7 IDLEN: Idle Enable bit

1 = Device enters Idle mode on SLEEP instruction

0 = Device enters Sleep mode on SLEEP instruction

bit 6-4 IRCF2:IRCF0: Internal Oscillator Frequency Select bits

111 = 8 MHz (INTOSC drives clock directly)

110 = 4 MHz

101 = 2 MHz

100 = 1 MHz(3)

011 = 500 kHz

010 = 250 kHz

001 = 125 kHz

000 = 31 kHz (from either INTOSC/256 or INTRC directly)(2)

bit 3 OSTS: Oscillator Start-up Time-out Status bit(1)

1 = Oscillator start-up time-out timer has expired; primary oscillator is running

0 = Oscillator start-up time-out timer is running; primary oscillator is not ready

bit 2 IOFS: INTOSC Frequency Stable bit

1 = INTOSC frequency is stable and the frequency is provided by one of the RC modes

0 = INTOSC frequency is not stable

bit 1-0 SCS1:SCS0: System Clock Select bits

1x = Internal oscillator block

01 = Timer1 oscillator

00 = Primary oscillator

Note 1: Depends on state of the IESO Configuration bit.

2: Source selected by the INTSRC bit (OSCTUNE<7>), see text.

3: Default output frequency of INTOSC on Reset.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 31
PIC18F2585/2680/4585/4680
2.8 Effects of Power Managed Modes 
on the Various Clock Sources
When PRI_IDLE mode is selected, the designated
primary oscillator continues to run without interruption.
For all other power managed modes, the oscillator
using the OSC1 pin is disabled. The OSC1 pin (and
OSC2 pin, if used by the oscillator) will stop oscillating. 
In secondary clock modes (SEC_RUN and
SEC_IDLE), the Timer1 oscillator is operating and
providing the device clock. The Timer1 oscillator may
also run in all power managed modes if required to
clock Timer1 or Timer3.
In internal oscillator modes (RC_RUN and RC_IDLE),
the internal oscillator block provides the device clock
source. The 31 kHz INTRC output can be used directly
to provide the clock and may be enabled to support
various special features, regardless of the power
managed mode (see Section 24.2 “Watchdog Timer
(WDT)”,  Section 24.3 “Two-Speed Start-up” and
Section 24.4 “Fail-Safe Clock Monitor” for more
information on WDT, Two-Speed Start-up and Fail-Safe
Clock Monitor). The INTOSC output at 8 MHz may be
used directly to clock the device or may be divided
down by the postscaler. The INTOSC output is disabled
if the clock is provided directly from the INTRC output.
If the Sleep mode is selected, all clock sources are
stopped. Since all the transistor switching currents
have been stopped, Sleep mode achieves the lowest
current consumption of the device (only leakage
currents).
Enabling any on-chip feature that will operate during
Sleep will increase the current consumed during Sleep.
The INTRC is required to support WDT operation. The
Timer1 oscillator may be operating to support a
real-time clock. Other features may be operating that
do not require a device clock source (i.e., SSP slave,
PSP, INTn pins and others). Peripherals that may add
significant current consumption are listed in
Section 27.2 “DC Characteristics: Power Down and
Supply Current”.
2.9 Power-up Delays
Power-up delays are controlled by two timers, so that
no external Reset circuitry is required for most applica-
tions. The delays ensure that the device is kept in
Reset until the device power supply is stable under nor-
mal circumstances and the primary clock is operating
and stable. For additional information on power-up
delays, see Section 4.5 “Device Reset Timers”.
The first timer is the Power-up Timer (PWRT), which
provides a fixed delay on power-up (parameter 33,
Table 27-10). It is enabled by clearing (= 0) the
PWRTEN Configuration bit. 
The second timer is the Oscillator Start-up Timer
(OST), intended to keep the chip in Reset until the
crystal oscillator is stable (LP, XT and HS modes). The
OST does this by counting 1024 oscillator cycles
before allowing the oscillator to clock the device.
When the HSPLL Oscillator mode is selected, the
device is kept in Reset for an additional 2 ms, following
the HS mode OST delay, so the PLL can lock to the
incoming clock frequency.
There is a delay of interval T
CSD (parameter 38,
Table 27-10), following POR, while the controller
becomes ready to execute instructions. This delay runs
concurrently with any other delays. This may be the
only delay that occurs when any of the EC, RC or INTIO
modes are used as the primary clock source.
TABLE 2-3: OSC1 AND OSC2 PIN STATES IN SLEEP MODE  
OSC Mode OSC1 Pin OSC2 Pin
RC, INTIO1 Floating, external resistor should pull high At logic low (clock/4 output)
RCIO, INTIO2 Floating, external resistor should pull high Configured as PORTA, bit 6
ECIO Floating, pulled by external clock Configured as PORTA, bit 6
EC Floating, pulled by external clock At logic low (clock/4 output)
LP, XT and HS Feedback inverter disabled at quiescent 
voltage level
Feedback inverter disabled at quiescent 
voltage level
Note: See Table 4-2 in Section 4.0 “Reset” for time-outs due to Sleep and MCLR Reset.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

3.0 POWER MANAGED MODES

PIC18F2585/2680/4585/4680 devices offer a total of

seven operating modes for more efficient power

management. These modes provide a variety of

options for selective power conservation in applications

where resources may be limited (i.e., battery-powered

devices).

There are three categories of power managed modes:

• Run modes

• Idle modes

• Sleep mode

These categories define which portions of the device

are clocked and sometimes, what speed. The Run and

Idle modes may use any of the three available clock

sources (primary, secondary or internal oscillator

block); the Sleep mode does not use a clock source.

The power managed modes include several power

saving features offered on previous PIC® devices. One

is the clock switching feature, offered in other PIC18

devices, allowing the controller to use the Timer1

oscillator in place of the primary oscillator. Also

included is the Sleep mode, offered by all PIC devices,

where all device clocks are stopped.

3.1 Selecting Power Managed Modes

Selecting a power managed mode requires two

decisions: if the CPU is to be clocked or not and the

selection of a clock source. The IDLEN bit

(OSCCON<7>) controls CPU clocking, while the

SCS1:SCS0 bits (OSCCON<1:0>) select the clock

source. The individual modes, bit settings, clock sources

and affected modules are summarized in Table 3-1.

3.1.1 CLOCK SOURCES

The SCS1:SCS0 bits allow the selection of one of three

clock sources for power managed modes. They are:

• the primary clock, as defined by the

FOSC3:FOSC0 Configuration bits

• the secondary clock (the Timer1 oscillator)

• the internal oscillator block (for RC modes)

3.1.2 ENTERING POWER MANAGED

MODES

Switching from one power managed mode to another

begins by loading the OSCCON register. The

SCS1:SCS0 bits select the clock source and determine

which Run or Idle mode is to be used. Changing these

bits causes an immediate switch to the new clock

source, assuming that it is running. The switch may

also be subject to clock transition delays. These are

discussed in Section 3.1.3 “Clock Transitions And

Status Indicators” and subsequent sections.

Entry to the Power Managed Idle or Sleep modes is

triggered by the execution of a SLEEP instruction. The

actual mode that results depends on the status of the

IDLEN bit.

Depending on the current mode and the mode being

switched to, a change to a power managed mode does

not always require setting all of these bits. Many

transitions may be done by changing the oscillator

select bits, or changing the IDLEN bit, prior to issuing a

SLEEP instruction. If the IDLEN bit is already

configured correctly, it may only be necessary to

perform a SLEEP instruction to switch to the desired

mode.

TABLE 3-1: POWER MANAGED MODES

Mode

OSCCON Bits Module Clocking

Available Clock and Oscillator Source

IDLEN<7>(1) SCS1:SCS0<1:0> CPU Peripherals

Sleep 0N/A Off Off None – All clocks are disabled

PRI_RUN N/A 00 Clocked Clocked Primary – LP, XT, HS, HSPLL, RC, EC, INTRC(2):

This is the normal full power execution mode.

SEC_RUN N/A 01 Clocked Clocked Secondary – Timer1 Oscillator

RC_RUN N/A 1x Clocked Clocked Internal Oscillator Block(2)

PRI_IDLE 100Off Clocked Primary – LP, XT, HS, HSPLL, RC, EC

SEC_IDLE 101Off Clocked Secondary – Timer1 Oscillator

RC_IDLE 11xOff Clocked Internal Oscillator Block(2)

Note 1: IDLEN reflects its value when the SLEEP instruction is executed.

2: Includes INTOSC and INTOSC postscaler, as well as the INTRC source.

PIC18F2585/2680/4585/4680

3.1.3 CLOCK TRANSITIONS AND STATUS

INDICATORS

The length of the transition between clock sources is

the sum of two cycles of the old clock source and three

to four cycles of the new clock source. This formula

assumes that the new clock source is stable.

Three bits indicate the current clock source and its

status. They are:

• OSTS (OSCCON<3>)

• IOFS (OSCCON<2>)

• T1RUN (T1CON<6>)

In general, only one of these bits will be set while in a

given power managed mode. When the OSTS bit is

set, the primary clock is providing the device clock.

When the IOFS bit is set, the INTOSC output is provid-

ing a stable 8 MHz clock source to a divider that

actually drives the device clock. When the T1RUN bit is

set, the Timer1 oscillator is providing the clock. If none

of these bits are set, then either the INTRC clock

source is clocking the device, or the INTOSC source is

not yet stable.

If the internal oscillator block is configured as the

primary clock source by the FOSC3:FOSC0 Configura-

tion bits, then both the OSTS and IOFS bits may be set

when in PRI_RUN or PRI_IDLE modes. This indicates

that the primary clock (INTOSC output) is generating a

stable 8 MHz output. Entering another RC power

managed mode at the same frequency would clear the

OSTS bit.

3.1.4 MULTIPLE SLEEP COMMANDS

The power managed mode that is invoked with the

SLEEP instruction is determined by the setting of the

IDLEN bit at the time the instruction is executed. If

another SLEEP instruction is executed, the device will

enter the power managed mode specified by IDLEN at

that time. If IDLEN has changed, the device will enter

the new power managed mode specified by the new

setting.

3.2 Run Modes

In the Run modes, clocks to both the core and

peripherals are active. The difference between these

modes is the clock source.

3.2.1 PRI_RUN MODE

The PRI_RUN mode is the normal, full power execution

mode of the microcontroller. This is also the default

mode upon a device Reset, unless Two-Speed Start-up

is enabled (see Section 24.3 “Two-Speed Start-up”

for details). In this mode, the OSTS bit is set. The IOFS

bit may be set if the internal oscillator block is the

primary clock source (see Section 2.7.1 “Oscillator

Control Register”).

3.2.2 SEC_RUN MODE

The SEC_RUN mode is the compatible mode to the

“clock switching” feature offered in other PIC18

devices. In this mode, the CPU and peripherals are

clocked from the Timer1 oscillator. This gives users the

option of lower power consumption while still using a

high accuracy clock source.

SEC_RUN mode is entered by setting the SCS1:SCS0

bits to ‘01’. The device clock source is switched to the

Timer1 oscillator (see Figure 3-1), the primary oscilla-

tor is shut down, the T1RUN bit (T1CON<6>) is set and

the OSTS bit is cleared.

On transitions from SEC_RUN mode to PRI_RUN, the

peripherals and CPU continue to be clocked from the

Timer1 oscillator while the primary clock is started.

When the primary clock becomes ready, a clock switch

back to the primary clock occurs (see Figure 3-2).

When the clock switch is complete, the T1RUN bit is

cleared, the OSTS bit is set and the primary clock is

providing the clock. The IDLEN and SCS bits are not

affected by the wake-up; the Timer1 oscillator

continues to run.

Note 1: Caution should be used when modifying a

single IRCF bit. If VDD is less than 3V, it is

possible to select a higher clock speed

than is supported by the low VDD.

Improper device operation may result if

the VDD/FOSC specifications are violated.

2: Executing a SLEEP instruction does not

necessarily place the device into Sleep

mode. It acts as the trigger to place the

controller into either the Sleep mode or

one of the Idle modes, depending on the

setting of the IDLEN bit.

Note: The Timer1 oscillator should already be

running prior to entering SEC_RUN mode.

If the T1OSCEN bit is not set when the

SCS1:SCS0 bits are set to ‘01’, entry to

SEC_RUN mode will not occur. If the

Timer1 oscillator is enabled but not yet

running, device clocks will be delayed until

the oscillator has started. In such situa-

tions, initial oscillator operation is far from

stable and unpredictable operation may

result.

PIC18F2585/2680/4585/4680

FIGURE 3-1: TRANSITION TIMING FOR ENTRY TO SEC_RUN MODE

FIGURE 3-2: TRANSITION TIMING FROM SEC_RUN MODE TO PRI_RUN MODE (HSPLL)

3.2.3 RC_RUN MODE

In RC_RUN mode, the CPU and peripherals are

clocked from the internal oscillator block using the

INTOSC multiplexer; the primary clock is shut down.

When using the INTRC source, this mode provides the

best power conservation of all the Run modes, while

still executing code. It works well for user applications

which are not highly timing sensitive or do not require

high-speed clocks at all times.

If the primary clock source is the internal oscillator

block (either INTRC or INTOSC), there are no distin-

guishable differences between PRI_RUN and

RC_RUN modes during execution. However, a clock

switch delay will occur during entry to and exit from

RC_RUN mode. Therefore, if the primary clock source

is the internal oscillator block, the use of RC_RUN

mode is not recommended.

This mode is entered by setting SCS1 to ‘1’. Although

it is ignored, it is recommended that SCS0 also be

cleared; this is to maintain software compatibility with

future devices. When the clock source is switched to

the INTOSC multiplexer (see Figure 3-3), the primary

oscillator is shut down and the OSTS bit is cleared. The

IRCF bits may be modified at any time to immediately

change the clock speed.

Q4Q3Q2

OSC1

Peripheral

Program

T1OSI

Counter

Clock

CPU

Clock

PC + 2PC

123

n-1

Clock Transition

Q4Q3Q2 Q1 Q3Q2

PC + 4

Q1 Q3 Q4

OSC1

Peripheral

Program PC

T1OSI

PLL Clock

PC + 4

Output

Q3 Q4 Q1

CPU Clock

PC + 2

Clock

Counter

Q2 Q2 Q3

Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.

SCS1:SCS0 bits changed

TOST(1) TPLL(1)

12 n-1n

Clock

OSTS bit set

Transition

Note: Caution should be used when modifying a

single IRCF bit. If VDD is less than 3V, it is

possible to select a higher clock speed

than is supported by the low VDD.

Improper device operation may result if

the VDD/FOSC specifications are violated.

PIC18F2585/2680/4585/4680

If the IRCF bits and the INTSRC bit are all clear, the

INTOSC output is not enabled and the IOFS bit will

remain clear; there will be no indication of the current

clock source. The INTRC source is providing the

device clocks.

If the IRCF bits are changed from all clear (thus,

enabling the INTOSC output) or if INTSRC is set, the

IOFS bit becomes set after the INTOSC output

becomes stable. Clocks to the device continue while

the INTOSC source stabilizes after an interval of

TIOBST.

If the IRCF bits were previously at a non-zero value or

if INTSRC was set before setting SCS1 and the

INTOSC source was already stable, the IOFS bit will

remain set.

On transitions from RC_RUN mode to PRI_RUN mode,

the device continues to be clocked from the INTOSC

multiplexer while the primary clock is started. When the

primary clock becomes ready, a clock switch to the

primary clock occurs (see Figure 3-4). When the clock

switch is complete, the IOFS bit is cleared, the OSTS

bit is set and the primary clock is providing the device

clock. The IDLEN and SCS bits are not affected by the

switch. The INTRC source will continue to run if either

the WDT or the Fail-Safe Clock Monitor is enabled.

FIGURE 3-3: TRANSITION TIMING TO RC_RUN MODE

FIGURE 3-4: TRANSITION TIMING FROM RC_RUN MODE TO PRI_RUN MODE

Q4Q3Q2

OSC1

Peripheral

Program

INTRC

Counter

Clock

CPU

Clock

PC + 2PC

123 n-1n

Clock Transition

Q4Q3Q2 Q1 Q3Q2

PC + 4

Q1 Q3 Q4

OSC1

Peripheral

Program PC

INTOSC

PLL Clock

PC + 4

Output

Q3 Q4 Q1

CPU Clock

PC + 2

Clock

Counter

Q2 Q2 Q3

Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.

SCS1:SCS0 bits changed

TPLL(1)

12 n-1n

Clock

OSTS bit set

Transition

Multiplexer

TOST(1)

PIC18F2585/2680/4585/4680

3.3 Sleep Mode

The Power Managed Sleep mode in the

PIC18F2585/2680/4585/4680 devices is identical to

the legacy Sleep mode offered in all other PIC devices.

It is entered by clearing the IDLEN bit (the default state

on device Reset) and executing the SLEEP instruction.

This shuts down the selected oscillator (Figure 3-5). All

clock source status bits are cleared.

Entering the Sleep mode from any other mode does not

require a clock switch. This is because no clocks are

needed once the controller has entered Sleep. If the

WDT is selected, the INTRC source will continue to

operate. If the Timer1 oscillator is enabled, it will also

continue to run.

When a wake event occurs in Sleep mode (by interrupt,

Reset or WDT time-out), the device will not be clocked

until the clock source selected by the SCS1:SCS0 bits

becomes ready (see Figure 3-6), or it will be clocked

from the internal oscillator block if either the

Two-Speed Start-up or the Fail-Safe Clock Monitor are

enabled (see Section 24.0 “Special Features of the

CPU”). In either case, the OSTS bit is set when the

primary clock is providing the device clocks. The

IDLEN and SCS bits are not affected by the wake-up.

3.4 Idle Modes

The Idle modes allow the controller’s CPU to be

selectively shut down while the peripherals continue to

operate. Selecting a particular Idle mode allows users

to further manage power consumption.

If the IDLEN bit is set to a ‘1’ when a SLEEP instruction is

executed, the peripherals will be clocked from the clock

source selected using the SCS1:SCS0 bits; however, the

CPU will not be clocked. The clock source status bits are

not affected. Setting IDLEN and executing a SLEEP

instruction provides a quick method of switching from a

given Run mode to its corresponding Idle mode.

If the WDT is selected, the INTRC source will continue

to operate. If the Timer1 oscillator is enabled, it will also

continue to run.

Since the CPU is not executing instructions, the only

exits from any of the Idle modes are by interrupt, WDT

time-out or a Reset. When a wake event occurs, CPU

execution is delayed by an interval of TCSD

(parameter 38, Table 27-10) while it becomes ready to

execute code. When the CPU begins executing code,

it resumes with the same clock source for the current

Idle mode. For example, when waking from RC_IDLE

mode, the internal oscillator block will clock the CPU

and peripherals (in other words, RC_RUN mode). The

IDLEN and SCS bits are not affected by the wake-up.

While in any Idle mode or the Sleep mode, a WDT

time-out will result in a WDT wake-up to the Run mode

currently specified by the SCS1:SCS0 bits.

FIGURE 3-5: TRANSITION TIMING FOR ENTRY TO SLEEP MODE

FIGURE 3-6: TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL)

Q4Q3Q2

OSC1

Peripheral

Sleep

Program

Q1Q1

Counter

Clock

CPU

Clock

PC + 2PC

Q3 Q4 Q1 Q2

OSC1

Peripheral

Program PC

PLL Clock

Q3 Q4

Output

CPU Clock

Q1 Q2 Q3 Q4 Q1 Q2

Clock

Counter PC + 6

PC + 4

Q1 Q2 Q3 Q4

Wake Event

Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.

TOST(1) TPLL(1)

OSTS bit set

PC + 2

PIC18F2585/2680/4585/4680

3.4.1 PRI_IDLE MODE

This mode is unique among the three Low-Power Idle

modes, in that it does not disable the primary device

clock. For timing sensitive applications, this allows for

the fastest resumption of device operation with its more

accurate primary clock source, since the clock source

does not have to “warm up” or transition from another

oscillator.

PRI_IDLE mode is entered from PRI_RUN mode by

setting the IDLEN bit and executing a SLEEP instruc-

tion. If the device is in another Run mode, set IDLEN

first, then clear the SCS bits and execute SLEEP.

Although the CPU is disabled, the peripherals continue

to be clocked from the primary clock source specified

by the FOSC3:FOSC0 Configuration bits. The OSTS

bit remains set (see Figure 3-7).

When a wake event occurs, the CPU is clocked from the

primary clock source. A delay of interval TCSD is

required between the wake event and when code

execution starts. This is required to allow the CPU to

become ready to execute instructions. After the

wake-up, the OSTS bit remains set. The IDLEN and

SCS bits are not affected by the wake-up (see

Figure 3-8).

3.4.2 SEC_IDLE MODE

In SEC_IDLE mode, the CPU is disabled but the

peripherals continue to be clocked from the Timer1

oscillator. This mode is entered from SEC_RUN by set-

ting the IDLEN bit and executing a SLEEP instruction. If

the device is in another Run mode, set the IDLEN bit

first, then set the SCS1:SCS0 bits to ‘01’ and execute

SLEEP. When the clock source is switched to the

Timer1 oscillator, the primary oscillator is shut down,

the OSTS bit is cleared and the T1RUN bit is set.

When a wake event occurs, the peripherals continue to

be clocked from the Timer1 oscillator. After an interval of

CSD following the wake event, the CPU begins

executing code being clocked by the Timer1 oscillator.

The IDLEN and SCS bits are not affected by the

wake-up; the Timer1 oscillator continues to run (see

Figure 3-8).

FIGURE 3-7: TRANSITION TIMING FOR ENTRY TO IDLE MODE

FIGURE 3-8: TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE

Note: The Timer1 oscillator should already be

running prior to entering SEC_IDLE mode.

If the T1OSCEN bit is not set when the

SLEEP instruction is executed, the SLEEP

instruction will be ignored and entry to

SEC_IDLE mode will not occur. If the

Timer1 oscillator is enabled but not yet run-

ning, peripheral clocks will be delayed until

the oscillator has started. In such situations,

initial oscillator operation is far from stable

and unpredictable operation may result.

Peripheral

Program PC PC + 2

OSC1

Q3 Q4 Q1

CPU Clock

Clock

Counter

OSC1

Peripheral

Program PC

CPU Clock

Q1 Q3 Q4

Clock

Counter

Wake Event

TCSD

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 39
PIC18F2585/2680/4585/4680
3.4.3 RC_IDLE MODE
In RC_IDLE mode, the CPU is disabled but the periph-
erals continue to be clocked from the internal oscillator
block using the INTOSC multiplexer. This mode allows
for controllable power conservation during Idle periods.
From RC_RUN, this mode is entered by setting the
IDLEN bit and executing a SLEEP instruction. If the
device is in another Run mode, first set IDLEN, then set
the SCS1 bit and execute SLEEP. Although its value is
ignored, it is recommended that SCS0 also be cleared;
this is to maintain software compatibility with future
devices. The INTOSC multiplexer may be used to
select a higher clock frequency, by modifying the IRCF
bits, before executing the SLEEP instruction. When the
clock source is switched to the INTOSC multiplexer, the
primary oscillator is shut down and the OSTS bit is
cleared.
If the IRCF bits are set to any non-zero value or the
INTSRC bit is set, the INTOSC output is enabled. The
IOFS bit becomes set, after the INTOSC output
becomes stable, after an interval of TIOBST
(parameter 39, Table 27-10). Clocks to the peripherals
continue while the INTOSC source stabilizes. If the
IRCF bits were previously at a non-zero value, or
INTSRC was set before the SLEEP instruction was
executed and the INTOSC source was already stable,
the IOFS bit will remain set. If the IRCF bits and
INTSRC are all clear, the INTOSC output will not be
enabled, the IOFS bit will remain clear and there will be
no indication of the current clock source.
When a wake event occurs, the peripherals continue to
be clocked from the INTOSC multiplexer. After a delay
of TCSD following the wake event, the CPU begins
executing code being clocked by the INTOSC multi-
plexer. The IDLEN and SCS bits are not affected by the
wake-up. The INTRC source will continue to run if
either the WDT or the Fail-Safe Clock Monitor is
enabled.
3.5 Exiting Idle and Sleep Modes
An exit from Sleep mode or any of the Idle modes is
triggered by an interrupt, a Reset or a WDT time-out.
This section discusses the triggers that cause exits
from power managed modes. The clocking subsystem
actions are discussed in each of the power managed
modes (see Section 3.2 “Run Modes”, Section 3.3
“Sleep Mode” and Section 3.4 “Idle Modes”). 
3.5.1 EXIT BY INTERRUPT
Any of the available interrupt sources can cause the
device to exit from an Idle mode or the Sleep mode to
a Run mode. To enable this functionality, an interrupt
source must be enabled by setting its enable bit in one
of the INTCON or PIE registers. The exit sequence is
initiated when the corresponding interrupt flag bit is set.
On all exits from Idle or Sleep modes by interrupt, code
execution branches to the interrupt vector if the
GIE/GIEH bit (INTCON<7>) is set. Otherwise, code
execution continues or resumes without branching
(see Section 9.0 “Interrupts”).
A fixed delay of interval TCSD following the wake event
is required when leaving Sleep and Idle modes. This
delay is required for the CPU to prepare for execution.
Instruction execution resumes on the first clock cycle
following this delay.
3.5.2 EXIT BY WDT TIME-OUT
A WDT time-out will cause different actions depending
on which power managed mode the device is in when
the time-out occurs.
If the device is not executing code (all Idle modes and
Sleep mode), the time-out will result in an exit from the
power managed mode (see Section 3.2 “Run Modes”
and  Section 3.3 “Sleep Mode”). If the device is
executing code (all Run modes), the time-out will result
in a WDT Reset (see Section 24.2 “Watchdog Timer
(WDT)”). 
The WDT timer and postscaler are cleared by execut-
ing a SLEEP or CLRWDT instruction, the loss of a
currently selected clock source (if the Fail-Safe Clock
Monitor is enabled) and modifying the IRCF bits in the
OSCCON register if the internal oscillator block is the
device clock source.
3.5.3 EXIT BY RESET
Normally, the device is held in Reset by the Oscillator
Start-up Timer (OST) until the primary clock becomes
ready. At that time, the OSTS bit is set and the device
begins executing code. If the internal oscillator block is
the new clock source, the IOFS bit is set instead. 
The exit delay time from Reset to the start of code
execution depends on both the clock sources before
and after the wake-up and the type of oscillator if the
new clock source is the primary clock. Exit delays are
summarized in Table 3-2.
Code execution can begin before the primary clock
becomes ready. If either the Two-Speed Start-up (see
Section 24.3 “Two-Speed Start-up”) or Fail-Safe
Clock Monitor (see Section 24.4 “Fail-Safe Clock
Monitor”) is enabled, the device may begin execution
as soon as the Reset source has cleared. Execution is
clocked by the INTOSC multiplexer driven by the
internal oscillator block. Execution is clocked by the
internal oscillator block until either the primary clock
becomes ready or a power managed mode is entered
before the primary clock becomes ready; the primary
clock is then shut down.

PIC18F2585/2680/4585/4680

3.5.4 EXIT WITHOUT AN OSCILLATOR

START-UP DELAY

Certain exits from power managed modes do not

invoke the OST at all. There are two cases:

• PRI_IDLE mode where the primary clock source

is not stopped; and

• the primary clock source is not any of the LP, XT,

HS or HSPLL modes.

In these instances, the primary clock source either

does not require an oscillator start-up delay, since it is

already running (PRI_IDLE), or normally does not

require an oscillator start-up delay (RC, EC and INTIO

Oscillator modes). However, a fixed delay of interval

TCSD following the wake event is still required when

leaving Sleep and Idle modes to allow the CPU to pre-

pare for execution. Instruction execution resumes on

the first clock cycle following this delay.

TABLE 3-2: EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE

(BY CLOCK SOURCES)

Clock Source

Before Wake-up

Clock Source

After Wake-up Exit Delay Clock Ready Status

Bit (OSCCON)

Primary Device Clock

(PRI_IDLE mode)

LP, XT, HS

TCSD(2)

OSTSHSPLL

EC, RC

INTRC(1) —

INTOSC(3) IOFS

T1OSC or INTRC(1)

LP, XT, HS TOST(4)

OSTSHSPLL TOST + trc(4)

EC, RC TCSD(2)

INTRC(1) —

INTOSC(2) TIOBST(5) IOFS

INTOSC(3)

LP, XT, HS TOST(5)

OSTSHSPLL TOST + trc(4)

EC, RC TCSD(2)

INTRC(1) —

INTOSC(2) None IOFS

None

(Sleep mode)

LP, XT, HS TOST(4)

OSTSHSPLL TOST + trc(4)

EC, RC TCSD(2)

INTRC(1) —

INTOSC(2) TIOBST(5) IOFS

Note 1: In this instance, refers specifically to the 31 kHz INTRC clock source.

2: TCSD (parameter 38) is a required delay when waking from Sleep and all Idle modes and runs concurrently

with any other required delays (see Section 3.4 “Idle Modes”).

3: Includes both the INTOSC 8 MHz source and postscaler derived frequencies.

4: TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL Lock-out Timer (parameter F12); it is

also designated as TPLL.

5: Execution continues during TIOBST (parameter 39), the INTOSC stabilization period.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 41
PIC18F2585/2680/4585/4680
4.0 RESET
The PIC18F2585/2680/4585/4680 devices differentiate
between various kinds of Reset: 
a) Power-on Reset (POR) 
b) MCLR Reset during normal operation
c) MCLR Reset during power managed modes 
d) Watchdog Timer (WDT) Reset (during 
execution)
e) Programmable Brown-out Reset (BOR) 
f) RESET Instruction
g) Stack Full Reset
h) Stack Underflow Reset
This section discusses Resets generated by MCLR,
POR and BOR and covers the operation of the various
start-up timers. Stack Reset events are covered in
Section 5.1.2.4 “Stack Full and Underflow Resets”.
WDT Resets are covered in Section 24.2 “Watchdog
Timer (WDT)”.
A simplified block diagram of the On-Chip Reset Circuit
is shown in Figure 4-1.
4.1 RCON Register
Device Reset events are tracked through the RCON
register (Register 4-1). The lower five bits of the
register indicate that a specific Reset event has
occurred. In most cases, these bits can only be cleared
by the event and must be set by the application after
the event. The state of these flag bits, taken together,
can be read to indicate the type of Reset that just
occurred. This is described in more detail in
Section 4.6 “Reset State of Registers”.
The RCON register also has control bits for setting
interrupt priority (IPEN) and software control of the
BOR (SBOREN). Interrupt priority is discussed in
Section 9.0 “Interrupts”. BOR is covered in
Section 4.4 “Brown-out Reset (BOR)”.
FIGURE 4-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT        
S
RQ
External Reset
MCLR
VDD
OSC1
WDT
Time-out
VDD Rise
Detect
OST/PWRT
INTRC
(1)
POR Pulse
OST
10-bit Ripple Counter
PWRT
Chip_Reset
11-bit Ripple Counter
Enable OST(2)
Enable PWRT
Note 1: This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin.
2: See Table 4-2 for time-out situations.
Brown-out
Reset
BOREN
RESET
Instruction
Stack
Pointer
Stack Full/Underflow Reset
Sleep
( )_IDLE
1024 Cycles
65.5 ms
32 μs
MCLRE

PIC18F2585/2680/4585/4680

R/W-0 R/W-1(1) U-0 R/W-1 R-1 R-1 R/W-0(2) R/W-0

IPEN SBOREN —RITO PD POR BOR

bit 7 bit 0

bit 7 IPEN: Interrupt Priority Enable bit

1 = Enable priority levels on interrupts

0 = Disable priority levels on interrupts (16CXXX Compatibility mode)

bit 6 SBOREN: BOR Software Enable bit(1)

If BOREN1:BOREN0 = 01:

1 = BOR is enabled

0 = BOR is disabled

If BOREN1:BOREN0 = 00, 10 or 11:

Bit is disabled and read as ‘0’.

bit 5 Unimplemented: Read as ‘0’

bit 4 RI: RESET Instruction Flag bit

1 = The RESET instruction was not executed (set by firmware only)

0 = The RESET instruction was executed causing a device Reset (must be set in software after

a Brown-out Reset occurs)

bit 3 TO: Watchdog Time-out Flag bit

1 = Set by power-up, CLRWDT instruction or SLEEP instruction

0 = A WDT time-out occurred

bit 2 PD: Power-down Detection Flag bit

1 = Set by power-up or by the CLRWDT instruction

0 = Set by execution of the SLEEP instruction

bit 1 POR: Power-on Reset Status bit(2)

1 = A Power-on Reset has not occurred (set by firmware only)

0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs)

bit 0 BOR: Brown-out Reset Status bit

1 = A Brown-out Reset has not occurred (set by firmware only)

0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs)

Note 1: If SBOREN is enabled, its Reset state is ‘1’; otherwise, it is ‘0’.

2: The actual Reset value of POR is determined by the type of device Reset. See the

notes following this register and Section 4.6 “Reset State of Registers” for

additional information.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Note 1: It is recommended that the POR bit be set after a Power-on Reset has been

detected so that subsequent Power-on Resets may be detected.

2: Brown-out Reset is said to have occurred when BOR is ‘0’ and POR is ‘1’ (assuming

that POR was set to ‘1’ by software immediately after POR).

PIC18F2585/2680/4585/4680

4.2 Master Clear Reset (MCLR)

The MCLR pin provides a method for triggering an

external Reset of the device. A Reset is generated by

holding the pin low. These devices have a noise filter in

the MCLR Reset path which detects and ignores small

pulses.

The MCLR pin is not driven low by any internal Resets,

including the WDT.

In PIC18F2585/2680/4585/4680 devices, the MCLR

input can be disabled with the MCLRE Configuration

bit. When MCLR is disabled, the pin becomes a digital

input. See Section 10.5 “PORTE, TRISE and LATE

Registers” for more information.

4.3 Power-on Reset (POR)

A Power-on Reset pulse is generated on-chip

whenever VDD rises above a certain threshold. This

allows the device to start in the initialized state when

VDD is adequate for operation.

To take advantage of the POR circuitry, tie the MCLR

pin through a resistor (1 kΩ to 10 kΩ) to VDD. This will

eliminate external RC components usually needed to

create a Power-on Reset delay. A minimum rise rate for

VDD is specified (parameter D004). For a slow rise

time, see Figure 4-2.

When the device starts normal operation (i.e., exits the

Reset condition), device operating parameters

(voltage, frequency, temperature, etc.) must be met to

ensure operation. If these conditions are not met, the

device must be held in Reset until the operating

conditions are met.

POR events are captured by the POR bit (RCON<1>).

The state of the bit is set to ‘0’ whenever a POR occurs;

it does not change for any other Reset event. POR is

not reset to ‘1’ by any hardware event. To capture

multiple events, the user manually resets the bit to ‘1’

in software following any POR.

FIGURE 4-2: EXTERNAL POWER-ON

RESET CIRCUIT (FOR

SLOW VDD POWER-UP)

Note 1: External Power-on Reset circuit is required

only if the VDD power-up slope is too slow.

The diode D helps discharge the capacitor

quickly when VDD powers down.

2: R < 40 kΩ is recommended to make sure that

the voltage drop across R does not violate

the device’s electrical specification.

3: R1 ≥ 1 kΩ will limit any current flowing into

MCLR from external capacitor C, in the event

of MCLR/VPP pin breakdown, due to Electro-

static Discharge (ESD) or Electrical

Overstress (EOS).

VDD

MCLR

PIC18FXXXX

VDD

PIC18F2585/2680/4585/4680

4.4 Brown-out Reset (BOR)

PIC18F2585/2680/4585/4680 devices implement a BOR

circuit that provides the user with a number of configura-

tion and power-saving options. The BOR is controlled by

the BORV1:BORV0 and BOREN1:BOREN0 Configura-

tion bits. There are a total of four BOR configurations

which are summarized in Table 4-1.

The BOR threshold is set by the BORV1:BORV0 bits. If

BOR is enabled (any values of BOREN1:BOREN0,

except ‘00’), any drop of VDD below VBOR (parameter

D005) for greater than TBOR (parameter 35) will reset

the device. A Reset may or may not occur if VDD falls

below VBOR for less than TBOR. The chip will remain in

Brown-out Reset until VDD rises above VBOR.

If the Power-up Timer is enabled, it will be invoked after

VDD rises above VBOR; it then will keep the chip in

Reset for an additional time delay, TPWRT

(parameter 33). If VDD drops below VBOR while the

Power-up Timer is running, the chip will go back into a

Brown-out Reset and the Power-up Timer will be

initialized. Once VDD rises above VBOR, the Power-up

Timer will execute the additional time delay.

BOR and the Power-on Timer (PWRT) are

independently configured. Enabling BOR Reset does

not automatically enable the PWRT.

4.4.1 SOFTWARE ENABLED BOR

When BOREN1:BOREN0 = 01, the BOR can be

enabled or disabled by the user in software. This is

done with the control bit, SBOREN (RCON<6>).

Setting SBOREN enables the BOR to function as

previously described. Clearing SBOREN disables the

BOR entirely. The SBOREN bit operates only in this

mode; otherwise it is read as ‘0’.

Placing the BOR under software control gives the user

the additional flexibility of tailoring the application to its

environment without having to reprogram the device to

change BOR configuration. It also allows the user to

tailor device power consumption in software by elimi-

nating the incremental current that the BOR consumes.

While the BOR current is typically very small, it may

have some impact in low-power applications.

4.4.2 DETECTING BOR

When BOR is enabled, the BOR bit always resets to ‘0’

on any BOR or POR event. This makes it difficult to

determine if a BOR event has occurred just by reading

the state of BOR alone. A more reliable method is to

simultaneously check the state of both POR and BOR.

This assumes that the POR bit is reset to ‘1’ in software

immediately after any POR event. IF BOR is ‘0’ while

POR is ‘1’, it can be reliably assumed that a BOR event

has occurred.

4.4.3 DISABLING BOR IN SLEEP MODE

When BOREN1:BOREN0 = 10, the BOR remains

under hardware control and operates as previously

described. Whenever the device enters Sleep mode,

however, the BOR is automatically disabled. When the

device returns to any other operating mode, BOR is

automatically re-enabled.

This mode allows for applications to recover from

brown-out situations, while actively executing code,

when the device requires BOR protection the most. At

the same time, it saves additional power in Sleep mode

by eliminating the small incremental BOR current.

TABLE 4-1: BOR CONFIGURATIONS

Note: Even when BOR is under software control,

the BOR Reset voltage level is still set by

the BORV1:BORV0 Configuration bits. It

cannot be changed in software.

BOR Configuration Status of

SBOREN

(RCON<6>)

BOR Operation

BOREN1 BOREN0

00Unavailable BOR disabled; must be enabled by reprogramming the Configuration bits.

01Available BOR enabled in software; operation controlled by SBOREN.

10Unavailable BOR enabled in hardware in Run and Idle modes, disabled during Sleep

mode.

11Unavailable BOR enabled in hardware; must be disabled by reprogramming the

Configuration bits.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 45
PIC18F2585/2680/4585/4680
4.5 Device Reset Timers
PIC18F2585/2680/4585/4680 devices incorporate
three separate on-chip timers that help regulate the
Power-on Reset process. Their main function is to
ensure that the device clock is stable before code is
executed. These timers are:
• Power-up Timer (PWRT)
• Oscillator Start-up Timer (OST)
• PLL Lock Time-out
4.5.1 POWER-UP TIMER (PWRT)
The Power-up Timer (PWRT) of PIC18F2585/2680/
4585/4680 devices is an 11-bit counter which uses the
INTRC source as the clock input. This yields an
approximate time interval of 2048 x 32 μs=65.6ms.
While the PWRT is counting, the device is held in
Reset.
The power-up time delay depends on the INTRC clock
and will vary from chip to chip due to temperature and
process variation. See DC parameter 33 for details.
The PWRT is enabled by clearing the PWRTEN
Configuration bit. 
4.5.2 OSCILLATOR START-UP TIMER 
(OST)
The Oscillator Start-up Timer (OST) provides a 1024
oscillator cycle (from OSC1 input) delay after the
PWRT delay is over (parameter 33). This ensures that
the crystal oscillator or resonator has started and
stabilized.
The OST time-out is invoked only for XT, LP, HS and
HSPLL modes and only on Power-on Reset or on exit
from most power managed modes.
4.5.3 PLL LOCK TIME-OUT
With the PLL enabled in its PLL mode, the time-out
sequence following a Power-on Reset is slightly
different from other oscillator modes. A separate timer
is used to provide a fixed time-out that is sufficient for
the PLL to lock to the main oscillator frequency. This
PLL lock time-out (TPLL) is typically 2 ms and follows
the oscillator start-up time-out.
4.5.4 TIME-OUT SEQUENCE
On power-up, the time-out sequence is as follows:
1. After the POR pulse has cleared, PWRT
time-out is invoked (if enabled). 
2. Then, the OST is activated. 
The total time-out will vary based on oscillator configu-
ration and the status of the PWRT. Figure 4-3,
Figure 4-4, Figure 4-5, Figure 4-6 and Figure 4-7 all
depict time-out sequences on power-up, with the
Power-up Timer enabled and the device operating in
HS Oscillator mode. Figures 4-3 through 4-6 also apply
to devices operating in XT or LP modes. For devices in
RC mode and with the PWRT disabled, on the other
hand, there will be no time-out at all.
Since the time-outs occur from the POR pulse, if MCLR
is kept low long enough, all time-outs will expire.
Bringing MCLR high will begin execution immediately
(Figure 4-5). This is useful for testing purposes or to
synchronize more than one PIC18FXXXX device
operating in parallel.
TABLE 4-2: TIME-OUT IN VARIOUS SITUATIONS  
Oscillator
Configuration
Power-up(2) and Brown-out Exit from 
Power Managed Mode
PWRTEN = 0PWRTEN = 1
HSPLL 66 ms(1) + 1024 TOSC + 2 ms(2) 1024 TOSC + 2 ms(2) 1024 TOSC + 2 ms(2)
HS, XT, LP 66 ms(1) + 1024 TOSC 1024 TOSC 1024 TOSC
EC, ECIO 66 ms(1) ——
RC, RCIO 66 ms(1) ——
INTIO1, INTIO2 66 ms(1) ——
Note 1: 66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay.
2: 2 ms is the nominal time required for the PLL to lock.

PIC18F2585/2680/4585/4680

FIGURE 4-3: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD, VDD RISE < TPWRT)

FIGURE 4-4: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1

FIGURE 4-5: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2

TPWRT

TOST

VDD

MCLR

INTERNAL POR

PWRT TIME-OUT

OST TIME-OUT

INTERNAL RESET

TPWRT

TOST

VDD

MCLR

INTERNAL POR

PWRT TIME-OUT

OST TIME-OUT

INTERNAL RESET

VDD

MCLR

INTERNAL POR

PWRT TIME-OUT

OST TIME-OUT

INTERNAL RESET

TPWRT

TOST

PIC18F2585/2680/4585/4680

FIGURE 4-6: SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT)

FIGURE 4-7: TIME-OUT SEQUENCE ON POR W/PLL ENABLED (MCLR TIED TO VDD)

VDD

MCLR

INTERNAL POR

PWRT TIME-OUT

OST TIME-OUT

INTERNAL RESET

0V 1V

TPWRT

TOST

TPWRT

TOST

VDD

MCLR

INTERNAL POR

PWRT TIME-OUT

OST TIME-OUT

INTERNAL RESET

PLL TIME-OUT

TPLL

Note: TOST = 1024 clock cycles.

TPLL ≈ 2 ms max. First three stages of the PWRT timer.

PIC18F2585/2680/4585/4680

4.6 Reset State of Registers

Most registers are unaffected by a Reset. Their status

is unknown on POR and unchanged by all other

Resets. The other registers are forced to a “Reset

state” depending on the type of Reset that occurred.

Most registers are not affected by a WDT wake-up,

since this is viewed as the resumption of normal

operation. Status bits from the RCON register, RI, TO,

PD, POR and BOR, are set or cleared differently in

different Reset situations, as indicated in Table 4-3.

These bits are used in software to determine the nature

of the Reset.

Table 4-4 describes the Reset states for all of the

Special Function Registers. These are categorized by

Power-on and Brown-out Resets, Master Clear and

WDT Resets and WDT wake-ups.

TABLE 4-3: STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION FOR

RCON REGISTER

Condition Program

Counter

RCON Register STKPTR Register

SBOREN RI TO PD POR BOR STKFUL STKUNF

Power-on Reset 0000h 1 11100 0 0

RESET Instruction 0000h u(2) 0uuuu u u

Brown-out 0000h u(2) 111u0 u u

MCLR during Power Managed

Run modes

0000h u(2) u1uuu u u

MCLR during Power Managed

Idle modes and Sleep mode

0000h u(2) u10uu u u

WDT Time-out during Full Power

or Power Managed Run modes

0000h u(2) u0uuu u u

MCLR during Full Power

Execution

0000h u(2) uuuuu u u

Stack Full Reset (STVREN = 1) 0000h u(2) uuuuu 1 u

Stack Underflow Reset

(STVREN = 1)

0000h u(2) uuuuu u 1

Stack Underflow Error (not an

actual Reset, STVREN = 0)

0000h u(2) uuuuu u 1

WDT Time-out during Power

Managed Idle or Sleep modes

PC + 2 u(2) u00uu u u

Interrupt Exit from Power

Managed modes

PC + 2(1) u(2) uu0uu u u

Legend: u = unchanged

Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the

interrupt vector (008h or 0018h).

2: Reset state is ‘1’ for POR and unchanged for all other Resets when software BOR is enabled

(BOREN1:BOREN0 Configuration bits = 01 and SBOREN = 1); otherwise, the Reset state is ‘0’.

PIC18F2585/2680/4585/4680

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

TOSU 2585 2680 4585 4680 ---0 0000 ---0 0000 ---0 uuuu(3)

TOSH 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu(3)

TOSL 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu(3)

STKPTR 2585 2680 4585 4680 00-0 0000 uu-0 0000 uu-u uuuu(3)

PCLATU 2585 2680 4585 4680 ---0 0000 ---0 0000 ---u uuuu

PCLATH 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

PCL 2585 2680 4585 4680 0000 0000 0000 0000 PC + 2(2)

TBLPTRU 2585 2680 4585 4680 --00 0000 --00 0000 --uu uuuu

TBLPTRH 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TBLPTRL 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TABLAT 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

PRODH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

PRODL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

INTCON 2585 2680 4585 4680 0000 000x 0000 000u uuuu uuuu(1)

INTCON2 2585 2680 4585 4680 1111 -1-1 1111 -1-1 uuuu -u-u(1)

INTCON3 2585 2680 4585 4680 11-0 0-00 11-0 0-00 uu-u u-uu(1)

INDF0 2585 2680 4585 4680 N/A N/A N/A

POSTINC0 2585 2680 4585 4680 N/A N/A N/A

POSTDEC0 2585 2680 4585 4680 N/A N/A N/A

PREINC0 2585 2680 4585 4680 N/A N/A N/A

PLUSW0 2585 2680 4585 4680 N/A N/A N/A

FSR0H 2585 2680 4585 4680 ---- 0000 ---- 0000 ---- uuuu

FSR0L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

WREG 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

INDF1 2585 2680 4585 4680 N/A N/A N/A

POSTINC1 2585 2680 4585 4680 N/A N/A N/A

POSTDEC1 2585 2680 4585 4680 N/A N/A N/A

PREINC1 2585 2680 4585 4680 N/A N/A N/A

PLUSW1 2585 2680 4585 4680 N/A N/A N/A

FSR1H 2585 2680 4585 4680 ---- 0000 ---- 0000 ---- uuuu

FSR1L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

BSR 2585 2680 4585 4680 ---- 0000 ---- 0000 ---- uuuu

INDF2 2585 2680 4585 4680 N/A N/A N/A

POSTINC2 2585 2680 4585 4680 N/A N/A N/A

POSTDEC2 2585 2680 4585 4680 N/A N/A N/A

PREINC2 2585 2680 4585 4680 N/A N/A N/A

PLUSW2 2585 2680 4585 4680 N/A N/A N/A

FSR2H 2585 2680 4585 4680 ---- 0000 ---- 0000 ---- uuuu

FSR2L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

STATUS 2585 2680 4585 4680 ---x xxxx ---u uuuu ---u uuuu

TMR0H 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TMR0L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

T0CON 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

OSCCON 2585 2680 4585 4680 0100 q000 0100 00q0 uuuu uuqu

HLVDCON 2585 2680 4585 4680 0-00 0101 0-00 0101 0-uu uuuu

WDTCON 2585 2680 4585 4680 ---- ---0 ---- ---0 ---- ---u

RCON(4) 2585 2680 4585 4680 0q-1 11q0 0q-q qquu uq-u qquu

TMR1H 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TMR1L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

T1CON 2585 2680 4585 4680 0000 0000 u0uu uuuu uuuu uuuu

TMR2 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

PR2 2585 2680 4585 4680 1111 1111 1111 1111 1111 1111

T2CON 2585 2680 4585 4680 -000 0000 -000 0000 -uuu uuuu

SSPBUF 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

SSPADD 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

SSPSTAT 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

SSPCON1 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

SSPCON2 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

ADRESH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

ADRESL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

ADCON0 2585 2680 4585 4680 --00 0000 --00 0000 --uu uuuu

ADCON1 2585 2680 4585 4680 --00 0qqq --00 0qqq --uu uuuu

ADCON2 2585 2680 4585 4680 0-00 0000 0-00 0000 u-uu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

CCPR1H 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

CCPR1L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

CCP1CON 2585 2680 4585 4680 --00 0000 --00 0000 --uu uuuu

ECCPR1H 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

ECCPR1L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

ECCP1CON 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

BAUDCON 2585 2680 4585 4680 01-0 0-00 01-0 0-00 --uu uuuu

ECCP1DEL 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

ECCP1AS 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

CVRCON 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

CMCON 2585 2680 4585 4680 0000 0111 0000 0111 uuuu uuuu

TMR3H 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TMR3L 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

T3CON 2585 2680 4585 4680 0000 0000 uuuu uuuu uuuu uuuu

SPBRGH 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

SPBRG 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RCREG 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TXREG 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TXSTA 2585 2680 4585 4680 0000 0010 0000 0010 uuuu uuuu

RCSTA 2585 2680 4585 4680 0000 000x 0000 000x uuuu uuuu

EEADRH 2585 2680 4585 4680 ---- --00 ---- --00 ---- --uu

EEADR 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

EEDATA 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

EECON2 2585 2680 4585 4680 0000 0000 0000 0000 0000 0000

EECON1 2585 2680 4585 4680 xx-0 x000 uu-0 u000 uu-0 u000

IPR3 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

PIR3 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

PIE3 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

IPR2 2585 2680 4585 4680 11-1 1111 11-1 1111 uu-u uuuu

2585 2680 4585 4680 1--1 111- 1--1 111- u--u uuu-

PIR2 2585 2680 4585 4680 00-0 0000 00-0 0000 uu-u uuuu(1)

2585 2680 4585 4680 0--0 000- 0--0 000- u--u uuu-(1)

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

PIE2 2585 2680 4585 4680 00-0 0000 00-0 0000 uu-u uuuu

2585 2680 4585 4680 0--0 000- 0--0 000- u--u uuu-

IPR1 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

2585 2680 4585 4680 -111 1111 -111 1111 -uuu uuuu

PIR1 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu(1)

2585 2680 4585 4680 -000 0000 -000 0000 -uuu uuuu

PIE1 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

2585 2680 4585 4680 -000 0000 -000 0000 -uuu uuuu

OSCTUNE 2585 2680 4585 4680 --00 0000 --00 0000 --uu uuuu

TRISE 2585 2680 4585 4680 0000 -111 0000 -111 uuuu -uuu

TRISD 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

TRISC 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

TRISB 2585 2680 4585 4680 1111 1111 1111 1111 uuuu uuuu

TRISA(5) 2585 2680 4585 4680 1111 1111(5) 1111 1111(5) uuuu uuuu(5)

LATE 2585 2680 4585 4680 ---- -xxx ---- -uuu ---- -uuu

LATD 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

LATC 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

LATB 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

LATA(5) 2585 2680 4585 4680 xxxx xxxx(5) uuuu uuuu(5) uuuu uuuu(5)

PORTE 2585 2680 4585 4680 ---- x000 ---- x000 ---- uuuu

PORTD 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

PORTC 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

PORTB 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

PORTA(5) 2585 2680 4585 4680 xx0x 0000(5) uu0u 0000(5) uuuu uuuu(5)

ECANCON 2585 2680 4585 4680 0001 0000 0001 0000 uuuu uuuu

TXERRCNT 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXERRCNT 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

COMSTAT 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

CIOCON 2585 2680 4585 4680 --00 ---- --00 ---- --uu ----

BRGCON3 2585 2680 4585 4680 00-- -000 00-- -000 uu-- -uuu

BRGCON2 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

BRGCON1 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

CANCON 2585 2680 4585 4680 1000 000- 1000 000- uuuu uuu-

CANSTAT 2585 2680 4585 4680 100- 000- 100- 000- uuu- uuu-

RXB0D7 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D6 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D5 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D4 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D3 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D2 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D1 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0D0 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0DLC 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

RXB0EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0SIDL 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

RXB0SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB0CON 2585 2680 4585 4680 000- 0000 000- 0000 uuu- uuuu

RXB1D7 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D6 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D5 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D4 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D3 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D2 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D1 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1D0 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1DLC 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

RXB1EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1SIDL 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

RXB1SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXB1CON 2585 2680 4585 4680 000- 0000 000- 0000 uuu- uuuu

TXB0D7 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D6 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

TXB0D5 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D4 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D3 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D2 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D1 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0D0 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0DLC 2585 2680 4585 4680 -x-- xxxx -u-- uuuu -u-- uuuu

TXB0EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

TXB0SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

TXB0SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB0CON 2585 2680 4585 4680 0000 0-00 0000 0-00 uuuu u-uu

TXB1D7 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D6 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D5 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D4 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D3 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D2 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D1 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1D0 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1DLC 2585 2680 4585 4680 -x-- xxxx -u-- uuuu -u-- uuuu

TXB1EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB1SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- uu-u

TXB1SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

TXB1CON 2585 2680 4585 4680 0000 0-00 0000 0-00 uuuu u-uu

TXB2D7 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D6 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D5 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D4 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D3 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D2 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

TXB2D1 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2D0 2585 2680 4585 4680 xxxx xxxx uuuu uuuu 0uuu uuuu

TXB2DLC 2585 2680 4585 4680 -x-- xxxx -u-- uuuu -u-- uuuu

TXB2EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB2EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TXB2SIDL 2585 2680 4585 4680 xxxx x-xx uuuu u-uu -uuu uuuu

TXB2SIDH 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

TXB2CON 2585 2680 4585 4680 0000 0-00 0000 0-00 uuuu u-uu

RXM1EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXM1EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXM1SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXM1SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXM0EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXM0EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXM0SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXM0SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF5EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF5EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF5SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF5SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF4EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF4EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF4SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF4SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF3EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF3EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF3SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF3SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF2EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF2EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF2SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF2SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

RXF1EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF1EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF1SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF1SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF0EIDL 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF0EIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF0SIDL 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF0SIDH 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B5EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B5SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B5SIDH(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B5CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

B4D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B4EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

B4EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B4SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B4CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

B3D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B3EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B3SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B3CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

B2D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B2EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B2SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B2SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

B2CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

B1D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B1EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B1SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B1CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

B0D7(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D6(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D5(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D4(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D3(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D2(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D1(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0D0(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0DLC(6) 2585 2680 4585 4680 -xxx xxxx -uuu uuuu -uuu uuuu

B0EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0SIDL(6) 2585 2680 4585 4680 xxxx x-xx uuuu u-uu uuuu u-uu

B0SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

B0CON(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TXBIE(6) 2585 2680 4585 4680 ---0 00-- ---u uu-- ---u uu--

BIE0(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

BSEL0(6) 2585 2680 4585 4680 0000 00-- 0000 00-- uuuu uu--

MSEL3(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

MSEL2(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

MSEL1(6) 2585 2680 4585 4680 0000 0101 0000 0101 uuuu uuuu

MSEL0(6) 2585 2680 4585 4680 0101 0000 0101 0000 uuuu uuuu

SDFLC(6) 2585 2680 4585 4680 ---0 0000 ---0 0000 -u-- uuuu

RXFCON1(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFCON0(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON7(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON6(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON5(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON4(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON3(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXFBCON2(6) 2585 2680 4585 4680 0001 0001 0001 0001 uuuu uuuu

RXFBCON1(6) 2585 2680 4585 4680 0001 0001 0001 0001 uuuu uuuu

RXFBCON0(6) 2585 2680 4585 4680 0000 0000 0000 0000 uuuu uuuu

RXF15EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF15EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF15SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF15SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF14EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF14EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF14SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF14SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF13EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF13EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF13SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF13SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF12EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF12EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF12SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

RXF12SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF11EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF11EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF11SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu uuu- u-uu

RXF11SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu uuuu uuuu

RXF10EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF10EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF10SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu -uuu uuuu

RXF10SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF9EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF9EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF9SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu -uuu uuuu

RXF9SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF8EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF8EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF8SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu -uuu uuuu

RXF8SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF7EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF7EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF7SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu -uuu uuuu

RXF7SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF6EIDL(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF6EIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

RXF6SIDL(6) 2585 2680 4585 4680 xxx- x-xx uuu- u-uu -uuu uuuu

RXF6SIDH(6) 2585 2680 4585 4680 xxxx xxxx uuuu uuuu -uuu uuuu

TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED)

Brown-out Reset

MCLR Resets,

WDT Reset,

RESET Instruction,

Stack Resets

Wake-up via WDT

or Interrupt

Legend: u = unchanged, x = unknown, - = unimplemented bit, read as ‘0’, q = value depends on condition.

Shaded cells indicate conditions do not apply for the designated device.

Note 1: One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up).

2: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt

vector (0008h or 0018h).

3: When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are

updated with the current value of the PC. The STKPTR is modified to point to the next location in the

hardware stack.

4: See Table 4-3 for Reset value for specific condition.

5: Bits 6 and 7 of PORTA, LATA and TRISA are enabled, depending on the oscillator mode selected. When

not enabled as PORTA pins, they are disabled and read ‘0’.

6: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.

PIC18F2585/2680/4585/4680

5.0 MEMORY ORGANIZATION

There are three types of memory in PIC18 Enhanced

microcontroller devices:

• Program Memory

• Data RAM

• Data EEPROM

As Harvard architecture devices, the data and program

memories use separate busses; this allows for con-

current access of the two memory spaces. The data

EEPROM, for practical purposes, can be regarded as

a peripheral device, since it is addressed and accessed

through a set of control registers.

Additional detailed information on the operation of the

Flash program memory is provided in Section 6.0

“Flash Program Memory”. Data EEPROM is

discussed separately in Section 7.0 “Data EEPROM

Memory”.

5.1 Program Memory Organization

PIC18 microcontrollers implement a 21-bit program

counter, which is capable of addressing a 2-Mbyte

program memory space. Accessing a location between

the upper boundary of the physically implemented

memory and the 2-Mbyte address will return all ‘0’s (a

NOP instruction).

The PIC18F2585 and PIC18F4585 each have

48 Kbytes of Flash memory and can store up to 24,576

single-word instructions. The PIC18F2680 and

PIC18F4680 each have 64 Kbytes of Flash memory

and can store up to 32,768 single-word instructions.

PIC18 devices have two interrupt vectors. The Reset

vector address is at 0000h and the interrupt vector

addresses are at 0008h and 0018h.

The program memory maps for PIC18FX585 and

PIC18FX680 devices are shown in Figure 5-1.

FIGURE 5-1: PROGRAM MEMORY MAP AND STACK FOR

PIC18F2585/2680/4585/4680 DEVICES

PC<20:0>

Stack Level 1

•

Stack Level 31

Reset Vector

Low Priority Interrupt Vector

•

CALL,RCALL,RETURN

RETFIE,RETLW

0000h

0018h

On-Chip

Program Memory

High Priority Interrupt Vector 0008h

User Memory Space

1FFFFFh

C000h

BFFFh

Read ‘0’

200000h

PC<20:0>

Stack Level 1

•

Stack Level 31

Reset Vector

Low Priority Interrupt Vector

•

CALL,RCALL,RETURN

RETFIE,RETLW

0000h

0018h

10000h

FFFFh

On-Chip

Program Memory

High Priority Interrupt Vector 0008h

User Memory Space

Read ‘0’

1FFFFFh

200000h

PIC18X585 PIC18FX680

PIC18F2585/2680/4585/4680

5.1.1 PROGRAM COUNTER

The Program Counter (PC) specifies the address of the

instruction to fetch for execution. The PC is 21 bits wide

and is contained in three separate 8-bit registers. The

low byte, known as the PCL register, is both readable

and writable. The high byte, or PCH register, contains

the PC<15:8> bits; it is not directly readable or writable.

Updates to the PCH register are performed through the

PCLATH register. The upper byte is called PCU. This

directly readable or writable. Updates to the PCU

The contents of PCLATH and PCLATU are transferred

to the program counter by any operation that writes

PCL. Similarly, the upper two bytes of the program

counter are transferred to PCLATH and PCLATU by an

operation that reads PCL. This is useful for computed

offsets to the PC (see Section 5.1.4.1 “Computed

GOTO”).

The PC addresses bytes in the program memory. To

prevent the PC from becoming misaligned with word

instructions, the Least Significant bit of PCL is fixed to

a value of ‘0’. The PC increments by 2 to address

sequential instructions in the program memory.

The CALL, RCALL and GOTO program branch

instructions write to the program counter directly. For

these instructions, the contents of PCLATH and

PCLATU are not transferred to the program counter.

5.1.2 RETURN ADDRESS STACK

The return address stack allows any combination of up

to 31 program calls and interrupts to occur. The PC is

pushed onto the stack when a CALL or RCALL instruc-

tion is executed or an interrupt is Acknowledged. The

PC value is pulled off the stack on a RETURN, RETLW

or a RETFIE instruction. PCLATU and PCLATH are not

affected by any of the RETURN or CALL instructions.

The stack operates as a 31-word by 21-bit RAM and a

5-bit Stack Pointer, STKPTR. The stack space is not

part of either program or data space. The Stack Pointer

is readable and writable and the address on the top of

the stack is readable and writable through the

top-of-stack Special File Registers. Data can also be

pushed to, or popped from the stack, using these

registers.

A CALL type instruction causes a push onto the stack;

the Stack Pointer is first incremented and the location

pointed to by the Stack Pointer is written with the

contents of the PC (already pointing to the instruction

following the CALL). A RETURN type instruction causes

a pop from the stack; the contents of the location

pointed to by the STKPTR are transferred to the PC

and then the Stack Pointer is decremented.

The Stack Pointer is initialized to ‘00000’ after all

Resets. There is no RAM associated with the location

corresponding to a Stack Pointer value of ‘00000’; this

is only a Reset value. Status bits indicate if the stack is

full or has overflowed or has underflowed.

5.1.2.1 Top-of-Stack Access

Only the top of the return address stack (TOS) is

readable and writable. A set of three registers,

TOSU:TOSH:TOSL, hold the contents of the stack loca-

tion pointed to by the STKPTR register (Figure 5-2). This

allows users to implement a software stack if necessary.

After a CALL, RCALL or interrupt, the software can read

the pushed value by reading the TOSU:TOSH:TOSL

registers. These values can be placed on a user defined

software stack. At return time, the software can return

these values to TOSU:TOSH:TOSL and do a return.

The user must disable the global interrupt enable bits

while accessing the stack to prevent inadvertent stack

corruption.

FIGURE 5-2: RETURN ADDRESS STACK AND ASSOCIATED REGISTERS

00011

001A34h

11111

11110

11101

00010

00001

00000

00010

Return Address Stack <20:0>

To p - o f - St a c k

000D58h

TOSLTOSHTOSU

34h1Ah00h

STKPTR<4:0>

Top-of-Stack Registers Stack Pointer

PIC18F2585/2680/4585/4680

5.1.2.2 Return Stack Pointer (STKPTR)

The STKPTR register (Register 5-1) contains the Stack

Pointer value, the STKFUL (Stack Full) status bit and

the STKUNF (Stack Underflow) status bits. The value

of the Stack Pointer can be 0 through 31. The Stack

Pointer increments before values are pushed onto the

stack and decrements after values are popped off the

stack. On Reset, the Stack Pointer value will be zero.

The user may read and write the Stack Pointer value.

This feature can be used by a Real-Time Operating

System (RTOS) for return stack maintenance.

After the PC is pushed onto the stack 31 times (without

popping any values off the stack), the STKFUL bit is

set. The STKFUL bit is cleared by software or by a

POR.

The action that takes place when the stack becomes

full depends on the state of the STVREN (Stack Over-

flow Reset Enable) Configuration bit. (Refer to

Section 24.1 “Configuration Bits” for a description of

the device Configuration bits.) If STVREN is set

(default), the 31st push will push the (PC + 2) value

onto the stack, set the STKFUL bit and reset the

device. The STKFUL bit will remain set and the Stack

Pointer will be set to zero.

If STVREN is cleared, the STKFUL bit will be set on the

31st push and the Stack Pointer will increment to 31.

Any additional pushes will not overwrite the 31st push

and STKPTR will remain at 31.

When the stack has been popped enough times to

unload the stack, the next pop will return a value of zero

to the PC and sets the STKUNF bit, while the Stack

Pointer remains at zero. The STKUNF bit will remain

set until cleared by software or until a POR occurs.

5.1.2.3 PUSH and POP Instructions

Since the Top-of-Stack is readable and writable, the

ability to push values onto the stack and pull values off

the stack without disturbing normal program execution

is a desirable feature. The PIC18 instruction set

includes two instructions, PUSH and POP, that permit

the TOS to be manipulated under software control.

TOSU, TOSH and TOSL can be modified to place data

or a return address on the stack.

The PUSH instruction places the current PC value onto

the stack. This increments the Stack Pointer and loads

the current PC value onto the stack.

The POP instruction discards the current TOS by decre-

menting the Stack Pointer. The previous value pushed

onto the stack then becomes the TOS value.

Note: Returning a value of zero to the PC on an

underflow has the effect of vectoring the

program to the Reset vector, where the

stack conditions can be verified and

appropriate actions can be taken. This is

not the same as a Reset, as the contents

of the SFRs are not affected.

R/C-0 R/C-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

STKFUL(1) STKUNF(1) — SP4 SP3 SP2 SP1 SP0

bit 7 bit 0

bit 7 STKFUL: Stack Full Flag bit(1)

1 = Stack became full or overflowed

0 = Stack has not become full or overflowed

bit 6 STKUNF: Stack Underflow Flag bit(1)

1 = Stack underflow occurred

0 = Stack underflow did not occur

bit 5 Unimplemented: Read as ‘0’

bit 4-0 SP4:SP0: Stack Pointer Location bits

Note 1: Bit 7 and bit 6 are cleared by user software or by a POR.

Legend:

R = Readable bit W = Writable bit U = Unimplemented C = Clearable only bit

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

5.1.2.4 Stack Full and Underflow Resets

Device Resets on stack overflow and stack underflow

conditions are enabled by setting the STVREN bit in

Configuration Register 4L. When STVREN is set, a full

or underflow will set the appropriate STKFUL or

STKUNF bit and then cause a device Reset. When

STVREN is cleared, a full or underflow condition will set

the appropriate STKFUL or STKUNF bit, but not cause

a device Reset. The STKFUL or STKUNF bits are

cleared by the user software or a Power-on Reset.

5.1.3 FAST REGISTER STACK

A fast register stack is provided for the STATUS,

WREG and BSR registers, to provide a “fast return”

option for interrupts. Each stack is only one level deep

and is neither readable nor writable. It is loaded with the

current value of the corresponding register when the

processor vectors for an interrupt. All interrupt sources

will push values into the stack registers. The values in

the registers are then loaded back into their associated

registers, if the RETFIE, FAST instruction is used to

return from the interrupt.

If both low and high priority interrupts are enabled, the

stack registers cannot be used reliably to return from

low priority interrupts. If a high priority interrupt occurs

while servicing a low priority interrupt, the stack register

values stored by the low priority interrupt will be

overwritten. In these cases, users must save the key

registers in software during a low priority interrupt.

If interrupt priority is not used, all interrupts may use the

fast register stack for returns from interrupt. If no inter-

rupts are used, the fast register stack can be used to

restore the STATUS, WREG and BSR registers at the

end of a subroutine call. To use the fast register stack

for a subroutine call, a CALL label, FAST instruction

must be executed to save the STATUS, WREG and

BSR registers to the fast register stack. A

RETURN, FAST instruction is then executed to restore

these registers from the fast register stack.

Example 5-1 shows a source code example that uses

the fast register stack during a subroutine call and

return.

EXAMPLE 5-1: FAST REGISTER STACK

CODE EXAMPLE

5.1.4 LOOK-UP TABLES IN PROGRAM

MEMORY

There may be programming situations that require the

creation of data structures, or look-up tables, in

program memory. For PIC18 devices, look-up tables

can be implemented in two ways:

• Computed GOTO

• Table Reads

5.1.4.1 Computed GOTO

A computed GOTO is accomplished by adding an offset

to the program counter. An example is shown in

Example 5-2.

A look-up table can be formed with an ADDWF PCL

instruction and a group of RETLW nn instructions. The

W register is loaded with an offset into the table before

executing a CALL to that table. The first instruction of

the called routine is the ADDWF PCL instruction. The

next instruction executed will be one of the RETLW nn

instructions, that returns the value ‘nn’ to the calling

function.

The offset value (in WREG) specifies the number of

bytes that the program counter should advance and

should be multiples of 2 (LSb = 0).

In this method, only one data byte may be stored in

each instruction location and room on the return

address stack is required.

EXAMPLE 5-2: COMPUTED GOTO USING

AN OFFSET VALUE

5.1.4.2 Table Reads and Table Writes

A better method of storing data in program memory

allows two bytes of data to be stored in each instruction

location.

Look-up table data may be stored two bytes per

program word by using table reads and writes. The

Table Pointer (TBLPTR) register specifies the byte

address and the Table Latch (TABLAT) register

contains the data that is read from or written to program

memory. Data is transferred to or from program

memory one byte at a time.

Table read and table write operations are discussed

further in Section 6.1 “Table Reads and Table

Writes”.

CALL SUB1, FAST ;STATUS, WREG, BSR

;SAVED IN FAST REGISTER

;STACK

•

SUB1 •

•

RETURN, FAST ;RESTORE VALUES SAVED

;IN FAST REGISTER STACK

MOVF OFFSET, W

CALL TABLE

ORG nn00h

TABLE ADDWF PCL

RETLW nnh

PIC18F2585/2680/4585/4680

5.2 PIC18 Instruction Cycle

5.2.1 CLOCKING SCHEME

The microcontroller clock input, whether from an inter-

nal or external source, is internally divided by four to

generate four non-overlapping quadrature clocks (Q1,

Q2, Q3 and Q4). Internally, the Program Counter (PC)

is incremented on every Q1; the instruction is fetched

from the program memory and latched into the Instruc-

tion Register (IR) during Q4. The instruction is decoded

and executed during the following Q1 through Q4. The

clocks and instruction execution flow are shown in

Figure 5-3.

5.2.2 INSTRUCTION FLOW/PIPELINING

An “Instruction Cycle” consists of four Q cycles: Q1

through Q4. The instruction fetch and execute are pipe-

lined in such a manner that a fetch takes one instruction

cycle, while the decode and execute take another

instruction cycle. However, due to the pipelining, each

instruction effectively executes in one cycle. If an

instruction causes the program counter to change (e.g.,

GOTO), then two cycles are required to complete the

instruction (Example 5-3).

A fetch cycle begins with the program counter

incrementing in Q1.

In the execution cycle, the fetched instruction is latched

into the Instruction Register (IR) in cycle Q1. This

instruction is then decoded and executed during the

Q2, Q3 and Q4 cycles. Data memory is read during Q2

(operand read) and written during Q4 (destination

write).

FIGURE 5-3: CLOCK/INSTRUCTION CYCLE

EXAMPLE 5-3: INSTRUCTION PIPELINE FLOW

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

OSC1

OSC2/CLKO

(RC mode)

PC PC + 2 PC + 4

Fetch INST (PC)

Execute INST (PC – 2)

Fetch INST (PC + 2)

Execute INST (PC)

Fetch INST (PC + 4)

Execute INST (PC + 2)

Internal

Phase

Clock

Note: All instructions are single cycle, except for any program branches. These take two cycles since the

fetch instruction is “flushed” from the pipeline while the new instruction is being fetched and then

executed.

TCY0TCY1TCY2TCY3TCY4TCY5

1. MOVLW 55h Fetch 1 Execute 1

2. MOVWF PORTB Fetch 2 Execute 2

3. BRA SUB_1 Fetch 3 Execute 3

4. BSF PORTA, BIT3 (Forced NOP) Fetch 4 Flush (NOP)

5. Instruction @ address SUB_1 Fetch SUB_1 Execute SUB_1

PIC18F2585/2680/4585/4680

5.2.3 INSTRUCTIONS IN PROGRAM

MEMORY

The program memory is addressed in bytes. Instruc-

tions are stored as two bytes or four bytes in program

memory. The Least Significant Byte of an instruction

word is always stored in a program memory location

with an even address (LSB = 0). To maintain alignment

with instruction boundaries, the PC increments in steps

of 2 and the LSB will always read ‘0’ (see Section 5.1.1

“Program Counter”).

Figure 5-4 shows an example of how instruction words

are stored in the program memory.

The CALL and GOTO instructions have the absolute

program memory address embedded into the instruc-

tion. Since instructions are always stored on word

boundaries, the data contained in the instruction is a

word address. The word address is written to PC<20:1>,

which accesses the desired byte address in program

memory. Instruction #2 in Figure 5-4 shows how the

instruction GOTO 0006h is encoded in the program

memory. Program branch instructions, which encode a

relative address offset, operate in the same manner. The

offset value stored in a branch instruction represents the

number of single-word instructions that the PC will be

offset by. Section 25.0 “Instruction Set Summary”

provides further details of the instruction set.

FIGURE 5-4: INSTRUCTIONS IN PROGRAM MEMORY

5.2.4 TWO-WORD INSTRUCTIONS

The standard PIC18 instruction set has four two-word

instructions: CALL, MOVFF, GOTO and LSFR. In all

cases, the second word of the instructions always has

‘1111’ as its four Most Significant bits; the other 12 bits

are literal data, usually a data memory address.

The use of ‘1111’ in the 4 MSbs of an instruction

specifies a special form of NOP. If the instruction is

executed in proper sequence – immediately after the

first word – the data in the second word is accessed

and used by the instruction sequence. If the first word

is skipped for some reason and the second word is

executed by itself, a NOP is executed instead. This is

necessary for cases when the two-word instruction is

preceded by a conditional instruction that changes the

PC. Example 5-4 shows how this works.

EXAMPLE 5-4: TWO-WORD INSTRUCTIONS

Word Address

LSB = 1LSB = 0↓

Program Memory

Byte Locations →

000000h

000002h

000004h

000006h

Instruction 1: MOVLW 055h 0Fh 55h 000008h

Instruction 2: GOTO 0006h EFh 03h 00000Ah

F0h 00h 00000Ch

Instruction 3: MOVFF 123h, 456h C1h 23h 00000Eh

F4h 56h 000010h

000012h

000014h

Note: See Section 5.5 “Program Memory and

the Extended Instruction Set” for

information on two-word instructions in the

extended instruction set.

CASE 1:

Object Code Source Code

0110 0110 0000 0000 TSTFSZ REG1 ; is RAM location 0?

1100 0001 0010 0011 MOVFF REG1, REG2 ; No, skip this word

1111 0100 0101 0110 ; Execute this word as a NOP

0010 0100 0000 0000 ADDWF REG3 ; continue code

CASE 2:

Object Code Source Code

0110 0110 0000 0000 TSTFSZ REG1 ; is RAM location 0?

1100 0001 0010 0011 MOVFF REG1, REG2 ; Yes, execute this word

1111 0100 0101 0110 ; 2nd word of instruction

0010 0100 0000 0000 ADDWF REG3 ; continue code

PIC18F2585/2680/4585/4680

5.3 Data Memory Organization

The data memory in PIC18 devices is implemented as

static RAM. Each register in the data memory has a

12-bit address, allowing up to 4096 bytes of data

memory. The memory space is divided into as many as

16 banks that contain 256 bytes each;

PIC18F2585/2680/4585/4680 devices implement all

16 banks. Figure 5-5 shows the data memory

organization for the PIC18F2585/2680/4585/4680

devices.

The data memory contains Special Function Registers

(SFRs) and General Purpose Registers (GPRs). The

SFRs are used for control and status of the controller

and peripheral functions, while GPRs are used for data

storage and scratchpad operations in the user’s

application. Any read of an unimplemented location will

read as ‘0’s.

The instruction set and architecture allow operations

across all banks. The entire data memory may be

accessed by Direct, Indirect or Indexed Addressing

modes. Addressing modes are discussed later in this

subsection.

To ensure that commonly used registers (SFRs and

select GPRs) can be accessed in a single cycle, PIC18

devices implement an Access Bank. This is a 256-byte

memory space that provides fast access to SFRs and

the lower portion of GPR Bank 0 without using the

BSR. Section 5.3.2 “Access Bank” provides a

detailed description of the Access RAM.

5.3.1 BANK SELECT REGISTER (BSR)

Large areas of data memory require an efficient

addressing scheme to make rapid access to any

address possible. Ideally, this means that an entire

address does not need to be provided for each read or

write operation. For PIC18 devices, this is accom-

plished with a RAM banking scheme. This divides the

memory space into 16 contiguous banks of 256 bytes.

Depending on the instruction, each location can be

addressed directly by its full 12-bit address, or an 8-bit

low-order address and a 4-bit bank pointer.

Most instructions in the PIC18 instruction set make use

of the bank pointer, known as the Bank Select Register

(BSR). This SFR holds the 4 Most Significant bits of a

location’s address; the instruction itself includes the

8 Least Significant bits. Only the four lower bits of the

BSR are implemented (BSR3:BSR0). The upper four

bits are unused; they will always read ‘0’ and cannot be

written to. The BSR can be loaded directly by using the

MOVLB instruction.

The value of the BSR indicates the bank in data mem-

ory; the 8 bits in the instruction show the location in the

bank and can be thought of as an offset from the bank’s

lower boundary. The relationship between the BSR’s

value and the bank division in data memory is shown in

Figure 5-6.

Since up to 16 registers may share the same low-order

address, the user must always be careful to ensure that

the proper bank is selected before performing a data

read or write. For example, writing what should be

program data to an 8-bit address of F9h while the BSR

is 0Fh, will end up resetting the program counter.

While any bank can be selected, only those banks that

are actually implemented can be read or written to.

Writes to unimplemented banks are ignored, while

reads from unimplemented banks will return ‘0’s. Even

so, the STATUS register will still be affected as if the

operation was successful. The data memory map in

Figure 5-5 indicates which banks are implemented.

In the core PIC18 instruction set, only the MOVFF

instruction fully specifies the 12-bit address of the

source and target registers. This instruction ignores the

BSR completely when it executes. All other instructions

include only the low-order address as an operand and

must use either the BSR or the Access Bank to locate

their target registers.

Note: The operation of some aspects of data

memory are changed when the PIC18

extended instruction set is enabled. See

Section 5.6 “Data Memory and the

Extended Instruction Set” for more

information.

PIC18F2585/2680/4585/4680

FIGURE 5-5: DATA MEMORY MAP FOR PIC18F2585/2680/4585/4680 DEVICES

Bank 0

Bank 1

Bank 14

Bank 15

Data Memory Map

BSR<3:0>

= 0000

= 0001

= 1111

060h

05Fh

F60h

FFFh

00h

5Fh

60h

FFh

Access Bank

When a = 0:

The BSR is ignored and the

Access Bank is used.

The first 128 bytes are

general purpose RAM

(from Bank 0).

The second 128 bytes are

Special Function Registers

(from Bank 15).

When a = 1:

The BSR specifies the Bank

used by the instruction.

F5Fh

F00h

EFFh

1FFh

100h

0FFh

000h

Access RAM

FFh

00h

FFh

00h

FFh

00h

GPR

SFR

CAN SFRs

Access RAM High

Access RAM Low

Bank 2

= 0110

= 0010

(SFRs)

2FFh

200h

3FFh

300h

4FFh

400h

5FFh

500h

6FFh

600h

7FFh

700h

8FFh

800h

9FFh

900h

AFFh

A00h

BFFh

B00h

CFFh

C00h

DFFh

D00h

E00h

Bank 3

Bank 4

Bank 5

Bank 6

Bank 7

Bank 8

Bank 9

Bank 10

Bank 11

Bank 12

Bank 13

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

GPR

CAN SFRs

FFh

00h

= 0011

= 0100

= 0101

= 0111

= 1000

= 1001

= 1010

= 1011

= 1100

= 1101

= 1110

PIC18F2585/2680/4585/4680

FIGURE 5-6: USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING)

5.3.2 ACCESS BANK

While the use of the BSR with an embedded 8-bit

address allows users to address the entire range of

data memory, it also means that the user must always

ensure that the correct bank is selected. Otherwise,

data may be read from or written to the wrong location.

This can be disastrous if a GPR is the intended target

of an operation, but an SFR is written to instead.

Verifying and/or changing the BSR for each read or

write to data memory can become very inefficient.

To streamline access for the most commonly used data

memory locations, the data memory is configured with

an Access Bank, which allows users to access a

mapped block of memory without specifying a BSR.

The Access Bank consists of the first 128 bytes of

memory (00h-7Fh) in Bank 0 and the last 128 bytes of

memory (80h-FFh) in Block 15. The lower half is known

as the “Access RAM” and is composed of GPRs. The

upper half is also where the device’s SFRs are

mapped. These two areas are mapped contiguously in

the Access Bank and can be addressed in a linear

fashion by an 8-bit address (Figure 5-5).

The Access Bank is used by core PIC18 instructions

that include the Access RAM bit (the ‘a’ parameter in

the instruction). When ‘a’ is equal to ‘1’, the instruction

uses the BSR and the 8-bit address included in the

opcode for the data memory address. When ‘a’ is ‘0’

however, the instruction is forced to use the Access

Bank address map; the current value of the BSR is

ignored entirely.

Using this “forced” addressing allows the instruction to

operate on a data address in a single cycle, without

updating the BSR first. For 8-bit addresses of 80h and

above, this means that users can evaluate and operate

on SFRs more efficiently. The Access RAM below 80h

is a good place for data values that the user might need

to access rapidly, such as immediate computational

results or common program variables. Access RAM

also allows for faster and more code efficient context

saving and switching of variables.

The mapping of the Access Bank is slightly different

when the extended instruction set is enabled (XINST

Configuration bit = 1). This is discussed in more detail

in Section 5.6.3 “Mapping the Access Bank in

Indexed Literal Offset Mode”.

5.3.3 GENERAL PURPOSE

PIC18 devices may have banked memory in the GPR

area. This is data RAM, which is available for use by all

instructions. GPRs start at the bottom of Bank 0

(address 000h) and grow upwards towards the bottom

of the SFR area. GPRs are not initialized by a

Power-on Reset and are unchanged on all other

Resets.

Note 1: The Access RAM bit of the instruction can be used to force an override of the selected bank (BSR<3:0>) to

the registers of the Access Bank.

2: The MOVFF instruction embeds the entire 12-bit address in the instruction.

Data Memory

Bank Select(2)

From Opcode(2)

0000

000h

100h

200h

300h

F00h

E00h

FFFh

Bank 0

Bank 1

Bank 2

Bank 14

Bank 15

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

00h

FFh

Bank 3

through

Bank 13

0011 11111111

BSR(1)

PIC18F2585/2680/4585/4680

5.3.4 SPECIAL FUNCTION REGISTERS

The Special Function Registers (SFRs) are registers

used by the CPU and peripheral modules for controlling

the desired operation of the device. These registers are

implemented as static RAM. SFRs start at the top of

data memory (FFFh) and extend downward to occupy

the top half of Bank 15 (F80h to FFFh). A list of these

registers is given in Table 5-1 and Table 5-2.

The SFRs can be classified into two sets: those

associated with the “core” device functionality (ALU,

Resets and interrupts) and those related to the

peripheral functions. The reset and interrupt registers

are described in their respective chapters, while the

ALU’s STATUS register is described later in this

section. Registers related to the operation of a

peripheral feature are described in the chapter for that

peripheral.

The SFRs are typically distributed among the

peripherals whose functions they control. Unused SFR

locations are unimplemented and read as ‘0’s.

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES

Address Name Address Name Address Name Address Name

FFFh TOSU FDFh INDF2(3) FBFh CCPR1H F9Fh IPR1

FFEh TOSH FDEh POSTINC2(3) FBEh CCPR1L F9Eh PIR1

FFDh TOSL FDDh POSTDEC2(3) FBDh CCP1CON F9Dh PIE1

FFCh STKPTR FDCh PREINC2(3) FBCh ECCPR1H(1) F9Ch —

FFBh PCLATU FDBh PLUSW2(3) FBBh ECCPR1L(1) F9Bh OSCTUNE

FFAh PCLATH FDAh FSR2H FBAh ECCP1CON(1) F9Ah —

FF9h PCL FD9h FSR2L FB9h — F99h —

FF8h TBLPTRU FD8h STATUS FB8h BAUDCON F98h —

FF7h TBLPTRH FD7h TMR0H FB7h ECCP1DEL F97h —

FF6h TBLPTRL FD6h TMR0L FB6h ECCP1AS(1) F96h TRISE(1)

FF5h TABLAT FD5h T0CON FB5h CVRCON(1) F95h TRISD(1)

FF4h PRODH FD4h — FB4h CMCON F94h TRISC

FF3h PRODL FD3h OSCCON FB3h TMR3H F93h TRISB

FF2h INTCON FD2h HLVDCON FB2h TMR3L F92h TRISA

FF1h INTCON2 FD1h WDTCON FB1h T3CON F91h —

FF0h INTCON3 FD0h RCON FB0h SPBRGH F90h —

FEFh INDF0(3) FCFh TMR1H FAFh SPBRG F8Fh —

FEEh POSTINC0(3) FCEh TMR1L FAEh RCREG F8Eh —

FEDh POSTDEC0(3) FCDh T1CON FADh TXREG F8Dh LATE(1)

FECh PREINC0(3) FCCh TMR2 FACh TXSTA F8Ch LATD(1)

FEBh PLUSW0(3) FCBh PR2 FABh RCSTA F8Bh LATC

FEAh FSR0H FCAh T2CON FAAh EEADRH F8Ah LATB

FE9h FSR0L FC9h SSPBUF FA9h EEADR F89h LATA

FE8h WREG FC8h SSPADD FA8h EEDATA F88h —

FE7h INDF1(3) FC7h SSPSTAT FA7h EECON2(3) F87h —

FE6h POSTINC1(3) FC6h SSPCON1 FA6h EECON1 F86h —

FE5h POSTDEC1(3) FC5h SSPCON2 FA5h IPR3 F85h —

FE4h PREINC1(3) FC4h ADRESH FA4h PIR3 F84h PORTE(1)

FE3h PLUSW1(3) FC3h ADRESL FA3h PIE3 F83h PORTD(1)

FE2h FSR1H FC2h ADCON0 FA2h IPR2 F82h PORTC

FE1h FSR1L FC1h ADCON1 FA1h PIR2 F81h PORTB

FE0h BSR FC0h ADCON2 FA0h PIE2 F80h PORTA

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680

Address Name Address Name Address Name Address Name

F7Fh — F5Fh CANCON_RO0 F3Fh CANCON_RO2 F1Fh RXM1EIDL

F7Eh — F5Eh CANSTAT_RO0 F3Eh CANSTAT_RO2 F1Eh RXM1EIDH

F7Dh — F5Dh RXB1D7 F3Dh TXB1D7 F1Dh RXM1SIDL

F7Ch — F5Ch RXB1D6 F3Ch TXB1D6 F1Ch RXM1SIDH

F7Bh — F5Bh RXB1D5 F3Bh TXB1D5 F1Bh RXM0EIDL

F7Ah — F5Ah RXB1D4 F3Ah TXB1D4 F1Ah RXM0EIDH

F79h — F59h RXB1D3 F39h TXB1D3 F19h RXM0SIDL

F78h — F58h RXB1D2 F38h TXB1D2 F18h RXM0SIDH

F77h ECANCON F57h RXB1D1 F37h TXB1D1 F17h RXF5EIDL

F76h TXERRCNT F56h RXB1D0 F36h TXB1D0 F16h RXF5EIDH

F75h RXERRCNT F55h RXB1DLC F35h TXB1DLC F15h RXF5SIDL

F74h COMSTAT F54h RXB1EIDL F34h TXB1EIDL F14h RXF5SIDH

F73h CIOCON F53h RXB1EIDH F33h TXB1EIDH F13h RXF4EIDL

F72h BRGCON3 F52h RXB1SIDL F32h TXB1SIDL F12h RXF4EIDH

F71h BRGCON2 F51h RXB1SIDH F31h TXB1SIDH F11h RXF4SIDL

F70h BRGCON1 F50h RXB1CON F30h TXB1CON F10h RXF4SIDH

F6Fh CANCON F4Fh CANCON_RO1 F2Fh CANCON_RO3 F0Fh RXF3EIDL

F6Eh CANSTAT F4Eh CANSTAT_RO1 F2Eh CANSTAT_RO3 F0Eh RXF3EIDH

F6Dh RXB0D7 F4DH TXB0D7 F2Dh TXB2D7 F0Dh RXF3SIDL

F6Ch RXB0D6 F4Ch TXB0D6 F2Ch TXB2D6 F0Ch RXF3SIDH

F6Bh RXB0D5 F4Bh TXB0D5 F2Bh TXB2D5 F0Bh RXF2EIDL

F6Ah RXB0D4 F4Ah TXB0D4 F2Ah TXB2D4 F0Ah RXF2EIDH

F69h RXB0D3 F49h TXB0D3 F29h TXB2D3 F09h RXF2SIDL

F68h RXB0D2 F48h TXB0D2 F28h TXB2D2 F08h RXF2SIDH

F67h RXB0D1 F47h TXB0D1 F27h TXB2D1 F07h RXF1EIDL

F66h RXB0D0 F46h TXB0D0 F26h TXB2D0 F06h RXF1EIDH

F65h RXB0DLC F45h TXB0DLC F25h TXB2DLC F05h RXF1SIDL

F64h RXB0EIDL F44h TXB0EIDL F24h TXB2EIDL F04h RXF1SIDH

F63h RXB0EIDH F43h TXB0EIDH F23h TXB2EIDH F03h RXF0EIDL

F62h RXB0SIDL F42h TXB0SIDL F22h TXB2SIDL F02h RXF0EIDH

F61h RXB0SIDH F41h TXB0SIDH F21h TXB2SIDH F01h RXF0SIDL

F60h RXB0CON F40h TXB0CON F20h TXB2CON F00h RXF0SIDH

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES (CONTINUED)

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680

Address Name Address Name Address Name Address Name

EFFh —EDFh—EBFh—E9Fh—

EFEh —EDEh—EBEh—E9Eh—

EFDh —EDDh—EBDh—E9Dh—

EFCh —EDCh—EBCh—E9Ch—

EFBh —EDBh—EBBh—E9Bh—

EFAh —EDAh—EBAh—E9Ah—

EF9h —ED9h—EB9h— E99h —

EF8h —ED8h—EB8h— E98h —

EF7h —ED7h—EB7h— E97h —

EF6h —ED6h—EB6h— E96h —

EF5h —ED5h—EB5h— E95h —

EF4h —ED4h—EB4h— E94h —

EF3h —ED3h—EB3h— E93h —

EF2h —ED2h—EB2h— E92h —

EF1h —ED1h—EB1h— E91h —

EF0h —ED0h—EB0h— E90h —

EEFh —ECFh—EAFh—E8Fh—

EEEh —ECEh—EAEh—E8Eh—

EEDh —ECDh—EADh—E8Dh—

EECh —ECCh—EACh—E8Ch—

EEBh —ECBh—EABh—E8Bh—

EEAh —ECAh—EAAh—E8Ah—

EE9h —EC9h—EA9h— E89h —

EE8h —EC8h—EA8h— E88h —

EE7h —EC7h—EA7h— E87h —

EE6h —EC6h—EA6h— E86h —

EE5h —EC5h—EA5h— E85h —

EE4h —EC4h—EA4h— E84h —

EE3h —EC3h—EA3h— E83h —

EE2h —EC2h—EA2h— E82h —

EE1h —EC1h—EA1h— E81h —

EE0h —EC0h—EA0h— E80h —

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES (CONTINUED)

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680

Address Name Address Name Address Name Address Name

E7Fh CANCON_RO4 E6Fh CANCON_RO5 E5Fh CANCON_RO6 E4Fh CANCON_RO7

E7Eh CANSTAT_RO4 E6Eh CANSTAT_RO5 E5Eh CANSTAT_RO6 E4Eh CANSTAT_RO7

E7Dh B5D7(2) E6Dh B4D7(2) E5Dh B3D7(2) E4Dh B2D7(2)

E7Ch B5D6(2) E6Ch B4D6(2) E5Ch B3D6(2) E4Ch B2D6(2)

E7Bh B5D5(2) E6Bh B4D5(2) E5Bh B3D5(2) E4Bh B2D5(2)

E7Ah B5D4(2) E6Ah B4D4(2) E5Ah B3D4(2) E4Ah B2D4(2)

E79h B5D3(2) E69h B4D3(2) E59h B3D3(2) E49h B2D3(2)

E78h B5D2(2) E68h B4D2(2) E58h B3D2(2) E48h B2D2(2)

E77h B5D1(2) E67h B4D1(2) E57h B3D1(2) E47h B2D1(2)

E76h B5D0(2) E66h B4D0(2) E56h B3D0(2) E46h B2D0(2)

E75h B5DLC(2) E65h B4DLC(2) E55h B3DLC(2) E45h B2DLC(2)

E74h B5EIDL(2) E64h B4EIDL(2) E54h B3EIDL(2) E44h B2EIDL(2)

E73h B5EIDH(2) E63h B4EIDH(2) E53h B3EIDH(2) E43h B2EIDH(2)

E72h B5SIDL(2) E62h B4SIDL(2) E52h B3SIDL(2) E42h B2SIDL(2)

E71h B5SIDH(2) E61h B4SIDH(2) E51h B3SIDH(2) E41h B2SIDH(2)

E70h B5CON(2) E60h B4CON(2) E50h B3CON(2) E40h B2CON(2)

E3Fh CANCON_RO8 E2Fh CANCON_RO9 E1Fh —E0Fh—

E3Eh CANSTAT_RO8 E2Eh CANSTAT_RO9 E1Eh —E0Eh—

E3Dh B1D7(2) E2Dh B0D7(2) E1Dh —E0Dh—

E3Ch B1D6(2) E2Ch B0D6(2) E1Ch —E0Ch—

E3Bh B1D5(2) E2Bh B0D5(2) E1Bh —E0Bh—

E3Ah B1D4(2) E2Ah B0D4(2) E1Ah —E0Ah—

E39h B1D3(2) E29h B0D3(2) E19h — E09h —

E38h B1D2(2) E28h B0D2(2) E18h — E08h —

E37h B1D1(2) E27h B0D1(2) E17h — E07h —

E36h B1D0(2) E26h B0D0(2) E16h — E06h —

E35h B1DLC(2) E25h B0DLC(2) E15h — E05h —

E34h B1EIDL(2) E24h B0EIDL(2) E14h — E04h —

E33h B1EIDH(2) E23h B0EIDH(2) E13h — E03h —

E32h B1SIDL(2) E22h B0SIDL(2) E12h — E02h —

E31h B1SIDH(2) E21h B0SIDH(2) E11h — E01h —

E30h B1CON(2) E20h B0CON(2) E10h — E00h —

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES (CONTINUED)

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680

Address Name Address Name Address Name Address Name

DFFh — DDFh —DBFh—D9Fh—

DFEh — DDEh —DBEh—D9Eh—

DFDh —DDDh—DBDh—D9Dh—

DFCh TXBIE DDCh —DBCh—D9Ch—

DFBh — DDBh —DBBh—D9Bh—

DFAh BIE0 DDAh —DBAh—D9Ah—

DF9h —DD9h—DB9h— D99h —

DF8h BSEL0 DD8h SDFLC DB8h — D98h —

DF7h —DD7h—DB7h— D97h —

DF6h —DD6h—DB6h— D96h —

DF5h — DD5h RXFCON1 DB5h — D95h —

DF4h — DD4h RXFCON0 DB4h — D94h —

DF3h MSEL3 DD3h —DB3h— D93h RXF15EIDL

DF2h MSEL2 DD2h —DB2h— D92h RXF15EIDH

DF1h MSEL1 DD1h —DB1h— D91h RXF15SIDL

DF0h MSEL0 DD0h —DB0h— D90h RXF15SIDH

DEFh — DCFh —DAFh—D8Fh—

DEEh — DCEh —DAEh—D8Eh—

DEDh —DCDh—DADh—D8Dh—

DECh —DCCh—DACh—D8Ch—

DEBh — DCBh —DABh—D8BhRXF14EIDL

DEAh — DCAh —DAAh— D8Ah RXF14EIDH

DE9h —DC9h—DA9h— D89h RXF14SIDL

DE8h —DC8h—DA8h— D88h RXF14SIDH

DE7h RXFBCON7 DC7h —DA7h— D87h RXF13EIDL

DE6h RXFBCON6 DC6h —DA6h— D86h RXF13EIDH

DE5h RXFBCON5 DC5h —DA5h— D85h RXF13SIDL

DE4h RXFBCON4 DC4h —DA4h— D84h RXF13SIDH

DE3h RXFBCON3 DC3h —DA3h— D83h RXF12EIDL

DE2h RXFBCON2 DC2h —DA2h— D82h RXF12EIDH

DE1h RXFBCON1 DC1h —DA1h— D81h RXF12SIDL

DE0h RXFBCON0 DC0h —DA0h— D80h RXF12SIDH

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES (CONTINUED)

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680

Address Name

D7Fh —

D7Eh —

D7Dh —

D7Ch —

D7Bh RXF11EIDL

D7Ah RXF11EIDH

D79h RXF11SIDL

D78h RXF11SIDH

D77h RXF10EIDL

D76h RXF10EIDH

D75h RXF10SIDL

D74h RXF10SIDH

D73h RXF9EIDL

D72h RXF9EIDH

D71h RXF9SIDL

D70h RXF9SIDH

D6Fh —

D6Eh —

D6Dh —

D6Ch —

D6Bh RXF8EIDL

D6Ah RXF8EIDH

D69h RXF8SIDL

D68h RXF8SIDH

D67h RXF7EIDL

D66h RXF7EIDH

D65h RXF7SIDL

D64h RXF7SIDH

D63h RXF6EIDL

D62h RXF6EIDH

D61h RXF6SIDL

D60h RXF6SIDH

TABLE 5-1: SPECIAL FUNCTION REGISTER MAP FOR

PIC18F2585/2680/4585/4680 DEVICES (CONTINUED)

Note 1: Registers available only on PIC18F4X8X devices; otherwise, the registers read as ‘0’.

2: When any TX_ENn bit in RX_TX_SELn is set, then the corresponding bit in this register has transmit properties.

3: This is not a physical register.

PIC18F2585/2680/4585/4680
DS39625C-page 76 Preliminary © 2007 Microchip Technology Inc.
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
TOSU — — — Top-of-Stack Upper Byte (TOS<20:16>) ---0 0000 49, 62
TOSH Top-of-Stack High Byte (TOS<15:8>) 0000 0000 49, 62
TOSL Top-of-Stack Low Byte (TOS<7:0>) 0000 0000 49, 62
STKPTR STKFUL STKUNF — Return Stack Pointer 00-0 0000 49, 63
PCLATU ——bit 21
(1) Holding Register for PC<20:16> ---0 0000 49, 62
PCLATH Holding Register for PC<15:8> 0000 0000 49, 62
PCL PC Low Byte (PC<7:0>) 0000 0000 49, 62
TBLPTRU —— bit 21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) --00 0000 49, 103
TBLPTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) 0000 0000 49, 103
TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>) 0000 0000 49, 103
TABLAT Program Memory Table Latch 0000 0000 49, 103
PRODH Product Register High Byte xxxx xxxx 49, 111
PRODL Product Register Low Byte xxxx xxxx 49, 111
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 49, 115
INTCON2 RBPU INTEDG0 INTEDG1 INTEDG2 —TMR0IP —RBIP1111 -1-1 49, 116
INTCON3 INT2IP INT1IP — INT2IE INT1IE — INT2IF INT1IF 11-0 0-00 49, 117
INDF0 Uses contents of FSR0 to address data memory – value of FSR0 not changed (not a physical register) N/A 49, 89
POSTINC0 Uses contents of FSR0 to address data memory – value of FSR0 post-incremented (not a physical register) N/A 49, 90
POSTDEC0 Uses contents of FSR0 to address data memory – value of FSR0 post-decremented (not a physical register) N/A 49, 90
PREINC0 Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register) N/A 49, 90
PLUSW0 Uses contents of FSR0 to address data memory – value of FSR0 pre-incremented (not a physical register), 
value of FSR0 offset by W
N/A 49, 90
FSR0H — — — — Indirect Data Memory Address Pointer 0 High ---- xxxx 49, 89
FSR0L Indirect Data Memory Address Pointer 0 Low Byte xxxx xxxx 49, 89
WREG Working Register xxxx xxxx 49
INDF1 Uses contents of FSR1 to address data memory – value of FSR1 not changed (not a physical register) N/A 49, 89
POSTINC1 Uses contents of FSR1 to address data memory – value of FSR1 post-incremented (not a physical register) N/A 49, 90
POSTDEC1 Uses contents of FSR1 to address data memory – value of FSR1 post-decremented (not a physical register) N/A 49, 90
PREINC1 Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register) N/A 49, 90
PLUSW1 Uses contents of FSR1 to address data memory – value of FSR1 pre-incremented (not a physical register), 
value of FSR1 offset by W
N/A 49, 90
FSR1H — — — — Indirect Data Memory Address Pointer 1 High ---- xxxx 49, 89
FSR1L Indirect Data Memory Address Pointer 1 Low Byte xxxx xxxx 49, 89
BSR — — — — Bank Select Register ---- 0000 50, 67
INDF2 Uses contents of FSR2 to address data memory – value of FSR2 not changed (not a physical register) N/A 50, 89
POSTINC2 Uses contents of FSR2 to address data memory – value of FSR2 post-incremented (not a physical register) N/A 50, 90
POSTDEC2 Uses contents of FSR2 to address data memory – value of FSR2 post-decremented (not a physical register) N/A 50, 90
PREINC2 Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register) N/A 50, 90
PLUSW2 Uses contents of FSR2 to address data memory – value of FSR2 pre-incremented (not a physical register), 
value of FSR2 offset by W
N/A 50, 90
FSR2H — — — — Indirect Data Memory Address Pointer 2 High ---- xxxx 50, 89
FSR2L Indirect Data Memory Address Pointer 2 Low Byte xxxx xxxx 50, 89
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 77
PIC18F2585/2680/4585/4680
STATUS — — —NOV Z DC C---x xxxx 50, 87
TMR0H Timer0 Register High Byte 0000 0000 50, 149
TMR0L Timer0 Register Low Byte xxxx xxxx 50, 149
T0CON TMR0ON T08BIT T0CS T0SE PSA T0PS2 T0PS1 T0PS0 1111 1111 50, 149
OSCCON IDLEN IRCF2 IRCF1 IRCF0 OSTS IOFS SCS1 SCS0 0000 q000 30, 50
HLVDCON VDIRMAG — IRVST HLVDEN HLVDL3 HLVDL2 HLVDL1 HLVDL0 0-00 0101 50, 267
WDTCON — — — — — — —SWDTEN--- ---0 50, 353
RCON IPEN SBOREN(2) —RITO PD POR BOR 0q-1 11q0 50, 127
TMR1H Timer1 Register High Byte xxxx xxxx 50, 155
TMR1L Timer1 Register Low Byte 0000 0000 50, 155
T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 50, 151
TMR2 Timer2 Register 1111 1111 50, 158
PR2 Timer2 Period Register -000 0000 50, 155
T2CON — T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 50, 157
SSPBUF SSP Receive Buffer/Transmit Register xxxx xxxx 50, 195
SSPADD SSP Address Register in I2C Slave mode. SSP Baud Rate Reload Register in I2C Master mode. 0000 0000 50, 195
SSPSTAT SMP CKE D/A PSR/WUA BF 0000 0000 50, 197
SSPCON1 WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 50, 198
SSPCON2 GCEN ACKSTAT ACKDT ACKEN RCEN PEN RSEN SEN 0000 0000 50, 199
ADRESH A/D Result Register High Byte xxxx xxxx 50, 256
ADRESL A/D Result Register Low Byte xxxx xxxx 50, 256
ADCON0 —— CHS3 CHS2 CHS1 CHS0 GO/DONE ADON --00 0000 50, 247
ADCON1 —— VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 --00 0qqq 50, 248
ADCON2 ADFM — ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0 0-00 0000 50, 249
CCPR1H Capture/Compare/PWM Register 1 High Byte xxxx xxxx 51, 168
CCPR1L Capture/Compare/PWM Register 1 Low Byte xxxx xxxx 51, 168
CCP1CON  —— DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 --xx xxxx 51, 163
ECCPR1H(9) Enhanced Capture/Compare/PWM Register 1 High Byte xxxx xxxx 51, 167
ECCPR1L(9) Enhanced Capture/Compare/PWM Register 1 Low Byte xxxx xxxx 51, 167
ECCP1CON(9) EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0 0000 0000 51, 168
BAUDCON ABDOVF RCIDL — SCKP BRG16 — WUE ABDEN 01-0 0000 51, 230
ECCP1DEL(9) PRSEN PDC6(3) PDC5(3) PDC4(3) PDC3(3) PDC2(3) PDC1(3) PDC0(3) 0000 0000 51, 182
ECCP1AS(9) ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(3) PSSBD0(3) 0000 0000 51, 183
CVRCON(9) CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 0000 0000 51, 263
CMCON(9) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 51, 257
TMR3H Timer3 Register High Byte xxxx xxxx 51, 161
TMR3L Timer3 Register Low Byte xxxx xxxx 51, 161
T3CON RD16 T3ECCP1(9) T3CKPS1 T3CKPS0 T3CCP1(9) T3SYNC TMR3CS TMR3ON 0000 0000 51, 161
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680
DS39625C-page 78 Preliminary © 2007 Microchip Technology Inc.
SPBRGH EUSART Baud Rate Generator High Byte 0000 0000 51, 231
SPBRG EUSART Baud Rate Generator 0000 0000 51, 231
RCREG EUSART Receive Register 0000 0000 51, 238
TXREG EUSART Transmit Register 0000 0000 51, 236
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 0000 0010 51, 237
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 51, 237
EEADRH — — — — — — EEPROM Addr Register High ---- --00 51, 108
EEADR EEPROM Address Register 0000 0000 51, 105
EEDATA EEPROM Data Register 0000 0000 51, 105
EECON2 EEPROM Control Register 2 (not a physical register) 0000 0000 51, 105
EECON1 EEPGD CFGS — FREE WRERR WREN WR RD xx-0 x000 51, 105
IPR3
Mode 0
IRXIP WAKIP ERRIP TXB2IP TXB1IP TXB0IP RXB1IP RXB0IP 1111 1111 51, 126
IPR3
Mode 1, 2
IRXIP WAKIP ERRIP TXBnIP TXB1IP(8) TXB0IP(8) RXBnIP FIFOWMIP 1111 1111 51, 126
PIR3
Mode 0
IRXIF WAKIF ERRIF TXB2IF TXB1IF TXB0IF RXB1IF RXB0IF 0000 0000 51, 120
PIR3
Mode 1, 2
IRXIF WAKIF ERRIF TXBnIF TXB1IF(8) TXB0IF(8) RXBnIF FIFOWMIF 0000 0000 51, 120
PIE3
Mode 0
IRXIE WAKIE ERRIE TXB2IE TXB1IE TXB0IE RXB1IE RXB0IE 0000 0000 51, 123
PIE3
Mode 1, 2
IRXIE WAKIE ERRIE TXBnIE TXB1IE(8) TXB0IE(8) RXBnIE FIFOMWIE 0000 0000 51, 123
IPR2 OSCFIP CMIP(9) — EEIP BCLIP HLVDIP TMR3IP ECCP1IP(9) 11-1 1111 51, 125
PIR2 OSCFIF CMIF(9) — EEIF BCLIF HLVDIF TMR3IF ECCP1IF(9) 00-0 0000 51, 119
PIE2 OSCFIE CMIE(9) — EEIE BCLIE HLVDIE TMR3IE ECCP1IE(9) 00-0 0000 52, 122
IPR1 PSPIP(3) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 1111 1111 52, 124
PIR1 PSPIF(3) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 52, 118
PIE1 PSPIE(3) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 52, 121
OSCTUNE INTSRC PLLEN(4) — TUN4 TUN3 TUN2 TUN1 TUN0 0q-0 0000 27, 52
TRISE(3) IBF OBF IBOV PSPMODE — TRISE2 TRISE1 TRISE0 0000 -111 52, 141
TRISD(3) Data Direction Control Register for PORTD 1111 1111 52, 138
TRISC Data Direction Control Register for PORTC 1111 1111 52, 135
TRISB Data Direction Control Register for PORTB 1111 1111 52, 132
TRISA TRISA7(6) TRISA6(6) Data Direction Control Register for PORTA 1111 1111 52, 129
LATE(3) — — — — — LATE2 LATE1 LATE0 ---- -xxx 52, 141
LATD(3) Read PORTD Data Latch, Write PORTD Data Latch xxxx xxxx 52, 138
LATC Read PORTC Data Latch, Write PORTC Data Latch xxxx xxxx 52, 135
LATB Read PORTB Data Latch, Write PORTB Data Latch xxxx xxxx 52, 132
LATA LATA7(6) LATA6(6) Read PORTA Data Latch, Write PORTA Data Latch xxxx xxxx 52, 129
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 79
PIC18F2585/2680/4585/4680
PORTE(3) — — — —RE3
(5) RE2(3) RE1(3) RE0(3) ---- xxxx 52, 145
PORTD(3) Read PORTD pins, Write PORTD Data Latch  xxxx xxxx 52, 138
PORTC Read PORTC pins, Write PORTC Data Latch xxxx xxxx 52, 135
PORTB Read PORTB pins, Write PORTB Data Latch xxxx xxxx 52, 132
PORTA RA7(6) RA6(6) Read PORTA pins, Write PORTA Data Latch xx00 0000 52, 129
ECANCON MDSEL1 MDSEL0 FIFOWM EWIN4 EWIN3 EWIN2 EWIN1 EWIN0 0001 000 52, 280
TXERRCNT TEC7 TEC6 TEC5 TEC4 TEC3 TEC2 TEC1 TEC0 0000 0000 52, 285
RXERRCNT REC7 REC6 REC5 REC4 REC3 REC2 REC1 REC0 0000 0000 52, 293
COMSTAT
Mode 0
RXB0OVFL RXB1OVFL TXBO TXBP RXBP TXWARN RXWARN EWARN 0000 0000 52, 281
COMSTAT
Mode 1
— RXBnOVFL TXBO TXBP RXBP TXWARN RXWARN EWARN -000 0000 52, 281
COMSTAT
Mode 2
FIFOEMPTY RXBnOVFL TXBO TXBP RXBP TXWARN RXWARN EWARN 0000 0000 52, 281
CIOCON —— ENDRHI CANCAP — — — — --00 ---- 52, 314
BRGCON3 WAKDIS WAKFIL — — — SEG2PH2 SEG2PH1 SEG2PH0 00-- -000 52, 313
BRGCON2 SEG2PHTS SAM SEG1PH2 SEG1PH1 SEG1PH0 PRSEG2 PRSEG1 PRSEG0 0000 0000 52, 312
BRGCON1 SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0 0000 0000 52, 311
CANCON
Mode 0
REQOP2 REQOP1 REQOP0 ABAT WIN2(7) WIN1(7) WIN0(7) —(7) 1000 000- 53, 276
CANCON
Mode 1
REQOP2 REQOP1 REQOP0 ABAT —(7) —(7) —(7) —(7) 1000 ---- 53, 276
CANCON
Mode 2
REQOP2 REQOP1 REQOP0 ABAT FP3(7) FP2(7) FP1(7) FP0(7) 1000 0000 53, 276
CANSTAT
Mode 0
OPMODE2 OPMODE1 OPMODE0 —(7) ICODE3(7) ICODE2(7) ICODE1(7) —(7) 000- 0000 53, 277
CANSTAT
Modes 1, 2
OPMODE2 OPMODE1 OPMODE0 EICODE4(7) EICODE3(7) EICODE2(7) EICODE1(7) EICODE0(7) 0000 0000 53, 277
RXB0D7 RXB0D77 RXB0D76 RXB0D75 RXB0D74 RXB0D73 RXB0D72 RXB0D71 RXB0D70 xxxx xxxx 53, 292
RXB0D6 RXB0D67 RXB0D66 RXB0D65 RXB0D64 RXB0D63 RXB0D62 RXB0D61 RXB0D60 xxxx xxxx 53, 292
RXB0D5 RXB0D57 RXB0D56 RXB0D55 RXB0D54 RXB0D53 RXB0D52 RXB0D51 RXB0D50 xxxx xxxx 53, 292
RXB0D4 RXB0D47 RXB0D46 RXB0D45 RXB0D44 RXB0D43 RXB0D42 RXB0D41 RXB0D40 xxxx xxxx 53, 292
RXB0D3 RXB0D37 RXB0D36 RXB0D35 RXB0D34 RXB0D33 RXB0D32 RXB0D31 RXB0D30 xxxx xxxx 53, 292
RXB0D2 RXB0D27 RXB0D26 RXB0D25 RXB0D24 RXB0D23 RXB0D22 RXB0D21 RXB0D20 xxxx xxxx 53, 292
RXB0D1 RXB0D17 RXB0D16 RXB0D15 RXB0D14 RXB0D13 RXB0D12 RXB0D11 RXB0D10 xxxx xxxx 53, 292
RXB0D0 RXB0D07 RXB0D06 RXB0D05 RXB0D04 RXB0D03 RXB0D02 RXB0D01 RXB0D00 xxxx xxxx 53, 292
RXB0DLC — RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 53, 292
RXB0EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 53, 291
RXB0EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 53, 291
RXB0SIDL SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 53, 291
RXB0SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 53, 290
RXB0CON
Mode 0
RXFUL RXM1 RXM0(7) —(7)
RXRTRRO
(7)
RXBODBEN
(7)
JTOFF(7) FILHIT0(7) 000- 0000 53, 287
RXB0CON
Mode 1, 2
RXFUL RXM1 RTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 53, 287
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680
DS39625C-page 80 Preliminary © 2007 Microchip Technology Inc.
RXB1D7 RXB1D77 RXB1D76 RXB1D75 RXB1D74 RXB1D73 RXB1D72 RXB1D71 RXB1D70 xxxx xxxx 53, 292
RXB1D6 RXB1D67 RXB1D66 RXB1D65 RXB1D64 RXB1D63 RXB1D62 RXB1D61 RXB1D60 xxxx xxxx 53, 292
RXB1D5 RXB1D57 RXB1D56 RXB1D55 RXB1D54 RXB1D53 RXB1D52 RXB1D51 RXB1D50 xxxx xxxx 53, 292
RXB1D4 RXB1D47 RXB1D46 RXB1D45 RXB1D44 RXB1D43 RXB1D42 RXB1D41 RXB1D40 xxxx xxxx 53, 292
RXB1D3 RXB1D37 RXB1D36 RXB1D35 RXB1D34 RXB1D33 RXB1D32 RXB1D31 RXB1D30 xxxx xxxx 53, 292
RXB1D2 RXB1D27 RXB1D26 RXB1D25 RXB1D24 RXB1D23 RXB1D22 RXB1D21 RXB1D20 xxxx xxxx 53, 292
RXB1D1 RXB1D17 RXB1D16 RXB1D15 RXB1D14 RXB1D13 RXB1D12 RXB1D11 RXB1D10 xxxx xxxx 53, 292
RXB1D0 RXB1D07 RXB1D06 RXB1D05 RXB1D04 RXB1D03 RXB1D02 RXB1D01 RXB1D00 xxxx xxxx 53, 292
RXB1DLC — RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 53, 292
RXB1EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 53, 291
RXB1EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 53, 291
RXB1SIDL SID2 SID1 SID0 SRR EXID —EID17EID16xxxx xxxx 53, 291
RXB1SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 53, 290
RXB1CON
Mode 0
RXFUL RXM1 RXM0(7) —(7)
RXRTRRO
(7)
FILHIT2(7) FILHIT1(7) FILHIT0(7) 000- 0000 53, 287
RXB1CON
Mode 1, 2
RXFUL RXM1 RTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 53, 287
TXB0D7 TXB0D77 TXB0D76 TXB0D75 TXB0D74 TXB0D73 TXB0D72 TXB0D71 TXB0D70 xxxx xxxx 53, 284
TXB0D6 TXB0D67 TXB0D66 TXB0D65 TXB0D64 TXB0D63 TXB0D62 TXB0D61 TXB0D60 xxxx xxxx 53, 284
TXB0D5 TXB0D57 TXB0D56 TXB0D55 TXB0D54 TXB0D53 TXB0D52 TXB0D51 TXB0D50 xxxx xxxx 54, 284
TXB0D4 TXB0D47 TXB0D46 TXB0D45 TXB0D44 TXB0D43 TXB0D42 TXB0D41 TXB0D40 xxxx xxxx 54, 284
TXB0D3 TXB0D37 TXB0D36 TXB0D35 TXB0D34 TXB0D33 TXB0D32 TXB0D31 TXB0D30 xxxx xxxx 54, 284
TXB0D2 TXB0D27 TXB0D26 TXB0D25 TXB0D24 TXB0D23 TXB0D22 TXB0D21 TXB0D20 xxxx xxxx 54, 284
TXB0D1 TXB0D17 TXB0D16 TXB0D15 TXB0D14 TXB0D13 TXB0D12 TXB0D11 TXB0D10 xxxx xxxx 54, 284
TXB0D0 TXB0D07 TXB0D06 TXB0D05 TXB0D04 TXB0D03 TXB0D02 TXB0D01 TXB0D00 xxxx xxxx 54, 284
TXB0DLC —TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 54, 285
TXB0EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 54, 284
TXB0EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 54, 283
TXB0SIDL SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 54, 283
TXB0SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 54, 283
TXB0CON TXBIF TXABT TXLARB TXERR TXREQ — TXPRI1 TXPRI0 0000 0-00 54, 282
TXB1D7 TXB1D77 TXB1D76 TXB1D75 TXB1D74 TXB1D73 TXB1D72 TXB1D71 TXB1D70 xxxx xxxx 54, 284
TXB1D6 TXB1D67 TXB1D66 TXB1D65 TXB1D64 TXB1D63 TXB1D62 TXB1D61 TXB1D60 xxxx xxxx 54, 284
TXB1D5 TXB1D57 TXB1D56 TXB1D55 TXB1D54 TXB1D53 TXB1D52 TXB1D51 TXB1D50 xxxx xxxx 54, 284
TXB1D4 TXB1D47 TXB1D46 TXB1D45 TXB1D44 TXB1D43 TXB1D42 TXB1D41 TXB1D40 xxxx xxxx 54, 284
TXB1D3 TXB1D37 TXB1D36 TXB1D35 TXB1D34 TXB1D33 TXB1D32 TXB1D31 TXB1D30 xxxx xxxx 54, 284
TXB1D2 TXB1D27 TXB1D26 TXB1D25 TXB1D24 TXB1D23 TXB1D22 TXB1D21 TXB1D20 xxxx xxxx 54, 284
TXB1D1 TXB1D17 TXB1D16 TXB1D15 TXB1D14 TXB1D13 TXB1D12 TXB1D11 TXB1D10 xxxx xxxx 54, 284
TXB1D0 TXB1D07 TXB1D06 TXB1D05 TXB1D04 TXB1D03 TXB1D02 TXB1D01 TXB1D00 xxxx xxxx 54, 284
TXB1DLC —TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 54, 285
TXB1EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 54, 284
TXB1EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 54, 283
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 81
PIC18F2585/2680/4585/4680
TXB1SIDL SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 54, 283
TXB1SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 54, 283
TXB1CON TXBIF TXABT TXLARB TXERR TXREQ — TXPRI1 TXPRI0 0000 0-00 54, 282
TXB2D7 TXB2D77 TXB2D76 TXB2D75 TXB2D74 TXB2D73 TXB2D72 TXB2D71 TXB2D70 xxxx xxxx 54, 284
TXB2D6 TXB2D67 TXB2D66 TXB2D65 TXB2D64 TXB2D63 TXB2D62 TXB2D61 TXB2D60 xxxx xxxx 54, 284
TXB2D5 TXB2D57 TXB2D56 TXB2D55 TXB2D54 TXB2D53 TXB2D52 TXB2D51 TXB2D50 xxxx xxxx 54, 284
TXB2D4 TXB2D47 TXB2D46 TXB2D45 TXB2D44 TXB2D43 TXB2D42 TXB2D41 TXB2D40 xxxx xxxx 54, 284
TXB2D3 TXB2D37 TXB2D36 TXB2D35 TXB2D34 TXB2D33 TXB2D32 TXB2D31 TXB2D30 xxxx xxxx 54, 284
TXB2D2 TXB2D27 TXB2D26 TXB2D25 TXB2D24 TXB2D23 TXB2D22 TXB2D21 TXB2D20 xxxx xxxx 54, 284
TXB2D1 TXB2D17 TXB2D16 TXB2D15 TXB2D14 TXB2D13 TXB2D12 TXB2D11 TXB2D10 xxxx xxxx 55, 284
TXB2D0 TXB2D07 TXB2D06 TXB2D05 TXB2D04 TXB2D03 TXB2D02 TXB2D01 TXB2D00 xxxx xxxx 55, 284
TXB2DLC —TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 55, 285
TXB2EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 284
TXB2EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 283
TXB2SIDL SID2 SID1 SID0 — EXIDE —EID17EID16xxxx x-xx 55, 283
TXB2SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxx- x-xx 55, 283
TXB2CON TXBIF TXABT TXLARB TXERR TXREQ — TXPRI1 TXPRI0 0000 0-00 55, 282
RXM1EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 304
RXM1EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 304
RXM1SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 304
RXM1SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 304
RXM0EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 304
RXM0EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 304
RXM0SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 304
RXM0SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 303
RXF5EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 303
RXF5EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 303
RXF5SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 302
RXF5SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 302
RXF4EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 303
RXF4EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 303
RXF4SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 302
RXF4SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 302
RXF3EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 303
RXF3EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 303
RXF3SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 302
RXF3SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 302
RXF2EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 55, 303
RXF2EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 55, 303
RXF2SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 55, 302
RXF2SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 55, 302
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680
DS39625C-page 82 Preliminary © 2007 Microchip Technology Inc.
RXF1EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 56, 303
RXF1EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 56, 303
RXF1SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 56, 302
RXF1SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 56, 302
RXF0EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 56, 303
RXF0EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 56, 303
RXF0SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 56, 302
RXF0SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 56, 302
B5D7(8) B5D77 B5D76 B5D75 B5D74 B5D73 B5D72 B5D71 B5D70 xxxx xxxx 56, 299
B5D6(8) B5D67 B5D66 B5D65 B5D64 B5D63 B5D62 B5D61 B5D60 xxxx xxxx 56, 299
B5D5(8) B5D57 B5D56 B5D55 B5D54 B5D53 B5D52 B5D51 B5D50 xxxx xxxx 56, 299
B5D4(8) B5D47 B5D46 B5D45 B5D44 B5D43 B5D42 B5D41 B5D40 xxxx xxxx 56, 299
B5D3(8) B5D37 B5D36 B5D35 B5D34 B5D33 B5D32 B5D31 B5D30 xxxx xxxx 56, 299
B5D2(8) B5D27 B5D26 B5D25 B5D24 B5D23 B5D22 B5D21 B5D20 xxxx xxxx 56, 299
B5D1(8) B5D17 B5D16 B5D15 B5D14 B5D13 B5D12 B5D11 B5D10 xxxx xxxx 56, 299
B5D0(8) B5D07 B5D06 B5D05 B5D04 B5D03 B5D02 B5D01 B5D00 xxxx xxxx 56, 299
B5DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B5DLC(8) 
Transmit mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
B5EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 56, 299
B5EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 56, 298
B5SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B5SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B5SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx x-xx 56, 296
B5CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 56, 294
B5CON(8) 
Transmit mode
TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 56, 295
B4D7(8) B4D77 B4D76 B4D75 B4D74 B4D73 B4D72 B4D71 B4D70 xxxx xxxx 56, 299
B4D6(8) B4D67 B4D66 B4D65 B4D64 B4D63 B4D62 B4D61 B4D60 xxxx xxxx 56, 299
B4D5(8) B4D57 B4D56 B4D55 B4D54 B4D53 B4D52 B4D51 B4D50 xxxx xxxx 56, 299
B4D4(8) B4D47 B4D46 B4D45 B4D44 B4D43 B4D42 B4D41 B4D40 xxxx xxxx 56, 299
B4D3(8) B4D37 B4D36 B4D35 B4D34 B4D33 B4D32 B4D31 B4D30 xxxx xxxx 56, 299
B4D2(8) B4D27 B4D26 B4D25 B4D24 B4D23 B4D22 B4D21 B4D20 xxxx xxxx 56, 299
B4D1(8) B4D17 B4D16 B4D15 B4D14 B4D13 B4D12 B4D11 B4D10 xxxx xxxx 56, 299
B4D0(8) B4D07 B4D06 B4D05 B4D04 B4D03 B4D02 B4D01 B4D00 xxxx xxxx 56, 299
B4DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B4DLC(8) 
Transmit mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 83
PIC18F2585/2680/4585/4680
B4EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 56, 299
B4EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 57, 298
B4SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B4SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B4SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 57, 296
B4CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 57, 294
B4CON(8) 
Transmit mode
TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 57, 295
B3D7(8) B3D77 B3D76 B3D75 B3D74 B3D73 B3D72 B3D71 B3D70 xxxx xxxx 57, 299
B3D6(8) B3D67 B3D66 B3D65 B3D64 B3D63 B3D62 B3D61 B3D60 xxxx xxxx 57, 299
B3D5(8) B3D57 B3D56 B3D55 B3D54 B3D53 B3D52 B3D51 B3D50 xxxx xxxx 57, 299
B3D4(8) B3D47 B3D46 B3D45 B3D44 B3D43 B3D42 B3D41 B3D40 xxxx xxxx 57, 299
B3D3(8) B3D37 B3D36 B3D35 B3D34 B3D33 B3D32 B3D31 B3D30 xxxx xxxx 57, 299
B3D2(8) B3D27 B3D26 B3D25 B3D24 B3D23 B3D22 B3D21 B3D20 xxxx xxxx 57, 299
B3D1(8) B3D17 B3D16 B3D15 B3D14 B3D13 B3D12 B3D11 B3D10 xxxx xxxx 57, 299
B3D0(8) B3D07 B3D06 B3D05 B3D04 B3D03 B3D02 B3D01 B3D00 xxxx xxxx 57, 299
B3DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B3DLC(8) 
Transmit 
mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
B3EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 57, 299
B3EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 57, 298
B3SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B3SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B3SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 57, 296
B3CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 57, 294
B3CON(8) 
Transmit mode
TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 57, 295
B2D7(8) B2D77 B2D76 B2D75 B2D74 B2D73 B2D72 B2D71 B2D70 xxxx xxxx 57, 299
B2D6(8) B2D67 B2D66 B2D65 B2D64 B2D63 B2D62 B2D61 B2D60 xxxx xxxx 57, 299
B2D5(8) B2D57 B2D56 B2D55 B2D54 B2D53 B2D52 B2D51 B2D50 xxxx xxxx 57, 299
B2D4(8) B2D47 B2D46 B2D45 B2D44 B2D43 B2D42 B2D41 B2D40 xxxx xxxx 57, 299
B2D3(8) B2D37 B2D36 B2D35 B2D34 B2D33 B2D32 B2D31 B2D30 xxxx xxxx 57, 299
B2D2(8) B2D27 B2D26 B2D25 B2D24 B2D23 B2D22 B2D21 B2D20 xxxx xxxx 57, 299
B2D1(8) B2D17 B2D16 B2D15 B2D14 B2D13 B2D12 B2D11 B2D10 xxxx xxxx 57, 299
B2D0(8) B2D07 B2D06 B2D05 B2D04 B2D03 B2D02 B2D01 B2D00 xxxx xxxx 57, 299
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680
DS39625C-page 84 Preliminary © 2007 Microchip Technology Inc.
B2DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B2DLC(8) 
Transmit mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
B2EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 57, 299
B2EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 57, 298
B2SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B2SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B2SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 57, 296
B2CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 58, 294
B2CON(8) 
Transmit mode
TXBIF RXM1 TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 58, 295
B1D7(8) B1D77 B1D76 B1D75 B1D74 B1D73 B1D72 B1D71 B1D70 xxxx xxxx 58, 299
B1D6(8) B1D67 B1D66 B1D65 B1D64 B1D63 B1D62 B1D61 B1D60 xxxx xxxx 58, 299
B1D5(8) B1D57 B1D56 B1D55 B1D54 B1D53 B1D52 B1D51 B1D50 xxxx xxxx 58, 299
B1D4(8) B1D47 B1D46 B1D45 B1D44 B1D43 B1D42 B1D41 B1D40 xxxx xxxx 58, 299
B1D3(8) B1D37 B1D36 B1D35 B1D34 B1D33 B1D32 B1D31 B1D30 xxxx xxxx 58, 299
B1D2(8) B1D27 B1D26 B1D25 B1D24 B1D23 B1D22 B1D21 B1D20 xxxx xxxx 58, 299
B1D1(8) B1D17 B1D16 B1D15 B1D14 B1D13 B1D12 B1D11 B1D10 xxxx xxxx 58, 299
B1D0(8) B1D07 B1D06 B1D05 B1D04 B1D03 B1D02 B1D01 B1D00 xxxx xxxx 58, 299
B1DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B1DLC(8) 
Transmit mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
B1EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 58, 299
B1EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 58, 298
B1SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B1SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B1SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 58, 296
B1CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 58, 295
B1CON(8) 
Transmit mode
TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 58, 295
B0D7(8) B0D77 B0D76 B0D75 B0D74 B0D73 B0D72 B0D71 B0D70 xxxx xxxx 58, 299
B0D6(8) B0D67 B0D66 B0D65 B0D64 B0D63 B0D62 B0D61 B0D60 xxxx xxxx 58, 299
B0D5(8) B0D57 B0D56 B0D55 B0D54 B0D53 B0D52 B0D51 B0D50 xxxx xxxx 58, 299
B0D4(8) B0D47 B0D46 B0D45 B0D44 B0D43 B0D42 B0D41 B0D40 xxxx xxxx 58, 299
B0D3(8) B0D37 B0D36 B0D35 B0D34 B0D33 B0D32 B0D31 B0D30 xxxx xxxx 58, 299
B0D2(8) B0D27 B0D26 B0D25 B0D24 B0D23 B0D22 B0D21 B0D20 xxxx xxxx 58, 299
B0D1(8) B0D17 B0D16 B0D15 B0D14 B0D13 B0D12 B0D11 B0D10 xxxx xxxx 58, 299
B0D0(8) B0D07 B0D06 B0D05 B0D04 B0D03 B0D02 B0D01 B0D00 xxxx xxxx 58, 299
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 85
PIC18F2585/2680/4585/4680
B0DLC(8) 
Receive mode
— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0 -xxx xxxx 56, 300
B0DLC(8) 
Transmit mode
—TXRTR—— DLC3 DLC2 DLC1 DLC0 -x-- xxxx 56, 301
B0EIDL(8) EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 58, 299
B0EIDH(8) EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 58, 298
B0SIDL(8) 
Receive mode
SID2 SID1 SID0 SRR EXID —EID17EID16xxxx x-xx 56, 297
B0SIDL(8) 
Transmit mode
SID2 SID1 SID0 — EXIDE —EID17EID16xxx- x-xx 56, 297
B0SIDH(8) SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 58, 296
B0CON(8) 
Receive mode
RXFUL RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0 0000 0000 58, 295
B0CON(8) 
Transmit mode
TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0 0000 0000 58, 295
TXBIE — — — TXB2IE TXB1IE TXB0IE — — ---0 00-- 58, 318
BIE0 B5IE B4IE B3IE B2IE B1IE B0IE RXB1IE RXB0IE 0000 0000 58, 318
BSEL0 B5TXEN B4TXEN B3TXEN B2TXEN B1TXEN B0TXEN — — 0000 00-- 59, 301
MSEL3 FIL15_1 FIL15_0 FIL14_1 FIL14_0 FIL13_1 FIL13_0 FIL12_1 FIL12_0 0000 0000 59, 310
MSEL2 FIL11_1 FIL11_0 FIL10_1 FIL10_0 FIL9_1 FIL9_0 FIL8_1 FIL8_0 0000 0000 59, 309
MSEL1 FIL7_1 FIL7_0 FIL6_1 FIL6_0 FIL5_1 FIL5_0 FIL4_1 FIL4_0 0000 0101 59, 308
MSEL0 FIL3_1 FIL3_0 FIL2_1 FIL2_0 FIL1_1 FIL1_0 FIL0_1 FIL0_0 0101 0000 59, 307
RXFBCON7 F15BP_3 F15BP_2 F15BP_1 F15BP_0 F14BP_3 F14BP_2 F14BP_1 F14BP_0 0000 0000 59, 305
RXFBCON6 F13BP_3 F13BP_2 F13BP_1 F13BP_0 F12BP_3 F12BP_2 F12BP_1 F12BP_0 0000 0000 59, 305
RXFBCON5 F11BP_3 F11BP_2 F11BP_1 F11BP_0 F10BP_3 F10BP_2 F10BP_1 F10BP_0 0000 0000 59, 305
RXFBCON4 F9BP_3 F9BP_2 F9BP_1 F9BP_0 F8BP_3 F8BP_2 F8BP_1 F8BP_0 0000 0000 59, 305
RXFBCON3 F7BP_3 F7BP_2 F7BP_1 F7BP_0 F6BP_3 F6BP_2 F6BP_1 F6BP_0 0000 0000 59, 305
RXFBCON2 F5BP_3 F5BP_2 F5BP_1 F5BP_0 F4BP_3 F4BP_2 F4BP_1 F4BP_0 0001 0001 59, 305
RXFBCON1 F3BP_3 F3BP_2 F3BP_1 F3BP_0 F2BP_3 F2BP_2 F2BP_1 F2BP_0 0001 0001 59, 305
RXFBCON0 F1BP_3 F1BP_2 F1BP_1 F1BP_0 F0BP_3 F0BP_2 F0BP_1 F0BP_0 0000 0000 59, 305
SDFLC — — — FLC4 FLC3 FLC2 FLC1 FLC0 ---0 0000 59, 305
RXFCON1 RXF15EN RXF14EN RXF13EN RXF12EN RXF11EN RXF10EN RXF9EN RXF8EN 0000 0000 59, 306
RXFCON0 RXF7EN RXF6EN RXF5EN RXF4EN RXF3EN RXF2EN RXF1EN RXF0EN 0000 0000 59, 305
RXF15EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 59, 303
RXF15EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 59, 303
RXF15SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 59, 304
RXF15SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 59, 303
RXF14EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 59, 303
RXF14EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 59, 303
RXF14SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 59, 304
RXF14SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 59, 303
RXF13EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 59, 303
RXF13EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 59, 303
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680
DS39625C-page 86 Preliminary © 2007 Microchip Technology Inc.
RXF13SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 59, 304
RXF13SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 59, 303
RXF12EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 59, 303
RXF12EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 59, 303
RXF12SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 59, 304
RXF12SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF11EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF11EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF11SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF11SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF10EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF10EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF10SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF10SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF9EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF9EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF9SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF9SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF8EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF8EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF8SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF8SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF7EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF7EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF7SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF7SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
RXF6EIDL EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0 xxxx xxxx 60, 303
RXF6EIDH EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8 xxxx xxxx 60, 303
RXF6SIDL SID2 SID1 SID0 — EXIDEN —EID17EID16xxx- x-xx 60, 304
RXF6SIDH SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3 xxxx xxxx 60, 303
TABLE 5-2: REGISTER FILE SUMMARY (PIC18F2585/2680/4585/4680) (CONTINUED)
File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on 
POR, BOR
Details 
on page:
Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition
Note 1: Bit 21 of the PC is only available in Test mode and Serial Programming modes.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’. See Section 4.4 “Brown-out Reset 
(BOR)”.
3: These registers and/or bits are not implemented on PIC18F2X8X devices and are read as ‘0’. Reset values are shown for PIC18F4X8X 
devices; individual unimplemented bits should be interpreted as ‘—’.
4: The PLLEN bit is only available in specific oscillator configuration; otherwise, it is disabled and reads as ‘0’. See Section 2.6.4 “PLL in 
INTOSC Modes”.
5: The RE3 bit is only available when Master Clear Reset is disabled (CONFIG3H<7> = 0); otherwise, RE3 reads as ‘0’. This bit is read-only.
6: RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. 
When disabled, these bits read as ‘0’.
7: CAN bits have multiple functions depending on the selected mode of the CAN module.
8: This register reads all ‘0’s until the ECAN™ technology is set up in Mode 1 or Mode 2.
9: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680

5.3.5 STATUS REGISTER

The STATUS register, shown in Register 5-2, contains

the arithmetic status of the ALU. As with any other SFR,

it can be the operand for any instruction.

If the STATUS register is the destination for an instruc-

tion that affects the Z, DC, C, OV or N bits, the results

of the instruction are not written; instead, the status is

updated according to the instruction performed. There-

fore, the result of an instruction with the STATUS

intended. As an example, CLRF STATUS will set the Z

bit and leave the remaining Status bits unchanged

(‘000u u1uu’).

It is recommended that only BCF, BSF, SWAPF, MOVFF

and MOVWF instructions are used to alter the STATUS

C, DC, OV or N bits in the STATUS register.

For other instructions that do not affect Status bits, see

the instruction set summaries in Table 25-2 and

Table 25-3.

Note: The C and DC bits operate as the borrow

and digit borrow bits respectively in

subtraction.

U-0 U-0 U-0 R/W-x R/W-x R/W-x R/W-x R/W-x

— — —NOVZDCC

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4 N: Negative bit

This bit is used for signed arithmetic (2’s complement). It indicates whether the result was

negative (ALU MSB = 1).

1 = Result was negative

0 = Result was positive

bit 3 OV: Overflow bit

This bit is used for signed arithmetic (2’s complement). It indicates an overflow of the 7-bit

magnitude which causes the sign bit (bit 7) to change state.

1 = Overflow occurred for signed arithmetic (in this arithmetic operation)

0 = No overflow occurred

bit 2 Z: Zero bit

1 = The result of an arithmetic or logic operation is zero

0 = The result of an arithmetic or logic operation is not zero

bit 1 DC: Digit carry/borrow bit

For ADDWF, ADDLW, SUBLW and SUBWF instructions:

1 = A carry-out from the 4th low-order bit of the result occurred

0 = No carry-out from the 4th low-order bit of the result

Note: For borrow, the polarity is reversed. A subtraction is executed by adding the two’s

complement of the second operand. For rotate (RRF, RLF) instructions, this bit is

loaded with either the bit 4 or bit 3 of the source register.

bit 0 C: Carry/borrow bit

For ADDWF, ADDLW, SUBLW and SUBWF instructions:

1 = A carry-out from the Most Significant bit of the result occurred

0 = No carry-out from the Most Significant bit of the result occurred

Note: For borrow, the polarity is reversed. A subtraction is executed by adding the two’s

complement of the second operand. For rotate (RRF, RLF) instructions, this bit is

loaded with either the high or low-order bit of the source register.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680
DS39625C-page 88 Preliminary © 2007 Microchip Technology Inc.
5.4 Data Addressing Modes
While the program memory can be addressed in only
one way – through the program counter – information
in the data memory space can be addressed in several
ways. For most instructions, the addressing mode is
fixed. Other instructions may use up to three modes,
depending on which operands are used and whether or
not the extended instruction set is enabled.
The addressing modes are:
• Inherent
• Literal
•Direct
•Indirect
An additional addressing mode, Indexed Literal Offset,
is available when the extended instruction set is
enabled (XINST Configuration bit = 1). Its operation is
discussed in greater detail in Section 5.6.1 “Indexed
Addressing with Literal Offset”. 
5.4.1 INHERENT AND LITERAL 
ADDRESSING
Many PIC18 control instructions do not need any
argument at all; they either perform an operation that
globally affects the device or they operate implicitly on
one register. This addressing mode is known as
Inherent Addressing. Examples include SLEEP, RESET
and DAW.
Other instructions work in a similar way but require an
additional explicit argument in the opcode. This is
known as Literal Addressing mode because they
require some literal value as an argument. Examples
include ADDLW and MOVLW which, respectively, add or
move a literal value to the W register. Other examples
include  CALL and GOTO, which include a 20-bit
program memory address.
5.4.2 DIRECT ADDRESSING
Direct addressing specifies all or part of the source
and/or destination address of the operation within the
opcode itself. The options are specified by the
arguments accompanying the instruction.
In the core PIC18 instruction set, bit-oriented and
byte-oriented instructions use some version of direct
addressing by default. All of these instructions include
some 8-bit literal address as their Least Significant
Byte. This address specifies either a register address in
one of the banks of data RAM (Section 5.3.3 “General
Purpose Register File”) or a location in the Access
Bank (Section 5.3.2 “Access Bank”) as the data
source for the instruction. 
The Access RAM bit ‘a’ determines how the address is
interpreted. When ‘a’ is ‘1’, the contents of the BSR
(Section 5.3.1 “Bank Select Register (BSR)”) are
used with the address to determine the complete 12-bit
address of the register. When ‘a’ is ‘0’, the address is
interpreted as being a register in the Access Bank.
Addressing that uses the Access RAM is sometimes
also known as Direct Forced Addressing mode.
A few instructions, such as MOVFF, include the entire
12-bit address (either source or destination) in their
opcodes. In those cases, the BSR is ignored entirely.
The destination of the operation’s results is determined
by the destination bit ‘d’. When ‘d’ is ‘1’, the results are
stored back in the source register, overwriting its origi-
nal contents. When ‘d’ is ‘0’, the results are stored in
the W register. Instructions without the ‘d’ argument
have a destination that is implicit in the instruction; their
destination is either the target register being operated
on or the W register.
5.4.3 INDIRECT ADDRESSING
Indirect addressing allows the user to access a location
in data memory without giving a fixed address in the
instruction. This is done by using File Select Registers
(FSRs) as pointers to the locations to be read or written
to. Since the FSRs are themselves located in RAM as
Special File Registers, they can also be directly manip-
ulated under program control. This makes FSRs very
useful in implementing data structures, such as tables
and arrays in data memory. 
The registers for indirect addressing are also imple-
mented with Indirect File Operands (INDFs) that permit
automatic manipulation of the pointer value with
auto-incrementing, auto-decrementing or offsetting
with another value. This allows for efficient code, using
loops, such as the example of clearing an entire RAM
bank in Example 5-5.
EXAMPLE 5-5: HOW TO CLEAR RAM 
(BANK 1) USING 
INDIRECT ADDRESSING   
Note: The execution of some instructions in the
core PIC18 instruction set are changed
when the PIC18 extended instruction
set is enabled. See Section 5.6 “Data
Memory and the Extended Instruction
Set” for more information.
LFSR FSR0, 100h ;   
NEXT  CLRF POSTINC0 ; Clear INDF 
; register then 
; inc pointer 
BTFSS FSR0H, 1 ; All done with
; Bank1? 
BRA NEXT ; NO, clear next 
CONTINUE ; YES, continue 

PIC18F2585/2680/4585/4680

5.4.3.1 FSR Registers and the

INDF Operand

At the core of indirect addressing are three sets of

registers: FSR0, FSR1 and FSR2. Each represents a

pair of 8-bit registers, FSRnH and FSRnL. The four

upper bits of the FSRnH register are not used, so each

FSR pair holds a 12-bit value. This represents a value

that can address the entire range of the data memory

in a linear fashion. The FSR register pairs, then, serve

as pointers to data memory locations.

Indirect addressing is accomplished with a set of

Indirect File Operands, INDF0 through INDF2. These

can be thought of as “virtual” registers: they are

mapped in the SFR space, but are not physically

implemented. Reading or writing to a particular INDF

the data at the address indicated by FSR1H:FSR1L.

Instructions that use the INDF registers as operands

actually use the contents of their corresponding FSR as

a pointer to the instruction’s target. The INDF operand

is just a convenient way of using the pointer.

Because indirect addressing uses a full 12-bit address,

data RAM banking is not necessary. Thus, the current

contents of the BSR and the Access RAM bit have no

effect on determining the target address.

FIGURE 5-7: INDIRECT ADDRESSING

FSR1H:FSR1L

Data Memory

000h

100h

200h

300h

F00h

E00h

FFFh

Bank 0

Bank 1

Bank 2

Bank 14

Bank 15

Bank 3

through

Bank 13

ADDWF, INDF1, 1

Using an instruction with one of the

indirect addressing registers as the

operand....

...uses the 12-bit address stored in

the FSR pair associated with that

...to determine the data memory

location to be used in that operation.

In this case, the FSR1 pair contains

ECCh. This means the contents of

location ECCh will be added to that

of the W register and stored back in

ECCh.

xxxx1110 11001100

Bank 14

PIC18F2585/2680/4585/4680

5.4.3.2 FSR Registers and POSTINC,

POSTDEC, PREINC and PLUSW

In addition to the INDF operand, each FSR register pair

also has four additional indirect operands. Like INDF,

these are “virtual” registers that cannot be indirectly

read or written to. Accessing these registers actually

accesses the associated FSR register pair, but also

performs a specific action on its stored value. They are:

• POSTDEC: accesses the FSR value, then

automatically decrements it by 1 afterwards

• POSTINC: accesses the FSR value, then

automatically increments it by 1 afterwards

• PREINC: increments the FSR value by 1, then

uses it in the operation

• PLUSW: adds the signed value of the W register

(range of -127 to 128) to that of the FSR and uses

the new value in the operation.

In this context, accessing an INDF register uses the

value in the FSR registers without changing them.

Similarly, accessing a PLUSW register gives the FSR

value offset by that in the W register; neither value is

actually changed in the operation. Accessing the other

virtual registers changes the value of the FSR

registers.

Operations on the FSRs with POSTDEC, POSTINC

and PREINC affect the entire register pair; that is,

rollovers of the FSRnL register from FFh to 00h carry

over to the FSRnH register. On the other hand, results

of these operations do not change the value of any

flags in the STATUS register (e.g., Z, N, OV, etc.).

The PLUSW register can be used to implement a form

of indexed addressing in the data memory space. By

manipulating the value in the W register, users can

reach addresses that are fixed offsets from pointer

addresses. In some applications, this can be used to

implement some powerful program control structure,

such as software stacks, inside of data memory.

5.4.3.3 Operations by FSRs on FSRs

Indirect addressing operations that target other FSRs

or virtual registers represent special cases. For exam-

ple, using an FSR to point to one of the virtual registers

will not result in successful operations. As a specific

case, assume that FSR0H:FSR0L contains FE7h, the

address of INDF1. Attempts to read the value of the

INDF1 using INDF0 as an operand will return 00h.

Attempts to write to INDF1 using INDF0 as the operand

will result in a NOP.

On the other hand, using the virtual registers to write to

an FSR pair may not occur as planned. In these cases,

the value will be written to the FSR pair but without any

incrementing or decrementing. Thus, writing to INDF2

or POSTDEC2 will write the same value to the

FSR2H:FSR2L.

Since the FSRs are physical registers mapped in the

SFR space, they can be manipulated through all direct

operations. Users should proceed cautiously when

working on these registers, particularly if their code

uses indirect addressing.

Similarly, operations by indirect addressing are gener-

ally permitted on all other SFRs. Users should exercise

the appropriate caution that they do not inadvertently

change settings that might affect the operation of the

device.

PIC18F2585/2680/4585/4680

5.5 Program Memory and the

Extended Instruction Set

The operation of program memory is unaffected by the

use of the extended instruction set.

Enabling the extended instruction set adds eight

additional two-word commands to the existing

PIC18 instruction set: ADDFSR, ADDULNK, CALLW,

MOVSF, MOVSS, PUSHL, SUBFSR and SUBULNK. These

instructions are executed as described in

Section 5.2.4 “Two-Word Instructions”.

5.6 Data Memory and the Extended

Instruction Set

Enabling the PIC18 extended instruction set (XINST

Configuration bit = 1) significantly changes certain

aspects of data memory and its addressing. Specifi-

cally, the use of the Access Bank for many of the core

PIC18 instructions is different; this is due to the intro-

duction of a new addressing mode for the data memory

space. This mode also alters the behavior of indirect

addressing using FSR2 and its associated operands.

What does not change is just as important. The size of

the data memory space is unchanged, as well as its

linear addressing. The SFR map remains the same.

Core PIC18 instructions can still operate in both Direct

and Indirect Addressing mode; inherent and literal

instructions do not change at all. Indirect addressing

with FSR0 and FSR1 also remains unchanged.

5.6.1 INDEXED ADDRESSING WITH

LITERAL OFFSET

Enabling the PIC18 extended instruction set changes

the behavior of indirect addressing using the FSR2

proper conditions, instructions that use the Access

Bank – that is, most bit-oriented and byte-oriented –

instructions – can invoke a form of indexed addressing

using an offset specified in the instruction. This special

addressing mode is known as Indexed Addressing with

Literal Offset or Indexed Literal Offset mode.

When using the extended instruction set, this

addressing mode requires the following:

• The use of the Access Bank is forced (‘a’ = 0);

and

• The file address argument is less than or equal to

5Fh.

Under these conditions, the file address of the instruc-

tion is not interpreted as the lower byte of an address

(used with the BSR in direct addressing), or as an 8-bit

address in the Access Bank. Instead, the value is

interpreted as an offset value to an address pointer,

specified by FSR2. The offset and the contents of

FSR2 are added to obtain the target address of the

operation.

5.6.2 INSTRUCTIONS AFFECTED BY

INDEXED LITERAL OFFSET MODE

Any of the core PIC18 instructions that can use direct

addressing are potentially affected by the Indexed

Literal Offset Addressing mode. This includes all

byte-oriented and bit-oriented instructions, or almost

one-half of the standard PIC18 instruction set. Instruc-

tions that only use Inherent or Literal Addressing

modes are unaffected.

Additionally, byte-oriented and bit-oriented instructions

are not affected if they use the Access Bank (Access

RAM bit is ‘1’), or include a file address of 60h or above.

Instructions meeting these criteria will continue to

execute as before. A comparison of the different possi-

ble addressing modes when the extended instruction

set is enabled in shown in Figure 5-8.

Those who desire to use byte-oriented or bit-oriented

instructions in the Indexed Literal Offset mode should

note the changes to assembler syntax for this mode.

This is described in more detail in Section 25.2.1

“Extended Instruction Syntax”.

PIC18F2585/2680/4585/4680

FIGURE 5-8: COMPARING ADDRESSING OPTIONS FOR BIT-ORIENTED AND

BYTE-ORIENTED INSTRUCTIONS (EXTENDED INSTRUCTION SET ENABLED)

EXAMPLE INSTRUCTION: ADDWF, f, d, a (Opcode: 0010 01da ffff ffff)

When a = 0 and f ≥ 60h:

The instruction executes in

Direct Forced mode. ‘f’ is

interpreted as a location in the

Access RAM between 060h

and 0FFh. This is the same as

the SFRs, or locations F60h to

0FFh (Bank 15) of data

memory.

Locations below 60h are not

available in this addressing

mode.

When a = 0 and f ≤ 5Fh:

The instruction executes in

Indexed Literal Offset mode. ‘f’

is interpreted as an offset to the

address value in FSR2. The

two are added together to

obtain the address of the target

address can be anywhere in

the data memory space.

Note that in this mode, the

correct syntax is now:

ADDWF [k], d

where ‘k’ is the same as ‘f’.

When a = 1 (all values of f):

The instruction executes in

Direct mode (also known as

Direct Long mode). ‘f’ is

interpreted as a location in

one of the 16 banks of the data

memory space. The bank is

designated by the Bank Select

can be in any implemented

bank in the data memory

space.

000h

060h

100h

F00h

F60h

FFFh

Valid range

00h

60h

FFh

Data Memory

Access RAM

Bank 0

Bank 1

through

Bank 14

Bank 15

SFRs

000h

080h

100h

F00h

F60h

FFFh

Data Memory

Bank 0

Bank 1

through

Bank 14

Bank 15

SFRs

FSR2H FSR2L

ffffffff001001da

000h

080h

100h

F00h

F60h

FFFh

Data Memory

Bank 0

Bank 1

through

Bank 14

Bank 15

SFRs

for ‘f’

BSR

00000000

080h

PIC18F2585/2680/4585/4680

5.6.3 MAPPING THE ACCESS BANK IN

INDEXED LITERAL OFFSET MODE

The use of Indexed Literal Offset Addressing mode

effectively changes how the lower half of Access RAM

(00h to 7Fh) is mapped. Rather than containing just the

contents of the bottom half of Bank 0, this mode maps

the contents from Bank 0 and a user defined “window”

that can be located anywhere in the data memory

space. The value of FSR2 establishes the lower bound-

ary of the addresses mapped into the window, while the

upper boundary is defined by FSR2 plus 95 (5Fh).

Addresses in the Access RAM above 5Fh are mapped

as previously described (see Section 5.3.2 “Access

Bank”). An example of Access Bank remapping in this

addressing mode is shown in Figure 5-9.

Remapping of the Access Bank applies

only

to opera-

tions using the Indexed Literal Offset mode. Operations

that use the BSR (Access RAM bit is ‘1’) will continue

to use direct addressing as before. Any indirect or

indexed operation that explicitly uses any of the indirect

file operands (including FSR2) will continue to operate

as standard indirect addressing. Any instruction that

uses the Access Bank, but includes a register address

of greater than 05Fh, will use direct addressing and the

normal Access Bank map.

5.6.4 BSR IN INDEXED LITERAL

OFFSET MODE

Although the Access Bank is remapped when the

extended instruction set is enabled, the operation of the

BSR remains unchanged. Direct addressing using the

BSR to select the data memory bank operates in the

same manner as previously described.

FIGURE 5-9: REMAPPING THE ACCESS BANK WITH INDEXED LITERAL

OFFSET ADDRESSING

Data Memory

000h

100h

200h

F60h

F00h

FFFh

Bank 1

Bank 15

Bank 2

through

Bank 14

SFRs

ADDWF f, d, a

FSR2H:FSR2L = 120h

Locations in the region

from the FSR2 pointer

(120h) to the pointer plus

05Fh (17Fh) are mapped

to the bottom of the

Access RAM (000h-05Fh).

Special File Registers at

F60h through FFFh are

mapped to 60h through

FFh, as usual.

Bank 0 addresses below

5Fh are not available in

this mode. They can still

be addressed by using the

BSR.

Access Bank

00h

60h

FFh

Bank 0

SFRs

Bank 1 “Window”

Window

Example Situation:

120h

17Fh

5Fh

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

6.0 FLASH PROGRAM MEMORY

The Flash program memory is readable, writable and

erasable during normal operation over the entire VDD

range.

A read from program memory is executed on one byte

at a time. A write to program memory is executed on

blocks of 64 bytes at a time. Program memory is

erased in blocks of 64 bytes at a time. A bulk erase

operation may not be issued from user code.

Writing or erasing program memory will cease

instruction fetches until the operation is complete. The

program memory cannot be accessed during the write

or erase, therefore, code cannot execute. An internal

programming timer terminates program memory writes

and erases.

A value written to program memory does not need to be

a valid instruction. Executing a program memory

location that forms an invalid instruction results in a

NOP.

6.1 Table Reads and Table Writes

In order to read and write program memory, there are

two operations that allow the processor to move bytes

between the program memory space and the data RAM:

• Table Read (TBLRD)

• Table Write (TBLWT)

The program memory space is 16 bits wide, while the

data RAM space is 8 bits wide. Table reads and table

writes move data between these two memory spaces

through an 8-bit register (TABLAT).

Table read operations retrieve data from program

memory and place it into the data RAM space.

Figure 6-1 shows the operation of a table read with

program memory and data RAM.

Table write operations store data from the data memory

space into holding registers in program memory. The

procedure to write the contents of the holding registers

into program memory is detailed in Section 6.5 “Writing

to Flash Program Memory”. Figure 6-2 shows the

operation of a table write with program memory and data

RAM.

Table operations work with byte entities. A table block

containing data, rather than program instructions, is not

required to be word aligned. Therefore, a table block can

start and end at any byte address. If a table write is being

used to write executable code into program memory,

program instructions will need to be word aligned.

FIGURE 6-1: TABLE READ OPERATION

Table Pointer(1)

Table Latch (8-bit)

Program Memory

TBLPTRH TBLPTRL

TABLAT

TBLPTRU

Instruction: TBLRD*

Note 1: Table Pointer register points to a byte in program memory.

Program Memory

(TBLPTR)

PIC18F2585/2680/4585/4680

FIGURE 6-2: TABLE WRITE OPERATION

6.2 Control Registers

Several control registers are used in conjunction with

the TBLRD and TBLWT instructions. These include the:

• EECON1 register

• EECON2 register

• TABLAT register

• TBLPTR registers

6.2.1 EECON1 AND EECON2 REGISTERS

The EECON1 register (Register 6-1) is the control

not a physical register; it is used exclusively in the

memory write and erase sequences. Reading

EECON2 will read all ‘0’s.

The EEPGD control bit determines if the access will be

a program or data EEPROM memory access. When

clear, any subsequent operations will operate on the

data EEPROM memory. When set, any subsequent

operations will operate on the program memory.

The CFGS control bit determines if the access will be

to the Configuration/Calibration registers or to program

memory/data EEPROM memory. When set,

subsequent operations will operate on Configuration

registers regardless of EEPGD (see Section 24.0

“Special Features of the CPU”). When clear, memory

selection access is determined by EEPGD.

The FREE bit, when set, will allow a program memory

erase operation. When FREE is set, the erase opera-

tion is initiated on the next WR command. When FREE

is clear, only writes are enabled.

The WREN bit, when set, will allow a write operation.

On power-up, the WREN bit is clear. The WRERR bit is

set in hardware when the WREN bit is set and cleared

when the internal programming timer expires and the

write operation is complete.

The WR control bit initiates write operations. The bit

cannot be cleared, only set, in software; it is cleared in

hardware at the completion of the write operation.

Table Pointer(1) Table Latch (8-bit)

TBLPTRH TBLPTRL TABLAT

Program Memory

(TBLPTR)

TBLPTRU

Instruction: TBLWT*

Note 1: Table Pointer actually points to one of 64 holding registers, the address of which is determined by

TBLPTRL<5:0>. The process for physically writing data to the program memory array is discussed in

Section 6.5 “Writing to Flash Program Memory”.

Holding Registers

Program Memory

Note: During normal operation, the WRERR is

read as ‘1’. This can indicate that a write

operation was prematurely terminated by

a Reset, or a write operation was

attempted improperly.

Note: The EEIF Interrupt flag bit (PIR2<4>) is set

when the write is complete. It must be

cleared in software.

PIC18F2585/2680/4585/4680

R/W-x R/W-x U-0 R/W-0 R/W-x R/W-0 R/S-0 R/S-0

EEPGD CFGS — FREE WRERR WREN WR RD

bit 7 bit 0

bit 7 EEPGD: Flash Program or Data EEPROM Memory Select bit

1 = Access Flash program memory

0 = Access data EEPROM memory

bit 6 CFGS: Flash Program/Data EEPROM or Configuration Select bit

1 = Access Configuration registers

0 = Access Flash program or data EEPROM memory

bit 5 Unimplemented: Read as ‘0’

bit 4 FREE: Flash Row Erase Enable bit

1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared

by completion of erase operation)

0 = Perform write only

bit 3 WRERR: Flash Program/Data EEPROM Error Flag bit

1 = A write operation is prematurely terminated (any Reset during self-timed programming in

normal operation or an improper write attempt)

0 = The write operation completed

Note: When a WRERR occurs, the EEPGD and CFGS bits are not cleared.

This allows tracing of the error condition.

bit 2 WREN: Flash Program/Data EEPROM Write Enable bit

1 = Allows write cycles to Flash program/data EEPROM

0 = Inhibits write cycles to Flash program/data EEPROM

bit 1 WR: Write Control bit

1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle

(The operation is self-timed and the bit is cleared by hardware once write is complete.

The WR bit can only be set (not cleared) in software.)

0 = Write cycle to the EEPROM is complete

bit 0 RD: Read Control bit

1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can

only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.)

0 = Does not initiate an EEPROM read

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

6.2.2 TABLAT – TABLE LATCH REGISTER

The Table Latch (TABLAT) is an 8-bit register mapped

into the SFR space. The Table Latch register is used to

hold 8-bit data during data transfers between program

memory and data RAM.

6.2.3 TBLPTR – TABLE POINTER

The Table Pointer (TBLPTR) register addresses a byte

within the program memory. The TBLPTR is comprised

of three SFR registers: Table Pointer Upper Byte, Table

Pointer High Byte and Table Pointer Low Byte

(TBLPTRU:TBLPTRH:TBLPTRL). These three regis-

ters join to form a 22-bit wide pointer. The low-order

21 bits allow the device to address up to 2 Mbytes of

program memory space. The 22nd bit allows access to

the device ID, the user ID and the Configuration bits.

The Table Pointer, TBLPTR, is used by the TBLRD and

TBLWT instructions. These instructions can update the

TBLPTR in one of four ways based on the table opera-

tion. These operations are shown in Table 6-1. These

operations on the TBLPTR only affect the low-order

21 bits.

6.2.4 TABLE POINTER BOUNDARIES

TBLPTR is used in reads, writes and erases of the

Flash program memory.

When a TBLRD is executed, all 22 bits of the TBLPTR

determine which byte is read from program memory

into TABLAT.

When a TBLWT is executed, the six LSbs of the Table

Pointer register (TBLPTR<5:0>) determine which of the

64 program memory holding registers is written to.

When the timed write to program memory begins (via

the WR bit), the 16 MSbs of the TBLPTR

(TBLPTR<21:6>) determine which program memory

block of 64 bytes is written to. For more detail, see

Section 6.5 “Writing to Flash Program Memory”.

When an erase of program memory is executed, the

16 MSbs of the Table Pointer register (TBLPTR<21:6>)

point to the 64-byte block that will be erased. The Least

Significant bits (TBLPTR<5:0>) are ignored.

Figure 6-3 describes the relevant boundaries of

TBLPTR based on Flash program memory operations.

TABLE 6-1: TABLE POINTER OPERATIONS WITH TBLRD AND TBLWT INSTRUCTIONS

FIGURE 6-3: TABLE POINTER BOUNDARIES BASED ON OPERATION

Example Operation on Table Pointer

TBLRD*

TBLWT* TBLPTR is not modified

TBLRD*+

TBLWT*+ TBLPTR is incremented after the read/write

TBLRD*-

TBLWT*- TBLPTR is decremented after the read/write

TBLRD+*

TBLWT+* TBLPTR is incremented before the read/write

21 16 15 87 0

TABLE ERASE/WRITE TABLE WRITE

TABLE READ – TBLPTR<21:0>

TBLPTRL

TBLPTRH

TBLPTRU

TBLPTR<5:0>TBLPTR<21:6>

PIC18F2585/2680/4585/4680

6.3 Reading the Flash Program

Memory

The TBLRD instruction is used to retrieve data from

program memory and places it into data RAM. Table

reads from program memory are performed one byte at

a time.

TBLPTR points to a byte address in program space.

Executing TBLRD places the byte pointed to into

TABLAT. In addition, TBLPTR can be modified

automatically for the next table read operation.

The internal program memory is typically organized by

words. The Least Significant bit of the address selects

between the high and low bytes of the word. Figure 6-4

shows the interface between the internal program

memory and the TABLAT.

FIGURE 6-4: READS FROM FLASH PROGRAM MEMORY

EXAMPLE 6-1: READING A FLASH PROGRAM MEMORY WORD

(Even Byte Address)

Program Memory

(Odd Byte Address)

TBLRD TABLAT

TBLPTR = xxxxx1

FETCH

Instruction Register

(IR) Read Register

TBLPTR = xxxxx0

MOVLW CODE_ADDR_UPPER ; Load TBLPTR with the base

MOVWF TBLPTRU ; address of the word

MOVLW CODE_ADDR_HIGH

MOVWF TBLPTRH

MOVLW CODE_ADDR_LOW

MOVWF TBLPTRL

READ_WORD

TBLRD*+ ; read into TABLAT and increment

MOVF TABLAT, W ; get data

MOVWF WORD_EVEN

TBLRD*+ ; read into TABLAT and increment

MOVF TABLAT, W ; get data

MOVF WORD_ODD

PIC18F2585/2680/4585/4680

6.4 Erasing Flash Program Memory

The minimum erase block is 32 words or 64 bytes. Only

through the use of an external programmer, or through

ICSP control, can larger blocks of program memory be

bulk erased. Word erase in the Flash array is not

supported.

When initiating an erase sequence from the micro-

controller itself, a block of 64 bytes of program memory

is erased. The Most Significant 16 bits of the

TBLPTR<21:6> point to the block being erased.

TBLPTR<5:0> are ignored.

The EECON1 register commands the erase operation.

The EEPGD bit must be set to point to the Flash

program memory. The WREN bit must be set to enable

write operations. The FREE bit is set to select an erase

operation.

For protection, the write initiate sequence for EECON2

must be used.

A long write is necessary for erasing the internal Flash.

Instruction execution is halted while in a long write

cycle. The long write will be terminated by the internal

programming timer.

6.4.1 FLASH PROGRAM MEMORY

ERASE SEQUENCE

The sequence of events for erasing a block of internal

program memory location is:

1. Load Table Pointer register with address of row

being erased.

2. Set the EECON1 register for the erase operation:

• set EEPGD bit to point to program memory;

• clear the CFGS bit to access program memory;

• set WREN bit to enable writes;

• set FREE bit to enable the erase.

3. Disable interrupts.

4. Write 55h to EECON2.

5. Write 0AAh to EECON2.

6. Set the WR bit. This will begin the row erase

cycle.

7. The CPU will stall for duration of the erase

(about 2 ms using internal timer).

8. Re-enable interrupts.

EXAMPLE 6-2: ERASING A FLASH PROGRAM MEMORY ROW

MOVLW CODE_ADDR_UPPER ; load TBLPTR with the base

MOVWF TBLPTRU ; address of the memory block

MOVLW CODE_ADDR_HIGH

MOVWF TBLPTRH

MOVLW CODE_ADDR_LOW

MOVWF TBLPTRL

ERASE_ROW

BSF EECON1, EEPGD ; point to Flash program memory

BCF EECON1, CFGS ; access Flash program memory

BSF EECON1, WREN ; enable write to memory

BSF EECON1, FREE ; enable Row Erase operation

BCF INTCON, GIE ; disable interrupts

Required MOVLW 55h

Sequence MOVWF EECON2 ; write 55h

MOVLW 0AAh

MOVWF EECON2 ; write 0AAh

BSF EECON1, WR ; start erase (CPU stall)

BSF INTCON, GIE ; re-enable interrupts

PIC18F2585/2680/4585/4680

6.5 Writing to Flash Program Memory

The minimum programming block is 32 words or

64 bytes. Word or byte programming is not supported.

Table writes are used internally to load the holding

registers needed to program the Flash memory. There

are 64 holding registers used by the table writes for

programming.

Since the Table Latch (TABLAT) is only a single byte,

the TBLWT instruction may need to be executed 64

times for each programming operation. All of the table

write operations will essentially be short writes because

only the holding registers are written. At the end of

updating the 64 holding registers, the EECON1 register

must be written to in order to start the programming

operation with a long write.

The long write is necessary for programming the

internal Flash. Instruction execution is halted while in a

long write cycle. The long write will be terminated by

the internal programming timer.

The EEPROM on-chip timer controls the write time.

The write/erase voltages are generated by an on-chip

charge pump, rated to operate over the voltage range

of the device.

FIGURE 6-5: TABLE WRITES TO FLASH PROGRAM MEMORY

6.5.1 FLASH PROGRAM MEMORY WRITE

SEQUENCE

The sequence of events for programming an internal

program memory location should be:

1. Read 64 bytes into RAM.

2. Update data values in RAM as necessary.

3. Load Table Pointer register with address being

erased.

4. Execute the row erase procedure.

5. Load Table Pointer register with address of first

byte being written.

6. Write the 64 bytes into the holding registers with

auto-increment.

7. Set the EECON1 register for the write operation:

• set EEPGD bit to point to program memory;

• clear the CFGS bit to access program memory;

• set WREN to enable byte writes.

8. Disable interrupts.

9. Write 55h to EECON2.

10. Write 0AAh to EECON2.

11. Set the WR bit. This will begin the write cycle.

12. The CPU will stall for duration of the write (about

2 ms using internal timer).

13. Re-enable interrupts.

14. Verify the memory (table read).

This procedure will require about 18 ms to update one

row of 64 bytes of memory. An example of the required

code is given in Example 6-3.

Note: The default value of the holding registers on

device Resets and after write operations is

FFh. A write of FFh to a holding register

does not modify that byte. This means that

individual bytes of program memory may be

modified, provided that the change does not

attempt to change any bit from a ‘0’ to a ‘1’.

When modifying individual bytes, it is not

necessary to load all 64 holding registers

before executing a write operation.

TBLPTR = xxxx3FTBLPTR = xxxxx1TBLPTR = xxxxx0 TBLPTR = xxxxx2

Program Memory

Holding Register Holding Register Holding Register Holding Register

88 8 8

TABLAT

Write Register

Note: Before setting the WR bit, the Table

Pointer address needs to be within the

intended address range of the 64 bytes in

the holding register.

PIC18F2585/2680/4585/4680

EXAMPLE 6-3: WRITING TO FLASH PROGRAM MEMORY

MOVLW D'64 ; number of bytes in erase block

MOVWF COUNTER

MOVLW BUFFER_ADDR_HIGH ; point to buffer

MOVWF FSR0H

MOVLW BUFFER_ADDR_LOW

MOVWF FSR0L

MOVLW CODE_ADDR_UPPER ; Load TBLPTR with the base

MOVWF TBLPTRU ; address of the memory block

MOVLW CODE_ADDR_HIGH

MOVWF TBLPTRH

MOVLW CODE_ADDR_LOW

MOVWF TBLPTRL

READ_BLOCK

TBLRD*+ ; read into TABLAT, and inc

MOVF TABLAT, W ; get data

MOVWF POSTINC0 ; store data

DECFSZ COUNTER ; done?

BRA READ_BLOCK ; repeat

MODIFY_WORD

MOVLW DATA_ADDR_HIGH ; point to buffer

MOVWF FSR0H

MOVLW DATA_ADDR_LOW

MOVWF FSR0L

MOVLW NEW_DATA_LOW ; update buffer word

MOVWF POSTINC0

MOVLW NEW_DATA_HIGH

MOVWF INDF0

ERASE_BLOCK

MOVLW CODE_ADDR_UPPER ; load TBLPTR with the base

MOVWF TBLPTRU ; address of the memory block

MOVLW CODE_ADDR_HIGH

MOVWF TBLPTRH

MOVLW CODE_ADDR_LOW

MOVWF TBLPTRL

BSF EECON1, EEPGD ; point to Flash program memory

BCF EECON1, CFGS ; access Flash program memory

BSF EECON1, WREN ; enable write to memory

BSF EECON1, FREE ; enable Row Erase operation

BCF INTCON, GIE ; disable interrupts

MOVLW 55h

Required MOVWF EECON2 ; write 55h

Sequence MOVLW 0AAh

MOVWF EECON2 ; write 0AAh

BSF EECON1, WR ; start erase (CPU stall)

BSF INTCON, GIE ; re-enable interrupts

TBLRD*- ; dummy read decrement

MOVLW BUFFER_ADDR_HIGH ; point to buffer

MOVWF FSR0H

MOVLW BUFFER_ADDR_LOW

MOVWF FSR0L

WRITE_BUFFER_BACK

MOVLW D’64 ; number of bytes in holding register

MOVWF COUNTER

WRITE_BYTE_TO_HREGS

MOVF POSTINC0, W ; get low byte of buffer data

MOVWF TABLAT ; present data to table latch

TBLWT+* ; write data, perform a short write

; to internal TBLWT holding register.

DECFSZ COUNTER ; loop until buffers are full

BRA WRITE_BYTE_TO_HREGS

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 103
PIC18F2585/2680/4585/4680
EXAMPLE 6-3: WRITING TO FLASH PROGRAM MEMORY (CONTINUED)
6.5.2 WRITE VERIFY
Depending on the application, good programming
practice may dictate that the value written to the
memory should be verified against the original value.
This should be used in applications where excessive
writes can stress bits near the specification limit.
6.5.3 UNEXPECTED TERMINATION OF 
WRITE OPERATION
If a write is terminated by an unplanned event, such as
loss of power or an unexpected Reset, the memory
location just programmed should be verified and repro-
grammed if needed. If the write operation is interrupted
by a MCLR Reset or a WDT Time-out Reset during
normal operation, the user can check the WRERR bit
and rewrite the location(s) as needed.
6.5.4 PROTECTION AGAINST SPURIOUS 
WRITES
To protect against spurious writes to Flash program
memory, the write initiate sequence must also be
followed. See Section 24.0 “Special Features of the
CPU” for more detail.
6.6 Flash Program Operation During 
Code Protection
See  Section 24.5 “Program Verification and Code
Protection” for details on code protection of Flash
program memory.
TABLE 6-2: REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY 
PROGRAM_MEMORY
BSF EECON1, EEPGD ; point to Flash program memory
BCF EECON1, CFGS ; access Flash program memory
BSF EECON1, WREN ; enable write to memory
BCF INTCON, GIE ; disable interrupts
MOVLW 55h
Required MOVWF EECON2 ; write 55h
Sequence MOVLW 0AAh
MOVWF EECON2  ; write 0AAh
BSF EECON1, WR ; start program (CPU stall)
BSF INTCON, GIE ; re-enable interrupts
BCF EECON1, WREN ; disable write to memory
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values  on 
page
TBLPTRU —— bit21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) 49
TBPLTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) 49
TBLPTRL Program Memory Table Pointer High Byte (TBLPTR<7:0>) 49
TABLAT Program Memory Table Latch 49
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
EECON2 EEPROM Control Register 2 (not a physical register) 51
EECON1 EEPGD CFGS — FREE WRERR WREN WR RD 51
IPR2 OSCFIP CMIP(1) — EEIP BCLIP HLVDIP TMR3IP ECCP1IP(1) 51
PIR2 OSCFIF CMIF(1) — EEIF BCLIF HLVDIF TMR3IF ECCP1IF(1) 51
PIE2 OSCFIE CMIE(1) — EEIE BCLIE HLVDIE TMR3IE ECCP1IE(1) 52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1: These bits are available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

7.0 DATA EEPROM MEMORY

The data EEPROM is a nonvolatile memory array,

separate from the data RAM and program memory, that

is used for long-term storage of program data. It is not

directly mapped in either the register file or program

memory space but is indirectly addressed through the

Special Function Registers (SFRs). The EEPROM is

readable and writable during normal operation over the

entire VDD range.

Five SFRs are used to read and write to the data

EEPROM as well as the program memory. They are:

• EECON1

• EECON2

• EEDATA

• EEADR

• EEADRH

The data EEPROM allows byte read and write. When

interfacing to the data memory block, EEDATA holds

the 8-bit data for read/write and the EEADRH:EEADR

being accessed.

The EEPROM data memory is rated for high erase/write

cycle endurance. A byte write automatically erases the

location and writes the new data (erase-before-write).

The write time is controlled by an on-chip timer; it will

vary with voltage and temperature, as well as from chip

to chip. Please refer to parameter D122 (Table 27-1 in

Section 27.0 “Electrical Characteristics”) for exact

limits.

7.1 EEADR and EEADRH Registers

The EEADRH:EEADR register pair is used to address

the data EEPROM for read and write operations.

EEADRH holds the two MSbits of the address; the

upper 6 bits are ignored. The 10-bit range of the pair

can address a memory range of 1024 bytes (00h to

3FFh).

7.2 EECON1 and EECON2 Registers

Access to the data EEPROM is controlled by two

registers: EECON1 and EECON2. These are the same

registers which control access to the program memory

and are used in a similar manner for the data

EEPROM.

The EECON1 register (Register 7-1) is the control

bit EEPGD determines if the access will be to program

or data EEPROM memory. When clear, operations will

access the data EEPROM memory. When set, program

memory is accessed.

Control bit CFGS determines if the access will be to the

Configuration registers or to program memory/data

EEPROM memory. When set, subsequent operations

access Configuration registers. When CFGS is clear,

the EEPGD bit selects either program Flash or data

EEPROM memory.

The WREN bit, when set, will allow a write operation.

On power-up, the WREN bit is clear. The WRERR bit is

set in hardware when the WREN bit is set and cleared

when the internal programming timer expires and the

write operation is complete.

The WR control bit initiates write operations. The bit

cannot be cleared, only set, in software; it is cleared in

hardware at the completion of the write operation.

Control bits, RD and WR, start read and erase/write

operations, respectively. These bits are set by firmware

and cleared by hardware at the completion of the

operation.

The RD bit cannot be set when accessing program

memory (EEPGD = 1). Program memory is read using

table read instructions. See Section 6.1 “Table Reads

and Table Writes” regarding table reads.

The EECON2 register is not a physical register. It is

used exclusively in the memory write and erase

sequences. Reading EECON2 will read all ‘0’s.

Note: During normal operation, the WRERR is

read as ‘1’. This can indicate that a write

operation was prematurely terminated by

a Reset, or a write operation was

attempted improperly.

Note: The EEIF interrupt flag bit (PIR2<4>) is set

when the write is complete. It must be

cleared in software.

PIC18F2585/2680/4585/4680

R/W-x R/W-x U-0 R/W-0 R/W-x R/W-0 R/S-0 R/S-0

EEPGD CFGS — FREE WRERR WREN WR RD

bit 7 bit 0

bit 7 EEPGD: Flash Program or Data EEPROM Memory Select bit

1 = Access Flash program memory

0 = Access data EEPROM memory

bit 6 CFGS: Flash Program/Data EEPROM or Configuration Select bit

1 = Access Configuration registers

0 = Access Flash program or data EEPROM memory

bit 5 Unimplemented: Read as ‘0’

bit 4 FREE: Flash Row Erase Enable bit

1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared

by completion of erase operation)

0 = Perform write only

bit 3 WRERR: Flash Program/Data EEPROM Error Flag bit

1 = A write operation is prematurely terminated (any Reset during self-timed programming in

normal operation, or an improper write attempt)

0 = The write operation completed

Note: When a WRERR occurs, the EEPGD and CFGS bits are not cleared.

This allows tracing of the error condition.

bit 2 WREN: Flash Program/Data EEPROM Write Enable bit

1 = Allows write cycles to Flash program/data EEPROM

0 = Inhibits write cycles to Flash program/data EEPROM

bit 1 WR: Write Control bit

1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle

(The operation is self-timed and the bit is cleared by hardware once write is complete.

The WR bit can only be set (not cleared) in software.)

0 = Write cycle to the EEPROM is complete

bit 0 RD: Read Control bit

1 = Initiates an EEPROM read

(Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared)

in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.)

0 = Does not initiate an EEPROM read

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

7.3 Reading the Data EEPROM

Memory

To read a data memory location, the user must write the

address to the EEADRH:EEADR register pair, clear the

EEPGD control bit (EECON1<7>) and then set control

bit, RD (EECON1<0>). The data is available on the

very next instruction cycle; therefore, the EEDATA

will hold this value until another read operation, or until

it is written to by the user (during a write operation).

The basic process is shown in Example 7-1.

7.4 Writing to the Data EEPROM

Memory

To write an EEPROM data location, the address must

first be written to the EEADRH:EEADR register pair

and the data written to the EEDATA register. The

sequence in Example 7-2 must be followed to initiate

the write cycle.

The write will not begin if this sequence is not exactly

followed (write 55h to EECON2, write 0AAh to

EECON2, then set WR bit) for each byte. It is strongly

recommended that interrupts be disabled during this

code segment.

Additionally, the WREN bit in EECON1 must be set to

enable writes. This mechanism prevents accidental

writes to data EEPROM due to unexpected code

execution (i.e., runaway programs). The WREN bit

should be kept clear at all times, except when updating

the EEPROM. The WREN bit is not cleared

by hardware.

After a write sequence has been initiated, EECON1,

EEADRH:EEADR and EEDATA cannot be modified.

The WR bit will be inhibited from being set unless the

WREN bit is set. The WREN bit must be set on a

previous instruction. Both WR and WREN cannot be

set with the same instruction.

At the completion of the write cycle, the WR bit is

cleared in hardware and the EEPROM Interrupt Flag bit

(EEIF) is set. The user may either enable this interrupt,

or poll this bit. EEIF must be cleared by software.

7.5 Write Verify

Depending on the application, good programming

practice may dictate that the value written to the

memory should be verified against the original value.

This should be used in applications where excessive

writes can stress bits near the specification limit.

EXAMPLE 7-1: DATA EEPROM READ

EXAMPLE 7-2: DATA EEPROM WRITE

MOVLW DATA_EE_ADDRH ;

MOVWF EEADRH ; Upper bits of Data Memory Address to read

MOVLW DATA_EE_ADDR ;

MOVWF EEADR ; Lower bits of Data Memory Address to read

BCF EECON1, EEPGD ; Point to DATA memory

BCF EECON1, CFGS ; Access EEPROM

BSF EECON1, RD ; EEPROM Read

MOVF EEDATA, W ; W = EEDATA

MOVLW DATA_EE_ADDRH ;

MOVWF EEADRH ; Upper bits of Data Memory Address to write

MOVLW DATA_EE_ADDR ;

MOVWF EEADR ; Lower bits of Data Memory Address to write

MOVLW DATA_EE_DATA ;

MOVWF EEDATA ; Data Memory Value to write

BCF EECON1, EPGD ; Point to DATA memory

BCF EECON1, CFGS ; Access EEPROM

BSF EECON1, WREN ; Enable writes

BCF INTCON, GIE ; Disable Interrupts

MOVLW 55h ;

Required MOVWF EECON2 ; Write 55h

Sequence MOVLW 0AAh ;

MOVWF EECON2 ; Write 0AAh

BSF EECON1, WR ; Set WR bit to begin write

BSF INTCON, GIE ; Enable Interrupts

; User code execution

BCF EECON1, WREN ; Disable writes on write complete (EEIF set)

PIC18F2585/2680/4585/4680

7.6 Operation During Code-Protect

Data EEPROM memory has its own code-protect bits in

Configuration Words. External read and write

operations are disabled if code protection is enabled.

The microcontroller itself can both read and write to the

internal Data EEPROM, regardless of the state of the

code-protect Configuration bit. Refer to Section 24.0

“Special Features of the CPU” for additional

information.

7.7 Protection Against Spurious Write

There are conditions when the device may not want to

write to the data EEPROM memory. To protect against

spurious EEPROM writes, various mechanisms have

been implemented. On power-up, the WREN bit is

cleared. In addition, writes to the EEPROM are blocked

during the Power-up Timer period (TPWRT,

parameter 33).

The write initiate sequence and the WREN bit together

help prevent an accidental write during brown-out,

power glitch or software malfunction.

7.8 Using the Data EEPROM

The data EEPROM is a high endurance, byte address-

able array that has been optimized for the storage of

frequently changing information (e.g., program

variables or other data that are updated often).

Frequently changing values will typically be updated

more often than specification D124. If this is not the

case, an array refresh must be performed. For this

reason, variables that change infrequently (such as

constants, IDs, calibration, etc.) should be stored in

Flash program memory.

A simple data EEPROM refresh routine is shown in

Example 7-3.

EXAMPLE 7-3: DATA EEPROM REFRESH ROUTINE

Note: If data EEPROM is only used to store

constants and/or data that changes rarely,

an array refresh is likely not required. See

specification D124.

CLRF EEADR ; Start at address 0

CLRF EEADRH ;

BCF EECON1, CFGS ; Set for memory

BCF EECON1, EEPGD ; Set for Data EEPROM

BCF INTCON, GIE ; Disable interrupts

BSF EECON1, WREN ; Enable writes

Loop ; Loop to refresh array

BSF EECON1, RD ; Read current address

MOVLW 55h ;

MOVWF EECON2 ; Write 55h

MOVLW 0AAh ;

MOVWF EECON2 ; Write 0AAh

BSF EECON1, WR ; Set WR bit to begin write

BTFSC EECON1, WR ; Wait for write to complete

BRA $-2

INCFSZ EEADR, F ; Increment address

BRA LOOP ; Not zero, do it again

INCFSZ EEADRH, F ; Increment the high address

BRA LOOP ; Not zero, do it again

BCF EECON1, WREN ; Disable writes

BSF INTCON, GIE ; Enable interrupts

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 109
PIC18F2585/2680/4585/4680
TABLE 7-1: REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY 
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
EEADRH — — — — — — EEPROM Address 
Register High Byte
51
EEADR EEPROM Address Register 51
EEDATA EEPROM Data Register 51
EECON2 EEPROM Control Register 2 (not a physical register) 51
EECON1 EEPGD CFGS — FREE WRERR WREN WR RD 51
IPR2 OSCFIP CMIP(1) — EEIP BCLIP HLVDIP TMR3IP ECCP1IP(1) 51
PIR2 OSCFIF CMIF(1) — EEIF BCLIF HLVDIF TMR3IF ECCP1IF(1) 51
PIE2 OSCFIE CMIE(1) — EEIE BCLIE HLVDIE TMR3IE ECCP1IE(1) 52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during Flash/EEPROM access.
Note 1: These bits are available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

8.0 8 x 8 HARDWARE MULTIPLIER

8.1 Introduction

All PIC18 devices include an 8 x 8 hardware multiplier

as part of the ALU. The multiplier performs an unsigned

operation and yields a 16-bit result that is stored in the

product register pair, PRODH:PRODL. The multiplier’s

operation does not affect any flags in the STATUS

Making multiplication a hardware operation allows it to

be completed in a single instruction cycle. This has the

advantages of higher computational throughput and

reduced code size for multiplication algorithms and

allows the PIC18 devices to be used in many applica-

tions previously reserved for digital signal processors.

A comparison of various hardware and software

multiply operations, along with the savings in memory

and execution time, is shown in Table 8-1.

8.2 Operation

Example 8-1 shows the instruction sequence for an

8 x 8 unsigned multiplication. Only one instruction is

required when one of the arguments is already loaded

in the WREG register.

Example 8-2 shows the sequence to do an 8 x 8 signed

multiplication. To account for the signed bits of the

arguments, each argument’s Most Significant bit (MSb)

is tested and the appropriate subtractions are done.

EXAMPLE 8-1: 8 x 8 UNSIGNED

MULTIPLY ROUTINE

EXAMPLE 8-2: 8 x 8 SIGNED MULTIPLY

ROUTINE

TABLE 8-1: PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS

MOVF ARG1, W ;

MULWF ARG2 ; ARG1 * ARG2 ->

; PRODH:PRODL

MOVF ARG1, W

MULWF ARG2 ; ARG1 * ARG2 ->

; PRODH:PRODL

BTFSC ARG2, SB ; Test Sign Bit

SUBWF PRODH, F ; PRODH = PRODH

; - ARG1

MOVF ARG2, W

BTFSC ARG1, SB ; Test Sign Bit

SUBWF PRODH, F ; PRODH = PRODH

; - ARG2

Routine Multiply Method

Program

Memory

(Words)

Cycles

(Max)

Time

@ 40 MHz @ 10 MHz @ 4 MHz

8 x 8 unsigned Without hardware multiply 13 69 6.9 μs27.6 μs69 μs

Hardware multiply 1 1 100 ns 400 ns 1 μs

8 x 8 signed Without hardware multiply 33 91 9.1 μs36.4 μs91 μs

Hardware multiply 6 6 600 ns 2.4 μs6 μs

16 x 16 unsigned Without hardware multiply 21 242 24.2 μs96.8 μs 242 μs

Hardware multiply 28 28 2.8 μs 11.2 μs28 μs

16 x 16 signed Without hardware multiply 52 254 25.4 μs 102.6 μs 254 μs

Hardware multiply 35 40 4.0 μs16.0 μs40 μs

PIC18F2585/2680/4585/4680

Example 8-3 shows the sequence to do a 16 x 16

unsigned multiplication. Equation 8-1 shows the

algorithm that is used. The 32-bit result is stored in four

registers (RES3:RES0).

EQUATION 8-1: 16 x 16 UNSIGNED

MULTIPLICATION

ALGORITHM

EXAMPLE 8-3: 16 x 16 UNSIGNED

MULTIPLY ROUTINE

Example 8-4 shows the sequence to do a 16 x 16

signed multiply. Equation 8-2 shows the algorithm

used. The 32-bit result is stored in four registers

(RES3:RES0). To account for the signed bits of the

arguments, the MSb for each argument pair is tested

and the appropriate subtractions are done.

EQUATION 8-2: 16 x 16 SIGNED

MULTIPLICATION

ALGORITHM

EXAMPLE 8-4: 16 x 16 SIGNED

MULTIPLY ROUTINE

RES3:RES0 = ARG1H:ARG1L • ARG2H:ARG2L

= (ARG1H • ARG2H • 216) +

(ARG1H • ARG2L • 28) +

(ARG1L • ARG2H • 28) +

(ARG1L • ARG2L)

MOVF ARG1L, W

MULWF ARG2L ; ARG1L * ARG2L->

; PRODH:PRODL

MOVFF PRODH, RES1 ;

MOVFF PRODL, RES0 ;

;

MOVF ARG1H, W

MULWF ARG2H ; ARG1H * ARG2H->

; PRODH:PRODL

MOVFF PRODH, RES3 ;

MOVFF PRODL, RES2 ;

;

MOVF ARG1L, W

MULWF ARG2H ; ARG1L * ARG2H->

; PRODH:PRODL

MOVF PRODL, W ;

ADDWF RES1, F ; Add cross

MOVF PRODH, W ; products

ADDWFC RES2, F ;

CLRF WREG ;

ADDWFC RES3, F ;

;

MOVF ARG1H, W ;

MULWF ARG2L ; ARG1H * ARG2L->

; PRODH:PRODL

MOVF PRODL, W ;

ADDWF RES1, F ; Add cross

MOVF PRODH, W ; products

ADDWFC RES2, F ;

CLRF WREG ;

ADDWFC RES3, F ;

RES3:RES0 = ARG1H:ARG1L • ARG2H:ARG2L

= (ARG1H • ARG2H • 216) +

(ARG1H • ARG2L • 28) +

(ARG1L • ARG2H • 28) +

(ARG1L • ARG2L) +

(-1 • ARG2H<7> • ARG1H:ARG1L • 216) +

(-1 • ARG1H<7> • ARG2H:ARG2L • 216)

MOVF ARG1L, W

MULWF ARG2L ; ARG1L * ARG2L ->

; PRODH:PRODL

MOVFF PRODH, RES1 ;

MOVFF PRODL, RES0 ;

;

MOVF ARG1H, W

MULWF ARG2H ; ARG1H * ARG2H ->

; PRODH:PRODL

MOVFF PRODH, RES3 ;

MOVFF PRODL, RES2 ;

;

MOVF ARG1L,W

MULWF ARG2H ; ARG1L * ARG2H ->

; PRODH:PRODL

MOVF PRODL, W ;

ADDWF RES1, F ; Add cross

MOVF PRODH, W ; products

ADDWFC RES2, F ;

CLRF WREG ;

ADDWFC RES3, F ;

;

MOVF ARG1H, W ;

MULWF ARG2L ; ARG1H * ARG2L ->

; PRODH:PRODL

MOVF PRODL, W ;

ADDWF RES1, F ; Add cross

MOVF PRODH, W ; products

ADDWFC RES2, F ;

CLRF WREG ;

ADDWFC RES3, F ;

;

BTFSS ARG2H, 7 ; ARG2H:ARG2L neg?

BRA SIGN_ARG1 ; no, check ARG1

MOVF ARG1L, W ;

SUBWF RES2 ;

MOVF ARG1H, W ;

SUBWFB RES3

;

SIGN_ARG1

BTFSS ARG1H, 7 ; ARG1H:ARG1L neg?

BRA CONT_CODE ; no, done

MOVF ARG2L, W ;

SUBWF RES2 ;

MOVF ARG2H, W ;

SUBWFB RES3

;

CONT_CODE

PIC18F2585/2680/4585/4680

9.0 INTERRUPTS

The PIC18F2585/2680/4585/4680 devices have multi-

ple interrupt sources and an interrupt priority feature

that allows each interrupt source to be assigned a high

priority level or a low priority level. The high priority

interrupt vector is at 000008h and the low priority

interrupt vector is at 000018h. High priority interrupt

events will interrupt any low priority interrupts that may

be in progress.

There are ten registers which are used to control

interrupt operation. These registers are:

• RCON

•INTCON

• INTCON2

• INTCON3

• PIR1, PIR2, PIR3

• PIE1, PIE2, PIE3

• IPR1, IPR2, IPR3

It is recommended that the Microchip header files

supplied with MPLAB® IDE be used for the symbolic bit

names in these registers. This allows the assembler/

compiler to automatically take care of the placement of

these bits within the specified register.

Each interrupt source has three bits to control its

operation. The functions of these bits are:

• Flag bit to indicate that an interrupt event

occurred

• Enable bit that allows program execution to

branch to the interrupt vector address when the

flag bit is set

• Priority bit to select high priority or low priority

The interrupt priority feature is enabled by setting the

IPEN bit (RCON<7>). When interrupt priority is

enabled, there are two bits which enable interrupts

globally. Setting the GIEH bit (INTCON<7>) enables all

interrupts that have the priority bit set (high priority).

Setting the GIEL bit (INTCON<6>) enables all

interrupts that have the priority bit cleared (low priority).

When the interrupt flag, enable bit and appropriate

global interrupt enable bit are set, the interrupt will

vector immediately to address 000008h or 000018h,

depending on the priority bit setting. Individual inter-

rupts can be disabled through their corresponding

enable bits.

When the IPEN bit is cleared (default state), the inter-

rupt priority feature is disabled and interrupts are com-

patible with PIC® mid-range devices. In Compatibility

mode, the interrupt priority bits for each source have no

effect. INTCON<6> is the PEIE bit, which enables/

disables all peripheral interrupt sources. INTCON<7>

is the GIE bit, which enables/disables all interrupt

sources. All interrupts branch to address 000008h in

Compatibility mode.

When an interrupt is responded to, the global interrupt

enable bit is cleared to disable further interrupts. If the

IPEN bit is cleared, this is the GIE bit. If interrupt priority

levels are used, this will be either the GIEH or GIEL bit.

High priority interrupt sources can interrupt a low

priority interrupt. Low priority interrupts are not

processed while high priority interrupts are in progress.

The return address is pushed onto the stack and the

PC is loaded with the interrupt vector address

(000008h or 000018h). Once in the Interrupt Service

Routine, the source(s) of the interrupt can be deter-

mined by polling the interrupt flag bits. The interrupt

flag bits must be cleared in software before re-enabling

interrupts to avoid recursive interrupts.

The “return from interrupt” instruction, RETFIE, exits

the interrupt routine and sets the GIE bit (GIEH or GIEL

if priority levels are used), which re-enables interrupts.

For external interrupt events, such as the INT pins or

the PORTB input change interrupt, the interrupt latency

will be three to four instruction cycles. The exact

latency is the same for one or two-cycle instructions.

Individual interrupt flag bits are set, regardless of the

status of their corresponding enable bit or the GIE bit.

Note: Do not use the MOVFF instruction to modify

any of the interrupt control registers while

any interrupt is enabled. Doing so may

cause erratic microcontroller behavior.

PIC18F2585/2680/4585/4680

FIGURE 9-1: INTERRUPT LOGIC

TMR0IE

GIEH/GIE

GIEL/PEIE

Wake-up if in Sleep Mode

Interrupt to CPU

Vector to Location

0008h

INT2IF

INT2IE

INT2IP

INT1IF

INT1IE

INT1IP

TMR0IF

TMR0IE

TMR0IP

RBIF

RBIE

RBIP

IPEN

TMR0IF

TMR0IP

INT1IF

INT1IE

INT1IP

INT2IF

INT2IE

INT2IP

RBIF

RBIE

RBIP

INT0IF

INT0IE

GIEL/PEIE

Interrupt to CPU

Vector to Location

IPEN

IPE

0018h

Peripheral Interrupt Flag bit

Peripheral Interrupt Enable bit

Peripheral Interrupt Priority bit

Peripheral Interrupt Flag bit

Peripheral Interrupt Enable bit

Peripheral Interrupt Priority bit

TMR1IF

TMR1IE

TMR1IP

XXXXIF

XXXXIE

XXXXIP

Additional Peripheral Interrupts

TMR1IF

TMR1IE

TMR1IP

High Priority Interrupt Generation

Low Priority Interrupt Generation

XXXXIF

XXXXIE

XXXXIP

Additional Peripheral Interrupts

GIE/GEIH

PIC18F2585/2680/4585/4680

9.1 INTCON Registers

The INTCON registers are readable and writable

registers, which contain various enable, priority and

flag bits.

Note: Interrupt flag bits are set when an interrupt

condition occurs regardless of the state of

its corresponding enable bit or the global

interrupt enable bit. User software should

ensure the appropriate interrupt flag bits

are clear prior to enabling an interrupt.

This feature allows for software polling.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-x

GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF

bit 7 bit 0

bit 7 GIE/GIEH: Global Interrupt Enable bit

When IPEN = 0:

1 = Enables all unmasked interrupts

0 = Disables all interrupts

When IPEN = 1:

1 = Enables all high priority interrupts

0 = Disables all high priority interrupts

bit 6 PEIE/GIEL: Peripheral Interrupt Enable bit

When IPEN = 0:

1 = Enables all unmasked peripheral interrupts

0 = Disables all peripheral interrupts

When IPEN = 1:

1 = Enables all low priority peripheral interrupts

0 = Disables all low priority peripheral interrupts

bit 5 TMR0IE: TMR0 Overflow Interrupt Enable bit

1 = Enables the TMR0 overflow interrupt

0 = Disables the TMR0 overflow interrupt

bit 4 INT0IE: INT0 External Interrupt Enable bit

1 = Enables the INT0 external interrupt

0 = Disables the INT0 external interrupt

bit 3 RBIE: RB Port Change Interrupt Enable bit

1 = Enables the RB port change interrupt

0 = Disables the RB port change interrupt

bit 2 TMR0IF: TMR0 Overflow Interrupt Flag bit

1 = TMR0 register has overflowed (must be cleared in software)

0 = TMR0 register did not overflow

bit 1 INT0IF: INT0 External Interrupt Flag bit

1 = The INT0 external interrupt occurred (must be cleared in software)

0 = The INT0 external interrupt did not occur

bit 0 RBIF: RB Port Change Interrupt Flag bit

1 = At least one of the RB7:RB4 pins changed state (must be cleared in software)

0 = None of the RB7:RB4 pins have changed state

Note: A mismatch condition will continue to set this bit. Reading PORTB will end the

mismatch condition and allow the bit to be cleared.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-1 R/W-1 R/W-1 R/W-1 U-0 R/W-1 U-0 R/W-1

RBPU INTEDG0 INTEDG1 INTEDG2 —TMR0IP—RBIP

bit 7 bit 0

bit 7 RBPU: PORTB Pull-up Enable bit

1 = All PORTB pull-ups are disabled

0 = PORTB pull-ups are enabled by individual port latch values

bit 6 INTEDG0: External Interrupt 0 Edge Select bit

1 = Interrupt on rising edge

0 = Interrupt on falling edge

bit 5 INTEDG1: External Interrupt 1 Edge Select bit

1 = Interrupt on rising edge

0 = Interrupt on falling edge

bit 4 INTEDG2: External Interrupt 2 Edge Select bit

1 = Interrupt on rising edge

0 = Interrupt on falling edge

bit 3 Unimplemented: Read as ‘0’

bit 2 TMR0IP: TMR0 Overflow Interrupt Priority bit

1 = High priority

0 = Low priority

bit 1 Unimplemented: Read as ‘0’

bit 0 RBIP: RB Port Change Interrupt Priority bit

1 = High priority

0 = Low priority

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Note: Interrupt flag bits are set when an interrupt condition occurs regardless of the state

of its corresponding enable bit or the global interrupt enable bit. User software

should ensure the appropriate interrupt flag bits are clear prior to enabling an

interrupt. This feature allows for software polling.

PIC18F2585/2680/4585/4680

R/W-1 R/W-1 U-0 R/W-0 R/W-0 U-0 R/W-0 R/W-0

INT2IP INT1IP —INT2IEINT1IE— INT2IF INT1IF

bit 7 bit 0

bit 7 INT2IP: INT2 External Interrupt Priority bit

1 = High priority

0 = Low priority

bit 6 INT1IP: INT1 External Interrupt Priority bit

1 = High priority

0 = Low priority

bit 5 Unimplemented: Read as ‘0’

bit 4 INT2IE: INT2 External Interrupt Enable bit

1 = Enables the INT2 external interrupt

0 = Disables the INT2 external interrupt

bit 3 INT1IE: INT1 External Interrupt Enable bit

1 = Enables the INT1 external interrupt

0 = Disables the INT1 external interrupt

bit 2 Unimplemented: Read as ‘0’

bit 1 INT2IF: INT2 External Interrupt Flag bit

1 = The INT2 external interrupt occurred (must be cleared in software)

0 = The INT2 external interrupt did not occur

bit 0 INT1IF: INT1 External Interrupt Flag bit

1 = The INT1 external interrupt occurred (must be cleared in software)

0 = The INT1 external interrupt did not occur

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Note: Interrupt flag bits are set when an interrupt condition occurs regardless of the state

of its corresponding enable bit or the global interrupt enable bit. User software

should ensure the appropriate interrupt flag bits are clear prior to enabling an

interrupt. This feature allows for software polling.

PIC18F2585/2680/4585/4680

9.2 PIR Registers

The PIR registers contain the individual flag bits for the

peripheral interrupts. Due to the number of peripheral

interrupt sources, there are two Peripheral Interrupt

Request (Flag) registers (PIR1, PIR2).

Note 1: Interrupt flag bits are set when an interrupt

condition occurs regardless of the state of

its corresponding enable bit or the global

interrupt enable bit, GIE (INTCON<7>).

2: User software should ensure the appropri-

ate interrupt flag bits are cleared prior to

enabling an interrupt and after servicing

that interrupt.

R/W-0 R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0

PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF

bit 7 bit 0

bit 7 PSPIF: Parallel Slave Port Read/Write Interrupt Flag bit(1)

1 = A read or a write operation has taken place (must be cleared in software)

0 = No read or write has occurred

Note 1: This bit is reserved on PIC18F2X8X devices; always maintain this bit clear.

bit 6 ADIF: A/D Converter Interrupt Flag bit

1 = An A/D conversion completed (must be cleared in software)

0 = The A/D conversion is not complete

bit 5 RCIF: EUSART Receive Interrupt Flag bit

1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read)

0 = The EUSART receive buffer is empty

bit 4 TXIF: EUSART Transmit Interrupt Flag bit

1 = The EUSART transmit buffer, TXREG, is empty (cleared when TXREG is written)

0 = The EUSART transmit buffer is full

bit 3 SSPIF: Master Synchronous Serial Port Interrupt Flag bit

1 = The transmission/reception is complete (must be cleared in software)

0 = Waiting to transmit/receive

bit 2 CCP1IF: CCP1 Interrupt Flag bit

Capture mode:

1 = A TMR1 register capture occurred (must be cleared in software)

0 = No TMR1 register capture occurred

Compare mode:

1 = A TMR1 register compare match occurred (must be cleared in software)

0 = No TMR1 register compare match occurred

PWM mode:

Unused in this mode.

bit 1 TMR2IF: TMR2 to PR2 Match Interrupt Flag bit

1 = TMR2 to PR2 match occurred (must be cleared in software)

0 = No TMR2 to PR2 match occurred

bit 0 TMR1IF: TMR1 Overflow Interrupt Flag bit

1 = TMR1 register overflowed (must be cleared in software)

0 = MR1 register did not overflow

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

OSCFIF CMIF(1) — EEIF BCLIF HLVDIF TMR3IF ECCP1IF(1)

bit 7 bit 0

bit 7 OSCFIF: Oscillator Fail Interrupt Flag bit

1 = System oscillator failed, clock input has changed to INTOSC (must be cleared in software)

0 = System clock operating

bit 6 CMIF: Comparator Interrupt Flag bit(1)

1 = Comparator input has changed (must be cleared in software)

0 = Comparator input has not changed

bit 5 Unimplemented: Read as ‘0’

bit 4 EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit

1 = The write operation is complete (must be cleared in software)

0 = The write operation is not complete, or has not been started

bit 3 BCLIF: Bus Collision Interrupt Flag bit

1 = A bus collision occurred (must be cleared in software)

0 = No bus collision occurred

bit 2 HLVDIF: High/Low-Voltage Detect Interrupt Flag bit

1 = A low-voltage condition occurred (must be cleared in software)

0 = The device voltage is above the High/Low-Voltage Detect trip point

bit 1 TMR3IF: TMR3 Overflow Interrupt Flag bit

1 = TMR3 register overflowed (must be cleared in software)

0 = TMR3 register did not overflow

bit 0 ECCP1IF: ECCP1 Interrupt Flag bit(1)

Capture mode:

1 = A TMR1 register capture occurred (must be cleared in software)

0 = No TMR1 register capture occurred

Compare mode:

1 = A TMR1 register compare match occurred (must be cleared in software)

0 = No TMR1 register compare match occurred

PWM mode:

Unused in this mode.

Note 1: These bits are available in PIC18F4X8X and reserved in PIC18F2X8X devices.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIF WAKIF ERRIF TXB2IF TXB1IF(1) TXB0IF(1) RXB1IF RXB0IF

Mode 1, 2 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIF WAKIF ERRIF TXBnIF TXB1IF(1) TXB0IF(1) RXBnIF FIFOWMIF

bit 7 bit 0

bit 7 IRXIF: CAN Invalid Received Message Interrupt Flag bit

1 = An invalid message has occurred on the CAN bus

0 = No invalid message on CAN bus

bit 6 WAKIF: CAN bus Activity Wake-up Interrupt Flag bit

1 = Activity on CAN bus has occurred

0 = No activity on CAN bus

bit 5 ERRIF: CAN bus Error Interrupt Flag bit

1 = An error has occurred in the CAN module (multiple sources)

0 = No CAN module errors

bit 4 When CAN is in Mode 0:

TXB2IF: CAN Transmit Buffer 2 Interrupt Flag bit

1 = Transmit Buffer 2 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 2 has not completed transmission of a message

When CAN is in Mode 1 or 2:

TXBnIF: Any Transmit Buffer Interrupt Flag bit

1 = One or more transmit buffers have completed transmission of a message and may be

reloaded

0 = No transmit buffer is ready for reload

bit 3 TXB1IF: CAN Transmit Buffer 1 Interrupt Flag bit(1)

1 = Transmit Buffer 1 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 1 has not completed transmission of a message

bit 2 TXB0IF: CAN Transmit Buffer 0 Interrupt Flag bit(1)

1 = Transmit Buffer 0 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 0 has not completed transmission of a message

bit 1 When CAN is in Mode 0:

RXB1IF: CAN Receive Buffer 1 Interrupt Flag bit

1 = Receive Buffer 1 has received a new message

0 = Receive Buffer 1 has not received a new message

When CAN is in Mode 1 or 2:

RXBnIF: Any Receive Buffer Interrupt Flag bit

1 = One or more receive buffers has received a new message

0 = No receive buffer has received a new message

bit 0 When CAN is in Mode 0:

RXB0IF: CAN Receive Buffer 0 Interrupt Flag bit

1 = Receive Buffer 0 has received a new message

0 = Receive Buffer 0 has not received a new message

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIF: FIFO Watermark Interrupt Flag bit

1 = FIFO high watermark is reached

0 = FIFO high watermark is not reached

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

9.3 PIE Registers

The PIE registers contain the individual enable bits for

the peripheral interrupts. Due to the number of

peripheral interrupt sources, there are two Peripheral

Interrupt Enable registers (PIE1, PIE2). When IPEN = 0,

the PEIE bit must be set to enable any of these

peripheral interrupts.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE

bit 7 bit 0

bit 7 PSPIE: Parallel Slave Port Read/Write Interrupt Enable bit(1)

1 = Enables the PSP read/write interrupt

0 = Disables the PSP read/write interrupt

Note 1: This bit is reserved on PIC18F2X8X devices; always maintain this bit clear.

bit 6 ADIE: A/D Converter Interrupt Enable bit

1 = Enables the A/D interrupt

0 = Disables the A/D interrupt

bit 5 RCIE: EUSART Receive Interrupt Enable bit

1 = Enables the EUSART receive interrupt

0 = Disables the EUSART receive interrupt

bit 4 TXIE: EUSART Transmit Interrupt Enable bit

1 = Enables the EUSART transmit interrupt

0 = Disables the EUSART transmit interrupt

bit 3 SSPIE: Master Synchronous Serial Port Interrupt Enable bit

1 = Enables the MSSP interrupt

0 = Disables the MSSP interrupt

bit 2 CCP1IE: CCP1 Interrupt Enable bit

1 = Enables the CCP1 interrupt

0 = Disables the CCP1 interrupt

bit 1 TMR2IE: TMR2 to PR2 Match Interrupt Enable bit

1 = Enables the TMR2 to PR2 match interrupt

0 = Disables the TMR2 to PR2 match interrupt

bit 0 TMR1IE: TMR1 Overflow Interrupt Enable bit

1 = Enables the TMR1 overflow interrupt

0 = Disables the TMR1 overflow interrupt

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

OSCFIE CMIE(1) — EEIE BCLIE HLVDIE TMR3IE ECCP1IE(2)

bit 7 bit 0

bit 7 OSCFIE: Oscillator Fail Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 6 CMIE: Comparator Interrupt Enable bit(1)

1 = Enabled

0 =Disabled

bit 5 Unimplemented: Read as ‘0’

bit 4 EEIE: Data EEPROM/Flash Write Operation Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 3 BCLIE: Bus Collision Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 2 HLVDIE: High/Low-Voltage Detect Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 1 TMR3IE: TMR3 Overflow Interrupt Enable bit

1 = Enabled

0 =Disabled

bit 0 ECCP1IE: ECCP1 Interrupt Enable bit(2)

1 = Enabled

0 =Disabled

Note 1: This bit is available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.

2: This bit is available in PIC18F4X8X devices only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIE WAKIE ERRIE TXB2IE TXB1IE(1) TXB0IE(1) RXB1IE RXB0IE

Mode 1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIE WAKIE ERRIE TXBnIE TXB1IE(1) TXB0IE(1) RXBnIE FIFOWMIE

bit 7 bit 0

bit 7 IRXIE: CAN Invalid Received Message Interrupt Enable bit

1 = Enable invalid message received interrupt

0 = Disable invalid message received interrupt

bit 6 WAKIE: CAN bus Activity Wake-up Interrupt Enable bit

1 = Enable bus activity wake-up interrupt

0 = Disable bus activity wake-up interrupt

bit 5 ERRIE: CAN bus Error Interrupt Enable bit

1 = Enable CAN bus error interrupt

0 = Disable CAN bus error interrupt

bit 4 When CAN is in Mode 0:

TXB2IE: CAN Transmit Buffer 2 Interrupt Enable bit

1 = Enable Transmit Buffer 2 interrupt

0 = Disable Transmit Buffer 2 interrupt

When CAN is in Mode 1 or 2:

TXBnIE: CAN Transmit Buffer Interrupts Enable bit

1 = Enable transmit buffer interrupt; individual interrupt is enabled by TXBIE and BIE0

0 = Disable all transmit buffer interrupts

bit 3 TXB1IE: CAN Transmit Buffer 1 Interrupt Enable bit(1)

1 = Enable Transmit Buffer 1 interrupt

0 = Disable Transmit Buffer 1 interrupt

bit 2 TXB0IE: CAN Transmit Buffer 0 Interrupt Enable bit(1)

1 = Enable Transmit Buffer 0 interrupt

0 = Disable Transmit Buffer 0 interrupt

bit 1 When CAN is in Mode 0:

RXB1IE: CAN Receive Buffer 1 Interrupt Enable bit

1 = Enable Receive Buffer 1 interrupt

0 = Disable Receive Buffer 1 interrupt

When CAN is in Mode 1 or 2:

RXBnIE: CAN Receive Buffer Interrupts Enable bit

1 = Enable receive buffer interrupt; individual interrupt is enabled by BIE0

0 = Disable all receive buffer interrupts

bit 0 When CAN is in Mode 0:

RXB0IE: CAN Receive Buffer 0 Interrupt Enable bit

1 = Enable Receive Buffer 0 interrupt

0 = Disable Receive Buffer 0 interrupt

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIE: FIFO Watermark Interrupt Enable bit

1 = Enable FIFO watermark interrupt

0 = Disable FIFO watermark interrupt

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

9.4 IPR Registers

The IPR registers contain the individual priority bits for

the peripheral interrupts. Due to the number of

peripheral interrupt sources, there are two Peripheral

Interrupt Priority registers (IPR1, IPR2). Using the

priority bits requires that the Interrupt Priority Enable

(IPEN) bit be set.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP

bit 7 bit 0

bit 7 PSPIP: Parallel Slave Port Read/Write Interrupt Priority bit(1)

1 =High priority

0 = Low priority

Note 1: This bit is reserved on PIC18F2X8X devices; always maintain this bit set.

bit 6 ADIP: A/D Converter Interrupt Priority bit

1 =High priority

0 = Low priority

bit 5 RCIP: EUSART Receive Interrupt Priority bit

1 =High priority

0 = Low priority

bit 4 TXIP: EUSART Transmit Interrupt Priority bit

1 =High priority

0 = Low priority

bit 3 SSPIP: Master Synchronous Serial Port Interrupt Priority bit

1 =High priority

0 = Low priority

bit 2 CCP1IP: CCP1 Interrupt Priority bit

1 =High priority

0 = Low priority

bit 1 TMR2IP: TMR2 to PR2 Match Interrupt Priority bit

1 =High priority

0 = Low priority

bit 0 TMR1IP: TMR1 Overflow Interrupt Priority bit

1 =High priority

0 = Low priority

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-1 R/W-1 U-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

OSCFIP CMIP(1) — EEIP BCLIP HLVDIP TMR3IP ECCP1IP(2)

bit 7 bit 0

bit 7 OSCFIP: Oscillator Fail Interrupt Priority bit

1 =High priority

0 = Low priority

bit 6 CMIP: Comparator Interrupt Priority bit(1)

1 =High priority

0 = Low priority

bit 5 Unimplemented: Read as ‘0’

bit 4 EEIP: Data EEPROM/Flash Write Operation Interrupt Priority bit

1 =High priority

0 = Low priority

bit 3 BCLIP: Bus Collision Interrupt Priority bit

1 =High priority

0 = Low priority

bit 2 HLVDIP: High/Low-Voltage Detect Interrupt Priority bit

1 =High priority

0 = Low priority

bit 1 TMR3IP: TMR3 Overflow Interrupt Priority bit

1 =High priority

0 = Low priority

bit 0 ECCP1IP: ECCP1 Interrupt Priority bit(2)

1 =High priority

0 = Low priority

Note 1: This bit is available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.

2: This bit is available in PIC18F4X8X devices only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

IRXIP WAKIP ERRIP TXB2IP TXB1IP(1) TXB0IP(1) RXB1IP RXB0IP

Mode 1, 2 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

IRXIP WAKIP ERRIP TXBnIP TXB1IP(1) TXB0IP(1) RXBnIP FIFOWMIP

bit 7 bit 0

bit 7 IRXIP: CAN Invalid Received Message Interrupt Priority bit

1 = High priority

0 = Low priority

bit 6 WAKIP: CAN bus Activity Wake-up Interrupt Priority bit

1 = High priority

0 = Low priority

bit 5 ERRIP: CAN bus Error Interrupt Priority bit

1 = High priority

0 = Low priority

bit 4 When CAN is in Mode 0:

TXB2IP: CAN Transmit Buffer 2 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1 or 2:

TXBnIP: CAN Transmit Buffer Interrupt Priority bit

1 = High priority

0 = Low priority

bit 3 TXB1IP: CAN Transmit Buffer 1 Interrupt Priority bit(1)

1 = High priority

0 = Low priority

bit 2 TXB0IP: CAN Transmit Buffer 0 Interrupt Priority bit(1)

1 = High priority

0 = Low priority

bit 1 When CAN is in Mode 0:

RXB1IP: CAN Receive Buffer 1 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1 or 2:

RXBnIP: CAN Receive Buffer Interrupts Priority bit

1 = High priority

0 = Low priority

bit 0 When CAN is in Mode 0:

RXB0IP: CAN Receive Buffer 0 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIP: FIFO Watermark Interrupt Priority bit

1 = High priority

0 = Low priority

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

9.5 RCON Register

The RCON register contains flag bits which are used to

determine the cause of the last Reset or wake-up from

Idle or Sleep modes. RCON also contains the IPEN bit

which enables interrupt priorities.

R/W-0 U-0 U-0 R/W-1 R-1 R-1 R/W-0 R/W-0

IPEN SBOREN —RITO PD POR BOR

bit 7 bit 0

bit 7 IPEN: Interrupt Priority Enable bit

1 = Enable priority levels on interrupts

0 = Disable priority levels on interrupts (PIC16CXXX Compatibility mode)

bit 6 SBOREN: BOR Software Enable bit

For details of bit operation, see Register 4-1.

bit 5 Unimplemented: Read as ‘0’

bit 4 RI: RESET Instruction Flag bit

For details of bit operation, see Register 4-1.

bit 3 TO: Watchdog Time-out Flag bit

For details of bit operation, see Register 4-1.

bit 2 PD: Power-down Detection Flag bit

For details of bit operation, see Register 4-1.

bit 1 POR: Power-on Reset Status bit

For details of bit operation, see Register 4-1.

bit 0 BOR: Brown-out Reset Status bit

For details of bit operation, see Register 4-1.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

9.6 INTn Pin Interrupts

External interrupts on the RB0/INT0, RB1/INT1 and

RB2/INT2 pins are edge-triggered. If the corresponding

INTEDGx bit in the INTCON2 register is set (= 1), the

interrupt is triggered by a rising edge; if the bit is clear,

the trigger is on the falling edge. When a valid edge

appears on the RBx/INTx pin, the corresponding flag

bit INTxF is set. This interrupt can be disabled by clear-

ing the corresponding enable bit INTxE. Flag bit INTxF

must be cleared in software in the Interrupt Service

Routine before re-enabling the interrupt.

All external interrupts (INT0, INT1 and INT2) can

wake-up the processor from the power managed

modes, if bit INTxE was set prior to going into power

managed modes. If the Global Interrupt Enable bit,

GIE, is set, the processor will branch to the interrupt

vector following wake-up.

Interrupt priority for INT1 and INT2 is determined by the

value contained in the interrupt priority bits, INT1IP

(INTCON3<6>) and INT2IP (INTCON3<7>). There is

no priority bit associated with INT0. It is always a high

priority interrupt source.

9.7 TMR0 Interrupt

In 8-bit mode (which is the default), an overflow in the

TMR0 register (FFh →00h) will set flag bit TMR0IF. In

16-bit mode, an overflow in the TMR0H:TMR0L regis-

ter pair (FFFFh → 0000h) will set TMR0IF. The interrupt

can be enabled/disabled by setting/clearing enable bit

TMR0IE (INTCON<5>). Interrupt priority for Timer0 is

determined by the value contained in the interrupt

priority bit, TMR0IP (INTCON2<2>). See Section 11.0

“Timer0 Module” for further details on the Timer0

module.

9.8 PORTB Interrupt-on-Change

An input change on PORTB<7:4> sets flag bit, RBIF

(INTCON<0>). The interrupt can be enabled/disabled

by setting/clearing enable bit, RBIE (INTCON<3>).

Interrupt priority for PORTB interrupt-on-change is

determined by the value contained in the interrupt

priority bit, RBIP (INTCON2<0>).

9.9 Context Saving During Interrupts

During interrupts, the return PC address is saved on

the stack. Additionally, the WREG, STATUS and BSR

registers are saved on the fast return stack. If a fast

return from interrupt is not used (See Section 5.3

“Data Memory Organization”), the user may need to

save the WREG, STATUS and BSR registers on entry

to the Interrupt Service Routine. Depending on the

user’s application, other registers may also need to be

saved. Example 9-1 saves and restores the WREG,

STATUS and BSR registers during an Interrupt Service

Routine.

EXAMPLE 9-1: SAVING STATUS, WREG AND BSR REGISTERS IN RAM

MOVWF W_TEMP ; W_TEMP is in virtual bank

MOVFF STATUS, STATUS_TEMP ; STATUS_TEMP located anywhere

MOVFF BSR, BSR_TEMP ; BSR_TMEP located anywhere

;

; USER ISR CODE

;

MOVFF BSR_TEMP, BSR ; Restore BSR

MOVF W_TEMP, W ; Restore WREG

MOVFF STATUS_TEMP, STATUS ; Restore STATUS

PIC18F2585/2680/4585/4680

10.0 I/O PORTS

Depending on the device selected and features

enabled, there are up to five ports available. Some pins

of the I/O ports are multiplexed with an alternate

function from the peripheral features on the device. In

general, when a peripheral is enabled, that pin may not

be used as a general purpose I/O pin.

Each port has three registers for its operation. These

registers are:

• TRIS register (data direction register)

• PORT register (reads the levels on the pins of the

device)

• LAT register (output latch)

The Data Latch register (LAT) is useful for read-modify-

write operations on the value that the I/O pins are

driving.

A simplified model of a generic I/O port, without the

interfaces to other peripherals, is shown in Figure 10-1.

FIGURE 10-1: GENERIC I/O PORT

OPERATION

10.1 PORTA, TRISA and LATA Registers

PORTA is an 8-bit wide, bidirectional port. The

corresponding data direction register is TRISA. Setting

a TRISA bit (= 1) will make the corresponding PORTA

pin an input (i.e., put the corresponding output driver in

a high-impedance mode). Clearing a TRISA bit (= 0)

will make the corresponding PORTA pin an output (i.e.,

put the contents of the output latch on the selected pin).

Reading the PORTA register reads the status of the

pins, whereas writing to it, will write to the port latch.

The Data Latch register (LATA) is also memory

mapped. Read-modify-write operations on the LATA

PORTA.

The RA4 pin is multiplexed with the Timer0 module

clock input to become the RA4/T0CKI pin. Pins RA6

and RA7 are multiplexed with the main oscillator pins;

they are enabled as oscillator or I/O pins by the selec-

tion of the main oscillator in Configuration Register 1H

(see Section 24.1 “Configuration Bits” for details).

When they are not used as port pins, RA6 and RA7 and

their associated TRIS and LAT bits are read as ‘0’.

The other PORTA pins are multiplexed with analog

inputs, the analog VREF+ and VREF- inputs and the

comparator voltage reference output. The operation of

pins RA3:RA0 and RA5 as A/D converter inputs is

selected by clearing/setting the control bits in the

ADCON1 register (A/D Control Register 1).

All other PORTA pins have TTL input levels and full

CMOS output drivers.

The TRISA register controls the direction of the RA

pins, even when they are being used as analog inputs.

The user must ensure the bits in the TRISA register are

maintained set when using them as analog inputs.

EXAMPLE 10-1: INITIALIZING PORTA

Data

Bus

WR LAT

WR TRIS

RD Port

Data Latch

TRIS Latch

RD TRIS

Input

Buffer

I/O pin(1)

RD LAT

or Port

Note 1: I/O pins have diode protection to VDD and VSS.

Note: On a Power-on Reset, RA5 and RA3:RA0

are configured as analog inputs and read

as ‘0’. RA4 is configured as a digital input.

CLRF PORTA ; Initialize PORTA by

; clearing output

; data latches

CLRF LATA ; Alternate method

; to clear output

; data latches

MOVLW 0Fh ; Configure A/D

MOVWF ADCON1 ; for digital inputs

MOVWF 07h ; Configure comparators

MOVWF CMCON ; for digital input

MOVLW 0CFh ; Value used to

; initialize data

; direction

MOVWF TRISA ; Set RA<3:0> as inputs

; RA<5:4> as outputs

PIC18F2585/2680/4585/4680

TABLE 10-1: PORTA I/O SUMMARY

Pin Name Function I/O TRIS Buffer Description

RA0/AN0/CVREF RA0 OUT 0DIG LATA<0> data output.

IN 1TTL PORTA<0> data input.

AN0 IN 1ANA A/D input channel 0. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

CVREF OUT xANA Comparator voltage reference analog output. Enabling this analog

output overrides the digital I/O (read as clear – low level).

RA1/AN1 RA1 OUT 0DIG LATA<1> data output.

IN 1TTL PORTA<1> data input.

AN1 IN 1ANA A/D input channel 1. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

RA2/AN2/VREF-RA2 OUT0DIG LATA<2> data output.

IN 1TTL PORTA<2> data input.

AN2 IN 1ANA A/D input channel 2. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

VREF-IN1ANA A/D and comparator negative voltage analog input.

RA3/AN3/VREF+RA3 OUT0DIG LATA<3> data output.

IN 1TTL PORTA<3> data input.

AN3 IN 1ANA A/D input channel 3. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

VREF+IN1ANA A/D and comparator positive voltage analog input.

RA4/T0CKI RA4 OUT 0DIG LATA<4> data output.

IN 1TTL PORTA<4> data input.

T0CKI IN 1ST Timer0 clock input.

RA5/AN4/SS/HLVDIN RA5 OUT 0DIG LATA<5> data output.

IN 1TTL PORTA<5> data input.

AN4 IN 1ANA A/D input channel 4. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

SS IN 1TTL Slave select input for MSSP.

HLVDIN IN 1ANA High/Low-Voltage Detect external trip point input.

OSC2/CLKO/RA6 OSC2 OUT xANA Output connection, selected by FOSC3:FOSC0 Configuration bits.

Enabling OSC2 overrides digital I/O.

CLKO OUT xDIG Output connection, selected by FOSC3:FOSC0 Configuration bits.

Enabling CLKO overrides digital I/O (FOSC/4).

RA6 OUT 0DIG LATA<6> data output.

IN 1TTL PORTA<6> data input.

OSC1/CLKI/RA7 OSC1 IN xANA Main oscillator input connection, determined by FOSC3:FOSC0

Configuration bits. Enabling OSC1 overrides digital I/O.

CLKI IN xANA Main clock input connection, determined by FOSC3:FOSC0

Configuration bits. Enabling CLKI overrides digital I/O.

RA7 OUT 0DIG LATA<7> data output.

IN 1TTL PORTA<7> data input.

Legend: PWR = Power Supply; OUT = Output; IN = Input; ANA = Analog Signal; DIG = Digital Output; ST = Schmitt Buffer Input;

TTL = TTL Buffer Input

PIC18F2585/2680/4585/4680

TABLE 10-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

PORTA RA7(1) RA6(1) RA5 RA4 RA3 RA2 RA1 RA0 52

LATA LATA7(1) LATA6(1) LATA Data Output Register 52

TRISA TRISA7(1) TRISA6(1) PORTA Data Direction Register 52

ADCON1 — — VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 50

CMCON(2) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51

CVRCON(2) CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTA.

Note 1: RA7:RA6 and their associated latch and data direction bits are enabled as I/O pins based on oscillator

configuration; otherwise, they are read as ‘0’.

2: These registers are unimplemented on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

10.2 PORTB, TRISB and LATB

Registers

PORTB is an 8-bit wide, bidirectional port. The

corresponding data direction register is TRISB. Setting

a TRISB bit (= 1) will make the corresponding PORTB

pin an input (i.e., put the corresponding output driver in

a high-impedance mode). Clearing a TRISB bit (= 0)

will make the corresponding PORTB pin an output (i.e.,

put the contents of the output latch on the selected pin).

The Data Latch register (LATB) is also memory

mapped. Read-modify-write operations on the LATB

PORTB.

Pins RB2 through RB3 are multiplexed with the ECAN

peripheral. Refer to Section 23.0 “ECAN™ Technol-

ogy” for proper settings of TRISB when CAN is

enabled.

EXAMPLE 10-2: INITIALIZING PORTB

Each of the PORTB pins has a weak internal pull-up. A

single control bit can turn on all the pull-ups. This is

performed by clearing bit RBPU (INTCON2<7>). The

weak pull-up is automatically turned off when the port

pin is configured as an output. The pull-ups are

disabled on all device Resets.

Four of the PORTB pins (RB7:RB4) have an interrupt-

on-change feature. Only pins configured as inputs can

cause this interrupt to occur (i.e., any RB7:RB4 pin

configured as an output is excluded from the interrupt-

on-change comparison). The input pins (of RB7:RB4)

are compared with the old value latched on the last

read of PORTB. The “mismatch” outputs of RB7:RB4

are ORed together to generate the RB Port Change

Interrupt with Flag bit, RBIF (INTCON<0>).

This interrupt can wake the device from Sleep. The

user, in the Interrupt Service Routine, can clear the

interrupt in the following manner:

a) Any read or write of PORTB (except with the

MOVFF (ANY), PORTB instruction). This will

end the mismatch condition.

b) Clear flag bit RBIF.

A mismatch condition will continue to set flag bit RBIF.

Reading PORTB will end the mismatch condition and

allow flag bit RBIF to be cleared.

The interrupt-on-change feature is recommended for

wake-up on key depression operation and operations

where PORTB is only used for the interrupt-on-change

feature. Polling of PORTB is not recommended while

using the interrupt-on-change feature.

Note: On a Power-on Reset, RB4:RB0 are

configured as analog inputs by default and

read as ‘0’; RB7:RB5 are configured as

digital inputs.

By programming the Configuration bit,

PBADEN (CONFIG3H<1>), RB4:RB0 will

alternatively be configured as digital inputs

on POR.

CLRF PORTB ; Initialize PORTB by

; clearing output

; data latches

CLRF LATB ; Alternate method

; to clear output

; data latches

MOVLW 0Eh ; Set RB<4:0> as

MOVWF ADCON1 ; digital I/O pins

; (required if config bit

; PBADEN is set)

MOVLW 0CFh ; Value used to

; initialize data

; direction

MOVWF TRISB ; Set RB<3:0> as inputs

; RB<5:4> as outputs

; RB<7:6> as inputs

PIC18F2585/2680/4585/4680

TABLE 10-3: PORTB I/O SUMMARY

Pin Name Function I/O TRIS Buffer Description

RB0/INT0/FLT0/AN10 RB0 OUT 0DIG LATB<0> data output.

IN 1TTL PORTB<0> data input. Weak pull-up available only in this mode.

INT0 IN 1ST External interrupt 0 input.

FLT0 IN 1ST Enhanced PWM Fault input.

AN10 IN 1ANA A/D input channel 10. Enabled on POR, this analog input overrides

the digital input (read as clear – low level).

RB1/INT1/AN8 RB1 OUT 0DIG LATB<1> data output.

IN 1TTL PORTB<1> data input. Weak pull-up available only in this mode.

INT1 IN 1ST External interrupt 1 input.

AN8 IN 1ANA A/D input channel 8. Enabled on POR, this analog input overrides

the digital input (read as clear – low level).

RB2/INT2/CANTX RB2 OUT xDIG LATB<2> data output.

IN 1TTL PORTB<2> data input. Weak pull-up available only in this mode.

INT2 IN 1ST External interrupt 2 input.

CANTX OUT 1DIG CAN transmit signal output. The CAN interface overrides the

TRIS<2> control when enabled.

RB3/CANRX RB3 OUT 0DIG LATB<3> data output.

IN 1TTL PORTB<3> data input. Weak pull-up available only in this mode.

CANRX IN 1ST CAN receive signal input. Pin must be configured as a digital input by

setting TRISB<3>.

RB4/KBI0/AN9 RB4 OUT 0DIG LATB<4> data output.

IN 1TTL PORTB<4> data input. Weak pull-up available only in this mode.

KBI0 IN 1TTL Interrupt-on-pin change.

AN9 IN 1ANA A/D input channel 9. Enabled on POR, this analog input overrides

the digital input (read as clear – low level).

RB5/KBI1/PGM RB5 OUT 0DIG LATB<5> data output.

IN 1TTL PORTB<5> data input. Weak pull-up available only in this mode.

KBI1 IN 1TTL Interrupt-on-pin change.

PGM IN xST Low-Voltage Programming mode entry (ICSP™). Enabling this

function overrides digital output.

RB6/KBI2/PGC RB6 OUT 0DIG LATB<6> data output.

IN 1TTL PORTB<6> data input. Weak pull-up available only in this mode.

KBI2 IN 1TTL Interrupt-on-pin change.

PGC IN xST Low-Voltage Programming mode entry (ICSP) clock input.

RB7/KBI3/PGD RB7 OUT 0DIG LATB<7> data output.

IN 1TTL PORTB<7> data input. Weak pull-up available only in this mode.

KBI3 IN 1TTL Interrupt-on-pin change.

PGD OUT xDIG Low-Voltage Programming mode entry (ICSP) clock output.

IN xST Low-Voltage Programming mode entry (ICSP) clock input.

Legend: PWR = Power Supply; OUT = Output; IN = Input; ANA = Analog Signal; DIG = Digital Output; ST = Schmitt Buffer Input;

TTL – TTL Buffer Input

PIC18F2585/2680/4585/4680

TABLE 10-4: SUMMARY OF REGISTERS ASSOCIATED WITH PORTB

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 52

LATB LATB Data Output Register (Read and Write to Data Latch) 52

TRISB PORTB Data Direction Control Register 52

INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49

INTCON2 RBPU INTEDG0 INTEDG1 INTEDG2 —TMR0IP —RBIP49

INTCON3 INT2IP INT1IP —INT2IEINT1IE— INT2IF INT1IF 49

ADCON1 — — VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 50

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTB.

PIC18F2585/2680/4585/4680

10.3 PORTC, TRISC and LATC

Registers

PORTC is an 8-bit wide, bidirectional port. The

corresponding data direction register is TRISC. Setting

a TRISC bit (= 1) will make the corresponding PORTC

pin an input (i.e., put the corresponding output driver in

a high-impedance mode). Clearing a TRISC bit (= 0)

will make the corresponding PORTC pin an output (i.e.,

put the contents of the output latch on the selected pin).

The Data Latch register (LATC) is also memory

mapped. Read-modify-write operations on the LATC

PORTC.

PORTC is multiplexed with several peripheral functions

(Table 10-5). The pins have Schmitt Trigger input

buffers.

When enabling peripheral functions, care should be

taken in defining TRIS bits for each PORTC pin. Some

peripherals override the TRIS bit to make a pin an output,

while other peripherals override the TRIS bit to make a

pin an input. The user should refer to the corresponding

peripheral section for the correct TRIS bit settings.

The contents of the TRISC register are affected by

peripheral overrides. Reading TRISC always returns

the current contents, even though a peripheral device

may be overriding one or more of the pins.

EXAMPLE 10-3: INITIALIZING PORTC

Note: On a Power-on Reset, these pins are

configured as digital inputs.

CLRF PORTC ; Initialize PORTC by

; clearing output

; data latches

CLRF LATC ; Alternate method

; to clear output

; data latches

MOVLW 0CFh ; Value used to

; initialize data

; direction

MOVWF TRISC ; Set RC<3:0> as inputs

; RC<5:4> as outputs

; RC<7:6> as inputs

PIC18F2585/2680/4585/4680

TABLE 10-5: PORTC I/O SUMMARY

Pin Name Function I/O TRIS Buffer Description

RC0/T1OSO/

T13CKI

RC0 OUT 0DIG LATC<0> data output.

IN 1ST PORTC<0> data input.

T1OSO OUT xANA Timer1 oscillator output – overrides the TRIS<0> control when enabled.

T13CKI IN 1ST Timer1/Timer3 clock input.

RC1/T1OSI RC1 OUT 0DIG LATC<1> data output.

IN 1ST PORTC<1> data input.

T1OSI IN xANA Timer1 oscillator input – overrides the TRIS<1> control when enabled.

RC2/CCP1 RC2 OUT 0DIG LATC<2> data output.

IN 1ST PORTC<2> data input.

CCP1 OUT 0DIG CCP1 compare output.

IN 1ST CCP1 capture input.

RC3/SCK/SCL RC3 OUT 0DIG LATC<3> data output.

IN 1ST PORTC<3> data input.

SCK OUT 0DIG SPI clock output (MSSP module) – must have TRIS set to ‘1’ to allow the

MSSP module to control the bidirectional communication.

IN 1ST SPI clock input (MSSP module).

SCL OUT 0DIG I2C™/SM bus clock output (MSSP module) – must have TRIS set to ‘1’ to

allow the MSSP module to control the bidirectional communication.

IN 1I2C/SMB I2C/SM bus clock input.

RC4/SDI/SDA RC4 OUT 0DIG LATC<4> data output.

IN 1ST PORTC<4> data input.

SDI IN 1ST SPI data input (MSSP module).

SDA OUT 1DIG I2C/SM bus data output (MSSP module) – must have TRIS set to ‘1’ to

allow the MSSP module to control the bidirectional communication.

IN 1I2C/SMB I2C/SM bus data input (MSSP module) – must have TRIS set to ‘1’ to allow

the MSSP module to control the bidirectional communication.

RC5/SDO RC5 OUT 0DIG LATC<5> data output.

IN 1ST PORTC<5> data input.

SDO OUT 0DIG SPI data output (MSSP module).

RC6/TX/CK RC6 OUT 0DIG LATC<6> data output.

IN 1ST PORTC<6> data input.

TX OUT 0DIG EUSART data output.

CK OUT 1DIG EUSART synchronous clock output – must have TRIS set to ‘1’ to enable

EUSART to control the bidirectional communication.

IN 1ST EUSART synchronous clock input.

RC7/RX/DT RC7 OUT 0DIG LATC<7> data output.

IN 1ST PORTC<7> data input.

RX IN 1ST EUSART asynchronous data input.

DT OUT 1DIG EUSART synchronous data output – must have TRIS set to ‘1’ to enable

EUSART to control the bidirectional communication.

IN 1ST EUSART synchronous data input.

Legend: PWR = Power Supply; OUT = Output; IN = Input; ANA = Analog Signal; DIG = Digital Output; ST = Schmitt Buffer Input;

TTL = TTL Buffer Input

PIC18F2585/2680/4585/4680

TABLE 10-6: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 52

LATC PORTC Data Output Register 52

TRISC PORTC Data Direction Register 52

PIC18F2585/2680/4585/4680

10.4 PORTD, TRISD and LATD

Registers

PORTD is an 8-bit wide, bidirectional port. The corre-

sponding Data Direction register is TRISD. Setting a

TRISD bit (= 1) will make the corresponding PORTD

pin an input (i.e., put the corresponding output driver in

a high-impedance mode). Clearing a TRISD bit (= 0)

will make the corresponding PORTD pin an output (i.e.,

put the contents of the output latch on the selected pin).

The Data Latch register (LATD) is also memory

mapped. Read-modify-write operations on the LATD

PORTD.

All pins on PORTD are implemented with Schmitt Trigger

input buffers. Each pin is individually configurable as an

input or output.

Three of the PORTD pins are multiplexed with outputs

P1A, P1B, P1C and P1D of the Enhanced CCP1

(ECCP1) module. The operation of these additional

PWM output pins is covered in greater detail in

Section 16.0 “Enhanced Capture/Compare/PWM

(ECCP1) Module”.

PORTD can also be configured as an 8-bit wide micro-

processor port (Parallel Slave Port) by setting control

bit, PSPMODE (TRISE<4>). In this mode, the input

buffers are TTL. See Section 10.6 “Parallel Slave

Port” for additional information on the Parallel Slave

Port (PSP).

EXAMPLE 10-4: INITIALIZING PORTD

Note: PORTD is only available on PIC18F4X8X

devices.

Note: On a Power-on Reset, these pins are

configured as digital inputs.

Note: When the Enhanced PWM mode is used

with either dual or quad outputs, the PSP

functions of PORTD are automatically

disabled.

CLRF PORTD ; Initialize PORTD by

; clearing output

; data latches

CLRF LATD ; Alternate method

; to clear output

; data latches

MOVLW 0CFh ; Value used to

; initialize data

; direction

MOVWF TRISD ; Set RD<3:0> as inputs

; RD<5:4> as outputs

; RD<7:6> as inputs

PIC18F2585/2680/4585/4680

TABLE 10-7: PORTD I/O SUMMARY

Pin Name Function I/O TRIS Buffer Description

RD0/PSP0/

C1IN+

RD0 OUT 0DIG LATD<0> data output.

IN 1ST PORTD<0> data input.

PSP0 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<0> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<0> control when enabled).

C1IN+ IN 1ANA Comparator 1 positive input B. Default on POR. This analog input overrides the digital

input (read as clear – low level).

RD1/PSP1/

C1IN-

RD1 OUT 0DIG LATD<1> data output.

IN 1ST PORTD<1> data input.

PSP1 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<1> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<1> control when enabled).

C1IN- IN 1ANA Comparator 1 negative input. Default on POR. This analog input overrides the digital

input (read as clear – low level).

RD2/PSP2/

C2IN+

RD2 OUT 0DIG LATD<2> data output.

IN 1ST PORTD<2> data input.

PSP2 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<2> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<2> control when enabled).

C2IN+ IN 1ANA Comparator 2 positive input. Default on POR. This analog input overrides the digital

input (read as clear – low level).

RD3/PSP3/

C2IN-

RD3 OUT 0DIG LATD<3> data output.

IN 1ST PORTD<3> data input.

PSP3 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<3> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<3> control when enabled).

C2IN- IN 1ANA Comparator 2 negative input. Default input on POR. This analog input overrides the

digital input (read as clear – low level).

RD4/PSP4/

ECCP1/P1A

RD4 OUT 0DIG LATD<4> data output.

IN 1ST PORTD<4> data input.

PSP4 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<4> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<4> control when enabled).

ECCP1 OUT 0DIG ECCP1 compare output.

IN 1ST ECCP1 capture input.

P1A OUT 0DIG ECCP1 Enhanced PWM output, channel A.

RD5/PSP5/

P1B

RD5 OUT 0DIG LATD<5> data output.

IN 1ST PORTD<5> data input.

PSP5 OUT XDIG Parallel Slave Port (PSP) data output (overrides the TRIS<5> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<5> control when enabled).

P1B OUT 0DIG ECCP1 Enhanced PWM output, channel B.

RD6/PSP6/

P1C

RD6 OUT 0DIG LATD<6> data output.

IN 1ST PORTD<6> data input.

PSP6 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<6> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<6> control when enabled).

P1C OUT 0DIG ECCP1 Enhanced PWM output, channel C.

RD7/PSP7/

P1D

RD7 OUT 0DIG LATD<7> data output.

IN 1ST PORTD<7> data input.

PSP7 OUT xDIG Parallel Slave Port (PSP) data output (overrides the TRIS<7> control when enabled).

IN xTTL Parallel Slave Port (PSP) data input (overrides the TRIS<7> control when enabled).

P1D OUT 0DIG ECCP1 Enhanced PWM output, channel D.

Legend: PWR = Power Supply; OUT = Output; IN = Input; ANA = Analog Signal; DIG = Digital Output; ST = Schmitt Buffer Input;

TTL = TTL Buffer Input

PIC18F2585/2680/4585/4680

TABLE 10-8: SUMMARY OF REGISTERS ASSOCIATED WITH PORTD

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

PORTD(1) RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 52

LATD(1) LATD Data Output Register 52

TRISD(1) PORTD Data Direction Register 52

TRISE(1) IBF OBF IBOV PSPMODE —PORTE Data Direction bits 52

ECCP1CON(1) EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0 51

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTD.

Note 1: These registers are available on PIC18F4X8X devices only.

PIC18F2585/2680/4585/4680

10.5 PORTE, TRISE and LATE

Registers

Depending on the particular PIC18F2585/2680/4585/

4680 device selected, PORTE is implemented in two

different ways.

For PIC18F4X8X devices, PORTE is a 4-bit wide port.

Three pins (RE0/RD/AN5, RE1/WR/AN6/C1OUT and

RE2/CS/AN7/C2OUT) are individually configurable as

inputs or outputs. These pins have Schmitt Trigger

input buffers. When selected as an analog input, these

pins will read as ‘0’s.

The corresponding data direction register is TRISE.

Setting a TRISE bit (= 1) will make the corresponding

PORTE pin an input (i.e., put the corresponding output

driver in a high-impedance mode). Clearing a TRISE bit

(= 0) will make the corresponding PORTE pin an output

(i.e., put the contents of the output latch on the selected

pin).

TRISE controls the direction of the RE pins, even when

they are being used as analog inputs. The user must

make sure to keep the pins configured as inputs when

using them as analog inputs.

The upper four bits of the TRISE register also control

the operation of the Parallel Slave Port. Their operation

is explained in Register 10-1.

The Data Latch register (LATE) is also memory

mapped. Read-modify-write operations on the LATE

PORTE.

The fourth pin of PORTE (MCLR/VPP/RE3) is an input

only pin. Its operation is controlled by the MCLRE

Configuration bit. When selected as a port pin

(MCLRE = 0), it functions as a digital input only pin. As

such, it does not have TRIS or LAT bits associated with

its operation. Otherwise, it functions as the device’s

Master Clear input. In either configuration, RE3 also

functions as the programming voltage input during

programming.

EXAMPLE 10-5: INITIALIZING PORTE

10.5.1 PORTE IN 28-PIN DEVICES

For PIC18F2X8X devices, PORTE is only available

when Master Clear functionality is disabled

(MCLRE = 0). In these cases, PORTE is a single bit,

input only port comprised of RE3 only. The pin operates

as previously described.

Note: On a Power-on Reset, RE2:RE0 are

configured as analog inputs.

Note: On a Power-on Reset, RE3 is enabled as

a digital input only if Master Clear

functionality is disabled.

CLRF PORTE ; Initialize PORTE by

; clearing output

; data latches

CLRF LATE ; Alternate method

; to clear output

; data latches

MOVLW 0Ah ; Configure A/D

MOVWF ADCON1 ; for digital inputs

MOVLW 03h ; Value used to

; initialize data

; direction

MOVLW 07h ; Turn off

MOVWF CMCON ; comparators

MOVWF TRISC ; Set RE<0> as inputs

; RE<1> as outputs

; RE<2> as inputs

PIC18F2585/2680/4585/4680

R-0 R-0 R/W-0 R/W-0 U-0 R/W-1 R/W-1 R/W-1

IBF OBF IBOV PSPMODE — TRISE2 TRISE1 TRISE0

bit 7 bit 0

bit 7 IBF: Input Buffer Full Status bit

1 = A word has been received and waiting to be read by the CPU

0 = No word has been received

bit 6 OBF: Output Buffer Full Status bit

1 = The output buffer still holds a previously written word

0 = The output buffer has been read

bit 5 IBOV: Input Buffer Overflow Detect bit (in Microprocessor mode)

1 = A write occurred when a previously input word has not been read (must be cleared in software)

0 = No overflow occurred

bit 4 PSPMODE: Parallel Slave Port Mode Select bit

1 = Parallel Slave Port mode

0 = General Purpose I/O mode

bit 3 Unimplemented: Read as ‘0’

bit 2 TRISE2: RE2 Direction Control bit

1 = Input

0 = Output

bit 1 TRISE1: RE1 Direction Control bit

1 = Input

0 = Output

bit 0 TRISE0: RE0 Direction Control bit

1 = Input

0 = Output

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

TABLE 10-9: PORTE I/O SUMMARY

TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE

Pin Name Function I/O TRIS Buffer Description

RE0/RD/AN5 RE0 OUT 0DIG LATE<0> data output.

IN 1ST PORTE<0> data input.

RD IN 1TTL PSP read enable input.

AN5 IN 1ANA A/D input channel 5. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

RE1/WR/AN6/C1OUT RE1 OUT 0DIG LATE<1> data output.

IN 1ST PORTE<1> data input.

WR IN 1TTL PSP write enable input.

AN6 IN 1ANA A/D input channel 6. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

C1OUT OUT 0DIG Comparator 1 output.

RE2/CS/AN7/C2OUT RE2 OUT 0DIG LATE<2> data output.

IN 1ST PORTE<2> data input.

CS IN 1TTL PSP chip select input.

AN7 IN 1ANA A/D input channel 7. Enabled on POR, this analog input overrides the

digital input (read as clear – low level).

C2OUT OUT 0DIG Comparator 2 output.

MCLR/VPP/RE3 MCLR IN xST External Reset input. Disabled when MCLRE Configuration bit is ‘1’.

VPP IN xANA High-voltage detection; used by ICSP™ operation.

RE3 IN 1ST PORTE<3> data input. Disabled when MCLRE Configuration bit is ‘0’.

Legend: PWR = Power Supply; OUT = Output; IN = Input; ANA = Analog Signal; DIG = Digital Output; ST = Schmitt Buffer Input;

TTL = TTL Buffer Input

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

PORTE(3) — — — —RE3

(1,2) RE2 RE1 RE0 52

LATE(2) — — — — — LATE Data Output Register 52

TRISE(3) IBF OBF IBOV PSPMODE — TRISE2 TRISE1 TRISE0 52

ADCON1 —— VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 50

CMCON(3) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PORTE.

Note 1: Implemented only when Master Clear functionality is disabled (MCLRE Configuration bit = 0).

2: RE3 is the only PORTE bit implemented on both PIC18F2X8X and PIC18F4X8X devices. All other bits are

implemented only when PORTE is implemented (i.e., PIC18F4X8X devices).

3: These registers are unimplemented on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

10.6 Parallel Slave Port

In addition to its function as a general I/O port, PORTD

can also operate as an 8-bit wide Parallel Slave Port

(PSP) or microprocessor port. PSP operation is

controlled by the 4 upper bits of the TRISE register

(Register 10-1). Setting control bit, PSPMODE

(TRISE<4>), enables PSP operation, as long as the

Enhanced CCP1 (ECCP1) module is not operating in

dual output or quad output PWM mode. In Slave mode,

the port is asynchronously readable and writable by the

external world.

The PSP can directly interface to an 8-bit micro-

processor data bus. The external microprocessor can

read or write the PORTD latch as an 8-bit latch. Setting

the control bit PSPMODE enables the PORTE I/O pins

to become control inputs for the microprocessor port.

When set, port pin RE0 is the RD input, RE1 is the WR

input and RE2 is the CS (Chip Select) input. For this

functionality, the corresponding data direction bits of

the TRISE register (TRISE<2:0>) must be configured

as inputs (set). The A/D port configuration bits,

PFCG3:PFCG0 (ADCON1<3:0>), must also be set to

‘1010’.

A write to the PSP occurs when both the CS and WR

lines are first detected low and ends when either are

detected high. The PSPIF and IBF flag bits are both set

when the write ends.

A read from the PSP occurs when both the CS and RD

lines are first detected low. The data in PORTD is read

out and the OBF bit is set. If the user writes new data

to PORTD to set OBF, the data is immediately read out;

however, the OBF bit is not set.

When either the CS or RD lines are detected high, the

PORTD pins return to the input state and the PSPIF bit

is set. User applications should wait for PSPIF to be set

before servicing the PSP; when this happens, the IBF

and OBF bits can be polled and the appropriate action

taken.

The timing for the control signals in Write and Read

modes is shown in Figure 10-3 and Figure 10-4,

respectively.

FIGURE 10-2: PORTD AND PORTE

BLOCK DIAGRAM

(PARALLEL SLAVE PORT)

Note: The Parallel Slave Port is only available on

PIC18F4X8X devices.

Data Bus

WR LATD RDx pin

RD PORTD

One bit of PORTD

Set Interrupt Flag

PSPIF (PIR1<7>)

Read

Chip Select

Write

TTL

WR PORTD

RD LATD

Data Latch

Note: I/O pins have diode protection to VDD and VSS.

PORTE Pins

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 145
PIC18F2585/2680/4585/4680
FIGURE 10-3: PARALLEL SLAVE PORT WRITE WAVEFORMS         
FIGURE 10-4: PARALLEL SLAVE PORT READ WAVEFORMS         
TABLE 10-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT     
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
PORTD(1) RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 52
LATD(1) PORTD Data Latch Register (Read and Write to Data Latch) 52
TRISD(1) PORTD Data Direction Control Register 52
PORTE(1) — — — — RE3 RE2 RE1 RE0 52
LATE(1) — — — — — LATE Data Output bits 52
TRISE(1) IBF OBF IBOV PSPMODE — TRISE2 TRISE1 TRISE0 52
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(2) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(2) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(2) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
ADCON1 —— VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 50
CMCON(1) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Parallel Slave Port.
Note 1: These registers are available on PIC18F4X8X devices only.
2: These registers are unimplemented on PIC18F2X8X devices and read as ‘0’.
Q1 Q2 Q3 Q4
CS
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
WR
RD
IBF
OBF
PSPIF
PORTD<7:0>
Q1 Q2 Q3 Q4
CS
Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
WR
IBF
PSPIF
RD
OBF
PORTD<7:0>

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

11.0 TIMER0 MODULE

The Timer0 module incorporates the following features:

• Software selectable operation as a timer or

counter in both 8-bit or 16-bit modes

• Readable and writable registers

• Dedicated 8-bit, software programmable

prescaler

• Selectable clock source (internal or external)

• Edge select for external clock

• Interrupt-on-overflow

The T0CON register (Register 11-1) controls all

aspects of the module’s operation, including the

prescale selection. It is both readable and writable.

A simplified block diagram of the Timer0 module in 8-bit

mode is shown in Figure 11-1. Figure 11-2 shows a

simplified block diagram of the Timer0 module in 16-bit

mode.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

TMR0ON T08BIT T0CS T0SE PSA T0PS2 T0PS1 T0PS0

bit 7 bit 0

bit 7 TMR0ON: Timer0 On/Off Control bit

1 = Enables Timer0

0 = Stops Timer0

bit 6 T08BIT: Timer0 8-bit/16-bit Control bit

1 = Timer0 is configured as an 8-bit timer/counter

0 = Timer0 is configured as a 16-bit timer/counter

bit 5 T0CS: Timer0 Clock Source Select bit

1 = Transition on T0CKI pin

0 = Internal instruction cycle clock (CLKO)

bit 4 T0SE: Timer0 Source Edge Select bit

1 = Increment on high-to-low transition on T0CKI pin

0 = Increment on low-to-high transition on T0CKI pin

bit 3 PSA: Timer0 Prescaler Assignment bit

1 = TImer0 prescaler is NOT assigned. Timer0 clock input bypasses prescaler.

0 = Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output.

bit 2-0 T0PS2:T0PS0: Timer0 Prescaler Select bits

111 = 1:256 Prescale value

110 = 1:128 Prescale value

101 = 1:64 Prescale value

100 = 1:32 Prescale value

011 = 1:16 Prescale value

010 = 1:8 Prescale value

001 = 1:4 Prescale value

000 = 1:2 Prescale value

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

11.1 Timer0 Operation

Timer0 can operate as either a timer or a counter; the

mode is selected by clearing the T0CS bit

(T0CON<5>). In Timer mode, the module increments

on every clock by default unless a different prescaler

value is selected (see Section 11.3 “Prescaler”). If

the TMR0 register is written to, the increment is inhib-

ited for the following two instruction cycles. The user

can work around this by writing an adjusted value to the

TMR0 register.

The Counter mode is selected by setting the T0CS bit

(= 1). In Counter mode, Timer0 increments either on

every rising or falling edge of pin RA4/T0CKI. The

incrementing edge is determined by the Timer0 Source

Edge Select bit, T0SE (T0CON<4>). Clearing this bit

selects the rising edge. Restrictions on the external

clock input are discussed below.

An external clock source can be used to drive Timer0;

however, it must meet certain requirements to ensure

that the external clock can be synchronized with the

internal phase clock (T

OSC). There is a delay between

synchronization and the onset of incrementing the

timer/counter.

11.2 Timer0 Reads and Writes in

16-Bit Mode

TMR0H is not the actual high byte of Timer0 in 16-bit

mode; it is actually a buffered version of the real high

byte of Timer0, which is not directly readable nor writ-

able (refer to Figure 11-2). TMR0H is updated with the

contents of the high byte of Timer0 during a read of

TMR0L. This provides the ability to read all 16 bits of

Timer0 without having to verify that the read of the high

and low byte were valid, due to a rollover between

successive reads of the high and low byte.

Similarly, a write to the high byte of Timer0 must also

take place through the TMR0H Buffer register. The high

byte is updated with the contents of TMR0H when a

write occurs to TMR0L. This allows all 16 bits of Timer0

to be updated at once.

FIGURE 11-1: TIMER0 BLOCK DIAGRAM (8-BIT MODE)

FIGURE 11-2: TIMER0 BLOCK DIAGRAM (16-BIT MODE)

Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.

T0CKI pin

T0SE

T0CS

FOSC/4

Programmable

Prescaler

Sync with

Internal

Clocks

TMR0L

(2 TCY Delay)

Internal Data Bus

PSA

T0PS2:T0PS0

Set

TMR0IF

on Overflow

Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale.

T0CKI pin

T0SE

T0CS

FOSC/4

Programmable

Prescaler

Sync with

Internal

Clocks TMR0L

(2 TCY Delay)

Internal Data Bus

PSA

T0PS2:T0PS0

Set

TMR0IF

on Overflow

TMR0

TMR0H

High Byte

Read TMR0L

Write TMR0L

PIC18F2585/2680/4585/4680

11.3 Prescaler

An 8-bit counter is available as a prescaler for the Timer0

module. The prescaler is not directly readable or writable;

its value is set by the PSA and T0PS2:T0PS0 bits

(T0CON<3:0>) which determine the prescaler

assignment and prescale ratio.

Clearing the PSA bit assigns the prescaler to the

Timer0 module. When it is assigned, prescale values

from 1:2 through 1:256 in power-of-2 increments are

selectable.

When assigned to the Timer0 module, all instructions

writing to the TMR0 register (e.g., CLRF TMR0, MOVWF

TMR0, BSF TMR0, etc.) clear the prescaler count.

11.3.1 SWITCHING PRESCALER

ASSIGNMENT

The prescaler assignment is fully under software

control and can be changed “on-the-fly” during program

execution.

11.4 Timer0 Interrupt

The TMR0 interrupt is generated when the TMR0

from FFFFh to 0000h in 16-bit mode. This overflow sets

the TMR0IF flag bit. The interrupt can be masked by

clearing the TMR0IE bit (INTCON<5>). Before re-

enabling the interrupt, the TMR0IF bit must be cleared

in software by the Interrupt Service Routine.

Since Timer0 is shut down in Sleep mode, the TMR0

interrupt cannot awaken the processor from Sleep.

TABLE 11-1: REGISTERS ASSOCIATED WITH TIMER0

Note: Writing to TMR0 when the prescaler is

assigned to Timer0 will clear the prescaler

count but will not change the prescaler

assignment.

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

TMR0L Timer0 Module Low Byte Register 50

TMR0H Timer0 Module High Byte Register 50

INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49

T0CON TMR0ON T08BIT T0CS T0SE PSA T0PS2 T0PS1 T0PS0 50

TRISA — PORTA Data Direction Register 52

Legend: x = unknown, u = unchanged, — = unimplemented locations, read as ‘0’.

Shaded cells are not used by Timer0.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

12.0 TIMER1 MODULE

The Timer1 timer/counter module incorporates these

features:

• Software selectable operation as a 16-bit timer or

counter

• Readable and writable 8-bit registers (TMR3H

and TMR3L)

• Selectable clock source (internal or external) with

device clock or Timer1 oscillator internal options

• Interrupt-on-overflow

• Module Reset on CCP1 special event trigger

• Device clock status flag (T1RUN)

A simplified block diagram of the Timer1 module is

shown in Figure 12-1. A block diagram of the module’s

operation in Read/Write mode is shown in Figure 12-2.

The module incorporates its own low-power oscillator

to provide an additional clocking option. The Timer1

oscillator can also be used as a low-power clock source

for the microcontroller in power managed operation.

Timer1 can also be used to provide Real-Time Clock

(RTC) functionality to applications with only a minimal

addition of external components and code overhead.

Timer1 is controlled through the T1CON Control

Oscillator Enable bit (T1OSCEN). Timer1 can be

enabled or disabled by setting or clearing control bit,

TMR1ON (T1CON<0>).

R/W-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON

bit 7 bit 0

bit 7 RD16: 16-bit Read/Write Mode Enable bit

1 = Enables register read/write of TImer1 in one 16-bit operation

0 = Enables register read/write of Timer1 in two 8-bit operations

bit 6 T1RUN: Timer1 System Clock Status bit

1 = Device clock is derived from Timer1 oscillator

0 = Device clock is derived from another source

bit 5-4 T1CKPS1:T1CKPS0: Timer1 Input Clock Prescale Select bits

11 = 1:8 Prescale value

10 = 1:4 Prescale value

01 = 1:2 Prescale value

00 = 1:1 Prescale value

bit 3 T1OSCEN: Timer1 Oscillator Enable bit

1 = Timer1 oscillator is enabled

0 = Timer1 oscillator is shut off

The oscillator inverter and feedback resistor are turned off to eliminate power drain.

bit 2 T1SYNC: Timer1 External Clock Input Synchronization Select bit

When TMR1CS = 1:

1 = Do not synchronize external clock input

0 = Synchronize external clock input

When TMR1CS = 0:

This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0.

bit 1 TMR1CS: Timer1 Clock Source Select bit

1 = External clock from pin RC0/T1OSO/T13CKI (on the rising edge)

0 = Internal clock (FOSC/4)

bit 0 TMR1ON: Timer1 On bit

1 = Enables Timer1

0 = Stops Timer1

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

12.1 Timer1 Operation

Timer1 can operate in one of these modes:

•Timer

• Synchronous Counter

• Asynchronous Counter

The operating mode is determined by the clock select

bit, TMR3CS (T3CON<1>). When TMR3CS is cleared

(= 0), Timer3 increments on every internal instruction

cycle (Fosc/4). When the bit is set, Timer3 increments

on every rising edge of the Timer1 external clock input

or the Timer1 oscillator, if enabled.

When Timer1 is enabled, the RC1/T1OSI and RC0/

T1OSO/T13CKI pins become inputs. This means the

values of TRISC<1:0> are ignored and the pins are

read as ‘0’.

FIGURE 12-1: TIMER1 BLOCK DIAGRAM

FIGURE 12-2: TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)

T1SYNC

TMR1CS

T1CKPS1:T1CKPS0

Sleep Input

T1OSCEN(1)

FOSC/4

Internal

Clock

On/Off

Prescaler

1, 2, 4, 8

Synchronize

Detect

T1OSO/T13CKI

T1OSI

TMR1ON

TMR1L Set

TMR1IF

on Overflow

TMR1

High Byte

Clear TMR1

(CCP1 Special Event Trigger)

Timer1 Oscillator

Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off to eliminate power drain.

On/Off

Timer1

T1SYNC

TMR1CS

T1CKPS1:T1CKPS0

Sleep Input

T1OSCEN(1)

FOSC/4

Internal

Clock

Prescaler

1, 2, 4, 8

Synchronize

Detect

T1OSO/T13CKI

T1OSI

Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off to eliminate power drain.

TMR1L

Internal Data Bus

Set

TMR1IF

on Overflow

TMR1

TMR1H

High Byte

Read TMR1L

Write TMR1L

TMR1ON

Clear TMR1

(CCP1 Special Event Trigger)

Timer1 Oscillator

On/Off

Timer1

PIC18F2585/2680/4585/4680

12.2 Timer1 16-Bit Read/Write Mode

Timer1 can be configured for 16-bit reads and writes

(see Figure 12-2). When the RD16 control bit

(T1CON<7>) is set, the address for TMR1H is mapped

to a buffer register for the high byte of Timer1. A read

from TMR1L will load the contents of the high byte of

Timer1 into the Timer1 High Byte Buffer register. This

provides the user with the ability to accurately read all

16 bits of Timer1 without having to determine whether

a read of the high byte, followed by a read of the low

byte, has become invalid due to a rollover between

reads.

A write to the high byte of Timer1 must also take place

through the TMR1H Buffer register. The Timer1 high

byte is updated with the contents of TMR1H when a

write occurs to TMR1L. This allows a user to write all

16 bits to both the high and low bytes of Timer1 at once.

The high byte of Timer1 is not directly readable or

writable in this mode. All reads and writes must take

place through the Timer1 High Byte Buffer register.

Writes to TMR1H do not clear the Timer1 prescaler.

The prescaler is only cleared on writes to TMR1L.

12.3 Timer1 Oscillator

An on-chip crystal oscillator circuit is incorporated

between pins T1OSI (input) and T1OSO (amplifier

output). It is enabled by setting the Timer1 Oscillator

Enable bit, T1OSCEN (T1CON<3>). The oscillator is a

low-power circuit rated for 32 kHz crystals. It will

continue to run during all power managed modes. The

circuit for a typical LP oscillator is shown in Figure 12-3.

Table 12-1 shows the capacitor selection for the Timer1

oscillator.

The user must provide a software time delay to ensure

proper start-up of the Timer1 oscillator.

FIGURE 12-3: EXTERNAL

COMPONENTS FOR THE

TIMER1 LP OSCILLATOR

TABLE 12-1: CAPACITOR SELECTION

FOR THE TIMER

OSCILLATOR(1,2,3,4)

12.3.1 USING TIMER1 AS A CLOCK

SOURCE

The Timer1 oscillator is also available as a clock source

in power managed modes. By setting the clock select

bits, SCS1:SCS0 (OSCCON<1:0>), to ‘01’, the device

switches to SEC_RUN mode; both the CPU and

peripherals are clocked from the Timer1 oscillator. If the

IDLEN bit (OSCCON<7>) is cleared and a SLEEP

instruction is executed, the device enters SEC_IDLE

mode. Additional details are available in Section 3.0

“Power Managed Modes”.

Whenever the Timer1 oscillator is providing the clock

source, the Timer1 system clock status flag, T1RUN

(T1CON<6>), is set. This can be used to determine the

controller’s current clocking mode. It can also indicate

the clock source being currently used by the Fail-Safe

Clock Monitor. If the Clock Monitor is enabled and the

Timer1 oscillator fails while providing the clock, polling

the T1RUN bit will indicate whether the clock is being

provided by the Timer1 oscillator or another source.

12.3.2 LOW-POWER TIMER1 OPTION

The Timer1 oscillator can operate at two distinct levels

of power consumption based on device configuration.

When the LPT1OSC Configuration bit is set, the Timer1

oscillator operates in a low-power mode. When

LPT1OSC is not set, Timer1 operates at a higher power

level. Power consumption for a particular mode is rela-

tively constant, regardless of the device’s operating

mode. The default Timer1 configuration is the higher

power mode.

As the low-power Timer1 mode tends to be more

sensitive to interference, high noise environments may

cause some oscillator instability. The low-power option is,

therefore, best suited for low noise applications where

power conservation is an important design consideration.

Note: See the Notes with Table 12-1 for additional

information about capacitor selection.

XTAL

PIC18FXXXX

T1OSI

T1OSO

32.768 kHz

33 pF

Osc Type Freq C1 C2

LP 32 kHz 27 pF 27 pF

Note 1: Microchip suggests these values as a

starting point in validating the oscillator

circuit.

2: Higher capacitance increases the stability

of the oscillator but also increases the

start-up time.

3: Since each resonator/crystal has its own

characteristics, the user should consult

the resonator/crystal manufacturer for

appropriate values of external

components.

4: Capacitor values are for design guidance

only.

PIC18F2585/2680/4585/4680

12.3.3 TIMER1 OSCILLATOR LAYOUT

CONSIDERATIONS

The Timer1 oscillator circuit draws very little power

during operation. Due to the low-power nature of the

oscillator, it may also be sensitive to rapidly changing

signals in close proximity.

The oscillator circuit, shown in Figure 12-3, should be

located as close as possible to the microcontroller.

There should be no circuits passing within the oscillator

circuit boundaries other than VSS or VDD.

If a high-speed circuit must be located near the oscilla-

tor (such as the CCP1 pin in Output Compare or PWM

mode, or the primary oscillator using the OSC2 pin), a

grounded guard ring around the oscillator circuit, as

shown in Figure 12-4, may be helpful when used on a

single-sided PCB or in addition to a ground plane.

FIGURE 12-4: OSCILLATOR CIRCUIT

WITH GROUNDED

GUARD RING

12.4 Timer1 Interrupt

The TMR1 register pair (TMR1H:TMR1L) increments

from 0000h to FFFFh and rolls over to 0000h. The

Timer1 interrupt, if enabled, is generated on overflow,

which is latched in interrupt flag bit, TMR1IF

(PIR1<0>). This interrupt can be enabled or disabled

by setting or clearing the Timer1 Interrupt Enable bit,

TMR1IE (PIE1<0>).

12.5 Resetting Timer1 Using the CCP1

Special Event Trigger

If either of the CCP1 modules is configured in Compare

mode to generate a special event trigger

(CCP1M3:CCP1M0 or CCP2M3:CCP2M0 = 1011),

this signal will reset Timer1. The trigger from ECCP1

will also start an A/D conversion if the A/D module is

enabled (see Section 15.3.4 “Special Event Trigger”

for more information.).

The module must be configured as either a timer or a

synchronous counter to take advantage of this feature.

When used this way, the CCPR1H:CCPR1L register

pair effectively becomes a period register for Timer1.

If Timer1 is running in Asynchronous Counter mode,

this Reset operation may not work.

In the event that a write to Timer1 coincides with a

special event trigger, the write operation will take

precedence.

12.6 Using Timer1 as a Real-Time

Clock

Adding an external LP oscillator to Timer1 (such as the

one described in Section 12.3 “Timer1 Oscillator”

above) gives users the option to include RTC function-

ality to their applications. This is accomplished with an

inexpensive watch crystal to provide an accurate time

base and several lines of application code to calculate

the time. When operating in Sleep mode and using a

battery or supercapacitor as a power source, it can

completely eliminate the need for a separate RTC

device and battery backup.

The application code routine, RTCisr, shown in

Example 12-1, demonstrates a simple method to

increment a counter at one-second intervals using an

Interrupt Service Routine. Incrementing the TMR1

the routine, which increments the seconds counter by

one; additional counters for minutes and hours are

incremented as the previous counter overflow.

Since the register pair is 16 bits wide, counting up to

overflow the register directly from a 32.768 kHz clock

would take 2 seconds. To force the overflow at the

required one-second intervals, it is necessary to pre-

load it. The simplest method is to set the MSb of

TMR1H with a BSF instruction. Note that the TMR1L

introduce cumulative error over many cycles.

For this method to be accurate, Timer1 must operate in

Asynchronous mode and the Timer1 overflow interrupt

must be enabled (PIE1<0> = 1) as shown in the routine,

RTCinit. The Timer1 oscillator must also be enabled

and running at all times.

VDD

OSC1

VSS

OSC2

RC0

RC1

RC2

Note: Not drawn to scale.

Note: The special event triggers from the

ECCP1 module will not set the TMR1IF

interrupt flag bit (PIR1<0>).

PIC18F2585/2680/4585/4680

EXAMPLE 12-1: IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE

TABLE 12-2: REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER

RTCinit

MOVLW 80h ; Preload TMR1 register pair

MOVWF TMR1H ; for 1 second overflow

CLRF TMR1L

MOVLW b’00001111’ ; Configure for external clock,

MOVWF T1OSC ; Asynchronous operation, external oscillator

CLRF secs ; Initialize timekeeping registers

CLRF mins ;

MOVLW .12

MOVWF hours

BSF PIE1, TMR1IE ; Enable Timer1 interrupt

RETURN

RTCisr

BSF TMR1H, 7 ; Preload for 1 sec overflow

BCF PIR1, TMR1IF ; Clear interrupt flag

INCF secs, F ; Increment seconds

MOVLW .59 ; 60 seconds elapsed?

CPFSGT secs

RETURN ; No, done

CLRF secs ; Clear seconds

INCF mins, F ; Increment minutes

MOVLW .59 ; 60 minutes elapsed?

CPFSGT mins

RETURN ; No, done

CLRF mins ; clear minutes

INCF hours, F ; Increment hours

MOVLW .23 ; 24 hours elapsed?

CPFSGT hours

RETURN ; No, done

MOVLW .01 ; Reset hours to 1

MOVWF hours

RETURN ; Done

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49

PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52

PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52

IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52

TMR1L Timer1 Register, Low Byte 50

TMR1H TImer1 Register, High Byte 50

T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50

Legend: x = unknown, u = unchanged, — = unimplemented, read as ‘0’.

Shaded cells are not used by the Timer1 module.

Note 1: These bits are unimplemented on PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

13.0 TIMER2 MODULE

The Timer2 module timer incorporates the following

features:

• 8-bit timer and period registers (TMR2 and PR2,

respectively)

• Readable and writable (both registers)

• Software programmable prescaler (1:1, 1:4 and

1:16)

• Software programmable postscaler (1:1 through

1:16)

• Interrupt on TMR2-to-PR2 match

• Optional use as the shift clock for the MSSP

module

The module is controlled through the T2CON register

(Register 13-1), which enables or disables the timer

and configures the prescaler and postscaler. Timer2

can be shut off by clearing control bit, TMR2ON

(T2CON<2>), to minimize power consumption.

A simplified block diagram of the module is shown in

Figure 13-1.

13.1 Timer2 Operation

In normal operation, TMR2 is incremented from 00h on

each clock (FOSC/4). A 2-bit counter/prescaler on the

clock input gives direct input, divide-by-4 and divide-by-

16 prescale options; these are selected by the prescaler

control bits, T2CKPS1:T2CKPS0 (T2CON<1:0>). The

value of TMR2 is compared to that of the period register,

PR2, on each clock cycle. When the two values match,

the comparator generates a match signal as the timer

output. This signal also resets the value of TMR2 to 00h

on the next cycle and drives the output counter/

postscaler (see Section 13.2 “Timer2 Interrupt”).

The TMR2 and PR2 registers are both directly readable

and writable. The TMR2 register is cleared on any

device Reset, while the PR2 register initializes at FFh.

Both the prescaler and postscaler counters are cleared

on the following events:

• a write to the TMR2 register

• a write to the T2CON register

• any device Reset (Power-on Reset, MCLR Reset,

Watchdog Timer Reset or Brown-out Reset)

TMR2 is not cleared when T2CON is written.

U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6-3 T2OUTPS3:T2OUTPS0: Timer2 Output Postscale Select bits

0000 = 1:1 Postscale

0001 = 1:2 Postscale

•

1111 = 1:16 Postscale

bit 2 TMR2ON: Timer2 On bit

1 = Timer2 is on

0 = Timer2 is off

bit 1-0 T2CKPS1:T2CKPS0: Timer2 Clock Prescale Select bits

00 = Prescaler is 1

01 = Prescaler is 4

1x = Prescaler is 16

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680
DS39625C-page 158 Preliminary © 2007 Microchip Technology Inc.
13.2 Timer2 Interrupt
Timer2 also can generate an optional device interrupt.
The Timer2 output signal (TMR2-to-PR2 match)
provides the input for the 4-bit output counter/
postscaler. This counter generates the TMR2 match
interrupt flag which is latched in TMR2IF (PIR1<1>).
The interrupt is enabled by setting the TMR2 Match
Interrupt Enable bit, TMR2IE (PIE1<1>).
A range of 16 postscale options (from 1:1 through 1:16
inclusive) can be selected with the postscaler control
bits, T2OUTPS3:T2OUTPS0 (T2CON<6:3>).
13.3 TMR2 Output
The unscaled output of TMR2 is available primarily to
the CCP1 modules, where it is used as a time base for
operations in PWM mode. 
Timer2 can be optionally used as the shift clock source
for the MSSP module operating in SPI mode.
Additional information is provided in Section 17.0
“Master Synchronous Serial Port (MSSP) Module”.
FIGURE 13-1: TIMER2 BLOCK DIAGRAM       
TABLE 13-1: REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER      
Comparator
TMR2 Output
TMR2
Postscaler
Prescaler PR2
2
FOSC/4
1:1 to 1:16
1:1, 1:4, 1:16
4
T2OUTPS3:T2OUTPS0
T2CKPS1:T2CKPS0
Set TMR2IF
Internal Data Bus
8
Reset
TMR2/PR2
8
8
(to PWM or MSSP) 
Match
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
TMR2 Timer2 Register 50
T2CON — T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 50
PR2 Timer2 Period Register 50
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module.
Note 1: These bits are unimplemented on PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

14.0 TIMER3 MODULE

The Timer3 module timer/counter incorporates these

features:

• Software selectable operation as a 16-bit timer or

counter

• Readable and writable 8-bit registers (TMR3H

and TMR3L)

• Selectable clock source (internal or external) with

device clock or Timer1 oscillator internal options

• Interrupt-on-overflow

• Module Reset on CCP1 special event trigger

A simplified block diagram of the Timer3 module is

shown in Figure 14-1. A block diagram of the module’s

operation in Read/Write mode is shown in Figure 14-2.

The Timer3 module is controlled through the T3CON

options for the CCP1 modules (see Section 15.1.1

“CCP1 Modules and Timer Resources” for more

information).

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

RD16 T3ECCP1(1) T3CKPS1 T3CKPS0 T3CCP1(1) T3SYNC TMR3CS TMR3ON

bit 7 bit 0

bit 7 RD16: 16-bit Read/Write Mode Enable bit

1 = Enables register read/write of Timer3 in one 16-bit operation

0 = Enables register read/write of Timer3 in two 8-bit operations

bit 6,3 T3ECCP1:T3CCP1: Timer3 and Timer1 to ECCP1/CCP1 Enable bits(1)

1x = Timer3 is the capture/compare clock source for both CCP1 and ECCP1 modules

01 = Timer3 is the capture/compare clock source for ECCP1;

Timer1 is the capture/compare clock source for CCP1

00 = Timer1 is the capture/compare clock source for both CCP1 and ECCP1 modules

Note 1: These bits are available on PIC18F4X8X devices only.

bit 5-4 T3CKPS1:T3CKPS0: Timer3 Input Clock Prescale Select bits

11 = 1:8 Prescale value

10 = 1:4 Prescale value

01 = 1:2 Prescale value

00 = 1:1 Prescale value

bit 2 T3SYNC: Timer3 External Clock Input Synchronization Control bit

(Not usable if the device clock comes from Timer1/Timer3.)

When TMR3CS = 1:

1 = Do not synchronize external clock input

0 = Synchronize external clock input

When TMR3CS = 0:

This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0.

bit 1 TMR3CS: Timer3 Clock Source Select bit

1 = External clock input from Timer1 oscillator or T13CKI (on the rising edge after the first

falling edge)

0 = Internal clock (FOSC/4)

bit 0 TMR3ON: Timer3 On bit

1 = Enables Timer3

0 = Stops Timer3

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

14.1 Timer3 Operation

Timer3 can operate in one of three modes:

•Timer

• Synchronous Counter

• Asynchronous Counter

The operating mode is determined by the clock select

bit, TMR3CS (T3CON<1>). When TMR3CS is cleared

(= 0), Timer3 increments on every internal instruction

cycle (FOSC/4). When the bit is set, Timer3 increments

on every rising edge of the Timer1 external clock input

or the Timer1 oscillator if enabled.

As with Timer1, the RC1/T1OSI and RC0/T1OSO/

T13CKI pins become inputs when the Timer1 oscillator

is enabled. This means the values of TRISC<1:0> are

ignored and the pins are read as ‘0’.

FIGURE 14-1: TIMER3 BLOCK DIAGRAM

FIGURE 14-2: TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE)

T3SYNC

TMR3CS

T3CKPS1:T3CKPS0

Sleep Input

T1OSCEN(1)

FOSC/4

Internal

Clock

Prescaler

1, 2, 4, 8

Synchronize

Detect

T1OSO/T13CKI

T1OSI

TMR3ON

TMR3L Set

TMR3IF

on Overflow

TMR3

High Byte

Timer1 Oscillator

Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off to eliminate power drain.

On/Off

Timer3

CCP1/ECCP1 Special Event Trigger

TCCPx

Clear TMR3

T3SYNC

TMR3CS

T3CKPS1:T3CKPS0

Sleep Input

T1OSCEN(1)

FOSC/4

Internal

Clock

Prescaler

1, 2, 4, 8

Synchronize

Detect

T1OSO/T13CKI

T1OSI

Note 1: When enable bit T1OSCEN is cleared, the inverter and feedback resistor are turned off to eliminate power drain.

TMR3L

Internal Data Bus

Set

TMR3IF

on Overflow

TMR3

TMR3H

High Byte

Read TMR1L

Write TMR1L

TMR3ON

CCP1/ECCP1 Special Event Trigger

Timer1 Oscillator

On/Off

Timer3

Timer1 clock input

TCCPx

Clear TMR3

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 161
PIC18F2585/2680/4585/4680
14.2 Timer3 16-Bit Read/Write Mode
Timer3 can be configured for 16-bit reads and writes
(see Figure 14-2). When the RD16 control bit
(T3CON<7>) is set, the address for TMR3H is mapped
to a buffer register for the high byte of Timer3. A read
from TMR3L will load the contents of the high byte of
Timer3 into the Timer3 High Byte Buffer register. This
provides the user with the ability to accurately read all
16 bits of Timer1 without having to determine whether
a read of the high byte, followed by a read of the low
byte, has become invalid due to a rollover between
reads.
A write to the high byte of Timer3 must also take place
through the TMR3H Buffer register. The Timer3 high
byte is updated with the contents of TMR3H when a
write occurs to TMR3L. This allows a user to write all
16 bits to both the high and low bytes of Timer3 at once.
The high byte of Timer3 is not directly readable or
writable in this mode. All reads and writes must take
place through the Timer3 High Byte Buffer register. 
Writes to TMR3H do not clear the Timer3 prescaler.
The prescaler is only cleared on writes to TMR3L.
14.3 Using the Timer1 Oscillator as the 
Timer3 Clock Source
The Timer1 internal oscillator may be used as the clock
source for Timer3. The Timer1 oscillator is enabled by
setting the T1OSCEN (T1CON<3>) bit. To use it as the
Timer3 clock source, the TMR3CS bit must also be set.
As previously noted, this also configures Timer3 to
increment on every rising edge of the oscillator source.
The Timer1 oscillator is described in Section 12.0
“Timer1 Module”.
14.4 Timer3 Interrupt
The TMR3 register pair (TMR3H:TMR3L) increments
from 0000h to FFFFh and overflows to 0000h. The
Timer3 interrupt, if enabled, is generated on overflow
and is latched in the interrupt flag bit, TMR3IF
(PIR2<1>). This interrupt can be enabled or disabled
by setting or clearing the Timer3 Interrupt Enable bit,
TMR3IE (PIE2<1>).
14.5 Resetting Timer3 Using the 
ECCP1 Special Event Trigger
If the ECCP1 module is configured to generate a
special event trigger in Compare mode
(ECCP1M3:ECCP1M0 = 1011), this signal will reset
Timer3. It will also start an A/D conversion if the A/D
module is enabled (see Section 15.3.4 “Special
Event Trigger” for more information.). 
The module must be configured as either a timer or
synchronous counter to take advantage of this feature.
When used this way, the ECCPR1H:ECCPR1L register
pair effectively becomes a period register for Timer3.
If Timer3 is running in Asynchronous Counter mode,
the Reset operation may not work. 
In the event that a write to Timer3 coincides with a
special event trigger from a CCP1 module, the write will
take precedence. 
TABLE 14-1: REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER        
Note: The special event triggers from the
ECCP1 module will not set the TMR3IF
interrupt flag bit (PIR1<0>). 
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR2 OSCFIF CMIF(2) —EEIF BCLIF HLVDIF TMR3IF ECCP1IF(2) 51
PIE2 OSCFIE CMIE(2) —EEIE BCLIE HLVDIE TMR3IE ECCP1IE(2) 52
IPR2 OSCFIP CMIP(2) —EEIP BCLIP HLVDIP TMR3IP ECCP1IP(2) 51
TMR3L Timer3 Register, Low Byte 51
TMR3H Timer3 Register, High Byte 51
T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50
T3CON RD16 T3ECCP1(1) T3CKPS1 T3CKPS0 T3CCP1(1) T3SYNC TMR3CS TMR3ON 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer3 module.
Note 1: These bits are available in PIC18F4X8X devices only.
2: These bits are available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

15.0 CAPTURE/COMPARE/PWM

(CCP1) MODULES

PIC18F2585/2680 devices have one CCP1 module.

PIC18F4585/4680 devices have two CCP1

(Capture/Compare/PWM) modules. CCP1, discussed in

this chapter, implements standard Capture, Compare

and Pulse-Width Modulation (PWM) modes.

ECCP1 implements an Enhanced PWM mode. The

ECCP1 implementation is discussed in Section 16.0

“Enhanced Capture/Compare/PWM (ECCP1)

Module”.

The CCP1 module contains a 16-bit register which can

operate as a 16-bit Capture register, a 16-bit Compare

For the sake of clarity, all CCP1 module operation in the

following sections is described with respect to CCP1,

but is equally applicable to ECCP1.

Capture and Compare operations described in this

chapter apply to all standard and Enhanced CCP1

modules. The operations of PWM mode, described in

Section 15.4 “PWM Mode”, apply to ECCP1 only.

U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

—— DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5-4 DC1B1:DC1B0: PWM Duty Cycle bit 1 and bit 0 for CCP1 Module

Capture mode:

Unused.

Compare mode:

Unused.

PWM mode:

These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs

(DC19:DC12) of the duty cycle are found in ECCPR1L.

bit 3-0 CCP1M3:CCP1M0: CCP1 Module Mode Select bits

0000 = Capture/Compare/PWM disabled (resets CCP1 module)

0001 = Reserved

0010 = Compare mode, toggle output on match (CCP1IF bit is set)

0011 = Reserved

0100 = Capture mode, every falling edge or CAN message received (time-stamp)(1)

0101 = Capture mode, every rising edge or CAN message received (time-stamp)(1)

0110 = Capture mode, every 4th rising edge or every 4th CAN message received

(time-stamp)(1)

0111 = Capture mode, every 16th rising edge or every 16th CAN message received

(time-stamp)(1)

1000 = Compare mode: initialize CCP1 pin low; on compare match, force CCP1 pin high

(CCPIF bit is set)

1001 = Compare mode: initialize CCP pin high; on compare match, force CCP1 pin low

(CCPIF bit is set)

1010 = Compare mode: generate software interrupt on compare match (CCPIF bit is set,

CCP1 pin reflects I/O state)

1011 = Compare mode: trigger special event, reset timer (TMR1 or TMR3, CCP1IF bit is set)

11xx =PWM mode

Note 1: Selected by CANCAP (CIOCON<4>) bit; overrides the CCP1 input pin source.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

15.1 CCP1 Module Configuration

Each Capture/Compare/PWM module is associated

with a control register (CCP1CON or ECCP1CON) and

a data register (CCPR1 or ECCPR1). The data register,

in turn, is comprised of two 8-bit registers: CCPR1L or

ECCPR1L (low byte) and CCPR1H or ECCPR1H (high

byte). All registers are both readable and writable.

15.1.1 CCP1 MODULES AND TIMER

RESOURCES

The CCP1 modules utilize Timers 1, 2 or 3, depending

on the mode selected. Timer1 and Timer3 are available

to modules in Capture or Compare modes, while

Timer2 is available for modules in PWM mode.

TABLE 15-1: CCP1 MODE – TIMER

RESOURCE

The assignment of a particular timer to a module is

determined by the Timer-to-CCP1/ECCP1 enable bits

in the T3CON register (Register 14-1). Both modules

may be active at any given time and may share the

same timer resource if they are configured to operate

in the same mode (Capture/Compare or PWM) at the

same time. The interactions between the two modules

are summarized in Figure 15-1 and Figure 15-2.

TABLE 15-2: INTERACTIONS BETWEEN CCP1 AND ECCP1 FOR TIMER RESOURCES

CCP1/ECCP1 Mode Timer Resource

Capture

Compare

PWM

Timer1 or Timer3

Timer2

CCP1 Mode ECCP1 Mode Interaction

Capture Capture Each module can use TMR1 or TMR3 as the time base. Time base can be different for

each CCP1.

Capture Compare CCP1 can be configured for the special event trigger to reset TMR1 or TMR3

(depending upon which time base is used). Automatic A/D conversions on trigger event

can also be done. Operation of CCP1 could be affected if it is using the same timer as a

time base.

Compare Capture CCP1 can be configured for the special event trigger to reset TMR1 or TMR3

(depending upon which time base is used). Operation of CCP1 could be affected if it is

using the same timer as a time base.

Compare Compare Either module can be configured for the special event trigger to reset the time base.

Automatic A/D conversions on ECCP1 trigger event can be done. Conflicts may occur if

both modules are using the same time base.

Capture PWM* None

Compare PWM* None

PWM* Capture None

PWM* Compare None

PWM* PWM Both PWMs will have the same frequency and update rate (TMR2 interrupt).

* Includes standard and Enhanced PWM operation.

PIC18F2585/2680/4585/4680

15.2 Capture Mode

In Capture mode, the ECCPR1H:ECCPR1L register

pair captures the 16-bit value of the TMR1 or TMR3

registers when an event occurs on the CCP1 pin (RB3

or RC1, depending on device configuration). An event

is defined as one of the following:

• every falling edge

• every rising edge

• every 4th rising edge

• every 16th rising edge

The event is selected by the mode select bits,

CCP1M3:CCP1M0 (CCP1CON<3:0>). When a

capture is made, the interrupt request flag bit, CCP1IF

(PIR2<1>), is set; it must be cleared in software. If

another capture occurs before the value in register

CCPR1 is read, the old captured value is overwritten by

the new captured value.

15.2.1 CCP1 PIN CONFIGURATION

In Capture mode, the appropriate CCP1 pin should be

configured as an input by setting the corresponding

TRIS direction bit.

15.2.2 TIMER1/TIMER3 MODE SELECTION

The timers that are to be used with the capture feature

(Timer1 and/or Timer3) must be running in Timer mode

or Synchronized Counter mode. In Asynchronous

Counter mode, the capture operation may not work.

The timer to be used with each CCP1 module is

selected in the T3CON register (see Section 15.1.1

“CCP1 Modules and Timer Resources”).

15.2.3 SOFTWARE INTERRUPT

When the Capture mode is changed, a false capture

interrupt may be generated. The user should keep the

CCP1IE or ECCP1IE interrupt enable bit clear to avoid

false interrupts. The interrupt flag bit, CCP1IF or

ECCP1IF, should also be cleared following any such

change in operating mode.

15.2.4 CCP1 PRESCALER

There are four prescaler settings in Capture mode; they

are specified as part of the operating mode selected by

the mode select bits (CCP1M3:CCP1M0). Whenever

the CCP1 module is turned off or the CCP1 module is

not in Capture mode, the prescaler counter is cleared.

This means that any Reset will clear the prescaler

counter.

Switching from one capture prescaler to another may

generate an interrupt. Also, the prescaler counter will

not be cleared; therefore, the first capture may be from

a non-zero prescaler. Example 15-1 shows the

recommended method for switching between capture

prescalers. This example also clears the prescaler

counter and will not generate the “false” interrupt.

15.2.5 CAN MESSAGE TIME-STAMP

The CAN capture event occurs when a message is

received in any of the receive buffers. When config-

ured, the CAN module provides the trigger to the CCP1

module to cause a capture event. This feature is

provided to “time-stamp” the received CAN messages.

This feature is enabled by setting the CANCAP bit of

the CAN I/O Control register (CIOCON<4>). The

message receive signal from the CAN module then

takes the place of the events on RC2/CCP1.

If this feature is selected, then four different capture

options for CCP1M<3:0> are available:

•0100 – every time a CAN message is received

•0101 – every time a CAN message is received

•0110 – every 4th time a CAN message is

received

•0111 – Capture mode, every 16th time a CAN

message is received

EXAMPLE 15-1: CHANGING BETWEEN

CAPTURE PRESCALERS

Note: If RC2/CCP1 or RD4/PSP4/ECCP1/P1A

is configured as an output, a write to the

port can cause a capture condition.

CLRF CCP1CON ; Turn CCP1 module off

MOVLW NEW_CAPT_PS ; Load WREG with the

; new prescaler mode

; value and CCP1 ON

MOVWF CCP1CON ; Load CCP1CON with

; this value

PIC18F2585/2680/4585/4680

FIGURE 15-1: CAPTURE MODE OPERATION BLOCK DIAGRAM

CCPR1H CCPR1L

TMR1H TMR1L

Set CCP1IF

TMR3

Enable

Q1:Q4

CCP1CON<3:0>

CCP1 pin

Prescaler

÷ 1, 4, 16

and

Edge Detect

TMR1

Enable

T3ECCP1

ECCPR1H ECCPR1L

TMR1H TMR1L

Set ECCP1IF

TMR3

Enable

ECCP1CON<3:0>

ECCP1 pin

Prescaler

÷ 1, 4, 16

TMR3H TMR3L

TMR1

Enable

T3ECCP1

T3CCP1

T3ECCP1

T3CCP1

TMR3H TMR3L

and

Edge Detect

PIC18F2585/2680/4585/4680

15.3 Compare Mode

In Compare mode, the 16-bit CCPR1 register value is

constantly compared against either the TMR1 or TMR3

pin can be:

• driven high

• driven low

• toggled (high-to-low or low-to-high)

• remain unchanged (that is, reflects the state of the

I/O latch)

The action on the pin is based on the value of the mode

select bits (ECCP1M3:ECCP1M0). At the same time,

the interrupt flag bit ECCP1IF is set.

15.3.1 CCP1 PIN CONFIGURATION

The user must configure the CCP1 (ECCP1) pin as an

output by clearing the appropriate TRIS bit.

15.3.2 TIMER1/TIMER3 MODE SELECTION

Timer1 and/or Timer3 must be running in Timer mode

or Synchronized Counter mode if the CCP1 module is

using the compare feature. In Asynchronous Counter

mode, the compare operation may not work.

15.3.3 SOFTWARE INTERRUPT MODE

When the Generate Software Interrupt mode is chosen

(CCP1M3:CCP1M0 = 1010), the CCP1 pin is not

affected. Only a CCP1 interrupt is generated, if enabled

and the CCP1IE bit is set.

15.3.4 SPECIAL EVENT TRIGGER

Both CCP1 modules are equipped with a special event

trigger. This is an internal hardware signal generated in

Compare mode to trigger actions by other modules.

The special event trigger is enabled by selecting

the Compare Special Event Trigger mode

(CCP1M3:CCP1M0 = 1011).

For either CCP1 module, the special event trigger

resets the timer register pair for whichever timer

resource is currently assigned as the module’s time

base. This allows the CCPR1 (ECCPR1) registers to

serve as a programmable period register for either

timer.

FIGURE 15-2: COMPARE MODE OPERATION BLOCK DIAGRAM

Note: Clearing the CCP1CON register will force

the RC2 compare output latch (depending

on device configuration) to the default low

level. This is not the PORTC I/O data

latch.

CCPR1H CCPR1L

TMR1H TMR1L

Comparator Q

Output

Logic

Special Event Trigger

Set CCP1IF

CCP1 pin

TRIS

CCP1CON<3:0>

Output Enable

TMR3H TMR3L

ECCPR1H ECCPR1L

Comparator

T3ECCP1

T3CCP1

Set CCP1IF

Compare

(Timer1 Reset)

Output

Logic

Special Event Trigger

ECCP1 pin

TRIS

ECCP1CON<3:0>

Output Enable

(Timer1/Timer3 Reset, A/D Trigger)

Match

Compare

Match

PIC18F2585/2680/4585/4680
DS39625C-page 168 Preliminary © 2007 Microchip Technology Inc.
TABLE 15-3: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3    
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
RCON IPEN SBOREN(3) —RI TO PD POR BOR 50
IPR1 PSPIP ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
PIR1 PSPIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR2 OSCFIP CMIP(2) —EEIP BCLIP HLVDIP TMR3IP ECCP1IP(2) 51
PIR2 OSCFIF CMIF(2) —EEIF BCLIF HLVDIF TMR3IF ECCP1IF(2) 52
PIE2 OSCFIE CMIE(2) —EEIE BCLIE HLVDIE TMR3IE ECCP1IE(2) 51
TRISB PORTB Data Direction Register 52
TRISC PORTC Data Direction Register 52
TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register 50
TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register 50
T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50
TMR3H Timer3 Register High Byte 51
TMR3L Timer3 Register Low Byte 51
T3CON RD16 T3ECCP1(1) T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 51
CCPR1L Capture/Compare/PWM Register 1 (LSB) 51
CCPR1H Capture/Compare/PWM Register 1 (MSB) 51
CCP1CON — — DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 51
ECCPR1L(1) Enhanced Capture/Compare/PWM Register 1 (LSB) 51
ECCPR1H(1) Enhanced Capture/Compare/PWM Register 1 (MSB) 51
ECCP1CON(1) EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by Capture and Compare, Timer1 or Timer3.
Note 1: These bits or registers are available on PIC18F4X8X devices only.
2: These bits are available on PIC18F4X8X devices and reserved on PIC18F2X8X devices.
3: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’.

PIC18F2585/2680/4585/4680

15.4 PWM Mode

In Pulse-Width Modulation (PWM) mode, the CCP1 pin

produces up to a 10-bit resolution PWM output. Since

the CCP1 pin is multiplexed with a PORTB or PORTC

data latch, the appropriate TRIS bit must be cleared to

make the CCP1 pin an output.

Figure 15-3 shows a simplified block diagram of the

CCP1 module in PWM mode.

For a step-by-step procedure on how to set up the

CCP1 module for PWM operation, see Section 15.4.4

“Setup for PWM Operation”.

FIGURE 15-3: SIMPLIFIED PWM BLOCK

DIAGRAM

A PWM output (Figure 15-4) has a time base (period)

and a time that the output stays high (duty cycle). The

frequency of the PWM is the inverse of the period

(1/period).

FIGURE 15-4: PWM OUTPUT

15.4.1 PWM PERIOD

The PWM period is specified by writing to the PR2

(PR4) register. The PWM period can be calculated

using the following formula.

EQUATION 15-1:

PWM frequency is defined as 1/[PWM period].

When TMR1 (TMR3) is equal to PR2 (PR2), the

following three events occur on the next increment

cycle:

•TMR2 is cleared

• The CCP1 pin is set (exception: if PWM duty

cycle = 0%, the CCP1 pin will not be set)

• The PWM duty cycle is latched from ECCPR1L

into ECCPR1H

15.4.2 PWM DUTY CYCLE

The PWM duty cycle is specified by writing to the

ECCPR1L register and to the CCP1CON<5:4> bits. Up

to 10-bit resolution is available. The ECCPR1L

contains the eight MSbs and the CCP1CON<5:4> con-

tains the two LSbs. This 10-bit value is represented by

ECCPR1L:ECCP1CON<5:4>. The following equation

is used to calculate the PWM duty cycle in time.

EQUATION 15-2:

ECCPR1L and ECCP1CON<5:4> can be written to at

any time, but the duty cycle value is not latched into

ECCPR1H until after a match between PR2 and TMR2

occurs (i.e., the period is complete). In PWM mode,

ECCPR1H is a read-only register.

Note: Clearing the CCP1CON register will force

the RC2 output latch (depending on

device configuration) to the default low

level. This is not the PORTC I/O data

latch.

CCPR1L

CCPR1H (Slave)

Comparator

TMR2

Comparator

PR2

(Note 1)

Duty Cycle Registers CCP1CON<5:4>

Clear Timer,

CCP1 pin and

latch D.C.

TRISC<2>

RC2/CCP1

Note 1: The 8-bit TMR2 value is concatenated with the 2-bit

internal Q clock, or 2 bits of the prescaler, to create the

10-bit time base.

PORTC<2> Note: The Timer2 postscalers (see Section 13.0

“Timer2 Module”) are not used in the

determination of the PWM frequency. The

postscaler could be used to have a servo

update rate at a different frequency than

the PWM output.

Period

Duty Cycle

TMR2 = PR2

TMR2 = Duty Cycle

TMR2 = PR2

PWM Period = (PR2) + 1] • 4 • TOSC •

(TMR2 Prescale Value)

PWM Duty Cycle = (ECCPR1L:ECCP1CON<5:4>) •

TOSC • (TMR2 Prescal e Value)

PIC18F2585/2680/4585/4680

The ECCPR1H register and a 2-bit internal latch are

used to double-buffer the PWM duty cycle. This

double-buffering is essential for glitchless PWM

operation.

When the ECCPR1H and 2-bit latch match TMR2,

concatenated with an internal 2-bit Q clock or 2 bits of

the TMR2 prescaler, the CCP1 pin is cleared.

The maximum PWM resolution (bits) for a given PWM

frequency is given by the equation.

EQUATION 15-3:

TABLE 15-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz

15.4.3 PWM AUTO-SHUTDOWN

(ECCP1 ONLY)

The PWM auto-shutdown features of the Enhanced

CCP1 module are available to ECCP1 in

PIC18F4585/4680 (40/44-pin) devices. The operation

of this feature is discussed in detail in Section 16.4.7

“Enhanced PWM Auto-Shutdown”.

Auto-shutdown features are not available for CCP1.

15.4.4 SETUP FOR PWM OPERATION

The following steps should be taken when configuring

the CCP1 module for PWM operation:

1. Set the PWM period by writing to the PR2

2. Set the PWM duty cycle by writing to the

CCPR1L register and CCP1CON<5:4> bits.

3. Make the CCP1 pin an output by clearing the

appropriate TRIS bit.

4. Set the TMR2 prescale value, then enable

Timer2 by writing to T2CON.

5. Configure the CCP1 module for PWM operation.

Note: If the PWM duty cycle value is longer than

the PWM period, the ECCP1 pin will not

be cleared.

PWM Resolution (max) =

FOSC

FPWM

log

log(2) bits

⎛

⎝

⎞

⎠

PWM Frequency 2.44 kHz 9.77 kHz 39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz

Timer Prescaler (1, 4, 16)1641111

PR2 Value FFh FFh FFh 3Fh 1Fh 17h

Maximum Resolution (bits) 14 12 10 8 7 6.58

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 171
PIC18F2585/2680/4585/4680
TABLE 15-5: REGISTERS ASSOCIATED WITH PWM AND TIMER2     
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
RCON IPEN SBOREN(2) —RI TO PD POR BOR 50
PIR1 PSPIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
TRISB PORTB Data Direction Register 52
TRISC PORTC Data Direction Register 52
TMR2 Timer2 Module Register 50
PR2 Timer2 Module Period Register 50
T2CON — T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 50
CCPR1L(1) Capture/Compare/PWM Register 1 (LSB) 51
CCPR1H(1) Capture/Compare/PWM Register 1 (MSB) 51
CCP1CON —— DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 51
ECCPR1L(1) Enhanced Capture/Compare/PWM Register 1 (LSB) 51
ECCPR1H(1) Enhanced Capture/Compare/PWM Register 1 (MSB) 51
ECCP1CON(1) EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by PWM or Timer2.
Note 1: These registers are unimplemented on PIC18F2X8X devices.
2: The SBOREN bit is only available when CONFIG2L<1:0> = 01; otherwise, it is disabled and reads as ‘0’.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

16.0 ENHANCED

CAPTURE/COMPARE/PWM

(ECCP1) MODULE

In PIC18F4585/4680 devices, ECCP1 is implemented

as a standard CCP1 module with Enhanced PWM

capabilities. These include the provision for 2 or 4

output channels, user selectable polarity, dead-band

control and automatic shutdown and restart. The

enhanced features are discussed in detail in

Section 16.4 “Enhanced PWM Mode”. Capture,

Compare and single output PWM functions of the

ECCP1 module are the same as described for the

standard CCP1 module.

The control register for the Enhanced CCP1 module is

shown in Register 16-1. It differs from the CCP1CON

two Most Significant bits are implemented to control

PWM functionality.

Note: The ECCP1 module is implemented only

in PIC18F4X8X (40/44-pin) devices.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0

bit 7 bit 0

bit 7-6 EPWM1M1:EPWM1M0: Enhanced PWM Output Configuration bits

If ECCP1M3:ECCP1M2 = 00, 01, 10:

xx = P1A assigned as Capture/Compare input/output; P1B, P1C, P1D assigned as port pins

If ECCP1M3:ECCP1M2 = 11:

00 = Single output: P1A modulated; P1B, P1C, P1D assigned as port pins

01 = Full-bridge output forward: P1D modulated; P1A active; P1B, P1C inactive

10 = Half-bridge output: P1A, P1B modulated with dead-band control; P1C, P1D assigned

as port pins

11 = Full-bridge output reverse: P1B modulated; P1C active; P1A, P1D inactive

bit 5-4 EDC1B1:EDC1B0: PWM Duty Cycle bit 1 and bit 0

Capture mode:

Unused.

Compare mode:

Unused.

PWM mode:

These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are

found in CCPR1L/ECCPR1L.

bit 3-0 ECCP1M3:ECCP1M0: Enhanced CCP1 Mode Select bits

0000 = Capture/Compare/PWM off (resets ECCP1 module)

0001 = Reserved

0010 = Compare mode, toggle output on match

0011 = Reserved

0100 = Capture mode, every falling edge

0101 = Capture mode, every rising edge

0110 = Capture mode, every 4th rising edge

0111 = Capture mode, every 16th rising edge

1000 = Compare mode, initialize ECCP1 pin low, set output on compare match (set ECCP1IF)

1001 = Compare mode, initialize ECCP1 pin high, clear output on compare match (set ECCP1IF)

1010 = Compare mode, generate software interrupt only, ECCP1 pin reverts to I/O state

1011 = Compare mode, trigger special event (ECCP1 resets TMR1 or TMR3, sets ECCP1IF bit

and starts the A/D conversion on ECCP1 match)

1100 = PWM mode; P1A, P1C active-high; P1B, P1D active-high

1101 = PWM mode; P1A, P1C active-high; P1B, P1D active-low

1110 = PWM mode; P1A, P1C active-low; P1B, P1D active-high

1111 = PWM mode; P1A, P1C active-low; P1B, P1D active-low

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680
DS39625C-page 174 Preliminary © 2007 Microchip Technology Inc.
In addition to the expanded range of modes available
through the CCP1CON register, the ECCP1 module
has two additional registers associated with Enhanced
PWM operation and auto-shutdown features. They are:
• ECCP1DEL (Dead-band delay) 
• ECCP1AS (Auto-shutdown configuration)
16.1 ECCP1 Outputs and Configuration 
The Enhanced CCP1 module may have up to four
PWM outputs, depending on the selected operating
mode. These outputs, designated P1A through P1D,
are multiplexed with I/O pins on PORTC and PORTD.
The outputs that are active depend on the CCP1
operating mode selected. The pin assignments are
summarized in Table 16-1.
To configure the I/O pins as PWM outputs, the proper
PWM mode must be selected by setting the
EPWM1M1:EPWM1M0 and CCP1M3:CCP1M0 bits.
The appropriate TRISC and TRISD direction bits for the
port pins must also be set as outputs.
16.1.1 ECCP1 MODULES AND TIMER 
RESOURCES
Like the standard CCP1 modules, the ECCP1 module
can utilize Timers 1, 2 or 3, depending on the mode
selected. Timer1 and Timer3 are available for modules
in Capture or Compare modes, while Timer2 is
available for modules in PWM mode. Interactions
between the standard and Enhanced CCP1 modules
are identical to those described for standard CCP1
modules. Additional details on timer resources are
provided in Section 15.1.1 “CCP1 Modules and
Timer Resources”.
16.2 Capture and Compare Modes
Except for the operation of the special event trigger
discussed below, the Capture and Compare modes of
the ECCP1 module are identical in operation to that of
CCP1. These are discussed in detail in Section 15.2
“Capture Mode” and Section 15.3 “Compare Mode”.
16.2.1 SPECIAL EVENT TRIGGER
The special event trigger output of ECCP1 resets the
TMR1 or TMR3 register pair, depending on which timer
resource is currently selected. This allows the ECCP1
register to effectively be a 16-bit programmable period
register for Timer1 or Timer3. The special event trigger
for ECCP1 can also start an A/D conversion. In order to
start the conversion, the A/D converter must be
previously enabled.
16.3 Standard PWM Mode
When configured in Single Output mode, the ECCP1
module functions identically to the standard CCP1
module in PWM mode, as described in Section 15.4
“PWM Mode”. This is also sometimes referred to as
“Compatible CCP1” mode, as in Table 16-1.
TABLE 16-1: PIN ASSIGNMENTS FOR VARIOUS ECCP1 MODES  
Note: When setting up single output PWM
operations, users are free to use either of the
processes described in Section 15.4.4
“Setup for PWM Operation” or
Section 16.4.9 “Setup for PWM Operation”.
The latter is more generic but will work for
either single or multi-output PWM.
ECCP1 Mode CCP1CON
Configuration RD4 RD5 RD6 RD7
All PIC18F4585/4680 devices:
Compatible CCP1 00xx 11xx CCP1 RD5/PSP5 RD6/PSP6 RD7/PSP7
Dual PWM 10xx 11xx P1A P1B RD6/PSP6 RD7/PSP7
Quad PWM x1xx 11xx P1A P1B P1C P1D
Legend: x = Don’t care. Shaded cells indicate pin assignments not used by ECCP1 in a given mode.

PIC18F2585/2680/4585/4680

16.4 Enhanced PWM Mode

The Enhanced PWM mode provides additional PWM

output options for a broader range of control applica-

tions. The module is a backward compatible version of

the standard CCP1 module and offers up to four out-

puts, designated P1A through P1D. Users are also able

to select the polarity of the signal (either active-high or

active-low). The module’s output mode and polarity are

configured by setting the EPWM1M1:EPWM1M0 and

CCP1M3:CCP1M0 bits of the ECCP1CON register.

Figure 16-1 shows a simplified block diagram of PWM

operation. All control registers are double-buffered and

are loaded at the beginning of a new PWM cycle (the

period boundary when Timer2 resets) in order to

prevent glitches on any of the outputs. The exception is

the PWM Delay register, ECCP1DEL, which is loaded

at either the duty cycle boundary or the boundary

period (whichever comes first). Because of the buffer-

ing, the module waits until the assigned timer resets

instead of starting immediately. This means that

Enhanced PWM waveforms do not exactly match the

standard PWM waveforms but are instead offset by

one full instruction cycle (4 TOSC).

As before, the user must manually configure the

appropriate TRIS bits for output.

16.4.1 PWM PERIOD

The PWM period is specified by writing to the PR2

following equation.

EQUATION 16-1:

PWM frequency is defined as 1/[PWM period]. When

TMR2 is equal to PR2, the following three events occur

on the next increment cycle:

•TMR2 is cleared

• The ECCP1 pin is set (if PWM duty cycle = 0%,

the ECCP1 pin will not be set)

• The PWM duty cycle is copied from ECCPR1L

into ECCPR1H

FIGURE 16-1: SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE

Note: The Timer2 postscaler (see Section 13.0

“Timer2 Module”) is not used in the

determination of the PWM frequency. The

postscaler could be used to have a servo

update rate at a different frequency than

the PWM output.

PWM Period = [(PR2) + 1] • 4 • TOSC •

(TMR2 Prescale Valu e)

ECCPR1L

ECCPR1H (Slave)

Comparator

TMR2

Comparator

PR2

(Note 1)

Duty Cycle Registers CCP1CON<5:4>

Clear Timer,

set ECCP1 pin and

latch D.C.

Note: The 8-bit TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base.

TRISD<4>

ECCP1/P1A

TRISD<5>

P1B

TRISD<6>

TRISD<7>

P1D

Output

Controller

EPWM1M1<1:0>

CCP1M<3:0>

ECCP1DEL

ECCP1/P1A

P1B

P1C

P1D

P1C

PIC18F2585/2680/4585/4680

16.4.2 PWM DUTY CYCLE

The PWM duty cycle is specified by writing to the

ECCPR1L register and to the ECCP1CON<5:4> bits.

Up to 10-bit resolution is available. The ECCPR1L

contains the eight MSbs and the ECCP1CON<5:4>

contains the two LSbs. This 10-bit value is represented

by ECCPR1L:ECCP1CON<5:4>. The PWM duty cycle

is calculated by the following equation.

EQUATION 16-2:

ECCPR1L and ECCP1CON<5:4> can be written to at

any time, but the duty cycle value is not copied into

ECCPR1H until a match between PR2 and TMR2

occurs (i.e., the period is complete). In PWM mode,

ECCPR1H is a read-only register.

The ECCPR1H register and a 2-bit internal latch are

used to double-buffer the PWM duty cycle. This

double-buffering is essential for glitchless PWM opera-

tion. When the ECCPR1H and 2-bit latch match TMR2,

concatenated with an internal 2-bit Q clock or two bits

of the TMR2 prescaler, the ECCP1 pin is cleared. The

maximum PWM resolution (bits) for a given PWM

frequency is given by the following equation.

EQUATION 16-3:

16.4.3 PWM OUTPUT CONFIGURATIONS

The EPWM1M1:EPWM1M0 bits in the ECCP1CON

• Single Output

• Half-Bridge Output

• Full-Bridge Output, Forward mode

• Full-Bridge Output, Reverse mode

The Single Output mode is the standard PWM mode

discussed in Section 16.4 “Enhanced PWM Mode”.

The Half-Bridge and Full-Bridge Output modes are

covered in detail in the sections that follow.

The general relationship of the outputs in all

configurations is summarized in Figure 16-2.

TABLE 16-2: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz

PWM Duty Cycle = (ECCPR1L:ECCP1CON<5:4> •

TOSC • (TMR2 Presc al e Value)

Note: If the PWM duty cycle value is longer than

the PWM period, the CCP1 pin will not be

cleared.

()

PWM Resolution (max) =

FOSC

FPWM

log

log(2) bits

PWM Frequency 2.44 kHz 9.77 kHz 39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz

Timer Prescaler (1, 4, 16)1641111

PR2 Value FFh FFh FFh 3Fh 1Fh 17h

Maximum Resolution (bits) 10 10 10 8 7 6.58

PIC18F2585/2680/4585/4680

FIGURE 16-2: PWM OUTPUT RELATIONSHIPS (ACTIVE-HIGH STATE)

FIGURE 16-3: PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)

Period

SIGNAL PR2 + 1

ECCP1CON

<7:6>

P1A Modulated

P1B Modulated

P1A Active

P1B Inactive

P1C Inactive

P1D Modulated

P1A Inactive

P1B Modulated

P1C Active

P1D Inactive

Duty

Cycle

(Single Output)

(Half-Bridge)

(Full-Bridge,

Forward)

(Full-Bridge,

Reverse)

Delay(1) Delay(1)

Period

SIGNAL PR2 + 1

ECCP1CON

<7:6>

P1A Modulated

P1B Modulated

P1A Active

P1B Inactive

P1C Inactive

P1D Modulated

P1A Inactive

P1B Modulated

P1C Active

P1D Inactive

Duty

Cycle

(Single Output)

(Half-Bridge)

(Full-Bridge,

Forward)

(Full-Bridge,

Reverse)

Delay(1) Delay(1)

Relationships:

• Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)

• Duty Cycle = TOSC * (ECCPR1L<7:0>:ECCP1CON<5:4>) * (TMR2 Prescale Value)

• Delay = 4 * TOSC * (ECCP1DEL<6:0>)

Note1: Dead-band delay is programmed using the ECCP1DEL register (Section 16.4.6 “Programmable Dead-Band Delay”).

PIC18F2585/2680/4585/4680

16.4.4 HALF-BRIDGE MODE

In the Half-Bridge Output mode, two pins are used as

outputs to drive push-pull loads. The PWM output

signal is output on the P1A pin, while the complemen-

tary PWM output signal is output on the P1B pin

(Figure 16-4). This mode can be used for half-bridge

applications, as shown in Figure 16-5, or for full-bridge

applications where four power switches are being

modulated with two PWM signals.

In Half-Bridge Output mode, the programmable

dead-band delay can be used to prevent shoot-through

current in half-bridge power devices. The value of bits,

PDC6:PDC0, sets the number of instruction cycles

before the output is driven active. If the value is greater

than the duty cycle, the corresponding output remains

inactive during the entire cycle. See Section 16.4.6

“Programmable Dead-Band Delay” for more details

of the dead-band delay operations.

Since the P1A and P1B outputs are multiplexed with

the PORTD<4> and PORTD<5> data latches, the

TRISD<4> and TRISD<5> bits must be cleared to

configure P1A and P1B as outputs.

FIGURE 16-4: HALF-BRIDGE PWM

OUTPUT

FIGURE 16-5: EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS

Period

Duty Cycle

(1)

P1A(2)

P1B(2)

td = Dead-Band Delay

Period

(1) (1)

Note 1: At this time, the TMR2 register is equal to the

PR2 register.

2: Output signals are shown as active-high.

PIC18FX585/X680

P1A

P1B

FET

Driver

FET

Driver

V+

V-

Load

FET

Driver

FET

Driver

V+

V-

Load

FET

Driver

FET

Driver

PIC18FX585/X680

P1A

P1B

Standard Half-Bridge Circuit (“Push-Pull”)

Half-Bridge Output Driving a Full-Bridge Circuit

PIC18F2585/2680/4585/4680

16.4.5 FULL-BRIDGE MODE

In Full-Bridge Output mode, four pins are used as

outputs; however, only two outputs are active at a time.

In the Forward mode, pin P1A is continuously active

and pin P1D is modulated. In the Reverse mode, pin

P1C is continuously active and pin P1B is modulated.

These are illustrated in Figure 16-6.

P1A, P1B, P1C and P1D outputs are multiplexed with

the PORTD<4>, PORTD<5>, PORTD<6> and

PORTD<7> data latches. The TRISD<4>, TRISD<5>,

TRISD<6> and TRISD<7> bits must be cleared to

make the P1A, P1B, P1C and P1D pins outputs.

FIGURE 16-6: FULL-BRIDGE PWM OUTPUT

Period

Duty Cycle

P1A(2)

P1B(2)

P1C(2)

P1D(2)

Forward Mode

(1)

Period

Duty Cycle

P1A(2)

P1C(2)

P1D(2)

P1B(2)

Reverse Mode

(1)

Note 1: At this time, the TMR2 register is equal to the PR2 register.

Note 2: Output signal is shown as active-high.

PIC18F2585/2680/4585/4680

FIGURE 16-7: EXAMPLE OF FULL-BRIDGE APPLICATION

16.4.5.1 Direction Change in Full-Bridge Mode

In the Full-Bridge Output mode, the EPWM1M1 bit in

the CCP1CON register allows the user to control the

forward/reverse direction. When the application

firmware changes this direction control bit, the module

will assume the new direction on the next PWM cycle.

Just before the end of the current PWM period, the

modulated outputs (P1B and P1D) are placed in their

inactive state, while the unmodulated outputs (P1A and

P1C) are switched to drive in the opposite direction.

This occurs in a time interval of (4 TOSC * (Timer2

Prescale Value)) before the next PWM period begins.

The Timer2 prescaler will be either 1, 4 or 16, depend-

ing on the value of the T2CKPS bit (T2CON<1:0>).

During the interval from the switch of the unmodulated

outputs to the beginning of the next period, the

modulated outputs (P1B and P1D) remain inactive.

This relationship is shown in Figure 16-8.

Note that in the Full-Bridge Output mode, the CCP1

module does not provide any dead-band delay. In

general, since only one output is modulated at all times,

dead-band delay is not required. However, there is a

situation where a dead-band delay might be required.

This situation occurs when both of the following

conditions are true:

1. The direction of the PWM output changes when

the duty cycle of the output is at or near 100%.

2. The turn-off time of the power switch, including

the power device and driver circuit, is greater

than the turn-on time.

Figure 16-9 shows an example where the PWM direc-

tion changes from forward to reverse at a near 100%

duty cycle. At time t1, the outputs P1A and P1D

become inactive, while output P1C becomes active. In

this example, since the turn-off time of the power

devices is longer than the turn-on time, a shoot-through

current may flow through power devices, QC and QD

(see Figure 16-7), for the duration of ‘t’. The same

phenomenon will occur to power devices, QA and QB,

for PWM direction change from reverse to forward.

If changing PWM direction at high duty cycle is required

for an application, one of the following requirements

must be met:

1. Reduce PWM for a PWM period before

changing directions.

2. Use switch drivers that can drive the switches off

faster than they can drive them on.

Other options to prevent shoot-through current may

exist.

P1A

P1C

FET

Driver

FET

Driver

V+

V-

Load

FET

Driver

FET

Driver

P1B

P1D

QB QD

PIC18FX585/X680

PIC18F2585/2680/4585/4680

FIGURE 16-8: PWM DIRECTION CHANGE

FIGURE 16-9: PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE

Period(1)

SIGNAL

Note 1: The direction bit in the CCP1 Control register (CCP1CON<7>) is written any time during the PWM cycle.

2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle at

intervals of 4 TOSC, 16 TOSC or 64 TOSC, depending on the Timer2 prescaler value. The modulated P1B and

P1D signals are inactive at this time.

Period

(Note 2)

P1A (Active-High)

P1B (Active-High)

P1C (Active-High)

P1D (Active-High)

Forward Period Reverse Period

P1A(1)

tON(2)

tOFF(3)

t = tOFF – tON(2,3)

P1B(1)

P1C(1)

P1D(1)

External Switch D(1)

Potential

Shoot-Through

Current(1)

Note 1: All signals are shown as active-high.

2: tON is the turn-on delay of power switch QC and its driver.

3: tOFF is the turn-off delay of power switch QD and its driver.

External Switch C(1)

PIC18F2585/2680/4585/4680

16.4.6

PROGRAMMABLE DEAD-BAND

DELAY

In half-bridge applications where all power switches are

modulated at the PWM frequency at all times, the power

switches normally require more time to turn off than to

turn on. If both the upper and lower power switches are

switched at the same time (one turned on and the other

turned off), both switches may be on for a short period of

time until one switch completely turns off. During this

brief interval, a very high current (

shoot-through current

)

may flow through both power switches, shorting the

bridge supply. To avoid this potentially destructive

shoot-through current from flowing during switching,

turning on either of the power switches is normally

delayed to allow the other switch to completely turn off.

In the Half-Bridge Output mode, a digitally program-

mable dead-band delay is available to avoid

shoot-through current from destroying the bridge

power switches. The delay occurs at the signal transi-

tion from the non-active state to the active state. See

Figure 16-4 for illustration. Bits PDC6:PDC0 of the

ECCP1DEL register (Register 16-2) set the delay

period in terms of microcontroller instruction cycles

(TCY or 4 TOSC). These bits are not available on

PIC18F2X8X devices, as the standard CCP1 module

does not support half-bridge operation.

16.4.7

ENHANCED PWM AUTO-SHUTDOWN

When the CCP1 is programmed for any of the Enhanced

PWM modes, the active output pins may be configured

for auto-shutdown. Auto-shutdown immediately places

the Enhanced PWM output pins into a defined shutdown

state when a shutdown event occurs.

A shutdown event can be caused by either of the

comparator modules, a low level on the

RB0/INT0/FLT0/AN10 pin, or any combination of these

three sources. The comparators may be used to monitor

a voltage input proportional to a current being monitored

in the bridge circuit. If the voltage exceeds a threshold,

the comparator switches state and triggers a shutdown.

Alternatively, a digital signal on the INT0 pin can also

trigger a shutdown. The auto-shutdown feature can be

disabled by not selecting any auto-shutdown sources.

The auto-shutdown sources to be used are selected

using the ECCPAS2:ECCPAS0 bits (bits<6:4> of the

ECCP1AS register).

When a shutdown occurs, the output pins are asyn-

chronously placed in their shutdown states, specified

by the PSSAC1:PSSAC0 and PSS1BD1:PSS1BD0

bits (ECCPAS3:ECCPAS0). Each pin pair (P1A/P1C

and P1B/P1D) may be set to drive high, drive low or be

tri-stated (not driving). The ECCPASE bit

(ECCP1AS<7>) is also set to hold the Enhanced PWM

outputs in their shutdown states.

The ECCPASE bit is set by hardware when a shutdown

event occurs. If automatic restarts are not enabled, the

ECCPASE bit is cleared by firmware when the cause of

the shutdown clears. If automatic restarts are enabled,

the ECCPASE bit is automatically cleared when the

cause of the auto-shutdown has cleared.

If the ECCPASE bit is set when a PWM period begins,

the PWM outputs remain in their shutdown state for that

entire PWM period. When the ECCPASE bit is cleared,

the PWM outputs will return to normal operation at the

beginning of the next PWM period.

Note: Programmable dead-band delay is not

implemented in PIC18F2X8X devices with

standard CCP1 modules.

Note: Writing to the ECCPASE bit is disabled

while a shutdown condition is active.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

PRSEN PDC6(1) PDC5(1) PDC4(1) PDC3(1) PDC2(1) PDC1(1) PDC0(1)

bit 7 bit 0

bit 7 PRSEN: PWM Restart Enable bit

1 = Upon auto-shutdown, the ECCPASE bit clears automatically once the shutdown event

goes away; the PWM restarts automatically

0 = Upon auto-shutdown, ECCPASE must be cleared in software to restart the PWM

bit 6-0 PDC6:PDC0: PWM Delay Count bits(1)

Delay time, in number of FOSC/4 (4 * TOSC) cycles, between the scheduled and actual time for

a PWM signal to transition to active.

Note 1: Reserved on PIC18F2X8X devices; maintain these bits clear.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

CONTROL REGISTER

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1)

bit 7 bit 0

bit 7 ECCPASE: ECCP1 Auto-Shutdown Event Status bit

1 = A shutdown event has occurred; ECCP1 outputs are in shutdown state

0 = ECCP1 outputs are operating

bit 6-4 ECCPAS2:ECCPAS0: ECCP1 Auto-Shutdown Source Select bits

111 = RB0 or Comparator 1 or Comparator 2

110 = RB0 or Comparator 2

101 = RB0 or Comparator 1

100 = RB0

011 = Either Comparator 1 or 2

010 = Comparator 2 output

001 = Comparator 1 output

000 = Auto-shutdown is disabled

bit 3-2 PSSAC1:PSSAC0: Pins A and C Shutdown State Control bits

1x = Pins A and C tri-state (PIC18F4X8X devices);

01 = Drive Pins A and C to ‘1’

00 = Drive Pins A and C to ‘0’

bit 1-0 PSSBD1:PSSBD0: Pins B and D Shutdown State Control bits(1)

1x = Pins B and D tri-state

01 = Drive Pins B and D to ‘1’

00 = Drive Pins B and D to ‘0’

Note 1: Reserved on PIC18F2X8X devices; maintain these bits clear.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

16.4.7.1 Auto-Shutdown and Auto-Restart

The auto-shutdown feature can be configured to allow

automatic restarts of the module following a shutdown

event. This is enabled by setting the PRSEN bit of the

ECCP1DEL register (ECCP1DEL<7>).

In Shutdown mode with PRSEN = 1 (Figure 16-10), the

ECCPASE bit will remain set for as long as the cause

of the shutdown continues. When the shutdown condi-

tion clears, the ECCP1ASE bit is cleared. If PRSEN = 0

(Figure 16-11), once a shutdown condition occurs, the

ECCPASE bit will remain set until it is cleared by

firmware. Once ECCPASE is cleared, the Enhanced

PWM will resume at the beginning of the next PWM

period.

Independent of the PRSEN bit setting, if the

auto-shutdown source is one of the comparators, the

shutdown condition is a level. The ECCPASE bit

cannot be cleared as long as the cause of the shutdown

persists.

The Auto-Shutdown mode can be forced by writing a ‘1’

to the ECCPASE bit.

16.4.8 START-UP CONSIDERATIONS

When the ECCP1 module is used in the PWM mode, the

application hardware must use the proper external pull-up

and/or pull-down resistors on the PWM output pins. When

the microcontroller is released from Reset, all of the I/O

pins are in the high-impedance state. The external circuits

must keep the power switch devices in the off state until

the microcontroller drives the I/O pins with the proper

signal levels, or activates the PWM output(s).

The ECCP1M1:ECCP1M0 bits (ECCP1CON<1:0>)

allow the user to choose whether the PWM output sig-

nals are active-high or active-low for each pair of PWM

output pins (P1A/P1C and P1B/P1D). The PWM output

polarities must be selected before the PWM pins are

configured as outputs. Changing the polarity configura-

tion while the PWM pins are configured as outputs is

not recommended, since it may result in damage to the

application circuits.

The P1A, P1B, P1C and P1D output latches may not be

in the proper states when the PWM module is initialized.

Enabling the PWM pins for output at the same time as

the ECCP1 module may cause damage to the applica-

tion circuit. The ECCP1 module must be enabled in the

proper output mode and complete a full PWM cycle

before configuring the PWM pins as outputs. The com-

pletion of a full PWM cycle is indicated by the TMR2IF

bit being set as the second PWM period begins.

FIGURE 16-10: PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED)

FIGURE 16-11: PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED)

Note: Writing to the ECCPASE bit is disabled

while a shutdown condition is active.

Shutdown

PWM

ECCPASE bit

Activity

Event

Shutdown

Event Occurs

Shutdown

Event Clears

PWM

Resumes

Normal PWM

Start of

PWM Period

Shutdown

PWM

ECCPASE bit

Activity

Event

Shutdown

Event Occurs

Shutdown

Event Clears

PWM

Resumes

Normal PWM

Start of

PWM Period

ECCPASE

Cleared by

Firmware

PWM Period

PIC18F2585/2680/4585/4680

16.4.9 SETUP FOR PWM OPERATION

The following steps should be taken when configuring

the ECCP1 module for PWM operation:

1. Configure the PWM pins P1A and P1B (and

P1C and P1D, if used) as inputs by setting the

corresponding TRIS bits.

2. Set the PWM period by loading the PR2 register.

3. Configure the ECCP1 module for the desired

PWM mode and configuration by loading the

ECCP1CON register with the appropriate

values:

• Select one of the available output

configurations and direction with the

EPWM1M1:EPWM1M0 bits.

• Select the polarities of the PWM output

signals with the ECCP1M3:ECCP1M0 bits.

4. Set the PWM duty cycle by loading the

ECCPR1L register and ECCP1CON<5:4> bits.

5. For Half-Bridge Output mode, set the

dead-band delay by loading ECCP1DEL<6:0>

with the appropriate value.

6. If auto-shutdown operation is required, load the

ECCP1AS register:

• Select the auto-shutdown sources using the

ECCPAS2:ECCPAS0 bits.

• Select the shutdown states of the PWM

output pins using PSSAC1:PSSAC0 and

PSSBD1:PSSBD0 bits.

• Set the ECCPASE bit (ECCP1AS<7>).

• Configure the comparators using the CMCON

• Configure the comparator inputs as analog

inputs.

7. If auto-restart operation is required, set the

PRSEN bit (ECCP1DEL<7>).

8. Configure and start TMR2:

• Clear the TMR2 interrupt flag bit by clearing

the TMR2IF bit (PIR1<1>).

• Set the TMR2 prescale value by loading the

T2CKPS bits (T2CON<1:0>).

• Enable Timer2 by setting the TMR2ON bit

(T2CON<2>).

9. Enable PWM outputs after a new PWM cycle

has started:

• Wait until TMRn overflows (TMRnIF bit is set).

• Enable the ECCP1/P1A, P1B, P1C and/or

P1D pin outputs by clearing the respective

TRIS bits.

• Clear the ECCPASE bit (ECCP1AS<7>).

16.4.10 EFFECTS OF A RESET

Both Power-on Reset and subsequent Resets will force

all ports to Input mode and the CCP1 registers to their

Reset states.

This forces the Enhanced CCP1 module to reset to a

state compatible with the standard CCP1 module.

PIC18F2585/2680/4585/4680
DS39625C-page 186 Preliminary © 2007 Microchip Technology Inc.
TABLE 16-3: REGISTERS ASSOCIATED WITH ECCP1 MODULE AND TIMER1 TO TIMER3     
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
RCON IPEN SBOREN —RI TO PD POR BOR 50
IPR1 PSPIP ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
PIR1 PSPIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR2 OSCFIP CMIP(3) —EEIP BCLIP HLVDIP TMR3IP ECCP1IP(3) 51
PIR2 OSCFIF CMIF(3) —EEIF BCLIF HLVDIF TMR3IF ECCP1IF(3) 51
PIE2 OSCFIE CMIE(3) —EEIE BCLIE HLVDIE TMR3IE ECCP1IE(3) 52
TRISB PORTB Data Direction Register 52
TRISC PORTC Data Direction Register 52
TRISD(1) PORTD Data Direction Register 52
TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register 50
TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register 50
T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50
TMR2 Timer2 Module Register 50
T2CON — T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 50
PR2 Timer2 Period Register 50
TMR3L Holding Register for the Least Significant Byte of the 16-bit TMR3 Register 51
TMR3H Holding Register for the Most Significant Byte of the 16-bit TMR3 Register 51
T3CON RD16 T3ECCP1(1) T3CKPS1 T3CKPS0 T3CCP1(1) T3SYNC TMR3CS TMR3ON 51
ECCPR1L(2) Enhanced Capture/Compare/PWM Register 1 (LSB) 51
ECCPR1H(2) Enhanced Capture/Compare/PWM Register 1 (MSB) 51
ECCP1CON(2) EPWM1M1 EPWM1M0 EDC1B1 EDC1B0 ECCP1M3 ECCP1M2 ECCP1M1 ECCP1M0 51
ECCP1AS(2) ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(2) PSSBD0(2) 51
ECCP1DEL(2) PRSEN PDC6(2) PDC5(2) PDC4(2) PDC3(2) PDC2(2) PDC1(2) PDC0(2) 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used during ECCP1 operation.
Note 1: These bits are available on PIC18F4X8X devices only.
2: These bits or registers are unimplemented in PIC18F2X8X devices; always maintain these bit clear.
3: These bits are available on PIC18F4X8X and reserved on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

17.0 MASTER SYNCHRONOUS

SERIAL PORT (MSSP)

MODULE

17.1 Master SSP (MSSP) Module

Overview

The Master Synchronous Serial Port (MSSP) module is

a serial interface, useful for communicating with other

peripheral or microcontroller devices. These peripheral

devices may be serial EEPROMs, shift registers,

display drivers, A/D converters, etc. The MSSP module

can operate in one of two modes:

• Serial Peripheral Interface (SPI)

• Inter-Integrated Circuit (I2C)

- Full Master mode

- Slave mode (with general address call)

The I2C interface supports the following modes in

hardware:

•Master mode

• Multi-Master mode

• Slave mode

17.2 Control Registers

The MSSP module has three associated registers.

These include a status register (SSPSTAT) and two

control registers (SSPCON1 and SSPCON2). The use

of these registers and their individual configuration bits

differ significantly depending on whether the MSSP

module is operated in SPI or I2C mode.

Additional details are provided under the individual

sections.

17.3 SPI Mode

The SPI mode allows 8 bits of data to be synchronously

transmitted and received simultaneously. All four

modes of SPI are supported. To accomplish

communication, typically three pins are used:

• Serial Data Out (SDO) – RC5/SDO

• Serial Data In (SDI) – RC4/SDI/SDA

• Serial Clock (SCK) – RC3/SCK/SCL

Additionally, a fourth pin may be used when in a Slave

mode of operation:

• Slave Select (SS) – RA5/AN4/SS/HLVDIN

Figure 17-1 shows the block diagram of the MSSP

module when operating in SPI mode.

FIGURE 17-1: MSSP BLOCK DIAGRAM

(SPI MODE)

( )

Read Write

Internal

Data Bus

SSPSR reg

SSPM3:SSPM0

bit 0 Shift

Clock

SS Control

Enable

Edge

Select

Clock Select

TMR2 Output

OSC

Prescaler

4, 16, 64

Edge

Select

Data to TX/RX in SSPSR

TRIS bit

SMP:CKE

RC5/SDO

SSPBUF reg

RC4/SDI/SDA

RA5/AN4/SS/HLVDIN

RC3/SCK/SCL

PIC18F2585/2680/4585/4680

17.3.1 REGISTERS

The MSSP module has four registers for SPI mode

operation. These are:

• MSSP Control Register 1 (SSPCON1)

• MSSP Status Register (SSPSTAT)

• Serial Receive/Transmit Buffer Register

(SSPBUF)

• MSSP Shift Register (SSPSR) – Not directly

accessible

SSPCON1 and SSPSTAT are the control and status

registers in SPI mode operation. The SSPCON1

the SSPSTAT are read-only. The upper two bits of the

SSPSTAT are read/write.

SSPSR is the shift register used for shifting data in or

out. SSPBUF is the buffer register to which data bytes

are written to or read from.

In receive operations, SSPSR and SSPBUF together

create a double-buffered receiver. When SSPSR

receives a complete byte, it is transferred to SSPBUF

and the SSPIF interrupt is set.

During transmission, the SSPBUF is not double-

buffered. A write to SSPBUF will write to both SSPBUF

and SSPSR.

R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

SMP CKE D/A PSR/WUA BF

bit 7 bit 0

bit 7 SMP: Sample bit

SPI Master mode:

1 = Input data sampled at end of data output time

0 = Input data sampled at middle of data output time

SPI Slave mode:

SMP must be cleared when SPI is used in Slave mode.

bit 6 CKE: SPI Clock Select bit

1 = Transmit occurs on transition from active to Idle clock state

0 = Transmit occurs on transition from Idle to active clock state

Polarity of clock state is set by the CKP bit (SSPCON1<4>).

bit 5 D/A: Data/Address bit

Used in I2C mode only.

bit 4 P: Stop bit

Used in I2C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is

cleared.

bit 3 S: Start bit

Used in I2C mode only.

bit 2 R/W: Read/Write bit Information

Used in I2C mode only.

bit 1 UA: Update Address bit

Used in I2C mode only.

bit 0 BF: Buffer Full Status bit (Receive mode only)

1 = Receive complete, SSPBUF is full

0 = Receive not complete, SSPBUF is empty

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0

bit 7 bit 0

bit 7 WCOL: Write Collision Detect bit (Transmit mode only)

1 = The SSPBUF register is written while it is still transmitting the previous word

(must be cleared in software)

0 = No collision

bit 6 SSPOV: Receive Overflow Indicator bit

SPI Slave mode:

1 = A new byte is received while the SSPBUF register is still holding the previous data. In case

of overflow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user

must read the SSPBUF, even if only transmitting data, to avoid setting overflow (must be

cleared in software).

0 = No overflow

Note: In Master mode, the overflow bit is not set since each new reception (and

transmission) is initiated by writing to the SSPBUF register.

bit 5 SSPEN: Synchronous Serial Port Enable bit

1 = Enables serial port and configures SCK, SDO, SDI and SS as serial port pins

0 = Disables serial port and configures these pins as I/O port pins

Note: When enabled, these pins must be properly configured as input or output.

bit 4 CKP: Clock Polarity Select bit

1 = Idle state for clock is a high level

0 = Idle state for clock is a low level

bit 3-0 SSPM3:SSPM0: Synchronous Serial Port Mode Select bits

0101 = SPI Slave mode, clock = SCK pin, SS pin control disabled, SS can be used as I/O pin

0100 = SPI Slave mode, clock = SCK pin, SS pin control enabled

0011 = SPI Master mode, clock = TMR2 output/2

0010 = SPI Master mode, clock = FOSC/64

0001 = SPI Master mode, clock = FOSC/16

0000 = SPI Master mode, clock = FOSC/4

Note: Bit combinations not specifically listed here are either reserved or implemented in

I2C mode only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

17.3.2 OPERATION

When initializing the SPI, several options need to be

specified. This is done by programming the appropriate

control bits (SSPCON1<5:0> and SSPSTAT<7:6>).

These control bits allow the following to be specified:

• Master mode (SCK is the clock output)

• Slave mode (SCK is the clock input)

• Clock Polarity (Idle state of SCK)

• Data Input Sample Phase (middle or end of data

output time)

• Clock Edge (output data on rising/falling edge of

SCK)

• Clock Rate (Master mode only)

• Slave Select mode (Slave mode only)

The MSSP consists of a transmit/receive shift register

(SSPSR) and a buffer register (SSPBUF). The SSPSR

shifts the data in and out of the device, MSb first. The

SSPBUF holds the data that was written to the SSPSR

until the received data is ready. Once the 8 bits of data

have been received, that byte is moved to the SSPBUF

(SSPSTAT<0>) and the interrupt flag bit, SSPIF, are

set. This double-buffering of the received data

(SSPBUF) allows the next byte to start reception before

reading the data that was just received. Any write to the

SSPBUF register during transmission/reception of data

will be ignored and the write collision detect bit, WCOL

(SSPCON1<7>), will be set. User software must clear

the WCOL bit so that it can be determined if the follow-

ing write(s) to the SSPBUF register completed

successfully.

When the application software is expecting to receive

valid data, the SSPBUF should be read before the next

byte of data to transfer is written to the SSPBUF. The

Buffer Full bit, BF (SSPSTAT<0>), indicates when

SSPBUF has been loaded with the received data

(transmission is complete). When the SSPBUF is read,

the BF bit is cleared. This data may be irrelevant if the

SPI is only a transmitter. Generally, the MSSP interrupt

is used to determine when the transmission/reception

has completed. The SSPBUF must be read and/or

written. If the interrupt method is not going to be used,

then software polling can be done to ensure that a write

collision does not occur. Example 17-1 shows the

loading of the SSPBUF (SSPSR) for data transmission.

The SSPSR is not directly readable or writable and can

only be accessed by addressing the SSPBUF register.

Additionally, the MSSP status register (SSPSTAT)

indicates the various status conditions.

EXAMPLE 17-1: LOADING THE SSPBUF (SSPSR) REGISTER

LOOP BTFSS SSPSTAT, BF ;Has data been received (transmit complete)?

BRA LOOP ;No

MOVF SSPBUF, W ;WREG reg = contents of SSPBUF

MOVWF RXDATA ;Save in user RAM, if data is meaningful

MOVF TXDATA, W ;W reg = contents of TXDATA

MOVWF SSPBUF ;New data to xmit

PIC18F2585/2680/4585/4680

17.3.3 ENABLING SPI I/O

To enable the serial port, SSP Enable bit, SSPEN

(SSPCON1<5>), must be set. To reset or reconfigure

SPI mode, clear the SSPEN bit, reinitialize the SSPCON

registers and then set the SSPEN bit. This configures

the SDI, SDO, SCK and SS pins as serial port pins. For

the pins to behave as the serial port function, some must

have their data direction bits (in the TRIS register)

appropriately programmed as follows:

• SDI is automatically controlled by the SPI module

• SDO must have TRISC<5> bit cleared

• SCK (Master mode) must have TRISC<3> bit

cleared

• SCK (Slave mode) must have TRISC<3> bit set

•SS

must have TRISF<7> bit set

Any serial port function that is not desired may be

overridden by programming the corresponding data

direction (TRIS) register to the opposite value.

17.3.4 TYPICAL CONNECTION

Figure 17-2 shows a typical connection between two

microcontrollers. The master controller (Processor 1)

initiates the data transfer by sending the SCK signal.

Data is shifted out of both shift registers on their

programmed clock edge and latched on the opposite

edge of the clock. Both processors should be

programmed to the same Clock Polarity (CKP), then

both controllers would send and receive data at the

same time. Whether the data is meaningful (or dummy

data) depends on the application software. This leads

to three scenarios for data transmission:

• Master sends data – Slave sends dummy data

• Master sends data – Slave sends data

• Master sends dummy data – Slave sends data

FIGURE 17-2: SPI MASTER/SLAVE CONNECTION

Serial Input Buffer

(SSPBUF)

Shift Register

(SSPSR)

MSb LSb

SDO

SDI

PROCESSOR 1

SCK

SPI Master SSPM3:SSPM0 = 00xxb

Serial Input Buffer

(SSPBUF)

Shift Register

(SSPSR)

LSb

MSb

SDI

SDO

PROCESSOR 2

SCK

SPI Slave SSPM3:SSPM0 = 010xb

Serial Clock

PIC18F2585/2680/4585/4680

17.3.5 MASTER MODE

The master can initiate the data transfer at any time

because it controls the SCK. The master determines

when the slave (Processor 2, Figure 17-2) is to

broadcast data by the software protocol.

In Master mode, the data is transmitted/received as

soon as the SSPBUF register is written to. If the SPI is

only going to receive, the SDO output could be

disabled (programmed as an input). The SSPSR regis-

ter will continue to shift in the signal present on the SDI

pin at the programmed clock rate. As each byte is

received, it will be loaded into the SSPBUF register as

if a normal received byte (interrupts and status bits

appropriately set). This could be useful in receiver

applications as a “Line Activity Monitor” mode.

The clock polarity is selected by appropriately

programming the CKP bit (SSPCON1<4>). This then,

would give waveforms for SPI communication as

shown in Figure 17-3, Figure 17-5 and Figure 17-6,

where the MSB is transmitted first. In Master mode, the

SPI clock rate (bit rate) is user-programmable to be one

of the following:

•F

OSC/4 (or TCY)

•FOSC/16 (or 4 • TCY)

•F

OSC/64 (or 16 • TCY)

• Timer2 output/2

This allows a maximum data rate (at 40 MHz) of

10.00 Mbps.

Figure 17-3 shows the waveforms for Master mode.

When the CKE bit is set, the SDO data is valid before

there is a clock edge on SCK. The change of the input

sample is shown based on the state of the SMP bit. The

time when the SSPBUF is loaded with the received

data is shown.

FIGURE 17-3: SPI MODE WAVEFORM (MASTER MODE)

SCK

(CKP = 0

SCK

(CKP = 1

SCK

(CKP = 0

SCK

(CKP = 1

4 Clock

Modes

Input

Sample

Input

Sample

SDI

bit 7 bit 0

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

bit 7

SDI

SSPIF

(SMP = 1)

(SMP = 0)

(SMP = 1)

CKE = 1)

CKE = 0)

CKE = 1)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

(CKE = 0)

(CKE = 1)

Next Q4 Cycle

after Q2↓

bit 0

PIC18F2585/2680/4585/4680

17.3.6 SLAVE MODE

In Slave mode, the data is transmitted and received as

the external clock pulses appear on SCK. When the

last bit is latched, the SSPIF interrupt flag bit is set.

Before enabling the module in SPI Slave mode, the

clock line must match the proper Idle state. The clock

line can be observed by reading the SCK pin. The Idle

state is determined by the CKP bit (SSPCON1<4>).

While in Slave mode, the external clock is supplied by

the external clock source on the SCK pin. This external

clock must meet the minimum high and low times as

specified in the electrical specifications.

While in Sleep mode, the slave can transmit/receive

data. When a byte is received, the device will wake-up

from Sleep.

17.3.7 SLAVE SELECT

SYNCHRONIZATION

The SS pin allows a Synchronous Slave mode. The

SPI must be in Slave mode with SS pin control enabled

(SSPCON1<3:0> = 04h). The pin must not be driven

low for the SS pin to function as an input. The data latch

must be high. When the SS pin is low, transmission and

reception are enabled and the SDO pin is driven. When

the SS pin goes high, the SDO pin is no longer driven,

even if in the middle of a transmitted byte and becomes

a floating output. External pull-up/pull-down resistors

may be desirable depending on the application.

When the SPI module resets, the bit counter is forced

to ‘0’. This can be done by either forcing the SS pin to

a high level or clearing the SSPEN bit.

To emulate two-wire communication, the SDO pin can

be connected to the SDI pin. When the SPI needs to

operate as a receiver, the SDO pin can be configured

as an input. This disables transmissions from the SDO.

The SDI can always be left as an input (SDI function)

since it cannot create a bus conflict.

FIGURE 17-4: SLAVE SYNCHRONIZATION WAVEFORM

Note 1: When the SPI is in Slave mode with SS pin

control enabled (SSPCON<3:0> = 0100),

the SPI module will reset if the SS pin is set

to VDD.

2: If the SPI is used in Slave mode with CKE

set, then the SS pin control must be

enabled.

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7

SDO bit 7 bit 6 bit 7

SSPIF

Interrupt

(SMP = 0)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

bit 0

bit 7

bit 0

Next Q4 Cycle

after Q2↓

PIC18F2585/2680/4585/4680

FIGURE 17-5: SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0)

FIGURE 17-6: SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 1)

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

SSPIF

Interrupt

(SMP = 0)

CKE = 0)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

Optional

Next Q4 Cycle

after Q2↓

bit 0

SCK

(CKP = 1

SCK

(CKP = 0

Input

Sample

SDI

bit 7 bit 0

SDO bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

SSPIF

Interrupt

(SMP = 0)

CKE = 1)

(SMP = 0)

Write to

SSPBUF

SSPSR to

SSPBUF

Flag

Not Optional

Next Q4 Cycle

after Q2↓

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 195
PIC18F2585/2680/4585/4680
17.3.8 OPERATION IN POWER MANAGED 
MODES
In SPI Master mode, module clocks may be operating
at a different speed than when in full power mode; in
the case of the Sleep mode, all clocks are halted.
In most power managed modes, a clock is provided to
the peripherals. That clock should be from the primary
clock source, the secondary clock (Timer1 oscillator at
32.768 kHz) or the INTOSC source. See Section 2.7
“Clock Sources and Oscillator Switching” for
additional information.
In most cases, the speed that the master clocks SPI
data is not important; however, this should be
evaluated for each system.
If MSSP interrupts are enabled, they can wake the
controller from Sleep mode, or one of the Idle modes,
when the master completes sending data. If an exit
from Sleep or Idle mode is not desired, MSSP
interrupts should be disabled.
If the Sleep mode is selected, all module clocks are
halted and the transmission/reception will remain in
that state until the devices wakes. After the device
returns to Run mode, the module will resume
transmitting and receiving data.
In SPI Slave mode, the SPI Transmit/Receive Shift
register operates asynchronously to the device. This
allows the device to be placed in any power managed
mode and data to be shifted into the SPI Transmit/
Receive Shift register. When all 8 bits have been
received, the MSSP interrupt flag bit will be set and if
enabled, will wake the device.
17.3.9 EFFECTS OF A RESET
A Reset disables the MSSP module and terminates the
current transfer.
17.3.10 BUS MODE COMPATIBILITY
Table 17-1 shows the compatibility between the
standard SPI modes and the states of the CKP and
CKE control bits. 
TABLE 17-1: SPI BUS MODES          
There is also a SMP bit which controls when the data is
sampled.
TABLE 17-2: REGISTERS ASSOCIATED WITH SPI OPERATION       
Standard SPI Mode 
Terminology
Control Bits State
CKP CKE
0, 0 0 1
0, 1 0 0
1, 0 1 1
1, 1 1 0
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
TRISA PORTA Data Direction Register 52
TRISC PORTC Data Direction Register 52
SSPBUF Synchronous Serial Port Receive Buffer/Transmit Register 50
SSPCON1 WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 50
SSPSTAT SMP CKE D/A P S R/W UA BF 50
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the MSSP in SPI mode.
Note 1: These bits are unimplemented in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

17.4 I2C Mode

The MSSP module in I2C mode fully implements all

master and slave functions (including general call

support) and provides interrupts on Start and Stop bits

in hardware to determine a free bus (multi-master

function). The MSSP module implements the standard

mode specifications, as well as 7-bit and 10-bit

addressing.

Two pins are used for data transfer:

• Serial clock (SCL) – RC3/SCK/SCL

• Serial data (SDA) – RC4/SDI/SDA

The user must configure these pins as inputs or outputs

through the TRISC<4:3> bits.

FIGURE 17-7: MSSP BLOCK DIAGRAM

(I2C™ MODE)

17.4.1 REGISTERS

The MSSP module has six registers for I2C operation.

These are:

• MSSP Control Register 1 (SSPCON1)

• MSSP Control Register 2 (SSPCON2)

• MSSP Status Register (SSPSTAT)

• Serial Receive/Transmit Buffer Register

(SSPBUF)

• MSSP Shift Register (SSPSR) – Not directly

accessible

• MSSP Address Register (SSPADD)

SSPCON1, SSPCON2 and SSPSTAT are the control

and status registers in I2C mode operation. The

SSPCON1 and SSPCON2 registers are readable and

writable. The lower 6 bits of the SSPSTAT are read-only.

The upper two bits of the SSPSTAT are read/write.

SSPSR is the shift register used for shifting data in or

out. SSPBUF is the buffer register to which data bytes

are written to or read from.

SSPADD register holds the slave device address

when the SSP is configured in I2C Slave mode. When

the SSP is configured in Master mode, the lower

seven bits of SSPADD act as the Baud Rate

Generator reload value.

In receive operations, SSPSR and SSPBUF together

create a double-buffered receiver. When SSPSR

receives a complete byte, it is transferred to SSPBUF

and the SSPIF interrupt is set.

During transmission, the SSPBUF is not double-

buffered. A write to SSPBUF will write to both SSPBUF

and SSPSR.

Read Write

SSPSR reg

Match Detect

SSPADD reg

Start and

Stop bit Detect

SSPBUF reg

Internal

Data Bus

Addr Match

Set, Reset

S, P bits

(SSPSTAT reg)

RC3/SCK/SCL

RC4/SDI/SDA

Shift

Clock

MSb LSb

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

SMP CKE D/A P(1) S(1) R/W(2,3) UA BF

bit 7 bit 0

bit 7 SMP: Slew Rate Control bit

In Master or Slave mode:

1 = Slew rate control disabled for Standard Speed mode (100 kHz and 1 MHz)

0 = Slew rate control enabled for High-Speed mode (400 kHz)

bit 6 CKE: SMBus Select bit

In Master or Slave mode:

1 = Enable SMBus specific inputs

0 = Disable SMBus specific inputs

bit 5 D/A: Data/Address bit

In Master mode:

Reserved.

In Slave mode:

1 = Indicates that the last byte received or transmitted was data

0 = Indicates that the last byte received or transmitted was address

bit 4 P: Stop bit(1)

1 = Indicates that a Stop bit has been detected last

0 = Stop bit was not detected last

bit 3 S: Start bit(1)

1 = Indicates that a Start bit has been detected last

0 = Start bit was not detected last

bit 2 R/W: Read/Write bit Information (I2C mode only)(2,3)

In Slave mode:

1 = Read

0 = Write

In Master mode:

1 = Transmit is in progress

0 = Transmit is not in progress

bit 1 UA: Update Address bit (10-bit Slave mode only)

1 = Indicates that the user needs to update the address in the SSPADD register

0 = Address does not need to be updated

bit 0 BF: Buffer Full Status bit

In Receive mode:

1 = Receive complete, SSPBUF is full

0 = Receive not complete, SSPBUF is empty

In Transmit mode:

1 = Data transmit in progress (does not include the ACK and Stop bits), SSPBUF is full

0 = Data transmit complete (does not include the ACK and Stop bits), SSPBUF is empty

Note 1: This bit is cleared on Reset and when SSPEN is cleared.

2: This bit holds the R/W bit information following the last address match. This bit is only

valid from the address match to the next Start bit, Stop bit or not ACK bit.

3: ORing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is

in Idle mode.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0

bit 7 bit 0

bit 7 WCOL: Write Collision Detect bit

In Master Transmit mode:

1 = A write to the SSPBUF register was attempted while the I2C conditions were not valid for

a transmission to be started (must be cleared in software)

0 = No collision

In Slave Transmit mode:

1 = The SSPBUF register is written while it is still transmitting the previous word (must be

cleared in software)

0 = No collision

In Receive mode (Master or Slave modes):

This is a “don’t care” bit.

bit 6 SSPOV: Receive Overflow Indicator bit

In Receive mode:

1 = A byte is received while the SSPBUF register is still holding the previous byte (must be

cleared in software)

0 = No overflow

In Transmit mode:

This is a “don’t care” bit in Transmit mode.

bit 5 SSPEN: Synchronous Serial Port Enable bit

1 = Enables the serial port and configures the SDA and SCL pins as the serial port pins

0 = Disables serial port and configures these pins as I/O port pins

Note: When enabled, the SDA and SCL pins must be properly configured as input or

output.

bit 4 CKP: SCK Release Control bit

In Slave mode:

1 = Release clock

0 = Holds clock low (clock stretch), used to ensure data setup time

In Master mode:

Unused in this mode.

bit 3-0 SSPM3:SSPM0: Synchronous Serial Port Mode Select bits

1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled

1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled

1011 = I2C Firmware Controlled Master mode (Slave Idle)

1000 = I2C Master mode, clock = FOSC/(4 * (SSPADD + 1))

0111 = I2C Slave mode, 10-bit address

0110 = I2C Slave mode, 7-bit address

Note: Bit combinations not specifically listed here are either reserved or implemented in

SPI mode only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

GCEN ACKSTAT ACKDT ACKEN(1) RCEN(1) PEN(1) RSEN(1) SEN(1)

bit 7 bit 0

bit 7 GCEN: General Call Enable bit (Slave mode only)

1 = Enable interrupt when a general call address (0000h) is received in the SSPSR

0 = General call address disabled

bit 6 ACKSTAT: Acknowledge Status bit (Master Transmit mode only)

1 = Acknowledge was not received from slave

0 = Acknowledge was received from slave

bit 5 ACKDT: Acknowledge Data bit (Master Receive mode only)

1 = Not Acknowledge

0 = Acknowledge

Note: Value that will be transmitted when the user initiates an Acknowledge sequence at

the end of a receive.

bit 4 ACKEN: Acknowledge Sequence Enable bit (Master Receive mode only)(1)

1 = Initiate Acknowledge sequence on SDA and SCL pins and transmit ACKDT data bit.

Automatically cleared by hardware.

0 = Acknowledge sequence Idle

bit 3 RCEN: Receive Enable bit (Master mode only)(1)

1 = Enables Receive mode for I2C

0 = Receive Idle

bit 2 PEN: Stop Condition Enable bit (Master mode only)(1)

1 = Initiate Stop condition on SDA and SCL pins. Automatically cleared by hardware.

0 = Stop condition Idle

bit 1 RSEN: Repeated Start Condition Enable bit (Master mode only)(1)

1 = Initiate Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware.

0 = Repeated Start condition Idle

bit 0 SEN: Start Condition Enable/Stretch Enable bit(1)

In Master mode:

1 = Initiate Start condition on SDA and SCL pins. Automatically cleared by hardware.

0 = Start condition Idle

In Slave mode:

1 = Clock stretching is enabled for both slave transmit and slave receive (stretch enabled)

0 = Clock stretching is disabled

Note 1: For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is not in the Idle mode,

these bits may not be set (no spooling) and the SSPBUF may not be written (or

writes to the SSPBUF are disabled).

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

17.4.2 OPERATION

The MSSP module functions are enabled by setting

MSSP Enable bit, SSPEN (SSPCON<5>).

The SSPCON1 register allows control of the I2C

operation. Four mode selection bits (SSPCON<3:0>)

allow one of the following I2C modes to be selected:

•I

2C Master mode, clock = (FOSC/4) x (SSPADD + 1)

•I

2C Slave mode (7-bit address)

•I

2C Slave mode (10-bit address)

•I

2C Slave mode (7-bit address) with Start and

Stop bit interrupts enabled

•I

2C Slave mode (10-bit address) with Start and

Stop bit interrupts enabled

•I

2C Firmware Controlled Master mode, slave is

Idle

Selection of any I2C mode with the SSPEN bit set,

forces the SCL and SDA pins to be open-drain,

provided these pins are programmed to inputs by

setting the appropriate TRISC bits. To ensure proper

operation of the module, pull-up resistors must be

provided externally to the SCL and SDA pins.

17.4.3 SLAVE MODE

In Slave mode, the SCL and SDA pins must be config-

ured as inputs (TRISC<4:3> set). The MSSP module

will override the input state with the output data when

required (slave-transmitter).

The I2C Slave mode hardware will always generate an

interrupt on an address match. Through the mode

select bits, the user can also choose to interrupt on

Start and Stop bits

When an address is matched, or the data transfer after

an address match is received, the hardware automati-

cally will generate the Acknowledge (ACK) pulse and

load the SSPBUF register with the received value

currently in the SSPSR register.

Any combination of the following conditions will cause

the MSSP module not to give this ACK pulse:

• The Buffer Full bit, BF (SSPSTAT<0>), was set

before the transfer was received.

• The overflow bit, SSPOV (SSPCON<6>), was set

before the transfer was received.

In this case, the SSPSR register value is not loaded

into the SSPBUF, but bit SSPIF (PIR1<3>) is set. The

BF bit is cleared by reading the SSPBUF register, while

bit SSPOV is cleared through software.

The SCL clock input must have a minimum high and

low for proper operation. The high and low times of the

I2C specification, as well as the requirement of the

MSSP module, are shown in timing parameter 100 and

parameter 101.

17.4.3.1 Addressing

Once the MSSP module has been enabled, it waits for

a Start condition to occur. Following the Start condition,

the 8-bits are shifted into the SSPSR register. All

incoming bits are sampled with the rising edge of the

clock (SCL) line. The value of register SSPSR<7:1> is

compared to the value of the SSPADD register. The

address is compared on the falling edge of the eighth

clock (SCL) pulse. If the addresses match and the BF

and SSPOV bits are clear, the following events occur:

1. The SSPSR register value is loaded into the

SSPBUF register.

2. The Buffer Full bit, BF, is set.

3. An ACK pulse is generated.

4. MSSP Interrupt Flag bit, SSPIF (PIR1<3>), is

set (interrupt is generated, if enabled) on the

falling edge of the ninth SCL pulse.

In 10-bit Address mode, two address bytes need to be

received by the slave. The five Most Significant bits

(MSbs) of the first address byte specify if this is a 10-bit

address. Bit R/W (SSPSTAT<2>) must specify a write so

the slave device will receive the second address byte.

For a 10-bit address, the first byte would equal ‘11110

A9 A8 0’, where ‘A9’ and ‘A8’ are the two MSbs of the

address. The sequence of events for 10-bit address is as

follows, with steps 7 through 9 for the slave-transmitter:

1. Receive first (high) byte of address (bits SSPIF,

BF and UA (SSPSTAT<1>) are set).

2. Update the SSPADD register with second (low)

byte of address (clears bit UA and releases the

SCL line).

3. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

4. Receive second (low) byte of address (bits

SSPIF, BF and UA are set).

5. Update the SSPADD register with the first (high)

byte of address. If match releases SCL line, this

will clear bit UA.

6. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

7. Receive Repeated Start condition.

8. Receive first (high) byte of address (bits SSPIF

and BF are set).

9. Read the SSPBUF register (clears bit BF) and

clear flag bit SSPIF.

PIC18F2585/2680/4585/4680

17.4.3.2 Reception

When the R/W bit of the address byte is clear and an

address match occurs, the R/W bit of the SSPSTAT

the SSPBUF register and the SDA line is held low

(ACK).

When the address byte overflow condition exists, then

the no Acknowledge (ACK) pulse is given. An overflow

condition is defined as either bit BF (SSPSTAT<0>) is

set, or bit SSPOV (SSPCON1<6>) is set.

An MSSP interrupt is generated for each data transfer

byte. Flag bit, SSPIF (PIR1<3>), must be cleared in

software. The SSPSTAT register is used to determine

the status of the byte.

If SEN is enabled (SSPCON2<0> = 1), RC3/SCK/SCL

will be held low (clock stretch) following each data

transfer. The clock must be released by setting bit

CKP (SSPCON<4>). See Section 17.4.4 “Clock

Stretching” for more detail.

17.4.3.3 Transmission

When the R/W bit of the incoming address byte is set

and an address match occurs, the R/W bit of the

SSPSTAT register is set. The received address is

loaded into the SSPBUF register. The ACK pulse will

be sent on the ninth bit and pin RC3/SCK/SCL is held

low regardless of SEN (see Section 17.4.4 “Clock

Stretching” for more detail). By stretching the clock,

the master will be unable to assert another clock pulse

until the slave is done preparing the transmit data. The

transmit data must be loaded into the SSPBUF register

which also loads the SSPSR register. Then pin RC3/

SCK/SCL should be enabled by setting bit, CKP

(SSPCON1<4>). The eight data bits are shifted out on

the falling edge of the SCL input. This ensures that the

SDA signal is valid during the SCL high time

(Figure 17-9).

The ACK pulse from the master-receiver is latched on

the rising edge of the ninth SCL input pulse. If the SDA

line is high (not ACK), then the data transfer is

complete. In this case, when the ACK is latched by the

slave, the slave logic is reset (resets SSPSTAT regis-

ter) and the slave monitors for another occurrence of

the Start bit. If the SDA line was low (ACK), the next

transmit data must be loaded into the SSPBUF register.

Again, pin RC3/SCK/SCL must be enabled by setting

bit CKP.

An MSSP interrupt is generated for each data transfer

byte. The SSPIF bit must be cleared in software and

the SSPSTAT register is used to determine the status

of the byte. The SSPIF bit is set on the falling edge of

the ninth clock pulse.

PIC18F2585/2680/4585/4680

FIGURE 17-8: I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

SSPOV (SSPCON1<6>)

S12345678912345678912345 789 P

A7 A6 A5 A4 A3 A2 A1 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D1 D0

ACK

Receiving Data

ACK

Receiving Data

R/W = 0

ACK

Receiving Address

Cleared in software

SSPBUF is read

Bus master

terminates

transfer

SSPOV is set

because SSPBUF is

still full. ACK is not sent.

(PIR1<3>)

CKP (CKP does not reset to ‘0’ when SEN = 0)

PIC18F2585/2680/4585/4680

FIGURE 17-9: I2C™ SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESS)

SDA

SCL

SSPIF (PIR1<3>)

BF (SSPSTAT<0>)

A6 A5 A4 A3 A2 A1 D6 D5 D4 D3 D2 D1 D0

1 2 3 4 5 6 7 8 2 3 4 5 6 7 8 9

SSPBUF is written in software

Cleared in software

From SSPIF ISR

Data in

sampled

ACK

Transmitting Data

R/W =

ACK

Receiving Address

A7 D7

9 1

D6 D5 D4 D3 D2 D1 D0

2 3 4 5 6 7 8 9

SSPBUF is written in software

Cleared in software

From SSPIF ISR

Transmitting Data

CKP

ACK

CKP is set in software CKP is set in software

SCL held low

while CPU

responds to SSPIF

PIC18F2585/2680/4585/4680

FIGURE 17-10: I2C™ SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

S123456789 123456789 12345 789 P

1 1 1 1 0 A9 A8 A7 A6 A5 A4A3 A2A1 A0 D7 D6D5D4 D3 D1D0

Receive Data Byte

ACK

R/W = 0

ACK

Receive First Byte of Address

Cleared in software

(PIR1<3>)

Cleared in software

Receive Second Byte of Address

Cleared by hardware

when SSPADD is updated

with low byte of address

UA (SSPSTAT<1>)

Clock is held low until

update of SSPADD has

taken place

UA is set indicating that

the SSPADD needs to be

updated

UA is set indicating that

SSPADD needs to be

updated

Cleared by hardware when

SSPADD is updated with high

byte of address

SSPBUF is written with

contents of SSPSR

Dummy read of SSPBUF

to clear BF flag

ACK

CKP

12345 789

D7 D6 D5 D4 D3 D1 D0

Receive Data Byte

Bus master

terminates

transfer

ACK

Cleared in software Cleared in software

SSPOV (SSPCON1<6>)

SSPOV is set

because SSPBUF is

still full. ACK is not sent.

(CKP does not reset to ‘0’ when SEN = 0)

Clock is held low until

update of SSPADD has

taken place

PIC18F2585/2680/4585/4680

FIGURE 17-11: I2C™ SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

S1234 5 6789 1 23 45678 9 12345 7 89 P

1 1 1 1 0 A9A8 A7 A6A5A4A3A2A1 A0 1 1 1 1 0A8

R/W=1

ACK

R/W = 0

ACK

Receive First Byte of Address

Cleared in software

Bus master

terminates

transfer

(PIR1<3>)

Receive Second Byte of Address

Cleared by hardware when

SSPADD is updated with low

byte of address

UA (SSPSTAT<1>)

Clock is held low until

update of SSPADD has

taken place

UA is set indicating that

the SSPADD needs to be

updated

UA is set indicating that

SSPADD needs to be

updated

Cleared by hardware when

SSPADD is updated with high

byte of address.

SSPBUF is written with

contents of SSPSR

Dummy read of SSPBUF

to clear BF flag

Receive First Byte of Address

12345 789

D7 D6 D5 D4 D3 D1

ACK

Transmitting Data Byte

Dummy read of SSPBUF

to clear BF flag

Cleared in software

Write of SSPBUF

initiates transmit

Cleared in software

Completion of

clears BF flag

CKP (SSPCON1<4>)

CKP is set in software

CKP is automatically cleared in hardware, holding SCL low

Clock is held low until

update of SSPADD has

taken place

data transmission

Clock is held low until

CKP is set to ‘1’

BF flag is clear

third address sequence

at the end of the

PIC18F2585/2680/4585/4680

17.4.4 CLOCK STRETCHING

Both 7 and 10-bit Slave modes implement automatic

clock stretching during a transmit sequence.

The SEN bit (SSPCON2<0>) allows clock stretching to

be enabled during receives. Setting SEN will cause

the SCL pin to be held low at the end of each data

receive sequence.

17.4.4.1 Clock Stretching for 7-bit Slave

Receive Mode (SEN = 1)

In 7-bit Slave Receive mode, on the falling edge of the

ninth clock at the end of the ACK sequence if the BF

bit is set, the CKP bit in the SSPCON1 register is

automatically cleared, forcing the SCL output to be

held low. The CKP being cleared to ‘0’ will assert the

SCL line low. The CKP bit must be set in the user’s

ISR before reception is allowed to continue. By holding

the SCL line low, the user has time to service the ISR

and read the contents of the SSPBUF before the

master device can initiate another receive sequence.

This will prevent buffer overruns from occurring (see

Figure 17-13).

17.4.4.2 Clock Stretching for 10-bit Slave

Receive Mode (SEN = 1)

In 10-bit Slave Receive mode during the address

sequence, clock stretching automatically takes place

but CKP is not cleared. During this time, if the UA bit is

set after the ninth clock, clock stretching is initiated.

The UA bit is set after receiving the upper byte of the

10-bit address and following the receive of the second

byte of the 10-bit address with the R/W bit cleared to

‘0’. The release of the clock line occurs upon updating

SSPADD. Clock stretching will occur on each data

receive sequence as described in 7-bit mode.

17.4.4.3 Clock Stretching for 7-bit Slave

Transmit Mode

7-bit Slave Transmit mode implements clock stretching

by clearing the CKP bit after the falling edge of the

ninth clock if the BF bit is clear. This occurs regardless

of the state of the SEN bit.

The user’s ISR must set the CKP bit before transmis-

sion is allowed to continue. By holding the SCL line

low, the user has time to service the ISR and load the

contents of the SSPBUF before the master device can

initiate another transmit sequence (see Figure 17-9).

17.4.4.4 Clock Stretching for 10-bit Slave

Transmit Mode

In 10-bit Slave Transmit mode, clock stretching is

controlled during the first two address sequences by

the state of the UA bit, just as it is in 10-bit Slave

Receive mode. The first two addresses are followed

by a third address sequence which contains the high-

order bits of the 10-bit address and the R/W bit set to

‘1’. After the third address sequence is performed, the

UA bit is not set, the module is now configured in

Transmit mode and clock stretching is controlled by

the BF flag as in 7-bit Slave Transmit mode (see

Figure 17-11).

Note 1: If the user reads the contents of the

SSPBUF before the falling edge of the

ninth clock, thus clearing the BF bit, the

CKP bit will not be cleared and clock

stretching will not occur.

2: The CKP bit can be set in software

regardless of the state of the BF bit. The

user should be careful to clear the BF bit

in the ISR before the next receive

sequence in order to prevent an overflow

condition.

Note: If the user polls the UA bit and clears it by

updating the SSPADD register before the

falling edge of the ninth clock occurs and if

the user hasn’t cleared the BF bit by read-

ing the SSPBUF register before that time,

then the CKP bit will still NOT be asserted

low. Clock stretching on the basis of the

state of the BF bit only occurs during a

data sequence, not an address sequence.

Note 1: If the user loads the contents of SSPBUF,

setting the BF bit before the falling edge of

the ninth clock, the CKP bit will not be

cleared and clock stretching will not occur.

2: The CKP bit can be set in software

regardless of the state of the BF bit.

PIC18F2585/2680/4585/4680

17.4.4.5 Clock Synchronization and

the CKP bit

When the CKP bit is cleared, the SCL output is forced

to ‘0’. However, setting the CKP bit will not assert the

SCL output low until the SCL output is already

sampled low. Therefore, the CKP bit will not assert the

SCL line until an external I2C master device has

already asserted the SCL line. The SCL output will

remain low until the CKP bit is set and all other

devices on the I2C bus have deasserted SCL. This

ensures that a write to the CKP bit will not violate the

minimum high time requirement for SCL (see

Figure 17-12).

FIGURE 17-12: CLOCK SYNCHRONIZATION TIMING

SDA

SCL

DX – 1DX

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

SSPCON

CKP

Master device

deasserts clock

Master device

asserts clock

PIC18F2585/2680/4585/4680

FIGURE 17-13: I2C™ SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

SSPOV (SSPCON1<6>)

S1 234 567 89 1 2 345 67 89 1 2345 7 89 P

A7 A6 A5 A4 A3 A2 A1 D7 D6 D5 D4 D3 D2 D1 D0 D7 D6 D5 D4 D3 D1 D0

ACK

Receiving Data

ACK

Receiving Data

R/W = 0

ACK

Receiving Address

Cleared in software

SSPBUF is read

Bus master

terminates

transfer

SSPOV is set

because SSPBUF is

still full. ACK is not sent.

(PIR1<3>)

CKP

written

to ‘1’ in

If BF is cleared

prior to the falling

edge of the 9th clock,

CKP will not be reset

to ‘0’ and no clock

stretching will occur

software

Clock is held low until

CKP is set to ‘1’

Clock is not held low

because buffer full bit is

clear prior to falling edge

of 9th clock

Clock is not held low

because ACK = 1

BF is set after falling

edge of the 9th clock,

CKP is reset to ‘0’ and

clock stretching occurs

PIC18F2585/2680/4585/4680

FIGURE 17-14: I2C™ SLAVE MODE TIMING SEN = 1 (RECEPTION, 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

S123456789 123456789 12345 789 P

1 1 1 1 0 A9A8 A7 A6 A5 A4A3 A2A1 A0 D7D6D5D4 D3 D1D0

Receive Data Byte

ACK

R/W = 0

ACK

Receive First Byte of Address

Cleared in software

(PIR1<3>)

Cleared in software

Receive Second Byte of Address

Cleared by hardware when

SSPADD is updated with low

byte of address after falling edge

UA (SSPSTAT<1>)

Clock is held low until

update of SSPADD has

taken place

UA is set indicating that

the SSPADD needs to be

updated

UA is set indicating that

SSPADD needs to be

updated

Cleared by hardware when

SSPADD is updated with high

byte of address after falling edge

SSPBUF is written with

contents of SSPSR

Dummy read of SSPBUF

to clear BF flag

ACK

CKP

12345 789

D7 D6 D5 D4 D3 D1 D0

Receive Data Byte

Bus master

terminates

transfer

ACK

Cleared in software Cleared in software

SSPOV (SSPCON1<6>)

CKP written to ‘1’

Note: An update of the SSPADD register before

the falling edge of the ninth clock will have

no effect on UA and UA will remain set.

Note: An update of the SSPADD

edge of the ninth clock will

have no effect on UA and

UA will remain set.

in software

Clock is held low until

update of SSPADD has

taken place

of ninth clock

SSPOV is set

because SSPBUF is

still full. ACK is not sent.

Dummy read of SSPBUF

to clear BF flag

Clock is held low until

CKP is set to ‘1’

Clock is not held low

because ACK = 1

PIC18F2585/2680/4585/4680

17.4.5 GENERAL CALL ADDRESS

SUPPORT

The addressing procedure for the I2C bus is such that

the first byte after the Start condition usually

determines which device will be the slave addressed by

the master. The exception is the general call address

which can address all devices. When this address is

used, all devices should, in theory, respond with an

Acknowledge.

The general call address is one of eight addresses

reserved for specific purposes by the I2C protocol. It

consists of all ‘0’s with R/W = 0.

The general call address is recognized when the

General Call Enable bit, GCEN, is enabled

(SSPCON2<7> set). Following a Start bit detect, 8 bits

are shifted into the SSPSR and the address is

compared against the SSPADD. It is also compared to

the general call address and fixed in hardware.

If the general call address matches, the SSPSR is

transferred to the SSPBUF, the BF flag bit is set (eighth

bit) and on the falling edge of the ninth bit (ACK bit), the

SSPIF interrupt flag bit is set.

When the interrupt is serviced, the source for the

interrupt can be checked by reading the contents of the

SSPBUF. The value can be used to determine if the

address was device specific or a general call address.

In 10-bit mode, the SSPADD is required to be updated

for the second half of the address to match and the UA

bit is set (SSPSTAT<1>). If the general call address is

sampled when the GCEN bit is set, while the slave is

configured in 10-bit Address mode, then the second

half of the address is not necessary, the UA bit will not

be set and the slave will begin receiving data after the

Acknowledge (Figure 17-15).

FIGURE 17-15: SLAVE MODE GENERAL CALL ADDRESS SEQUENCE

(7 OR 10-BIT ADDRESS MODE)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

SSPOV (SSPCON1<6>)

Cleared in software

SSPBUF is read

R/W = 0

ACK

General Call Address

Address is compared to General Call Address

GCEN (SSPCON2<7>)

Receiving Data ACK

1 234 567891 234 56 789

D7 D6 D5 D4 D3 D2 D1 D0

after ACK, set interrupt

‘0’

‘1’

PIC18F2585/2680/4585/4680

17.4.6 MASTER MODE

Master mode is enabled by setting and clearing the

appropriate SSPM bits in SSPCON1 and by setting the

SSPEN bit. In Master mode, the SCL and SDA lines

are manipulated by the MSSP hardware.

Master mode of operation is supported by interrupt

generation on the detection of the Start and Stop

conditions. The Stop (P) and Start (S) bits are cleared

from a Reset or when the MSSP module is disabled.

Control of the I2C bus may be taken when the P bit is

set or the bus is Idle, with both the S and P bits clear.

In Firmware Controlled Master mode, user code

conducts all I2C bus operations based on Start and

Stop bit conditions.

Once Master mode is enabled, the user has six

options.

1. Assert a Start condition on SDA and SCL.

2. Assert a Repeated Start condition on SDA and

SCL.

3. Write to the SSPBUF register initiating

transmission of data/address.

4. Configure the I2C port to receive data.

5. Generate an Acknowledge condition at the end

of a received byte of data.

6. Generate a Stop condition on SDA and SCL.

The following events will cause the SSP Interrupt Flag

bit, SSPIF, to be set (SSP interrupt, if enabled):

• Start condition

• Stop condition

• Data transfer byte transmitted/received

• Acknowledge transmit

• Repeated Start

FIGURE 17-16: MSSP BLOCK DIAGRAM (I2C™ MASTER MODE)

Note: The MSSP module, when configured in

I2C Master mode, does not allow queueing

of events. For instance, the user is not

allowed to initiate a Start condition and

immediately write the SSPBUF register to

initiate transmission before the Start

condition is complete. In this case, the

SSPBUF will not be written to and the

WCOL bit will be set, indicating that a write

to the SSPBUF did not occur.

Read Write

SSPSR

Start bit, Stop bit,

SSPBUF

Internal

Data Bus

Set/Reset, S, P, WCOL (SSPSTAT)

Shift

Clock

MSb LSb

SDA

Acknowledge

Generate

Stop bit Detect

Write Collision Detect

Clock Arbitration

State Counter for

end of XMIT/RCV

SCL

SCL In

Bus Collision

SDA In

Receive Enable

Clock Cntl

Clock Arbitrate/WCOL Detect

(hold off clock source)

SSPADD<6:0>

Baud

Set SSPIF, BCLIF

Reset ACKSTAT, PEN (SSPCON2)

Rate

Generator

SSPM3:SSPM0

Start bit Detect

PIC18F2585/2680/4585/4680

17.4.6.1 I2C Master Mode Operation

The master device generates all of the serial clock

pulses and the Start and Stop conditions. A transfer is

ended with a Stop condition or with a Repeated Start

condition. Since the Repeated Start condition is also

the beginning of the next serial transfer, the I2C bus will

not be released.

In Master Transmitter mode, serial data is output

through SDA, while SCL outputs the serial clock. The

first byte transmitted contains the slave address of the

receiving device (7 bits) and the Read/Write (R/W) bit.

In this case, the R/W bit will be logic ‘0’. Serial data is

transmitted 8 bits at a time. After each byte is transmit-

ted, an Acknowledge bit is received. Start and Stop

conditions are output to indicate the beginning and the

end of a serial transfer.

In Master Receive mode, the first byte transmitted

contains the slave address of the transmitting device

(7 bits) and the R/W bit. In this case, the R/W bit will be

logic ‘1’ Thus, the first byte transmitted is a 7-bit slave

address followed by a ‘1’ to indicate the receive bit.

Serial data is received via SDA, while SCL outputs the

serial clock. Serial data is received 8 bits at a time. After

each byte is received, an Acknowledge bit is transmit-

ted. Start and Stop conditions indicate the beginning

and end of transmission.

The Baud Rate Generator used for the SPI mode

operation is used to set the SCL clock frequency for

either 100 kHz, 400 kHz or 1 MHz I2C operation. See

Section 17.4.7 “Baud Rate” for more detail.

A typical transmit sequence would go as follows:

1. The user generates a Start condition by setting

the Start Enable bit, SEN (SSPCON2<0>).

2. SSPIF is set. The MSSP module will wait the

required start time before any other operation

takes place.

3. The user loads the SSPBUF with the slave

address to transmit.

4. Address is shifted out the SDA pin until all 8 bits

are transmitted.

5. The MSSP Module shifts in the ACK bit from the

slave device and writes its value into the

SSPCON2 register (SSPCON2<6>).

6. The MSSP module generates an interrupt at the

end of the ninth clock cycle by setting the SSPIF

bit.

7. The user loads the SSPBUF with eight bits of

data.

8. Data is shifted out the SDA pin until all 8 bits are

transmitted.

9. The MSSP module shifts in the ACK bit from the

slave device and writes its value into the

SSPCON2 register (SSPCON2<6>).

10. The MSSP module generates an interrupt at the

end of the ninth clock cycle by setting the SSPIF

bit.

11. The user generates a Stop condition by setting

the Stop Enable bit, PEN (SSPCON2<2>).

12. Interrupt is generated once the Stop condition is

complete.

PIC18F2585/2680/4585/4680

17.4.7 BAUD RATE

In I2C Master mode, the Baud Rate Generator (BRG)

reload value is placed in the lower 7 bits of the

SSPADD register (Figure 17-17). When a write occurs

to SSPBUF, the Baud Rate Generator will automatically

begin counting. The BRG counts down to ‘0’ and stops

until another reload has taken place. The BRG count is

decremented twice per instruction cycle (T

CY) on the

Q2 and Q4 clocks. In I2C Master mode, the BRG is

reloaded automatically.

Once the given operation is complete (i.e., transmis-

sion of the last data bit is followed by ACK), the internal

clock will automatically stop counting and the SCL pin

will remain in its last state.

Table 17-3 demonstrates clock rates based on

instruction cycles and the BRG value loaded into

SSPADD.

FIGURE 17-17: BAUD RATE GENERATOR BLOCK DIAGRAM

TABLE 17-3: I2C™ CLOCK RATE W/BRG

SSPM3:SSPM0

BRG Down Counter

CLKO FOSC/4

SSPADD<6:0>

SSPM3:SSPM0

SCL

Reload

Control

Reload

FCY FCY*2 BRG Value FSCL

(2 Rollovers of BRG)

10 MHz 20 MHz 19h 400 kHz(1)

10 MHz 20 MHz 20h 312.5 kHz

10 MHz 20 MHz 64h 100 kHz

4 MHz 8 MHz 0Ah 400 kHz(1)

4 MHz 8 MHz 0Dh 308 kHz

4 MHz 8 MHz 28h 100 kHz

1 MHz 2 MHz 03h 333 kHz(1)

1 MHz 2 MHz 0Ah 100 kHz

1 MHz 2 MHz 00h 1 MHz(1)

Note 1: The I2C™ interface does not conform to the 400 kHz I2C specification (which applies to rates greater than

100 kHz) in all details, but may be used with care where higher rates are required by the application.

PIC18F2585/2680/4585/4680

17.4.7.1 Clock Arbitration

Clock arbitration occurs when the master, during any

receive, transmit or Repeated Start/Stop condition,

deasserts the SCL pin (SCL allowed to float high).

When the SCL pin is allowed to float high, the Baud

Rate Generator (BRG) is suspended from counting

until the SCL pin is actually sampled high. When the

SCL pin is sampled high, the Baud Rate Generator is

reloaded with the contents of SSPADD<6:0> and

begins counting. This ensures that the SCL high time

will always be at least one BRG rollover count in the

event that the clock is held low by an external device

(Figure 17-18).

FIGURE 17-18: BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION

SDA

SCL

SCL deasserted but slave holds

DX – 1DX

BRG

SCL is sampled high, reload takes

place and BRG starts its count

03h 02h 01h 00h (hold off) 03h 02h

Reload

BRG

Value

SCL low (clock arbitration)

SCL allowed to transition high

BRG decrements on

Q2 and Q4 cycles

PIC18F2585/2680/4585/4680

17.4.8 I2C MASTER MODE START

CONDITION TIMING

To initiate a Start condition, the user sets the Start

Enable bit, SEN (SSPCON2<0>). If the SDA and SCL

pins are sampled high, the Baud Rate Generator is

reloaded with the contents of SSPADD<6:0> and starts

its count. If SCL and SDA are both sampled high when

the Baud Rate Generator times out (TBRG), the SDA

pin is driven low. The action of the SDA being driven

low while SCL is high is the Start condition and causes

the S bit (SSPSTAT<3>) to be set. Following this, the

Baud Rate Generator is reloaded with the contents of

SSPADD<6:0> and resumes its count. When the Baud

Rate Generator times out (TBRG), the SEN bit

(SSPCON2<0>) will be automatically cleared by

hardware, the Baud Rate Generator is suspended,

leaving the SDA line held low and the Start condition is

complete.

17.4.8.1 WCOL Status Flag

If the user writes the SSPBUF when a Start sequence

is in progress, the WCOL is set and the contents of the

buffer are unchanged (the write doesn’t occur).

FIGURE 17-19: FIRST START BIT TIMING

Note: If at the beginning of the Start condition,

the SDA and SCL pins are already sam-

pled low, or if during the Start condition, the

SCL line is sampled low before the SDA

line is driven low, a bus collision occurs,

the Bus Collision Interrupt Flag, BCLIF, is

set, the Start condition is aborted and the

I2C module is reset into its Idle state.

Note: Because queueing of events is not

allowed, writing to the lower 5 bits of

SSPCON2 is disabled until the Start

condition is complete.

SDA

SCL

TBRG

1st bit 2nd bit

TBRG

SDA = 1, At completion of Start bit,

SCL = 1

Write to SSPBUF occurs here

TBRG

hardware clears SEN bit

TBRG

Write to SEN bit occurs here Set S bit (SSPSTAT<3>)

and sets SSPIF bit

PIC18F2585/2680/4585/4680

17.4.9 I2C MASTER MODE REPEATED

START CONDITION TIMING

A Repeated Start condition occurs when the RSEN bit

(SSPCON2<1>) is programmed high and the I2C logic

module is in the Idle state. When the RSEN bit is set,

the SCL pin is asserted low. When the SCL pin is

sampled low, the Baud Rate Generator is loaded with

the contents of SSPADD<5:0> and begins counting.

The SDA pin is released (brought high) for one Baud

Rate Generator count (TBRG). When the Baud Rate

Generator times out, if SDA is sampled high, the SCL

pin will be deasserted (brought high). When SCL is

sampled high, the Baud Rate Generator is reloaded

with the contents of SSPADD<6:0> and begins count-

ing. SDA and SCL must be sampled high for one TBRG.

This action is then followed by assertion of the SDA pin

(SDA = 0) for one TBRG while SCL is high. Following

this, the RSEN bit (SSPCON2<1>) will be automatically

cleared and the Baud Rate Generator will not be

reloaded, leaving the SDA pin held low. As soon as a

Start condition is detected on the SDA and SCL pins,

the S bit (SSPSTAT<3>) will be set. The SSPIF bit will

not be set until the Baud Rate Generator has timed out.

Immediately following the SSPIF bit getting set, the user

may write the SSPBUF with the 7-bit address in 7-bit

mode, or the default first address in 10-bit mode. After

the first eight bits are transmitted and an ACK is

received, the user may then transmit an additional eight

bits of address (10-bit mode) or eight bits of data (7-bit

mode).

17.4.9.1 WCOL Status Flag

If the user writes the SSPBUF when a Repeated Start

sequence is in progress, the WCOL is set and the

contents of the buffer are unchanged (the write doesn’t

occur).

FIGURE 17-20: REPEAT START CONDITION WAVEFORM

Note 1: If RSEN is programmed while any other

event is in progress, it will not take effect.

2: A bus collision during the Repeated Start

condition occurs if:

• SDA is sampled low when SCL goes

from low-to-high.

• SCL goes low before SDA is

asserted low. This may indicate that

another master is attempting to

transmit a data ‘1’.

Note: Because queueing of events is not

allowed, writing of the lower 5 bits of

SSPCON2 is disabled until the Repeated

Start condition is complete.

SDA

SCL

Sr = Repeated Start

Write to SSPCON2

Write to SSPBUF occurs here

Falling edge of ninth clock,

end of Xmit

At completion of Start bit,

hardware clears RSEN bit

1st bit

Set S (SSPSTAT<3>)

TBRG

SDA = 1,

SCL (no change).

SCL = 1

occurs here.

TBRG TBRG TBRG

and sets SSPIF

PIC18F2585/2680/4585/4680

17.4.10 I2C MASTER MODE

TRANSMISSION

Transmission of a data byte, a 7-bit address or the

other half of a 10-bit address is accomplished by simply

writing a value to the SSPBUF register. This action will

set the Buffer Full flag bit, BF and allow the Baud Rate

Generator to begin counting and start the next

transmission. Each bit of address/data will be shifted

out onto the SDA pin after the falling edge of SCL is

asserted (see data hold time specification parameter

106). SCL is held low for one Baud Rate Generator

rollover count (TBRG). Data should be valid before SCL

is released high (see data setup time specification

parameter 107). When the SCL pin is released high, it

is held that way for TBRG. The data on the SDA pin

must remain stable for that duration and some hold

time after the next falling edge of SCL. After the eighth

bit is shifted out (the falling edge of the eighth clock),

the BF flag is cleared and the master releases SDA.

This allows the slave device being addressed to

respond with an ACK bit during the ninth bit time if an

address match occurred, or if data was received

properly. The status of ACK is written into the ACKDT

bit on the falling edge of the ninth clock. If the master

receives an Acknowledge, the Acknowledge status bit,

ACKSTAT, is cleared. If not, the bit is set. After the ninth

clock, the SSPIF bit is set and the master clock (Baud

Rate Generator) is suspended until the next data byte

is loaded into the SSPBUF, leaving SCL low and SDA

unchanged (Figure 17-21).

After the write to the SSPBUF, each bit of address will

be shifted out on the falling edge of SCL until all seven

address bits and the R/W bit are completed. On the fall-

ing edge of the eighth clock, the master will deassert

the SDA pin, allowing the slave to respond with an

Acknowledge. On the falling edge of the ninth clock, the

master will sample the SDA pin to see if the address

was recognized by a slave. The status of the ACK bit is

loaded into the ACKSTAT status bit (SSPCON2<6>).

Following the falling edge of the ninth clock transmis-

sion of the address, the SSPIF is set, the BF flag is

cleared and the Baud Rate Generator is turned off until

another write to the SSPBUF takes place, holding SCL

low and allowing SDA to float.

17.4.10.1 BF Status Flag

In Transmit mode, the BF bit (SSPSTAT<0>) is set

when the CPU writes to SSPBUF and is cleared when

all 8 bits are shifted out.

17.4.10.2 WCOL Status Flag

If the user writes the SSPBUF when a transmit is

already in progress (i.e., SSPSR is still shifting out a

data byte), the WCOL is set and the contents of the

buffer are unchanged (the write doesn’t occur).

WCOL must be cleared in software.

17.4.10.3 ACKSTAT Status Flag

In Transmit mode, the ACKSTAT bit (SSPCON2<6>) is

cleared when the slave has sent an Acknowledge

(ACK =0) and is set when the slave does not Acknowl-

edge (ACK = 1). A slave sends an Acknowledge when

it has recognized its address (including a general call),

or when the slave has properly received its data.

17.4.11 I2C MASTER MODE RECEPTION

Master mode reception is enabled by programming the

Receive Enable bit, RCEN (SSPCON2<3>).

The Baud Rate Generator begins counting and on each

rollover, the state of the SCL pin changes (high-to-low/

low-to-high) and data is shifted into the SSPSR. After

the falling edge of the eighth clock, the receive enable

flag is automatically cleared, the contents of the

SSPSR are loaded into the SSPBUF, the BF flag bit is

set, the SSPIF flag bit is set and the Baud Rate

Generator is suspended from counting, holding SCL

low. The MSSP is now in Idle state awaiting the next

command. When the buffer is read by the CPU, the BF

flag bit is automatically cleared. The user can then

send an Acknowledge bit at the end of reception by

setting the Acknowledge sequence enable bit, ACKEN

(SSPCON2<4>).

17.4.11.1 BF Status Flag

In receive operation, the BF bit is set when an address

or data byte is loaded into SSPBUF from SSPSR. It is

cleared when the SSPBUF register is read.

17.4.11.2 SSPOV Status Flag

In receive operation, the SSPOV bit is set when 8 bits

are received into the SSPSR and the BF flag bit is

already set from a previous reception.

17.4.11.3 WCOL Status Flag

If the user writes the SSPBUF when a receive is

already in progress (i.e., SSPSR is still shifting in a data

byte), the WCOL bit is set and the contents of the buffer

are unchanged (the write doesn’t occur).

Note: The MSSP module must be in an Idle state

before the RCEN bit is set or the RCEN bit

will be disregarded.

PIC18F2585/2680/4585/4680

FIGURE 17-21: I2C™ MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESS)

SDA

SCL

SSPIF

BF (SSPSTAT<0>)

SEN

A7 A6 A5 A4 A3 A2 A1 ACK = 0D7 D6 D5 D4 D3 D2 D1 D0

ACK

Transmitting Data or Second Half

R/W = 0Transmit Address to Slave

123456789 123456789 P

Cleared in software service routine

SSPBUF is written in software

from SSP interrupt

After Start condition, SEN cleared by hardware

SSPBUF written with 7-bit address and R/W,

start transmit

SCL held low

while CPU

responds to SSPIF

SEN = 0

of 10-bit Address

Write SSPCON2<0> SEN = 1,

start condition begins From slave, clear ACKSTAT bit SSPCON2<6>

ACKSTAT in

SSPCON2 = 1

Cleared in software

SSPBUF written

PEN

R/W

Cleared in software

PIC18F2585/2680/4585/4680

FIGURE 17-22: I2C™ MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESS)

D3D4

D6D7

A7 A6 A5 A4 A3 A2 A1

SDA

SCL 12

3456789123456789 1234

Bus master

terminates

transfer

ACK

Receiving Data from Slave

D3D4

D6D7

ACK

R/W = 1

Transmit Address to Slave

SSPIF

ACK is not sent

Write to SSPCON2<0> (SEN = 1),

Write to SSPBUF occurs here, ACK from Slave

Master configured as a receiver

by programming SSPCON2<3> (RCEN = 1)

PEN bit = 1

written here

Data shifted in on falling edge of CLK

Cleared in software

start XMIT

SEN = 0

SSPOV

SDA = 0, SCL = 1

while CPU

(SSPSTAT<0>)

ACK

Cleared in software

Set SSPIF interrupt

at end of receive

Set P bit

(SSPSTAT<4>)

and SSPIF

ACK from Master

Set SSPIF at end

Set SSPIF interrupt

at end of Acknowledge

sequence

Set SSPIF interrupt

at end of Acknow-

ledge sequence

of receive

Set ACKEN, start Acknowledge sequence

SDA = ACKDT = 1

RCEN cleared

automatically

RCEN = 1, start

next receive

Write to SSPCON2<4>

to start Acknowledge sequence

SDA = ACKDT (SSPCON2<5>) = 0

RCEN cleared

automatically

responds to SSPIF

ACKEN

begin Start condition

Cleared in software

SDA = ACKDT = 0

Last bit is shifted into SSPSR and

contents are unloaded into SSPBUF

Cleared in

software

SSPOV is set because

SSPBUF is still full

PIC18F2585/2680/4585/4680

17.4.12 ACKNOWLEDGE SEQUENCE

TIMING

An Acknowledge sequence is enabled by setting the

Acknowledge sequence enable bit, ACKEN

(SSPCON2<4>). When this bit is set, the SCL pin is

pulled low and the contents of the Acknowledge data bit

are presented on the SDA pin. If the user wishes to gen-

erate an Acknowledge, then the ACKDT bit should be

cleared. If not, the user should set the ACKDT bit before

starting an Acknowledge sequence. The Baud Rate

Generator then counts for one rollover period (TBRG)

and the SCL pin is deasserted (pulled high). When the

SCL pin is sampled high (clock arbitration), the Baud

Rate Generator counts for TBRG. The SCL pin is then

pulled low. Following this, the ACKEN bit is automatically

cleared, the Baud Rate Generator is turned off and the

MSSP module then goes into Idle mode (Figure 17-23).

17.4.12.1 WCOL Status Flag

If the user writes the SSPBUF when an Acknowledge

sequence is in progress, then WCOL is set and the

contents of the buffer are unchanged (the write doesn’t

occur).

17.4.13 STOP CONDITION TIMING

A Stop bit is asserted on the SDA pin at the end of a

receive/transmit by setting the Stop Sequence Enable

bit, PEN (SSPCON2<2>). At the end of a receive/

transmit, the SCL line is held low after the falling edge

of the ninth clock. When the PEN bit is set, the master

will assert the SDA line low. When the SDA line is

sampled low, the Baud Rate Generator is reloaded and

counts down to ‘0’. When the Baud Rate Generator

times out, the SCL pin will be brought high and one

TBRG (Baud Rate Generator rollover count) later, the

SDA pin will be deasserted. When the SDA pin is

sampled high while SCL is high, the P bit

(SSPSTAT<4>) is set. A TBRG later, the PEN bit is

cleared and the SSPIF bit is set (Figure 17-24).

17.4.13.1 WCOL Status Flag

If the user writes the SSPBUF when a Stop sequence

is in progress, then the WCOL bit is set and the

contents of the buffer are unchanged (the write doesn’t

occur).

FIGURE 17-23: ACKNOWLEDGE SEQUENCE WAVEFORM

FIGURE 17-24: STOP CONDITION RECEIVE OR TRANSMIT MODE

Note: TBRG = one Baud Rate Generator period.

SDA

SCL

Set SSPIF at the

Acknowledge sequence starts here,

write to SSPCON2 ACKEN automatically cleared

Cleared in

TBRG TBRG

end of receive

ACKEN = 1, ACKDT = 0

SSPIF

software Set SSPIF at the end

of Acknowledge sequence

Cleared in

software

ACK

SCL

SDA

SDA asserted low before rising edge of clock

Write to SSPCON2,

set PEN

Falling edge of

SCL = 1 for TBRG, followed by SDA = 1 for TBRG

9th clock

SCL brought high after TBRG

Note: TBRG = one Baud Rate Generator period.

TBRG TBRG

after SDA sampled high. P bit (SSPSTAT<4>) is set.

TBRG

to setup Stop condition

ACK

TBRG

PEN bit (SSPCON2<2>) is cleared by

hardware and the SSPIF bit is set

PIC18F2585/2680/4585/4680

17.4.14 SLEEP OPERATION

While in Sleep mode, the I2C module can receive

addresses or data and when an address match or

complete byte transfer occurs, wake the processor

from Sleep (if the MSSP interrupt is enabled).

17.4.15 EFFECT OF A RESET

A Reset disables the MSSP module and terminates the

current transfer.

17.4.16 MULTI-MASTER MODE

In Multi-Master mode, the interrupt generation on the

detection of the Start and Stop conditions allows the

determination of when the bus is free. The Stop (P) and

Start (S) bits are cleared from a Reset or when the

MSSP module is disabled. Control of the I2C bus may

be taken when the P bit (SSPSTAT<4>) is set, or the

bus is Idle, with both the S and P bits clear. When the

bus is busy, enabling the SSP interrupt will generate

the interrupt when the Stop condition occurs.

In multi-master operation, the SDA line must be

monitored for arbitration to see if the signal level is the

expected output level. This check is performed in

hardware with the result placed in the BCLIF bit.

The states where arbitration can be lost are:

• Address Transfer

• Data Transfer

• A Start Condition

• A Repeated Start Condition

• An Acknowledge Condition

17.4.17 MULTI-MASTER COMMUNICATION,

BUS COLLISION AND BUS

ARBITRATION

Multi-Master mode support is achieved by bus arbitra-

tion. When the master outputs address/data bits onto

the SDA pin, arbitration takes place when the master

outputs a ‘1’ on SDA, by letting SDA float high and

another master asserts a ‘0’. When the SCL pin floats

high, data should be stable. If the expected data on

SDA is a ‘1’ and the data sampled on the SDA pin = 0,

then a bus collision has taken place. The master will set

the Bus Collision Interrupt Flag, BCLIF and reset the

I2C port to its Idle state (Figure 17-25).

If a transmit was in progress when the bus collision

occurred, the transmission is halted, the BF flag is

cleared, the SDA and SCL lines are deasserted and the

SSPBUF can be written to. When the user services the

bus collision Interrupt Service Routine and if the I2C

bus is free, the user can resume communication by

asserting a Start condition.

If a Start, Repeated Start, Stop or Acknowledge

condition was in progress when the bus collision

occurred, the condition is aborted, the SDA and SCL

lines are deasserted and the respective control bits in

the SSPCON2 register are cleared. When the user ser-

vices the bus collision Interrupt Service Routine and if

the I2C bus is free, the user can resume communication

by asserting a Start condition.

The master will continue to monitor the SDA and SCL

pins. If a Stop condition occurs, the SSPIF bit will be set.

A write to the SSPBUF will start the transmission of

data at the first data bit regardless of where the

transmitter left off when the bus collision occurred.

In Multi-Master mode, the interrupt generation on the

detection of Start and Stop conditions allows the determi-

nation of when the bus is free. Control of the I2C bus can

be taken when the P bit is set in the SSPSTAT register,

or the bus is Idle and the S and P bits are cleared.

FIGURE 17-25: BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE

SDA

SCL

BCLIF

SDA released

SDA line pulled low

by another source

Sample SDA. While SCL is high,

data doesn’t match what is driven

Bus collision has occurred.

Set bus collision

interrupt (BCLIF)

by the master.

by master

Data changes

while SCL = 0

PIC18F2585/2680/4585/4680

17.4.17.1 Bus Collision During a

Start Condition

During a Start condition, a bus collision occurs if:

a) SDA or SCL are sampled low at the beginning of

the Start condition (Figure 17-26).

b) SCL is sampled low before SDA is asserted low

(Figure 17-27).

During a Start condition, both the SDA and the SCL

pins are monitored.

If the SDA pin is already low, or the SCL pin is already

low, then all of the following occur:

• the Start condition is aborted,

• the BCLIF flag is set; and

• the MSSP module is reset to its Idle state

(Figure 17-26).

The Start condition begins with the SDA and SCL pins

deasserted. When the SDA pin is sampled high, the

Baud Rate Generator is loaded from SSPADD<6:0>

and counts down to 0. If the SCL pin is sampled low

while SDA is high, a bus collision occurs because it is

assumed that another master is attempting to drive a

data ‘1’ during the Start condition.

If the SDA pin is sampled low during this count, the

BRG is reset and the SDA line is asserted early

(Figure 17-28). If, however, a ‘1’ is sampled on the SDA

pin, the SDA pin is asserted low at the end of the BRG

count. The Baud Rate Generator is then reloaded and

counts down to 0 and during this time, if the SCL pins

are sampled as ‘0’, a bus collision does not occur. At

the end of the BRG count, the SCL pin is asserted low.

FIGURE 17-26: BUS COLLISION DURING START CONDITION (SDA ONLY)

Note: The reason that bus collision is not a factor

during a Start condition is that no two bus

masters can assert a Start condition at the

exact same time. Therefore, one master

will always assert SDA before the other.

This condition does not cause a bus

collision because the two masters must be

allowed to arbitrate the first address

following the Start condition. If the address

is the same, arbitration must be allowed to

continue into the data portion, Repeated

Start or Stop conditions.

SDA

SCL

SEN

SDA sampled low before

SDA goes low before the SEN bit is set.

S bit and SSPIF set because

SSP module reset into Idle state.

SEN cleared automatically because of bus collision.

S bit and SSPIF set because

Set SEN, enable Start

condition if SDA = 1, SCL = 1

SDA = 0, SCL = 1.

BCLIF

SSPIF

SDA = 0, SCL = 1.

SSPIF and BCLIF are

cleared in software

SSPIF and BCLIF are

cleared in software

Set BCLIF,

Start condition. Set BCLIF.

PIC18F2585/2680/4585/4680

FIGURE 17-27: BUS COLLISION DURING START CONDITION (SCL = 0)

FIGURE 17-28: BRG RESET DUE TO SDA ARBITRATION DURING START CONDITION

SDA

SCL

SEN bus collision occurs. Set BCLIF.

SCL = 0 before SDA = 0,

Set SEN, enable Start

sequence if SDA = 1, SCL = 1

TBRG TBRG

SDA = 0, SCL = 1

BCLIF

SSPIF

Interrupt cleared

in software

bus collision occurs. Set BCLIF.

SCL = 0 before BRG time-out,

‘0’‘0’

SDA

SCL

SEN

Set S

Less than TBRG TBRG

SDA = 0, SCL = 1

BCLIF

SSPIF

Interrupts cleared

in software

set SSPIF

SDA = 0, SCL = 1,

SDA pulled low by other master.

Reset BRG and assert SDA.

SCL pulled low after BRG

time-out

Set SSPIF

‘0’

Set SEN, enable START

sequence if SDA = 1, SCL = 1

PIC18F2585/2680/4585/4680

17.4.17.2 Bus Collision During a Repeated

Start Condition

During a Repeated Start condition, a bus collision

occurs if:

a) A low level is sampled on SDA when SCL goes

from low level to high level.

b) SCL goes low before SDA is asserted low,

indicating that another master is attempting to

transmit a data ‘1’.

When the user deasserts SDA and the pin is allowed to

float high, the BRG is loaded with SSPADD<6:0> and

counts down to 0. The SCL pin is then deasserted and

when sampled high, the SDA pin is sampled.

If SDA is low, a bus collision has occurred (i.e., another

master is attempting to transmit a data ‘0’, Figure 17-29).

If SDA is sampled high, the BRG is reloaded and begins

counting. If SDA goes from high to low before the BRG

times out, no bus collision occurs because no two

masters can assert SDA at exactly the same time.

If SCL goes from high to low before the BRG times out

and SDA has not already been asserted, a bus collision

occurs. In this case, another master is attempting to

transmit a data ‘1’ during the Repeated Start condition,

see Figure 17-30.

If, at the end of the BRG time-out, both SCL and SDA

are still high, the SDA pin is driven low and the BRG is

reloaded and begins counting. At the end of the count,

regardless of the status of the SCL pin, the SCL pin is

driven low and the Repeated Start condition is

complete.

FIGURE 17-29: BUS COLLISION DURING A REPEATED START CONDITION (CASE 1)

FIGURE 17-30: BUS COLLISION DURING A REPEATED START CONDITION (CASE 2)

SDA

SCL

RSEN

BCLIF

SSPIF

Sample SDA when SCL goes high.

If SDA = 0, set BCLIF and release SDA and SCL.

Cleared in software

‘0’

SDA

SCL

BCLIF

RSEN

SSPIF

Interrupt cleared

in software

SCL goes low before SDA,

set BCLIF. Release SDA and SCL.

TBRG TBRG

‘0’

PIC18F2585/2680/4585/4680

17.4.17.3 Bus Collision During a Stop

Condition

Bus collision occurs during a Stop condition if:

a) After the SDA pin has been deasserted and

allowed to float high, SDA is sampled low after

the BRG has timed out.

b) After the SCL pin is deasserted, SCL is sampled

low before SDA goes high.

The Stop condition begins with SDA asserted low.

When SDA is sampled low, the SCL pin is allowed to

float. When the pin is sampled high (clock arbitration),

the Baud Rate Generator is loaded with SSPADD<6:0>

and counts down to 0. After the BRG times out, SDA is

sampled. If SDA is sampled low, a bus collision has

occurred. This is due to another master attempting to

drive a data ‘0’ (Figure 17-31). If the SCL pin is

sampled low before SDA is allowed to float high, a bus

collision occurs. This is another case of another master

attempting to drive a data ‘0’ (Figure 17-32).

FIGURE 17-31: BUS COLLISION DURING A STOP CONDITION (CASE 1)

FIGURE 17-32: BUS COLLISION DURING A STOP CONDITION (CASE 2)

SDA

SCL

BCLIF

PEN

SSPIF

TBRG TBRG TBRG

SDA asserted low

SDA sampled

low after TBRG,

set BCLIF

‘0’

SDA

SCL

BCLIF

PEN

SSPIF

TBRG TBRG TBRG

Assert SDA SCL goes low before SDA goes high,

set BCLIF

‘0’

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

18.0 ENHANCED UNIVERSAL

SYNCHRONOUS RECEIVER

TRANSMITTER (EUSART)

The Universal Synchronous Asynchronous Receiver

Transmitter (USART) module is one of the two serial

I/O modules. (USART is also known as a Serial

Communications Interface or SCI.) The USART can be

configured as a full-duplex asynchronous system that

can communicate with peripheral devices, such as

CRT terminals and personal computers. It can also be

configured as a half-duplex synchronous system that

can communicate with peripheral devices, such as A/D

or D/A integrated circuits, serial EEPROMs and so on.

The EUSART module implements additional features,

including automatic baud rate detection and calibra-

tion, automatic wake-up on Sync Break reception and

12-bit Break character transmit. These make it ideally

suited for use in Local Interconnect Network bus (LIN

bus) systems.

The EUSART can be configured in the following

modes:

• Asynchronous (full-duplex) with:

- Auto-Wake-up on character reception

- Auto-Baud calibration

- 12-bit Break character transmission

• Synchronous – Master (half-duplex) with

selectable clock polarity

• Synchronous – Slave (half-duplex) with selectable

clock polarity

The pins of the Enhanced USART are multiplexed with

PORTC. In order to configure RC6/TX/CK and

RC7/RX/DT as a USART:

• bit SPEN (RCSTA<7>) must be set (= 1)

• bit TRISC<7> must be set (= 1)

• bit TRISC<6> must be cleared (= 0) for

Asynchronous and Synchronous Master modes,

or set (= 1) for Synchronous Slave mode

The operation of the Enhanced USART module is

controlled through three registers:

• Transmit Status and Control (TXSTA)

• Receive Status and Control (RCSTA)

• Baud Rate Control (BAUDCON)

These are detailed on the following pages in

respectively.

Note: The EUSART control will automatically

reconfigure the pin from input to output as

needed.

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-1 R/W-0

CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D

bit 7 bit 0

bit 7 CSRC: Clock Source Select bit

Asynchronous mode:

Don’t care.

Synchronous mode:

1 = Master mode (clock generated internally from BRG)

0 = Slave mode (clock from external source)

bit 6 TX9: 9-bit Transmit Enable bit

1 = Selects 9-bit transmission

0 = Selects 8-bit transmission

bit 5 TXEN: Transmit Enable bit

1 = Transmit enabled

0 = Transmit disabled

Note: SREN/CREN overrides TXEN in Sync mode.

bit 4 SYNC: EUSART Mode Select bit

1 = Synchronous mode

0 = Asynchronous mode

bit 3 SENDB: Send Break Character bit

Asynchronous mode:

1 = Send Sync Break on next transmission (cleared by hardware upon completion)

0 = Sync Break transmission completed

Synchronous mode:

Don’t care.

bit 2 BRGH: High Baud Rate Select bit

Asynchronous mode:

1 = High speed

0 = Low speed

Synchronous mode:

Unused in this mode.

bit 1 TRMT: Transmit Shift Register Status bit

1 = TSR empty

0 = TSR full

bit 0 TX9D: 9th bit of Transmit Data

Can be address/data bit or a parity bit.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-0 R-0 R-x

SPEN RX9 SREN CREN ADDEN FERR OERR RX9D

bit 7 bit 0

bit 7 SPEN: Serial Port Enable bit

1 = Serial port enabled (configures RX/DT and TX/CK pins as serial port pins)

0 = Serial port disabled (held in Reset)

bit 6 RX9: 9-bit Receive Enable bit

1 = Selects 9-bit reception

0 = Selects 8-bit reception

bit 5 SREN: Single Receive Enable bit

Asynchronous mode:

Don’t care.

Synchronous mode – Master:

1 = Enables single receive

0 = Disables single receive

This bit is cleared after reception is complete.

Synchronous mode – Slave:

Don’t care.

bit 4 CREN: Continuous Receive Enable bit

Asynchronous mode:

1 = Enables receiver

0 = Disables receiver

Synchronous mode:

1 = Enables continuous receive until enable bit CREN is cleared (CREN overrides SREN)

0 = Disables continuous receive

bit 3 ADDEN: Address Detect Enable bit

Asynchronous mode 9-bit (RX9 = 1):

1 = Enables address detection, enables interrupt and loads the receive buffer when RSR<8>

is set

0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit

Asynchronous mode 9-bit (RX9 = 0):

Don’t care.

bit 2 FERR: Framing Error bit

1 = Framing error (can be updated by reading RCREG register and receiving next valid byte)

0 = No framing error

bit 1 OERR: Overrun Error bit

1 = Overrun error (can be cleared by clearing bit CREN)

0 = No overrun error

bit 0 RX9D: 9th bit of Received Data bit

This can be address/data bit or a parity bit and must be calculated by user firmware.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R-1 U-0 R/W-0 R/W-0 U-0 R/W-0 R/W-0

ABDOVF RCIDL — SCKP BRG16 — WUE ABDEN

bit 7 bit 0

bit 7 ABDOVF: Auto-Baud Acquisition Rollover Status bit

1 = A BRG rollover has occurred during Auto-Baud Rate Detect mode

(must be cleared in software)

0 = No BRG rollover has occurred

bit 6 RCIDL: Receive Operation Idle Status bit

1 = Receive operation is Idle

0 = Receive operation is active

bit 5 Unimplemented: Read as ‘0’

bit 4 SCKP: Synchronous Clock Polarity Select bit

Asynchronous mode:

Unused in this mode.

Synchronous mode:

1 = Idle state for clock (CK) is a high level

0 = Idle state for clock (CK) is a low level

bit 3 BRG16: 16-bit Baud Rate Register Enable bit

1 = 16-bit Baud Rate Generator – SPBRGH and SPBRG

0 = 8-bit Baud Rate Generator – SPBRG only (Compatible mode), SPBRGH value ignored

bit 2 Unimplemented: Read as ‘0’

bit 1 WUE: Wake-up Enable bit

Asynchronous mode:

1 = EUSART will continue to sample the RX pin – interrupt generated on falling edge; bit

cleared in hardware on following rising edge

0 = RX pin not monitored or rising edge detected

Synchronous mode:

Unused in this mode.

bit 0 ABDEN: Auto-Baud Detect Enable bit

Asynchronous mode:

1 = Enable baud rate measurement on the next character. Requires reception of a Sync field

(55h); cleared in hardware upon completion

0 = Baud rate measurement disabled or completed

Synchronous mode:

Unused in this mode.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 231
PIC18F2585/2680/4585/4680
18.1 Baud Rate Generator (BRG)
The BRG is a dedicated 8-bit or 16-bit generator that
supports both the Asynchronous and Synchronous
modes of the EUSART. By default, the BRG operates
in 8-bit mode; setting the BRG16 bit (BAUDCON<3>)
selects 16-bit mode.
The SPBRGH:SPBRG register pair controls the period
of a free running timer. In Asynchronous mode, bits
BRGH (TXSTA<2>) and BRG16 (BAUDCON<3>) also
control the baud rate. In Synchronous mode, BRGH is
ignored. Table 18-1 shows the formula for computation
of the baud rate for different EUSART modes which
only apply in Master mode (internally generated clock).
Given the desired baud rate and FOSC, the nearest
integer value for the SPBRGH:SPBRG registers can be
calculated using the formulas in Table 18-1. From this,
the error in baud rate can be determined. An example
calculation is shown in Example 18-1. Typical baud
rates and error values for the various Asynchronous
modes are shown in Table 18-2. It may be advanta-
geous to use the high baud rate (BRGH = 1) or the
16-bit BRG to reduce the baud rate error, or achieve a
slow baud rate for a fast oscillator frequency.
Writing a new value to the SPBRGH:SPBRG registers
causes the BRG timer to be reset (or cleared). This
ensures the BRG does not wait for a timer overflow
before outputting the new baud rate.
18.1.1 OPERATION IN POWER MANAGED 
MODES
The device clock is used to generate the desired baud
rate. When one of the power managed modes is
entered, the new clock source may be operating at a
different frequency. This may require an adjustment to
the value in the SPBRG register pair.
18.1.2 SAMPLING
The data on the RX pin is sampled three times by a
majority detect circuit to determine if a high or a low
level is present at the RX pin.
TABLE 18-1: BAUD RATE FORMULAS
EXAMPLE 18-1: CALCULATING BAUD RATE ERROR           
TABLE 18-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR      
Configuration Bits BRG/EUSART Mode Baud Rate Formula
SYNC BRG16 BRGH
000 8-bit/Asynchronous FOSC/[64 (n + 1)]
001 8-bit/Asynchronous FOSC/[16 (n + 1)]
010 16-bit/Asynchronous
011 16-bit/Asynchronous
FOSC/[4 (n + 1)]10x 8-bit/Synchronous
11x 16-bit/Synchronous
Legend: x = Don’t care, n = value of SPBRGH:SPBRG register pair
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
BAUDCON ABDOVF RCIDL —SCKP BRG16 —WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the BRG.
For a device wi th FOSC of 16 MHz, de sired baud rate  of 9600, Asynchronous mode,  8-bit B RG:
Desire d Baud Rate =  FOSC/(64 ([SPBRGH:SPBRG] + 1) 
Solving for SPBRGH:SPBRG:
X = ((FOSC/Desired Baud Rate)/64) – 1
= ((160 00 000/9600)/64) – 1 
= [25.042] = 25 
Calculated Baud Rate = 16000000/(64 (25 + 1)) 
= 9615 
Error = (Calculated Baud Rate – Desired Baud Rate) /Desired Ba ud  Rate
= ( 9615 – 9600)/9600 = 0.16% 

PIC18F2585/2680/4585/4680

TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES

BAUD

RATE

(K)

SYNC = 0, BRGH = 0, BRG16 = 0

FOSC = 40.000 MHz FOSC = 20.000 MHz FOSC = 10.000 MHz FOSC = 8.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3————————————

1.2 — — — 1.221 1.73 255 1.202 0.16 129 1201 -0.16 103

2.4 2.441 1.73 255 2.404 0.16 129 2.404 0.16 64 2403 -0.16 51

9.6 9.615 0.16 64 9.766 1.73 31 9.766 1.73 15 9615 -0.16 12

19.2 19.531 1.73 31 19.531 1.73 15 19.531 1.73 7 — — —

57.6 56.818 -1.36 10 62.500 8.51 4 52.083 -9.58 2 — — —

115.2 125.000 8.51 4 104.167 -9.58 2 78.125 -32.18 1 — — —

BAUD

RATE

(K)

SYNC = 0, BRGH = 0, BRG16 = 0

FOSC = 4.000 MHz FOSC = 2.000 MHz FOSC = 1.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 0.300 0.16 207 300 -0.16 103 300 -0.16 51

1.2 1.202 0.16 51 1201 -0.16 25 1201 -0.16 12

2.4 2.404 0.16 25 2403 -0.16 12 — — —

9.6 8.929 -6.99 6 — — — — — —

19.2 20.833 8.51 2 — — — — — —

57.6 62.500 8.51 0 — — — — — —

115.2 62.500 -45.75 0 — — — — — —

BAUD

RATE

(K)

SYNC = 0, BRGH = 1, BRG16 = 0

FOSC = 40.000 MHz FOSC = 20.000 MHz FOSC = 10.000 MHz FOSC = 8.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3————————————

1.2————————————

2.4 — — — — — — 2.441 1.73 255 2403 -0.16 207

9.6 9.766 1.73 255 9.615 0.16 129 9.615 0.16 64 9615 -0.16 51

19.2 19.231 0.16 129 19.231 0.16 64 19.531 1.73 31 19230 -0.16 25

57.6 58.140 0.94 42 56.818 -1.36 21 56.818 -1.36 10 55555 3.55 8

115.2 113.636 -1.36 21 113.636 -1.36 10 125.000 8.51 4 — — —

BAUD

RATE

(K)

SYNC = 0, BRGH = 1, BRG16 = 0

FOSC = 4.000 MHz FOSC = 2.000 MHz FOSC = 1.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 — — — — — — 300 -0.16 207

1.2 1.202 0.16 207 1201 -0.16 103 1201 -0.16 51

2.4 2.404 0.16 103 2403 -0.16 51 2403 -0.16 25

9.6 9.615 0.16 25 9615 -0.16 12 — — —

19.2 19.231 0.16 12 — — — — — —

57.6 62.500 8.51 3 — — — — — —

115.2 125.000 8.51 1 — — — — — —

PIC18F2585/2680/4585/4680

BAUD

RATE

(K)

SYNC = 0, BRGH = 0, BRG16 = 1

FOSC = 40.000 MHz FOSC = 20.000 MHz FOSC = 10.000 MHz FOSC = 8.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 0.300 0.00 8332 0.300 0.02 4165 0.300 0.02 2082 300 -0.04 1665

1.2 1.200 0.02 2082 1.200 -0.03 1041 1.200 -0.03 520 1201 -0.16 415

2.4 2.402 0.06 1040 2.399 -0.03 520 2.404 0.16 259 2403 -0.16 207

9.6 9.615 0.16 259 9.615 0.16 129 9.615 0.16 64 9615 -0.16 51

19.2 19.231 0.16 129 19.231 0.16 64 19.531 1.73 31 19230 -0.16 25

57.6 58.140 0.94 42 56.818 -1.36 21 56.818 -1.36 10 55555 3.55 8

115.2 113.636 -1.36 21 113.636 -1.36 10 125.000 8.51 4 — — —

BAUD

RATE

(K)

SYNC = 0, BRGH = 0, BRG16 = 1

FOSC = 4.000 MHz FOSC = 2.000 MHz FOSC = 1.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 0.300 0.04 832 300 -0.16 415 300 -0.16 207

1.2 1.202 0.16 207 1201 -0.16 103 1201 -0.16 51

2.4 2.404 0.16 103 2403 -0.16 51 2403 -0.16 25

9.6 9.615 0.16 25 9615 -0.16 12 — — —

19.2 19.231 0.16 12 — — — — — —

57.6 62.500 8.51 3 — — — — — —

115.2 125.000 8.51 1 — — — — — —

BAUD

RATE

(K)

SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1

FOSC = 40.000 MHz FOSC = 20.000 MHz FOSC = 10.000 MHz FOSC = 8.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 0.300 0.00 33332 0.300 0.00 16665 0.300 0.00 8332 300 -0.01 6665

1.2 1.200 0.00 8332 1.200 0.02 4165 1.200 0.02 2082 1200 -0.04 1665

2.4 2.400 0.02 4165 2.400 0.02 2082 2.402 0.06 1040 2400 -0.04 832

9.6 9.606 0.06 1040 9.596 -0.03 520 9.615 0.16 259 9615 -0.16 207

19.2 19.193 -0.03 520 19.231 0.16 259 19.231 0.16 129 19230 -0.16 103

57.6 57.803 0.35 172 57.471 -0.22 86 58.140 0.94 42 57142 0.79 34

115.2 114.943 -0.22 86 116.279 0.94 42 113.636 -1.36 21 117647 -2.12 16

BAUD

RATE

(K)

SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1

FOSC = 4.000 MHz FOSC = 2.000 MHz FOSC = 1.000 MHz

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

Actual

Rate

(K)

Error

SPBRG

value

(decimal)

0.3 0.300 0.01 3332 300 -0.04 1665 300 -0.04 832

1.2 1.200 0.04 832 1201 -0.16 415 1201 -0.16 207

2.4 2.404 0.16 415 2403 -0.16 207 2403 -0.16 103

9.6 9.615 0.16 103 9615 -0.16 51 9615 -0.16 25

19.2 19.231 0.16 51 19230 -0.16 25 19230 -0.16 12

57.6 58.824 2.12 16 55555 3.55 8 — — —

115.2 111.111 -3.55 8 — — — — — —

TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED)

PIC18F2585/2680/4585/4680

18.1.3 AUTO-BAUD RATE DETECT

The Enhanced USART module supports the automatic

detection and calibration of baud rate. This feature is

active only in Asynchronous mode and while the WUE

bit is clear.

The automatic baud rate measurement sequence

(Figure 18-1) begins whenever a Start bit is received

and the ABDEN bit is set. The calculation is

self-averaging.

In the Auto-Baud Rate Detect (ABD) mode, the clock to

the BRG is reversed. Rather than the BRG clocking the

incoming RX signal, the RX signal is timing the BRG. In

ABD mode, the internal Baud Rate Generator is used

as a counter to time the bit period of the incoming serial

byte stream.

Once the ABDEN bit is set, the state machine will clear

the BRG and look for a Start bit. The Auto-Baud Rate

Detection must receive a byte with the value 55h

(ASCII “U”, which is also the LIN bus Sync character)

in order to calculate the proper bit rate. The measure-

ment is taken over both a low and a high bit time in

order to minimize any effects caused by asymmetry of

the incoming signal. After a Start bit, the SPBRG

begins counting up, using the preselected clock source

on the first rising edge of RX. After eight bits on the RX

pin or the fifth rising edge, an accumulated value

totalling the proper BRG period is left in the

SPBRGH:SPBRG register pair. Once the 5th edge is

seen (this should correspond to the Stop bit), the

ABDEN bit is automatically cleared.

If a rollover of the BRG occurs (an overflow from FFFFh

to 0000h), the event is trapped by the ABDOVF status

bit (BAUDCON<7>). It is set in hardware by BRG

rollovers and can be set or cleared by the user in

software. ABD mode remains active after rollover

events and the ABDEN bit remains set (Figure 18-2).

While calibrating the baud rate period, the BRG

registers are clocked at 1/8th the preconfigured clock

rate. Note that the BRG clock will be configured by the

BRG16 and BRGH bits. Independent of the BRG16 bit

setting, both the SPBRG and SPBRGH will be used as

a 16-bit counter. This allows the user to verify that no

carry occurred for 8-bit modes by checking for 00h in

the SPBRGH register. Refer to Table 18-4 for counter

clock rates to the BRG.

While the ABD sequence takes place, the EUSART

state machine is held in Idle. The RCIF interrupt is set

once the fifth rising edge on RX is detected. The value

in the RCREG needs to be read to clear the RCIF

interrupt. The contents of RCREG should be discarded.

TABLE 18-4: BRG COUNTER

CLOCK RATES

18.1.3.1 ABD and EUSART Transmission

Since the BRG clock is reversed during ABD acquisi-

tion, the EUSART transmitter cannot be used during

ABD. This means that whenever the ABDEN bit is set,

TXREG cannot be written to. Users should also ensure

that ABDEN does not become set during a transmit

sequence. Failing to do this may result in unpredictable

EUSART operation.

Note 1: If the WUE bit is set with the ABDEN bit,

Auto-Baud Rate Detection will occur on

the byte

following

the Break character.

2: It is up to the user to determine that the

incoming character baud rate is within the

range of the selected BRG clock source.

Some combinations of oscillator

frequency and EUSART baud rates are

not possible due to bit error rates. Overall

system timing and communication baud

rates must be taken into consideration

when using the Auto-Baud Rate

Detection feature.

BRG16 BRGH BRG Counter Clock

00 FOSC/512

01 FOSC/128

10 FOSC/128

11 FOSC/32

Note: During the ABD sequence, SPBRG and

SPBRGH are both used as a 16-bit counter,

independent of the BRG16 setting.

PIC18F2585/2680/4585/4680

FIGURE 18-1: AUTOMATIC BAUD RATE CALCULATION

FIGURE 18-2: BRG OVERFLOW SEQUENCE

BRG Value

RX pin

ABDEN bit

RCIF bit

Bit 0 Bit 1

(Interrupt)

Read

RCREG

BRG Clock

Start

Auto-Cleared

Set by User

XXXXh 0000h

Edge #1

Bit 2 Bit 3

Edge #2

Bit 4 Bit 5

Edge #3

Bit 6 Bit 7

Edge #4

Stop Bit

Edge #5

001Ch

Note: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0.

SPBRG XXXXh 1Ch

SPBRGH XXXXh 00h

Start Bit 0

XXXXh 0000h 0000h

FFFFh

BRG Clock

ABDEN bit

RX pin

ABDOVF bit

BRG Value

PIC18F2585/2680/4585/4680

18.2 EUSART Asynchronous Mode

The Asynchronous mode of operation is selected by

clearing the SYNC bit (TXSTA<4>). In this mode, the

EUSART uses standard Non-Return-to-Zero (NRZ)

format (one Start bit, eight or nine data bits and one

Stop bit). The most common data format is 8 bits. An

on-chip dedicated 8-bit/16-bit Baud Rate Generator

can be used to derive standard baud rate frequencies

from the oscillator.

The EUSART transmits and receives the LSb first. The

EUSART’s transmitter and receiver are functionally

independent but use the same data format and baud

rate. The Baud Rate Generator produces a clock, either

x16 or x64 of the bit shift rate depending on the BRGH

and BRG16 bits (TXSTA<2> and BAUDCON<3>). Parity

is not supported by the hardware, but can be

implemented in software and stored as the 9th data bit.

When operating in Asynchronous mode, the EUSART

module consists of the following important elements:

• Baud Rate Generator

• Sampling Circuit

• Asynchronous Transmitter

• Asynchronous Receiver

• Auto-Wake-up on Sync Break Character

• 12-bit Break Character Transmit

• Auto-Baud Rate Detection

18.2.1 EUSART ASYNCHRONOUS

TRANSMITTER

The EUSART transmitter block diagram is shown in

Figure 18-3. The heart of the transmitter is the Transmit

(Serial) Shift Register (TSR). The Shift register obtains

its data from the Read/Write Transmit Buffer register,

TXREG. The TXREG register is loaded with data in

software. The TSR register is not loaded until the Stop

bit has been transmitted from the previous load. As

soon as the Stop bit is transmitted, the TSR is loaded

with new data from the TXREG register (if available).

Once the TXREG register transfers the data to the TSR

CY), the TXREG register is empty

and the TXIF flag bit (PIR1<4>) is set. This interrupt can

be enabled or disabled by setting or clearing the interrupt

enable bit, TXIE (PIE1<4>). TXIF will be set regardless of

the state of TXIE; it cannot be cleared in software. TXIF

is also not cleared immediately upon loading TXREG, but

becomes valid in the second instruction cycle following

the load instruction. Polling TXIF immediately following a

load of TXREG will return invalid results.

While TXIF indicates the status of the TXREG register,

another bit, TRMT (TXSTA<1>), shows the status of

the TSR register. TRMT is a read-only bit which is set

when the TSR register is empty. No interrupt logic is

tied to this bit so the user has to poll this bit in order to

determine if the TSR register is empty.

To set up an Asynchronous Transmission:

1. Initialize the SPBRGH:SPBRG registers for the

appropriate baud rate. Set or clear the BRGH

and BRG16 bits, as required, to achieve the

desired baud rate.

2. Enable the asynchronous serial port by clearing

bit SYNC and setting bit SPEN.

3. If interrupts are desired, set enable bit TXIE.

4. If 9-bit transmission is desired, set transmit bit

TX9. Can be used as address/data bit.

5. Enable the transmission by setting bit TXEN

which will also set bit TXIF.

6. If 9-bit transmission is selected, the ninth bit

should be loaded in bit TX9D.

7. Load data to the TXREG register (starts

transmission).

8. If using interrupts, ensure that the GIE and PEIE

bits in the INTCON register (INTCON<7:6>) are

set.

FIGURE 18-3: EUSART TRANSMIT BLOCK DIAGRAM

Note 1: The TSR register is not mapped in data

memory so it is not available to the user.

2: Flag bit TXIF is set when enable bit TXEN

is set.

TXIF

TXIE

Interrupt

TXEN Baud Rate CLK

SPBRG

Baud Rate Generator

MSb LSb

Data Bus

TXREG Register

TSR Register

(8) 0

TX9

TRMT SPEN

TX pin

Pin Buffer

and Control

• • •

SPBRGH

BRG16

TX9D

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 237
PIC18F2585/2680/4585/4680
FIGURE 18-4: ASYNCHRONOUS TRANSMISSION       
FIGURE 18-5: ASYNCHRONOUS TRANSMISSION (BACK TO BACK)        
TABLE 18-5: REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION       
Word 1
Word 1
Transmit Shift Reg
Start bit bit 0 bit 1 bit 7/8
Write to TXREG
BRG Output
(Shift Clock)
TX
TXIF bit
(Transmit Buffer
Reg. Empty Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
1 TCY
 (pin)
Word 1
Stop bit
Transmit Shift Reg.
Write to TXREG
BRG Output
(Shift Clock)
TX
TXIF bit
(Interrupt Reg. Flag)
TRMT bit
(Transmit Shift
Reg. Empty Flag)
Word 1 Word 2
Word 1 Word 2
Stop bit Start bit
Transmit Shift Reg.
Word 1 Word 2
bit 0 bit 1 bit 7/8 bit 0
Note: This timing diagram shows two consecutive transmissions.
1 TCY
1 TCY
(pin) Start bit
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
TXREG EUSART Transmit Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL —SCKP BRG16 —WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous transmission.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

18.2.2 EUSART ASYNCHRONOUS

RECEIVER

The receiver block diagram is shown in Figure 18-6.

The data is received on the RX pin and drives the data

recovery block. The data recovery block is actually a

high-speed shifter operating at x16 times the baud rate,

whereas the main receive serial shifter operates at the

bit rate or at FOSC. This mode would typically be used

in RS-232 systems.

To set up an Asynchronous Reception:

1. Initialize the SPBRGH:SPBRG registers for the

appropriate baud rate. Set or clear the BRGH

and BRG16 bits, as required, to achieve the

desired baud rate.

2. Enable the asynchronous serial port by clearing

bit SYNC and setting bit SPEN.

3. If interrupts are desired, set enable bit RCIE.

4. If 9-bit reception is desired, set bit RX9.

5. Enable the reception by setting bit CREN.

6. Flag bit RCIF will be set when reception is

complete and an interrupt will be generated if

enable bit RCIE was set.

7. Read the RCSTA register to get the 9th bit (if

enabled) and determine if any error occurred

during reception.

8. Read the 8-bit received data by reading the

RCREG register.

9. If any error occurred, clear the error by clearing

enable bit CREN.

10. If using interrupts, ensure that the GIE and PEIE

bits in the INTCON register (INTCON<7:6>) are

set.

18.2.3 SETTING UP 9-BIT MODE WITH

ADDRESS DETECT

This mode would typically be used in RS-485 systems.

To set up an Asynchronous Reception with Address

Detect Enable:

1. Initialize the SPBRGH:SPBRG registers for the

appropriate baud rate. Set or clear the BRGH

and BRG16 bits, as required, to achieve the

desired baud rate.

2. Enable the asynchronous serial port by clearing

the SYNC bit and setting the SPEN bit.

3. If interrupts are required, set the RCEN bit and

select the desired priority level with the RCIP bit.

4. Set the RX9 bit to enable 9-bit reception.

5. Set the ADDEN bit to enable address detect.

6. Enable reception by setting the CREN bit.

7. The RCIF bit will be set when reception is

complete. The interrupt will be Acknowledged if

the RCIE and GIE bits are set.

8. Read the RCSTA register to determine if any

error occurred during reception, as well as read

bit 9 of data (if applicable).

9. Read RCREG to determine if the device is being

addressed.

10. If any error occurred, clear the CREN bit.

11. If the device has been addressed, clear the

ADDEN bit to allow all received data into the

receive buffer and interrupt the CPU.

FIGURE 18-6: EUSART RECEIVE BLOCK DIAGRAM

x64 Baud Rate CLK

Baud Rate Generator

Pin Buffer

and Control

SPEN

Data

Recovery

CREN OERR FERR

RSR Register

MSb LSb

RX9D RCREG Register

FIFO

Interrupt RCIF

RCIE

Data Bus

÷ 64

÷ 16

Stop Start

(8) 7 1 0

RX9

• • •

SPBRGSPBRGH

BRG16

÷ 4

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 239
PIC18F2585/2680/4585/4680
FIGURE 18-7: ASYNCHRONOUS RECEPTION          
TABLE 18-6: REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION
Start
bit bit 7/8
bit 1bit 0 bit 7/8 bit 0
Stop
bit
Start
bit
Start
bit
bit 7/8 Stop
bit
RX (pin)
Rcv Buffer Reg
Rcv Shift Reg
Read Rcv
Buffer Reg
RCREG
RCIF
(Interrupt Flag)
OERR bit
CREN
Word 1
RCREG
Word 2
RCREG
Stop
bit
Note: This timing diagram shows three words appearing on the RX input.   The RCREG (receive buffer) is read after the third word
causing the OERR (overrun) bit to be set.
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
RCREG EUSART Receive Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL —SCKP BRG16 — WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented locations read as ‘0’. Shaded cells are not used for asynchronous reception.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

18.2.4 AUTO-WAKE-UP ON SYNC BREAK

CHARACTER

During Sleep mode, all clocks to the EUSART are

suspended. Because of this, the Baud Rate Generator

is inactive and a proper byte reception cannot be

performed. The auto-wake-up feature allows the

controller to wake-up due to activity on the RX/DT line

while the EUSART is operating in Asynchronous mode.

The auto-wake-up feature is enabled by setting the

WUE bit (BAUDCON<1>). Once set, the typical receive

sequence on RX/DT is disabled and the EUSART

remains in an Idle state, monitoring for a wake-up event

independent of the CPU mode. A wake-up event

consists of a high-to-low transition on the RX/DT line.

(This coincides with the start of a Sync Break or a

Wake-up Signal character for the LIN protocol.)

Following a wake-up event, the module generates an

RCIF interrupt. The interrupt is generated synchro-

nously to the Q clocks in normal operating modes

(Figure 18-8) and asynchronously, if the device is in

Sleep mode (Figure 18-9). The interrupt condition is

cleared by reading the RCREG register.

The WUE bit is automatically cleared once a low-to-high

transition is observed on the RX line following the

wake-up event. At this point, the EUSART module is in

Idle mode and returns to normal operation. This signals

to the user that the Sync Break event is over.

18.2.4.1 Special Considerations Using

Auto-Wake-up

Since auto-wake-up functions by sensing rising edge

transitions on RX/DT, information with any state

changes before the Stop bit may signal a false

end-of-character and cause data or framing errors. To

work properly, therefore, the initial character in the trans-

mission must be all ‘0’s. This can be 00h (8 bytes) for

standard RS-232 devices or 000h (12 bits) for LIN bus.

Oscillator start-up time must also be considered,

especially in applications using oscillators with longer

start-up intervals (i.e., XT or HS mode). The Sync

Break (or Wake-up Signal) character must be of

sufficient length and be followed by a sufficient interval

to allow enough time for the selected oscillator to start

and provide proper initialization of the EUSART.

18.2.4.2 Special Considerations Using

the WUE Bit

The timing of WUE and RCIF events may cause some

confusion when it comes to determining the validity of

received data. As noted, setting the WUE bit places the

EUSART in an Idle mode. The wake-up event causes

a receive interrupt by setting the RCIF bit. The WUE bit

is cleared after this when a rising edge is seen on

RX/DT. The interrupt condition is then cleared by

reading the RCREG register. Ordinarily, the data in

RCREG will be dummy data and should be discarded.

The fact that the WUE bit has been cleared (or is still

set) and the RCIF flag is set should not be used as an

indicator of the integrity of the data in RCREG. Users

should consider implementing a parallel method in

firmware to verify received data integrity.

To assure that no actual data is lost, check the RCIDL

bit to verify that a receive operation is not in process. If

a receive operation is not occurring, the WUE bit may

then be set just prior to entering the Sleep mode.

FIGURE 18-8: AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION

FIGURE 18-9: AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

OSC1

WUE bit(1)

RX/DT Line

RCIF

Note 1: The EUSART remains in Idle while the WUE bit is set.

Bit set by user Auto-Cleared

Cleared due to user read of RCREG

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

OSC1

WUE bit(2)

RX/DT Line

RCIF

SLEEP Command Executed

Note 1: If the wake-up event requires long oscillator warm-up time, the auto-clear of the WUE bit can occur while the

stposc

signal is still active.

This sequence should not depend on the presence of Q clocks.

2: The EUSART remains in Idle while the WUE bit is set.

Sleep Ends

Auto-Cleared

Note 1

Cleared due to user read of RCREG

Bit set by user

PIC18F2585/2680/4585/4680

18.2.5 BREAK CHARACTER SEQUENCE

The Enhanced EUSART module has the capability of

sending the special Break character sequences that

are required by the LIN bus standard. The Break char-

acter transmit consists of a Start bit, followed by twelve

‘0’ bits and a Stop bit. The frame Break character is

sent whenever the SENDB and TXEN bits (TXSTA<3>

and TXSTA<5>) are set while the Transmit Shift

written to TXREG will be ignored and all ‘0’s will be

transmitted.

The SENDB bit is automatically reset by hardware after

the corresponding Stop bit is sent. This allows the user

to preload the transmit FIFO with the next transmit byte

following the Break character (typically, the Sync

character in the LIN specification).

Note that the data value written to the TXREG for the

Break character is ignored. The write simply serves the

purpose of initiating the proper sequence.

The TRMT bit indicates when the transmit operation is

active or Idle, just as it does during normal transmis-

sion. See Figure 18-10 for the timing of the Break

character sequence.

18.2.5.1 Break and Sync Transmit Sequence

The following sequence will send a message frame

header made up of a Break, followed by an Auto-Baud

Sync byte. This sequence is typical of a LIN bus

master.

1. Configure the EUSART for the desired mode.

2. Set the TXEN and SENDB bits to set up the

Break character.

3. Load the TXREG with a dummy character to

initiate transmission (the value is ignored).

4. Write ‘55h’ to TXREG to load the Sync character

into the transmit FIFO buffer.

5. After the Break has been sent, the SENDB bit is

reset by hardware. The Sync character now

transmits in the preconfigured mode.

When the TXREG becomes empty, as indicated by the

TXIF, the next data byte can be written to TXREG.

18.2.6 RECEIVING A BREAK CHARACTER

The Enhanced USART module can receive a Break

character in two ways.

The first method forces configuration of the baud rate

at a frequency of 9/13 the typical speed. This allows for

the Stop bit transition to be at the correct sampling

location (13 bits for Break versus Start bit and 8 data

bits for typical data).

The second method uses the auto-wake-up feature

described in Section 18.2.4 “Auto-Wake-up on Sync

Break Character”. By enabling this feature, the

EUSART will sample the next two transitions on RX/DT,

cause an RCIF interrupt and receive the next data byte

followed by another interrupt.

Note that following a Break character, the user will

typically want to enable the Auto-Baud Rate Detect

feature. For both methods, the user can set the ABD bit

once the TXIF interrupt is observed.

FIGURE 18-10: SEND BREAK CHARACTER SEQUENCE

Write to TXREG

BRG Output

(Shift Clock)

Start Bit Bit 0 Bit 1 Bit 11 Stop Bit

Break

TXIF bit

(Transmit Buffer

Reg. Empty Flag)

TX (pin)

TRMT bit

(Transmit Shift

Reg. Empty Flag)

SENDB

(Transmit Shift

Reg. Empty Flag)

SENDB sampled here Auto-Cleared

Dummy Write

PIC18F2585/2680/4585/4680

18.3 EUSART Synchronous

Master Mode

The Synchronous Master mode is entered by setting

the CSRC bit (TXSTA<7>). In this mode, the data is

transmitted in a half-duplex manner (i.e., transmission

and reception do not occur at the same time). When

transmitting data, the reception is inhibited and vice

versa. Synchronous mode is entered by setting bit

SYNC (TXSTA<4>). In addition, enable bit SPEN

(RCSTA<7>) is set in order to configure the TX and RX

pins to CK (clock) and DT (data) lines, respectively.

The Master mode indicates that the processor trans-

mits the master clock on the CK line. Clock polarity is

selected with the SCKP bit (BAUDCON<4>); setting

SCKP sets the Idle state on CK as high, while clearing

the bit sets the Idle state as low. This option is provided

to support Microwire devices with this module.

18.3.1 EUSART SYNCHRONOUS MASTER

TRANSMISSION

The EUSART transmitter block diagram is shown in

Figure 18-3. The heart of the transmitter is the Transmit

(Serial) Shift Register (TSR). The Shift register obtains

its data from the Read/Write Transmit Buffer register,

TXREG. The TXREG register is loaded with data in

software. The TSR register is not loaded until the last

bit has been transmitted from the previous load. As

soon as the last bit is transmitted, the TSR is loaded

with new data from the TXREG (if available).

Once the TXREG register transfers the data to the TSR

CYCLE), the TXREG is empty

and the TXIF flag bit (PIR1<4>) is set. The interrupt can

be enabled or disabled by setting or clearing the inter-

rupt enable bit, TXIE (PIE1<4>). TXIF is set regardless

of the state of enable bit TXIE; it cannot be cleared in

software. It will reset only when new data is loaded into

the TXREG register.

While flag bit TXIF indicates the status of the TXREG

status of the TSR register. TRMT is a read-only bit which

is set when the TSR is empty. No interrupt logic is tied to

this bit so the user has to poll this bit in order to

determine if the TSR register is empty. The TSR is not

mapped in data memory so it is not available to the user.

To set up a Synchronous Master Transmission:

1. Initialize the SPBRGH:SPBRG registers for the

appropriate baud rate. Set or clear the BRG16

bit, as required, to achieve the desired baud

rate.

2. Enable the synchronous master serial port by

setting bits SYNC SPEN and CSRC.

3. If interrupts are desired, set enable bit TXIE.

4. If 9-bit transmission is desired, set bit TX9.

5. Enable the transmission by setting bit TXEN.

6. If 9-bit transmission is selected, the ninth bit

should be loaded in bit TX9D.

7. Start transmission by loading data to the TXREG

8. If using interrupts, ensure that the GIE and PEIE

bits in the INTCON register (INTCON<7:6>) are

set.

FIGURE 18-11: SYNCHRONOUS TRANSMISSION

bit 0 bit 1 bit 7

Word 1

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

bit 2 bit 0 bit 1 bit 7

RC7/RX/DT

RC6/TX/CK pin

Write to

TXREG Reg

TXIF bit

(Interrupt Flag)

TXEN bit ‘1’ ‘1’

Word 2

TRMT bit

Write Word 1 Write Word 2

Note: Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words.

RC6/TX/CK pin

(SCKP = 0)

(SCKP = 1)

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 243
PIC18F2585/2680/4585/4680
FIGURE 18-12: SYNCHRONOUS TRANSMISSION (THROUGH TXEN)       
TABLE 18-7: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION       
RC7/RX/DT pin
RC6/TX/CK pin
Write to
TXREG reg
TXIF bit
TRMT bit
bit 0 bit 1 bit 2 bit 6 bit 7
TXEN bit
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
TXREG EUSART Transmit Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL —SCKPBRG16—WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master transmission.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680
DS39625C-page 244 Preliminary © 2007 Microchip Technology Inc.
18.3.2 EUSART SYNCHRONOUS 
MASTER RECEPTION
Once Synchronous mode is selected, reception is
enabled by setting either the Single Receive Enable bit,
SREN (RCSTA<5>), or the Continuous Receive
Enable bit, CREN (RCSTA<4>). Data is sampled on the
RX pin on the falling edge of the clock.
If enable bit SREN is set, only a single word is received.
If enable bit CREN is set, the reception is continuous
until CREN is cleared. If both bits are set, then CREN
takes precedence.
To set up a Synchronous Master Reception:
1. Initialize the SPBRGH:SPBRG registers for the
appropriate baud rate. Set or clear the BRG16
bit, as required, to achieve the desired baud rate.
2. Enable the synchronous master serial port by
setting bits SYNC, SPEN and CSRC.
3. Ensure bits CREN and SREN are clear.
4. If interrupts are desired, set enable bit RCIE.
5. If 9-bit reception is desired, set bit RX9.
6. If a single reception is required, set bit SREN.
For continuous reception, set bit CREN.
7. Interrupt flag bit RCIF will be set when reception
is complete and an interrupt will be generated if
the enable bit RCIE was set.
8. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
9. Read the 8-bit received data by reading the
RCREG register.
10. If any error occurred, clear the error by clearing
bit CREN.
11. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
FIGURE 18-13: SYNCHRONOUS RECEPTION (MASTER MODE, SREN)       
TABLE 18-8: REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION       
NameBit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0
Reset 
Values on 
page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
RCREG EUSART Receive Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL — SCKP BRG16 —WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous master reception.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.
CREN bit
RC7/RX/DT
RC7/TX/CK pin
Write to
bit SREN
SREN bit
RCIF bit
(Interrupt)
Read
RXREG
Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4Q2 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4
‘
0
’
bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7
‘
0
’
Q1 Q2 Q3 Q4
Note: Timing diagram demonstrates Sync Master mode with bit SREN = 1 and bit BRGH = 0.
RC7/TX/CK pin
pin
(SCKP = 0)
(SCKP = 1)

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 245
PIC18F2585/2680/4585/4680
18.4 EUSART Synchronous 
Slave Mode
Synchronous Slave mode is entered by clearing bit,
CSRC (TXSTA<7>). This mode differs from the
Synchronous Master mode in that the shift clock is sup-
plied externally at the CK pin (instead of being supplied
internally in Master mode). This allows the device to
transfer or receive data while in any low-power mode. 
18.4.1 EUSART SYNCHRONOUS 
SLAVE TRANSMIT
The operation of the Synchronous Master and Slave
modes are identical, except in the case of the Sleep
mode.
If two words are written to the TXREG and then the
SLEEP instruction is executed, the following will occur:
a) The first word will immediately transfer to the
TSR register and transmit. 
b) The second word will remain in the TXREG
register. 
c) Flag bit TXIF will not be set. 
d) When the first word has been shifted out of TSR,
the TXREG register will transfer the second
word to the TSR and flag bit TXIF will now be
set. 
e) If enable bit TXIE is set, the interrupt will wake the
chip from Sleep. If the global interrupt is enabled,
the program will branch to the interrupt vector.
To set up a Synchronous Slave Transmission:
1. Enable the synchronous slave serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
2. Clear bits CREN and SREN.
3. If interrupts are desired, set enable bit TXIE.
4. If 9-bit transmission is desired, set bit TX9.
5. Enable the transmission by setting enable bit
TXEN.
6. If 9-bit transmission is selected, the ninth bit
should be loaded in bit TX9D.
7. Start transmission by loading data to the
TXREGx register.
8. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
TABLE 18-9: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION       
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
TXREG EUSART Transmit Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL — SCKP BRG16 —WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave transmission.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680
DS39625C-page 246 Preliminary © 2007 Microchip Technology Inc.
18.4.2 EUSART SYNCHRONOUS SLAVE 
RECEPTION
The operation of the Synchronous Master and Slave
modes is identical, except in the case of Sleep or any
Idle mode and bit SREN, which is a “don’t care” in
Slave mode.
If receive is enabled by setting the CREN bit prior to
entering Sleep or any Idle mode, then a word may be
received while in this low-power mode. Once the word
is received, the RSR register will transfer the data to the
RCREG register; if the RCIE enable bit is set, the inter-
rupt generated will wake the chip from the low-power
mode. If the global interrupt is enabled, the program will
branch to the interrupt vector.
To set up a Synchronous Slave Reception:
1. Enable the synchronous master serial port by
setting bits SYNC and SPEN and clearing bit
CSRC.
2. If interrupts are desired, set enable bit RCIE.
3. If 9-bit reception is desired, set bit RX9.
4. To enable reception, set enable bit CREN.
5. Flag bit RCIF will be set when reception is
complete. An interrupt will be generated if
enable bit RCIE was set.
6. Read the RCSTA register to get the 9th bit (if
enabled) and determine if any error occurred
during reception.
7. Read the 8-bit received data by reading the
RCREG register.
8. If any error occurred, clear the error by clearing
bit CREN.
9. If using interrupts, ensure that the GIE and PEIE
bits in the INTCON register (INTCON<7:6>) are
set.
TABLE 18-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION      
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
RCSTA SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51
RCREG EUSART Receive Register 51
TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51
BAUDCON ABDOVF RCIDL —SCKPBRG16—WUE ABDEN 51
SPBRGH EUSART Baud Rate Generator Register High Byte 51
SPBRG EUSART Baud Rate Generator Register Low Byte 51
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for synchronous slave reception.
Note 1: Reserved in PIC18F2X8X devices; always maintain these bits clear.

PIC18F2585/2680/4585/4680

19.0 10-BIT ANALOG-TO-DIGITAL

CONVERTER (A/D) MODULE

The Analog-to-Digital (A/D) converter module has

8 inputs for the PIC18F2X8X devices and 11 for the

PIC18F4X8X devices. This module allows conversion

of an analog input signal to a corresponding 10-bit

digital number.

The module has five registers:

• A/D Result High Register (ADRESH)

• A/D Result Low Register (ADRESL)

• A/D Control Register 0 (ADCON0)

• A/D Control Register 1 (ADCON1)

• A/D Control Register 2 (ADCON2)

The ADCON0 register, shown in Register 19-1, controls

the operation of the A/D module. The ADCON1 register,

shown in Register 19-2, configures the functions of the

port pins. The ADCON2 register, shown in

programmed acquisition time and justification.

U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

—— CHS3 CHS2 CHS1 CHS0 GO/DONE ADON

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5-2 CHS3:CHS0: Analog Channel Select bits

0000 = Channel 0 (AN0)

0001 = Channel 1 (AN1)

0010 = Channel 2 (AN2)

0011 = Channel 3 (AN3)

0100 = Channel 4 (AN4)

0101 = Channel 5 (AN5)(1,2)

0110 = Channel 6 (AN6)(1,2)

0111 = Channel 7 (AN7)(1,2)

1000 = Channel 8 (AN8)

1001 = Channel 9 (AN9)

1010 = Channel 10 (AN10)

1011 = Unused

1100 = Unused

1101 = Unused

1110 = Unused

1111 = Unused

Note 1: These channels are not implemented on PIC18F2X8X devices.

2: Performing a conversion on unimplemented channels will return full-scale

measurements.

bit 1 GO/DONE: A/D Conversion Status bit

When ADON = 1:

1 = A/D conversion in progress

0 = A/D Idle

bit 0 ADON: A/D On bit

1 = A/D converter module is enabled

0 = A/D converter module is disabled

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

U-0 U-0 R/W-0 R/W-0 R/W-0(1) R/W-q(1) R/W-q(1) R/W-q(1)

—— VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5 VCFG1: Voltage Reference Configuration bit (VREF- source)

1 = VREF- (AN2)

0 = AVSS

bit 4 VCFG0: Voltage Reference Configuration bit (VREF+ source)

1 = VREF+ (AN3)

0 = AVDD

bit 3-0 PCFG3:PCFG0: A/D Port Configuration Control bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

A = Analog input D = Digital I/O

Note 1: The POR value of the PCFG bits depends on the value of the PBADEN bit in

Configuration Register 3H. When PBADEN = 1, PCFG<3:0> = 0000;

when PBADEN = 0, PCFG<3:0> = 0111.

2: AN5 through AN7 are available only in PIC18F4X8X devices.

PCFG3:

PCFG0

AN10

AN9

AN8

AN7(2)

AN6(2)

AN5(2)

AN4

AN3

AN2

AN1

AN0

0000(1) AAAAAAAAAAA

0001 AAAAAAAAAAA

0010 AAAAAAAAAAA

0011 AAAAAAAAAAA

0100 AAAAAAAAAAA

0101 DAAAAAAAAAA

0110 DDAAAAAAAAA

0111(1) DDDAAAAAAAA

1000 DDDDAAAAAAA

1001 DDDDDAAAAAA

1010 DDDDDDAAAAA

1011 DDDDDDDAAAA

1100 DDDDDDDDAAA

1101 DDDDDDDDDAA

1110 DDDDDDDDDDA

1111 DDDDDDDDDDD

PIC18F2585/2680/4585/4680

R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

ADFM — ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0

bit 7 bit 0

bit 7 ADFM: A/D Result Format Select bit

1 = Right justified

0 = Left justified

bit 6 Unimplemented: Read as ‘0’

bit 5-3 ACQT2:ACQT0: A/D Acquisition Time Select bits

111 = 20 T

110 = 16 TAD

101 = 12 TAD

100 = 8 TAD

011 = 6 TAD

010 = 4 TAD

001 = 2 TAD

000 = 0 TAD(1)

bit 2-0 ADCS2:ADCS0: A/D Conversion Clock Select bits

111 = FRC (clock derived from A/D RC oscillator)(1)

110 = FOSC/64

101 = FOSC/16

100 = FOSC/4

011 = FRC (clock derived from A/D RC oscillator)(1)

010 = FOSC/32

001 = FOSC/8

000 = FOSC/2

Note 1: If the A/D FRC clock source is selected, a delay of one TCY (instruction cycle) is

added before the A/D clock starts. This allows the SLEEP instruction to be executed

before starting a conversion.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

The analog reference voltage is software selectable to

either the device’s positive and negative supply voltage

(AVDD and AVSS), or the voltage level on the

RA3/AN3/VREF+ and RA2/AN2/VREF-/CVREF pins.

The A/D converter has a unique feature of being able

to operate while the device is in Sleep mode. To

operate in Sleep, the A/D conversion clock must be

derived from the A/D’s internal RC oscillator.

The output of the sample and hold is the input into the

converter, which generates the result via successive

approximation.

A device Reset forces all registers to their Reset state.

This forces the A/D module to be turned off and any

conversion in progress is aborted.

Each port pin associated with the A/D converter can be

configured as an analog input, or as a digital I/O. The

ADRESH and ADRESL registers contain the result of

the A/D conversion. When the A/D conversion is com-

plete, the result is loaded into the ADRESH/ADRESL

registers, the GO/DONE bit (ADCON0 register) is

cleared and A/D Interrupt Flag bit ADIF is set. The

block diagram of the A/D module is shown in

Figure 19-1.

FIGURE 19-1: A/D BLOCK DIAGRAM

(Input Voltage)

VAIN

VREF+

Reference

Voltage

AVDD

VCFG1:VCFG0

CHS3:CHS0

AN7(1)

AN6(1)

AN5(1)

AN4

AN3

AN2

AN1

AN0

0111

0110

0101

0100

0011

0010

0001

0000

10-Bit

Converter

VREF-

AVSS

A/D

AN10

AN9

AN8

1010

1001

1000

Note 1: Channels AN5 through AN7 are not available on PIC18F2X8X devices.

2: I/O pins have diode protection to VDD and VSS.

PIC18F2585/2680/4585/4680

The value in the ADRESH/ADRESL registers is not

modified for a Power-on Reset. The ADRESH/ADRESL

registers will contain unknown data after a Power-on

Reset.

After the A/D module has been configured as desired,

the selected channel must be acquired before the con-

version is started. The analog input channels must

have their corresponding TRIS bits selected as an

input. To determine acquisition time, see Section 19.1

“A/D Acquisition Requirements”. After this acquisi-

tion time has elapsed, the A/D conversion can be

started. An acquisition time can be programmed to

occur between setting the GO/DONE bit and the actual

start of the conversion.

The following steps should be followed to perform an

A/D conversion:

1. Configure the A/D module:

• Configure analog pins, voltage reference and

digital I/O (ADCON1)

• Select A/D input channel (ADCON0)

• Select A/D acquisition time (ADCON2)

• Select A/D conversion clock (ADCON2)

• Turn on A/D module (ADCON0)

2. Configure A/D interrupt (if desired):

• Clear ADIF bit

• Set ADIE bit

• Set GIE bit

3. Wait the required acquisition time (if required).

4. Start conversion:

• Set GO/DONE bit (ADCON0 register)

5. Wait for A/D conversion to complete, by either:

• Polling for the GO/DONE bit to be cleared

• Waiting for the A/D interrupt

6. Read A/D Result registers (ADRESH:ADRESL);

clear bit ADIF, if required.

7. For next conversion, go to step 1 or step 2, as

required. The A/D conversion time per bit is

defined as T

AD. A minimum wait of 2 TAD is

required before next acquisition starts.

FIGURE 19-2: ANALOG INPUT MODEL

VAIN CPIN

Rs ANx

5 pF

VDD

VT = 0.6V

VT = 0.6V ILEAKAGE

RIC ≤ 1k

Sampling

Switch

SS RSS

CHOLD = 120 pF

VSS

Sampling Switch

567891011

(kΩ)

VDD

± 500 nA

Legend: CPIN

ILEAKAGE

RIC

CHOLD

= input capacitance

= threshold voltage

= leakage current at the pin due to

= interconnect resistance

= sampling switch

= sample/hold capacitance (from DAC)

various junctions

= sampling switch resistanceRSS

PIC18F2585/2680/4585/4680

19.1 A/D Acquisition Requirements

For the A/D converter to meet its specified accuracy,

the charge holding capacitor (CHOLD) must be allowed

to fully charge to the input channel voltage level. The

analog input model is shown in Figure 19-2. The

source impedance (RS) and the internal sampling

switch (RSS) impedance directly affect the time

required to charge the capacitor CHOLD. The sampling

switch (RSS) impedance varies over the device voltage

(VDD). The source impedance affects the offset voltage

at the analog input (due to pin leakage current). The

maximum recommended impedance for analog

sources is 2.5 kΩ. After the analog input channel is

selected (changed), the channel must be sampled for

at least the minimum acquisition time before starting a

conversion.

To calculate the minimum acquisition time,

Equation 19-1 may be used. This equation assumes

that 1/2 LSb error is used (1024 steps for the A/D). The

1/2 LSb error is the maximum error allowed for the A/D

to meet its specified resolution.

Example 19-3 shows the calculation of the minimum

required acquisition time TACQ. This calculation is

based on the following application system

assumptions:

CHOLD = 120 pF

Rs = 2.5 kΩ

Conversion Error ≤1/2 LSb

VDD =5V → Rss = 7 kΩ

Temperature = 50°C (system max.)

VHOLD = 0V @ time = 0

EQUATION 19-1: ACQUISITION TIME

EQUATION 19-2: A/D MINIMUM CHARGING TIME

EQUATION 19-3: CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME

Note: When the conversion is started, the

holding capacitor is disconnected from the

input pin.

TACQ = Amplifier Settli ng Time + Holdi ng Capacitor Charging Time + Temperatur e Coeffici ent

AMP + TC + TCOFF

VHOLD = (VREF – (VREF/2048)) • (1 – e(-Tc/CHOLD(RIC + RSS + RS)))

TC = -(CHOLD)(RIC + RSS + RS) ln(1/2048)

TACQ =TAMP + TC + TCOFF

TAMP =5 μs

TCOFF = (Temp – 25°C)(0.05 μs/°C)

(50°C – 25°C)(0.05 μs/°C)

1.25 μs

Temperature coefficient is only required for temperatures > 25°C. Below 25°C, TCOFF = 0 ms.

TC = -(CHOLD)(RIC + RSS + RS) ln(1/2047) μs

-(120 pF) (1 kΩ + 7 kΩ + 2.5 kΩ) ln( 0 .0 00 4883) μs

9.61 μs

TACQ =5 μs + 1.25 μs + 9.61 μs

12.86 μs

PIC18F2585/2680/4585/4680

19.2 Selecting and Configuring

Automatic Acquisition Time

The ADCON2 register allows the user to select an

acquisition time that occurs each time the GO/DONE

bit is set.

When the GO/DONE bit is set, sampling is stopped and

a conversion begins. The user is responsible for ensur-

ing the required acquisition time has passed between

selecting the desired input channel and setting the

GO/DONE bit. This occurs when the ACQT2:ACQT0

bits (ADCON2<5:3>) remain in their Reset state (‘000’)

and is compatible with devices that do not offer

programmable acquisition times.

If desired, the ACQT bits can be set to select a

programmable acquisition time for the A/D module.

When the GO/DONE bit is set, the A/D module

continues to sample the input for the selected

acquisition time, then automatically begins a

conversion. Since the acquisition time is programmed,

there may be no need to wait for an acquisition time

between selecting a channel and setting the GO/DONE

bit.

In either case, when the conversion is completed, the

GO/DONE bit is cleared, the ADIF flag is set and the

A/D begins sampling the currently selected channel

again. If an acquisition time is programmed, there is

nothing to indicate if the acquisition time has ended or

if the conversion has begun.

19.3 Selecting the A/D Conversion

Clock

The A/D conversion time per bit is defined as TAD. The

A/D conversion requires 11 TAD per 10-bit conversion.

The source of the A/D conversion clock is software

selectable. There are seven possible options for T

AD:

•2 T

OSC

•4 TOSC

•8 TOSC

•16 TOSC

•32 TOSC

•64 TOSC

• Internal RC Oscillator

For correct A/D conversions, the A/D conversion clock

(TAD) must be as short as possible, but greater than the

minimum TAD (approximately 2 μs, see parameter 130

for more information).

Table 19-1 shows the resultant T

AD times derived from

the device operating frequencies and the A/D clock

source selected.

TABLE 19-1: TAD vs. DEVICE OPERATING FREQUENCIES

AD Clock Source (TAD) Maximum Device Frequency

Operation ADCS2:ADCS0 PIC18FX585/X680 PIC18LFX585/X680(4)

2 T

OSC 000 2.86 MHz 1.43 kHz

4 TOSC 100 5.71 MHz 2.86 MHz

8 T

OSC 001 11.43 MHz 5.72 MHz

16 TOSC 101 22.86 MHz 11.43 MHz

32 T

OSC 010 40.0 MHz 22.86 MHz

64 T

OSC 110 40.0 MHz 22.86 MHz

RC(3) x11 1.00 MHz(1) 1.00 MHz(2)

Note 1: The RC source has a typical TAD time of 4 ms.

2: The RC source has a typical TAD time of 6 ms.

3: For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D

accuracy may be out of specification.

4: Low-power (PIC18LFXXXX) devices only.

PIC18F2585/2680/4585/4680

19.4 Operation in Power Managed

Modes

The selection of the automatic acquisition time and A/D

conversion clock is determined in part, by the clock

source and frequency while in a power managed mode.

If the A/D is expected to operate while the device is in

a power managed mode, the ACQT2:ACQT0 and

ADCS2:ADCS0 bits in ADCON2 should be updated in

accordance with the clock source to be used in that

mode. After entering the mode, an A/D acquisition or

conversion may be started. Once started, the device

should continue to be clocked by the same clock

source until the conversion has been completed.

If desired, the device may be placed into the

corresponding Idle mode during the conversion. If the

device clock frequency is less than 1 MHz, the A/D RC

clock source should be selected.

Operation in the Sleep mode requires the A/D FRC

clock to be selected. If bits ACQT2:ACQT0 are set to

‘000’ and a conversion is started, the conversion will be

delayed one instruction cycle to allow execution of the

SLEEP instruction and entry to Sleep mode. The IDLEN

bit (OSCCON<7>) must have already been cleared

prior to starting the conversion.

19.5 Configuring Analog Port Pins

The ADCON1, TRISA, TRISB and TRISE registers all

configure the A/D port pins. The port pins needed as

analog inputs must have their corresponding TRIS bits

set (input). If the TRIS bit is cleared (output), the digital

output level (VOH or VOL) will be converted.

The A/D operation is independent of the state of the

CHS3:CHS0 bits and the TRIS bits.

Note 1: When reading the Port register, all pins

configured as analog input channels will

read as cleared (a low level). Pins config-

ured as digital inputs will convert an

analog input. Analog levels on a digitally

configured input will be accurately

converted.

2: Analog levels on any pin defined as a

digital input may cause the digital input

buffer to consume current out of the

device’s specification limits.

3: The PBADEN bit in Configuration

reset as analog or digital pins by control-

ling how the PCFG0 bits in ADCON1 are

reset.

PIC18F2585/2680/4585/4680

19.6 A/D Conversions

Figure 19-3 shows the operation of the A/D converter

after the GO bit has been set and the ACQT2:ACQT0

bits are cleared. A conversion is started after the follow-

ing instruction to allow entry into Sleep mode before the

conversion begins.

Figure 19-4 shows the operation of the A/D converter

after the GO bit has been set and the ACQT2:ACQT0

bits are set to ‘010’ and selecting a 4 TAD acquisition

time before the conversion starts.

Clearing the GO/DONE bit during a conversion will

abort the current conversion. The A/D Result register

pair will NOT be updated with the partially completed

A/D conversion sample. This means the

ADRESH:ADRESL registers will continue to contain

the value of the last completed conversion (or the last

value written to the ADRESH:ADRESL registers).

After the A/D conversion is completed or aborted, a

AD wait is required before the next acquisition can

be started. After this wait, acquisition on the selected

channel is automatically started.

FIGURE 19-3: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0)

FIGURE 19-4: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD)

Note: The GO/DONE bit should NOT be set in

the same instruction that turns on the A/D.

TAD1TAD2TAD3TAD4 TAD5TAD6 TAD7TAD8 TAD11

Set GO bit

Holding capacitor is disconnected from analog input (typically 100 ns)

TAD9 TAD10

TCY - TAD

ADRESH:ADRESL is loaded, GO bit is cleared,

ADIF bit is set, holding capacitor is connected to analog input.

Conversion starts

b9 b6 b5 b4 b3 b2 b1

b8 b7

On the following cycle:

123 4 5 67811

Set GO bit

(Holding capacitor is disconnected)

910

Conversion starts

123 4

(Holding capacitor continues

acquiring input)

TACQT Cycles TAD Cycles

Automatic

Acquisition

Time

b0b9 b6 b5 b4 b3 b2 b1

b8 b7

ADRESH:ADRESL is loaded, GO bit is cleared,

ADIF bit is set, holding capacitor is connected to analog input.

On the following cycle:

PIC18F2585/2680/4585/4680
DS39625C-page 256 Preliminary © 2007 Microchip Technology Inc.
19.7 Use of the CCP1 Trigger
An A/D conversion can be started by the “special event
trigger” of the ECCP1 module. This requires that the
ECCP1M3:ECCP1M0 bits (ECCP1CON<3:0>) be
programmed as ‘1011’ and that the A/D module is
enabled (ADON bit is set). When the trigger occurs, the
GO/DONE bit will be set, starting the A/D acquisition
and conversion and the Timer1 (or Timer3) counter will
be reset to zero. Timer1 (or Timer3) is reset to automat-
ically repeat the A/D acquisition period with minimal
software overhead (moving ADRESH/ADRESL to the
desired location). The appropriate analog input
channel must be selected and the minimum acquisition
period is either timed by the user, or an appropriate
TACQ time selected before the “special event trigger”
sets the GO/DONE bit (starts a conversion).
If the A/D module is not enabled (ADON is cleared), the
“special event trigger” will be ignored by the A/D
module, but will still reset the Timer1 (or Timer3)
counter.
TABLE 19-2: REGISTERS ASSOCIATED WITH A/D OPERATION     
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49
IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52
PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52
PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52
IPR2 OSCFIP CMIP(5) —EEIP BCLIP HLVDIP TMR3IP ECCP1IP(5) 51
PIR2 OSCFIF CMIF(5) —EEIF BCLIF HLVDIF TMR3IF ECCP1IF(5) 51
PIE2 OSCFIE CMIE(5) —EEIE BCLIE HLVDIE TMR3IE ECCP1IE(5) 52
ADRESH  A/D Result Register High Byte 50
ADRESL  A/D Result Register Low Byte 50
ADCON0 —— CHS3 CHS2 CHS1 CHS0 GO/DONE ADON 50
ADCON1 —— VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 50
ADCON2 ADFM — ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0 50
PORTA RA7(2) RA6(2) RA5 RA4 RA3 RA2 RA1 RA0 52
TRISA TRISA7(2) TRISA6(2) PORTA Data Direction Register 52
PORTB Read PORTB pins, Write LATB Latch 52
TRISB PORTB Data Direction Register 52
LATB PORTB Output Data Latch 52
PORTE(4) — — — —RE3
(3) Read PORTE pins, Write LATE(1) 52
TRISE(4) IBF OBF IBOV PSPMODE — PORTE Data Direction 52
LATE(4) — — — — — LATE2 LATE1 LATE0 52
Legend: — = unimplemented, read as ‘0’. Shaded cells are not used for A/D conversion.
Note 1: These bits are unimplemented on PIC18F2X8X devices; always maintain these bits clear.
2: These pins may be configured as port pins depending on the oscillator mode selected.
3: RE3 port bit is available only as an input pin when the MCLRE Configuration bit is ‘0’.
4: These registers are not implemented on PIC18F2X8X devices.
5: These bits are available on PIC18F4X8X and reserved on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

20.0 COMPARATOR MODULE

The analog comparator module contains two compara-

tors that can be configured in a variety of ways. The

inputs can be selected from the analog inputs multiplexed

with pins RA0 through RA5, as well as the on-chip volt-

age reference (see Section 21.0 “Comparator Voltage

Reference Module”). The digital outputs (normal or

inverted) are available at the pin level and can also be

read through the control register.

The CMCON register (Register 20-1) selects the

comparator input and output configuration. Block

diagrams of the various comparator configurations are

shown in Figure 20-1.

R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0

bit 7 bit 0

bit 7 C2OUT: Comparator 2 Output bit

When C2INV = 0:

1 = C2 VIN+ > C2 VIN-

0 = C2 VIN+ < C2 VIN-

When C2INV = 1:

1 = C2 VIN+ < C2 VIN-

0 = C2 VIN+ > C2 VIN-

bit 6 C1OUT: Comparator 1 Output bit

When C1INV = 0:

1 = C1 VIN+ > C1 VIN-

0 = C1 VIN+ < C1 VIN-

When C1INV = 1:

1 = C1 VIN+ < C1 VIN-

0 = C1 VIN+ > C1 VIN-

bit 5 C2INV: Comparator 2 Output Inversion bit

1 = C2 output inverted

0 = C2 output not inverted

bit 4 C1INV: Comparator 1 Output Inversion bit

1 = C1 Output inverted

0 = C1 Output not inverted

bit 3 CIS: Comparator Input Switch bit

When CM2:CM0 = 110:

1 =C1 VIN- connects to RD0/PSP0/C1IN+

C2 VIN- connects to RD2/PSP2/C2IN+

0 =C1 V

IN- connects to RD1/PSP1/C1IN-

C2 VIN- connects to RD3/PSP3/C2IN-

bit 2-0 CM2:CM0: Comparator Mode bits

Figure 20-1 shows the Comparator modes and the CM2:CM0 bit settings.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

20.1 Comparator Configuration

There are eight modes of operation for the compara-

tors, shown in Figure 20-1. Bits CM2:CM0 of the

CMCON register are used to select these modes. The

TRISA register controls the data direction of the com-

parator pins for each mode. If the Comparator mode is

changed, the comparator output level may not be valid

for the specified mode change delay shown in

Section 27.0 “Electrical Characteristics”.

FIGURE 20-1: COMPARATOR I/O OPERATING MODES

Note: Comparator interrupts should be disabled

during a Comparator mode change;

otherwise, a false interrupt may occur.

VIN-

VIN+Off

Comparators Reset (POR Default Value)

CM2:CM0 = 000

VIN-

VIN+Off

VIN-

VIN+C1OUT

Two Independent Comparators

CM2:CM0 = 010

VIN-

VIN+C2OUT

VIN-

VIN+C1OUT

Two Common Reference Comparators

CM2:CM0 = 100

VIN-

VIN+C2OUT

VIN-

VIN+Off

One Independent Comparator with Output

CM2:CM0 = 001

VIN-

VIN+C1OUT

VIN-

VIN+Off

Comparators Off

CM2:CM0 = 111

VIN-

VIN+Off

VIN-

VIN+C1OUT

Four Inputs Multiplexed to Two Comparators

CM2:CM0 = 110

VIN-

VIN+C2OUT

From VREF Module

CIS = 0

CIS = 1

CIS = 0

CIS = 1

VIN-

VIN+C1OUT

Two Common Reference Comparators with Outputs

CM2:CM0 = 101

VIN-

VIN+C2OUT

A = Analog Input, port reads zeros always D = Digital Input CIS (CMCON<3>) is the Comparator Input Switch

CVREF

VIN-

VIN+C1OUT

Two Independent Comparators with Outputs

CM2:CM0 = 011

VIN-

VIN+C2OUT

* Setting the TRISA<5:4> bits will disable the comparator outputs by configuring the pins as inputs.

(Read as ‘0’)

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RD1/PSP1/

RD0/PSP0/

RD3/PSP3/

RD2/PSP2/

C2IN-

C2IN+

C1IN+

C1IN-

RE1/WR/AN6/C1OUT*

RE2/CS/AN7/C2OUT*

RD1/PSP1/C1IN-

RD0/PSP0/C1IN+

RD3/PSP3/C2IN-

RD2/PSP2/C2IN+

RE1/WR/AN6/C1OUT*

RE2/CS/AN7/C2OUT*

PIC18F2585/2680/4585/4680

20.2 Comparator Operation

A single comparator is shown in Figure 20-2, along with

the relationship between the analog input levels and

the digital output. When the analog input at VIN+ is less

than the analog input VIN-, the output of the comparator

is a digital low level. When the analog input at VIN+ is

greater than the analog input VIN-, the output of the

comparator is a digital high level. The shaded areas of

the output of the comparator in Figure 20-2 represent

the uncertainty, due to input offsets and response time.

20.3 Comparator Reference

Depending on the comparator operating mode, either

an external or internal voltage reference may be used.

The analog signal present at VIN- is compared to the

signal at VIN+ and the digital output of the comparator

is adjusted accordingly (Figure 20-2).

FIGURE 20-2: SINGLE COMPARATOR

20.3.1 EXTERNAL REFERENCE SIGNAL

When external voltage references are used, the

comparator module can be configured to have the com-

parators operate from the same or different reference

sources. However, threshold detector applications may

require the same reference. The reference signal must

be between VSS and VDD and can be applied to either

pin of the comparator(s).

20.3.2 INTERNAL REFERENCE SIGNAL

The comparator module also allows the selection of an

internally generated voltage reference from the

comparator voltage reference module. This module is

described in more detail in Section 21.0 “Comparator

Voltage Reference Module”.

The internal reference is only available in the mode

where four inputs are multiplexed to two comparators

(CM2:CM0 = 110). In this mode, the internal voltage

reference is applied to the VIN+ pin of both

comparators.

20.4 Comparator Response Time

Response time is the minimum time, after selecting a

new reference voltage or input source, before the

comparator output has a valid level. If the internal

reference is changed, the maximum delay of the

internal voltage reference must be considered when

using the comparator outputs. Otherwise, the

maximum delay of the comparators should be used

(see Section 27.0 “Electrical Characteristics”).

20.5 Comparator Outputs

The comparator outputs are read through the CMCON

outputs may also be directly output to the RE1 and RE2

I/O pins. When enabled, multiplexors in the output path

of the RE1 and RE2 pins will switch and the output of

each pin will be the unsynchronized output of the

comparator. The uncertainty of each of the

comparators is related to the input offset voltage and

the response time given in the specifications.

Figure 20-3 shows the comparator output block

diagram.

The TRISE bits will still function as an output enable/

disable for the RE1 and RE2 pins while in this mode.

The polarity of the comparator outputs can be changed

using the C2INV and C1INV bits (CMCON<4:5>).

–

VIN+

VIN-

Output

VIN-

VIN+

Note 1: When reading the Port register, all pins

configured as analog inputs will read as a

‘0’. Pins configured as digital inputs will

convert an analog input according to the

Schmitt Trigger input specification.

2: Analog levels on any pin defined as a

digital input may cause the input buffer to

consume more current than is specified.

PIC18F2585/2680/4585/4680

FIGURE 20-3: COMPARATOR OUTPUT BLOCK DIAGRAM

20.6 Comparator Interrupts

The comparator interrupt flag is set whenever there is

a change in the output value of either comparator.

Software will need to maintain information about the

status of the output bits, as read from CMCON<7:6>, to

determine the actual change that occurred. The CMIF

bit (PIR2<6>) is the Comparator Interrupt Flag. The

CMIF bit must be reset by clearing it. Since it is also

possible to write a ‘1’ to this register, a simulated

interrupt may be initiated.

Both the CMIE bit (PIE2<6>) and the PEIE bit

(INTCON<6>) must be set to enable the interrupt. In

addition, the GIE bit (INTCON<7>) must also be set. If

any of these bits are clear, the interrupt is not enabled,

though the CMIF bit will still be set if an interrupt

condition occurs.

The user, in the Interrupt Service Routine, can clear the

interrupt in the following manner:

a) Any read or write of CMCON will end the

mismatch condition.

b) Clear flag bit CMIF.

A mismatch condition will continue to set flag bit CMIF.

Reading CMCON will end the mismatch condition and

allow flag bit CMIF to be cleared.

20.7 Comparator Operation

During Sleep

When a comparator is active and the device is placed

in Sleep mode, the comparator remains active and the

interrupt is functional if enabled. This interrupt will

wake-up the device from Sleep mode, when enabled.

While the comparator is powered up, higher Sleep

currents than shown in the power-down current

specification will occur. Each operational comparator

will consume additional current, as shown in the

comparator specifications. To minimize power

consumption while in Sleep mode, turn off the

comparators (CM2:CM0 = 111) before entering Sleep.

If the device wakes up from Sleep, the contents of the

CMCON register are not affected.

20.8 Effects of a Reset

A device Reset forces the CMCON register to its Reset

state, causing the comparator module to be in the Com-

parator Reset mode (CM2:CM0 = 000). This ensures

that all potential inputs are analog inputs. Device

current is minimized when analog inputs are present at

Reset time. The comparators are powered down during

the Reset interval.

To RE 1 or

RE2 pin

Bus

Data

Set

MULTIPLEX

CMIF

bit

Port pins

Read CMCON

Reset

From

other

Comparator

CxINV

EN CL

Note: If a change in the CMCON register

(C1OUT or C2OUT) should occur when a

read operation is being executed (start of

the Q2 cycle), then the CMIF (PIR

registers) interrupt flag may not get set.

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 261
PIC18F2585/2680/4585/4680
20.9 Analog Input Connection
Considerations
A simplified circuit for an analog input is shown in
Figure 20-4. Since the analog pins are connected to a
digital output, they have reverse biased diodes to VDD
and VSS. The analog input, therefore, must be between
VSS and VDD. If the input voltage deviates from this
range by more than 0.6V in either direction, one of the
diodes is forward biased and a latch-up condition may
occur. A maximum source impedance of 10 kΩ is
recommended for the analog sources. Any external
component connected to an analog input pin, such as
a capacitor or a Zener diode, should have very little
leakage current.
FIGURE 20-4: COMPARATOR ANALOG INPUT MODEL        
TABLE 20-1: REGISTERS ASSOCIATED WITH COMPARATOR MODULE  
VA
RS < 10k
AIN
CPIN
5 pF
VDD
VT = 0.6V
VT = 0.6V
RIC
ILEAKAGE
±500 nA
VSS
Legend: CPIN = Input Capacitance
VT= Threshold Voltage
ILEAKAGE =  Leakage Current at the pin due to various junctions
RIC = Interconnect Resistance
RS= Source Impedance
VA = Analog Voltage
Comparator
Input
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Reset 
Values 
on page
CMCON(3) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51
CVRCON(3) CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51
INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 52
IPR2 OSCFIP CMIP(2) —EEIP BCLIP HLVDIP TMR3IP ECCP1IP(2) 51
PIR2 OSCFIF CMIF(2) —EEIF BCLIF HLVDIF TMR3IF ECCP1IF(2) 51
PIE2 OSCFIE CMIE(2) —EEIE BCLIE HLVDIE TMR3IE ECCP1IE(2) 52
PORTA RA7(1) RA6(1) RA5 RA4 RA3 RA2 RA1 RA0 52
LATA LATA7(1) LATA6(1) LATA Data Output Register 52
TRISA TRISA7(1) TRISA6(1) PORTA Data Direction Register 52
Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the comparator module.
Note 1: PORTA pins are enabled based on oscillator configuration.
2: These bits are available in PIC18F4X8X devices and reserved in PIC18F2X8X devices.
3: These registers are unimplemented on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

21.0 COMPARATOR VOLTAGE

REFERENCE MODULE

The comparator voltage reference is a 16-tap resistor

ladder network that provides a selectable reference

voltage. Although its primary purpose is to provide a

reference for the analog comparators, it may also be

used independently of them.

A block diagram is of the module shown in Figure 21-1.

The resistor ladder is segmented to provide two ranges

of CVREF values and has a power-down function to

conserve power when the reference is not being used.

The module’s supply reference can be provided from

either device VDD/VSS or an external voltage reference.

21.1 Configuring the Comparator

Voltage Reference

The voltage reference module is controlled through the

CVRCON register (Register 21-1). The comparator

voltage reference provides two ranges of output

voltage, each with 16 distinct levels. The range to be

used is selected by the CVRR bit (CVRCON<5>). The

primary difference between the ranges is the size of the

steps selected by the CVREF Selection bits

(CVR3:CVR0), with one range offering finer resolution.

The equations used to calculate the output of the

comparator voltage reference are as follows:

If CVRR = 1:

CVREF = ((CVR3:CVR0)/24) x CVRSRC

If CVRR = 0:

CVREF = (CVDD x 1/4) + (((CVR3:CVR0)/32) x

CVRSRC)

The comparator reference supply voltage can come

from either VDD and VSS, or the external VREF+ and

VREF- that are multiplexed with RA2 and RA3. The

voltage source is selected by the CVRSS bit

(CVRCON<4>).

The settling time of the comparator voltage reference

must be considered when changing the CVREF output

(see Table 27-3 in Section 27.0 “Electrical

Characteristics”).

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

CVREN CVROE(1) CVRR CVRSS CVR3 CVR2 CVR1 CVR0

bit 7 bit 0

bit 7 CVREN: Comparator Voltage Reference Enable bit

1 = CVREF circuit powered on

0 = CVREF circuit powered down

bit 6 CVROE: Comparator VREF Output Enable bit(1)

1 = CVREF voltage level is also output on the RA0/AN0/CVREF pin

0 = CVREF voltage is disconnected from the RA0/AN0/CVREF pin

Note 1: CVROE overrides the TRISA<0> bit setting. If enabled for output, RA2 must also

be configured as an input by setting TRISA<2> to ‘1’.

bit 5 CVRR: Comparator VREF Range Selection bit

1 = 0.00 CVRSRC to 0.75 CVRSRC, with CVRSRC/24 step size

0 = 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size

bit 4 CVRSS: Comparator VREF Source Selection bit

1 = Comparator reference source, CVRSRC = (VREF+) – (VREF-)

0 = Comparator reference source, CVRSRC = VDD – VSS

bit 3-0 CVR3:CVR0: Comparator VREF Value Selection bits (0 ≤ (CVR3:CVR0) ≤ 15)

When CVRR = 1:

CVREF = ((CVR3:CVR0)/24) • (CVRSRC)

When CVRR = 0:

CVREF = (CVRSRC/4) + ((CVR3:CVR0)/32) • (CVRSRC)

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

FIGURE 21-1: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM

21.2 Voltage Reference Accuracy/Error

The full range of voltage reference cannot be realized

due to the construction of the module. The transistors

on the top and bottom of the resistor ladder network

(Figure 21-1) keep CVREF from approaching the

reference source rails. The voltage reference is derived

from the reference source; therefore, the CVREF output

changes with fluctuations in that source. The tested

absolute accuracy of the voltage reference can be

found in Section 27.0 “Electrical Characteristics”.

21.3 Operation During Sleep

When the device wakes up from Sleep through an

interrupt or a Watchdog Timer time-out, the contents of

the CVRCON register are not affected. To minimize

current consumption in Sleep mode, the voltage

reference should be disabled.

21.4 Effects of a Reset

A device Reset disables the voltage reference by

clearing bit CVREN (CVRCON<7>). This Reset also

disconnects the reference from the RA0 pin by clearing

bit CVROE (CVRCON<6>) and selects the high-voltage

range by clearing bit CVRR (CVRCON<5>). The CVR

value select bits are also cleared.

21.5 Connection Considerations

The voltage reference module operates independently

of the comparator module. The output of the reference

generator may be connected to the RA0 pin if the

TRISA<0> bit and the CVROE bit are both set.

Enabling the voltage reference output onto the RA0

pin, with an input signal present, will increase current

consumption. Connecting RA0 as a digital output with

CVRSS enabled will also increase current

consumption.

The RA0 pin can be used as a simple D/A output with

limited drive capability. Due to the limited current drive

capability, a buffer must be used on the voltage

reference output for external connections to VREF.

Figure 21-2 shows an example buffering technique.

16 to 1 MUX

CVR3:CVR0

CVREN

CVRSS = 0

VDD

VREF+CVRSS = 1

CVRSS = 0

VREF-CVRSS = 1

16 Steps

CVRR

CVREF

PIC18F2585/2680/4585/4680

FIGURE 21-2: VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE

TABLE 21-1: REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE

CVREF Output

–

CVREF

Module

Voltage

Reference

Output

Impedance

R(1)

RA0

Note 1: R is dependent upon the voltage reference configuration bits, CVRCON<3:0> and CVRCON<5>.

PIC18F4X8X

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on page

CVRCON(2) CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51

CMCON(2) C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51

TRISA TRISA7(1) TRISA6(1) PORTA Data Direction Register 52

Legend: Shaded cells are not used with the comparator voltage reference.

Note 1: PORTA pins are enabled based on oscillator configuration.

2: These registers are unimplemented on PIC18F2X8X devices.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

22.0 HIGH/LOW-VOLTAGE

DETECT (HLVD)

PIC18F2585/2680/4585/4680 devices have a

High/Low-Voltage Detect module (HLVD). This is a

programmable circuit that allows the user to specify

both a device voltage trip point and the direction of

change from that point. If the device experiences an

excursion past the trip point in that direction, an

interrupt flag is set. If the interrupt is enabled, the

program execution will branch to the interrupt vector

address and the software can then respond to the

interrupt.

The High/Low-Voltage Detect Control register

(Register 22-1) completely controls the operation of the

HLVD module. This allows the circuitry to be “turned

off” by the user under software control, which

minimizes the current consumption for the device.

The block diagram for the HLVD module is shown in

Figure 22-1.

R/W-0 U-0 R-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1

VDIRMAG — IRVST HLVDEN HLVDL3(1) HLVDL2(1) HLVDL1(1) HLVDL0(1)

bit 7 bit 0

bit 7 VDIRMAG: Voltage Direction Magnitude Select bit

1 = Event occurs when voltage equals or exceeds trip point (HLVDL3:HLDVL0)

0 = Event occurs when voltage equals or falls below trip point (HLVDL3:HLVDL0)

bit 6 Unimplemented: Read as ‘0’

bit 5 IRVST: Internal Reference Voltage Stable Flag bit

1 = Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage

range

0 = Indicates that the voltage detect logic will not generate the interrupt flag at the specified

voltage range and the HLVD interrupt should not be enabled

bit 4 HLVDEN: High/Low-Voltage Detect Power Enable bit

1 = HLVD enabled

0 = HLVD disabled

bit 3-0 HLVDL3:HLVDL0: Voltage Detection Limit bits(1)

1111 = External analog input is used (input comes from the HLVDIN pin)

1110 = 4.48V-4.69V

1101 = 4.23V-4.43V

1100 = 4.01V-4.20V

1011 = 3.81V-3.99V

1010 = 3.63V-3.80V

1001 = 3.46V-3.63V

1000 = 3.31V-3.47V

0111 = 3.05V-3.19V

0110 = 2.82V-2.95V

0101 = 2.72V-2.85V

0100 = 2.54V-2.66V

0011 = 2.38V-2.49V

0010 = 2.31V-2.42V

0001 = 2.18V-2.28V

0000 = 2.12V-2.22V

Note 1: HLVDL3:HLVDL0 modes that result in a trip point below the valid operating voltage

of the device are not tested.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

The module is enabled by setting the HLVDEN bit.

Each time that the HLVD module is enabled, the

circuitry requires some time to stabilize. The IRVST bit

is a read-only bit and is used to indicate when the circuit

is stable. The module can only generate an interrupt

after the circuit is stable and IRVST is set.

The VDIRMAG bit determines the overall operation of

the module. When VDIRMAG is cleared, the module

monitors for drops in VDD below a predetermined set

point. When the bit is set, the module monitors for rises

in VDD above the set point.

22.1 Operation

When the HLVD module is enabled, a comparator uses

an internally generated reference voltage as the set

point. The set point is compared with the trip point,

where each node in the resistor divider represents a

trip point voltage. The “trip point” voltage is the voltage

level at which the device detects a high or low-voltage

event, depending on the configuration of the module.

When the supply voltage is equal to the trip point, the

voltage tapped off of the resistor array is equal to the

internal reference voltage generated by the voltage

reference module. The comparator then generates an

interrupt signal by setting the HLVDIF bit.

The trip point voltage is software programmable to any

one of sixteen values. The trip point is selected

by programming the HLVDL3:HLVDL0 bits

(HLVDCON<3:0>).

The HLVD module has an additional feature that allows

the user to supply the trip voltage to the module from an

external source. This mode is enabled when bits

HLVDL3:HLVDL0 are set to ‘1111’. In this state, the

comparator input is multiplexed from the external input

pin, HLVDIN. This gives users flexibility because it

allows them to configure the High/Low-Voltage Detect

interrupt to occur at any voltage in the valid operating

range.

FIGURE 22-1: HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT)

Set

VDD

16 to 1 MUX

HLVDEN

HLVDCON

HLVDIN

HLVDL3:HLVDL0

HLVDIN

VDD

Externally Generated

Trip Point

HLVDIF

HLVDEN

BOREN

Internal Voltage

Reference

VDIRMAG

PIC18F2585/2680/4585/4680

22.2 HLVD Setup

The following steps are needed to set up the HLVD

module:

1. Disable the module by clearing the HLVDEN bit

(HLVDCON<4>).

2. Write the value to the HLVDL3:HLVDL0 bits that

select the desired HLVD trip point.

3. Set the VDIRMAG bit to detect high voltage

(VDIRMAG = 1) or low voltage (VDIRMAG = 0).

4. Enable the HLVD module by setting the

HLVDEN bit.

5. Clear the HLVD interrupt flag (PIR2<2>), which

may have been set from a previous interrupt.

6. Enable the HLVD interrupt if interrupts are

desired by setting the HLVDIE and GIE bits

(PIE<2> and INTCON<7>). An interrupt will not

be generated until the IRVST bit is set.

22.3 Current Consumption

When the module is enabled, the HLVD comparator

and voltage divider are enabled and will consume static

current. The total current consumption, when enabled,

is specified in electrical specification parameter D022B.

Depending on the application, the HLVD module does

not need to be operating constantly. To decrease the

current requirements, the HLVD circuitry may only

need to be enabled for short periods where the voltage

is checked. After doing the check, the HLVD module

may be disabled.

22.4 HLVD Start-up Time

The internal reference voltage of the HLVD module,

specified in electrical specification parameter D420,

may be used by other internal circuitry, such as the

Programmable Brown-out Reset. If the HLVD or other

circuits using the voltage reference are disabled to

lower the device’s current consumption, the reference

voltage circuit will require time to become stable before

a low or high-voltage condition can be reliably

detected. This start-up time, TIRVST, is an interval that

is independent of device clock speed. It is specified in

electrical specification parameter 36.

The HLVD interrupt flag is not enabled until TIRVST has

expired and a stable reference voltage is reached. For

this reason, brief excursions beyond the set point may

not be detected during this interval. Refer to

Figure 22-2 or Figure 22-3.

FIGURE 22-2: LOW-VOLTAGE DETECT OPERATION (VDIRMAG = 0)

VLVD

VDD

HLVDIF

VLVD

VDD

Enable HLVD

TIRVST

HLVDIF may not be set

Enable HLVD

HLVDIF

HLVDIF cleared in software

HLVDIF cleared in software,

CASE 1:

CASE 2:

HLVDIF remains set since HLVD condition still exists

TIRVST

Internal Reference is stable

IRVST

PIC18F2585/2680/4585/4680

FIGURE 22-3: HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1)

22.5 Applications

In many applications, the ability to detect a drop below,

or rise above a particular threshold is desirable. For

example, the HLVD module could be periodically

enabled to detect Universal Serial Bus (USB) attach or

detach. This assumes the device is powered by a lower

voltage source than the USB when detached. An attach

would indicate a high-voltage detect from, for example,

3.3V to 5V (the voltage on USB) and vice versa for a

detach. This feature could save a design a few extra

components and an attach signal (input pin).

For general battery applications, Figure 22-4 shows a

possible voltage curve. Over time, the device voltage

decreases. When the device voltage reaches voltage

VA, the HLVD logic generates an interrupt at time TA.

The interrupt could cause the execution of an ISR,

which would allow the application to perform “house-

keeping tasks” and perform a controlled shutdown

before the device voltage exits the valid operating

range at TB. The HLVD, thus, would give the

application a time window, represented by the

difference between TA and TB, to safely exit.

FIGURE 22-4: TYPICAL LOW-VOLTAGE

DETECT APPLICATION

VLVD

VDD

HLVDIF

VLVD

VDD

Enable HLVD

TIRVST

HLVDIF may not be set

Enable HLVD

HLVDIF

HLVDIF cleared in software

HLVDIF cleared in software,

CASE 1:

CASE 2:

HLVDIF remains set since HLVD condition still exists

TIRVST

IRVST

Internal Reference is stable

IRVST

Time

Voltage

TATB

VA = HLVD trip point

VB = Minimum valid device

operating voltage

Legend:

PIC18F2585/2680/4585/4680

22.6 Operation During Sleep

When enabled, the HLVD circuitry continues to operate

during Sleep. If the device voltage crosses the trip

point, the HLVDIF bit will be set and the device will

wake-up from Sleep. Device execution will continue

from the interrupt vector address if interrupts have

been globally enabled.

22.7 Effects of a Reset

A device Reset forces all registers to their Reset state.

This forces the HLVD module to be turned off.

TABLE 22-1: REGISTERS ASSOCIATED WITH HIGH/LOW-VOLTAGE DETECT MODULE

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reset

Values

on Page

HLVDCON VDIRMAG — IRVST HLVDEN HLVDL3 HLVDL2 HLVDL1 HLVDL0 50

INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49

PIR2 OSCFIF CMIF — EEIF BCLIF HLVDIF TMR3IF ECCP1IF 51

PIE2 OSCFIE CMIE —EEIE BCLIE HLVDIE TMR3IE ECCP1IE 52

IPR2 OSCFIP CMIP —EEIP BCLIP HLVDIP TMR3IP ECCP1IP 51

Legend: — = unimplemented, read as ‘0’. Shaded cells are unused by the HLVD module.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

23.0 ECAN™ TECHNOLOGY

PIC18F2585/2680/4585/4680 devices contain an

Enhanced Controller Area Network (ECAN) module.

The ECAN module is fully backward compatible with

the CAN module available in PIC18CXX8 and

PIC18FXX8 devices.

The Controller Area Network (CAN) module is a serial

interface which is useful for communicating with other

peripherals or microcontroller devices. This interface,

or protocol, was designed to allow communications

within noisy environments.

The ECAN module is a communication controller, imple-

menting the CAN 2.0A or B protocol as defined in the

BOSCH specification. The module will support CAN 1.2,

CAN 2.0A, CAN 2.0B Passive and CAN 2.0B Active

versions of the protocol. The module implementation is

a full CAN system; however, the CAN specification is not

covered within this data sheet. Refer to the BOSCH CAN

specification for further details.

The module features are as follows:

• Implementation of the CAN protocol CAN 1.2,

CAN 2.0A and CAN 2.0B

• DeviceNetTM data bytes filter support

• Standard and extended data frames

• 0-8 bytes data length

• Programmable bit rate up to 1 Mbit/sec

• Fully backward compatible with PIC18XXX8 CAN

module

• Three modes of operation:

- Mode 0 – Legacy mode

- Mode 1 – Enhanced Legacy mode with

DeviceNet support

- Mode 2 – FIFO mode with DeviceNet support

• Support for remote frames with automated handling

• Double-buffered receiver with two prioritized

received message storage buffers

• Six buffers programmable as RX and TX

message buffers

• 16 full (standard/extended identifier) acceptance

filters that can be linked to one of four masks

• Two full acceptance filter masks that can be

assigned to any filter

• One full acceptance filter that can be used as either

an acceptance filter or acceptance filter mask

• Three dedicated transmit buffers with application

specified prioritization and abort capability

• Programmable wake-up functionality with

integrated low-pass filter

• Programmable Loopback mode supports self-test

operation

• Signaling via interrupt capabilities for all CAN

receiver and transmitter error states

• Programmable clock source

• Programmable link to timer module for

time-stamping and network synchronization

• Low-power Sleep mode

23.1 Module Overview

The CAN bus module consists of a protocol engine and

message buffering and control. The CAN protocol

engine automatically handles all functions for receiving

and transmitting messages on the CAN bus. Messages

are transmitted by first loading the appropriate data

registers. Status and errors can be checked by reading

the appropriate registers. Any message detected on

the CAN bus is checked for errors and then matched

against filters to see if it should be received and stored

in one of the two receive registers.

The CAN module supports the following frame types:

• Standard Data Frame

• Extended Data Frame

• Remote Frame

• Error Frame

• Overload Frame Reception

• Interframe Space Generation/Detection

The CAN module uses the RB2/CANTX and RB3/

CANRX pins to interface with the CAN bus. In normal

mode, the CAN module automatically overrides

TRISB<2>. The user must ensure that TRISB<3> is

set.

23.1.1 MODULE FUNCTIONALITY

The CAN bus module consists of a protocol engine,

message buffering and control (see Figure 23-1). The

protocol engine can best be understood by defining the

types of data frames to be transmitted and received by

the module.

The following sequence illustrates the necessary initial-

ization steps before the ECAN module can be used to

transmit or receive a message. Steps can be added or

removed depending on the requirements of the

application.

1. Ensure that the ECAN module is in Configuration

mode.

2. Select ECAN Operational mode.

3. Set up the baud rate registers.

4. Set up the filter and mask registers.

5. Set the ECAN module to normal mode or any

other mode required by the application logic.

PIC18F2585/2680/4585/4680

FIGURE 23-1: CAN BUFFERS AND PROTOCOL ENGINE BLOCK DIAGRAM

MSGREQ

TXB2

ABTF

MLOA

TXERR

MTXBUFF

MESSAGE

Message

Queue

Control

Transmit Byte Sequencer

MSGREQ

TXB1

ABTF

MLOA

TXERR

MTXBUFF

MESSAGE

MSGREQ

TXB0

ABTF

MLOA

TXERR

MTXBUFF

MESSAGE

Acceptance Filters

(RXF0-RXF05)

Data Field

Identifier

Acceptance Mask

RXM1

Acceptance Filters

(RXF06-RXF15)

Acceptance Mask

RXM0

Rcv Byte

16 – 4 to 1 MUXs

PROTOCOL

MESSAGE

BUFFERS

Transmit Option

MODE 0

MODE 1, 2

6 TX/RX

Buffers

2 RX

Buffers

CRC<14:0>

Comparator

Receive<8:0>Transmit<7:0>

Receive

Error

Transmit

Error

Protocol

REC

TEC

Err-Pas

Bus-Off

Finite

State

Machine

Counter

Shift<14:0>

{Transmit<5:0>, Receive<8:0>}

Transmit

Logic

Bit

Timing

Logic

TX RX Configuration

Registers

Clock

Generator

BUFFERS

ENGINE

MODE 0

MODE 1, 2

RXF15

VCC

PIC18F2585/2680/4585/4680

23.2 CAN Module Registers

There are many control and data registers associated

with the CAN module. For convenience, their

descriptions have been grouped into the following

sections:

• Control and Status Registers

• Dedicated Transmit Buffer Registers

• Dedicated Receive Buffer Registers

• Programmable TX/RX and Auto RTR Buffers

• Baud Rate Control Registers

• I/O Control Register

• Interrupt Status and Control Registers

Detailed descriptions of each register and their usage

are described in the following sections.

23.2.1 CAN CONTROL AND STATUS

REGISTERS

The registers described in this section control the

overall operation of the CAN module and show its

operational status.

Note: Not all CAN registers are available in the

access bank.

PIC18F2585/2680/4585/4680

Mode 0 R/W-1 R/W-0 R/W-0 R/S-0 R/W-0 R/W-0 R/W-0 U-0

REQOP2 REQOP1 REQOP0 ABAT WIN2 WIN1 WIN0 —

Mode 1 R/W-1 R/W-0 R/W-0 R/S-0 U-0 U-0 U-0 U-0

REQOP2 REQOP1 REQOP0 ABAT — — — —

Mode 2 R/W-1 R/W-0 R/W-0 R/S-0 R-0 R-0 R-0 R-0

REQOP2 REQOP1 REQOP0 ABAT FP3 FP2 FP1 FP0

bit 7 bit 0

bit 7-5 REQOP2:REQOP0: Request CAN Operation Mode bits

1xx = Request Configuration mode

011 = Request Listen Only mode

010 = Request Loopback mode

001 = Request Disable mode

000 = Request Normal mode

bit 4 ABAT: Abort All Pending Transmissions bit

1 = Abort all pending transmissions (in all transmit buffers)

0 = Transmissions proceeding as normal

bit 3-1 Mode 0:

WIN2:WIN0: Window Address bits

These bits select which of the CAN buffers to switch into the access bank area. This allows

access to the buffer registers from any data memory bank. After a frame has caused an

interrupt, the ICODE3:ICODE0 bits can be copied to the WIN3:WIN0 bits to select the correct

buffer. See Example 23-2 for a code example.

111 = Receive Buffer 0

110 = Receive Buffer 0

101 = Receive Buffer 1

100 = Transmit Buffer 0

011 = Transmit Buffer 1

010 = Transmit Buffer 2

001 = Receive Buffer 0

000 = Receive Buffer 0

bit 0 Unimplemented: Read as ‘0’

bit 4-0 Mode 1:

Unimplemented: Read as ‘0’

Mode 2:

FP3:FP0: FIFO Read Pointer bits

These bits point to the message buffer to be read.

0111:0000 = Message buffer to be read

1111:1000 = Reserved

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R-1 R-0 R-0 R-0 R-0 R-0 R-0 U-0

OPMODE2

(1)

OPMODE1

(1)

OPMODE0

(1)

— ICODE3 ICODE2 ICODE1 —

Mode 1, 2 R-1 R-0 R-0 R-0 R-0 R-0 R-0 R-0

OPMODE2

(1)

OPMODE1

(1)

OPMODE0

(1)

EICODE4 EICODE3 EICODE2 EICODE1 EICODE0

bit 7 bit 0

bit 7-5 OPMODE2:OPMODE0: Operation Mode Status bits(1)

111 = Reserved

110 = Reserved

101 = Reserved

100 = Configuration mode

011 = Listen Only mode

010 = Loopback mode

001 = Disable/Sleep mode

000 = Normal mode

bit 4 Mode 0:

Unimplemented: Read as ‘0’

bit 3-1 ICODE3:ICODE1: Interrupt Code bits

When an interrupt occurs, a prioritized coded interrupt value will be present in these bits. This

code indicates the source of the interrupt. By copying ICODE3:ICODE1 to WIN2:WIN0 (Mode 0)

or EICODE4:EICODE0 to EWIN4:EWIN0 (Mode 1 and 2), it is possible to select the correct

buffer to map into the Access Bank area. See Example 23-2 for a code example. To simplify the

description, the following table lists all five bits.

bit 0 Unimplemented: Read as ‘0’

bit 4-0 Mode 1, 2:

EICODE4:EICODE0: Interrupt Code bits

See ICODE3:ICODE1 above.

Note 1: To achieve maximum power saving and/or able to wake-up on CAN bus activity,

switch CAN module in Disable mode before putting device to Sleep.

2: If buffer is configured as receiver, EICODE bits will contain ‘10000’ upon interrupt.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Mode 0 Mode 1 Mode 2

No interrupt 00000 00000 00000

Error interrupt 00010 00010 00010

TXB2 interrupt 00100 00100 00100

TXB1 interrupt 00110 00110 00110

TXB0 interrupt 01000 01000 01000

RXB1 interrupt 01010 10001 -----

RXB0 interrupt 01100 10000 10000

Wake-up interrupt 00010 01110 01110

RXB0 interrupt ----- 10000 10000

RXB1 interrupt ----- 10001 10000

RX/TX B0 interrupt ----- 10010 10010

RX/TX B1 interrupt ----- 10011 10011(2)

RX/TX B2 interrupt ----- 10100 10100(2)

RX/TX B3 interrupt ----- 10101 10101(2)

RX/TX B4 interrupt ----- 10110 10110(2)

RX/TX B5 interrupt ----- 10111 10111(2)

PIC18F2585/2680/4585/4680

EXAMPLE 23-1: CHANGING TO CONFIGURATION MODE

EXAMPLE 23-2: WIN AND ICODE BITS USAGE IN INTERRUPT SERVICE ROUTINE TO ACCESS

TX/RX BUFFERS

; Request Configuration mode.

MOVLW B’10000000’ ; Set to Configuration Mode.

MOVWF CANCON

; A request to switch to Configuration mode may not be immediately honored.

; Module will wait for CAN bus to be idle before switching to Configuration Mode.

; Request for other modes such as Loopback, Disable etc. may be honored immediately.

; It is always good practice to wait and verify before continuing.

ConfigWait:

MOVF CANSTAT, W ; Read current mode state.

ANDLW B’10000000’ ; Interested in OPMODE bits only.

TSTFSZ WREG ; Is it Configuration mode yet?

BRA ConfigWait ; No. Continue to wait...

; Module is in Configuration mode now.

; Modify configuration registers as required.

; Switch back to Normal mode to be able to communicate.

; Save application required context.

; Poll interrupt flags and determine source of interrupt

; This was found to be CAN interrupt

; TempCANCON and TempCANSTAT are variables defined in Access Bank low

MOVFF CANCON, TempCANCON ; Save CANCON.WIN bits

; This is required to prevent CANCON

; from corrupting CAN buffer access

; in-progress while this interrupt

; occurred

MOVFF CANSTAT, TempCANSTAT ; Save CANSTAT register

; This is required to make sure that

; we use same CANSTAT value rather

; than one changed by another CAN

; interrupt.

MOVF TempCANSTAT, W ; Retrieve ICODE bits

ANDLW B’00001110’

ADDWF PCL, F ; Perform computed GOTO

; to corresponding interrupt cause

BRA NoInterrupt ; 000 = No interrupt

BRA ErrorInterrupt ; 001 = Error interrupt

BRA TXB2Interrupt ; 010 = TXB2 interrupt

BRA TXB1Interrupt ; 011 = TXB1 interrupt

BRA TXB0Interrupt ; 100 = TXB0 interrupt

BRA RXB1Interrupt ; 101 = RXB1 interrupt

BRA RXB0Interrupt ; 110 = RXB0 interrupt

; 111 = Wake-up on interrupt

WakeupInterrupt

BCF PIR3, WAKIF ; Clear the interrupt flag

;

; User code to handle wake-up procedure

;

; Continue checking for other interrupt source or return from here

…

NoInterrupt

… ; PC should never vector here. User may

; place a trap such as infinite loop or pin/port

; indication to catch this error.

PIC18F2585/2680/4585/4680

EXAMPLE 23-2: WIN AND ICODE BITS USAGE IN INTERRUPT SERVICE ROUTINE TO ACCESS

TX/RX BUFFERS (CONTINUED)

ErrorInterrupt

BCF PIR3, ERRIF ; Clear the interrupt flag

… ; Handle error.

RETFIE

TXB2Interrupt

BCF PIR3, TXB2IF ; Clear the interrupt flag

GOTO AccessBuffer

TXB1Interrupt

BCF PIR3, TXB1IF ; Clear the interrupt flag

GOTO AccessBuffer

TXB0Interrupt

BCF PIR3, TXB0IF ; Clear the interrupt flag

GOTO AccessBuffer

RXB1Interrupt

BCF PIR3, RXB1IF ; Clear the interrupt flag

GOTO Accessbuffer

RXB0Interrupt

BCF PIR3, RXB0IF ; Clear the interrupt flag

GOTO AccessBuffer

AccessBuffer ; This is either TX or RX interrupt

; Copy CANSTAT.ICODE bits to CANCON.WIN bits

MOVF TempCANCON, W ; Clear CANCON.WIN bits before copying

; new ones.

ANDLW B’11110001’ ; Use previously saved CANCON value to

; make sure same value.

MOVWF TempCANCON ; Copy masked value back to TempCANCON

MOVF TempCANSTAT, W ; Retrieve ICODE bits

ANDLW B’00001110’ ; Use previously saved CANSTAT value

; to make sure same value.

IORWF TempCANCON ; Copy ICODE bits to WIN bits.

MOVFF TempCANCON, CANCON ; Copy the result to actual CANCON

; Access current buffer…

; User code

; Restore CANCON.WIN bits

MOVF CANCON, W ; Preserve current non WIN bits

ANDLW B’11110001’

IORWF TempCANCON ; Restore original WIN bits

; Do not need to restore CANSTAT - it is read-only register.

; Return from interrupt or check for another module interrupt source

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 R/W-0

MDSEL1(1) MDSEL0(1) FIFOWM(2) EWIN4 EWIN3 EWIN2 EWIN1 EWIN0

bit 7 bit 0

bit 7-6 MDSEL1:MDSEL0: Mode Select bits(1)

00 = Legacy mode (Mode 0, default)

01 = Enhanced Legacy mode (Mode 1)

10 = Enhanced FIFO mode (Mode 2)

11 = Reserved

bit 5 FIFOWM: FIFO High Water Mark bit(2)

1 = Will cause FIFO interrupt when one receive buffer remains(3)

0 = Will cause FIFO interrupt when four receive buffers remain

bit 4-0 EWIN4:EWIN0: Enhanced Window Address bits

These bits map the group of 16 banked CAN SFRs into access bank addresses 0F60-0F6Dh.

Exact group of registers to map is determined by binary value of these bits.

Mode 0:

Unimplemented: Read as ‘0’

Mode 1, 2:

00000 = Acceptance Filters 0, 1, 2 and BRGCON2, 3

00001 = Acceptance Filters 3, 4, 5 and BRGCON1, CIOCON

00010 = Acceptance Filter Masks, Error and Interrupt Control

00011 = Transmit Buffer 0

00100 = Transmit Buffer 1

00101 = Transmit Buffer 2

00110 = Acceptance Filters 6, 7, 8

00111 = Acceptance Filters 9, 10, 11

01000 = Acceptance Filters 12, 13, 14

01001 = Acceptance Filters 15

01010-01110 = Reserved

01111 = RXINT0, RXINT1

10000 = Receive Buffer 0

10001 = Receive Buffer 1

10010 = TX/RX Buffer 0

10011 = TX/RX Buffer 1

10100 = TX/RX Buffer 2

10101 = TX/RX Buffer 3

10110 = TX/RX Buffer 4

10111 = TX/RX Buffer 5

11000-11111 = Reserved

Note 1: These bits can only be changed in Configuration mode. See Register 23-1 to

change to Configuration mode.

2: This bit is used in Mode 2 only.

3: FIFO length of 4 or less will cause this bit to be set.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/C-0 R/C-0 R-0 R-0 R-0 R-0 R-0 R-0

RXB0OVFL RXB1OVFL TXBO TXBP RXBP TXWARN RXWARN EWARN

Mode 1 R/C-0 R/C-0 R-0 R-0 R-0 R-0 R-0 R-0

— RXBnOVFL TXB0 TXBP RXBP TXWARN RXWARN EWARN

Mode 2 R/C-0 R/C-0 R-0 R-0 R-0 R-0 R-0 R-0

FIFOEMPTY RXBnOVFL TXBO TXBP RXBP TXWARN RXWARN EWARN

bit 7 bit 0

bit 7 Mode 0:

RXB0OVFL: Receive Buffer 0 Overflow bit

1 = Receive Buffer 0 overflowed

0 = Receive Buffer 0 has not overflowed

Mode 1:

Unimplemented: Read as ‘0’

Mode 2:

FIFOEMPTY: FIFO Not Empty bit

1 = Receive FIFO is not empty

0 = Receive FIFO is empty

bit 6 Mode 0:

RXB1OVFL: Receive Buffer 1 Overflow bit

1 = Receive Buffer 1 overflowed

0 = Receive Buffer 1 has not overflowed

Mode 1, 2:

RXBnOVFL: Receive Buffer n Overflow bit

1 = Receive Buffer n has overflowed

0 = Receive Buffer n has not overflowed

bit 5 TXBO: Transmitter Bus-Off bit

1 = Transmit error counter > 255

0 = Transmit error counter ≤ 255

bit 4 TXBP: Transmitter Bus Passive bit

1 = Transmit error counter > 127

0 = Transmit error counter ≤ 127

bit 3 RXBP: Receiver Bus Passive bit

1 = Receive error counter > 127

0 = Receive error counter ≤ 127

bit 2 TXWARN: Transmitter Warning bit

1 = Transmit error counter > 95

0 = Transmit error counter ≤ 95

bit 1 RXWARN: Receiver Warning bit

1 = 127 ≥ Receive error counter > 95

0 = Receive error counter ≤ 95

bit 0 EWARN: Error Warning bit

This bit is a flag of the RXWARN and TXWARN bits.

1 = The RXWARN or the TXWARN bits are set

0 = Neither the RXWARN or the TXWARN bits are set

Legend:

C = Clearable bit R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

23.2.2 DEDICATED CAN TRANSMIT

BUFFER REGISTERS

This section describes the dedicated CAN Transmit

Buffer registers and their associated control registers.

Mode 0 R/C-0 R-0 R-0 R-0 R/W-0 U-0 R/W-0 R/W-0

TXBIF TXABT(1) TXLARB(1) TXERR(1) TXREQ(2) — TXPRI1(3) TXPRI0(3)

Mode 1, 2 R/C-0 R-0 R-0 R-0 R/W-0 U-0 R/W-0 R/W-0

TXBIF TXABT(1) TXLARB(1) TXERR(1) TXREQ(2) — TXPRI1(3) TXPRI0(3)

bit 7 bit 0

bit 7 TXBIF: Transmit Buffer Interrupt Flag bit

1 = Transmit buffer has completed transmission of message and may be reloaded

0 = Transmit buffer has not completed transmission of a message

bit 6 TXABT: Transmission Aborted Status bit(1)

1 = Message was aborted

0 = Message was not aborted

bit 5 TXLARB: Transmission Lost Arbitration Status bit(1)

1 = Message lost arbitration while being sent

0 = Message did not lose arbitration while being sent

bit 4 TXERR: Transmission Error Detected Status bit(1)

1 = A bus error occurred while the message was being sent

0 = A bus error did not occur while the message was being sent

bit 3 TXREQ: Transmit Request Status bit(2)

1 = Requests sending a message. Clears the TXABT, TXLARB and TXERR bits.

0 = Automatically cleared when the message is successfully sent

bit 2 Unimplemented: Read as ‘0’

bit 1-0 TXPRI1:TXPRI0: Transmit Priority bits(3)

11 = Priority Level 3 (highest priority)

10 = Priority Level 2

01 = Priority Level 1

00 = Priority Level 0 (lowest priority)

Note 1: This bit is automatically cleared when TXREQ is set.

2: While TXREQ is set, Transmit Buffer registers remain read-only. Clearing this bit in

software while the bit is set will request a message abort.

3: These bits define the order in which transmit buffers will be transferred. They do not alter

the CAN message identifier.

Legend:

C = Clearable bit R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

HIGH BYTE [0 ≤ n ≤ 2]

LOW BYTE [0 ≤ n ≤ 2]

HIGH BYTE [0 ≤ n ≤ 2]

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier bits (if EXIDE (TXBnSIDL<3>) = 0)

Extended Identifier bits EID28:EID21 (if EXIDE = 1).

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x U-0 R/W-x U-0 R/W-x R/W-x

SID2 SID1 SID0 — EXIDE —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier bits (if EXIDE (TXBnSIDL<3>) = 0)

Extended Identifier bits EID20:EID18 (if EXIDE = 1).

bit 4 Unimplemented: Read as ‘0’

bit 3 EXIDE: Extended Identifier Enable bit

1 = Message will transmit extended ID, SID10:SID0 become EID28:EID18

0 = Message will transmit standard ID, EID17:EID0 are ignored

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier bits (not used when transmitting standard identifier message)

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

LOW BYTE [0 ≤ n ≤ 2]

[0 ≤ n ≤ 2, 0 ≤ m ≤ 7]

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier bits (not used when transmitting standard identifier message)

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

TXBnDm7 TXBnDm6 TXBnDm5 TXBnDm4 TXBnDm3 TXBnDm2 TXBnDm1 TXBnDm0

bit 7 bit 0

bit 7-0 TXBnDm7:TXBnDm0: Transmit Buffer n Data Field Byte m bits (where 0 ≤ n < 3 and 0 ≤ m < 8)

Each transmit buffer has an array of registers. For example, Transmit Buffer 0 has 7 registers:

TXB0D0 to TXB0D7.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

U-0 R/W-x U-0 U-0 R/W-x R/W-x R/W-x R/W-x

—TXRTR—— DLC3 DLC2 DLC1 DLC0

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6 TXRTR: Transmit Remote Frame Transmission Request bit

1 = Transmitted message will have TXRTR bit set

0 = Transmitted message will have TXRTR bit cleared

bit 5-4 Unimplemented: Read as ‘0’

bit 3-0 DLC3:DLC0: Data Length Code bits

1111 = Reserved

1110 = Reserved

1101 = Reserved

1100 = Reserved

1011 = Reserved

1010 = Reserved

1001 = Reserved

1000 = Data length = 8 bytes

0111 = Data length = 7 bytes

0110 = Data length = 6 bytes

0101 = Data length = 5 bytes

0100 = Data length = 4 bytes

0011 = Data length = 3 bytes

0010 = Data length = 2 bytes

0001 = Data length = 1 bytes

0000 = Data length = 0 bytes

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0

TEC7 TEC6 TEC5 TEC4 TEC3 TEC2 TEC1 TEC0

bit 7 bit 0

bit 7-0 TEC7:TEC0: Transmit Error Counter bits

This register contains a value which is derived from the rate at which errors occur. When the

error count overflows, the bus-off state occurs. When the bus has 128 occurrences of

11 consecutive recessive bits, the counter value is cleared.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

EXAMPLE 23-3: TRANSMITTING A CAN MESSAGE USING BANKED METHOD

EXAMPLE 23-4: TRANSMITTING A CAN MESSAGE USING WIN BITS

; Need to transmit Standard Identifier message 123h using TXB0 buffer.

; To successfully transmit, CAN module must be either in Normal or Loopback mode.

; TXB0 buffer is not in access bank. And since we want banked method, we need to make sure

; that correct bank is selected.

BANKSEL TXB0CON ; One BANKSEL in beginning will make sure that we are

; in correct bank for rest of the buffer access.

; Now load transmit data into TXB0 buffer.

MOVLW MY_DATA_BYTE1 ; Load first data byte into buffer

MOVWF TXB0D0 ; Compiler will automatically set “BANKED” bit

; Load rest of data bytes - up to 8 bytes into TXB0 buffer.

...

; Load message identifier

MOVLW 60H ; Load SID2:SID0, EXIDE = 0

MOVWF TXB0SIDL

MOVLW 24H ; Load SID10:SID3

MOVWF TXB0SIDH

; No need to load TXB0EIDL:TXB0EIDH, as we are transmitting Standard Identifier Message only.

; Now that all data bytes are loaded, mark it for transmission.

MOVLW B’00001000’ ; Normal priority; Request transmission

MOVWF TXB0CON

; If required, wait for message to get transmitted

BTFSC TXB0CON, TXREQ ; Is it transmitted?

BRA $-2 ; No. Continue to wait...

; Message is transmitted.

; Need to transmit Standard Identifier message 123h using TXB0 buffer.

; To successfully transmit, CAN module must be either in Normal or Loopback mode.

; TXB0 buffer is not in access bank. Use WIN bits to map it to RXB0 area.

MOVF CANCON, W ; WIN bits are in lower 4 bits only. Read CANCON

; register to preserve all other bits. If operation

; mode is already known, there is no need to preserve

; other bits.

ANDLW B’11110000’ ; Clear WIN bits.

IORLW B’00001000’ ; Select Transmit Buffer 0

MOVWF CANCON ; Apply the changes.

; Now TXB0 is mapped in place of RXB0. All future access to RXB0 registers will actually

; yield TXB0 register values.

; Load transmit data into TXB0 buffer.

MOVLW MY_DATA_BYTE1 ; Load first data byte into buffer

MOVWF RXB0D0 ; Access TXB0D0 via RXB0D0 address.

; Load rest of the data bytes - up to 8 bytes into “TXB0” buffer using RXB0 registers.

...

; Load message identifier

MOVLW 60H ; Load SID2:SID0, EXIDE = 0

MOVWF RXB0SIDL

MOVLW 24H ; Load SID10:SID3

MOVWF RXB0SIDH

; No need to load RXB0EIDL:RXB0EIDH, as we are transmitting Standard Identifier Message only.

; Now that all data bytes are loaded, mark it for transmission.

MOVLW B’00001000’ ; Normal priority; Request transmission

MOVWF RXB0CON

; If required, wait for message to get transmitted

BTFSC RXB0CON, TXREQ ; Is it transmitted?

BRA $-2 ; No. Continue to wait...

; Message is transmitted.

; If required, reset the WIN bits to default state.

PIC18F2585/2680/4585/4680

23.2.3 DEDICATED CAN RECEIVE

BUFFER REGISTERS

This section shows the dedicated CAN Receive Buffer

registers with their associated control registers.

Mode 0 R/C-0 R/W-0 R/W-0 U-0 R-0 R/W-0 R-0 R-0

RXFUL(1) RXM1 RXM0 — RXRTRRO RXB0DBEN JTOFF(2) FILHIT0

Mode 1, 2 R/C-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

RXFUL(1) RXM1 RTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0

bit 7 bit 0

bit 7 RXFUL: Receive Full Status bit(1)

1 = Receive buffer contains a received message

0 = Receive buffer is open to receive a new message

bit 6 Mode 0:

RXM1: Receive Buffer Mode bit 1

Combines with RXM0 to form RXM<1:0> bits (see bit 5).

11 = Receive all messages (including those with errors); filter criteria is ignored

10 = Receive only valid messages with extended identifier; EXIDEN in RXFnSIDL must be ‘1’

01 = Receive only valid messages with standard identifier; EXIDEN in RXFnSIDL must be ‘0’

00 = Receive all valid messages as per EXIDEN bit in RXFnSIDL register

Mode 1, 2:

RXM1: Receive Buffer Mode bit 1

1 = Receive all messages (including those with errors); acceptance filters are ignored

0 = Receive all valid messages as per acceptance filters

bit 5 Mode 0:

RXM0: Receive Buffer Mode bit 0

Combines with RXM1 to form RXM<1:0> bits (see bit 6).

Mode 1, 2:

RTRRO: Remote Transmission Request bit for Received Message (read-only)

1 = A remote transmission request is received

0 = A remote transmission request is not received

bit 4 Mode 0:

Unimplemented: Read as ‘0’

Mode 1, 2:

FILHIT4: Filter Hit bit 4

This bit combines with other bits to form filter acceptance bits <4:0>.

bit 3 Mode 0:

RXRTRRO: Remote Transmission Request bit for Received Message (read-only)

1 = A remote transmission request is received

0 = A remote transmission request is not received

Mode 1, 2:

FILHIT3: Filter Hit bit 3

This bit combines with other bits to form filter acceptance bits <4:0>.

PIC18F2585/2680/4585/4680

bit 2 Mode 0:

RXB0DBEN: Receive Buffer 0 Double-Buffer Enable bit

1 = Receive Buffer 0 overflow will write to Receive Buffer 1

0 = No Receive Buffer 0 overflow to Receive Buffer 1

Mode 1, 2:

FILHIT2: Filter Hit bit 2

This bit combines with other bits to form filter acceptance bits <4:0>.

bit 1 Mode 0:

JTOFF: Jump Table Offset bit (read-only copy of RXB0DBEN)(2)

1 = Allows jump table offset between 6 and 7

0 = Allows jump table offset between 1 and 0

Mode 1, 2:

FILHIT1: Filter Hit bit 1

This bit combines with other bits to form filter acceptance bits <4:0>.

bit 0 Mode 0:

FILHIT0: Filter Hit bit 0

This bit indicates which acceptance filter enabled the message reception into Receive Buffer 0.

1 = Acceptance Filter 1 (RXF1)

0 = Acceptance Filter 0 (RXF0)

Mode 1, 2:

FILHIT0: Filter Hit bit 0

This bit, in combination with FILHIT<4:1>, indicates which acceptance filter enabled the

message reception into this receive buffer.

01111 = Acceptance Filter 15 (RXF15)

01110 = Acceptance Filter 14 (RXF14)

...

00000 = Acceptance Filter 0 (RXF0)

Note 1: This bit is set by the CAN module upon receiving a message and must be cleared

by software after the buffer is read. As long as RXFUL is set, no new message will

be loaded and buffer will be considered full. After clearing the RXFUL flag, the PIR3

bit, RXB0IF, can be cleared. If RXB0IF is cleared, but RXFUL is not cleared, then

RXB0IF is set again.

2: This bit allows same filter jump table for both RXB0CON and RXB1CON.

Legend:

C = Clearable bit R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/C-0 R/W-0 R/W-0 U-0 R-0 R/W-0 R-0 R-0

RXFUL(1) RXM1 RXM0 — RXRTRRO FILHIT2 FILHIT1 FILHIT0

Mode 1, 2 R/C-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

RXFUL(1) RXM1 RTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0

bit 7 bit 0

bit 7 RXFUL: Receive Full Status bit(1)

1 = Receive buffer contains a received message

0 = Receive buffer is open to receive a new message

Note 1: This bit is set by the CAN module upon receiving a message and must be cleared

by software after the buffer is read. As long as RXFUL is set, no new message will

be loaded and buffer will be considered full.

bit 6 Mode 0:

RXM1: Receive Buffer Mode bit 1

Combines with RXM0 to form RXM<1:0> bits (see bit 5).

11 = Receive all messages (including those with errors); filter criteria is ignored

10 = Receive only valid messages with extended identifier; EXIDEN in RXFnSIDL must be ‘1’

01 = Receive only valid messages with standard identifier, EXIDEN in RXFnSIDL must be ‘0’

00 = Receive all valid messages as per EXIDEN bit in RXFnSIDL register

Mode 1, 2:

RXM1: Receive Buffer Mode bit

1 = Receive all messages (including those with errors); acceptance filters are ignored

0 = Receive all valid messages as per acceptance filters

bit 5 Mode 0:

RXM0: Receive Buffer Mode bit 0

Combines with RXM1 to form RXM<1:0> bits (see bit 6).

Mode 1, 2:

RTRRO: Remote Transmission Request bit for Received Message (read-only)

1 = A remote transmission request is received

0 = A remote transmission request is not received

bit 4 Mode 0:

Unimplemented: Read as ‘0’

Mode 1, 2:

FILHIT4: Filter Hit bit 4

This bit combines with other bits to form filter acceptance bits <4:0>.

bit 3 Mode 0:

RXRTRRO: Remote Transmission Request bit for Received Message (read-only)

1 = A remote transmission request is received

0 = A remote transmission request is not received

Mode 1, 2:

FILHIT3: Filter Hit bit 3

This bit combines with other bits to form filter acceptance bits <4:0>.

PIC18F2585/2680/4585/4680

HIGH BYTE [0 ≤ n ≤ 1]

bit 2-0 Mode 0:

FILHIT2:FILHIT0: Filter Hit bits

These bits indicate which acceptance filter enabled the last message reception into

Receive Buffer 1.

111 = Reserved

110 = Reserved

101 = Acceptance Filter 5 (RXF5)

100 = Acceptance Filter 4 (RXF4)

011 = Acceptance Filter 3 (RXF3)

010 = Acceptance Filter 2 (RXF2)

001 = Acceptance Filter 1 (RXF1), only possible when RXB0DBEN bit is set

000 = Acceptance Filter 0 (RXF0), only possible when RXB0DBEN bit is set

Mode 1, 2:

FILHIT2:FILHIT0 Filter Hit bits <2:0>

These bits, in combination with FILHIT<4:3>, indicate which acceptance filter enabled the

message reception into this receive buffer.

01111 = Acceptance Filter 15 (RXF15)

01110 = Acceptance Filter 14 (RXF14)

...

00000 = Acceptance Filter 0 (RXF0)

Legend:

C = Clearable bit R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-x R-x R-x R-x R-x R-x R-x R-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier bits (if EXID (RXBnSIDL<3>) = 0)

Extended Identifier bits EID28:EID21 (if EXID = 1).

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

LOW BYTE [0 ≤ n ≤ 1]

HIGH BYTE [0 ≤ n ≤ 1]

LOW BYTE [0 ≤ n ≤ 1]

R-x R-x R-x R-x R-x U-0 R-x R-x

SID2 SID1 SID0 SRR EXID —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier bits (if EXID = 0)

Extended Identifier bits EID20:EID18 (if EXID = 1).

bit 4 SRR: Substitute Remote Request bit

This bit is always ‘0’ when EXID = 1 or equal to the value of RXRTRRO (RBXnCON<3>) when

EXID = 0.

bit 3 EXID: Extended Identifier bit

1 = Received message is an extended data frame, SID10:SID0 are EID28:EID18

0 = Received message is a standard data frame

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-x R-x R-x R-x R-x R-x R-x R-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-x R-x R-x R-x R-x R-x R-x R-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

[0 ≤ n ≤ 1, 0 ≤ m ≤ 7]

U-0 R-x R-x R-x R-x R-x R-x R-x

— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6 RXRTR: Receiver Remote Transmission Request bit

1 = Remote transfer request

0 = No remote transfer request

bit 5 RB1: Reserved bit 1

Reserved by CAN Spec and read as ‘0’.

bit 4 RB0: Reserved bit 0

Reserved by CAN Spec and read as ‘0’.

bit 3-0 DLC3:DLC0: Data Length Code bits

1111 = Invalid

1110 = Invalid

1101 = Invalid

1100 = Invalid

1011 = Invalid

1010 = Invalid

1001 = Invalid

1000 = Data length = 8 bytes

0111 = Data length = 7 bytes

0110 = Data length = 6 bytes

0101 = Data length = 5 bytes

0100 = Data length = 4 bytes

0011 = Data length = 3 bytes

0010 = Data length = 2 bytes

0001 = Data length = 1 bytes

0000 = Data length = 0 bytes

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-x R-x R-x R-x R-x R-x R-x R-x

RXBnDm7 RXBnDm6 RXBnDm5 RXBnDm4 RXBnDm3 RXBnDm2 RXBnDm1 RXBnDm0

bit 7 bit 0

bit 7-0 RXBnDm7:RXBnDm0: Receive Buffer n Data Field Byte m bits (where 0 ≤ n < 1 and 0 < m < 7)

Each receive buffer has an array of registers. For example, Receive Buffer 0 has 8 registers:

RXB0D0 to RXB0D7.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

EXAMPLE 23-5: READING A CAN MESSAGE

R-0 R-0 R-0 R-0 R-0 R-0 R-0 R-0

REC7 REC6 REC5 REC4 REC3 REC2 REC1 REC0

bit 7 bit 0

bit 7-0 REC7:REC0: Receive Error Counter bits

This register contains the receive error value as defined by the CAN specifications.

When RXERRCNT > 127, the module will go into an error-passive state. RXERRCNT does not

have the ability to put the module in “bus-off” state.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

; Need to read a pending message from RXB0 buffer.

; To receive any message, filter, mask and RXM1:RXM0 bits in RXB0CON registers must be

; programmed correctly.

;

; Make sure that there is a message pending in RXB0.

BTFSS RXB0CON, RXFUL ; Does RXB0 contain a message?

BRA NoMessage ; No. Handle this situation...

; We have verified that a message is pending in RXB0 buffer.

; If this buffer can receive both Standard or Extended Identifier messages,

; identify type of message received.

BTFSS RXB0SIDL, EXID ; Is this Extended Identifier?

BRA StandardMessage ; No. This is Standard Identifier message.

; Yes. This is Extended Identifier message.

; Read all 29-bits of Extended Identifier message.

...

; Now read all data bytes

MOVFF RXB0DO, MY_DATA_BYTE1

...

; Once entire message is read, mark the RXB0 that it is read and no longer FULL.

BCF RXB0CON, RXFUL ; This will allow CAN Module to load new messages

; into this buffer.

...

PIC18F2585/2680/4585/4680

23.2.3.1 Programmable TX/RX and

Auto-RTR Buffers

The ECAN module contains 6 message buffers that can

be programmed as transmit or receive buffers. Any of

these buffers can also be programmed to automatically

handle RTR messages.

[0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 0](1)

Note: These registers are not used in Mode 0.

R/W-0 R/W-0 R-0 R-0 R-0 R-0 R-0 R-0

RXFUL(2) RXM1 RXRTRRO FILHIT4 FILHIT3 FILHIT2 FILHIT1 FILHIT0

bit 7 bit 0

bit 7 RXFUL: Receive Full Status bit(2)

1 = Receive buffer contains a received message

0 = Receive buffer is open to receive a new message

bit 6 RXM1: Receive Buffer Mode bit

1 = Receive all messages including partial and invalid (acceptance filters are ignored)

0 = Receive all valid messages as per acceptance filters

bit 5 RXRTRRO: Read-Only Remote Transmission Request for Received Message bit

1 = Received message is a remote transmission request

0 = Received message is not a remote transmission request

bit 4-0 FILHIT4:FILHIT0: Filter Hit bits

These bits indicate which acceptance filter enabled the last message reception into this buffer.

01111 = Acceptance Filter 15 (RXF15)

01110 = Acceptance Filter 14 (RXF14)

...

00001 = Acceptance Filter 1 (RXF1)

00000 = Acceptance Filter 0 (RXF0)

Note 1: These registers are available in Mode 1 and 2 only.

2: This bit is set by the CAN module upon receiving a message and must be cleared

by software after the buffer is read. As long as RXFUL is set, no new message will

be loaded and the buffer will be considered full.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

[0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 1](1)

R/W-0 R-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0

TXBIF TXABT TXLARB TXERR TXREQ RTREN TXPRI1 TXPRI0

bit 7 bit 0

bit 7 TXBIF: Transmit Buffer Interrupt Flag bit(3)

1 = A message is successfully transmitted

0 = No message was transmitted

bit 6 TXABT: Transmission Aborted Status bit(3)

1 = Message was aborted

0 = Message was not aborted

bit 5 TXLARB: Transmission Lost Arbitration Status bit(3)

1 = Message lost arbitration while being sent

0 = Message did not lose arbitration while being sent

bit 4 TXERR: Transmission Error Detected Status bit(3)

1 = A bus error occurred while the message was being sent

0 = A bus error did not occur while the message was being sent

bit 3 TXREQ: Transmit Request Status bit(2,4)

1 = Requests sending a message; clears the TXABT, TXLARB and TXERR bits

0 = Automatically cleared when the message is successfully sent

bit 2 RTREN: Automatic Remote Transmission Request Enable bit

1 = When a remote transmission request is received, TXREQ will be automatically set

0 = When a remote transmission request is received, TXREQ will be unaffected

bit 1-0 TXPRI1:TXPRI0: Transmit Priority bits(5)

11 = Priority Level 3 (highest priority)

10 = Priority Level 2

01 = Priority Level 1

00 = Priority Level 0 (lowest priority)

Note 1: These registers are available in Mode 1 and 2 only.

2: Clearing this bit in software while the bit is set will request a message abort.

3: This bit is automatically cleared when TXREQ is set.

4: While TXREQ is set or transmission is in progress, transmit buffer registers remain

read-only.

5: These bits set the order in which the transmit buffer will be transferred. They do not

alter the CAN message identifier.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

HIGH BYTE IN RECEIVE MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 0](1)

HIGH BYTE IN TRANSMIT MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 1](1)

R-x R-x R-x R-x R-x R-x R-x R-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier bits (if EXIDE (BnSIDL<3>) = 0)

Extended Identifier bits EID28:EID21 (if EXIDE = 1).

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier bits (if EXIDE (BnSIDL<3>) = 0)

Extended Identifier bits EID28:EID21 (if EXIDE = 1).

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

LOW BYTE IN RECEIVE MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 0](1)

LOW BYTE IN TRANSMIT MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 1](1)

R-x R-x R-x R-x R-x U-0 R-x R-x

SID2 SID1 SID0 SRR EXID —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier bits (if EXID = 0)

Extended Identifier bits EID20:EID18 (if EXID = 1).

bit 4 SRR: Substitute Remote Transmission Request bit (only when EXID = 1)

1 = Remote transmission request occurred

0 = No remote transmission request occurred

bit 3 EXID: Extended Identifier Enable bit

1 = Received message is an extended identifier frame (SID10:SID0 are EID28:EID18)

0 = Received message is a standard identifier frame

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x U-0 R/W-x U-0 R/W-x R/W-x

SID2 SID1 SID0 — EXIDE —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier bits (if EXIDE = 0)

Extended Identifier bits EID20:EID18 (if EXIDE = 1).

bit 4 Unimplemented: Read as ‘0’

bit 3 EXIDE: Extended Identifier Enable bit

1 = Received message is an extended identifier frame (SID10:SID0 are EID28:EID18)

0 = Received message is a standard identifier frame

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

HIGH BYTE IN RECEIVE MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 0](1)

HIGH BYTE IN TRANSMIT MODE [0 ≤ n ≤ 5, TXnEN (BSEL0<n>) = 1](1)

LOW BYTE IN RECEIVE MODE [0 ≤ n ≤ 5, TXnEN (BSEL<n>) = 0](1)

R-x R-x R-x R-x R-x R-x R-x R-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-x R-x R-x R-x R-x R-x R-x R-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

LOW BYTE IN TRANSMIT MODE [0 ≤ n ≤ 5, TXnEN (BSEL<n>) = 1](1)

[0 ≤ n ≤ 5, 0 ≤ m ≤ 7, TXnEN (BSEL<n>) = 0](1)

[0 ≤ n ≤ 5, 0 ≤ m ≤ 7, TXnEN (BSEL<n>) = 1](1)

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier bits

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R-xR-xR-xR-xR-xR-xR-xR-x

BnDm7 BnDm6 BnDm5 BnDm4 BnDm3 BnDm2 BnDm1 BnDm0

bit 7 bit 0

bit 7-0 BnDm7:BnDm0: Receive Buffer n Data Field Byte m bits (where 0 ≤ n < 3 and 0 < m < 8)

Each receive buffer has an array of registers. For example, Receive Buffer 0 has 7 registers:

B0D0 to B0D7.

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

BnDm7 BnDm6 BnDm5 BnDm4 BnDm3 BnDm2 BnDm1 BnDm0

bit 7 bit 0

bit 7-0 BnDm7:BnDm0: Transmit Buffer n Data Field Byte m bits (where 0 ≤ n < 3 and 0 < m < 8)

Each transmit buffer has an array of registers. For example, Transmit Buffer 0 has 7 registers:

TXB0D0 to TXB0D7.

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

[0 ≤ n ≤ 5, TXnEN (BSEL<n>) = 0](1)

U-0 R-x R-x R-x R-x R-x R-x R-x

— RXRTR RB1 RB0 DLC3 DLC2 DLC1 DLC0

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6 RXRTR: Receiver Remote Transmission Request bit

1 = This is a remote transmission request

0 = This is not a remote transmission request

bit 5 RB1: Reserved bit 1

Reserved by CAN Spec and read as ‘0’.

bit 4 RB0: Reserved bit 0

Reserved by CAN Spec and read as ‘0’.

bit 3-0 DLC3:DLC0: Data Length Code bits

1111 = Reserved

1110 = Reserved

1101 = Reserved

1100 = Reserved

1011 = Reserved

1010 = Reserved

1001 = Reserved

1000 = Data length = 8 bytes

0111 = Data length = 7 bytes

0110 = Data length = 6 bytes

0101 = Data length = 5 bytes

0100 = Data length = 4 bytes

0011 = Data length = 3 bytes

0010 = Data length = 2 bytes

0001 = Data length = 1 bytes

0000 = Data length = 0 bytes

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

[0 ≤ n ≤ 5, TXnEN (BSEL<n>) = 1](1)

U-0 R/W-x U-0 U-0 R/W-x R/W-x R/W-x R/W-x

—TXRTR—— DLC3 DLC2 DLC1 DLC0

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6 TXRTR: Transmitter Remote Transmission Request bit

1 = Transmitted message will have RTR bit set

0 = Transmitted message will have RTR bit cleared

bit 5-4 Unimplemented: Read as ‘0’

bit 3-0 DLC3:DLC0: Data Length Code bits

1111-1001 = Reserved

1000 = Data length = 8 bytes

0111 = Data length = 7 bytes

0110 = Data length = 6 bytes

0101 = Data length = 5 bytes

0100 = Data length = 4 bytes

0011 = Data length = 3 bytes

0010 = Data length = 2 bytes

0001 = Data length = 1 bytes

0000 = Data length = 0 bytes

Note 1: These registers are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0

B5TXEN B4TXEN B3TXEN B2TXEN B1TXEN B0TXEN — —

bit 7 bit 0

bit 7-2 B5TXEN:B0TXEN: Buffer 5 to Buffer 0 Transmit Enable bit

1 = Buffer is configured in Transmit mode

0 = Buffer is configured in Receive mode

bit 1-0 Unimplemented: Read as ‘0’

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

23.2.3.2 Message Acceptance Filters

and Masks

This section describes the message acceptance filters

and masks for the CAN receive buffers.

REGISTERS, HIGH BYTE [0 ≤ n ≤ 15](1)

REGISTERS, LOW BYTE [0 ≤ n ≤ 15](1)

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier Filter bits (if EXIDEN = 0)

Extended Identifier Filter bits EID28:EID21 (if EXIDEN = 1).

Note 1: Registers RXF6SIDH:RXF15SIDH are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x U-0 R/W-x U-0 R/W-x R/W-x

SID2 SID1 SID0 — EXIDEN(2) —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier Filter bits (if EXIDEN = 0)

Extended Identifier Filter bits EID20:EID18 (if EXIDEN = 1).

bit 4 Unimplemented: Read as ‘0’

bit 3 EXIDEN: Extended Identifier Filter Enable bit(2)

1 = Filter will only accept extended ID messages

0 = Filter will only accept standard ID messages

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier Filter bits

Note 1: Registers RXF6SIDL:RXF15SIDL are available in Mode 1 and 2 only.

2: In Mode 0, this bit must be set/cleared as required, irrespective of corresponding

mask register value.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

REGISTERS, HIGH BYTE [0 ≤ n ≤ 15](1)

REGISTERS, LOW BYTE [0 ≤ n ≤ 15](1)

REGISTERS, HIGH BYTE [0 ≤ n ≤ 1]

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier Filter bits

Note 1: Registers RXF6EIDH:RXF15EIDH are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier Filter bits

Note 1: Registers RXF6EIDL:RXF15EIDL are available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

SID10 SID9 SID8 SID7 SID6 SID5 SID4 SID3

bit 7 bit 0

bit 7-0 SID10:SID3: Standard Identifier Mask bits or Extended Identifier Mask bits EID28:EID21

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

REGISTERS, LOW BYTE [0 ≤ n ≤ 1]

REGISTERS, HIGH BYTE [0 ≤ n ≤ 1]

REGISTERS, LOW BYTE [0 ≤ n ≤ 1]

R/W-x R/W-x R/W-x U-0 R/W-0 U-0 R/W-x R/W-x

SID2 SID1 SID0 — EXIDEN(1) —EID17EID16

bit 7 bit 0

bit 7-5 SID2:SID0: Standard Identifier Mask bits or Extended Identifier Mask bits EID20:EID18

bit 4 Unimplemented: Read as ‘0’

bit 3 Mode 0:

Unimplemented: Read as ‘0’

Mode 1, 2:

EXIDEN: Extended Identifier Filter Enable Mask bit(1)

1 = Messages selected by the EXIDEN bit in RXFnSIDL will be accepted

0 = Both standard and extended identifier messages will be accepted

Note 1: This bit is available in Mode 1 and 2 only.

bit 2 Unimplemented: Read as ‘0’

bit 1-0 EID17:EID16: Extended Identifier Mask bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID15 EID14 EID13 EID12 EID11 EID10 EID9 EID8

bit 7 bit 0

bit 7-0 EID15:EID8: Extended Identifier Mask bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

EID7 EID6 EID5 EID4 EID3 EID2 EID1 EID0

bit 7 bit 0

bit 7-0 EID7:EID0: Extended Identifier Mask bits

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

RXFCON0 R/W-0 R/W-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

RXF7EN RXF6EN RXF5EN RXF4EN RXF3EN RXF2EN RXF1EN RXF0EN

RXFCON1 R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 R/W-0

RXF15EN RXF14EN RXF13EN RXF12EN RXF11EN RXF10EN RXF9EN RXF8EN

bit 7 bit 0

bit 7-0 RXFnEN: Receive Filter n Enable bits

0 = Filter is disabled

1 = Filter is enabled

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

Note: Registers 23-46 through 23-51are writable

in Configuration mode only.

U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

— — — FLC4FLC3FLC2FLC1FLC0

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-0 FLC4:FLC0: Filter Length Count bits

Mode 0:

Not used; forced to ‘00000’.

00000-10010 =018 bits are available for standard data byte filter. Actual number of bits

used depends on DLC3:DLC0 bits (RXBnDLC<3:0> or BnDLC<3:0> if

configured as RX buffer) of message being received.

If DLC3:DLC0 = 0000 No bits will be compared with incoming data bits

If DLC3:DLC0 = 0001 Up to 8 data bits of RXFnEID<7:0>, as determined by FLC2:FLC0, will

be compared with the corresponding number of data bits of the

incoming message

If DLC3:DLC0 = 0010 Up to 16 data bits of RXFnEID<15:0>, as determined by FLC3:FLC0,

will be compared with the corresponding number of data bits of the

incoming message

If DLC3:DLC0 = 0011 Up to 18 data bits of RXFnEID<17:0>, as determined by FLC4:FLC0,

will be compared with the corresponding number of data bits of the

incoming message

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

RXFBCON0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F1BP_3 F1BP_2 F1BP_1 F1BP_0 F0BP_3 F0BP_2 F0BP_1 F0BP_0

RXFBCON1 R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 R/W-1

F3BP_3 F3BP_2 F3BP_1 F3BP_0 F2BP_3 F2BP_2 F2BP_1 F2BP_0

RXFBCON2 R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 R/W-1

F5BP_3 F5BP_2 F5BP_1 F5BP_0 F4BP_3 F4BP_2 F4BP_1 F4BP_0

RXFBCON3 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F7BP_3 F7BP_2 F7BP_1 F7BP_0 F6BP_3 F6BP_2 F6BP_1 F6BP_0

RXFBCON4 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F9BP_3 F9BP_2 F9BP_1 F9BP_0 F8BP_3 F8BP_2 F8BP_1 F8BP_0

RXFBCON5 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F11BP_3 F11BP_2 F11BP_1 F11BP_0 F10BP_3 F10BP_2 F10BP_1 F10BP_0

RXFBCON6 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F13BP_3 F13BP_2 F13BP_1 F13BP_0 F12BP_3 F12BP_2 F12BP_1 F12BP_0

RXFBCON7 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

F15BP_3 F15BP_2 F15BP_1 F15BP_0 F14BP_3 F14BP_2 F14BP_1 F14BP_0

bit 7 bit 0

bit 7-0 FnBP_3:FnBP_0: Filter n Buffer Pointer Nibble bits

0000 = Filter n is associated with RXB0

0001 = Filter n is associated with RXB1

0010 = Filter n is associated with B0

0011 = Filter n is associated with B1

...

0111 = Filter n is associated with B5

1111-1000 = Reserved

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-1 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 R/W-0

FIL3_1 FIL3_0 FIL2_1 FIL2_0 FIL1_1 FIL1_0 FIL0_1 FIL0_0

bit 7 bit 0

bit 7-6 FIL3_1:FIL3_0: Filter 3 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 5-4 FIL2_1:FIL2_0: Filter 2 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 3-2 FIL1_1:FIL1_0: Filter 1 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 1-0 FIL0_1:FIL0_0: Filter 0 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-1 R/W-0 R/W-1

FIL7_1 FIL7_0 FIL6_1 FIL6_0 FIL5_1 FIL5_0 FIL4_1 FIL4_0

bit 7 bit 0

bit 7-6 FIL7_1:FIL7_0: Filter 7 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 5-4 FIL6_1:FIL6_0: Filter 6 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 3-2 FIL5_1:FIL5_0: Filter 5 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 1-0 FIL4_1:FIL4_0: Filter 4 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

FIL11_1 FIL11_0 FIL10_1 FIL10_0 FIL9_1 FIL9_0 FIL8_1 FIL8_0

bit 7 bit 0

bit 7-6 FIL11_1:FIL11_0: Filter 11 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 5-4 FIL10_1:FIL10_0: Filter 10 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 3-2 FIL9_1:FIL9_0: Filter 9 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 1-0 FIL8_1:FIL8_0: Filter 8 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

FIL15_1 FIL15_0 FIL14_1 FIL14_0 FIL13_1 FIL13_0 FIL12_1 FIL12_0

bit 7 bit 0

bit 7-6 FIL15_1:FIL15_0: Filter 15 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 5-4 FIL14_1:FIL14_0: Filter 14 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 3-2 FIL13_1:FIL13_0: Filter 13 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

bit 1-0 FIL12_1:FIL12_0: Filter 12 Select bits 1 and 0

11 = No mask

10 = Filter 15

01 = Acceptance Mask 1

00 = Acceptance Mask 0

Note 1: This register is available in Mode 1 and 2 only.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

23.2.4 CAN BAUD RATE REGISTERS

This section describes the CAN Baud Rate registers.

Note: These registers are writable in

Configuration mode only.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SJW1 SJW0 BRP5 BRP4 BRP3 BRP2 BRP1 BRP0

bit 7 bit 0

bit 7-6 SJW1:SJW0: Synchronized Jump Width bits

11 = Synchronization jump width time = 4 x TQ

10 = Synchronization jump width time = 3 x TQ

01 = Synchronization jump width time = 2 x TQ

00 = Synchronization jump width time = 1 x TQ

bit 5-0 BRP5:BRP0: Baud Rate Prescaler bits

111111 = TQ = (2 x 64)/FOSC

111110 = TQ = (2 x 63)/FOSC

000001 = TQ = (2 x 2)/FOSC

000000 = TQ = (2 x 1)/FOSC

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

SEG2PHTS SAM SEG1PH2 SEG1PH1 SEG1PH0 PRSEG2 PRSEG1 PRSEG0

bit 7 bit 0

bit 7 SEG2PHTS: Phase Segment 2 Time Select bit

1 = Freely programmable

0 = Maximum of PHEG1 or Information Processing Time (IPT), whichever is greater

bit 6 SAM: Sample of the CAN bus Line bit

1 = Bus line is sampled three times prior to the sample point

0 = Bus line is sampled once at the sample point

bit 5-3 SEG1PH2:SEG1PH0: Phase Segment 1 bits

111 = Phase Segment 1 time = 8 x TQ

110 = Phase Segment 1 time = 7 x TQ

101 = Phase Segment 1 time = 6 x TQ

100 = Phase Segment 1 time = 5 x TQ

011 = Phase Segment 1 time = 4 x TQ

010 = Phase Segment 1 time = 3 x TQ

001 = Phase Segment 1 time = 2 x TQ

000 = Phase Segment 1 time = 1 x TQ

bit 2-0 PRSEG2:PRSEG0: Propagation Time Select bits

111 = Propagation time = 8 x TQ

110 = Propagation time = 7 x TQ

101 = Propagation time = 6 x TQ

100 = Propagation time = 5 x TQ

011 = Propagation time = 4 x TQ

010 = Propagation time = 3 x TQ

001 = Propagation time = 2 x TQ

000 = Propagation time = 1 x TQ

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

R/W-0 R/W-0 U-0 U-0 U-0 R/W-0 R/W-0 R/W-0

WAKDIS WAKFIL — — — SEG2PH2(1) SEG2PH1(1) SEG2PH0(1)

bit 7 bit 0

bit 7 WAKDIS: Wake-up Disable bit

1 = Disable CAN bus activity wake-up feature

0 = Enable CAN bus activity wake-up feature

bit 6 WAKFIL: Selects CAN bus Line Filter for Wake-up bit

1 = Use CAN bus line filter for wake-up

0 = CAN bus line filter is not used for wake-up

bit 5-3 Unimplemented: Read as ‘0’

bit 2-0 SEG2PH2:SEG2PH0: Phase Segment 2 Time Select bits(1)

111 = Phase Segment 2 time = 8 x TQ

110 = Phase Segment 2 time = 7 x TQ

101 = Phase Segment 2 time = 6 x TQ

100 = Phase Segment 2 time = 5 x TQ

011 = Phase Segment 2 time = 4 x TQ

010 = Phase Segment 2 time = 3 x TQ

001 = Phase Segment 2 time = 2 x TQ

000 = Phase Segment 2 time = 1 x TQ

Note 1: Ignored if SEG2PHTS bit (BRGCON2<7>) is ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

- n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

23.2.5 CAN MODULE I/O CONTROL

This register controls the operation of the CAN module’s

I/O pins in relation to the rest of the microcontroller.

U-0 U-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0

—— ENDRHI(1) CANCAP — — — —

bit 7 bit 0

bit 7-6 Unimplemented: Read as ‘0’

bit 5 ENDRHI: Enable Drive High bit(1)

1 = CANTX pin will drive VDD when recessive

0 = CANTX pin will be tri-state when recessive

Note 1: Always set this bit when using differential bus to avoid signal crosstalk in CANTX

from other nearby pins.

bit 4 CANCAP: CAN Message Receive Capture Enable bit

1 = Enable CAN capture, CAN message receive signal replaces input on RC2/CCP1

0 = Disable CAN capture, RC2/CCP1 input to CCP1 module

bit 3-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

23.2.6 CAN INTERRUPT REGISTERS

The registers in this section are the same as described

in Section 9.0 “Interrupts”. They are duplicated here

for convenience.

Mode 0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIF WAKIF ERRIF TXB2IF TXB1IF(1) TXB0IF(1) RXB1IF RXB0IF

Mode 1, 2 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIF WAKIF ERRIF TXBnIF TXB1IF(1) TXB0IF(1) RXBnIF FIFOWMIF

bit 7 bit 0

bit 7 IRXIF: CAN Invalid Received Message Interrupt Flag bit

1 = An invalid message has occurred on the CAN bus

0 = No invalid message on CAN bus

bit 6 WAKIF: CAN bus Activity Wake-up Interrupt Flag bit

1 = Activity on CAN bus has occurred

0 = No activity on CAN bus

bit 5 ERRIF: CAN bus Error Interrupt Flag bit

1 = An error has occurred in the CAN module (multiple sources)

0 = No CAN module errors

bit 4 When CAN is in Mode 0:

TXB2IF: CAN Transmit Buffer 2 Interrupt Flag bit

1 = Transmit Buffer 2 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 2 has not completed transmission of a message

When CAN is in Mode 1 or 2:

TXBnIF: Any Transmit Buffer Interrupt Flag bit

1 = One or more transmit buffers have completed transmission of a message and may be reloaded

0 = No transmit buffer is ready for reload

bit 3 TXB1IF: CAN Transmit Buffer 1 Interrupt Flag bit(1)

1 = Transmit Buffer 1 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 1 has not completed transmission of a message

bit 2 TXB0IF: CAN Transmit Buffer 0 Interrupt Flag bit(1)

1 = Transmit Buffer 0 has completed transmission of a message and may be reloaded

0 = Transmit Buffer 0 has not completed transmission of a message

bit 1 When CAN is in Mode 0:

RXB1IF: CAN Receive Buffer 1 Interrupt Flag bit

1 = Receive Buffer 1 has received a new message

0 = Receive Buffer 1 has not received a new message

When CAN is in Mode 1 or 2:

RXBnIF: Any Receive Buffer Interrupt Flag bit

1 = One or more receive buffers has received a new message

0 = No receive buffer has received a new message

bit 0 When CAN is in Mode 0:

RXB0IF: CAN Receive Buffer 0 Interrupt Flag bit

1 = Receive Buffer 0 has received a new message

0 = Receive Buffer 0 has not received a new message

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIF: FIFO Watermark Interrupt Flag bit

1 = FIFO high watermark is reached

0 = FIFO high watermark is not reached

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIE WAKIE ERRIE TXB2IE TXB1IE(1) TXB0IE(1) RXB1IE RXB0IE

Mode 1, 2 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

IRXIE WAKIE ERRIE TXBnIE TXB1IE(1) TXB0IE(1) RXBnIE FIFOWMIE

bit 7 bit 0

bit 7 IRXIE: CAN Invalid Received Message Interrupt Enable bit

1 = Enable invalid message received interrupt

0 = Disable invalid message received interrupt

bit 6 WAKIE: CAN bus Activity Wake-up Interrupt Enable bit

1 = Enable bus activity wake-up interrupt

0 = Disable bus activity wake-up interrupt

bit 5 ERRIE: CAN bus Error Interrupt Enable bit

1 = Enable CAN bus error interrupt

0 = Disable CAN bus error interrupt

bit 4 When CAN is in Mode 0:

TXB2IE: CAN Transmit Buffer 2 Interrupt Enable bit

1 = Enable Transmit Buffer 2 interrupt

0 = Disable Transmit Buffer 2 interrupt

When CAN is in Mode 1 or 2:

TXBnIE: CAN Transmit Buffer Interrupts Enable bit

1 = Enable transmit buffer interrupt; individual interrupt is enabled by TXBIE and BIE0

0 = Disable all transmit buffer interrupts

bit 3 TXB1IE: CAN Transmit Buffer 1 Interrupt Enable bit(1)

1 = Enable Transmit Buffer 1 interrupt

0 = Disable Transmit Buffer 1 interrupt

bit 2 TXB0IE: CAN Transmit Buffer 0 Interrupt Enable bit(1)

1 = Enable Transmit Buffer 0 interrupt

0 = Disable Transmit Buffer 0 interrupt

bit 1 When CAN is in Mode 0:

RXB1IE: CAN Receive Buffer 1 Interrupt Enable bit

1 = Enable Receive Buffer 1 interrupt

0 = Disable Receive Buffer 1 interrupt

When CAN is in Mode 1 or 2:

RXBnIE: CAN Receive Buffer Interrupts Enable bit

1 = Enable receive buffer interrupt; individual interrupt is enabled by BIE0

0 = Disable all receive buffer interrupts

bit 0 When CAN is in Mode 0:

RXB0IE: CAN Receive Buffer 0 Interrupt Enable bit

1 = Enable Receive Buffer 0 interrupt

0 = Disable Receive Buffer 0 interrupt

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIE: FIFO Watermark Interrupt Enable bit

1 = Enable FIFO watermark interrupt

0 = Disable FIFO watermark interrupt

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

Mode 0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

IRXIP WAKIP ERRIP TXB2IP TXB1IP(1) TXB0IP(1) RXB1IP RXB0IP

Mode 1, 2 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

IRXIP WAKIP ERRIP TXBnIP TXB1IP(1) TXB0IP(1) RXBnIP FIFOWMIP

bit 7 bit 0

bit 7 IRXIP: CAN Invalid Received Message Interrupt Priority bit

1 = High priority

0 = Low priority

bit 6 WAKIP: CAN bus Activity Wake-up Interrupt Priority bit

1 = High priority

0 = Low priority

bit 5 ERRIP: CAN bus Error Interrupt Priority bit

1 = High priority

0 = Low priority

bit 4 When CAN is in Mode 0:

TXB2IP: CAN Transmit Buffer 2 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1 or 2:

TXBnIP: CAN Transmit Buffer Interrupt Priority bit

1 = High priority

0 = Low priority

bit 3 TXB1IP: CAN Transmit Buffer 1 Interrupt Priority bit(1)

1 = High priority

0 = Low priority

bit 2 TXB0IP: CAN Transmit Buffer 0 Interrupt Priority bit(1)

1 = High priority

0 = Low priority

bit 1 When CAN is in Mode 0:

RXB1IP: CAN Receive Buffer 1 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1 or 2:

RXBnIP: CAN Receive Buffer Interrupts Priority bit

1 = High priority

0 = Low priority

bit 0 When CAN is in Mode 0:

RXB0IP: CAN Receive Buffer 0 Interrupt Priority bit

1 = High priority

0 = Low priority

When CAN is in Mode 1:

Unimplemented: Read as ‘0’

When CAN is in Mode 2:

FIFOWMIP: FIFO Watermark Interrupt Priority bit

1 = High priority

0 = Low priority

Note 1: In CAN Mode 1 and 2, this bit is forced to ‘0’.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 U-0 U-0

——— TXB2IE(2) TXB1IE(2) TXB0IE(2) — —

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-2 TXB2IE:TXB0IE: Transmit Buffer 2-0 Interrupt Enable bit(2)

1 = Transmit buffer interrupt is enabled

0 = Transmit buffer interrupt is disabled

bit 1-0 Unimplemented: Read as ‘0’

Note 1: This register is available in Mode 1 and 2 only.

2: TXBnIE in PIE3 register must be set to get an interrupt.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

B5IE(2) B4IE(2) B3IE(2) B2IE(2) B1IE(2) B0IE(2) RXB1IE(2) RXB0IE(2)

bit 7 bit 0

bit 7-2 B5IE:B0IE: Programmable Transmit/Receive Buffer 5-0 Interrupt Enable bit(2)

1 = Interrupt is enabled

0 = Interrupt is disabled

bit 1-0 RXB1IE:RXB0IE: Dedicated Receive Buffer 1-0 Interrupt Enable bit(2)

1 = Interrupt is enabled

0 = Interrupt is disabled

Note 1: This register is available in Mode 1 and 2 only.

2: Either TXBnIE or RXBnIE in PIE3 register must be set to get an interrupt.

Legend:

R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’

-n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared x = Bit is unknown

PIC18F2585/2680/4585/4680

TABLE 23-1: CAN CONTROLLER REGISTER MAP

Address(1) Name Address Name Address Name Address Name

F7Fh SPBRGH(3) F5Fh CANCON_RO0 F3Fh CANCON_RO2 F1Fh RXM1EIDL

F7Eh BAUDCON(3) F5Eh CANSTAT_RO0 F3Eh CANSTAT_RO2 F1Eh RXM1EIDH

F7Dh —(4) F5Dh RXB1D7 F3Dh TXB1D7 F1Dh RXM1SIDL

F7Ch —(4) F5Ch RXB1D6 F3Ch TXB1D6 F1Ch RXM1SIDH

F7Bh —(4) F5Bh RXB1D5 F3Bh TXB1D5 F1Bh RXM0EIDL

F7Ah —(4) F5Ah RXB1D4 F3Ah TXB1D4 F1Ah RXM0EIDH

F79h ECCP1DEL(3) F59h RXB1D3 F39h TXB1D3 F19h RXM0SIDL

F78h —(4) F58h RXB1D2 F38h TXB1D2 F18h RXM0SIDH

F77h ECANCON F57h RXB1D1 F37h TXB1D1 F17h RXF5EIDL

F76h TXERRCNT F56h RXB1D0 F36h TXB1D0 F16h RXF5EIDH

F75h RXERRCNT F55h RXB1DLC F35h TXB1DLC F15h RXF5SIDL

F74h COMSTAT F54h RXB1EIDL F34h TXB1EIDL F14h RXF5SIDH

F73h CIOCON F53h RXB1EIDH F33h TXB1EIDH F13h RXF4EIDL

F72h BRGCON3 F52h RXB1SIDL F32h TXB1SIDL F12h RXF4EIDH

F71h BRGCON2 F51h RXB1SIDH F31h TXB1SIDH F11h RXF4SIDL

F70h BRGCON1 F50h RXB1CON F30h TXB1CON F10h RXF4SIDH

F6Fh CANCON F4Fh CANCON_RO1(2) F2Fh CANCON_RO3(2) F0Fh RXF3EIDL

F6Eh CANSTAT F4Eh CANSTAT_RO1(2) F2Eh CANSTAT_RO3(2) F0Eh RXF3EIDH

F6Dh RXB0D7 F4Dh TXB0D7 F2Dh TXB2D7 F0Dh RXF3SIDL

F6Ch RXB0D6 F4Ch TXB0D6 F2Ch TXB2D6 F0Ch RXF3SIDH

F6Bh RXB0D5 F4Bh TXB0D5 F2Bh TXB2D5 F0Bh RXF2EIDL

F6Ah RXB0D4 F4Ah TXB0D4 F2Ah TXB2D4 F0Ah RXF2EIDH

F69h RXB0D3 F49h TXB0D3 F29h TXB2D3 F09h RXF2SIDL

F68h RXB0D2 F48h TXB0D2 F28h TXB2D2 F08h RXF2SIDH

F67h RXB0D1 F47h TXB0D1 F27h TXB2D1 F07h RXF1EIDL

F66h RXB0D0 F46h TXB0D0 F26h TXB2D0 F06h RXF1EIDH

F65h RXB0DLC F45h TXB0DLC F25h TXB2DLC F05h RXF1SIDL

F64h RXB0EIDL F44h TXB0EIDL F24h TXB2EIDL F04h RXF1SIDH

F63h RXB0EIDH F43h TXB0EIDH F23h TXB2EIDH F03h RXF0EIDL

F62h RXB0SIDL F42h TXB0SIDL F22h TXB2SIDL F02h RXF0EIDH

F61h RXB0SIDH F41h TXB0SIDH F21h TXB2SIDH F01h RXF0SIDL

F60h RXB0CON F40h TXB0CON F20h TXB2CON F00h RXF0SIDH

Note 1: Shaded registers are available in Access Bank low area, while the rest are available in Bank 15.

2: CANSTAT register is repeated in these locations to simplify application firmware. Unique names are given

for each instance of the controller register due to the Microchip header file requirement.

3: These registers are not CAN registers.

4: Unimplemented registers are read as ‘0’.

PIC18F2585/2680/4585/4680

EFFh —(4) EDFh —(4) EBFh —(4) E9Fh —(4)

EFEh —(4) EDEh —(4) EBEh —(4) E9Eh —(4)

EFDh —(4) EDDh —(4) EBDh —(4) E9Dh —(4)

EFCh —(4) EDCh —(4) EBCh —(4) E9Ch —(4)

EFBh —(4) EDBh —(4) EBBh —(4) E9Bh —(4)

EFAh —(4) EDAh —(4) EBAh —(4) E9Ah —(4)

EF9h —(4) ED9h —(4) EB9h —(4) E99h —(4)

EF8h —(4) ED8h —(4) EB8h —(4) E98h —(4)

EF7h —(4) ED7h —(4) EB7h —(4) E97h —(4)

EF6h —(4) ED6h —(4) EB6h —(4) E96h —(4)

EF5h —(4) ED5h —(4) EB5h —(4) E95h —(4)

EF4h —(4) ED4h —(4) EB4h —(4) E94h —(4)

EF3h —(4) ED3h —(4) EB3h —(4) E93h —(4)

EF2h —(4) ED2h —(4) EB2h —(4) E92h —(4)

EF1h —(4) ED1h —(4) EB1h —(4) E91h —(4)

EF0h —(4) ED0h —(4) EB0h —(4) E90h —(4)

EEFh —(4) ECFh —(4) EAFh —(4) E8Fh —(4)

EEEh —(4) ECEh —(4) EAEh —(4) E8Eh —(4)

EEDh —(4) ECDh —(4) EADh —(4) E8Dh —(4)

EECh —(4) ECCh —(4) EACh —(4) E8Ch —(4)

EEBh —(4) ECBh —(4) EABh —(4) E8Bh —(4)

EEAh —(4) ECAh —(4) EAAh —(4) E8Ah —(4)

EE9h —(4) EC9h —(4) EA9h —(4) E89h —(4)

EE8h —(4) EC8h —(4) EA8h —(4) E88h —(4)

EE7h —(4) EC7h —(4) EA7h —(4) E87h —(4)

EE6h —(4) EC6h —(4) EA6h —(4) E86h —(4)

EE5h —(4) EC5h —(4) EA5h —(4) E85h —(4)

EE4h —(4) EC4h —(4) EA4h —(4) E84h —(4)

EE3h —(4) EC3h —(4) EA3h —(4) E83h —(4)

EE2h —(4) EC2h —(4) EA2h —(4) E82h —(4)

EE1h —(4) EC1h —(4) EA1h —(4) E81h —(4)

EE0h —(4) EC0h —(4) EA0h —(4) E80h —(4)

TABLE 23-1: CAN CONTROLLER REGISTER MAP (CONTINUED)

Address(1) Name Address Name Address Name Address Name

Note 1: Shaded registers are available in Access Bank low area, while the rest are available in Bank 15.

2: CANSTAT register is repeated in these locations to simplify application firmware. Unique names are given

for each instance of the controller register due to the Microchip header file requirement.

3: These registers are not CAN registers.

4: Unimplemented registers are read as ‘0’.

PIC18F2585/2680/4585/4680

E7Fh CANCON_RO4(2) E5Fh CANCON_RO6(2) E3Fh CANCON_RO8(2) E1Fh —(4)

E7Eh CANSTAT_RO4(2) E5Eh CANSTAT_RO6(2) E3Eh CANSTAT_RO8(2) E1Eh —(4)

E7Dh B5D7 E5Dh B3D7 E3Dh B1D7 E1Dh —(4)

E7Ch B5D6 E5Ch B3D6 E3Ch B1D6 E1Ch —(4)

E7Bh B5D5 E5Bh B3D5 E3Bh B1D5 E1Bh —(4)

E7Ah B5D4 E5Ah B3D4 E3Ah B1D4 E1Ah —(4)

E79h B5D3 E59h B3D3 E39h B1D3 E19h —(4)

E78h B5D2 E58h B3D2 E38h B1D2 E18h —(4)

E77h B5D1 E57h B3D1 E37h B1D1 E17h —(4)

E76h B5D0 E56h B3D0 E36h B1D0 E16h —(4)

E75h B5DLC E55h B3DLC E35h B1DLC E15h —(4)

E74h B5EIDL E54h B3EIDL E34h B1EIDL E14h —(4)

E73h B5EIDH E53h B3EIDH E33h B1EIDH E13h —(4)

E72h B5SIDL E52h B3SIDL E32h B1SIDL E12h —(4)

E71h B5SIDH E51h B3SIDH E31h B1SIDH E11h —(4)

E70h B5CON E50h B3CON E30h B1CON E10h —(4)

E6Fh CANCON_RO5 E4Fh CANCON_RO7 E2Fh CANCON_RO9 E0Fh —(4)

E6Eh CANSTAT_RO5 E4Eh CANSTAT_RO7 E2Eh CANSTAT_RO9 E0Eh —(4)

E6Dh B4D7 E4Dh B2D7 E2Dh B0D7 E0Dh —(4)

E6Ch B4D6 E4Ch B2D6 E2Ch B0D6 E0Ch —(4)

E6Bh B4D5 E4Bh B2D5 E2Bh B0D5 E0Bh —(4)

E6Ah B4D4 E4Ah B2D4 E2Ah B0D4 E0Ah —(4)

E69h B4D3 E49h B2D3 E29h B0D3 E09h —(4)

E68h B4D2 E48h B2D2 E28h B0D2 E08h —(4)

E67h B4D1 E47h B2D1 E27h B0D1 E07h —(4)

E66h B4D0 E46h B2D0 E26h B0D0 E06h —(4)

E65h B4DLC E45h B2DLC E25h B0DLC E05h —(4)

E64h B4EIDL E44h B2EIDL E24h B0EIDL E04h —(4)

E63h B4EIDH E43h B2EIDH E23h B0EIDH E03h —(4)

E62h B4SIDL E42h B2SIDL E22h B0SIDL E02h —(4)

E61h B4SIDH E41h B2SIDH E21h B0SIDH E01h —(4)

E60h B4CON E40h B2CON E20h B0CON E00h —(4)

TABLE 23-1: CAN CONTROLLER REGISTER MAP (CONTINUED)

Address(1) Name Address Name Address Name Address Name

Note 1: Shaded registers are available in Access Bank low area, while the rest are available in Bank 15.

2: CANSTAT register is repeated in these locations to simplify application firmware. Unique names are given

for each instance of the controller register due to the Microchip header file requirement.

3: These registers are not CAN registers.

4: Unimplemented registers are read as ‘0’.

PIC18F2585/2680/4585/4680

DFFh —(4) DDFh —(4) DBFh —(4) D9Fh —(4)

DFEh —(4) DDEh —(4) DBEh —(4) D9Eh —(4)

DFDh —(4) DDDh —(4) DBDh —(4) D9Dh —(4)

DFCh TXBIE DDCh —(4) DBCh —(4) D9Ch —(4)

DFBh —(4) DDBh —(4) DBBh —(4) D9Bh —(4)

DFAh BIE0 DDAh —(4) DBAh —(4) D9Ah —(4)

DF9h —(4) DD9h —(4) DB9h —(4) D99h —(4)

DF8h BSEL0 DD8h SDFLC DB8h —(4) D98h —(4)

DF7h —(4) DD7h —(4) DB7h —(4) D97h —(4)

DF6h —(4) DD6h —(4) DB6h —(4) D96h —(4)

DF5h —(4) DD5h RXFCON1 DB5h —(4) D95h —(4)

DF4h —(4) DD4h RXFCON0 DB4h —(4) D94h —(4)

DF3h MSEL3 DD3h —(4) DB3h —(4) D93h RXF15EIDL

DF2h MSEL2 DD2h —(4) DB2h —(4) D92h RXF15EIDH

DF1h MSEL1 DD1h —(4) DB1h —(4) D91h RXF15SIDL

DF0h MSEL0 DD0h —(4) DB0h —(4) D90h RXF15SIDH

DEFh —(4) DCFh —(4) DAFh —(4) D8Fh —(4)

DEEh —(4) DCEh —(4) DAEh —(4) D8Eh —(4)

DEDh —(4) DCDh —(4) DADh —(4) D8Dh —(4)

DECh —(4) DCCh —(4) DACh —(4) D8Ch —(4)

DEBh —(4) DCBh —(4) DABh —(4) D8Bh RXF14EIDL

DEAh —(4) DCAh —(4) DAAh —(4) D8Ah RXF14EIDH

DE9h —(4) DC9h —(4) DA9h —(4) D89h RXF14SIDL

DE8h —(4) DC8h —(4) DA8h —(4) D88h RXF14SIDH

DE7h RXFBCON7 DC7h —(4) DA7h —(4) D87h RXF13EIDL

DE6h RXFBCON6 DC6h —(4) DA6h —(4) D86h RXF13EIDH

DE5h RXFBCON5 DC5h —(4) DA5h —(4) D85h RXF13SIDL

DE4h RXFBCON4 DC4h —(4) DA4h —(4) D84h RXF13SIDH

DE3h RXFBCON3 DC3h —(4) DA3h —(4) D83h RXF12EIDL

DE2h RXFBCON2 DC2h —(4) DA2h —(4) D82h RXF12EIDH

DE1h RXFBCON1 DC1h —(4) DA1h —(4) D81h RXF12SIDL

DE0h RXFBCON0 DC0h —(4) DA0h —(4) D80h RXF12SIDH

TABLE 23-1: CAN CONTROLLER REGISTER MAP (CONTINUED)

Address(1) Name Address Name Address Name Address Name

Note 1: Shaded registers are available in Access Bank low area, while the rest are available in Bank 15.

2: CANSTAT register is repeated in these locations to simplify application firmware. Unique names are given

for each instance of the controller register due to the Microchip header file requirement.

3: These registers are not CAN registers.

4: Unimplemented registers are read as ‘0’.

PIC18F2585/2680/4585/4680

TABLE 23-1: CAN CONTROLLER REGISTER MAP (CONTINUED)

Address(1) Name

D7Fh —(4)

D7Eh —(4)

D7Dh —(4)

D7Ch —(4)

D7Bh RXF11EIDL

D7Ah RXF11EIDH

D79h RXF11SIDL

D78h RXF11SIDH

D77h RXF10EIDL

D76h RXF10EIDH

D75h RXF10SIDL

D74h RXF10SIDH

D73h RXF9EIDL

D72h RXF9EIDH

D71h RXF9SIDL

D70h RXF9SIDH

D6Fh —(4)

D6Eh —(4)

D6Dh —(4)

D6Ch —(4)

D6Bh RXF8EIDL

D6Ah RXF8EIDH

D69h RXF8SIDL

D68h RXF8SIDH

D67h RXF7EIDL

D66h RXF7EIDH

D65h RXF7SIDL

D64h RXF7SIDH

D63h RXF6EIDL

D62h RXF6EIDH

D61h RXF6SIDL

D60h RXF6SIDH

Note 1: Shaded registers are available in Access Bank low area while the rest are available in Bank 15.

2: CANSTAT register is repeated in these locations to simplify application firmware. Unique names are given

for each instance of the controller register due to the Microchip header file requirement.

3: These registers are not CAN registers.

4: Unimplemented registers are read as ‘0’.

PIC18F2585/2680/4585/4680

23.3 CAN Modes of Operation

The PIC18F2585/2680/4585/4680 has six main modes

of operation:

• Configuration mode

• Disable mode

• Normal Operation mode

• Listen Only mode

• Loopback mode

• Error Recognition mode

All modes, except Error Recognition, are requested by

setting the REQOP bits (CANCON<7:5>). Error Recog-

nition mode is requested through the RXM bits of the

Receive Buffer register(s). Entry into a mode is

Acknowledged by monitoring the OPMODE bits.

When changing modes, the mode will not actually

change until all pending message transmissions are

complete. Because of this, the user must verify that the

device has actually changed into the requested mode

before further operations are executed.

23.3.1 CONFIGURATION MODE

The CAN module has to be initialized before the

activation. This is only possible if the module is in the

Configuration mode. The Configuration mode is

requested by setting the REQOP2 bit. Only when the

status bit, OPMODE2, has a high level can the initial-

ization be performed. Afterwards, the configuration

registers, the acceptance mask registers and the

acceptance filter registers can be written. The module

is activated by setting the REQOP control bits to zero.

The module will protect the user from accidentally

violating the CAN protocol through programming

errors. All registers which control the configuration of

the module can not be modified while the module is on-

line. The CAN module will not be allowed to enter the

Configuration mode while a transmission or reception

is taking place. The Configuration mode serves as a

lock to protect the following registers:

• Configuration Registers

• Functional Mode Selection Registers

• Bit Timing Registers

• Identifier Acceptance Filter Registers

• Identifier Acceptance Mask Registers

• Filter and Mask Control Registers

• Mask Selection Registers

In the Configuration mode, the module will not transmit

or receive. The error counters are cleared and the

interrupt flags remain unchanged. The programmer will

have access to Configuration registers that are access

restricted in other modes.

23.3.2 DISABLE MODE

In Disable mode, the module will not transmit or

receive. The module has the ability to set the WAKIF bit

due to bus activity; however, any pending interrupts will

remain and the error counters will retain their value.

If the REQOP<2:0> bits are set to ‘001’, the module will

enter the module Disable mode. This mode is similar to

disabling other peripheral modules by turning off the

module enables. This causes the module internal clock

to stop unless the module is active (i.e., receiving or

transmitting a message). If the module is active, the

module will wait for 11 recessive bits on the CAN bus,

detect that condition as an Idle bus, then accept the

module disable command. OPMODE<2:0> = 001

indicates whether the module successfully went into the

module Disable mode.

The WAKIF interrupt is the only module interrupt that is

still active in the Disable mode. If the WAKDIS is

cleared and WAKIE is set, the processor will receive an

interrupt whenever the module detects recessive to

dominant transition. On wake-up, the module will auto-

matically be set to the previous mode of operation. For

example, if the module was switched from Normal to

Disable mode on bus activity wake-up, the module will

automatically enter into Normal mode and the first mes-

sage that caused the module to wake-up is lost. The

module will not generate any error frame. Firmware

logic must detect this condition and make sure that

retransmission is requested. If the processor receives

a wake-up interrupt while it is sleeping, more than one

message may get lost. The actual number of messages

lost would depend on the processor oscillator start-up

time and incoming message bit rate.

The I/O pins will revert to normal I/O function when the

module is in the Disable mode.

23.3.3 NORMAL MODE

This is the standard operating mode of the

PIC18F2585/2680/4585/4680 devices. In this mode,

the device actively monitors all bus messages and gen-

erates Acknowledge bits, error frames, etc. This is also

the only mode in which the PIC18F2585/2680/4585/

4680 devices will transmit messages over the CAN

bus.

PIC18F2585/2680/4585/4680

23.3.4 LISTEN ONLY MODE

Listen Only mode provides a means for the

PIC18F2585/2680/4585/4680 devices to receive all

messages, including messages with errors. This mode

can be used for bus monitor applications or for

detecting the baud rate in ‘hot plugging’ situations. For

Auto-Baud Detection, it is necessary that there are at

least two other nodes which are communicating with

each other. The baud rate can be detected empirically

by testing different values until valid messages are

received. The Listen Only mode is a silent mode,

meaning no messages will be transmitted while in this

state, including error flags or Acknowledge signals. The

filters and masks can be used to allow only particular

messages to be loaded into the receive registers or the

filter masks can be set to all zeros to allow a message

with any identifier to pass. The error counters are reset

and deactivated in this state. The Listen Only mode is

activated by setting the mode request bits in the

CANCON register.

23.3.5 LOOPBACK MODE

This mode will allow internal transmission of messages

from the transmit buffers to the receive buffers without

actually transmitting messages on the CAN bus. This

mode can be used in system development and testing.

In this mode, the ACK bit is ignored and the device will

allow incoming messages from itself, just as if they

were coming from another node. The Loopback mode

is a silent mode, meaning no messages will be

transmitted while in this state, including error flags or

Acknowledge signals. The TXCAN pin will revert to port

I/O while the device is in this mode. The filters and

masks can be used to allow only particular messages

to be loaded into the receive registers. The masks can

be set to all zeros to provide a mode that accepts all

messages. The Loopback mode is activated by setting

the mode request bits in the CANCON register.

23.3.6 ERROR RECOGNITION MODE

The module can be set to ignore all errors and receive

any message. In functional Mode 0, the Error Recogni-

tion mode is activated by setting the RXM<1:0> bits in

the RXBnCON registers to ‘11’. In this mode, the data

which is in the message assembly buffer until the error

time, is copied in the receive buffer and can be read via

the CPU interface.

23.4 ECAN Module Functional Modes

In addition to CAN modes of operation, the ECAN mod-

ule offers a total of 3 functional modes. Each of these

modes are identified as Mode 0, Mode 1 and Mode 2.

23.4.1 MODE 0 – LEGACY MODE

Mode 0 is designed to be fully compatible with CAN

modules used in PIC18CXX8 and PIC18FXX8 devices.

This is the default mode of operation on all Reset

conditions. As a result, module code written for the

PIC18XX8 CAN module may be used on the ECAN

module without any code changes.

The following is the list of resources available in Mode 0:

• Three transmit buffers: TXB0, TXB1 and TXB2

• Two receive buffers: RXB0 and RXB1

• Two acceptance masks, one for each receive

buffer: RXM0, RXM1

• Six acceptance filters, 2 for RXB0 and 4 for RXB1:

RXF0, RXF1, RXF2, RXF3, RXF4, RXF5

23.4.2 MODE 1 – ENHANCED

LEGACY MODE

Mode 1 is similar to Mode 0, with the exception that

more resources are available in Mode 1. There are 16

acceptance filters and two acceptance mask registers.

Acceptance Filter 15 can be used as either an accep-

tance filter or an acceptance mask register. In addition

to three transmit and two receive buffers, there are six

more message buffers. One or more of these additional

buffers can be programmed as transmit or receive buff-

ers. These additional buffers can also be programmed

to automatically handle RTR messages.

Fourteen of sixteen acceptance filter registers can be

dynamically associated to any receive buffer and

acceptance mask register. One can use this capability

to associate more than one filter to any one buffer.

When a receive buffer is programmed to use standard

identifier messages, part of the full acceptance filter

the data byte filter is programmable from 0 to 18 bits.

This functionality simplifies implementation of high-level

protocols, such as the DeviceNet protocol.

The following is the list of resources available in Mode 1:

• Three transmit buffers: TXB0, TXB1 and TXB2

• Two receive buffers: RXB0 and RXB1

• Six buffers programmable as TX or RX: B0-B5

• Automatic RTR handling on B0-B5

• Sixteen dynamically assigned acceptance filters:

RXF0-RXF15

• Two dedicated acceptance mask registers;

RXF15 programmable as third mask:

RXM0-RXM1, RXF15

• Programmable data filter on standard identifier

messages: SDFLC

PIC18F2585/2680/4585/4680

23.4.3 MODE 2 – ENHANCED FIFO MODE

In Mode 2, two or more receive buffers are used to form

the receive FIFO (first in, first out) buffer. There is no

one-to-one relationship between the receive buffer and

acceptance filter registers. Any filter that is enabled and

linked to any FIFO receive buffer can generate

acceptance and cause FIFO to be updated.

FIFO length is user programmable, from 2-8 buffers

deep. FIFO length is determined by the very first

programmable buffer that is configured as a transmit

buffer. For example, if Buffer 2 (B2) is programmed as

a transmit buffer, FIFO consists of RXB0, RXB1, B0

and B1 – creating a FIFO length of 4. If all program-

mable buffers are configured as receive buffers, FIFO

will have the maximum length of 8.

The following is the list of resources available in Mode 2:

• Three transmit buffers: TXB0, TXB1 and TXB2

• Two receive buffers: RXB0 and RXB1

• Six buffers programmable as TX or RX; receive

buffers form FIFO: B0-B5

• Automatic RTR handling on B0-B5

• Sixteen acceptance filters: RXF0-RXF15

• Two dedicated acceptance mask registers;

RXF15 programmable as third mask:

RXM0-RXM1, RXF15

• Programmable data filter on standard identifier

messages: SDFLC, useful for DeviceNet protocol

23.5 CAN Message Buffers

23.5.1 DEDICATED TRANSMIT BUFFERS

The PIC18F2585/2680/4585/4680 devices implement

three dedicated transmit buffers – TXB0, TXB1 and

TXB2. Each of these buffers occupies 14 bytes of

SRAM and are mapped into the SFR memory map.

These are the only transmit buffers available in

Mode 0. Mode 1 and 2 may access these and other

additional buffers.

Each transmit buffer contains one control register

(TXBnCON), four identifier registers (TXBnSIDL,

TXBnSIDH, TXBnEIDL, TXBnEIDH), one data length

count register (TXBnDLC) and eight data byte registers

(TXBnDm).

23.5.2 DEDICATED RECEIVE BUFFERS

The PIC18F2585/2680/4585/4680 devices implement

two dedicated receive buffers – RXB0 and RXB1. Each

of these buffers occupies 14 bytes of SRAM and are

mapped into SFR memory map. These are the only

receive buffers available in Mode 0. Mode 1 and 2 may

access these and other additional buffers.

Each receive buffer contains one control register

(RXBnCON), four identifier registers (RXBnSIDL,

RXBnSIDH, RXBnEIDL, RXBnEIDH), one data length

count register (RXBnDLC) and eight data byte registers

(RXBnDm).

There is also a separate Message Assembly Buffer

(MAB) which acts as an additional receive buffer. MAB

is always committed to receiving the next message

from the bus and is not directly accessible to user firm-

ware. The MAB assembles all incoming messages one

by one. A message is transferred to appropriate

receive buffers only if the corresponding acceptance

filter criteria is met.

23.5.3 PROGRAMMABLE TRANSMIT/

RECEIVE BUFFERS

The ECAN module implements six new buffers: B0-B5.

These buffers are individually programmable as either

transmit or receive buffers. These buffers are available

only in Mode 1 and 2. As with dedicated transmit and

receive buffers, each of these programmable buffers

occupies 14 bytes of SRAM and are mapped into SFR

memory map.

Each buffer contains one control register (BnCON),

four identifier registers (BnSIDL, BnSIDH, BnEIDL,

BnEIDH), one data length count register (BnDLC) and

eight data byte registers (BnDm). Each of these regis-

ters contains two sets of control bits. Depending on

whether the buffer is configured as transmit or receive,

one would use the corresponding control bit set. By

default, all buffers are configured as receive buffers.

Each buffer can be individually configured as a transmit

or receive buffer by setting the corresponding TXENn

bit in the BSEL0 register.

When configured as transmit buffers, user firmware

may access transmit buffers in any order similar to

accessing dedicated transmit buffers. In receive config-

uration with Mode 1 enabled, user firmware may also

access receive buffers in any order required. But in

Mode 2, all receive buffers are combined to form a sin-

gle FIFO. Actual FIFO length is programmable by user

firmware. Access to FIFO must be done through the

FIFO Pointer bits (FP<4:0>) in the CANCON register. It

must be noted that there is no hardware protection

against out of order FIFO reads.

PIC18F2585/2680/4585/4680

23.5.4 PROGRAMMABLE AUTO-RTR

BUFFERS

In Mode 1 and 2, any of six programmable transmit/

receive buffers may be programmed to automatically

respond to predefined RTR messages without user

firmware intervention. Automatic RTR handling is

enabled by setting the TXnEN bit in the BSEL0 register

and the RTREN bit in the BnCON register. After this

setup, when an RTR request is received, the TXREQ

bit is automatically set and the current buffer content is

automatically queued for transmission as a RTR

response. As with all transmit buffers, once the TXREQ

bit is set, buffer registers become read-only and any

writes to them will be ignored.

The following outlines the steps required to

automatically handle RTR messages:

1. Set buffer to Transmit mode by setting TXnEN

bit to ‘1’ in BSEL0 register.

2. At least one acceptance filter must be

associated with this buffer and preloaded with

expected RTR identifier.

3. Bit RTREN in BnCON register must be set to ‘1’.

4. Buffer must be preloaded with the data to be

sent as a RTR response.

Normally, user firmware will keep buffer data registers

up to date. If firmware attempts to update the buffer

while an automatic RTR response is in the process of

transmission, all writes to buffers are ignored.

23.6 CAN Message Transmission

23.6.1 INITIATING TRANSMISSION

For the MCU to have write access to the message

buffer, the TXREQ bit must be clear, indicating that the

message buffer is clear of any pending message to be

transmitted. At a minimum, the SIDH, SIDL and DLC

registers must be loaded. If data bytes are present in

the message, the data registers must also be loaded. If

the message is to use extended identifiers, the

EIDH:EIDL registers must also be loaded and the

EXIDE bit set.

To initiate message transmission, the TXREQ bit must

be set for each buffer to be transmitted. When TXREQ

is set, the TXABT, TXLARB and TXERR bits will be

cleared. To successfully complete the transmission,

there must be at least one node with matching baud

rate on the network.

Setting the TXREQ bit does not initiate a message

transmission; it merely flags a message buffer as ready

for transmission. Transmission will start when the

device detects that the bus is available. The device will

then begin transmission of the highest priority message

that is ready.

When the transmission has completed successfully, the

TXREQ bit will be cleared, the TXBnIF bit will be set and

an interrupt will be generated if the TXBnIE bit is set.

If the message transmission fails, the TXREQ will remain

set, indicating that the message is still pending for trans-

mission and one of the following condition flags will be

set. If the message started to transmit but encountered

an error condition, the TXERR and the IRXIF bits will be

set and an interrupt will be generated. If the message lost

arbitration, the TXLARB bit will be set.

23.6.2 ABORTING TRANSMISSION

The MCU can request to abort a message by clearing

the TXREQ bit associated with the corresponding

message buffer (TXBnCON<3> or BnCON<3>). Set-

ting the ABAT bit (CANCON<4>) will request an abort

of all pending messages. If the message has not yet

started transmission, or if the message started but is

interrupted by loss of arbitration or an error, the abort

will be processed. The abort is indicated when the

module sets the TXABT bit for the corresponding buffer

(TXBnCON<6> or BnCON<6>). If the message has

started to transmit, it will attempt to transmit the current

message fully. If the current message is transmitted

fully and is not lost to arbitration or an error, the TXABT

bit will not be set because the message was transmit-

ted successfully. Likewise, if a message is being trans-

mitted during an abort request and the message is lost

to arbitration or an error, the message will not be

retransmitted and the TXABT bit will be set, indicating

that the message was successfully aborted.

Once an abort is requested by setting the ABAT or

TXABT bits, it cannot be cleared to cancel the abort

request. Only CAN module hardware or a POR

condition can clear it.

PIC18F2585/2680/4585/4680

23.6.3 TRANSMIT PRIORITY

Transmit priority is a prioritization within the

PIC18F2585/2680/4585/4680 devices of the pending

transmittable messages. This is independent from and

not related to any prioritization implicit in the message

arbitration scheme built into the CAN protocol. Prior to

sending the SOF, the priority of all buffers that are

queued for transmission is compared. The transmit

buffer with the highest priority will be sent first. If two

buffers have the same priority setting, the buffer with

the highest buffer number will be sent first. There are

four levels of transmit priority. If TXP bits for a particular

message buffer are set to ‘11’, that buffer has the high-

est possible priority. If TXP bits for a particular message

buffer are set to ‘00’, that buffer has the lowest possible

priority.

FIGURE 23-2: TRANSMIT BUFFERS

TXREQ

TXB0

TXABT

TXLARB

TXERR

TXB0IF

MESSAGE

Message

Queue

Control Transmit Byte Sequencer

TXREQ

TXB1

TXABT

TXLARB

TXERR

TXB1IF

MESSAGE

TXREQ

TXB2

TXABT

TXLARB

TXERR

TXB2IF

MESSAGE

TXB2IF

TXREQ

TXABT

TXLARB

TXERR

TXB3 - TXB8

PIC18F2585/2680/4585/4680

23.7 Message Reception

23.7.1 RECEIVING A MESSAGE

Of all receive buffers, the MAB is always committed to

receiving the next message from the bus. The MCU

can access one buffer while the other buffer is available

for message reception or holding a previously received

message.

When a message is moved into either of the receive

buffers, the associated RXFUL bit is set. This bit must

be cleared by the MCU when it has completed process-

ing the message in the buffer in order to allow a new

message to be received into the buffer. This bit

provides a positive lockout to ensure that the firmware

has finished with the message before the module

attempts to load a new message into the receive buffer.

If the receive interrupt is enabled, an interrupt will be

generated to indicate that a valid message has been

received.

Once a message is loaded into any matching buffer,

user firmware may determine exactly what filter caused

this reception by checking the filter hit bits in the

RXBnCON or BnCON registers. In Mode 0,

FILHIT<3:0> of RXBnCON serve as filter hit bits. In

Mode 1 and 2, FILHIT<4:0> of BnCON serves as filter

hit bits. The same registers also indicate whether the

current message is an RTR frame or not. A received

message is considered a standard identifier message if

the EXID bit in the RXBnSIDL or the BnSIDL register is

cleared. Conversely, a set EXID bit indicates an

extended identifier message. If the received message

is a standard identifier message, user firmware needs

to read the SIDL and SIDH registers. In the case of an

extended identifier message, firmware should read the

SIDL, SIDH, EIDL and EIDH registers. If the RXBnDLC

or BnDLC register contain non-zero data count, user

firmware should also read the corresponding number of

data bytes by accessing the RXBnDm or the BnDm

registers. When a received message is an RTR and if

the current buffer is not configured for automatic RTR

handling, user firmware must take appropriate action

and respond manually.

Each receive buffer contains RXM bits to set special

Receive modes. In Mode 0, RXM<1:0> bits in

RXBnCON define a total of four Receive modes. In

Mode 1 and 2, RXM1 bit, in combination with the EXID

mask and filter bit, define the same four Receive

modes. Normally, these bits are set to ‘00’ to enable

reception of all valid messages as determined by the

appropriate acceptance filters. In this case, the deter-

mination of whether or not to receive standard or

extended messages is determined by the EXIDE bit in

the acceptance filter register. In Mode 0, if the RXM bits

are set to ‘01’ or ‘10’, the receiver will accept only

messages with standard or extended identifiers,

respectively. If an acceptance filter has the EXIDE bit

set such that it does not correspond with the RXM

mode, that acceptance filter is rendered useless. In

Mode 1 and 2, setting EXID in the SIDL Mask register

will ensure that only standard or extended identifiers

are received. These two modes of RXM bits can be

used in systems where it is known that only standard or

extended messages will be on the bus. If the RXM bits

are set to ‘11’ (RXM1 = 1 in Mode 1 and 2), the buffer

will receive all messages regardless of the values of

the acceptance filters. Also, if a message has an error

before the end of frame, that portion of the message

assembled in the MAB before the error frame will be

loaded into the buffer. This mode may serve as a

valuable debugging tool for a given CAN network. It

should not be used in an actual system environment as

the actual system will always have some bus errors

and all nodes on the bus are expected to ignore them.

In Mode 1 and 2, when a programmable buffer is

configured as a transmit buffer and one or more

acceptance filters are associated with it, all incoming

messages matching this acceptance filter criteria will

be discarded. To avoid this scenario, user firmware

must make sure that there are no acceptance filters

associated with a buffer configured as a transmit buffer.

23.7.2 RECEIVE PRIORITY

When in Mode 0, RXB0 is the higher priority buffer and

has two message acceptance filters associated with it.

RXB1 is the lower priority buffer and has four acceptance

filters associated with it. The lower number of acceptance

filters makes the match on RXB0 more restrictive and

implies a higher priority for that buffer. Additionally, the

RXB0CON register can be configured such that if RXB0

contains a valid message and another valid message is

received, an overflow error will not occur and the new

message will be moved into RXB1 regardless of the

acceptance criteria of RXB1. There are also two

programmable acceptance filter masks available, one for

each receive buffer (see Section 23.5 “CAN Message

Buffers”).

In Mode 1 and 2, there are a total of 16 acceptance fil-

ters available and each can be dynamically assigned to

any of the receive buffers. A buffer with a lower number

has higher priority. Given this, if an incoming message

matches with two or more receive buffer acceptance

criteria, the buffer with the lower number will be loaded

with that message.

Note: The entire contents of the MAB are moved

into the receive buffer once a message is

accepted. This means that regardless of

the type of identifier (standard or

extended) and the number of data bytes

received, the entire receive buffer is over-

written with the MAB contents. Therefore,

the contents of all registers in the buffer

must be assumed to have been modified

when any message is received.

PIC18F2585/2680/4585/4680

23.7.3 ENHANCED FIFO MODE

When configured for Mode 2, two of the dedicated

receive buffers in combination with one or more

programmable transmit/receive buffers, are used to

create a maximum of an 8 buffer deep FIFO buffer. In

this mode, there is no direct correlation between filters

and receive buffer registers. Any filter that has been

enabled can generate an acceptance. When a

message has been accepted, it is stored in the next

available receive buffer register and an internal write

pointer is incremented. The FIFO can be a maximum of

8 buffers deep. The entire FIFO must consist of contig-

uous receive buffers. The FIFO head begins at RXB0

buffer and its tail spans toward B5. The maximum

length of the FIFO is limited by the presence or

absence of the first transmit buffer starting from B0. If a

buffer is configured as a transmit buffer, the FIFO

length is reduced accordingly. For instance, if B3 is

configured as a transmit buffer, the actual FIFO will

consist of RXB0, RXB1, B0, B1 and B2, a total of 5

buffers. If B0 is configured as a transmit buffer, the

FIFO length will be 2. If none of the programmable

buffers are configured as a transmit buffer, the FIFO will

be 8 buffers deep. A system that requires more transmit

buffers should try to locate transmit buffers at the very

end of B0-B5 buffers to maximize available FIFO

length.

When a message is received in FIFO mode, the inter-

rupt flag code bits (EICODE<4:0>) in the CANSTAT

FIFO has received a message. FIFO Pointer bits,

FP<3:0> in the CANCON register, point to the buffer

that contains data not yet read. The FIFO pointer bits,

in this sense, serve as the FIFO read pointer. The user

should use FP bits and read corresponding buffer data.

When receive data is no longer needed, the RXFUL bit

in the current buffer must be cleared, causing FP<3:0>

to be updated by the module.

To determine whether FIFO is empty or not, the user

may use FP<3:0> bits to access the RXFUL bit in the

current buffer. If RXFUL is cleared, the FIFO is consid-

ered to be empty. If it is set, the FIFO may contain one

or more messages. In Mode 2, the module also pro-

vides a bit called FIFO High Water Mark (FIFOWM) in

the ECANCON register. This bit can be used to cause

an interrupt whenever the FIFO contains only one or

four empty buffers. The FIFO high water mark interrupt

can serve as an early warning to a full FIFO condition.

23.7.4 TIME-STAMPING

The CAN module can be programmed to generate a

time-stamp for every message that is received. When

enabled, the module generates a capture signal for

CCP1, which in turn captures the value of either Timer1

or Timer3. This value can be used as the message

time-stamp.

To use the time-stamp capability, the CANCAP bit

(CIOCAN<4>) must be set. This replaces the capture

input for CCP1 with the signal generated from the CAN

module. In addition, CCP1CON<3:0> must be set to

‘0011’ to enable the CCP special event trigger for CAN

events.

23.8 Message Acceptance Filters

and Masks

The message acceptance filters and masks are used to

determine if a message in the Message Assembly

Buffer should be loaded into any of the receive buffers.

Once a valid message has been received into the MAB,

the identifier fields of the message are compared to the

filter values. If there is a match, that message will be

loaded into the appropriate receive buffer. The filter

masks are used to determine which bits in the identifier

are examined with the filters. A truth table is shown

below in Table 23-2 that indicates how each bit in the

identifier is compared to the masks and filters to deter-

mine if a message should be loaded into a receive

buffer. The mask essentially determines which bits to

apply the acceptance filters to. If any mask bit is set to

a zero, then that bit will automatically be accepted

regardless of the filter bit.

TABLE 23-2: FILTER/MASK TRUTH TABLE

In Mode 0, acceptance filters RXF0 and RXF1 and filter

mask RXM0 are associated with RXB0. Filters RXF2,

RXF3, RXF4 and RXF5 and mask RXM1 are

associated with RXB1.

Mask

bit n

Filter

bit n

Message

Identifier

bit n001

Accept or

Reject

bit n

0x xAccept

10 0Accept

10 1Reject

11 0Reject

11 1Accept

Legend: x = don’t care

PIC18F2585/2680/4585/4680

In Mode 1 and 2, there are an additional 10 acceptance

filters, RXF6-RXF15, creating a total of 16 available

filters. RXF15 can be used either as an acceptance

filter or acceptance mask register. Each of these

acceptance filters can be individually enabled or

disabled by setting or clearing the RXFENn bit in the

RXFCONn register. Any of these 16 acceptance filters

can be dynamically associated with any of the receive

buffers. Actual association is made by setting appropri-

ate bits in the RXFBCONn register. Each RXFBCONn

be used to associate a specific filter to any of available

receive buffers. User firmware may associate more

than one filter to any one specific receive buffer.

In addition to dynamic filter to buffer association, in

Mode 1 and 2, each filter can also be dynamically asso-

ciated to available acceptance mask registers. The

FILn_m bits in the MSELn register can be used to link

a specific acceptance filter to an acceptance mask reg-

ister. As with filter to buffer association, one can also

associate more than one mask to a specific acceptance

filter.

When a filter matches and a message is loaded into the

receive buffer, the filter number that enabled the mes-

sage reception is loaded into the FILHIT bit(s). In

Mode 0 for RXB1, the RXB1CON register contains the

FILHIT<2:0> bits. They are coded as follows:

•101 = Acceptance Filter 5 (RXF5)

•100 = Acceptance Filter 4 (RXF4)

•011 = Acceptance Filter 3 (RXF3)

•010 = Acceptance Filter 2 (RXF2)

•001 = Acceptance Filter 1 (RXF1)

•000 = Acceptance Filter 0 (RXF0)

The coding of the RXB0DBEN bit enables these three

bits to be used similarly to the FILHIT bits and to

distinguish a hit on filter RXF0 and RXF1, in either

RXB0 or after a rollover into RXB1.

•111 = Acceptance Filter 1 (RXF1)

•110 = Acceptance Filter 0 (RXF0)

•001 = Acceptance Filter 1 (RXF1)

•000 = Acceptance Filter 0 (RXF0)

If the RXB0DBEN bit is clear, there are six codes

corresponding to the six filters. If the RXB0DBEN bit is

set, there are six codes corresponding to the six filters,

plus two additional codes corresponding to RXF0 and

RXF1 filters, that rollover into RXB1.

In Mode 1 and 2, each buffer control register contains

5 bits of filter hit bits (FILHIT<4:0>). A binary value of ‘0’

indicates a hit from RXF0 and 15 indicates RXF15.

If more than one acceptance filter matches, the FILHIT

bits will encode the binary value of the lowest num-

bered filter that matched. In other words, if filter RXF2

and filter RXF4 match, FILHIT will be loaded with the

value for RXF2. This essentially prioritizes the

acceptance filters with a lower number filter having

higher priority. Messages are compared to filters in

ascending order of filter number.

The mask and filter registers can only be modified

when the PIC18F2585/2680/4585/4680 devices are in

Configuration mode.

FIGURE 23-3: MESSAGE ACCEPTANCE MASK AND FILTER OPERATION

Note: ‘000’ and ‘001’ can only occur if the

RXB0DBEN bit is set in the RXB0CON

rollover into RXB1.

Acceptance Filter Register Acceptance Mask Register

RxRqst

Message Assembly Buffer

RXFn0

RXFn1

RXFnn

RXMn0

RXMn1

RXMnn

Identifier

PIC18F2585/2680/4585/4680

23.9 Baud Rate Setting

All nodes on a given CAN bus must have the same

nominal bit rate. The CAN protocol uses Non-Return-

to-Zero (NRZ) coding which does not encode a clock

within the data stream. Therefore, the receive clock

must be recovered by the receiving nodes and

synchronized to the transmitter’s clock.

As oscillators and transmission time may vary from

node to node, the receiver must have some type of

Phase Lock Loop (PLL) synchronized to data transmis-

sion edges to synchronize and maintain the receiver

clock. Since the data is NRZ coded, it is necessary to

include bit stuffing to ensure that an edge occurs at

least every six bit times to maintain the Digital Phase

Lock Loop (DPLL) synchronization.

The bit timing of the PIC18F2585/2680/4585/4680 is

implemented using a DPLL that is configured to syn-

chronize to the incoming data and provides the nominal

timing for the transmitted data. The DPLL breaks each

bit time into multiple segments made up of minimal

periods of time called the

Time Quanta

(TQ).

Bus timing functions executed within the bit time frame,

such as synchronization to the local oscillator, network

transmission delay compensation and sample point

positioning, are defined by the programmable bit timing

logic of the DPLL.

All devices on the CAN bus must use the same bit rate.

However, all devices are not required to have the same

master oscillator clock frequency. For the different clock

frequencies of the individual devices, the bit rate has to

be adjusted by appropriately setting the baud rate

prescaler and number of Time Quanta in each segment.

The

Nominal Bit Rate

is the number of bits transmitted

per second, assuming an ideal transmitter with an ideal

oscillator, in the absence of resynchronization. The

nominal bit rate is defined to be a maximum of 1 Mb/s.

The

Nominal Bit Time

is defined as:

EQUATION 23-1:

The Nominal Bit Time can be thought of as being

divided into separate, non-overlapping time segments.

These segments (Figure 23-4) include:

• Synchronization Segment (Sync_Seg)

• Propagation Time Segment (Prop_Seg)

• Phase Buffer Segment 1 (Phase_Seg1)

• Phase Buffer Segment 2 (Phase_Seg2)

The time segments (and thus the Nominal Bit Time) are

in turn made up of integer units of time called Time

Quanta or TQ

(see Figure 23-4). By definition, the

Nominal Bit Time is programmable from a minimum of

8 TQ to a maximum of 25 TQ. Also by definition, the

minimum Nominal Bit Time is 1 μs, corresponding to a

maximum 1 Mb/s rate. The actual duration is given by

the following relationship.

EQUATION 23-2:

The Time Quantum is a fixed unit derived from the

oscillator period. It is also defined by the programmable

baud rate prescaler, with integer values from 1 to 64, in

addition to a fixed divide-by-two for clock generation.

Mathematically, this is:

EQUATION 23-3:

where FOSC is the clock frequency, TOSC is the

corresponding oscillator period and BRP is an integer

(0 through 63) represented by the binary values of

BRGCON1<5:0>. The equation above refers to the

effective clock frequency used by the microcontroller. If,

for example, a 10 MHz crystal in HS mode is used, then

the FOSC = 10 MHz and TOSC = 100 ns. If the same

10 MHz crystal is used in HS-PLL mode, then the

effective frequency is FOSC = 40 MHz and TOSC =25ns.

FIGURE 23-4: BIT TIME PARTITIONING

TBIT = 1/Nominal Bit Rate

Nominal Bit Time= TQ * (Sync_Seg + Prop_Seg +

Phase_Seg1 + Phase_Seg2)

TQ (μs) = (2 * (BRP + 1))/FOSC (MHz)

TQ (μs) = (2 * (BRP + 1)) * TOSC (μs)

Input

Sync Propagation

Segment

Phase

Segment 1

Phase

Segment 2

Sample Point

Nominal Bit Time

Bit

Time

Intervals

Signal

Segment

Sync

PIC18F2585/2680/4585/4680

23.9.1 EXTERNAL CLOCK, INTERNAL

CLOCK AND MEASURABLE JITTER

IN HS-PLL BASED OSCILLATORS

The microcontroller clock frequency generated from a

PLL circuit is subject to a jitter, also defined as Phase

Jitter or Phase Skew. For its PIC18 Enhanced micro-

controllers, Microchip specifies phase jitter (Pjitter) as

being 2% (Gaussian distribution, within 3 standard

deviations, see parameter F13 in Table 27-7) and Total

Jitter (Tjitter) as being 2 * Pjitter.

The CAN protocol uses a bit-stuffing technique that

inserts a bit of a given polarity following five bits with the

opposite polarity. This gives a total of 10 bits transmit-

ted without re-synchronization (compensation for jitter

or phase error).

Given the random nature of the jitter error added, it can

be shown that the total error caused by the jitter tends

to cancel itself over time. For a period of 10 bits, it is

necessary to add only two jitter intervals to correct for

jitter-induced error: one interval in the beginning of the

10-bit period and another at the end. The overall effect

is shown in Figure 23-5.

FIGURE 23-5: EFFECTS OF PHASE JITTER ON THE MICROCONTROLLER CLOCK

AND CAN BIT TIME

Once these considerations are taken into account, it is

possible to show that the relation between the jitter and

the total frequency error can be defined as:

where jitter is expressed in terms of time and NBT is the

Nominal Bit Time.

For example, assume a CAN bit rate of 125 Kb/s, which

gives an NBT of 8 μs. For a 16 MHz clock generated

from a 4x PLL, the jitter at this clock frequency is:

and resultant frequency error is:

Nominal Clock

Clock with Jitter

CAN bit Time

Phase Skew (Jitter)

CAN bit Jitter

with Jitter

ΔfTjitter

10 NBT×

------------------------2Pjitter

10 NBT×

------------------------

== 2% 1

16 MHz

-------------------

×0.02

16 6

×10

----------------- 1.25ns==

21.25 9–

×10()×

10 8 6–

×10()×

---------------------------------------3.125 5–

×10 0.0031%==

PIC18F2585/2680/4585/4680

Table 23-3 shows the relation between the clock

generated by the PLL and the frequency error from jitter

(measured jitter-induced error of 2%, Gaussian distribu-

tion, within 3 standard deviations), as a percentage of

the nominal clock frequency.

This is clearly smaller than the expected drift of a crystal

oscillator, typically specified at 100 ppm or 0.01%. If we

add jitter to oscillator drift, we have a total frequency drift

of 0.0132%. The total oscillator frequency errors for

common clock frequencies and bit rates, including both

drift and jitter, are shown in Table 23-4.

TABLE 23-3: FREQUENCY ERROR FROM JITTER AT VARIOUS PLL GENERATED CLOCK SPEEDS

TABLE 23-4: TOTAL FREQUENCY ERROR AT VARIOUS PLL GENERATED CLOCK SPEEDS

(100 PPM OSCILLATOR DRIFT, INCLUDING ERROR FROM JITTER)

PLL

Output

jitter

Frequency Error at Various Nominal Bit Times (Bit Rates)

8μs

(125 Kb/s)

4μs

(250 Kb/s)

2μs

(500 Kb/s)

1μs

(1 Mb/s)

40 MHz 0.5 ns 1 ns 0.00125% 0.00250% 0.005% 0.01%

24 MHz 0.83 ns 1.67 ns 0.00209% 0.00418% 0.008% 0.017%

16 MHz 1.25 ns 2.5 ns 0.00313% 0.00625% 0.013% 0.025%

Nominal PLL Output

Frequency Error at Various Nominal Bit Times (Bit Rates)

8μs

(125 Kb/s)

4μs

(250 Kb/s)

2μs

(500 Kb/s)

1μs

(1 Mb/s)

40 MHz 0.01125% 0.01250% 0.015% 0.02%

24 MHz 0.01209% 0.01418% 0.018% 0.027%

16 MHz 0.01313% 0.01625% 0.023% 0.035%

PIC18F2585/2680/4585/4680

23.9.2 TIME QUANTA

As already mentioned, the Time Quanta is a fixed unit

derived from the oscillator period and baud rate

prescaler. Its relationship to TBIT and the Nominal Bit

Rate is shown in Example 23-6.

EXAMPLE 23-6: CALCULATING TQ,

NOMINAL BIT RATE AND

NOMINAL BIT TIME

The frequencies of the oscillators in the different nodes

must be coordinated in order to provide a system wide

specified nominal bit time. This means that all oscilla-

tors must have a T

OSC that is an integral divisor of TQ.

It should also be noted that although the number of TQ

is programmable from 4 to 25, the usable minimum is

Q. There is no assurance that a bit time of less than

8 TQ in length will operate correctly.

23.9.3 SYNCHRONIZATION SEGMENT

This part of the bit time is used to synchronize the

various CAN nodes on the bus. The edge of the input

signal is expected to occur during the sync segment.

The duration is 1 TQ.

23.9.4 PROPAGATION SEGMENT

This part of the bit time is used to compensate for phys-

ical delay times within the network. These delay times

consist of the signal propagation time on the bus line

and the internal delay time of the nodes. The length of

the Propagation Segment can be programmed from

Q to 8 TQ by setting the PRSEG2:PRSEG0 bits.

23.9.5 PHASE BUFFER SEGMENTS

The phase buffer segments are used to optimally

locate the sampling point of the received bit within the

nominal bit time. The sampling point occurs between

Phase Segment 1 and Phase Segment 2. These

segments can be lengthened or shortened by the

resynchronization process. The end of Phase Segment

1 determines the sampling point within a bit time.

Phase Segment 1 is programmable from 1 TQ to 8 TQ

in duration. Phase Segment 2 provides delay before

the next transmitted data transition and is also

programmable from 1 TQ to 8 TQ in duration. However,

due to IPT requirements, the actual minimum length of

Phase Segment 2 is 2 TQ, or it may be defined to be

equal to the greater of Phase Segment 1 or the

Information Processing Time (IPT). The sampling point

should be as late as possible or approximately 80% of

the bit time.

23.9.6 SAMPLE POINT

The sample point is the point of time at which the bus

level is read and the value of the received bit is

determined. The sampling point occurs at the end of

Phase Segment 1. If the bit timing is slow and contains

many TQ, it is possible to specify multiple sampling of

the bus line at the sample point. The value of the

received bit is determined to be the value of the major-

ity decision of three values. The three samples are

taken at the sample point and twice before, with a time

of TQ/2 between each sample.

23.9.7 INFORMATION PROCESSING TIME

The Information Processing Time (IPT) is the time

segment starting at the sample point that is reserved

for calculation of the subsequent bit level. The CAN

specification defines this time to be less than or equal

to 2 TQ. The PIC18F2585/2680/4585/4680 devices

define this time to be 2 T

Q. Thus, Phase Segment 2

must be at least 2 TQ long.

TQ (μs) = (2 * (BRP + 1))/FOSC (MHz)

TBIT (μs) = TQ (μs) * number of TQ per bit interval

Nominal Bit Rate (bits/s) = 1/TBIT

This frequency (FOSC) refers to the effective

frequency used. If, for example, a 10 MHz external

signal is used along with a PLL, then the effective

frequency will be 4 x 10 MHz which equals 40 MHz.

CASE 1:

For FOSC = 16 MHz, BRP<5:0> = 00h and

Nominal Bit Time = 8 TQ:

TQ = (2 * 1)/16 = 0.1 25 μs (125 ns)

TBIT = 8 * 0.125 = 1 μs (10-6s)

Nominal Bit Rate = 1/10-6 = 106 bits/s (1 Mb/s)

CASE 2:

For FOSC = 20 MHz, BRP<5:0> = 01h and

Nominal Bit Time = 8 TQ:

TQ = (2 * 2)/20 = 0.2 μs (200 ns)

TBIT = 8 * 0.2 = 1.6 μs (1.6 * 10-6s)

Nominal Bit Rate = 1/1.6 * 10-6s = 625,000 bits/s

(625 Kb/s)

CASE 3:

For FOSC = 25 MHz, BRP<5:0> = 3Fh and

Nominal Bit Time = 25 TQ:

TQ = (2 * 64)/25 = 5.12 μs

TBIT = 25 * 5.12 = 128 μs (1.28 * 10 -4s)

Nominal Bit Rate = 1/1.28 * 10-4 = 7813 bits/s

(7.8 Kb/s)

PIC18F2585/2680/4585/4680

23.10 Synchronization

To compensate for phase shifts between the oscillator

frequencies of each of the nodes on the bus, each CAN

controller must be able to synchronize to the relevant

signal edge of the incoming signal. When an edge in

the transmitted data is detected, the logic will compare

the location of the edge to the expected time

(Sync_Seg). The circuit will then adjust the values of

Phase Segment 1 and Phase Segment 2 as necessary.

There are two mechanisms used for synchronization.

23.10.1 HARD SYNCHRONIZATION

Hard synchronization is only done when there is a

recessive to dominant edge during a bus Idle condition,

indicating the start of a message. After hard synchroni-

zation, the bit time counters are restarted with

Sync_Seg. Hard synchronization forces the edge

which has occurred to lie within the synchronization

segment of the restarted bit time. Due to the rules of

synchronization, if a hard synchronization occurs, there

will not be a resynchronization within that bit time.

23.10.2 RESYNCHRONIZATION

As a result of resynchronization, Phase Segment 1

may be lengthened or Phase Segment 2 may be short-

ened. The amount of lengthening or shortening of the

phase buffer segments has an upper bound given by

the Synchronization Jump Width (SJW). The value of

the SJW will be added to Phase Segment 1 (see

Figure 23-6) or subtracted from Phase Segment 2 (see

Figure 23-7). The SJW is programmable between 1 TQ

and 4 TQ.

Clocking information will only be derived from

recessive to dominant transitions. The property, that

only a fixed maximum number of successive bits have

the same value, ensures resynchronization to the bit

stream during a frame.

The phase error of an edge is given by the position of

the edge relative to Sync_Seg, measured in TQ. The

phase error is defined in magnitude of TQ as follows:

• e = 0 if the edge lies within Sync_Seg.

• e > 0 if the edge lies before the sample point.

• e < 0 if the edge lies after the sample point of the

previous bit.

If the magnitude of the phase error is less than, or equal

to, the programmed value of the Synchronization Jump

Width, the effect of a resynchronization is the same as

that of a hard synchronization.

If the magnitude of the phase error is larger than the

Synchronization Jump Width and if the phase error is

positive, then Phase Segment 1 is lengthened by an

amount equal to the Synchronization Jump Width.

If the magnitude of the phase error is larger than the

resynchronization jump width and if the phase error is

negative, then Phase Segment 2 is shortened by an

amount equal to the Synchronization Jump Width.

23.10.3 SYNCHRONIZATION RULES

• Only one synchronization within one bit time is

allowed.

• An edge will be used for synchronization only if

the value detected at the previous sample point

(previously read bus value) differs from the bus

value immediately after the edge.

• All other recessive to dominant edges fulfilling

rules 1 and 2 will be used for resynchronization,

with the exception that a node transmitting a

dominant bit will not perform a resynchronization

as a result of a recessive to dominant edge with a

positive phase error.

PIC18F2585/2680/4585/4680

FIGURE 23-6: LENGTHENING A BIT PERIOD (ADDING SJW TO PHASE SEGMENT 1)

FIGURE 23-7: SHORTENING A BIT PERIOD (SUBTRACTING SJW FROM PHASE SEGMENT 2)

23.11 Programming Time Segments

Some requirements for programming of the time

segments:

• Prop_Seg + Phase_Seg 1 ≥ Phase_Seg 2

• Phase_Seg 2 ≥ Sync Jump Width.

For example, assume that a 125 kHz CAN baud rate is

desired, using 20 MHz for FOSC. With a TOSC of 50 ns,

a baud rate prescaler value of 04h gives a TQ of 500 ns.

To obtain a Nominal Bit Rate of 125 kHz, the Nominal

Bit Time must be 8 μs or 16 TQ.

Using 1 TQ for the Sync_Seg, 2 TQ for the Prop_Seg

and 7 TQ for Phase Segment 1 would place the sample

point at 10 TQ after the transition. This leaves 6 TQ for

Phase Segment 2.

By the rules above, the Sync Jump Width could be the

maximum of 4 TQ. However, normally a large SJW is

only necessary when the clock generation of the differ-

ent nodes is inaccurate or unstable, such as using

ceramic resonators. Typically, an SJW of 1 is enough.

23.12 Oscillator Tolerance

As a rule of thumb, the bit timing requirements allow

ceramic resonators to be used in applications with

transmission rates of up to 125 Kbit/sec. For the full bus

speed range of the CAN protocol, a quartz oscillator is

required. A maximum node-to-node oscillator variation

of 1.7% is allowed.

Input

Sync Prop

Segment

Phase

Segment 1

Phase

Segment 2

≤ SJW

Sample Point

Signal

Nominal Bit Length

Actual Bit Length

Bit

Time

Segments

Sync

Prop

Segment

Phase

Segment 1

Phase

Segment 2 ≤ SJW

TQSample Point

Nominal Bit Length

Actual Bit Length

PIC18F2585/2680/4585/4680

23.13 Bit Timing Configuration

Registers

The Baud Rate Control registers (BRGCON1,

BRGCON2, BRGCON3) control the bit timing for the

CAN bus interface. These registers can only be

modified when the PIC18F2585/2680/4585/4680

devices are in Configuration mode.

23.13.1 BRGCON1

The BRP bits control the baud rate prescaler. The

SJW<1:0> bits select the synchronization jump width in

terms of multiples of TQ.

23.13.2 BRGCON2

The PRSEG bits set the length of the propagation seg-

ment in terms of TQ. The SEG1PH bits set the length of

Phase Segment 1 in TQ. The SAM bit controls how

many times the RXCAN pin is sampled. Setting this bit

to a ‘1’ causes the bus to be sampled three times: twice

at TQ/2 before the sample point and once at the normal

sample point (which is at the end of Phase Segment 1).

The value of the bus is determined to be the value read

during at least two of the samples. If the SAM bit is set

to a ‘0’, then the RXCAN pin is sampled only once at

the sample point. The SEG2PHTS bit controls how the

length of Phase Segment 2 is determined. If this bit is

set to a ‘1’, then the length of Phase Segment 2 is

determined by the SEG2PH bits of BRGCON3. If the

SEG2PHTS bit is set to a ‘0’, then the length of Phase

Segment 2 is the greater of Phase Segment 1 and the

Information Processing Time (which is fixed at 2 TQ for

the PIC18F2585/2680/4585/4680).

23.13.3 BRGCON3

The PHSEG2<2:0> bits set the length (in TQ) of Phase

Segment 2 if the SEG2PHTS bit is set to a ‘1’. If the

SEG2PHTS bit is set to a ‘0’, then the PHSEG2<2:0>

bits have no effect.

23.14 Error Detection

The CAN protocol provides sophisticated error

detection mechanisms. The following errors can be

detected.

23.14.1 CRC ERROR

With the Cyclic Redundancy Check (CRC), the trans-

mitter calculates special check bits for the bit

sequence, from the start of a frame until the end of the

data field. This CRC sequence is transmitted in the

CRC field. The receiving node also calculates the CRC

sequence using the same formula and performs a

comparison to the received sequence. If a mismatch is

detected, a CRC error has occurred and an error frame

is generated. The message is repeated.

23.14.2 ACKNOWLEDGE ERROR

In the Acknowledge field of a message, the transmitter

checks if the Acknowledge slot (which was sent out as

a recessive bit) contains a dominant bit. If not, no other

node has received the frame correctly. An Acknowl-

edge error has occurred, an error frame is generated

and the message will have to be repeated.

23.14.3 FORM ERROR

If a node detects a dominant bit in one of the four

segments, including End-Of-Frame, interframe space,

Acknowledge delimiter or CRC delimiter, then a form

error has occurred and an error frame is generated.

The message is repeated.

23.14.4 BIT ERROR

A bit error occurs if a transmitter sends a dominant bit

and detects a recessive bit, or if it sends a recessive bit

and detects a dominant bit, when monitoring the actual

bus level and comparing it to the just transmitted bit. In

the case where the transmitter sends a recessive bit

and a dominant bit is detected during the arbitration

field and the Acknowledge slot, no bit error is

generated because normal arbitration is occurring.

23.14.5 STUFF BIT ERROR

lf, between the Start-Of-Frame and the CRC delimiter,

six consecutive bits with the same polarity are

detected, the bit stuffing rule has been violated. A stuff

bit error occurs and an error frame is generated. The

message is repeated.

23.14.6 ERROR STATES

Detected errors are made public to all other nodes via

error frames. The transmission of the erroneous

message is aborted and the frame is repeated as soon

as possible. Furthermore, each CAN node is in one of

the three error states: “error-active”, “error-passive” or

“bus-off”, according to the value of the internal error

counters. The error-active state is the usual state

where the bus node can transmit messages and

activate error frames (made of dominant bits) without

any restrictions. In the error-passive state, messages

and passive error frames (made of recessive bits) may

be transmitted. The bus-off state makes it temporarily

impossible for the station to participate in the bus

communication. During this state, messages can

neither be received nor transmitted.

23.14.7 ERROR MODES AND ERROR

COUNTERS

The PIC18F2585/2680/4585/4680 devices contain two

error counters: the Receive Error Counter (RXERRCNT)

and the Transmit Error Counter (TXERRCNT). The

values of both counters can be read by the MCU. These

counters are incremented or decremented in

accordance with the CAN bus specification.

PIC18F2585/2680/4585/4680

The PIC18F2585/2680/4585/4680 devices are error-

active if both error counters are below the error-passive

limit of 128. They are error-passive if at least one of the

error counters equals or exceeds 128. They go to bus-

off if the transmit error counter equals or exceeds the

bus-off limit of 256. The devices remain in this state

until the bus-off recovery sequence is received. The

bus-off recovery sequence consists of 128 occurrences

of 11 consecutive recessive bits (see Figure 23-8).

Note that the CAN module, after going bus-off, will

recover back to error-active without any intervention by

the MCU if the bus remains Idle for 128 x 11 bit times.

If this is not desired, the error Interrupt Service Routine

should address this. The current Error mode of the

CAN module can be read by the MCU via the

COMSTAT register.

Additionally, there is an Error State Warning flag bit,

EWARN, which is set if at least one of the error

counters equals or exceeds the error warning limit of

96. EWARN is reset if both error counters are less than

the error warning limit.

FIGURE 23-8: ERROR MODES STATE DIAGRAM

23.15 CAN Interrupts

The module has several sources of interrupts. Each of

these interrupts can be individually enabled or

disabled. The PIR3 register contains interrupt flags.

The PIE3 register contains the enables for the 8 main

interrupts. A special set of read-only bits in the

CANSTAT register, the ICODE bits, can be used in

combination with a jump table for efficient handling of

interrupts.

All interrupts have one source, with the exception of the

error interrupt and buffer interrupts in Mode 1 and 2. Any

of the error interrupt sources can set the error interrupt

flag. The source of the error interrupt can be determined

by reading the Communication Status register,

COMSTAT. In Mode 1 and 2, there are two interrupt

enable/disable and flag bits – one for all transmit buffers

and the other for all receive buffers.

The interrupts can be broken up into two categories:

receive and transmit interrupts.

The receive related interrupts are:

• Receive Interrupts

• Wake-up Interrupt

• Receiver Overrun Interrupt

• Receiver Warning Interrupt

• Receiver Error-Passive Interrupt

The transmit related interrupts are:

• Transmit Interrupts

• Transmitter Warning Interrupt

• Transmitter Error-Passive Interrupt

• Bus-Off Interrupt

Bus-

Off

Error

Active

Error

Passive

RXERRCNT < 127 or

TXERRCNT < 127

RXERRCNT > 127 or

TXERRCNT > 127

TXERRCNT > 255

128 occurrences of

11 consecutive

“recessive” bits

Reset

PIC18F2585/2680/4585/4680

23.15.1 INTERRUPT CODE BITS

To simplify the interrupt handling process in user firm-

ware, the ECAN module encodes a special set of bits. In

Mode 0, these bits are ICODE<3:1> in the CANSTAT

the CANSTAT register. Interrupts are internally prioritized

such that the higher priority interrupts are assigned lower

values. Once the highest priority interrupt condition has

been cleared, the code for the next highest priority inter-

rupt that is pending (if any) will be reflected by the ICODE

bits (see Table 23-5). Note that only those interrupt

sources that have their associated interrupt enable bit set

will be reflected in the ICODE bits.

In Mode 2, when a receive message interrupt occurs,

the EICODE bits will always consist of ‘10000’. User

firmware may use FIFO pointer bits to actually access

the next available buffer.

23.15.2 TRANSMIT INTERRUPT

When the transmit interrupt is enabled, an interrupt will

be generated when the associated transmit buffer

becomes empty and is ready to be loaded with a new

message. In Mode 0, there are separate interrupt

enable/disable and flag bits for each of the three dedi-

cated transmit buffers. The TXBnIF bit will be set to indi-

cate the source of the interrupt. The interrupt is cleared

by the MCU, resetting the TXBnIF bit to a ‘0’. In Mode 1

and 2, all transmit buffers share one interrupt enable/

disable bit and one flag bit. In Mode 1 and 2, TXBnIE in

PIE3 and TXBnIF in PIR3 indicate when a transmit

buffer has completed transmission of its message. TXB-

nIF, TXBnIE and TXBnIP in PIR3, PIE3 and IPR3,

respectively, are not used in Mode 1 and 2. Individual

transmit buffer interrupts can be enabled or disabled by

setting or clearing TXBIE and BIE0 register bits. When a

shared interrupt occurs, user firmware must poll the

TXREQ bit of all transmit buffers to detect the source of

interrupt.

23.15.3 RECEIVE INTERRUPT

When the receive interrupt is enabled, an interrupt will

be generated when a message has been successfully

received and loaded into the associated receive buffer.

This interrupt is activated immediately after receiving

the End-Of-Frame (EOF) field.

In Mode 0, the RXBnIF bit is set to indicate the source

of the interrupt. The interrupt is cleared by the MCU,

resetting the RXBnIF bit to a ‘0’.

In Mode 1 and 2, all receive buffers share RXBIE,

RXBIF and RXBIP in PIE3, PIR3 and IPR3, respec-

tively. Bits RXBnIE, RXBnIF and RXBnIP are not used.

Individual receive buffer interrupts can be controlled by

the TXBIE and BIE0 registers. In Mode 1, when a

shared receive interrupt occurs, user firmware must

poll the RXFUL bit of each receive buffer to detect the

source of interrupt. In Mode 2, a receive interrupt

indicates that the new message is loaded into FIFO.

FIFO can be read by using FIFO Pointer bits, FP.

TABLE 23-5: VALUES FOR ICODE<3:1>

23.15.4 MESSAGE ERROR INTERRUPT

When an error occurs during transmission or reception

of a message, the message error flag, IRXIF, will be set

and if the IRXIE bit is set, an interrupt will be generated.

This is intended to be used to facilitate baud rate

determination when used in conjunction with Listen

Only mode.

ICODE

<2:0> Interrupt Boolean Expression

000 None ERR•WAK•TX0•TX1•TX2•RX0•RX1

001 Error ERR

010 TXB2 ERR•TX0•TX1•TX2

011 TXB1 ERR•TX0•TX1

100 TXB0 ERR•TX0

101 RXB1 ERR•TX0•TX1•TX2•RX0•RX1

110 RXB0 ERR•TX0•TX1•TX2•RX0

111 Wake on

Interrupt

ERR•TX0•TX1•TX2•RX0•RX1•WAK

Legend:

ERR = ERRIF * ERRIE RX0 = RXB0IF * RXB0IE

TX0 = TXB0IF * TXB0IE RX1 = RXB1IF * RXB1IE

TX1 = TXB1IF * TXB1IE WAK = WAKIF * WAKIE

TX2 = TXB2IF * TXB2IE

PIC18F2585/2680/4585/4680

23.15.5 BUS ACTIVITY WAKE-UP

INTERRUPT

When the PIC18F2585/2680/4585/4680 devices are in

Sleep mode and the bus activity wake-up interrupt is

enabled, an interrupt will be generated and the WAKIF

bit will be set when activity is detected on the CAN bus.

This interrupt causes the PIC18F2585/2680/4585/

4680 devices to exit Sleep mode. The interrupt is reset

by the MCU, clearing the WAKIF bit.

23.15.6 ERROR INTERRUPT

When the error interrupt is enabled, an interrupt is

generated if an overflow condition occurs or if the error

state of the transmitter or receiver has changed. The

error flags in COMSTAT will indicate one of the

following conditions.

23.15.6.1 Receiver Overflow

An overflow condition occurs when the MAB has

assembled a valid received message (the message

meets the criteria of the acceptance filters) and the

receive buffer associated with the filter is not available

for loading of a new message. The associated

RXBnOVFL bit in the COMSTAT register will be set to

indicate the overflow condition. This bit must be cleared

by the MCU.

23.15.6.2 Receiver Warning

The receive error counter has reached the MCU

warning limit of 96.

23.15.6.3 Transmitter Warning

The transmit error counter has reached the MCU

warning limit of 96.

23.15.6.4 Receiver Bus Passive

The receive error counter has exceeded the error-

passive limit of 127 and the device has gone to

error-passive state.

23.15.6.5 Transmitter Bus Passive

The transmit error counter has exceeded the error-

passive limit of 127 and the device has gone to

error-passive state.

23.15.6.6 Bus-Off

The transmit error counter has exceeded 255 and the

device has gone to bus-off state.

23.15.6.7 Interrupt Acknowledge

Interrupts are directly associated with one or more

status flags in the PIR register. Interrupts are pending

as long as one of the flags is set. Once an interrupt flag

is set by the device, the flag can not be reset by the

microcontroller until the interrupt condition is removed.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

24.0 SPECIAL FEATURES OF THE

CPU

PIC18F2585/2680/4585/4680 devices include several

features intended to maximize reliability and minimize

cost through elimination of external components.

These are:

• Oscillator Selection

• Resets:

- Power-on Reset (POR)

- Power-up Timer (PWRT)

- Oscillator Start-up Timer (OST)

- Brown-out Reset (BOR)

• Interrupts

• Watchdog Timer (WDT)

• Fail-Safe Clock Monitor

• Two-Speed Start-up

• Code Protection

• ID Locations

• In-Circuit Serial Programming

The oscillator can be configured for the application

depending on frequency, power, accuracy and cost. All

of the options are discussed in detail in Section 2.0

“Oscillator Configurations”.

A complete discussion of device Resets and interrupts

is available in previous sections of this data sheet.

In addition to their Power-up and Oscillator Start-up

Timers provided for Resets, PIC18F2585/2680/4585/

4680 devices have a Watchdog Timer, which is either

permanently enabled via the Configuration bits or

software controlled (if configured as disabled).

The inclusion of an internal RC oscillator also provides

the additional benefits of a Fail-Safe Clock Monitor

(FSCM) and Two-Speed Start-up. FSCM provides for

background monitoring of the peripheral clock and

automatic switchover in the event of its failure. Two-

Speed Start-up enables code to be executed almost

immediately on start-up, while the primary clock source

completes its start-up delays.

All of these features are enabled and configured by

setting the appropriate Configuration register bits.

24.1 Configuration Bits

The Configuration bits can be programmed (read as

‘0’) or left unprogrammed (read as ‘1’) to select various

device configurations. These bits are mapped starting

at program memory location 300000h.

The user will note that address 300000h is beyond the

user program memory space. In fact, it belongs to the

configuration memory space (300000h-3FFFFFh), which

can only be accessed using table reads and table writes.

Programming the Configuration registers is done in a

manner similar to programming the Flash memory. The

WR bit in the EECON1 register starts a self-timed write

to the Configuration register. In normal operation mode,

a TBLWT instruction with the TBLPTR pointing to the

Configuration register sets up the address and the data

for the Configuration register write. Setting the WR bit

starts a long

write to the Configuration register. The

Configuration registers are written a byte at a time. To

write or erase a configuration cell, a TBLWT instruction

can write a ‘1’ or a ‘0’ into the cell. For additional details

on Flash programming, refer to Section 6.5 “Writing

to Flash Program Memory”.

TABLE 24-1: CONFIGURATION BITS AND DEVICE IDs

File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Default/

Unprogrammed

Value

300001h CONFIG1H IESO FCMEN —— FOSC3 FOSC2 FOSC1 FOSC0 00-- 0111

300002h CONFIG2L ——— BORV1 BORV0 BOREN1 BOREN0 PWRTEN ---1 1111

300003h CONFIG2H ——— WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN ---1 1111

300005h CONFIG3H MCLRE — — — — LPT1OSC PBADEN —1--- -01-

300006h CONFIG4L DEBUG XINST BBSIZ1 BBSIZ2 —LVP—STVREN1000 -1-1

300008h CONFIG5L ——— — CP3 CP2 CP1 CP0 ---- 1111

300009h CONFIG5H CPD CPB — — — — — — 11-- ----

30000Ah CONFIG6L ——— — WRT3 WRT2 WRT1 WRT0 ---- 1111

30000Bh CONFIG6H WRTD WRTB WRTC —————111- ----

30000Ch CONFIG7L ——— — EBTR3 EBTR2 EBTR1 EBTR0 ---- 1111

30000Dh CONFIG7H —EBTRB— — — — — — -1-- ----

3FFFFEh DEVID1 DEV2 DEV1 DEV0 REV4 REV3 REV2 REV1 REV0 xxxx xxxx(1)

3FFFFFh DEVID2 DEV10 DEV9 DEV8 DEV7 DEV6 DEV5 DEV4 DEV3 0000 1100

Legend: x = unknown, u = unchanged, - = unimplemented, q = value depends on condition.

Shaded cells are unimplemented, read as ‘0’.

Note 1: See Register 24-14 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user.

PIC18F2585/2680/4585/4680

R/P-0 R/P-0 U-0 U-0 R/P-0 R/P-1 R/P-1 R/P-1

IESO FCMEN —— FOSC3 FOSC2 FOSC1 FOSC0

bit 7 bit 0

bit 7 IESO: Internal/External Oscillator Switchover bit

1 = Oscillator Switchover mode enabled

0 = Oscillator Switchover mode disabled

bit 6 FCMEN: Fail-Safe Clock Monitor Enable bit

1 = Fail-Safe Clock Monitor enabled

0 = Fail-Safe Clock Monitor disabled

bit 5-4 Unimplemented: Read as ‘0’

bit 3-0 FOSC3:FOSC0: Oscillator Selection bits

11xx = External RC oscillator, CLKO function on RA6

101x = External RC oscillator, CLKO function on RA6

1001 = Internal oscillator block, CLKO function on RA6, port function on RA7

1000 = Internal oscillator block, port function on RA6 and RA7

0111 = External RC oscillator, port function on RA6

0110 = HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1)

0101 = EC oscillator, port function on RA6

0100 = EC oscillator, CLKO function on RA6

0011 = External RC oscillator, CLKO function on RA6

0010 = HS oscillator

0001 = XT oscillator

0000 = LP oscillator

Legend:

R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1

— — — BORV1 BORV0 BOREN1(1) BOREN0(1) PWRTEN(1)

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-3 BORV1:BORV0: Brown-out Reset Voltage bits

11 = VBOR set to 2.1V

10 = VBOR set to 2.8V

01 = VBOR set to 4.3V

00 = VBOR set to 4.6V

bit 2-1 BOREN1:BOREN0 Brown-out Reset Enable bits(1)

11 = Brown-out Reset enabled in hardware only (SBOREN is disabled)

10 = Brown-out Reset enabled in hardware only and disabled in Sleep mode

(SBOREN is disabled)

01 = Brown-out Reset enabled and controlled by software (SBOREN is enabled)

00 = Brown-out Reset disabled in hardware and software

bit 0 PWRTEN: Power-up Timer Enable bit(1)

1 = PWRT disabled

0 = PWRT enabled

Note 1: The Power-up Timer is decoupled from Brown-out Reset, allowing these features to

be independently controlled.

Legend:

R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1

— — — WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN

bit 7 bit 0

bit 7-5 Unimplemented: Read as ‘0’

bit 4-1 WDTPS3:WDTPS0: Watchdog Timer Postscale Select bits

1111 = 1:32,768

1110 = 1:16,384

1101 = 1:8,192

1100 = 1:4,096

1011 = 1:2,048

1010 = 1:1,024

1001 = 1:512

1000 = 1:256

0111 = 1:128

0110 = 1:64

0101 = 1:32

0100 = 1:16

0011 = 1:8

0010 = 1:4

0001 = 1:2

0000 = 1:1

bit 0 WDTEN: Watchdog Timer Enable bit

1 = WDT enabled

0 = WDT disabled (control is placed on the SWDTEN bit)

Legend:

R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

R/P-1 U-0 U-0 U-0 U-0 R/P-0 R/P-1 U-0

MCLRE ———— LPT1OSC PBADEN —

bit 7 bit 0

bit 7 MCLRE: MCLR Pin Enable bit

1 = MCLR pin enabled; RE3 input pin disabled

0 = RE3 input pin enabled; MCLR disabled

bit 6-3 Unimplemented: Read as ‘0’

bit 2 LPT1OSC: Low-Power Timer 1 Oscillator Enable bit

1 = Timer1 configured for low-power operation

0 = Timer1 configured for higher power operation

bit 1 PBADEN: PORTB A/D Enable bit

(Affects ADCON1 Reset state. ADCON1 controls PORTB<4:0> pin configuration.)

1 = PORTB<4:0> pins are configured as analog input channels on Reset

0 = PORTB<4:0> pins are configured as digital I/O on Reset

bit 0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

R/P-1 R/P-0 R/P-0 R/P-0 U-0 R/P-1 U-0 R/P-1

DEBUG XINST BBSIZ1 BBSIZ2 —LVP—STVREN

bit 7 bit 0

bit 7 DEBUG: Background Debugger Enable bit

1 = Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins

0 = Background debugger enabled, RB6 and RB7 are dedicated to In-Circuit Debug

bit 6 XINST: Extended Instruction Set Enable bit

1 = Instruction set extension and Indexed Addressing mode enabled

0 = Instruction set extension and Indexed Addressing mode disabled (Legacy mode)

bit 5 BBSIZ1: Boot Block Size Select Bit 1

11 = 4K words (8 Kbytes) boot block

10 = 4K words (8 Kbytes) boot block

bit 4 BBSIZ2: Boot Block Size Select Bit 0

01 = 2K words (4 Kbytes) boot block

00 = 1K words (2 Kbytes) boot block

bit 3 Unimplemented: Read as ‘0’

bit 2 LVP: Single-Supply ICSP Enable bit

1 = Single-Supply ICSP enabled

0 = Single-Supply ICSP disabled

bit 1 Unimplemented: Read as ‘0’

bit 0 STVREN: Stack Full/Underflow Reset Enable bit

1 = Stack full/underflow will cause Reset

0 = Stack full/underflow will not cause Reset

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 U-0 R/C-1 R/C-1 R/C-1 R/C-1

— — — —CP3

(1) CP2 CP1 CP0

bit 7 bit 0

bit 7-4 Unimplemented: Read as ‘0’

bit 3 CP3: Code Protection bit(1)

1 = Block 3 (00C000-00FFFFh) not code-protected

0 = Block 3 (00C000-00FFFFh) code-protected

Note 1: Unimplemented in PIC18FX585 devices; maintain this bit set.

bit 2 CP2: Code Protection bit

1 = Block 2 (008000-00BFFFh) not code-protected

0 = Block 2 (008000-00BFFFh) code-protected

bit 1 CP1: Code Protection bit

1 = Block 1 (004000-007FFFh) not code-protected

0 = Block 1 (004000-007FFFh) code-protected

bit 0 CP0: Code Protection bit

1 = Block 0 (000800-003FFFh) not code-protected

0 = Block 0 (000800-003FFFh) code-protected

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

R/C-1 R/C-1 U-0 U-0 U-0 U-0 U-0 U-0

CPD CPB — — — — — —

bit 7 bit 0

bit 7 CPD: Data EEPROM Code Protection bit

1 = Data EEPROM not code-protected

0 = Data EEPROM code-protected

bit 6 CPB: Boot Block Code Protection bit

1 = Boot block (000000-0007FFh) not code-protected

0 = Boot block (000000-0007FFh) code-protected

bit 5-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 U-0 R/C-1 R/C-1 R/C-1 R/C-1

— — — —WRT3

(1) WRT2 WRT1 WRT0

bit 7 bit 0

bit 7-4 Unimplemented: Read as ‘0’

bit 3 WRT3: Write Protection bit(1)

1 = Block 3 (00C000-00FFFFh) not write-protected

0 = Block 3 (00C000-00FFFFh) write-protected

Note 1: Unimplemented in PIC18FX585 devices; maintain this bit set.

bit 2 WRT2: Write Protection bit

1 = Block 2 (008000-00BFFFh) not write-protected

0 = Block 2 (008000-00BFFFh) write-protected

bit 1 WRT1: Write Protection bit

1 = Block 1 (004000-007FFFh) not write-protected

0 = Block 1 (004000-007FFFh) write-protected

bit 0 WRT0: Write Protection bit

1 = Block 0 (000800-003FFFh) not write-protected

0 = Block 0 (000800-003FFFh) write-protected

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

R/C-1 R/C-1 R-1 U-0 U-0 U-0 U-0 U-0

WRTD WRTB WRTC(1) — — — — —

bit 7 bit 0

bit 7 WRTD: Data EEPROM Write Protection bit

1 = Data EEPROM not write-protected

0 = Data EEPROM write-protected

bit 6 WRTB: Boot Block Write Protection bit

1 = Boot block (000000-0007FFh) not write-protected

0 = Boot block (000000-0007FFh) write-protected

bit 5 WRTC: Configuration Register Write Protection bit(1)

1 = Configuration registers (300000-3000FFh) not write-protected

0 = Configuration registers (300000-3000FFh) write-protected

Note 1: This bit is read-only in normal execution mode; it can be written only in

Program mode.

bit 4-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

U-0 U-0 U-0 U-0 R/C-1 R/C-1 R/C-1 R/C-1

———— EBTR3(1) EBTR2 EBTR1 EBTR0

bit 7 bit 0

bit 7-4 Unimplemented: Read as ‘0’

bit 3 EBTR3: Table Read Protection bit(1)

1 = Block 3 (00C000-00FFFFh) not protected from table reads executed in other blocks

0 = Block 3 (00C000-00FFFFh) protected from table reads executed in other blocks

Note 1: Unimplemented in PIC18FX585 devices; maintain this bit set.

bit 2 EBTR2: Table Read Protection bit

1 = Block 2 (008000-00BFFFh) not protected from table reads executed in other blocks

0 = Block 2 (008000-00BFFFh) protected from table reads executed in other blocks

bit 1 EBTR1: Table Read Protection bit

1 = Block 1 (004000-007FFFh) not protected from table reads executed in other blocks

0 = Block 1 (004000-007FFFh) protected from table reads executed in other blocks

bit 0 EBTR0: Table Read Protection bit

1 = Block 0 (000800-003FFFh) not protected from table reads executed in other blocks

0 = Block 0 (000800-003FFFh) protected from table reads executed in other blocks

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

U-0 R/C-1 U-0 U-0 U-0 U-0 U-0 U-0

— EBTRB — — — — — —

bit 7 bit 0

bit 7 Unimplemented: Read as ‘0’

bit 6 EBTRB: Boot Block Table Read Protection bit

1 = Boot block (000000-0007FFh) not protected from table reads executed in other blocks

0 = Boot block (000000-0007FFh) protected from table reads executed in other blocks

bit 5-0 Unimplemented: Read as ‘0’

Legend:

R = Readable bit C = Clearable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

RRRRRRRR

DEV2 DEV1 DEV0 REV4 REV3 REV2 REV1 REV0

bit 7 bit 0

bit 7-5 DEV2:DEV0: Device ID bits

111 = PIC18F2585

110 = PIC18F2680

101 = PIC18F4585

100 = PIC18F4680

bit 4-0 REV4:REV0: Revision ID bits

These bits are used to indicate the device revision.

Legend:

R = Read-only bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

RRRRRRRR

DEV10 DEV9 DEV8 DEV7 DEV6 DEV5 DEV4 DEV3

bit 7 bit 0

bit 7-0 DEV10:DEV3: Device ID bits

These bits are used with the DEV2:DEV0 bits in the Device ID Register 1 to identify the

part number.

0000 1110 = PIC18F2585/2680/4585/4680 devices

Note: These values for DEV10:DEV3 may be shared with other devices. The specific

device is always identified by using the entire DEV10:DEV0 bit sequence.

Legend:

R = Read-only bit P = Programmable bit U = Unimplemented bit, read as ‘0’

-n = Value when device is unprogrammed u = Unchanged from programmed state

PIC18F2585/2680/4585/4680

24.2 Watchdog Timer (WDT)

For PIC18F2585/2680/4585/4680 devices, the WDT is

driven by the INTRC source. When the WDT is

enabled, the clock source is also enabled. The nominal

WDT period is 4 ms and has the same stability as the

INTRC oscillator.

The 4 ms period of the WDT is multiplied by a 16-bit

postscaler. Any output of the WDT postscaler is

selected by a multiplexer, controlled by bits in Configu-

ration Register 2H. Available periods range from 4 ms

to 131.072 seconds (2.18 minutes). The WDT and

postscaler are cleared when any of the following events

occur: a SLEEP or CLRWDT instruction is executed, the

IRCF bits (OSCCON<6:4>) are changed or a clock

failure has occurred.

24.2.1 CONTROL REGISTER

readable and writable register which contains a control

bit that allows software to override the WDT enable

Configuration bit, but only if the Configuration bit has

disabled the WDT.

FIGURE 24-1: WDT BLOCK DIAGRAM

Note 1: The CLRWDT and SLEEP instructions

clear the WDT and postscaler counts

when executed.

2: Changing the setting of the IRCF bits

(OSCCON<6:4>) clears the WDT and

postscaler counts.

3: When a CLRWDT instruction is executed,

the postscaler count will be cleared.

INTRC Source

WDT

Wake-up

Reset

WDT

WDT Counter

Programmable Postscaler

1:1 to 1:32,768

Enable WDT

WDTPS<3:0>

SWDTEN

WDTEN

CLRWDT

from Power

Reset

All Device Resets

Sleep

INTRC Control

÷128

Change on IRCF bits

Managed Modes

PIC18F2585/2680/4585/4680

TABLE 24-2: SUMMARY OF WATCHDOG TIMER REGISTERS

U-0 U-0 U-0 U-0 U-0 U-0 U-0 R/W-0

— — — — — — —SWDTEN

(1)

bit 7 bit 0

bit 7-1 Unimplemented: Read as ‘0’

bit 0 SWDTEN: Software Controlled Watchdog Timer Enable bit(1)

1 = Watchdog Timer is on

0 = Watchdog Timer is off

Note 1: This bit has no effect if the Configuration bit, WDTEN, is enabled.

Legend:

R = Readable bit W = Writable bit

U = Unimplemented bit, read as ‘0’ -n = Value at POR

Name Bit 7Bit 6Bit 5Bit 4Bit 3Bit 2Bit 1Bit 0

Reset

Values

on page

RCON IPEN SBOREN —RI TO PD POR BOR 48

WDTCON ———————SWDTEN50

Legend: — = unimplemented, read as ‘0’. Shaded cells are not used by the Watchdog Timer.

PIC18F2585/2680/4585/4680

24.3 Two-Speed Start-up

The Two-Speed Start-up feature helps to minimize the

latency period from oscillator start-up to code execution

by allowing the microcontroller to use the INTRC

oscillator as a clock source until the primary clock

source is available. It is enabled by setting the IESO

Configuration bit.

Two-Speed Start-up should be enabled only if the

primary oscillator mode is LP, XT, HS or HSPLL

(Crystal-based modes). Other sources do not require

an OST start-up delay; for these, Two-Speed Start-up

should be disabled.

When enabled, Resets and wake-ups from Sleep mode

cause the device to configure itself to run from the

internal oscillator block as the clock source, following

the time-out of the Power-up Timer after a Power-on

Reset is enabled. This allows almost immediate code

execution while the primary oscillator starts and the

OST is running. Once the OST times out, the device

automatically switches to PRI_RUN mode.

Because the OSCCON register is cleared on Reset

events, the INTOSC (or postscaler) clock source is not

initially available after a Reset event; the INTRC clock

is used directly at its base frequency. To use a higher

clock speed on wake-up, the INTOSC or postscaler

clock sources can be selected to provide a higher clock

speed by setting bits, IRCF2:IRCF0, immediately after

Reset. For wake-ups from Sleep, the INTOSC or

postscaler clock sources can be selected by setting the

IRCF2:IRCF0 bits prior to entering Sleep mode.

In all other power managed modes, Two-Speed Start-up

is not used. The device will be clocked by the currently

selected clock source until the primary clock source

becomes available. The setting of the IESO bit is

ignored.

24.3.1 SPECIAL CONSIDERATIONS FOR

USING TWO-SPEED START-UP

While using the INTRC oscillator in Two-Speed Start-up,

the device still obeys the normal command sequences

for entering power managed modes, including serial

SLEEP instructions (refer to Section 3.1.4 “Multiple

Sleep Commands”). In practice, this means that user

code can change the SCS1:SCS0 bit settings or issue

SLEEP instructions before the OST times out. This would

allow an application to briefly wake-up, perform routine

“housekeeping” tasks and return to Sleep before the

device starts to operate from the primary oscillator.

User code can also check if the primary clock source is

currently providing the device clocking by checking the

status of the OSTS bit (OSCCON<3>). If the bit is set,

the primary oscillator is providing the clock. Otherwise,

the internal oscillator block is providing the clock during

wake-up from Reset or Sleep mode.

FIGURE 24-2: TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL)

Q1 Q3 Q4

OSC1

Peripheral

Program PC PC + 2

INTOSC

PLL Clock

PC + 6

Output

Q3 Q4 Q1

CPU Clock

PC + 4

Clock

Counter

Q2 Q2 Q3

Note 1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale.

Wake from Interrupt Event

TPLL(1)

12 n-1n

Clock

OSTS bit Set

Transition

Multiplexer

TOST(1)

PIC18F2585/2680/4585/4680

24.4 Fail-Safe Clock Monitor

The Fail-Safe Clock Monitor (FSCM) allows the

microcontroller to continue operation in the event of an

external oscillator failure by automatically switching the

device clock to the internal oscillator block. The FSCM

function is enabled by setting the FCMEN

Configuration bit.

When FSCM is enabled, the INTRC oscillator runs at

all times to monitor clocks to peripherals and provide a

backup clock in the event of a clock failure. Clock

monitoring (shown in Figure 24-3) is accomplished by

creating a sample clock signal, which is the INTRC out-

put divided by 64. This allows ample time between

FSCM sample clocks for a peripheral clock edge to

occur. The peripheral device clock and the sample

clock are presented as inputs to the Clock Monitor latch

(CM). The CM is set on the falling edge of the device

clock source, but cleared on the rising edge of the

sample clock.

FIGURE 24-3: FSCM BLOCK DIAGRAM

Clock failure is tested for on the falling edge of the

sample clock. If a sample clock falling edge occurs

while CM is still set, a clock failure has been detected

(Figure 24-4). This causes the following:

• the FSCM generates an oscillator fail interrupt by

setting bit OSCFIF (PIR2<7>);

• the device clock source is switched to the internal

oscillator block (OSCCON is not updated to show

the current clock source – this is the fail-safe

condition); and

•the WDT is reset.

During switchover, the postscaler frequency from the

internal oscillator block may not be sufficiently stable for

timing sensitive applications. In these cases, it may be

desirable to select another clock configuration and enter

an alternate power managed mode. This can be done to

attempt a partial recovery or execute a controlled shut-

down. See Section 3.1.4 “Multiple Sleep Commands”

and Section 24.3.1 “Special Considerations for

Using Two-Speed Start-up” for more details.

To use a higher clock speed on wake-up, the INTOSC

or postscaler clock sources can be selected to provide

a higher clock speed by setting bits, IRCF2:IRCF0,

immediately after Reset. For wake-ups from Sleep, the

INTOSC or postscaler clock sources can be selected

by setting the IRCF2:IRCF0 bits prior to entering Sleep

mode.

The FSCM will detect failures of the primary or second-

ary clock sources only. If the internal oscillator block

fails, no failure would be detected, nor would any action

be possible.

24.4.1 FSCM AND THE WATCHDOG TIMER

Both the FSCM and the WDT are clocked by the

INTRC oscillator. Since the WDT operates with a

separate divider and counter, disabling the WDT has

no effect on the operation of the INTRC oscillator when

the FSCM is enabled.

As already noted, the clock source is switched to the

INTOSC clock when a clock failure is detected.

Depending on the frequency selected by the

IRCF2:IRCF0 bits, this may mean a substantial change

in the speed of code execution. If the WDT is enabled

with a small prescale value, a decrease in clock speed

allows a WDT time-out to occur and a subsequent

device Reset. For this reason, fail-safe clock events

also reset the WDT and postscaler, allowing it to start

timing from when execution speed was changed and

decreasing the likelihood of an erroneous time-out.

24.4.2 EXITING FAIL-SAFE OPERATION

The fail-safe condition is terminated by either a device

Reset or by entering a power managed mode. On

Reset, the controller starts the primary clock source

specified in Configuration Register 1H (with any

required start-up delays that are required for the

oscillator mode, such as OST or PLL timer). The

INTOSC multiplexer provides the device clock until the

primary clock source becomes ready (similar to a Two-

Speed Start-up). The clock source is then switched to

the primary clock (indicated by the OSTS bit in the

OSCCON register becoming set). The Fail-Safe Clock

Monitor then resumes monitoring the peripheral clock.

The primary clock source may never become ready

during start-up. In this case, operation is clocked by the

INTOSC multiplexer. The OSCCON register will remain

in its Reset state until a power managed mode is

entered.

Peripheral

INTRC ÷ 64

(32 μs) 488 Hz

(2.048 ms)

Clock Monitor

Latch (CM)

(edge-triggered)

Clock

Failure

Detected

Source

Clock

PIC18F2585/2680/4585/4680

FIGURE 24-4: FSCM TIMING DIAGRAM

24.4.3 FSCM INTERRUPTS IN POWER

MANAGED MODES

By entering a power managed mode, the clock

multiplexer selects the clock source selected by the

OSCCON register. Fail-Safe Monitoring of the power

managed clock source resumes in the power managed

mode.

If an oscillator failure occurs during power managed

operation, the subsequent events depend on whether

or not the oscillator failure interrupt is enabled. If

enabled (OSCFIF = 1), code execution will be clocked

by the INTOSC multiplexer. An automatic transition

back to the failed clock source will not occur.

If the interrupt is disabled, subsequent interrupts while

in Idle mode will cause the CPU to begin executing

instructions while being clocked by the INTOSC

source.

24.4.4 POR OR WAKE-UP FROM SLEEP

The FSCM is designed to detect oscillator failure at any

point after the device has exited Power-on Reset

(POR) or low-power Sleep mode. When the primary

device clock is EC, RC or INTRC modes, monitoring

can begin immediately following these events.

For oscillator modes involving a crystal or resonator

(HS, HSPLL, LP or XT), the situation is somewhat

different. Since the oscillator may require a start-up

time considerably longer than the FCSM sample clock

time, a false clock failure may be detected. To prevent

this, the internal oscillator block is automatically config-

ured as the device clock and functions until the primary

clock is stable (the OST and PLL timers have timed

out). This is identical to Two-Speed Start-up mode.

Once the primary clock is stable, the INTRC returns to

its role as the FSCM source.

As noted in Section 24.3.1 “Special Considerations

for Using Two-Speed Start-up”, it is also possible to

select another clock configuration and enter an alternate

power managed mode while waiting for the primary clock

to become stable. When the new power managed mode

is selected, the primary clock is disabled.

OSCFIF

CM Output

Device

Clock

Output

Sample Clock

Failure

Detected

Oscillator

Failure

Note: The device clock is normally at a much higher frequency than the sample clock. The relative frequencies in this

example have been chosen for clarity.

(Q)

CM Test CM Test CM Test

Note: The same logic that prevents false oscilla-

tor failure interrupts on POR, or wake from

Sleep, will also prevent the detection of

the oscillator’s failure to start at all follow-

ing these events. This can be avoided by

monitoring the OSTS bit and using a

timing routine to determine if the oscillator

is taking too long to start. Even so, no

oscillator failure interrupt will be flagged.

PIC18F2585/2680/4585/4680

24.5 Program Verification and

Code Protection

The overall structure of the code protection on the

PIC18 Flash devices differs significantly from other

PIC® devices.

The user program memory is divided into five blocks.

One of these is a boot block of 2 Kbytes. The remainder

of the memory is divided into four blocks on binary

boundaries.

Each of the five blocks has three code protection bits

associated with them. They are:

• Code-Protect bit (CPn)

• Write-Protect bit (WRTn)

• External Block Table Read bit (EBTRn)

Figure 24-5 shows the program memory organization

for 48 and 64-Kbyte devices and the specific code

protection bit associated with each block. The actual

locations of the bits are summarized in Table 24-3.

FIGURE 24-5: CODE-PROTECTED PROGRAM MEMORY FOR PIC18F2585/2680/4585/4680

TABLE 24-3: SUMMARY OF CODE PROTECTION REGISTERS

File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

300008h CONFIG5L ———— CP3* CP2 CP1 CP0

300009h CONFIG5H CPD CPB — — — — — —

30000Ah CONFIG6L ———— WRT3* WRT2 WRT1 WRT0

30000Bh CONFIG6H WRTD WRTB WRTC — — — — —

30000Ch CONFIG7L ———— EBTR3* EBTR2 EBTR1 EBTR0

30000Dh CONFIG7H — EBTRB — — — — — —

Legend: Shaded cells are unimplemented.

* Unimplemented in PIC18FX585 devices; maintain this bit set.

MEMORY SIZE/DEVICE

Block Code Protection

Controlled By:

48 Kbytes

(PIC18F2585/4585)

64 Kbytes

(PIC18F2680/4680)

Address

Range

Boot Block Boot Block 000000h

0007FFh CPB, WRTB, EBTRB

Block 0 Block 0

000800h

003FFFh

CP0, WRT0, EBTR0

Block 1 Block 1

004000h

007FFFh

CP1, WRT1, EBTR1

Block 2 Block 2

008000h

00B7FFh

CP2, WRT2, EBTR2

Unimplemented

Read ‘0’s Block 3

00C000h

00FFFFh

CP3, WRT3, EBTR3

Unimplemented

Read ‘0’s

Unimplemented

Read ‘0’s

010000h

1FFFFFh

(Unimplemented Memory Space)

PIC18F2585/2680/4585/4680

24.5.1 PROGRAM MEMORY

CODE PROTECTION

The program memory may be read to or written from

any location using the table read and table write

instructions. The device ID may be read with table

reads. The Configuration registers may be read and

written with the table read and table write instructions.

In normal execution mode, the CPn bits have no direct

effect. CPn bits inhibit external reads and writes. A

block of user memory may be protected from table

writes if the WRTn Configuration bit is ‘0’. The EBTRn

bits control table reads. For a block of user memory

with the EBTRn bit set to ‘0’, a table read instruction

that executes from within that block is allowed to read.

A table read instruction that executes from a location

outside of that block is not allowed to read and will

result in reading ‘0’s. Figures 24-6 through 24-8

illustrate table write and table read protection.

FIGURE 24-6: TABLE WRITE (WRTn) DISALLOWED

Note: Code protection bits may only be written to

a ‘0’ from a ‘1’ state. It is not possible to

write a ‘1’ to a bit in the ‘0’ state. Code

protection bits are only set to ‘1’ by a full

chip erase or block erase function. The full

chip erase and block erase functions can

only be initiated via ICSP or an external

programmer.

000000h

0007FFh

000800h

003FFFh

004000h

007FFFh

008000h

00BFFFh

00C000h

00FFFFh

WRTB, EBTRB = 11

WRT0, EBTR0 = 01

WRT1, EBTR1 = 11

WRT2, EBTR2 = 11

WRT3, EBTR3 = 11

TBLWT*

TBLPTR = 0008FFh

PC = 003FFEh

TBLWT*

PC = 00BFFEh

Results: All table writes disabled to Blockn whenever WRTn = 0.

PIC18F2585/2680/4585/4680

FIGURE 24-7: EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED

FIGURE 24-8: EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED

WRTB, EBTRB = 11

WRT0, EBTR0 = 10

WRT1, EBTR1 = 11

WRT2, EBTR2 = 11

WRT3, EBTR3 = 11

TBLRD*

TBLPTR = 0008FFh

PC = 007FFEh

Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0.

TABLAT register returns a value of ‘0’.

000000h

0007FFh

000800h

003FFFh

004000h

007FFFh

008000h

00BFFFh

00C000h

00FFFFh

WRTB, EBTRB = 11

WRT0, EBTR0 = 10

WRT1, EBTR1 = 11

WRT2, EBTR2 = 11

WRT3, EBTR3 = 11

TBLRD*

TBLPTR = 0008FFh

PC = 003FFEh

Results: Table reads permitted within Blockn, even when EBTRBn = 0.

TABLAT register returns the value of the data at the location TBLPTR.

000000h

0007FFh

000800h

003FFFh

004000h

007FFFh

008000h

00BFFFh

00C000h

00FFFFh

PIC18F2585/2680/4585/4680

24.5.2 DATA EEPROM

CODE PROTECTION

The entire data EEPROM is protected from external

reads and writes by two bits: CPD and WRTD. CPD

inhibits external reads and writes of data EEPROM.

WRTD inhibits internal and external writes to data

EEPROM. The CPU can continue to read and write

data EEPROM regardless of the protection bit settings.

24.5.3 CONFIGURATION REGISTER

PROTECTION

The Configuration registers can be write-protected.

The WRTC bit controls protection of the Configuration

registers. In normal execution mode, the WRTC bit is

readable only. WRTC can only be written via ICSP or

an external programmer.

24.6 ID Locations

Eight memory locations (200000h-200007h) are

designated as ID locations, where the user can store

checksum or other code identification numbers. These

locations are both readable and writable during normal

execution through the TBLRD and TBLWT instructions

or during program/verify. The ID locations can be read

when the device is code-protected.

24.7 In-Circuit Serial Programming

PIC18F2585/2680/4585/4680 microcontrollers can be

serially programmed while in the end application circuit.

This is simply done with two lines for clock and data

and three other lines for power, ground and the

programming voltage. This allows customers to

manufacture boards with unprogrammed devices and

then program the microcontroller just before shipping

the product. This also allows the most recent firmware

or a custom firmware to be programmed.

24.8 In-Circuit Debugger

When the DEBUG Configuration bit is programmed to

a ‘0’, the In-Circuit Debugger functionality is enabled.

This function allows simple debugging functions when

used with MPLAB® IDE. When the microcontroller has

this feature enabled, some resources are not available

for general use. Table 24-4 shows which resources are

required by the background debugger.

TABLE 24-4: DEBUGGER RESOURCES

To use the In-Circuit Debugger function of the micro-

controller, the design must implement In-Circuit Serial

Programming connections to MCLR/VPP/RE3, VDD,

VSS, RB7 and RB6. This will interface to the In-Circuit

debugger module available from Microchip or one of

the third party development tool companies.

24.9 Single-Supply ICSP Programming

The LVP Configuration bit enables Single-Supply ICSP

programming (formerly known as

Low-Voltage ICSP

Programming

LVP

). When Single-Supply Program-

ming is enabled, the microcontroller can be programmed

without requiring high voltage being applied to the

MCLR/VPP/RE3 pin, but the RB5/KBI1/PGM pin is then

dedicated to controlling Program mode entry and is not

available as a general purpose I/O pin.

While programming using Single-Supply Programming,

VDD is applied to the MCLR/VPP/RE3 pin as in normal

execution mode. To enter Programming mode, VDD is

applied to the PGM pin.

If Single-Supply ICSP Programming mode will not be

used, the LVP bit can be cleared. RB5/KBI1/PGM then

becomes available as the digital I/O pin, RB5. The LVP

bit may be set or cleared only when using standard

high-voltage programming (VIHH applied to the MCLR/

VPP/RE3 pin). Once LVP has been disabled, only the

standard high-voltage programming is available and

must be used to program the device.

Memory that is not code-protected can be erased using

either a block erase, or erased row by row, then written

at any specified VDD. If code-protected memory is to be

erased, a block erase is required. If a block erase is to

be performed when using Low-Voltage Programming,

the device must be supplied with VDD of 4.5V to 5.5V.

I/O pins: RB6, RB7

Stack: 2 levels

Note: Memory resources listed in MPLAB® IDE.

Note 1: High-voltage programming is always avail-

able, regardless of the state of the LVP bit,

by applying VIHH to the MCLR pin.

2: While in Low-Voltage ICSP Programming

mode, the RB5 pin can no longer be used

as a general purpose I/O pin and should

be held low during normal operation.

3: When using Low-Voltage ICSP Program-

ming (LVP) and the pull-ups on PORTB

are enabled, bit 5 in the TRISB register

must be cleared to disable the pull-up on

RB5 and ensure the proper operation of

the device.

4: If the device Master Clear is disabled,

verify that either of the following is done to

ensure proper entry into ICSP mode:

a) disable Low-Voltage Programming

(CONFIG4l<2> = 0); or

b) make certain that RB5/PGM is held

low during entry into ICSP.

PIC18F2585/2680/4585/4680

25.0 INSTRUCTION SET SUMMARY

PIC18F2585/2680/4585/4680 devices incorporate the

standard set of 75 PIC18 core instructions, as well as

an extended set of 8 new instructions, for the optimiza-

tion of code that is recursive or that utilizes a software

stack. The extended set is discussed later in this

section.

25.1 Standard Instruction Set

The standard PIC18 instruction set adds many

enhancements to the previous PIC® MCU instruction

sets, while maintaining an easy migration from these

PIC MCU instruction sets. Most instructions are a

single program memory word (16 bits), but there are

four instructions that require two program memory

locations.

Each single-word instruction is a 16-bit word divided

into an opcode, which specifies the instruction type and

one or more operands, which further specify the

operation of the instruction.

The instruction set is highly orthogonal and is grouped

into four basic categories:

•Byte-oriented operations

•Bit-oriented operations

•Literal operations

•Control operations

The PIC18 instruction set summary in Table 25-2 lists

byte-oriented, bit-oriented, literal and control

operations. Table 25-1 shows the opcode field

descriptions.

Most byte-oriented instructions have three operands:

1. The file register (specified by ‘f’)

2. The destination of the result (specified by ‘d’)

3. The accessed memory (specified by ‘a’)

The file register designator ‘f’ specifies which file

designator ‘d’ specifies where the result of the opera-

tion is to be placed. If ‘d’ is zero, the result is placed in

the WREG register. If ‘d’ is one, the result is placed in

the file register specified in the instruction.

All bit-oriented instructions have three operands:

1. The file register (specified by ‘f’)

2. The bit in the file register (specified by ‘b’)

3. The accessed memory (specified by ‘a’)

The bit field designator ‘b’ selects the number of the bit

affected by the operation, while the file register

designator ‘f’ represents the number of the file in which

the bit is located.

The literal instructions may use some of the following

operands:

• A literal value to be loaded into a file register

(specified by ‘k’)

• The desired FSR register to load the literal value

into (specified by ‘f’)

• No operand required

(specified by ‘—’)

The control instructions may use some of the following

operands:

• A program memory address (specified by ‘n’)

• The mode of the CALL or RETURN instructions

(specified by ‘s’)

• The mode of the table read and table write

instructions (specified by ‘m’)

• No operand required

(specified by ‘—’)

All instructions are a single word, except for four

double-word instructions. These instructions were

made double-word to contain the required information

in 32 bits. In the second word, the 4 MSbs are ‘1’s. If

this second word is executed as an instruction (by

itself), it will execute as a NOP.

All single-word instructions are executed in a single

instruction cycle, unless a conditional test is true or the

program counter is changed as a result of the instruc-

tion. In these cases, the execution takes two instruction

cycles with the additional instruction cycle(s) executed

as a NOP.

The double-word instructions execute in two instruction

cycles.

One instruction cycle consists of four oscillator periods.

Thus, for an oscillator frequency of 4 MHz, the normal

instruction execution time is 1 μs. If a conditional test is

true, or the program counter is changed as a result of

an instruction, the instruction execution time is 2 μs.

Two-word branch instructions (if true) would take 3 μs.

Figure 25-1 shows the general formats that the instruc-

tions can have. All examples use the convention ‘nnh’

to represent a hexadecimal number.

The Instruction Set Summary, shown in Table 25-2,

lists the standard instructions recognized by the

Microchip MPASM™ Assembler.

Section 25.1.1 “Standard Instruction Set” provides

a description of each instruction.

PIC18F2585/2680/4585/4680

TABLE 25-1: OPCODE FIELD DESCRIPTIONS

Field Description

aRAM access bit

a = 0: RAM location in Access RAM (BSR register is ignored)

a = 1: RAM bank is specified by BSR register

bbb Bit address within an 8-bit file register (0 to 7).

BSR Bank Select Register. Used to select the current RAM bank.

C, DC, Z, OV, N ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative.

dDestination select bit

d = 0: store result in WREG

d = 1: store result in file register f

dest Destination: either the WREG register or the specified register file location.

f8-bit Register file address (00h to FFh), or 2-bit FSR designator (0h to 3h).

fs12-bit Register file address (000h to FFFh). This is the source address.

fd12-bit Register file address (000h to FFFh). This is the destination address.

GIE Global Interrupt Enable bit.

kLiteral field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value)

label Label name

mm The mode of the TBLPTR register for the table read and table write instructions.

Only used with table read and table write instructions:

*No change to register (such as TBLPTR with table reads and writes)

*+ Post-Increment register (such as TBLPTR with table reads and writes)

*- Post-Decrement register (such as TBLPTR with table reads and writes)

+* Pre-Increment register (such as TBLPTR with table reads and writes)

nThe relative address (2’s complement number) for relative branch instructions or the direct address for

Call/Branch and Return instructions

PC Program Counter.

PCL Program Counter Low Byte.

PCH Program Counter High Byte.

PCLATH Program Counter High Byte Latch.

PCLATU Program Counter Upper Byte Latch.

PD Power-down bit.

PRODH Product of Multiply High Byte.

PRODL Product of Multiply Low Byte.

sFast Call/Return mode select bit

s = 0: do not update into/from shadow registers

s = 1: certain registers loaded into/from shadow registers (Fast mode)

TBLPTR 21-bit Table Pointer (points to a Program Memory location).

TABLAT 8-bit Table Latch.

TO Time-out bit.

TOS Top-of-Stack.

uUnused or unchanged.

WDT Watchdog Timer.

WREG Working register (accumulator).

xDon’t care (‘0’ or ‘1’). The assembler will generate code with x = 0. It is the recommended form of use for

compatibility with all Microchip software tools.

zs7-bit offset value for indirect addressing of register files (source).

zd7-bit offset value for indirect addressing of register files (destination).

{ } Optional argument.

[text] Indicates an indexed address.

(text) The contents of text.

[expr]<n> Specifies bit n of the register indicated by the pointer expr.

→Assigned to.

< > Register bit field.

∈In the set of.

italics User defined term (font is Courier).

PIC18F2585/2680/4585/4680

FIGURE 25-1: GENERAL FORMAT FOR INSTRUCTIONS

Byte-oriented file register operations

15 10 9 8 7 0

d = 0 for result destination to be WREG register

OPCODE d a f (FILE #)

d = 1 for result destination to be file register (f)

a = 0 to force Access Bank

Bit-oriented file register operations

15 12 11 9 8 7 0

OPCODE b (BIT #) a f (FILE #)

b = 3-bit position of bit in file register (f)

Literal operations

15 8 7 0

OPCODE k (literal)

k = 8-bit immediate value

Byte to Byte move operations (2-word)

15 12 11 0

OPCODE f (Source FILE #)

CALL, GOTO and Branch operations

15 8 7 0

OPCODE n<7:0> (literal)

n = 20-bit immediate value

a = 1 for BSR to select bank

f = 8-bit file register address

a = 0 to force Access Bank

a = 1 for BSR to select bank

f = 8-bit file register address

15 12 11 0

1111 n<19:8> (literal)

15 12 11 0

1111 f (Destination FILE #)

f = 12-bit file register address

Control operations

Example Instruction

ADDWF MYREG, W, B

MOVFF MYREG1, MYREG2

BSF MYREG, bit, B

MOVLW 7Fh

GOTO Label

15 8 7 0

OPCODE n<7:0> (literal)

15 12 11 0

1111 n<19:8> (literal)

CALL MYFUNC

15 11 10 0

OPCODE n<10:0> (literal)

S = Fast bit

BRA MYFUNC

15 8 7 0

OPCODE n<7:0> (literal) BC MYFUNC

PIC18F2585/2680/4585/4680

TABLE 25-2: PIC18FXXXX INSTRUCTION SET

Mnemonic,

Operands Description Cycles

16-Bit Instruction Word Status

Affected Notes

MSb LSb

BYTE-ORIENTED OPERATIONS

ADDWF

ADDWFC

ANDWF

CLRF

COMF

CPFSEQ

CPFSGT

CPFSLT

DECF

DECFSZ

DCFSNZ

INCF

INCFSZ

INFSNZ

IORWF

MOVF

MOVFF

MOVWF

MULWF

NEGF

RLCF

RLNCF

RRCF

RRNCF

SETF

SUBFWB

SUBWF

SUBWFB

SWAPF

TSTFSZ

XORWF

f, d, a

f, a

f, d, a

f, a

f, d, a

fs, fd

f, a

f, d, a

f, a

f, d, a

f, a

f, d, a

Add WREG and f

Add WREG and Carry bit to f

AND WREG with f

Clear f

Complement f

Compare f with WREG, skip =

Compare f with WREG, skip >

Compare f with WREG, skip <

Decrement f

Decrement f, Skip if 0

Decrement f, Skip if Not 0

Increment f

Increment f, Skip if 0

Increment f, Skip if Not 0

Inclusive OR WREG with f

Move f

Move fs (source) to 1st word

fd (destination)2nd word

Move WREG to f

Multiply WREG with f

Negate f

Rotate Left f through Carry

Rotate Left f (No Carry)

Rotate Right f through Carry

Rotate Right f (No Carry)

Set f

Subtract f from WREG with

borrow

Subtract WREG from f

Subtract WREG from f with

borrow

Swap nibbles in f

Test f, skip if 0

Exclusive OR WREG with f

1 (2 or 3)

0010

0001

0110

0001

0110

0000

0010

0100

0010

0011

0100

0001

0101

1100

1111

0110

0000

0110

0011

0100

0011

0100

0110

0101

0011

0110

0001

01da

00da

01da

101a

11da

001a

010a

000a

01da

11da

10da

11da

10da

00da

ffff

111a

001a

110a

01da

00da

100a

01da

11da

10da

011a

10da

ffff

C, DC, Z, OV, N

Z, N

None

C, DC, Z, OV, N

None

C, DC, Z, OV, N

None

Z, N

None

C, DC, Z, OV, N

C, Z, N

Z, N

C, Z, N

Z, N

None

C, DC, Z, OV, N

None

Z, N

1, 2

1,2

1, 2

1, 2, 3, 4

1, 2

1, 2, 3, 4

1, 2

Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that

value present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is

driven low by an external device, the data will be written back with a ‘0’.

2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared

if assigned.

3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second

cycle is executed as a NOP.

4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP

unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all

program memory locations have a valid instruction.

5: If the table write starts the write cycle to internal memory, the write will continue until terminated.

PIC18F2585/2680/4585/4680

BIT-ORIENTED OPERATIONS

BCF

BSF

BTFSC

BTFSS

BTG

f, b, a

Bit Clear f

Bit Set f

Bit Test f, Skip if Clear

Bit Test f, Skip if Set

Bit Toggle f

1 (2 or 3)

1001

1000

1011

1010

0111

bbba

ffff

None

1, 2

3, 4

1, 2

CONTROL OPERATIONS

BNC

BNN

BNOV

BNZ

BOV

BRA

CALL

CLRWDT

DAW

GOTO

NOP

POP

PUSH

RCALL

RESET

RETFIE

RETLW

RETURN

SLEEP

n, s

—

Branch if Carry

Branch if Negative

Branch if Not Carry

Branch if Not Negative

Branch if Not Overflow

Branch if Not Zero

Branch if Overflow

Branch Unconditionally

Branch if Zero

Call subroutine1st word

2nd word

Clear Watchdog Timer

Decimal Adjust WREG

Go to address 1st word

2nd word

No Operation

Pop top of return stack (TOS)

Push top of return stack (TOS)

Relative Call

Software device Reset

Return from interrupt enable

Return with literal in WREG

Return from Subroutine

Go into Standby mode

1 (2)

1110

1101

1110

1111

0000

1110

1111

0000

1111

0000

1101

0000

0010

0110

0011

0111

0101

0001

0100

0nnn

0000

110s

kkkk

0000

1111

kkkk

0000

xxxx

0000

1nnn

0000

1100

0000

nnnn

kkkk

0000

kkkk

0000

xxxx

0000

nnnn

1111

0001

kkkk

0001

0000

nnnn

kkkk

0100

0111

kkkk

0000

xxxx

0110

0101

nnnn

1111

000s

kkkk

001s

0011

None

TO, PD

None

All

GIE/GIEH,

PEIE/GIEL

None

TO, PD

TABLE 25-2: PIC18FXXXX INSTRUCTION SET (CONTINUED)

Mnemonic,

Operands Description Cycles

16-Bit Instruction Word Status

Affected Notes

MSb LSb

Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that

value present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is

driven low by an external device, the data will be written back with a ‘0’.

2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared

if assigned.

3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second

cycle is executed as a NOP.

4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP

unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all

program memory locations have a valid instruction.

5: If the table write starts the write cycle to internal memory, the write will continue until terminated.

PIC18F2585/2680/4585/4680

LITERAL OPERATIONS

ADDLW

ANDLW

IORLW

LFSR

MOVLB

MOVLW

MULLW

RETLW

SUBLW

XORLW

f, k

Add literal and WREG

AND literal with WREG

Inclusive OR literal with WREG

Move literal (12-bit) 2nd word

to FSR(f) 1st word

Move literal to BSR<3:0>

Move literal to WREG

Multiply literal with WREG

Return with literal in WREG

Subtract WREG from literal

Exclusive OR literal with WREG

0000

1110

1111

0000

1111

1011

1001

1110

0000

0001

1110

1101

1100

1000

1010

kkkk

00ff

kkkk

0000

kkkk

C, DC, Z, OV, N

Z, N

None

C, DC, Z, OV, N

Z, N

DATA MEMORY ↔ PROGRAM MEMORY OPERATIONS

TBLRD*

TBLRD*+

TBLRD*-

TBLRD+*

TBLWT*

TBLWT*+

TBLWT*-

TBLWT+*

Table Read

Table Read with post-increment

Table Read with post-decrement

Table Read with pre-increment

Table Write

Table Write with post-increment

Table Write with post-decrement

Table Write with pre-increment

0000

1000

1001

1010

1011

1100

1101

1110

1111

None

TABLE 25-2: PIC18FXXXX INSTRUCTION SET (CONTINUED)

Mnemonic,

Operands Description Cycles

16-Bit Instruction Word Status

Affected Notes

MSb LSb

Note 1: When a Port register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that

value present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is

driven low by an external device, the data will be written back with a ‘0’.

2: If this instruction is executed on the TMR0 register (and where applicable, ‘d’ = 1), the prescaler will be cleared

if assigned.

3: If Program Counter (PC) is modified or a conditional test is true, the instruction requires two cycles. The second

cycle is executed as a NOP.

4: Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP

unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all

program memory locations have a valid instruction.

5: If the table write starts the write cycle to internal memory, the write will continue until terminated.

PIC18F2585/2680/4585/4680

25.1.1 STANDARD INSTRUCTION SET

ADDLW ADD Literal to W

Syntax: ADDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) + k → W

Status Affected: N, OV, C, DC, Z

Encoding: 0000 1111 kkkk kkkk

Description: The contents of W are added to the

8-bit literal ‘k’ and the result is placed

in W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to W

Example: ADDLW 15h

Before Instruction

W = 10h

After Instruction

W = 25h

ADDWF ADD W to f

Syntax: ADDWF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) + (f) → dest

Status Affected: N, OV, C, DC, Z

Encoding: 0010 01da ffff ffff

Description: Add W to register ‘f’. If ‘d’ is ‘0’, the

result is stored in W. If ‘d’ is ‘1’, the

result is stored back in register ‘f’

(default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: ADDWF REG, 0, 0

Before Instruction

W = 17h

REG = 0C2h

After Instruction

W = 0D9h

REG = 0C2h

Note: All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in

symbolic addressing. If a label is used, the instruction format then becomes: {label} instruction argument(s).

PIC18F2585/2680/4585/4680

ADDWFC ADD W and Carry bit to f

Syntax: ADDWFC f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) + (f) + (C) → dest

Status Affected: N,OV, C, DC, Z

Encoding: 0010 00da ffff ffff

Description: Add W, the Carry flag and data memory

location ‘f’. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed in data memory

location ‘f’.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: ADDWFC REG, 0, 1

Before Instruction

Carry bit = 1

REG = 02h

W=4Dh

After Instruction

Carry bit = 0

REG = 02h

W = 50h

ANDLW AND Literal with W

Syntax: ANDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .AND. k → W

Status Affected: N, Z

Encoding: 0000 1011 kkkk kkkk

Description: The contents of W are ANDed with the

8-bit literal ‘k’. The result is placed in W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal

‘k’

Process

Data

Write to W

Example: ANDLW 05Fh

Before Instruction

W=A3h

After Instruction

W = 03h

PIC18F2585/2680/4585/4680

ANDWF AND W with f

Syntax: ANDWF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) .AND. (f) → dest

Status Affected: N, Z

Encoding: 0001 01da ffff ffff

Description: The contents of W are AND’ed with

in W. If ‘d’ is ‘1’, the result is stored back

in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: ANDWF REG, 0, 0

Before Instruction

W = 17h

REG = C2h

After Instruction

W = 02h

REG = C2h

BC Branch if Carry

Syntax: BC n

Operands: -128 ≤ n ≤ 127

Operation: if Carry bit is ‘1’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0010 nnnn nnnn

Description: If the Carry bit is ‘1’, then the program

will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BC 5

Before Instruction

PC = address (HERE)

After Instruction

If Carry = 1;

PC = address (HERE + 12)

If Carry = 0;

PC = address (HERE + 2)

PIC18F2585/2680/4585/4680

BCF Bit Clear f

Syntax: BCF f, b {,a}

Operands: 0 ≤ f ≤ 255

0 ≤ b ≤ 7

a ∈ [0,1]

Operation: 0 → f

Status Affected: None

Encoding: 1001 bbba ffff ffff

Description: Bit ‘b’ in register ‘f’ is cleared.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: BCF FLAG_REG, 7, 0

Before Instruction

FLAG_REG = C7h

After Instruction

FLAG_REG = 47h

BN Branch if Negative

Syntax: BN n

Operands: -128 ≤ n ≤ 127

Operation: if Negative bit is ‘1’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0110 nnnn nnnn

Description: If the Negative bit is ‘1’, then the

program will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BN Jump

Before Instruction

PC = address (HERE)

After Instruction

If Negative = 1;

PC = address (Jump)

If Negative = 0;

PC = address (HERE + 2)

PIC18F2585/2680/4585/4680

BNC Branch if Not Carry

Syntax: BNC n

Operands: -128 ≤ n ≤ 127

Operation: if Carry bit is ‘0’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0011 nnnn nnnn

Description: If the Carry bit is ‘0’, then the program

will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will

have incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BNC Jump

Before Instruction

PC = address (HERE)

After Instruction

If Carry = 0;

PC = address (Jump)

If Carry = 1;

PC = address (HERE + 2)

BNN Branch if Not Negative

Syntax: BNN n

Operands: -128 ≤ n ≤ 127

Operation: if Negative bit is ‘0’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0111 nnnn nnnn

Description: If the Negative bit is ‘0’, then the

program will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BNN Jump

Before Instruction

PC = address (HERE)

After Instruction

If Negative = 0;

PC = address (Jump)

If Negative = 1;

PC = address (HERE + 2)

PIC18F2585/2680/4585/4680

BNOV Branch if Not Overflow

Syntax: BNOV n

Operands: -128 ≤ n ≤ 127

Operation: if Overflow bit is ‘0’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0101 nnnn nnnn

Description: If the Overflow bit is ‘0’, then the

program will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BNOV Jump

Before Instruction

PC = address (HERE)

After Instruction

If Overflow = 0;

PC = address (Jump)

If Overflow = 1;

PC = address (HERE + 2)

BNZ Branch if Not Zero

Syntax: BNZ n

Operands: -128 ≤ n ≤ 127

Operation: if Zero bit is ‘0’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0001 nnnn nnnn

Description: If the Zero bit is ‘0’, then the program

will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BNZ Jump

Before Instruction

PC = address (HERE)

After Instruction

If Zero = 0;

PC = address (Jump)

If Zero = 1;

PC = address (HERE + 2)

PIC18F2585/2680/4585/4680

BRA Unconditional Branch

Syntax: BRA n

Operands: -1024 ≤ n ≤ 1023

Operation: (PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1101 0nnn nnnn nnnn

Description: Add the 2’s complement number ‘2n’ to

the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is a

two-cycle instruction.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

Example: HERE BRA Jump

Before Instruction

PC = address (HERE)

After Instruction

PC = address (Jump)

BSF Bit Set f

Syntax: BSF f, b {,a}

Operands: 0 ≤ f ≤ 255

0 ≤ b ≤ 7

a ∈ [0,1]

Operation: 1 → f

Status Affected: None

Encoding: 1000 bbba ffff ffff

Description: Bit ‘b’ in register ‘f’ is set.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: BSF FLAG_REG, 7, 1

Before Instruction

FLAG_REG = 0Ah

After Instruction

FLAG_REG = 8Ah

PIC18F2585/2680/4585/4680

BTFSC Bit Test File, Skip if Clear

Syntax: BTFSC f, b {,a}

Operands: 0 ≤ f ≤ 255

0 ≤ b ≤ 7

a ∈ [0,1]

Operation: skip if (f) = 0

Status Affected: None

Encoding: 1011 bbba ffff ffff

Description: If bit ‘b’ in register ‘f’ is ‘0’, then the next

instruction is skipped. If bit ‘b’ is ‘0’, then

the next instruction fetched during the

current instruction execution is discarded

and a NOP is executed instead, making

this a two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected. If

‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction set

is enabled, this instruction operates in

Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh).

See Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE

FALSE

TRUE

BTFSC

FLAG, 1, 0

Before Instruction

PC = address (HERE)

After Instruction

If FLAG<1> = 0;

PC = address (TRUE)

If FLAG<1> = 1;

PC = address (FALSE)

BTFSS Bit Test File, Skip if Set

Syntax: BTFSS f, b {,a}

Operands: 0 ≤ f ≤ 255

0 ≤ b < 7

a ∈ [0,1]

Operation: skip if (f) = 1

Status Affected: None

Encoding: 1010 bbba ffff ffff

Description: If bit ‘b’ in register ‘f’ is ‘1’, then the next

instruction is skipped. If bit ‘b’ is ‘1’, then

the next instruction fetched during the

current instruction execution is discarded

and a NOP is executed instead, making

this a two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected. If

‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh).

See Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE

FALSE

TRUE

BTFSS

FLAG, 1, 0

Before Instruction

PC = address (HERE)

After Instruction

If FLAG<1> = 0;

PC = address (FALSE)

If FLAG<1> = 1;

PC = address (TRUE)

PIC18F2585/2680/4585/4680

BTG Bit Toggle f

Syntax: BTG f, b {,a}

Operands: 0 ≤ f ≤ 255

0 ≤ b < 7

a ∈ [0,1]

Operation: (f) → f

Status Affected: None

Encoding: 0111 bbba ffff ffff

Description: Bit ‘b’ in data memory location ‘f’ is

inverted.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: BTG PORTC, 4, 0

Before Instruction:

PORTC = 0111 0101 [75h]

After Instruction:

PORTC = 0110 0101 [65h]

BOV Branch if Overflow

Syntax: BOV n

Operands: -128 ≤ n ≤ 127

Operation: if Overflow bit is ‘1’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0100 nnnn nnnn

Description: If the Overflow bit is ‘1’, then the

program will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will

have incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BOV Jump

Before Instruction

PC = address (HERE)

After Instruction

If Overflow = 1;

PC = address (Jump)

If Overflow = 0;

PC = address (HERE + 2)

PIC18F2585/2680/4585/4680

BZ Branch if Zero

Syntax: BZ n

Operands: -128 ≤ n ≤ 127

Operation: if Zero bit is ‘1’

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1110 0000 nnnn nnnn

Description: If the Zero bit is ‘1’, then the program

will branch.

The 2’s complement number ‘2n’ is

added to the PC. Since the PC will have

incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is then a

two-cycle instruction.

Words: 1

Cycles: 1(2)

Q Cycle Activity:

If Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

Write to PC

operation

If No Jump:

Q1 Q2 Q3 Q4

Decode Read literal

‘n’

Process

Data

operation

Example: HERE BZ Jump

Before Instruction

PC = address (HERE)

After Instruction

If Zero = 1;

PC = address (Jump)

If Zero = 0;

PC = address (HERE + 2)

CALL Subroutine Call

Syntax: CALL k {,s}

Operands: 0 ≤ k ≤ 1048575

s ∈ [0,1]

Operation: (PC) + 4 → TOS,

k → PC<20:1>,

if s = 1

(W) → WS,

(STATUS) → STATUSS,

(BSR) → BSRS

Status Affected: None

Encoding:

1st word (k<7:0>)

2nd word(k<19:8>)

1110

1111

110s

k19kkk

k7kkk

kkkk

kkkk0

kkkk8

Description: Subroutine call of entire 2-Mbyte

memory range. First, return address

(PC + 4) is pushed onto the return

stack. If ‘s’ = 1, the W, STATUS and

BSR registers are also pushed into their

respective shadow registers, WS,

STATUSS and BSRS. If ‘s’ = 0, no

update occurs (default). Then, the

20-bit value ‘k’ is loaded into PC<20:1>.

CALL is a two-cycle instruction.

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal

‘k’<7:0>,

Push PC to

stack

Read literal

‘k’<19:8>,

Write to PC

operation

Example: HERE CALL THERE, 1

Before Instruction

PC = address (HERE)

After Instruction

PC = address (THERE)

TOS = address (HERE + 4)

WS = W

BSRS = BSR

STATUSS= STATUS

PIC18F2585/2680/4585/4680

CLRF Clear f

Syntax: CLRF f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: 000h → f

1 → Z

Status Affected: Z

Encoding: 0110 101a ffff ffff

Description: Clears the contents of the specified

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: CLRF FLAG_REG,1

Before Instruction

FLAG_REG = 5Ah

After Instruction

FLAG_REG = 00h

CLRWDT Clear Watchdog Timer

Syntax: CLRWDT

Operands: None

Operation: 000h → WDT,

000h → WDT postscaler,

1 → TO,

1 → PD

Status Affected: TO, PD

Encoding: 0000 0000 0000 0100

Description: CLRWDT instruction resets the

Watchdog Timer. It also resets the

postscaler of the WDT. Status bits TO

and PD are set.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

Process

Data

operation

Example: CLRWDT

Before Instruction

WDT Counter = ?

After Instruction

WDT Counter = 00h

WDT Postscaler = 0

TO =1

PD =1

PIC18F2585/2680/4585/4680

COMF Complement f

Syntax: COMF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: → dest

Status Affected: N, Z

Encoding: 0001 11da ffff ffff

Description: The contents of register ‘f’ are

complemented. If ‘d’ is ‘1’, the result is

stored in W. If ‘d’ is ‘0’, the result is

stored back in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: COMF REG, 0, 0

Before Instruction

REG = 13h

After Instruction

REG = 13h

W=ECh

(f)

CPFSEQ Compare f with W, Skip if f = W

Syntax: CPFSEQ f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: (f) – (W),

skip if (f) = (W)

(unsigned comparison)

Status Affected: None

Encoding: 0110 001a ffff ffff

Description: Compares the contents of data memory

location ‘f’ to the contents of W by

performing an unsigned subtraction.

If ‘f’ = W, then the fetched instruction is

discarded and a NOP is executed

instead, making this a two-cycle

instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘0’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE CPFSEQ REG, 0

NEQUAL :

EQUAL :

Before Instruction

PC Address = HERE

W=?

REG = ?

After Instruction

If REG = W;

PC = Address (EQUAL)

If REG ≠ W;

PC = Address (NEQUAL)

PIC18F2585/2680/4585/4680

CPFSGT Compare f with W, Skip if f > W

Syntax: CPFSGT f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: (f) − (W),

skip if (f) > (W)

(unsigned comparison)

Status Affected: None

Encoding: 0110 010a ffff ffff

Description: Compares the contents of data memory

location ‘f’ to the contents of the W by

performing an unsigned subtraction.

If the contents of ‘f’ are greater than the

contents of WREG, then the fetched

instruction is discarded and a NOP is

executed instead, making this a

two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE CPFSGT REG, 0

NGREATER :

GREATER :

Before Instruction

PC = Address (HERE)

W= ?

After Instruction

If REG > W;

PC = Address (GREATER)

If REG ≤ W;

PC = Address (NGREATER)

CPFSLT Compare f with W, Skip if f < W

Syntax: CPFSLT f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: (f) – (W),

skip if (f) < (W)

(unsigned comparison)

Status Affected: None

Encoding: 0110 000a ffff ffff

Description: Compares the contents of data memory

location ‘f’ to the contents of W by

performing an unsigned subtraction.

If the contents of ‘f’ are less than the

contents of W, then the fetched

instruction is discarded and a NOP is

executed instead, making this a

two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE CPFSLT REG, 1

NLESS :

LESS :

Before Instruction

PC = Address (HERE)

W= ?

After Instruction

If REG < W;

PC = Address (LESS)

If REG ≥ W;

PC = Address (NLESS)

PIC18F2585/2680/4585/4680

DAW Decimal Adjust W Register

Syntax: DAW

Operands: None

Operation: If [W<3:0> >9] or [DC = 1] then

(W<3:0>) + 6 → W<3:0>;

else

(W<3:0>) → W<3:0>;

If [W<7:4> >9] or [C = 1] then

(W<7:4>) + 6 → W<7:4>;

C = 1;

else

(W<7:4>) → W<7:4>;

Status Affected: C

Encoding: 0000 0000 0000 0111

Description: DAW adjusts the eight-bit value in W,

resulting from the earlier addition of two

variables (each in packed BCD format)

and produces a correct packed BCD

result.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example 1:

DAW

Before Instruction

W=A5h

C=0

DC = 0

After Instruction

W = 05h

C=1

DC = 0

Example 2:

Before Instruction

W=CEh

C=0

DC = 0

After Instruction

W = 34h

C=1

DC = 0

DECF Decrement f

Syntax: DECF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) – 1 → dest

Status Affected: C, DC, N, OV, Z

Encoding: 0000 01da ffff ffff

Description: Decrement register ‘f’. If ‘d’ is ‘0’, the

result is stored in W. If ‘d’ is ‘1’, the

result is stored back in register ‘f’

(default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: DECF CNT, 1, 0

Before Instruction

CNT = 01h

Z=0

After Instruction

CNT = 00h

Z=1

PIC18F2585/2680/4585/4680

DECFSZ Decrement f, Skip if 0

Syntax: DECFSZ f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) – 1 → dest,

skip if result = 0

Status Affected: None

Encoding: 0010 11da ffff ffff

Description: The contents of register ‘f’ are

decremented. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If the result is ‘0’, the next instruction

which is already fetched is discarded

and a NOP is executed instead, making

it a two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE DECFSZ CNT, 1, 1

GOTO LOOP

CONTINUE

Before Instruction

PC = Address (HERE)

After Instruction

CNT = CNT – 1

If CNT = 0;

PC = Address (CONTINUE)

If CNT ≠0;

PC = Address (HERE + 2)

DCFSNZ Decrement f, Skip if not 0

Syntax: DCFSNZ f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) – 1 → dest,

skip if result ≠ 0

Status Affected: None

Encoding: 0100 11da ffff ffff

Description: The contents of register ‘f’ are

decremented. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If the result is not ‘0’, the next

instruction which is already fetched is

discarded and a NOP is executed

instead, making it a two-cycle

instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE DCFSNZ TEMP, 1, 0

ZERO :

NZERO :

Before Instruction

TEMP = ?

After Instruction

TEMP = TEMP – 1,

If TEMP = 0;

PC = Address (ZERO)

If TEMP ≠0;

PC = Address (NZERO)

PIC18F2585/2680/4585/4680

GOTO Unconditional Branch

Syntax: GOTO k

Operands: 0 ≤ k ≤ 1048575

Operation: k → PC<20:1>

Status Affected: None

Encoding:

1st word (k<7:0>)

2nd word(k<19:8>)

1110

1111

k19kkk

k7kkk

kkkk

kkkk0

kkkk8

Description: GOTO allows an unconditional branch

anywhere within entire

2-Mbyte memory range. The 20-bit

value ‘k’ is loaded into PC<20:1>.

GOTO is always a two-cycle

instruction.

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal

‘k’<7:0>,

operation

Read literal

‘k’<19:8>,

Write to PC

operation

Example: GOTO THERE

After Instruction

PC = Address (THERE)

INCF Increment f

Syntax: INCF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) + 1 → dest

Status Affected: C, DC, N, OV, Z

Encoding: 0010 10da ffff ffff

Description: The contents of register ‘f’ are

incremented. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: INCF CNT, 1, 0

Before Instruction

CNT = FFh

Z=0

C=?

DC = ?

After Instruction

CNT = 00h

Z=1

C=1

DC = 1

PIC18F2585/2680/4585/4680

INCFSZ Increment f, Skip if 0

Syntax: INCFSZ f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) + 1 → dest,

skip if result = 0

Status Affected: None

Encoding: 0011 11da ffff ffff

Description: The contents of register ‘f’ are

incremented. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If the result is ‘0’, the next instruction

which is already fetched is discarded

and a NOP is executed instead, making

it a two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE INCFSZ CNT, 1, 0

NZERO :

ZERO :

Before Instruction

PC = Address (HERE)

After Instruction

CNT = CNT + 1

If CNT = 0;

PC = Address (ZERO)

If CNT ≠0;

PC = Address (NZERO)

INFSNZ Increment f, Skip if Not 0

Syntax: INFSNZ f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) + 1 → dest,

skip if result ≠ 0

Status Affected: None

Encoding: 0100 10da ffff ffff

Description: The contents of register ‘f’ are

incremented. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If the result is not ‘0’, the next

instruction which is already fetched is

discarded and a NOP is executed

instead, making it a two-cycle

instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE INFSNZ REG, 1, 0

ZERO

NZERO

Before Instruction

PC = Address (HERE)

After Instruction

REG = REG + 1

If REG ≠0;

PC = Address (NZERO)

If REG = 0;

PC = Address (ZERO)

PIC18F2585/2680/4585/4680

IORLW Inclusive OR Literal with W

Syntax: IORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .OR. k → W

Status Affected: N, Z

Encoding: 0000 1001 kkkk kkkk

Description: The contents of W are ORed with the

eight-bit literal ‘k’. The result is placed

in W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to W

Example: IORLW 35h

Before Instruction

W=9Ah

After Instruction

W=BFh

IORWF Inclusive OR W with f

Syntax: IORWF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) .OR. (f) → dest

Status Affected: N, Z

Encoding: 0001 00da ffff ffff

Description: Inclusive OR W with register ‘f’. If ‘d’ is

‘0’, the result is placed in W. If ‘d’ is ‘1’,

the result is placed back in register ‘f’

(default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: IORWF RESULT, 0, 1

Before Instruction

RESULT = 13h

W = 91h

After Instruction

RESULT = 13h

W = 93h

PIC18F2585/2680/4585/4680

LFSR Load FSR

Syntax: LFSR f, k

Operands: 0 ≤ f ≤ 2

0 ≤ k ≤ 4095

Operation: k → FSRf

Status Affected: None

Encoding: 1110

1111

1110

0000

00ff

k7kkk

k11kkk

kkkk

Description: The 12-bit literal ‘k’ is loaded into the

file select register pointed to by ‘f’.

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal

‘k’ MSB

Process

Data

Write

literal ‘k’

MSB to

FSRfH

Decode Read literal

‘k’ LSB

Process

Data

Write literal

‘k’ to FSRfL

Example: LFSR 2, 3ABh

After Instruction

FSR2H = 03h

FSR2L = ABh

MOVF Move f

Syntax: MOVF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: f → dest

Status Affected: N, Z

Encoding: 0101 00da ffff ffff

Description: The contents of register ‘f’ are moved to

a destination dependent upon the

status of ‘d’. If ‘d’ is ‘0’, the result is

placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

Location ‘f’ can be anywhere in the

256-byte bank.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write W

Example: MOVF REG, 0, 0

Before Instruction

REG = 22h

W=FFh

After Instruction

REG = 22h

W = 22h

PIC18F2585/2680/4585/4680

MOVFF Move f to f

Syntax: MOVFF fs,fd

Operands: 0 ≤ fs ≤ 4095

0 ≤ fd ≤ 4095

Operation: (fs) → fd

Status Affected: None

Encoding:

1st word (source)

2nd word (destin.)

1100

1111

ffff

ffffs

ffffd

Description: The contents of source register ‘fs’ are

moved to destination register ‘fd’.

Location of source ‘fs’ can be anywhere

in the 4096-byte data space (000h to

FFFh) and location of destination ‘fd’

can also be anywhere from 000h to

FFFh.

Either source or destination can be W

(a useful special situation).

MOVFF is particularly useful for

transferring a data memory location to a

peripheral register (such as the transmit

buffer or an I/O port).

The MOVFF instruction cannot use the

PCL, TOSU, TOSH or TOSL as the

destination register

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

(src)

Process

Data

operation

Decode No

operation

No dummy

read

operation

Write

(dest)

Example: MOVFF REG1, REG2

Before Instruction

REG1 = 33h

REG2 = 11h

After Instruction

REG1 = 33h

REG2 = 33h

MOVLB Move Literal to Low Nibble in BSR

Syntax: MOVLW k

Operands: 0 ≤ k ≤ 255

Operation: k → BSR

Status Affected: None

Encoding: 0000 0001 kkkk kkkk

Description: The eight-bit literal ‘k’ is loaded into the

Bank Select Register (BSR). The value

of BSR<7:4> always remains ‘0’,

regardless of the value of k7:k4.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write literal

‘k’ to BSR

Example: MOVLB 5

Before Instruction

BSR Register = 02h

After Instruction

BSR Register = 05h

PIC18F2585/2680/4585/4680

MOVLW Move Literal to W

Syntax: MOVLW k

Operands: 0 ≤ k ≤ 255

Operation: k → W

Status Affected: None

Encoding: 0000 1110 kkkk kkkk

Description: The eight-bit literal ‘k’ is loaded into W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to W

Example: MOVLW 5Ah

After Instruction

W=5Ah

MOVWF Move W to f

Syntax: MOVWF f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: (W) → f

Status Affected: None

Encoding: 0110 111a ffff ffff

Description: Move data from W to register ‘f’.

Location ‘f’ can be anywhere in the

256-byte bank.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: MOVWF REG, 0

Before Instruction

W=4Fh

REG = FFh

After Instruction

W=4Fh

REG = 4Fh

PIC18F2585/2680/4585/4680

MULLW Multiply Literal with W

Syntax: MULLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) x k → PRODH:PRODL

Status Affected: None

Encoding: 0000 1101 kkkk kkkk

Description: An unsigned multiplication is carried

out between the contents of W and the

8-bit literal ‘k’. The 16-bit result is

placed in the PRODH:PRODL register

pair. PRODH contains the high byte.

W is unchanged.

None of the Status flags are affected.

Note that neither overflow nor carry is

possible in this operation. A zero result

is possible but not detected.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write

registers

PRODH:

PRODL

Example: MULLW 0C4h

Before Instruction

W=E2h

PRODH = ?

PRODL = ?

After Instruction

W=E2h

PRODH = ADh

PRODL = 08h

MULWF Multiply W with f

Syntax: MULWF f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: (W) x (f) → PRODH:PRODL

Status Affected: None

Encoding: 0000 001a ffff ffff

Description: An unsigned multiplication is carried

out between the contents of W and the

result is stored in the PRODH:PRODL

high byte. Both W and ‘f’ are

unchanged.

None of the Status flags are affected.

Note that neither overflow nor carry is

possible in this operation. A zero

result is possible but not detected.

If ‘a’ is ‘0’, the Access Bank is

selected. If ‘a’ is ‘1’, the BSR is used

to select the GPR bank (default).

If ‘a’ is ‘0’ and the extended

instruction set is enabled, this

instruction operates in Indexed Literal

Offset Addressing mode whenever

f ≤ 95 (5Fh). See Section 25.2.3

“Byte-Oriented and Bit-Oriented

Instructions in Indexed Literal Offset

Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

registers

PRODH:

PRODL

Example: MULWF REG, 1

Before Instruction

W=C4h

REG = B5h

PRODH = ?

PRODL = ?

After Instruction

W=C4h

REG = B5h

PRODH = 8Ah

PRODL = 94h

PIC18F2585/2680/4585/4680

NEGF Negate f

Syntax: NEGF f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: ( f ) + 1 → f

Status Affected: N, OV, C, DC, Z

Encoding: 0110 110a ffff ffff

Description: Location ‘f’ is negated using two’s

complement. The result is placed in the

data memory location ‘f’.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: NEGF REG, 1

Before Instruction

REG = 0011 1010 [3Ah]

After Instruction

REG = 1100 0110 [C6h]

NOP No Operation

Syntax: NOP

Operands: None

Operation: No operation

Status Affected: None

Encoding: 0000

1111

0000

xxxx

0000

xxxx

0000

xxxx

Description: No operation.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

Example:

None.

PIC18F2585/2680/4585/4680

POP Pop Top of Return Stack

Syntax: POP

Operands: None

Operation: (TOS) → bit bucket

Status Affected: None

Encoding: 0000 0000 0000 0110

Description: The TOS value is pulled off the return

stack and is discarded. The TOS value

then becomes the previous value that

was pushed onto the return stack.

This instruction is provided to enable

the user to properly manage the return

stack to incorporate a software stack.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

POP TOS

value

operation

Example: POP

GOTO NEW

Before Instruction

TOS = 0031A2h

Stack (1 level down) = 014332h

After Instruction

TOS = 014332h

PC = NEW

PUSH Push Top of Return Stack

Syntax: PUSH

Operands: None

Operation: (PC + 2) → TOS

Status Affected: None

Encoding: 0000 0000 0000 0101

Description: The PC + 2 is pushed onto the top of

the return stack. The previous TOS

value is pushed down on the stack.

This instruction allows implementing a

software stack by modifying TOS and

then pushing it onto the return stack.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode PUSH

PC + 2 onto

return stack

operation

Example: PUSH

Before Instruction

TOS = 345Ah

PC = 0124h

After Instruction

PC = 0126h

TOS = 0126h

Stack (1 level down) = 345Ah

PIC18F2585/2680/4585/4680

RCALL Relative Call

Syntax: RCALL n

Operands: -1024 ≤ n ≤ 1023

Operation: (PC) + 2 → TOS,

(PC) + 2 + 2n → PC

Status Affected: None

Encoding: 1101 1nnn nnnn nnnn

Description: Subroutine call with a jump up to 1K

from the current location. First, return

address (PC + 2) is pushed onto the

stack. Then, add the 2’s complement

number ‘2n’ to the PC. Since the PC will

have incremented to fetch the next

instruction, the new address will be

PC + 2 + 2n. This instruction is a

two-cycle instruction.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read literal ‘n’

Push PC to

stack

Process

Data

Write to PC

operation

Example: HERE RCALL Jump

Before Instruction

PC = Address (HERE)

After Instruction

PC = Address (Jump)

TOS = Address (HERE + 2)

RESET Reset

Syntax: RESET

Operands: None

Operation: Reset all registers and flags that are

affected by a MCLR Reset.

Status Affected: All

Encoding: 0000 0000 1111 1111

Description: This instruction provides a way to

execute a MCLR Reset in software.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Start

Reset

operation

Example: RESET

After Instruction

Registers = Reset Value

Flags* = Reset Value

PIC18F2585/2680/4585/4680

RETFIE Return from Interrupt

Syntax: RETFIE {s}

Operands: s ∈ [0,1]

Operation: (TOS) → PC,

1 → GIE/GIEH or PEIE/GIEL,

if s = 1

(WS) → W,

(STATUSS) → STATUS,

(BSRS) → BSR,

PCLATU, PCLATH are unchanged.

Status Affected: GIE/GIEH, PEIE/GIEL.

Encoding: 0000 0000 0001 000s

Description: Return from Interrupt. Stack is popped

and Top-of-Stack (TOS) is loaded into

the PC. Interrupts are enabled by

setting either the high or low priority

global interrupt enable bit. If ‘s’ = 1, the

contents of the shadow registers, WS,

STATUSS and BSRS, are loaded into

their corresponding registers, W,

STATUS and BSR. If ‘s’ = 0, no update

of these registers occurs (default).

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

POP PC

from stack

Set GIEH or

GIEL

operation

Example: RETFIE 1

After Interrupt

PC = TOS

W=WS

BSR = BSRS

STATUS = STATUSS

GIE/GIEH, PEIE/GIEL = 1

RETLW Return Literal to W

Syntax: RETLW k

Operands: 0 ≤ k ≤ 255

Operation: k → W,

(TOS) → PC,

PCLATU, PCLATH are unchanged

Status Affected: None

Encoding: 0000 1100 kkkk kkkk

Description: W is loaded with the eight-bit literal ‘k’.

The program counter is loaded from the

top of the stack (the return address).

The high address latch (PCLATH)

remains unchanged.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

POP PC

from stack,

Write to W

operation

Example:

CALL TABLE ; W contains table

; offset value

; W now has

; table value

TABLE

ADDWF PCL ; W = offset

RETLW k0 ; Begin table

RETLW k1 ;

RETLW kn ; End of table

Before Instruction

W = 07h

After Instruction

W = value of kn

PIC18F2585/2680/4585/4680

RETURN Return from Subroutine

Syntax: RETURN {s}

Operands: s ∈ [0,1]

Operation: (TOS) → PC,

if s = 1

(WS) → W,

(STATUSS) → STATUS,

(BSRS) → BSR,

PCLATU, PCLATH are unchanged

Status Affected: None

Encoding: 0000 0000 0001 001s

Description: Return from subroutine. The stack is

popped and the top of the stack (TOS)

is loaded into the program counter. If

‘s’= 1, the contents of the shadow

registers, WS, STATUSS and BSRS,

are loaded into their corresponding

registers, W, STATUS and BSR. If

‘s’ = 0, no update of these registers

occurs (default).

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

Process

Data

POP PC

from stack

operation

Example: RETURN

After Interrupt

PC = TOS

RLCF Rotate Left f through Carry

Syntax: RLCF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f<n>) → dest<n + 1>,

(f<7>) → C,

Status Affected: C, N, Z

Encoding: 0011 01da ffff ffff

Description: The contents of register ‘f’ are rotated

one bit to the left through the Carry

flag. If ‘d’ is ‘0’, the result is placed in

W. If ‘d’ is ‘1’, the result is stored back

in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is

selected. If ‘a’ is ‘1’, the BSR is used to

select the GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction

operates in Indexed Literal Offset

Addressing mode whenever

f ≤ 95 (5Fh). See Section 25.2.3

“Byte-Oriented and Bit-Oriented

Instructions in Indexed Literal Offset

Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: RLCF REG, 0, 0

Before Instruction

REG = 1110 0110

C=0

After Instruction

REG = 1110 0110

W=1100 1100

C=1

Cregister f

PIC18F2585/2680/4585/4680

RLNCF Rotate Left f (No Carry)

Syntax: RLNCF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f<n>) → dest<n + 1>,

(f<7>) → dest<0>

Status Affected: N, Z

Encoding: 0100 01da ffff ffff

Description: The contents of register ‘f’ are rotated

one bit to the left. If ‘d’ is ‘0’, the result

is placed in W. If ‘d’ is ‘1’, the result is

stored back in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: RLNCF REG, 1, 0

Before Instruction

REG = 1010 1011

After Instruction

REG = 0101 0111

RRCF Rotate Right f through Carry

Syntax: RRCF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f<n>) → dest<n – 1>,

(f<0>) → C,

Status Affected: C, N, Z

Encoding: 0011 00da ffff ffff

Description: The contents of register ‘f’ are rotated

one bit to the right through the Carry

flag. If ‘d’ is ‘0’, the result is placed in W.

If ‘d’ is ‘1’, the result is placed back in

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: RRCF REG, 0, 0

Before Instruction

REG = 1110 0110

C=0

After Instruction

REG = 1110 0110

W=0111 0011

C=0

Cregister f

PIC18F2585/2680/4585/4680

RRNCF Rotate Right f (No Carry)

Syntax: RRNCF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f<n>) → dest<n – 1>,

(f<0>) → dest<7>

Status Affected: N, Z

Encoding: 0100 00da ffff ffff

Description: The contents of register ‘f’ are rotated

one bit to the right. If ‘d’ is ‘0’, the result

is placed in W. If ‘d’ is ‘1’, the result is

placed back in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank will be

selected, overriding the BSR value. If ‘a’

is ‘1’, then the bank will be selected as

per the BSR value (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example 1: RRNCF REG, 1, 0

Before Instruction

REG = 1101 0111

After Instruction

REG = 1110 1011

Example 2: RRNCF REG, 0, 0

Before Instruction

W=?

REG = 1101 0111

After Instruction

W=1110 1011

REG = 1101 0111

SETF Set f

Syntax: SETF f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: FFh → f

Status Affected: None

Encoding: 0110 100a ffff ffff

Description: The contents of the specified register

are set to FFh.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write

Example: SETF REG,1

Before Instruction

REG = 5Ah

After Instruction

REG = FFh

PIC18F2585/2680/4585/4680

SLEEP Enter Sleep mode

Syntax: SLEEP

Operands: None

Operation: 00h → WDT,

0 → WDT postscaler,

1 → TO,

0 → PD

Status Affected: TO, PD

Encoding: 0000 0000 0000 0011

Description: The Power-Down status bit (PD) is

cleared. The Time-out status bit (TO)

is set. Watchdog Timer and its

postscaler are cleared.

The processor is put into Sleep mode

with the oscillator stopped.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

Process

Data

Go to

Sleep

Example: SLEEP

Before Instruction

TO =?

PD =?

After Instruction

TO =1 †

PD =0

† If WDT causes wake-up, this bit is cleared.

SUBFWB Subtract f from W with Borrow

Syntax: SUBFWB f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) – (f) – (C) → dest

Status Affected: N, OV, C, DC, Z

Encoding: 0101 01da ffff ffff

Description: Subtract register ‘f’ and Carry flag

(borrow) from W (2’s complement

method). If ‘d’ is ‘0’, the result is stored

in W. If ‘d’ is ‘1’, the result is stored in

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example 1: SUBFWB REG, 1, 0

Before Instruction

REG = 3

W=2

C=1

After Instruction

REG = FF

W=2

C=0

Z=0

N = 1 ; result is negative

Example 2: SUBFWB REG, 0, 0

Before Instruction

REG = 2

W=5

C=1

After Instruction

REG = 2

W=3

C=1

Z=0

N = 0 ; result is positive

Example 3: SUBFWB REG, 1, 0

Before Instruction

REG = 1

W=2

C=0

After Instruction

REG = 0

W=2

C=1

Z = 1 ; result is zero

N=0

PIC18F2585/2680/4585/4680

SUBLW Subtract W from Literal

Syntax: SUBLW k

Operands: 0 ≤ k ≤ 255

Operation: k – (W) → W

Status Affected: N, OV, C, DC, Z

Encoding: 0000 1000 kkkk kkkk

Description: W is subtracted from the eight-bit

literal ‘k’. The result is placed in W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to W

Example 1: SUBLW 02h

Before Instruction

W = 01h

C=?

After Instruction

W = 01h

C = 1 ; result is positive

Z=0

N=0

Example 2: SUBLW 02h

Before Instruction

W = 02h

C=?

After Instruction

W = 00h

C = 1 ; result is zero

Z=1

N=0

Example 3: SUBLW 02h

Before Instruction

W = 03h

C=?

After Instruction

W = FFh; (2’s complement)

C = 0 ; result is negative

Z=0

N=1

SUBWF Subtract W from f

Syntax: SUBWF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) – (W) → dest

Status Affected: N, OV, C, DC, Z

Encoding: 0101 11da ffff ffff

Description: Subtract W from register ‘f’ (2’s

complement method). If ‘d’ is ‘0’, the

result is stored in W. If ‘d’ is ‘1’, the

result is stored back in register ‘f’

(default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example 1: SUBWF REG, 1, 0

Before Instruction

REG = 3

W=2

C=?

After Instruction

REG = 1

W=2

C = 1 ; result is positive

Z=0

N=0

Example 2: SUBWF REG, 0, 0

Before Instruction

REG = 2

W=2

C=?

After Instruction

REG = 2

W=0

C = 1 ; result is zero

Z=1

N=0

Example 3: SUBWF REG, 1, 0

Before Instruction

REG = 1

W=2

C=?

After Instruction

REG = FFh ;(2’s complement)

W=2

C = 0 ; result is negative

Z=0

N=1

PIC18F2585/2680/4585/4680

SUBWFB Subtract W from f with Borrow

Syntax: SUBWFB f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f) – (W) – (C) → dest

Status Affected: N, OV, C, DC, Z

Encoding: 0101 10da ffff ffff

Description: Subtract W and the Carry flag (borrow)

from register ‘f’ (2’s complement

method). If ‘d’ is ‘0’, the result is stored

in W. If ‘d’ is ‘1’, the result is stored back

in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example 1: SUBWFB REG, 1, 0

Before Instruction

REG = 19h (0001 1001)

W=0Dh (0000 1101)

C=1

After Instruction

REG = 0Ch (0000 1011)

W=0Dh (0000 1101)

C=1

Z=0

N = 0 ; result is positive

Example 2: SUBWFB REG, 0, 0

Before Instruction

REG = 1Bh (0001 1011)

W=1Ah (0001 1010)

C=0

After Instruction

REG = 1Bh (0001 1011)

W = 00h

C=1

Z = 1 ; result is zero

N=0

Example 3: SUBWFB REG, 1, 0

Before Instruction

REG = 03h (0000 0011)

W=0Eh (0000 1101)

C=1

After Instruction

REG = F5h (1111 0100)

; [2’s comp]

W=0Eh (0000 1101)

C=0

Z=0

N = 1 ; result is negative

SWAPF Swap f

Syntax: SWAPF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (f<3:0>) → dest<7:4>,

(f<7:4>) → dest<3:0>

Status Affected: None

Encoding: 0011 10da ffff ffff

Description: The upper and lower nibbles of register

‘f’ are exchanged. If ‘d’ is ‘0’, the result

is placed in W. If ‘d’ is ‘1’, the result is

placed in register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: SWAPF REG, 1, 0

Before Instruction

REG = 53h

After Instruction

REG = 35h

PIC18F2585/2680/4585/4680

TBLRD Table Read

Syntax: TBLRD ( *; *+; *-; +*)

Operands: None

Operation: if TBLRD *,

(Prog Mem (TBLPTR)) → TABLAT;

TBLPTR – No Change;

if TBLRD *+,

(Prog Mem (TBLPTR)) → TABLAT;

(TBLPTR) + 1 → TBLPTR;

if TBLRD *-,

(Prog Mem (TBLPTR)) → TABLAT;

(TBLPTR) – 1 → TBLPTR;

if TBLRD +*,

(TBLPTR) + 1 → TBLPTR;

(Prog Mem (TBLPTR)) → TABLAT;

Status Affected: None

Encoding: 0000 0000 0000 10nn

nn=0 *

=1 *+

=2 *-

=3 +*

Description: This instruction is used to read the contents

of Program Memory (P.M.). To address the

program memory, a pointer, called Table

Pointer (TBLPTR), is used.

The TBLPTR (a 21-bit pointer) points to

each byte in the program memory. TBLPTR

has a 2-Mbyte address range.

TBLPTR[0] = 0: Least Significant Byte of

Program Memory Word

TBLPTR[0] = 1: Most Significant Byte of

Program Memory Word

The TBLRD instruction can modify the value

of TBLPTR as follows:

• no change

• post-increment

• post-decrement

• pre-increment

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

No operation

(Read Program

Memory)

operation

No operation

(Write

TABLAT)

TBLRD Table Read (Continued)

Example 1: TBLRD *+ ;

Before Instruction

TABLAT = 55h

TBLPTR = 00A356h

MEMORY(00A356h) = 34h

After Instruction

TABLAT = 34h

TBLPTR = 00A357h

Example 2: TBLRD +* ;

Before Instruction

TABLAT = 0AAh

TBLPTR = 01A357h

MEMORY(01A357h) = 12h

MEMORY(01A358h) = 34h

After Instruction

TABLAT = 34h

TBLPTR = 01A358h

PIC18F2585/2680/4585/4680

TBLWT Table Write

Syntax: TBLWT ( *; *+; *-; +*)

Operands: None

Operation: if TBLWT*,

(TABLAT) → Holding Register;

TBLPTR – No Change;

if TBLWT*+,

(TABLAT) → Holding Register;

(TBLPTR) + 1 → TBLPTR;

if TBLWT*-,

(TABLAT) → Holding Register;

(TBLPTR) – 1 → TBLPTR;

if TBLWT+*,

(TBLPTR) + 1 → TBLPTR;

(TABLAT) → Holding Register;

Status Affected: None

Encoding: 0000 0000 0000 11nn

nn=0 *

=1 *+

=2 *-

=3 +*

Description: This instruction uses the 3 LSBs of the

TBLPTR to determine which of the

8 holding registers the TABLAT is written to.

The holding registers are used to program

the contents of Program Memory (P.M.).

(Refer to Section 6.0 “Flash Program

Memory” for additional details on

programming Flash memory.)

The TBLPTR (a 21-bit pointer) points to

each byte in the program memory. TBLPTR

has a 2-MBtye address range. The LSb of

the TBLPTR selects which byte of the

program memory location to access.

TBLPTR[0] = 0: Least Significant Byte

of Program Memory

Word

TBLPTR[0] = 1: Most Significant Byte of

Program Memory Word

The TBLWT instruction can modify the

value of TBLPTR as follows:

• no change

• post-increment

• post-decrement

• pre-increment

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode No

operation

(Read

TABLAT)

operation

(Write to

Holding

TBLWT Table Write (Continued)

Example 1: TBLWT *+;

Before Instruction

TABLAT = 55h

TBLPTR = 00A356h

HOLDING REGISTER

(00A356h) = FFh

After Instructions (table write completion)

TABLAT = 55h

TBLPTR = 00A357h

HOLDING REGISTER

(00A356h) = 55h

Example 2: TBLWT +*;

Before Instruction

TABLAT = 34h

TBLPTR = 01389Ah

HOLDING REGISTER

(01389Ah) = FFh

HOLDING REGISTER

(01389Bh) = FFh

After Instruction (table write completion)

TABLAT = 34h

TBLPTR = 01389Bh

HOLDING REGISTER

(01389Ah) = FFh

HOLDING REGISTER

(01389Bh) = 34h

PIC18F2585/2680/4585/4680

TSTFSZ Test f, Skip if 0

Syntax: TSTFSZ f {,a}

Operands: 0 ≤ f ≤ 255

a ∈ [0,1]

Operation: skip if f = 0

Status Affected: None

Encoding: 0110 011a ffff ffff

Description: If ‘f’ = 0, the next instruction fetched

during the current instruction execution

is discarded and a NOP is executed,

making this a two-cycle instruction.

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1(2)

Note: 3 cycles if skip and followed

by a 2-word instruction.

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

operation

If skip:

Q1 Q2 Q3 Q4

operation

If skip and followed by 2-word instruction:

Q1 Q2 Q3 Q4

operation

Example: HERE TSTFSZ CNT, 1

NZERO :

ZERO :

Before Instruction

PC = Address (HERE)

After Instruction

If CNT = 00h,

PC = Address (ZERO)

If CNT ≠00h,

PC = Address (NZERO)

XORLW Exclusive OR Literal with W

Syntax: XORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .XOR. k → W

Status Affected: N, Z

Encoding: 0000 1010 kkkk kkkk

Description: The contents of W are XORed with

the 8-bit literal ‘k’. The result is placed

in W.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to W

Example: XORLW 0AFh

Before Instruction

W=B5h

After Instruction

W=1Ah

PIC18F2585/2680/4585/4680

XORWF Exclusive OR W with f

Syntax: XORWF f {,d {,a}}

Operands: 0 ≤ f ≤ 255

d ∈ [0,1]

a ∈ [0,1]

Operation: (W) .XOR. (f) → dest

Status Affected: N, Z

Encoding: 0001 10da ffff ffff

Description: Exclusive OR the contents of W with

in W. If ‘d’ is ‘1’, the result is stored back

in the register ‘f’ (default).

If ‘a’ is ‘0’, the Access Bank is selected.

If ‘a’ is ‘1’, the BSR is used to select the

GPR bank (default).

If ‘a’ is ‘0’ and the extended instruction

set is enabled, this instruction operates

in Indexed Literal Offset Addressing

mode whenever f ≤ 95 (5Fh). See

Section 25.2.3 “Byte-Oriented and

Bit-Oriented Instructions in Indexed

Literal Offset Mode” for details.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: XORWF REG, 1, 0

Before Instruction

REG = AFh

W=B5h

After Instruction

REG = 1Ah

W=B5h

PIC18F2585/2680/4585/4680

25.2 Extended Instruction Set

In addition to the standard 75 instructions of the PIC18

instruction set, PIC18F2585/2680/4585/4680 devices

also provide an optional extension to the core CPU

functionality. The added features include eight

additional instructions that augment indirect and

indexed addressing operations and the implementation

of Indexed Literal Offset Addressing mode for many of

the standard PIC18 instructions.

The additional features are disabled by default. To

enable them, users must set the XINST Configuration

bit.

The instructions in the extended set can all be

classified as literal operations, which either manipulate

the File Select Registers or use them for indexed

addressing. Two of the instructions, ADDFSR and

SUBFSR, each have an additional special instantiation

for using FSR2. These versions (ADDULNK and

SUBULNK) allow for automatic return after execution.

The extended instructions are specifically implemented

to optimize re-entrant program code (that is, code that

is recursive or that uses a software stack) written in

high-level languages, particularly C. Among other

things, they allow users working in high-level

languages to perform certain operations on data

structures more efficiently. These include:

• dynamic allocation and de-allocation of software

stack space when entering and leaving

subroutines

• function pointer invocation

• software stack pointer manipulation

• manipulation of variables located in a software

stack

A summary of the instructions in the extended instruc-

tion set is provided in Table 25-3. Detailed descriptions

are provided in Section 25.2.2 “Extended Instruction

Set”. The opcode field descriptions in Table 25-1 apply

to both the standard and extended PIC18 instruction

sets.

25.2.1 EXTENDED INSTRUCTION SYNTAX

Most of the extended instructions use indexed

arguments, using one of the File Select Registers and

some offset to specify a source or destination register.

When an argument for an instruction serves as part of

indexed addressing, it is enclosed in square brackets

(“[ ]”). This is done to indicate that the argument is used

as an index or offset. MPASM™ Assembler will flag an

error if it determines that an index or offset value is not

bracketed.

When the extended instruction set is enabled, brackets

are also used to indicate index arguments in bit-

oriented and byte-oriented instructions. This is in

addition to other changes in their syntax. For more

details, see Section 25.2.3.1 “Extended Instruction

Syntax with Standard PIC18 Commands”.

TABLE 25-3: EXTENSIONS TO THE PIC18 INSTRUCTION SET

Note: The instruction set extension and the

Indexed Literal Offset Addressing mode

were designed for optimizing applications

written in C; the user may likely never use

these instructions directly in assembler.

The syntax for these commands is pro-

vided as a reference for users who may be

reviewing code that has been generated

by a compiler.

Note: In the past, square brackets have been

used to denote optional arguments in the

PIC18 and earlier instruction sets. In this

text and going forward, optional arguments

are denoted by braces (“{ }”).

Mnemonic,

Operands Description Cycles

16-Bit Instruction Word Status

Affected

MSb LSb

ADDFSR

ADDULNK

CALLW

MOVSF

MOVSS

PUSHL

SUBFSR

SUBULNK

f, k

zs, fd

zs, zd

f, k

Add literal to FSR

Add literal to FSR2 and return

Call subroutine using WREG

Move zs (source) to 1st word

fd (destination) 2nd word

Move zs (source) to 1st word

zd (destination) 2nd word

Store literal at FSR2,

decrement FSR2

Subtract literal from FSR

Subtract literal from FSR2 and

return

1110

0000

1110

1111

1110

1111

1110

1000

0000

1011

ffff

1011

xxxx

1010

1001

ffkk

11kk

0001

0zzz

ffff

1zzz

xzzz

kkkk

ffkk

11kk

kkkk

0100

zzzz

ffff

zzzz

kkkk

None

PIC18F2585/2680/4585/4680

25.2.2 EXTENDED INSTRUCTION SET

ADDFSR Add Literal to FSR

Syntax: ADDFSR f, k

Operands: 0 ≤ k ≤ 63

f ∈ [ 0, 1, 2 ]

Operation: FSR(f) + k → FSR(f)

Status Affected: None

Encoding: 1110 1000 ffkk kkkk

Description: The 6-bit literal ‘k’ is added to the

contents of the FSR specified by ‘f’.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to

FSR

Example: ADDFSR 2, 23h

Before Instruction

FSR2 = 03FFh

After Instruction

FSR2 = 0422h

ADDULNK Add Literal to FSR2 and Return

Syntax: ADDULNK k

Operands: 0 ≤ k ≤ 63

Operation: FSR2 + k → FSR2,

PC = (TOS)

Status Affected: None

Encoding: 1110 1000 11kk kkkk

Description: The 6-bit literal ‘k’ is added to the

contents of FSR2. A RETURN is then

executed by loading the PC with the

TOS.

The instruction takes two cycles to

execute; a NOP is performed during the

second cycle.

This may be thought of as a special case

of the ADDFSR instruction, where f = 3

(binary ‘11’); it operates only on FSR2.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

literal ‘k’

Process

Data

Write to

FSR

Operation

Example: ADDULNK 23h

Before Instruction

FSR2 = 03FFh

PC = 0100h

TOS = 02AFh

After Instruction

FSR2 = 0422h

PC = 02AFh

TOS = TOS – 1

Note: All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in

symbolic addressing. If a label is used, the instruction syntax then becomes: {label} instruction argument(s).

PIC18F2585/2680/4585/4680

CALLW Subroutine Call Using WREG

Syntax: CALLW

Operands: None

Operation: (PC + 2) → TOS,

(W) → PCL,

(PCLATH) → PCH,

(PCLATU) → PCU

Status Affected: None

Encoding: 0000 0000 0001 0100

Description First, the return address (PC + 2) is

pushed onto the return stack. Next, the

contents of W are written to PCL; the

existing value is discarded. Then, the

contents of PCLATH and PCLATU are

latched into PCH and PCU,

respectively. The second cycle is

executed as a NOP instruction while the

new next instruction is fetched.

Unlike CALL, there is no option to

update W, STATUS or BSR.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

WREG

Push PC to

stack

operation

Example: HERE CALLW

Before Instruction

PC = address (HERE)

PCLATH = 10h

PCLATU = 00h

W = 06h

After Instruction

PC = 001006h

TOS = address (HERE + 2)

PCLATH = 10h

PCLATU = 00h

W = 06h

MOVSF Move Indexed to f

Syntax: MOVSF [zs], fd

Operands: 0 ≤ zs ≤ 127

0 ≤ fd ≤ 4095

Operation: ((FSR2) + zs) → fd

Status Affected: None

Encoding:

1st word (source)

2nd word (destin.)

1110

1111

1011

ffff

0zzz

ffff

zzzzs

ffffd

Description: The contents of the source register are

moved to destination register ‘fd’. The

actual address of the source register is

determined by adding the 7-bit literal

offset ‘zs’ in the first word to the value of

FSR2. The address of the destination

‘fd’ in the second word. Both addresses

can be anywhere in the 4096-byte data

space (000h to FFFh).

The MOVSF instruction cannot use the

PCL, TOSU, TOSH or TOSL as the

destination register.

If the resultant source address points to

an indirect addressing register, the

value returned will be 00h.

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Determine

source addr

Determine

source addr

Read

source reg

Decode No

operation

No dummy

read

operation

Write

(dest)

Example: MOVSF [05h], REG2

Before Instruction

FSR2 = 80h

Contents

of 85h = 33h

REG2 = 11h

After Instruction

FSR2 = 80h

Contents

of 85h = 33h

REG2 = 33h

PIC18F2585/2680/4585/4680

MOVSS Move Indexed to Indexed

Syntax: MOVSS [zs], [zd]

Operands: 0 ≤ zs ≤ 127

0 ≤ zd ≤ 127

Operation: ((FSR2) + zs) → ((FSR2) + zd)

Status Affected: None

Encoding:

1st word (source)

2nd word (dest.)

1110

1111

1011

xxxx

1zzz

xzzz

zzzzs

zzzzd

Description The contents of the source register are

moved to the destination register. The

addresses of the source and destination

registers are determined by adding the

7-bit literal offsets ‘zs’ or ‘zd’,

respectively, to the value of FSR2. Both

registers can be located anywhere in

the 4096-byte data memory space

(000h to FFFh).

The MOVSS instruction cannot use the

PCL, TOSU, TOSH or TOSL as the

destination register.

If the resultant source address points to

an indirect addressing register, the

value returned will be 00h. If the

resultant destination address points to

an indirect addressing register, the

instruction will execute as a NOP.

Words: 2

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Determine

source addr

Determine

source addr

Read

source reg

Decode Determine

dest addr

Determine

dest addr

Write

to dest reg

Example: MOVSS [05h], [06h]

Before Instruction

FSR2 = 80h

Contents

of 85h = 33h

Contents

of 86h = 11h

After Instruction

FSR2 = 80h

Contents

of 85h = 33h

Contents

of 86h = 33h

PUSHL Store Literal at FSR2, Decrement FSR2

Syntax: PUSHL k

Operands: 0 ≤ k ≤ 255

Operation: k → (FSR2),

FSR2 – 1 → FSR2

Status Affected: None

Encoding: 1111 1010 kkkk kkkk

Description: The 8-bit literal ‘k’ is written to the data

memory address specified by FSR2. FSR2 is

decremented by 1 after the operation.

This instruction allows users to push values

onto a software stack.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read ‘k’ Process

data

Write to

destination

Example: PUSHL 08h

Before Instruction

FSR2H:FSR2L = 01ECh

Memory (01ECh) = 00h

After Instruction

FSR2H:FSR2L = 01EBh

Memory (01ECh) = 08h

PIC18F2585/2680/4585/4680

SUBFSR Subtract Literal from FSR

Syntax: SUBFSR f, k

Operands: 0 ≤ k ≤ 63

f ∈ [ 0, 1, 2 ]

Operation: FSRf – k → FSRf

Status Affected: None

Encoding: 1110 1001 ffkk kkkk

Description: The 6-bit literal ‘k’ is subtracted from

the contents of the FSR specified

by ‘f’.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: SUBFSR 2, 23h

Before Instruction

FSR2 = 03FFh

After Instruction

FSR2 = 03DCh

SUBULNK

Subtract Literal from FSR2 and Return

Syntax: SUBULNK k

Operands: 0 ≤ k ≤ 63

Operation: FSR2 – k → FSR2

(TOS) → PC

Status Affected:

None

Encoding: 1110 1001 11kk kkkk

Description: The 6-bit literal ‘k’ is subtracted from the

contents of the FSR2. A RETURN is then

executed by loading the PC with the TOS.

The instruction takes two cycles to execute;

a NOP is performed during the second cycle.

This may be thought of as a special case of

the SUBFSR instruction, where f = 3 (binary

‘11’); it operates only on FSR2.

Words: 1

Cycles: 2

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Operation

Example: SUBULNK 23h

Before Instruction

FSR2 = 03FFh

PC = 0100h

After Instruction

FSR2 = 03DCh

PC = (TOS)

PIC18F2585/2680/4585/4680

25.2.3 BYTE-ORIENTED AND

BIT-ORIENTED INSTRUCTIONS IN

INDEXED LITERAL OFFSET MODE

In addition to eight new commands in the extended set,

enabling the extended instruction set also enables

Indexed Literal Offset Addressing mode (Section 5.6.1

“Indexed Addressing with Literal Offset”). This has

a significant impact on the way that many commands of

the standard PIC18 instruction set are interpreted.

When the extended set is disabled, addresses embed-

ded in opcodes are treated as literal memory locations:

either as a location in the Access Bank (a = 0), or in a

GPR bank designated by the BSR (a = 1). When the

extended instruction set is enabled and a = 0, however,

a file register argument of 5Fh or less is interpreted as

an offset from the pointer value in FSR2 and not as a

literal address. For practical purposes, this means that

all instructions that use the Access RAM bit as an

argument – that is, all bit-oriented and byte-oriented

instructions, or almost half of the core PIC18 instructions

– may behave differently when the extended instruction

set is enabled.

When the content of FSR2 is 00h, the boundaries of the

Access RAM are essentially remapped to their original

values. This may be useful in creating backward

compatible code. If this technique is used, it may be

necessary to save the value of FSR2 and restore it

when moving back and forth between ‘C’ and assembly

routines in order to preserve the Stack Pointer. Users

must also keep in mind the syntax requirements of the

extended instruction set (see Section 25.2.3.1

“Extended Instruction Syntax with Standard PIC18

Commands”).

Although the Indexed Literal Offset Addressing mode

can be very useful for dynamic stack and pointer

manipulation, it can also be very annoying if a simple

arithmetic operation is carried out on the wrong

programming must keep in mind that, when the

extended instruction set is enabled, register addresses

of 5Fh or less are used for Indexed Literal Offset

Addressing.

Representative examples of typical byte-oriented and

bit-oriented instructions in the Indexed Literal Offset

Addressing mode are provided on the following page to

show how execution is affected. The operand

conditions shown in the examples are applicable to all

instructions of these types.

25.2.3.1 Extended Instruction Syntax with

Standard PIC18 Commands

When the extended instruction set is enabled, the file

bit-oriented commands, is replaced with the literal off-

set value, ‘k’. As already noted, this occurs only when

‘f’ is less than or equal to 5Fh. When an offset value is

used, it must be indicated by square brackets (“[ ]”). As

with the extended instructions, the use of brackets indi-

cates to the compiler that the value is to be interpreted

as an index or an offset. Omitting the brackets, or using

a value greater than 5Fh within brackets, will generate

an error in the MPASM™ Assembler.

If the index argument is properly bracketed for Indexed

Literal Offset Addressing, the Access RAM argument is

never specified; it will automatically be assumed to be

‘0’. This is in contrast to standard operation (extended

instruction set disabled) when ‘a’ is set on the basis of

the target address. Declaring the Access RAM bit in

this mode will also generate an error in the MPASM

Assembler.

The destination argument, ‘d’, functions as before.

In the latest versions of the MPASM Assembler,

language support for the extended instruction set must

be explicitly invoked. This is done with either the

command line option, /y, or the PE directive in the

source listing.

25.2.4 CONSIDERATIONS WHEN

ENABLING THE EXTENDED

INSTRUCTION SET

It is important to note that the extensions to the instruc-

tion set may not be beneficial to all users. In particular,

users who are not writing code that uses a software

stack may not benefit from using the extensions to the

instruction set.

Additionally, the Indexed Literal Offset Addressing

mode may create issues with legacy applications

written to the PIC18 assembler. This is because

instructions in the legacy code may attempt to address

registers in the Access Bank below 5Fh. Since these

addresses are interpreted as literal offsets to FSR2

when the instruction set extension is enabled, the

application may read or write to the wrong data

addresses.

When porting an application to the PIC18F2585/2680/

4585/4680, it is very important to consider the type of

code. A large, re-entrant application that is written in ‘C’

and would benefit from efficient compilation will do well

when using the instruction set extensions. Legacy

applications that heavily use the Access Bank will most

likely not benefit from using the extended instruction

set.

Note: Enabling the PIC18 instruction set

extension may cause legacy applications

to behave erratically or fail entirely.

PIC18F2585/2680/4585/4680

ADDWF ADD W to Indexed

(Indexed Literal Offset mode)

Syntax: ADDWF [k] {,d}

Operands: 0 ≤ k ≤ 95

d ∈ [0,1]

a = 0

Operation: (W) + ((FSR2) + k) → dest

Status Affected: N, OV, C, DC, Z

Encoding: 0010 01d0 kkkk kkkk

Description: The contents of W are added to the contents

of the register indicated by FSR2, offset by the

value ‘k’.

If ‘d’ is ‘0’, the result is stored in W. If ‘d’ is ‘1’,

the result is stored back in register ‘f’ (default).

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read ‘k’ Process

Data

Write to

destination

Example: ADDWF [OFST] ,0

Before Instruction

W = 17h

OFST = 2Ch

FSR2 = 0A00h

Contents

of 0A2Ch = 20h

After Instruction

W = 37h

Contents

of 0A2Ch = 20h

BSF Bit Set Indexed

(Indexed Literal Offset mode)

Syntax: BSF [k], b

Operands: 0 ≤ f ≤ 95

0 ≤ b ≤ 7

a = 0

Operation: 1 → ((FSR2 + k))

Status Affected: None

Encoding: 1000 bbb0 kkkk kkkk

Description: Bit ‘b’ of the register indicated by FSR2,

offset by the value ‘k’, is set.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read

Process

Data

Write to

destination

Example: BSF [FLAG_OFST], 7

Before Instruction

FLAG_OFST = 0Ah

FSR2 = 0A00h

Contents

of 0A0Ah = 55h

After Instruction

Contents

of 0A0Ah = D5h

SETF Set Indexed

(Indexed Literal Offset mode)

Syntax: SETF [k]

Operands: 0 ≤ k ≤ 95

Operation: FFh → ((FSR2) + k)

Status Affected: None

Encoding: 0110 1000 kkkk kkkk

Description: The contents of the register indicated by

FSR2, offset by ‘k’, are set to FFh.

Words: 1

Cycles: 1

Q Cycle Activity:

Q1 Q2 Q3 Q4

Decode Read ‘k’ Process

Data

Write

Example: SETF [OFST]

Before Instruction

OFST = 2Ch

FSR2 = 0A00h

Contents

of 0A2Ch = 00h

After Instruction

Contents

of 0A2Ch = FFh

PIC18F2585/2680/4585/4680

25.2.5 SPECIAL CONSIDERATIONS WITH

MICROCHIP MPLAB® IDE TOOLS

The latest versions of Microchip’s software tools have

been designed to fully support the extended instruction

set of the PIC18F2585/2680/4585/4680 family of

devices. This includes the MPLAB C18 C compiler,

MPASM assembly language and MPLAB Integrated

Development Environment (IDE).

When selecting a target device for software develop-

ment, MPLAB IDE will automatically set default

Configuration bits for that device. The default setting for

the XINST Configuration bit is ‘0’, disabling the extended

instruction set and Indexed Literal Offset Addressing

mode. For proper execution of applications developed to

take advantage of the extended instruction set, XINST

must be set during programming.

To develop software for the extended instruction set,

the user must enable support for the instructions and

the Indexed Addressing mode in their language tool(s).

Depending on the environment being used, this may be

done in several ways:

• A menu option, or dialog box within the

environment, that allows the user to configure the

language tool and its settings for the project

• A command line option

• A directive in the source code

These options vary between different compilers,

assemblers and development environments. Users are

encouraged to review the documentation accompany-

ing their development systems for the appropriate

information.

PIC18F2585/2680/4585/4680

26.0 DEVELOPMENT SUPPORT

The PIC® microcontrollers are supported with a full

range of hardware and software development tools:

• Integrated Development Environment

- MPLAB® IDE Software

• Assemblers/Compilers/Linkers

- MPASMTM Assembler

- MPLAB C18 and MPLAB C30 C Compilers

-MPLINK

TM Object Linker/

MPLIBTM Object Librarian

- MPLAB ASM30 Assembler/Linker/Library

• Simulators

- MPLAB SIM Software Simulator

•Emulators

- MPLAB ICE 2000 In-Circuit Emulator

- MPLAB REAL ICE™ In-Circuit Emulator

• In-Circuit Debugger

- MPLAB ICD 2

• Device Programmers

- PICSTART® Plus Development Programmer

- MPLAB PM3 Device Programmer

- PICkit™ 2 Development Programmer

• Low-Cost Demonstration and Development

Boards and Evaluation Kits

26.1 MPLAB Integrated Development

Environment Software

The MPLAB IDE software brings an ease of software

development previously unseen in the 8/16-bit micro-

controller market. The MPLAB IDE is a Windows®

operating system-based application that contains:

• A single graphical interface to all debugging tools

- Simulator

- Programmer (sold separately)

- Emulator (sold separately)

- In-Circuit Debugger (sold separately)

• A full-featured editor with color-coded context

• A multiple project manager

• Customizable data windows with direct edit of

contents

• High-level source code debugging

• Visual device initializer for easy register

initialization

• Mouse over variable inspection

• Drag and drop variables from source to watch

windows

• Extensive on-line help

• Integration of select third party tools, such as

HI-TECH Software C Compilers and IAR

C Compilers

The MPLAB IDE allows you to:

• Edit your source files (either assembly or C)

• One touch assemble (or compile) and download

to PIC MCU emulator and simulator tools

(automatically updates all project information)

• Debug using:

- Source files (assembly or C)

- Mixed assembly and C

- Machine code

MPLAB IDE supports multiple debugging tools in a

single development paradigm, from the cost-effective

simulators, through low-cost in-circuit debuggers, to

full-featured emulators. This eliminates the learning

curve when upgrading to tools with increased flexibility

and power.

PIC18F2585/2680/4585/4680

26.2 MPASM Assembler

The MPASM Assembler is a full-featured, universal

macro assembler for all PIC MCUs.

The MPASM Assembler generates relocatable object

files for the MPLINK Object Linker, Intel® standard HEX

files, MAP files to detail memory usage and symbol

reference, absolute LST files that contain source lines

and generated machine code and COFF files for

debugging.

The MPASM Assembler features include:

• Integration into MPLAB IDE projects

• User-defined macros to streamline

assembly code

• Conditional assembly for multi-purpose

source files

• Directives that allow complete control over the

assembly process

26.3 MPLAB C18 and MPLAB C30

C Compilers

The MPLAB C18 and MPLAB C30 Code Development

Systems are complete ANSI C compilers for

Microchip’s PIC18 and PIC24 families of microcontrol-

lers and the dsPIC30 and dsPIC33 family of digital sig-

nal controllers. These compilers provide powerful

integration capabilities, superior code optimization and

ease of use not found with other compilers.

For easy source level debugging, the compilers provide

symbol information that is optimized to the MPLAB IDE

debugger.

26.4 MPLINK Object Linker/

MPLIB Object Librarian

The MPLINK Object Linker combines relocatable

objects created by the MPASM Assembler and the

MPLAB C18 C Compiler. It can link relocatable objects

from precompiled libraries, using directives from a

linker script.

The MPLIB Object Librarian manages the creation and

modification of library files of precompiled code. When

a routine from a library is called from a source file, only

the modules that contain that routine will be linked in

with the application. This allows large libraries to be

used efficiently in many different applications.

The object linker/library features include:

• Efficient linking of single libraries instead of many

smaller files

• Enhanced code maintainability by grouping

related modules together

• Flexible creation of libraries with easy module

listing, replacement, deletion and extraction

26.5 MPLAB ASM30 Assembler, Linker

and Librarian

MPLAB ASM30 Assembler produces relocatable

machine code from symbolic assembly language for

dsPIC30F devices. MPLAB C30 C Compiler uses the

assembler to produce its object file. The assembler

generates relocatable object files that can then be

archived or linked with other relocatable object files and

archives to create an executable file. Notable features

of the assembler include:

• Support for the entire dsPIC30F instruction set

• Support for fixed-point and floating-point data

• Command line interface

• Rich directive set

• Flexible macro language

• MPLAB IDE compatibility

26.6 MPLAB SIM Software Simulator

The MPLAB SIM Software Simulator allows code

development in a PC-hosted environment by simulat-

ing the PIC MCUs and dsPIC® DSCs on an instruction

level. On any given instruction, the data areas can be

examined or modified and stimuli can be applied from

a comprehensive stimulus controller. Registers can be

logged to files for further run-time analysis. The trace

buffer and logic analyzer display extend the power of

the simulator to record and track program execution,

actions on I/O, most peripherals and internal registers.

The MPLAB SIM Software Simulator fully supports

symbolic debugging using the MPLAB C18 and

MPLAB C30 C Compilers, and the MPASM and

MPLAB ASM30 Assemblers. The software simulator

offers the flexibility to develop and debug code outside

of the hardware laboratory environment, making it an

excellent, economical software development tool.

PIC18F2585/2680/4585/4680

26.7 MPLAB ICE 2000

High-Performance

In-Circuit Emulator

The MPLAB ICE 2000 In-Circuit Emulator is intended

to provide the product development engineer with a

complete microcontroller design tool set for PIC

microcontrollers. Software control of the MPLAB ICE

2000 In-Circuit Emulator is advanced by the MPLAB

Integrated Development Environment, which allows

editing, building, downloading and source debugging

from a single environment.

The MPLAB ICE 2000 is a full-featured emulator

system with enhanced trace, trigger and data monitor-

ing features. Interchangeable processor modules allow

the system to be easily reconfigured for emulation of

different processors. The architecture of the MPLAB

ICE 2000 In-Circuit Emulator allows expansion to

support new PIC microcontrollers.

The MPLAB ICE 2000 In-Circuit Emulator system has

been designed as a real-time emulation system with

advanced features that are typically found on more

expensive development tools. The PC platform and

Microsoft® Windows® 32-bit operating system were

chosen to best make these features available in a

simple, unified application.

26.8 MPLAB REAL ICE In-Circuit

Emulator System

MPLAB REAL ICE In-Circuit Emulator System is

Microchip’s next generation high-speed emulator for

Microchip Flash DSC® and MCU devices. It debugs and

programs PIC® and dsPIC® Flash microcontrollers with

the easy-to-use, powerful graphical user interface of the

MPLAB Integrated Development Environment (IDE),

included with each kit.

The MPLAB REAL ICE probe is connected to the design

engineer’s PC using a high-speed USB 2.0 interface and

is connected to the target with either a connector

compatible with the popular MPLAB ICD 2 system

(RJ11) or with the new high speed, noise tolerant, low-

voltage differential signal (LVDS) interconnection

(CAT5).

MPLAB REAL ICE is field upgradeable through future

firmware downloads in MPLAB IDE. In upcoming

releases of MPLAB IDE, new devices will be supported,

and new features will be added, such as software break-

points and assembly code trace. MPLAB REAL ICE

offers significant advantages over competitive emulators

including low-cost, full-speed emulation, real-time

variable watches, trace analysis, complex breakpoints, a

ruggedized probe interface and long (up to three meters)

interconnection cables.

26.9 MPLAB ICD 2 In-Circuit Debugger

Microchip’s In-Circuit Debugger, MPLAB ICD 2, is a

powerful, low-cost, run-time development tool,

connecting to the host PC via an RS-232 or high-speed

USB interface. This tool is based on the Flash PIC

MCUs and can be used to develop for these and other

PIC MCUs and dsPIC DSCs. The MPLAB ICD 2 utilizes

the in-circuit debugging capability built into the Flash

devices. This feature, along with Microchip’s In-Circuit

Serial ProgrammingTM (ICSPTM) protocol, offers cost-

effective, in-circuit Flash debugging from the graphical

user interface of the MPLAB Integrated Development

Environment. This enables a designer to develop and

debug source code by setting breakpoints, single step-

ping and watching variables, and CPU status and

peripheral registers. Running at full speed enables

testing hardware and applications in real time. MPLAB

ICD 2 also serves as a development programmer for

selected PIC devices.

26.10 MPLAB PM3 Device Programmer

The MPLAB PM3 Device Programmer is a universal,

CE compliant device programmer with programmable

voltage verification at VDDMIN and VDDMAX for

maximum reliability. It features a large LCD display

(128 x 64) for menus and error messages and a modu-

lar, detachable socket assembly to support various

package types. The ICSP™ cable assembly is included

as a standard item. In Stand-Alone mode, the MPLAB

PM3 Device Programmer can read, verify and program

PIC devices without a PC connection. It can also set

code protection in this mode. The MPLAB PM3

connects to the host PC via an RS-232 or USB cable.

The MPLAB PM3 has high-speed communications and

optimized algorithms for quick programming of large

memory devices and incorporates an SD/MMC card for

file storage and secure data applications.

PIC18F2585/2680/4585/4680

26.11 PICSTART Plus Development

Programmer

The PICSTART Plus Development Programmer is an

easy-to-use, low-cost, prototype programmer. It

connects to the PC via a COM (RS-232) port. MPLAB

Integrated Development Environment software makes

using the programmer simple and efficient. The

PICSTART Plus Development Programmer supports

most PIC devices in DIP packages up to 40 pins.

Larger pin count devices, such as the PIC16C92X and

PIC17C76X, may be supported with an adapter socket.

The PICSTART Plus Development Programmer is CE

compliant.

26.12 PICkit 2 Development Programmer

The PICkit™ 2 Development Programmer is a low-cost

programmer and selected Flash device debugger with

an easy-to-use interface for programming many of

Microchip’s baseline, mid-range and PIC18F families of

Flash memory microcontrollers. The PICkit 2 Starter Kit

includes a prototyping development board, twelve

sequential lessons, software and HI-TECH’s PICC™

Lite C compiler, and is designed to help get up to speed

quickly using PIC® microcontrollers. The kit provides

everything needed to program, evaluate and develop

applications using Microchip’s powerful, mid-range

Flash memory family of microcontrollers.

26.13 Demonstration, Development and

Evaluation Boards

A wide variety of demonstration, development and

evaluation boards for various PIC MCUs and dsPIC

DSCs allows quick application development on fully func-

tional systems. Most boards include prototyping areas for

adding custom circuitry and provide application firmware

and source code for examination and modification.

The boards support a variety of features, including LEDs,

temperature sensors, switches, speakers, RS-232

interfaces, LCD displays, potentiometers and additional

EEPROM memory.

The demonstration and development boards can be

used in teaching environments, for prototyping custom

circuits and for learning about various microcontroller

applications.

In addition to the PICDEM™ and dsPICDEM™ demon-

stration/development board series of circuits, Microchip

has a line of evaluation kits and demonstration software

for analog filter design, KEELOQ® security ICs, CAN,

IrDA®, PowerSmart® battery management, SEEVAL®

evaluation system, Sigma-Delta ADC, flow rate

sensing, plus many more.

Check the Microchip web page (www.microchip.com)

and the latest

“Product Selector Guide”

(DS00148) for

the complete list of demonstration, development and

evaluation kits.

PIC18F2585/2680/4585/4680

27.0 ELECTRICAL CHARACTERISTICS

Absolute Maximum Ratings (†)

Ambient temperature under bias.............................................................................................................-40°C to +125°C

Storage temperature .............................................................................................................................. -65°C to +150°C

Voltage on any pin with respect to VSS (except VDD and MCLR) ................................................... -0.3V to (VDD + 0.3V)

Voltage on VDD with respect to VSS ......................................................................................................... -0.3V to +7.5V

Voltage on MCLR with respect to VSS (Note 2) ......................................................................................... 0V to +13.25V

Total power dissipation (Note 1) ...............................................................................................................................1.0W

Maximum current out of VSS pin ...........................................................................................................................300 mA

Maximum current into VDD pin ..............................................................................................................................250 mA

Input clamp current, IIK (VI < 0 or VI > VDD)...................................................................................................................... ±20 mA

Output clamp current, IOK (VO < 0 or VO > VDD).............................................................................................................. ±20 mA

Maximum output current sunk by any I/O pin..........................................................................................................25 mA

Maximum output current sourced by any I/O pin ....................................................................................................25 mA

Maximum current sunk by all ports .......................................................................................................................200 mA

Maximum current sourced by all ports ..................................................................................................................200 mA

Note 1: Power dissipation is calculated as follows:

Pdis = VDD x {IDD – ∑ IOH} + ∑ {(VDD – VOH) x IOH} + ∑(VOL x IOL)

2: Voltage spikes below VSS at the MCLR/VPP pin, inducing currents greater than 80 mA, may cause latch-up.

Thus, a series resistor of 50-100Ω should be used when applying a “low” level to the MCLR/VPP/RE3 pin,

rather than pulling this pin directly to VSS.

† NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the

device. This is a stress rating only and functional operation of the device at those or any other conditions above those

indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for

extended periods may affect device reliability.

PIC18F2585/2680/4585/4680

FIGURE 27-1: PIC18F2585/2680/4585/4680 VOLTAGE-FREQUENCY GRAPH

(INDUSTRIAL AND EXTENDED)

FIGURE 27-2: PIC18LF2585/2680/4585/4680 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL)

Frequency

Voltage

6.0V

5.5V

4.0V

2.0V

40 MHz

3.5V

3.0V

2.5V

4.2V

25 MHz

4.5V

5.0V

Industrial and

Extended devices

Industrial devices

only

PIC18FX585/X680

Frequency

Voltage

6.0V

5.5V

4.5V

4.0V

2.0V

40 MHz

5.0V

3.5V

3.0V

2.5V

PIC18LFX585/X680

FMAX = (16.36 MHz/V) (VDDAPPMIN – 2.0V) + 4 MHz

Note: VDDAPPMIN is the minimum voltage of the PIC® device in the application.

4 MHz

4.2V

PIC18F2585/2680/4585/4680

27.1 DC Characteristics: Supply Voltage

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Symbol Characteristic Min Typ Max Units Conditions

VDD Supply Voltage

D001 PIC18LFX585/X680 2.0 — 5.5 V

PIC18FX585/X680 4.2 —5.5 V

D002 VDR RAM Data Retention

Voltage(1)

1.5 — — V

D003 VPOR VDD Start Voltage

to ensure internal

Power-on Reset signal

— — 0.7 V See section on Power-on Reset for details

D004 SVDD VDD Rise Rate

to ensure internal

Power-on Reset signal

0.05 — — V/ms See section on Power-on Reset for details

VBOR Brown-out Reset Voltage

PIC18LFX585/X680

D005 BORV1:BORV0 = 11 2.00 2.05 2.16 V

BORV1:BORV0 = 10 2.65 2.79 2.93 V

All Devices

BORV1:BORV0 = 01 4.11 4.33 4.55 V

BORV1:BORV0 = 00 4.36 4.59 4.82 V

Legend: Shading of rows is to assist in readability of the table.

Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM data.

PIC18F2585/2680/4585/4680

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Power-down Current (IPD)(1)

PIC18LFX585/X680 0.25 0.95 μA -40°C

VDD = 2.0V,

(Sleep mode)

0.3 1.0 μA +25°C

3.0 6.0 μA +85°C

PIC18LFX585/X680 0.3 1.4 μA -40°C

VDD = 3.0V,

(Sleep mode)

0.35 2.0 μA +25°C

3.5 8.0 μA +85°C

All devices 0.5 1.9 μA -40°C

VDD = 5.0V,

(Sleep mode)

0.5 2.0 μA +25°C

6.0 15 μA +85°C

PIC18FX585/X680 10.00 120.00 μA+125°C

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18LFX585/X680 19.00 35.00 μA -40°C

VDD = 2.0V

FOSC = 31 kHz

(RC_RUN mode,

Internal oscillator source)

20.00 35.00 μA +25°C

22.00 35.00 μA +85°C

PIC18LFX585/X680 57.00 60.00 μA -40°C

VDD = 3.0V47.00 60.00 μA +25°C

42.00 60.00 μA +85°C

All devices 150.00 170.00 μA -40°C

VDD = 5.0V

120.00 170.00 μA +25°C

98.00 170.00 μA +85°C

PIC18FX585/X680 100.00 250.00 μA+125°C

PIC18LFX585/X680 0.53 1.10 μA -40°C

VDD = 2.0V

FOSC = 1 MHz

(RC_RUN mode,

Internal oscillator source)

0.55 1.10 mA +25°C

0.56 1.10 mA +85°C

PIC18LFX585/X680 0.94 1.20 mA -40°C

VDD = 3.0V0.90 1.20 mA +25°C

0.88 1.20 mA +85°C

All devices 1.80 2.30 mA -40°C

VDD = 5.0V

1.70 2.30 mA +25°C

1.60 2.30 mA +85°C

PIC18FX585/X680 2.60 3.60 mA +125°C

PIC18LFX585/X680 1.50 2.10 mA -40°C

VDD = 2.0V

FOSC = 4 MHz

(RC_RUN mode,

Internal oscillator source)

1.50 2.10 mA +25°C

1.50 2.10 mA +85°C

PIC18LFX585/X680 2.40 3.30 mA -40°C

VDD = 3.0V2.40 3.30 mA +25°C

2.40 3.30 mA +85°C

All devices 4.40 5.20 mA -40°C

VDD = 5.0V

4.40 5.20 mA +25°C

4.40 5.20 mA +85°C

PIC18FX585/X680 9.20 11.00 mA +125°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18LFX585/X680 6.10 8.40 μA -40°C

VDD = 2.0V

FOSC = 31 kHz

(RC_IDLE mode,

Internal oscillator source)

6.70 8.40 μA +25°C

7.40 22.0 μA +85°C

PIC18LFX585/X680 9.60 12.00 μA -40°C

VDD = 3.0V11.00 12.00 μA +25°C

12.00 33.00 μA +85°C

All devices 20.00 28.00 μA -40°C

VDD = 5.0V

22.00 28.00 μA +25°C

24.00 33.00 μA +85°C

PIC18FX585/X680 84.00 200.00 μA+125°C

PIC18LFX585/X680 300.00 390.00 μA -40°C

VDD = 2.0V

FOSC = 1 MHz

(RC_IDLE mode,

Internal oscillator source)

320.00 390.00 μA +25°C

330.00 390.00 μA +85°C

PIC18LFX585/X680 450.00 550.00 μA -40°C

VDD = 3.0V470.00 550.00 μA +25°C

490.00 550.00 μA +85°C

All devices 0.84 1.10 mA -40°C

VDD = 5.0V

0.88 1.10 mA +25°C

0.90 1.10 mA +85°C

PIC18FX585/X680 2.80 3.20 mA +125°C

PIC18LFX585/X680 0.76 1.10 mA -40°C

VDD = 2.0V

FOSC = 4 MHz

(RC_IDLE mode,

Internal oscillator source)

0.79 1.10 mA +25°C

0.81 1.10 mA +85°C

PIC18LFX585/X680 1.20 1.50 mA -40°C

VDD = 3.0V1.30 1.50 mA +25°C

1.30 1.50 mA +85°C

All devices 2.20 2.70 mA -40°C

VDD = 5.0V

2.30 2.70 mA +25°C

2.30 2.70 mA +85°C

PIC18FX585/X680 4.70 5.50 mA +125°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18LFX585/X680 410.00 550.00 μA -40°C

VDD = 2.0V

FOSC = 1 MHZ

(PRI_RUN,

EC oscillator)

420.00 550.00 μA +25°C

420.00 550.00 μA +85°C

PIC18LFX585/X680 0.87 0.88 mA -40°C

VDD = 3.0V0.77 0.88 mA +25°C

0.72 0.88 mA +85°C

All devices 1.90 3.00 mA -40°C

VDD = 5.0V

1.60 3.00 mA +25°C

1.50 3.00 mA +85°C

PIC18FX585/X680 1.50 3.30 mA +125°C

PIC18LFX585/X680 1.40 2.20 mA -40°C

VDD = 2.0V

FOSC = 4 MHz

(PRI_RUN,

EC oscillator)

1.40 2.20 mA +25°C

1.40 2.20 mA +85°C

PIC18LFX585/X680 2.30 3.30 mA -40°C

VDD = 3.0V2.30 3.30 mA +25°C

2.30 3.30 mA +85°C

All devices 4.50 6.60 mA -40°C

VDD = 5.0V

4.30 6.60 mA +25°C

4.30 6.60 mA +85°C

PIC18FX585/X680 5.00 7.70 mA +125°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18FX585/X680 15.00 23.00 mA +125°C VDD = 4.2V FOSC = 25 MHZ

(PRI_RUN, EC oscillator)

20.00 31.00 mA +125°C VDD = 5.0V

All devices 30.00 38.00 mA -40°C

VDD = 4.2V

FOSC = 40 MHZ

(PRI_RUN, EC oscillator)

31.00 38.00 mA +25°C

31.00 38.00 mA +85°C

All devices 37.00 44.00 mA -40°C

VDD = 5.0V38.00 44.00 mA +25°C

39.00 44.00 mA +85°C

All devices 7.50 16.00 mA -40°C

VDD = 4.2V FOSC = 4 MHZ

(PRI_RUN HS+PLL)

7.40 15.00 mA +25°C

7.30 14.00 mA +85°C

All devices 10.00 21.00 mA -40°C

VDD = 5.0V FOSC = 4 MHZ

(PRI_RUN HS+PLL)

10.00 20.00 mA +25°C

9.70 19.00 mA +85°C

All devices 17.00 35.00 mA -40°C

VDD = 4.2V FOSC = 10 MHZ

(PRI_RUN HS+PLL)

17.00 35.00 mA +25°C

17.00 35.00 mA +85°C

All devices 23.00 40.00 mA -40°C

VDD = 5.0V FOSC = 10 MHZ

(PRI_RUN HS+PLL)

23.00 40.00 mA +25°C

23.00 40.00 mA +85°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18LFX585/X680 160.000 220.00 μA -40°C

VDD = 2.0V

FOSC = 1 MHz

(PRI_IDLE mode,

EC oscillator)

160.000 220.00 μA +25°C

170.000 220.00 μA +85°C

PIC18LFX585/X680 250.00 330.00 μA -40°C

VDD = 3.0V250.00 330.00 μA +25°C

260.00 330.00 μA +85°C

All devices 460.00 550.00 μA -40°C

VDD = 5.0V

470.00 550.00 μA +25°C

480.00 550.00 μA +85°C

PIC18FX585/X680 0.79 0.92 mA +125°C

PIC18LFX585/X680 640.00 715.00 mA -40°C

VDD = 2.0V

FOSC = 4 MHz

(PRI_IDLE mode,

EC oscillator)

650.00 715.00 mA +25°C

660.00 715.00 mA +85°C

PIC18LFX585/X680 0.98 1.40 mA -40°C

VDD = 3.0V1.00 1.40 mA +25°C

1.00 1.40 mA +85°C

All devices 1.90 2.20 mA -40°C

VDD = 5.0V

1.90 2.20 mA +25°C

1.90 2.20 mA +85°C

PIC18FX585/X680 2.10 2.40 mA +125°C

PIC18FX585/X680 9.50 11.00 mA +125°C VDD = 4.2V FOSC = 25 MHz

(PRI_IDLE mode,

EC oscillator)

14.00 16.00 mA +125°C VDD = 5.0V

All devices 15.00 18.00 mA -40°C

VDD = 4.2V

FOSC = 40 MHz

(PRI_IDLE mode,

EC oscillator)

16.00 18.00 mA +25°C

16.00 18.00 mA +85°C

All devices 19.00 22.00 mA -40°C

VDD = 5.0V19.00 22.00 mA +25°C

19.00 22.00 mA +85°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Supply Current (IDD)(2,3)

PIC18LFX585/X680 22.00 44.00 μA -40°C

VDD = 2.0V

FOSC = 32 kHz(4)

(SEC_RUN mode,

Timer1 as clock)

20.00 44.00 μA +25°C

19.00 44.00 μA +85°C

PIC18LFX585/X680 56.00 71.00 μA -40°C

VDD = 3.0V45.00 71.00 μA +25°C

41.00 71.00 μA +85°C

All devices 138.00 162.00 μA -40°C

VDD = 5.0V106.00 162.00 μA +25°C

95.00 162.00 μA +85°C

PIC18LFX585/X680 6.20 24.00 μA -40°C

VDD = 2.0V

FOSC = 32 kHz(4)

(SEC_IDLE mode,

Timer1 as clock)

6.60 24.00 μA +25°C

7.70 24.00 μA +85°C

PIC18LFX585/X680 9.30 33.00 μA -40°C

VDD = 3.0V9.40 33.00 μA +25°C

11.00 33.00 μA +85°C

All devices 17.00 50.00 μA -40°C

VDD = 5.0V17.00 50.00 μA +25°C

20.00 50.00 μA +85°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

Module Differential Currents (ΔIWDT, ΔIBOR, ΔILVD, ΔIOSCB, ΔIAD)

D022

(ΔIWDT)

Watchdog Timer 1.00 7.60 μA -40°C

VDD = 2.0V1.30 8.00 μA +25°C

1.40 8.40 μA +85°C

1.90 11.40 μA -40°C

VDD = 3.0V2.20 12.00 μA +25°C

2.40 12.60 μA +85°C

5.50 14.30 μA -40°C

VDD = 5.0V

6.10 15.00 μA +25°C

6.50 15.80 μA +85°C

7.80 19.00 μA +125°C

D022A Brown-out Reset 26.00 50.00 μA-40°C to +85°CV

DD = 3.0V

(ΔIBOR) 27.00 52.00 μA-40°C to +85°CVDD = 5.0V

30.00 58.00 μA +125°C

D022B High/Low-Voltage Detect 16.00 42.00 μA-40°C to +85°CVDD = 2.0V

(ΔILVD) 17.00 44.00 μA-40°C to +85°CVDD = 3.0V

19.00 50.00 μA-40°C to +85°CVDD = 5.0V

19.00 50.00 μA +125°C

D025 Timer1 Oscillator 4.00 8.00 μA -40°C

VDD = 2.0V 32 kHz on Timer1(4)

(ΔIOSCB)4.008.00μA +25°C

4.00 8.00 μA +85°C

4.20 8.20 μA -40°C

VDD = 3.0V 32 kHz on Timer1(4)

4.20 8.20 μA +25°C

4.20 8.20 μA +85°C

5.00 10.00 μA -40°C

VDD = 5.0V 32 kHz on Timer1(4)

5.00 10.00 μA +25°C

5.00 10.00 μA +85°C

D026

(ΔIAD)

A/D Converter 1.0 2.0 μA-40°C to +85°CVDD = 2.0V

A/D on, not converting,

1.0 2.0 μA-40°C to +85°CVDD = 3.0V

1.0 2.0 μA-40°C to +85°CVDD = 5.0V

2.0 8.0 μA-40°C to +85°C

27.2 DC Characteristics: Power-Down and Supply Current

PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial, Extended)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

-40°C ≤ T

A ≤ +125°C for extended

Param

No. Device Typ Max Units Conditions

Legend: Shading of rows is to assist in readability of the table.

Note 1: The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the

part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current

disabled (such as WDT, Timer1 Oscillator, BOR, etc.).

2: The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading

and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on

the current consumption. The test conditions for all IDD measurements in active operation mode are:

OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD;

MCLR = VDD; WDT enabled/disabled as specified.

3: For RC oscillator configurations, current through REXT is not included. The current through the resistor can be estimated

by the formula Ir = VDD/2REXT (mA) with REXT in kΩ.

4: Standard low-cost 32 kHz crystals have an operating temperature range of -10°C to +70°C. Extended temperature

crystals are available at a much higher cost.

PIC18F2585/2680/4585/4680

27.3 DC Characteristics: PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Symbol Characteristic Min Max Units Conditions

VIL Input Low Voltage

I/O ports:

D030 with TTL buffer VSS 0.15 VDD VVDD < 4.5V

D030A — 0.8 V 4.5V ≤ VDD ≤ 5.5V

D031

D031A

D031B

with Schmitt Trigger buffer

RC3 and RC4

VSS

0.2 VDD

0.3 VDD

0.8

I2C™ enabled

SMBus enabled

D032 MCLR VSS 0.2 VDD V

D033 OSC1 VSS 0.3 VDD V HS, HSPLL modes

D033A OSC1 VSS 0.2 VDD V RC, EC modes(1)

D033B OSC1 VSS 0.3 V XT, LP modes

D034 T13CKI VSS 0.3 V

VIH Input High Voltage

I/O ports:

D040 with TTL buffer 0.25 VDD + 0.8V VDD VVDD < 4.5V

D040A 2.0 VDD V4.5V ≤ VDD ≤ 5.5V

D041

D041A

D041B

with Schmitt Trigger buffer

RC3 and RC4

0.8 VDD

0.7 VDD

2.1

VDD

I2C™ enabled

SMBus enabled

D042 MCLR 0.8 VDD VDD V

D043 OSC1 0.7 VDD VDD V HS, HSPLL modes

D043A OSC1 0.8 VDD VDD VEC mode

D043B OSC1 0.9 VDD VDD V RC mode(1)

D043C OSC1 1.6 VDD V XT, LP modes

D044 T13CKI 1.6 VDD V

IIL Input Leakage Current(2,3)

D060 I/O ports — ±1μAV

SS ≤ VPIN ≤ VDD,

Pin at high-impedance

D061 MCLR —±5μAVss ≤ VPIN ≤ VDD

D063 OSC1 — ±5μAVss ≤ VPIN ≤ VDD

IPU Weak Pull-up Current

D070 IPURB PORTB weak pull-up current 50 400 μAVDD = 5V, VPIN = VSS

Note 1: In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the

PIC® device be driven with an external clock while in RC mode.

2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified

levels represent normal operating conditions. Higher leakage current may be measured at different input

voltages.

3: Negative current is defined as current sourced by the pin.

4: Parameter is characterized but not tested.

PIC18F2585/2680/4585/4680

VOL Output Low Voltage

D080 I/O ports — 0.6 V IOL = 8.5 mA, VDD = 4.5V,

-40°C to +85°C

D083 OSC2/CLKO

(RC, RCIO, EC, ECIO modes)

—0.6VI

OL = 1.6 mA, VDD = 4.5V,

-40°C to +85°C

VOH Output High Voltage(3)

D090 I/O ports VDD – 0.7 — V IOH = -3.0 mA, VDD = 4.5V,

-40°C to +85°C

D092 OSC2/CLKO

(RC, RCIO, EC, ECIO modes)

VDD – 0.7 — V IOH = -1.3 mA, VDD = 4.5V,

-40°C to +85°C

Capacitive Loading Specs

on Output Pins

D100(4) COSC2 OSC2 pin —15 pF In XT, HS and LP modes

when external clock is

used to drive OSC1

D101 CIO All I/O pins and OSC2

(in RC mode)

— 50 pF To meet the AC Timing

Specifications

D102 CBSCL, SDA — 400 pF I2C™ Specification

27.3 DC Characteristics: PIC18F2585/2680/4585/4680 (Industrial)

PIC18LF2585/2680/4585/4680 (Industrial) (Continued)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Symbol Characteristic Min Max Units Conditions

Note 1: In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the

PIC® device be driven with an external clock while in RC mode.

2: The leakage current on the MCLR pin is strongly dependent on the applied voltage level. The specified

levels represent normal operating conditions. Higher leakage current may be measured at different input

voltages.

3: Negative current is defined as current sourced by the pin.

4: Parameter is characterized but not tested.

PIC18F2585/2680/4585/4680

TABLE 27-1: MEMORY PROGRAMMING REQUIREMENTS

DC Characteristics Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

Param

No. Sym Characteristic Min Typ† Max Units Conditions

Internal Program Memory

Programming Specifications(1)

D110 VPP Voltage on MCLR/VPP/RE3 pin 9.00 — 13.25 V (Note 3)

D113 IDDP Supply Current during

Programming

——10mA

Data EEPROM Memory

D120 EDByte Endurance 100K 1M — E/W -40°C to +85°C

D121 VDRW VDD for Read/Write VMIN — 5.5 V Using EECON to read/write

VMIN = Minimum operating

voltage

D122 TDEW Erase/Write Cycle Time — 4 — ms

D123 TRETD Characteristic Retention 40 — — Year Provided no other

specifications are violated

D124 TREF Number of Total Erase/Write

Cycles before Refresh(2)

1M 10M — E/W -40°C to +85°C

Program Flash Memory

D130 EPCell Endurance 10K 100K — E/W -40°C to +85°C

D131 VPR VDD for Read VMIN —5.5VVMIN = Minimum operating

voltage

D132 VIE VDD for Block Erase 4.5 — 5.5 V Using ICSP™ port

D132A VIW VDD for Externally Timed Erase

or Write

4.5 — 5.5 V Using ICSP port

D132B VPEW VDD for Self-timed Write VMIN —5.5VVMIN = Minimum operating

voltage

D133 TIE ICSP Block Erase Cycle Time — 4 — ms VDD > 4.5V

D133A TIW ICSP Erase or Write Cycle Time

(externally timed)

1——msVDD > 4.5V

D133A TIW Self-timed Write Cycle Time — 2 — ms

D134 TRETD Characteristic Retention 40 100 — Year Provided no other

specifications are violated

† Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

Note 1: These specifications are for programming the on-chip program memory through the use of table write

instructions.

2: Refer to Section 7.8 “Using the Data EEPROM” for a more detailed discussion on data EEPROM

endurance.

3: Required only if Single-Supply Programming is disabled.

PIC18F2585/2680/4585/4680

TABLE 27-2: COMPARATOR SPECIFICATIONS

TABLE 27-3: VOLTAGE REFERENCE SPECIFICATIONS

Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).

Param

No. Sym Characteristics Min Typ Max Units Comments

D300 VIOFF Input Offset Voltage — ± 5.0 ± 10 mV

D301 VICM Input Common Mode Voltage* 0 — VDD – 1.5 V

D302 CMRR Common Mode Rejection Ratio* 55 — — dB

300 TRESP Response Time(1)* — 150 400 ns PIC18FXXXX

300A — 150 600 ns PIC18LFXXXX,

VDD = 2.0V

301 TMC2OV Comparator Mode Change to

Output Valid*

—— 10μs

* These parameters are characterized but not tested.

Note 1: Response time measured with one comparator input at (VDD – 1.5)/2 while the other input transitions

from VSS to VDD.

Operating Conditions: 3.0V < VDD < 5.5V, -40°C < TA < +85°C (unless otherwise stated).

Param

No. Sym Characteristics Min Typ Max Units Comments

D310 VRES Resolution VDD/24 — VDD/32 LSb

D311 VRAA Absolute Accuracy —

—

1/4

1/2

LSb

Low Range (CVRR = 1)

High Range (CVRR = 0)

D312 VRUR Unit Resistor Value (R)* — 2k — Ω

310 TSET Settling Time(1)*— — 10 μs

* These parameters are characterized but not tested.

Note 1: Settling time measured while CVRR = 1 and CVR3:CVR0 transitions from ‘0000’ to ‘1111’.

PIC18F2585/2680/4585/4680

FIGURE 27-3: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS

TABLE 27-4: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS

VLVD

HLVDIF

VDD

(HLVDIF set by hardware)

(HLVDIF can be

cleared in software)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Symbol Characteristic Min Typ† Max Units Conditions

D420 HLVD Voltage on VDD

Transition High to Low

LVV = 0000 2.12 2.17 2.22 V

LVV = 0001 2.18 2.23 2.28 V

LVV = 0010 2.31 2.36 2.42 V

LVV = 0011 2.38 2.44 2.49 V

LVV = 0100 2.54 2.60 2.66 V

LVV = 0101 2.72 2.79 2.85 V

LVV = 0110 2.82 2.89 2.95 V

LVV = 0111 3.05 3.12 3.19 V

LVV = 1000 3.31 3.39 3.47 V

LVV = 1001 3.46 3.55 3.63 V

LVV = 1010 3.63 3.71 3.80 V

LVV = 1011 3.81 3.90 3.99 V

LVV = 1100 4.01 4.11 4.20 V

LVV = 1101 4.23 4.33 4.43 V

LVV = 1110 4.48 4.59 4.69 V

LVV = 1111 1.14 1.20 1.26 V

† Production tested at T

AMB = 25°C. Specifications over temperature limits ensured by characterization.

PIC18F2585/2680/4585/4680

27.4 AC (Timing) Characteristics

27.4.1 TIMING PARAMETER SYMBOLOGY

The timing parameter symbols have been created

using one of the following formats:

1. TppS2ppS 3. TCC:ST (I2C specifications only)

2. TppS 4. Ts (I2C specifications only)

F Frequency T Time

Lowercase letters (pp) and their meanings:

cc CCP1 osc OSC1

ck CLKO rd RD

cs CS rw RD or WR

di SDI sc SCK

do SDO ss SS

dt Data in t0 T0CKI

io I/O port t1 T13CKI

mc MCLR wr WR

Uppercase letters and their meanings:

F Fall P Period

HHigh RRise

I Invalid (High-impedance) V Valid

L Low Z High-impedance

I2C only

AA output access High High

BUF Bus free Low Low

TCC:ST (I2C specifications only)

HD Hold SU Setup

DAT DATA input hold STO Stop condition

STA Start condition

PIC18F2585/2680/4585/4680

27.4.2 TIMING CONDITIONS

The temperature and voltages specified in Table 27-5

apply to all timing specifications unless otherwise

noted. Figure 27-4 specifies the load conditions for the

timing specifications.

TABLE 27-5: TEMPERATURE AND VOLTAGE SPECIFICATIONS – AC

FIGURE 27-4: LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS

Note: Because of space limitations, the generic

terms “PIC18FXXXX” and “PIC18LFXXXX”

are used throughout this section to refer to

the PIC18F2585/2680/4585/4680 and

PIC18LF2585/2680/4585/4680 families of

devices specifically and only those devices.

AC CHARACTERISTICS

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Operating voltage VDD range as described in DC spec Section 27.1 and

Section 27.3. LF parts operate for industrial temperatures only.

VDD/2

VSS

RL= 464Ω

CL= 50 pF for all pins except OSC2/CLKO

and including D and E outputs as ports

Load Condition 1 Load Condition 2

PIC18F2585/2680/4585/4680

27.4.3 TIMING DIAGRAMS AND SPECIFICATIONS

FIGURE 27-5: EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL)

TABLE 27-6: EXTERNAL CLOCK TIMING REQUIREMENTS

OSC1

CLKO

Q4 Q1 Q2 Q3 Q4 Q1

3344

Param.

No. Symbol Characteristic Min Max Units Conditions

1A FOSC External CLKI Frequency(1) DC 1 MHz XT, RC Oscillator modes

DC 25 MHz HS Oscillator mode

DC 31.25 kHz LP Oscillator mode

DC 40 MHz EC Oscillator mode

Oscillator Frequency(1) DC 4 MHz RC Oscillator mode

0.1 4 MHz XT Oscillator mode

4 25 MHz HS Oscillator mode

4 10 MHz HSPLL Oscillator mode

5 200 kHz LP Oscillator mode

OSC External CLKI Period(1) 1000 — ns XT, RC Oscillator modes

40 — ns HS Oscillator mode

32 — μs LP Oscillator mode

25 — ns EC Oscillator mode

Oscillator Period(1) 250 — ns RC Oscillator mode

250 1 μs XT Oscillator mode

40 250 ns HS Oscillator mode

100 250 ns HSPLL Oscillator mode

5200μs LP Oscillator mode

CY Instruction Cycle Time(1) 100 — ns TCY = 4/FOSC

OSL,

TOSH

External Clock in (OSC1)

High or Low Time

30 — ns XT Oscillator mode

2.5 — μs LP Oscillator mode

10 — ns HS Oscillator mode

OSR,

TOSF

External Clock in (OSC1)

Rise or Fall Time

— 20 ns XT Oscillator mode

— 50 ns LP Oscillator mode

— 7.5 ns HS Oscillator mode

Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period for all configurations

except PLL. All specified values are based on characterization data for that particular oscillator type under

standard operating conditions with the device executing code. Exceeding these specified limits may result

in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested

to operate at “min.” values with an external clock applied to the OSC1/CLKI pin. When an external clock

input is used, the “max.” cycle time limit is “DC” (no clock) for all devices.

PIC18F2585/2680/4585/4680

TABLE 27-7: PLL CLOCK TIMING SPECIFICATIONS (VDD = 4.2V TO 5.5V)

TABLE 27-8: AC CHARACTERISTICS: INTERNAL RC ACCURACY

PIC18F2585/2680/4585/4680 (INDUSTRIAL)

PIC18LF2585/2680/4585/4680 (INDUSTRIAL)

Param

No. Sym Characteristic Min Typ† Max Units Conditions

F10 FOSC Oscillator Frequency Range 4 — 10 MHz HS mode only

F11 FSYS On-Chip VCO System Frequency 16 — 40 MHz HS mode only

F12 trc PLL Start-up Time (Lock Time) — — 2 ms

F13 ΔCLK CLKO Stability (Jitter) -2 — +2 %

† Data in “Typ” column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

PIC18LF2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ T

A ≤ +85°C for industrial

PIC18F2585/2680/4585/4680

(Industrial)

Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Device Min Typ Max Units Conditions

INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz(1)

PIC18LFX585/X680 -2 +/-1 2 % +25°C VDD = 2.7-3.3V

-5 — 5 % -10°C to +85°C VDD = 2.7-3.3V

-10 +/-1 10 % -40°C to +85°C VDD = 2.7-3.3V

PIC18FX585/X680 -2 +/-1 2 % +25°C VDD = 4.5-5.5V

-5 — 5 % -10°C to +85°C VDD = 4.5-5.5V

-10 +/-1 10 %-40°C to +85°C VDD = 4.5-5.5V

INTRC Accuracy @ Freq = 31 kHz(2)

PIC18LFX585/X680 26.562 — 35.938 kHz -40°C to +85°C VDD = 2.7-3.3V

PIC18FX585/X680 26.562 —35.938 kHz -40°C to +85°C VDD = 4.5-5.5V

Legend: Shading of rows is to assist in readability of the table.

Note 1: Frequency calibrated at 25°C. OSCTUNE register can be used to compensate for temperature drift.

2: INTRC frequency after calibration.

PIC18F2585/2680/4585/4680

FIGURE 27-6: CLKO AND I/O TIMING

TABLE 27-9: CLKO AND I/O TIMING REQUIREMENTS

Note: Refer to Figure 27-4 for load conditions.

OSC1

CLKO

I/O pin

(Input)

I/O pin

(Output)

Q4 Q1 Q2 Q3

20, 21

19 18

Old Value New Value

Param

No. Symbol Characteristic Min Typ Max Units Conditions

10 T

OSH2CKLOSC1 ↑ to CLKO ↓ — 75 200 ns (Note 1)

11 TOSH2CKHOSC1 ↑ to CLKO ↑ — 75 200 ns (Note 1)

12 TCKR CLKO Rise Time — 35 100 ns (Note 1)

13 TCKF CLKO Fall Time — 35 100 ns (Note 1)

14 TCKL2IOVCLKO ↓ to Port Out Valid — — 0.5 TCY + 20 ns (Note 1)

15 TIOV2CKH Port In Valid before CLKO ↑ 0.25 TCY + 25 — — ns (Note 1)

16 TCKH2IOI Port In Hold after CLKO ↑ 0——ns(Note 1)

17 TOSH2IOVOSC1 ↑ (Q1 cycle) to Port Out Valid — 50 150 ns

18 T

OSH2IOIOSC1 ↑ (Q2 cycle) to Port

Input Invalid (I/O in hold

time)

PIC18FXXXX 100 — — ns

18A PIC18LFXXXX 200 — — ns VDD = 2.0V

19 TIOV2OSH Port Input Valid to OSC1 ↑ (I/O in

setup time)

0——ns

20 TIOR Port Output Rise Time PIC18FXXXX — 10 25 ns

20A PIC18LFXXXX — — 60 ns VDD = 2.0V

21 TIOF Port Output Fall Time PIC18FXXXX — 10 25 ns

21A PIC18LFXXXX — — 60 ns VDD = 2.0V

22† TINP INT pin High or Low Time TCY ——ns

23† TRBP RB7:RB4 Change INT High or Low Time TCY ——ns

24† TRCP RC7:RC4 Change INT High or Low Time 20 ns

† These parameters are asynchronous events not related to any internal clock edges.

Note 1: Measurements are taken in RC mode, where CLKO output is 4 x TOSC.

PIC18F2585/2680/4585/4680

FIGURE 27-7: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND

POWER-UP TIMER TIMING

FIGURE 27-8: BROWN-OUT RESET TIMING

TABLE 27-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER

AND BROWN-OUT RESET REQUIREMENTS

Param.

No. Sym Characteristic Min Typ Max Units Conditions

30 TMCLMCLR Pulse Width (low) 2 — — μs

31 TWDT Watchdog Timer Time-out Period (no

postscaler)

3.4 4.00 4.6 ms

32 T

OST Oscillation Start-up Timer Period 1024 TOSC — 1024 TOSC —TOSC = OSC1 period

33 TPWRT Power-up Timer Period 55.6 65.5 75 ms

34 TIOZ I/O High-Impedance from MCLR Low

or Watchdog Timer Reset

—2— μs

35 TBOR Brown-out Reset Pulse Width 200 — — μsVDD ≤ BVDD (see D005)

36 TIRVST Time for Internal Reference Voltage to

become stable

—2050 μs

37 TLVD High/Low-Voltage Detect Pulse Width 200 — — μsVDD ≤ VLVD

38 TCSD CPU Start-up Time — 10 — μs

39 TIOBST Time for INTOSC to stabilize — 1 — μs

VDD

MCLR

Internal

POR

PWRT

Time-out

OSC

Time-out

Internal

Reset

Watchdog

Timer

Reset

I/O pins

Note: Refer to Figure 27-4 for load conditions.

VDD BVDD

35 VBGAP = 1.2V

VIRVST

Enable Internal

Internal Reference 36

Reference Voltage

Voltage Stable

PIC18F2585/2680/4585/4680

FIGURE 27-9: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS

TABLE 27-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS

Note: Refer to Figure 27-4 for load conditions.

T0CKI

T1OSO/T13CKI

TMR0 or

TMR1

Param

No. Sym Characteristic Min Max Units Conditions

40 TT0H T0CKI High Pulse Width No prescaler 0.5 TCY + 20 — ns

With prescaler 10 — ns

41 TT0L T0CKI Low Pulse Width No prescaler 0.5 TCY + 20 — ns

With prescaler 10 — ns

42 TT0P T0CKI Period No prescaler TCY + 10 — ns

With prescaler Greater of:

20 ns or

(TCY + 40)/N

— ns N = prescale value

(1, 2, 4,..., 256)

45 TT1H T13CKI High

Time

Synchronous, no prescaler 0.5 TCY + 20 — ns

Synchronous,

with prescaler

PIC18FXXXX 10 — ns

PIC18LFXXXX 25 — ns VDD = 2.0V

Asynchronous PIC18FXXXX 30 — ns

PIC18LFXXXX 50 — ns VDD = 2.0V

46 TT1L T13CKI Low

Time

Synchronous, no prescaler 0.5 TCY + 5 — ns

Synchronous,

with prescaler

PIC18FXXXX 10 — ns

PIC18LFXXXX 25 — ns VDD = 2.0V

Asynchronous PIC18FXXXX 30 — ns

PIC18LFXXXX 50 — ns VDD = 2.0V

47 TT1P T13CKI Input

Period

Synchronous Greater of:

20 ns or

(TCY + 40)/N

— ns N = prescale value

(1, 2, 4, 8)

Asynchronous 60 — ns

FT1 T13CKI Oscillator Input Frequency Range DC 50 kHz

48 T

CKE2TMRI Delay from External T13CKI Clock Edge to

Timer Increment

2 TOSC 7 TOSC —

PIC18F2585/2680/4585/4680

FIGURE 27-10: CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES)

TABLE 27-12: CAPTURE/COMPARE/PWM REQUIREMENTS (ALL CCP MODULES)

Note: Refer to Figure 27-4 for load conditions.

CCPx

(Capture Mode)

50 51

CCPx

53 54

(Compare or PWM Mode)

Param

No. Sym Characteristic Min Max Units Conditions

50 TCCL CCPx Input Low

Time

No prescaler 0.5 TCY + 20 — ns

With prescaler PIC18FXXXX 10 — ns

PIC18LFXXXX 20 — ns VDD = 2.0V

51 TCCH CCPx Input High

Time

No prescaler 0.5 TCY + 20 — ns

With prescaler PIC18FXXXX 10 — ns

PIC18LFXXXX 20 — ns VDD = 2.0V

52 TCCP CCPx Input Period 3 TCY + 40

—nsN = prescale

value (1,4 or 16)

53 TCCR CCPx Output Fall Time PIC18FXXXX — 25 ns

PIC18LFXXXX — 45 ns VDD = 2.0V

54 TCCF CCPx Output Fall Time PIC18FXXXX — 25 ns

PIC18LFXXXX — 45 ns VDD = 2.0V

PIC18F2585/2680/4585/4680

FIGURE 27-11: PARALLEL SLAVE PORT TIMING (PIC18F4585/4680)

TABLE 27-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4585/4680)

Note: Refer to Figure 27-4 for load conditions.

RE2/CS

RE0/RD

RE1/WR

RD7:RD0

Param.

No. Symbol Characteristic Min Max Units Conditions

62 TDTV2WRH Data In Valid before WR ↑ or CS ↑ (setup time) 20 — ns

63 TWRH2DTIWR ↑ or CS ↑ to Data–In Invalid

(hold time)

PIC18FXXXX 20 — ns

PIC18LFXXXX 35 — ns VDD = 2.0V

64 TRDL2DTVRD ↓ and CS ↓ to Data–Out Valid — 80 ns

65 TRDH2DTIRD ↑ or CS ↓ to Data–Out Invalid 10 30 ns

66 TIBFINH Inhibit of the IBF Flag bit being Cleared from WR ↑ or CS ↑—3 TCY

PIC18F2585/2680/4585/4680

FIGURE 27-12: EXAMPLE SPI MASTER MODE TIMING (CKE = 0)

TABLE 27-14: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0)

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

75, 76

MSb LSb

bit 6 - - - - - -1

MSb In LSb In

bit 6 - - - -1

Note: Refer to Figure 27-4 for load conditions.

Param

No. Symbol Characteristic Min Max Units Conditions

73 TDIV2SCH,

TDIV2SCL

Setup Time of SDI Data Input to SCK Edge 100 — ns

74 TSCH2DIL,

TSCL2DIL

Hold Time of SDI Data Input to SCK Edge 100 — ns

75 TDOR SDO Data Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX — 45 ns VDD = 2.0V

76 TDOF SDO Data Output Fall Time — 25 ns

78 TSCR SCK Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX — 45 ns VDD = 2.0V

79 TSCF SCK Output Fall Time — 25 ns

80 TSCH2DOV,

TSCL2DOV

SDO Data Output Valid after

SCK Edge

PIC18FXXXX — 50 ns

PIC18LFXXXX — 100 ns VDD = 2.0V

PIC18F2585/2680/4585/4680

FIGURE 27-13: EXAMPLE SPI MASTER MODE TIMING (CKE = 1)

TABLE 27-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1)

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

75, 76

MSb

MSb In

bit 6 - - - - - -1

LSb In

bit 6 - - - -1

LSb

Note: Refer to Figure 27-4 for load conditions.

Param.

No. Symbol Characteristic Min Max Units Conditions

73 TDIV2SCH,

TDIV2SCL

Setup Time of SDI Data Input to SCK Edge 100 — ns

74 T

SCH2DIL,

TSCL2DIL

Hold Time of SDI Data Input to SCK Edge 100 — ns

75 TDOR SDO Data Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX 45 ns VDD = 2.0V

76 TDOF SDO Data Output Fall Time — 25 ns

78 TSCR SCK Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX 45 ns VDD = 2.0V

79 TSCF SCK Output Fall Time — 25 ns

80 TSCH2DOV,

TSCL2DOV

SDO Data Output Valid after

SCK Edge

PIC18FXXXX — 50 ns

PIC18LFXXXX 100 ns VDD = 2.0V

81 TDOV2SCH,

TDOV2SCL

SDO Data Output Setup to SCK Edge T

CY —ns

PIC18F2585/2680/4585/4680

FIGURE 27-14: EXAMPLE SPI SLAVE MODE TIMING (CKE = 0)

TABLE 27-16: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE TIMING, CKE = 0)

Param

No. Symbol Characteristic Min Max Units Conditions

70 T

SSL2SCH,

TSSL2SCL

SS ↓ to SCK ↓ or SCK ↑ Input TCY —ns

71 T

SCH SCK Input High Time Continuous 1.25 TCY + 30 — ns

71A Single Byte 40 — ns (Note 1)

72 T

SCL SCK Input Low Time Continuous 1.25 TCY + 30 — ns

72A Single Byte 40 — ns (Note 1)

73 TDIV2SCH,

TDIV2SCL

Setup Time of SDI Data Input to SCK Edge 100 — ns

73A TB2BLast Clock Edge of Byte1 to the First Clock Edge of Byte 2 1.5 TCY + 40 — ns (Note 2)

74 T

SCH2DIL,

TSCL2DIL

Hold Time of SDI Data Input to SCK Edge 100 — ns

75 TDOR SDO Data Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX 45 ns VDD = 2.0V

76 TDOF SDO Data Output Fall Time — 25 ns

77 T

SSH2DOZSS ↑ to SDO Output High-Impedance 10 50 ns

80 T

SCH2DOV,

SCL2DOV

SDO Data Output Valid after SCK Edge PIC18FXXXX — 50 ns

PIC18LFXXXX 100 ns VDD = 2.0V

83 TscH2ssH,

Ts c L 2s s H

SS ↑ after SCK Edge 1.5 TCY + 40 — ns

Note 1: Requires the use of Parameter #73A.

2: Only if Parameter #71A and #72A are used.

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

75, 76 77

SDI

MSb LSb

bit 6 - - - - - -1

MSb In bit 6 - - - -1 LSb In

Note: Refer to Figure 27-4 for load conditions.

PIC18F2585/2680/4585/4680

FIGURE 27-15: EXAMPLE SPI SLAVE MODE TIMING (CKE = 1)

TABLE 27-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1)

Param

No. Symbol Characteristic Min Max Units Conditions

70 TSSL2SCH,

TSSL2SCL

SS ↓ to SCK ↓ or SCK ↑ Input TCY —ns

71 TSCH SCK Input High Time Continuous 1.25 TCY + 30 — ns

71A Single Byte 40 — ns (Note 1)

72 TSCL SCK Input Low Time Continuous 1.25 TCY + 30 — ns

72A Single Byte 40 — ns (Note 1)

73A TB2BLast Clock Edge of Byte 1 to the fIrst Clock Edge of Byte 2 1.5 TCY + 40 — ns (Note 2)

74 TSCH2DIL,

TSCL2DIL

Hold Time of SDI Data Input to SCK Edge 100 — ns

75 TDOR SDO Data Output Rise Time PIC18FXXXX — 25 ns

PIC18LFXXXX 45 ns VDD = 2.0V

76 TDOF SDO Data Output Fall Time — 25 ns

77 T

SSH2DOZSS↑ to SDO Output High-Impedance 10 50 ns

80 T

SCH2DOV,

SCL2DOV

SDO Data Output Valid after SCK

Edge

PIC18FXXXX — 50 ns

PIC18LFXXXX — 100 ns VDD = 2.0V

82 T

SSL2DOV SDO Data Output Valid after SS ↓

Edge

PIC18FXXXX — 50 ns

PIC18LFXXXX — 100 ns VDD = 2.0V

83 T

SCH2SSH,

SCL2SSH

SS ↑ after SCK Edge 1.5 TCY + 40 — ns

Note 1: Requires the use of Parameter #73A.

2: Only if Parameter #71A and #72A are used.

SCK

(CKP = 0)

SCK

(CKP = 1)

SDO

SDI

71 72

SDI

75, 76

MSb bit 6 - - - - - -1 LSb

MSb In bit 6 - - - -1 LSb In

Note: Refer to Figure 27-4 for load conditions.

PIC18F2585/2680/4585/4680

FIGURE 27-16: I2C™ BUS START/STOP BITS TIMING

TABLE 27-18: I2C™ BUS START/STOP BITS REQUIREMENTS (SLAVE MODE)

FIGURE 27-17: I2C™ BUS DATA TIMING

Note: Refer to Figure 27-4 for load conditions.

SCL

SDA

Start

Condition

Stop

Condition

Param.

No. Symbol Characteristic Min Max Units Conditions

90 T

SU:STA Start Condition 100 kHz mode 4700 — ns Only relevant for Repeated

Start condition

Setup Time 400 kHz mode 600 —

91 THD:STA Start Condition 100 kHz mode 4000 — ns After this period, the first

clock pulse is generated

Hold Time 400 kHz mode 600 —

92 TSU:STO Stop Condition 100 kHz mode 4700 — ns

Setup Time 400 kHz mode 600 —

93 THD:STO Stop Condition 100 kHz mode 4000 — ns

Hold Time 400 kHz mode 600 —

Note: Refer to Figure 27-4 for load conditions.

91 92

100

101

103

106 107

109 109

110

102

SCL

SDA

Out

PIC18F2585/2680/4585/4680

TABLE 27-19: I2C™ BUS DATA REQUIREMENTS (SLAVE MODE)

Param.

No. Symbol Characteristic Min Max Units Conditions

100 THIGH Clock High Time 100 kHz mode 4.0 — μs PIC18FXXXX must operate

at a minimum of 1.5 MHz

400 kHz mode 0.6 — μs PIC18FXXXX must operate

at a minimum of 10 MHz

SSP module 1.5 T

CY —

101 TLOW Clock Low Time 100 kHz mode 4.7 — μs PIC18FXXXX must operate

at a minimum of 1.5 MHz

400 kHz mode 1.3 — μs PIC18FXXXX must operate

at a minimum of 10 MHz

SSP module 1.5 T

CY —

102 TRSDA and SCL Rise

Time

100 kHz mode — 1000 ns

400 kHz mode 20 + 0.1 CB300 ns CB is specified to be from

10 to 400 pF

103 TFSDA and SCL Fall

Time

100 kHz mode — 300 ns

400 kHz mode 20 + 0.1 CB300 ns CB is specified to be from

10 to 400 pF

90 TSU:STA Start Condition

Setup Time

100 kHz mode 4.7 — μs Only relevant for Repeated

Start condition

400 kHz mode 0.6 — μs

91 THD:STA Start Condition

Hold Time

100 kHz mode 4.0 — μs After this period, the first

clock pulse is generated

400 kHz mode 0.6 — μs

106 THD:DAT Data Input Hold

Time

100 kHz mode 0 — ns

400 kHz mode 0 0.9 μs

107 TSU:DAT Data Input Setup

Time

100 kHz mode 250 — ns (Note 2)

400 kHz mode 100 — ns

92 TSU:STO Stop Condition

Setup Time

100 kHz mode 4.7 — μs

400 kHz mode 0.6 — μs

109 TAA Output Valid from

Clock

100 kHz mode — 3500 ns (Note 1)

400 kHz mode — — ns

110 TBUF Bus Free Time 100 kHz mode 4.7 — μs Time the bus must be free

before a new transmission

can start

400 kHz mode 1.3 — μs

D102 CBBus Capacitive Loading — 400 pF

Note 1: As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region

(min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions.

2: A Fast mode I2C™ bus device can be used in a Standard mode I2C bus system but the requirement,

TSU:DAT ≥250 ns, must then be met. This will automatically be the case if the device does not stretch the

LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must out-

put the next data bit to the SDA line,

TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the Standard mode I2C bus specification), before

the SCL line is released.

PIC18F2585/2680/4585/4680

FIGURE 27-18: MASTER SSP I2C™ BUS START/STOP BITS TIMING WAVEFORMS

TABLE 27-20: MASTER SSP I2C™ BUS START/STOP BITS REQUIREMENTS

FIGURE 27-19: MASTER SSP I2C™ BUS DATA TIMING

Note: Refer to Figure 27-4 for load conditions.

91 93

SCL

SDA

Start

Condition

Stop

Condition

90 92

Param.

No. Symbol Characteristic Min Max Units Conditions

90 TSU:STA Start condition 100 kHz mode 2(TOSC)(BRG + 1) — ns Only relevant for

Repeated Start condition

Setup Time 400 kHz mode 2(TOSC)(BRG + 1) —

1 MHz mode(1) 2(TOSC)(BRG + 1) —

91 THD:STA Start Condition 100 kHz mode 2(TOSC)(BRG + 1) — ns After this period, the first

clock pulse is generated

Hold Time 400 kHz mode 2(TOSC)(BRG + 1) —

1 MHz mode(1) 2(TOSC)(BRG + 1) —

92 TSU:STO Stop Condition 100 kHz mode 2(TOSC)(BRG + 1) — ns

Setup Time 400 kHz mode 2(TOSC)(BRG + 1) —

1 MHz mode(1) 2(TOSC)(BRG + 1) —

93 THD:STO Stop Condition 100 kHz mode 2(TOSC)(BRG + 1) — ns

Hold Time 400 kHz mode 2(TOSC)(BRG + 1) —

1 MHz mode(1) 2(TOSC)(BRG + 1) —

Note 1: Maximum pin capacitance = 10 pF for all I2C pins.

Note: Refer to Figure 27-4 for load conditions.

90 91 92

100

101

103

106 107

109 109 110

102

SCL

SDA

Out

PIC18F2585/2680/4585/4680

TABLE 27-21: MASTER SSP I2C™ BUS DATA REQUIREMENTS

Param.

No. Symbol Characteristic Min Max Units Conditions

100 THIGH Clock High

Time

100 kHz mode 2(TOSC)(BRG + 1) — ms

400 kHz mode 2(T

OSC)(BRG + 1) — ms

1 MHz mode(1) 2(TOSC)(BRG + 1) — ms

101 TLOW Clock Low Time 100 kHz mode 2(TOSC)(BRG + 1) — ms

400 kHz mode 2(T

OSC)(BRG + 1) — ms

1 MHz mode(1) 2(TOSC)(BRG + 1) — ms

102 TRSDA and SCL

Rise Time

100 kHz mode — 1000 ns CB is specified to be from

10 to 400 pF

400 kHz mode 20 + 0.1 CB300 ns

1 MHz mode(1) — 300 ns

103 TFSDA and SCL

Fall Time

100 kHz mode — 300 ns CB is specified to be from

10 to 400 pF

400 kHz mode 20 + 0.1 CB 300 ns

1 MHz mode(1) — 100 ns

90 TSU:STA Start Condition

Setup Time

100 kHz mode 2(TOSC)(BRG + 1) — ms Only relevant for

Repeated Start

condition

400 kHz mode 2(T

OSC)(BRG + 1) — ms

1 MHz mode(1) 2(TOSC)(BRG + 1) — ms

91 THD:STA Start Condition

Hold Time

100 kHz mode 2(TOSC)(BRG + 1) — ms After this period, the first

clock pulse is generated

400 kHz mode 2(T

OSC)(BRG + 1) — ms

1 MHz mode(1) 2(TOSC)(BRG + 1) — ms

106 THD:DAT Data Input

Hold Time

100 kHz mode 0 — ns

400 kHz mode 0 0.9 ms

107 T

SU:DAT Data Input

Setup Time

100 kHz mode 250 — ns (Note 2)

400 kHz mode 100 — ns

92 T

SU:STO Stop Condition

Setup Time

100 kHz mode 2(TOSC)(BRG + 1) — ms

400 kHz mode 2(TOSC)(BRG + 1) — ms

1 MHz mode(1) 2(TOSC)(BRG + 1) — ms

109 T

AA Output Valid

from Clock

100 kHz mode — 3500 ns

400 kHz mode — 1000 ns

1 MHz mode(1) ——ns

110 TBUF Bus Free Time 100 kHz mode 4.7 — ms Time the bus must be free

before a new transmission

can start

400 kHz mode 1.3 — ms

D102 CBBus Capacitive Loading — 400 pF

Note 1: Maximum pin capacitance = 10 pF for all I2C pins.

2: A Fast mode I2C™ bus device can be used in a Standard mode I2C bus system, but parameter

#107 ≥250 ns must then be met. This will automatically be the case if the device does not stretch the LOW

period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the

next data bit to the SDA line, parameter #102 + parameter #107 = 1000 + 250 = 1250 ns (for 100 kHz

mode), before the SCL line is released.

PIC18F2585/2680/4585/4680

FIGURE 27-20: EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING

TABLE 27-22: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS

FIGURE 27-21: EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING

TABLE 27-23: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS

121 121

120 122

RC6/TX/CK

RC7/RX/DT

Note: Refer to Figure 27-4 for load conditions.

Param

No. Symbol Characteristic Min Max Units Conditions

120 T

CKH2DTV SYNC XMIT (MASTER & SLAVE)

Clock High to Data Out Valid PIC18FXXXX — 40 ns

PIC18LFXXXX — 100 ns VDD = 2.0V

121 TCKRF Clock Out Rise Time and Fall Time

(Master mode)

PIC18FXXXX — 20 ns

PIC18LFXXXX — 50 ns VDD = 2.0V

122 TDTRF Data Out Rise Time and Fall Time PIC18FXXXX — 20 ns

PIC18LFXXXX — 50 ns VDD = 2.0V

125

126

RC6/TX/CK

RC7/RX/DT

Note: Refer to Figure 27-4 for load conditions.

Param.

No. Symbol Characteristic Min Max Units Conditions

125 TDTV2CKL SYNC RCV (MASTER & SLAVE)

Data Hold before CK ↓ (DT hold time) 10 — ns

126 TCKL2DTL Data Hold after CK ↓ (DT hold time) 15 — ns

PIC18F2585/2680/4585/4680

TABLE 27-24: A/D CONVERTER CHARACTERISTICS: PIC18F2585/2680/4585/4680 (INDUSTRIAL)

PIC18LF2585/2680/4585/4680 (INDUSTRIAL)

Param

No. Sym Characteristic Min Typ Max Units Conditions

A01 NRResolution — — 10 bit ΔVREF ≥ 3.0V

A03 EIL Integral Linearity Error — — <±1 LSb ΔVREF ≥ 3.0V

A04 EDL Differential Linearity Error — — <±1 LSb ΔVREF ≥ 3.0V

A06 EOFF Offset Error — — <±1 LSb ΔVREF ≥ 3.0V

A07 EGN Gain Error — — <±1 LSb ΔVREF ≥ 3.0V

A10 — Monotonicity Guaranteed(1) —

A20 ΔVREF Reference Voltage Range

(VREFH – VREFL)

3—AV

DD – AVSS V For 10-bit resolution

A21 VREFH Reference Voltage High AVSS + 3.0V — AVDD + 0.3V V For 10-bit resolution

A22 VREFL Reference Voltage Low AVSS – 0.3V — AVDD – 3.0V V For 10-bit resolution

A25 VAIN Analog Input Voltage VREFL —VREFH V

A28 AVDD Analog Supply Voltage VDD – 0.3 — VDD + 0.3 V

A29 AVSS Analog Supply Voltage VSS – 0.3 — VSS + 0.3 V

A30 ZAIN Recommended Impedance of

Analog Voltage Source

——2.5kΩ

A40 IAD A/D Conversion

Current (VDD)

PIC18FXXXX — 180 — μA Average current

consumption when

A/D is on (Note 2)

PIC18LFXXXX — 90 — μAV

DD = 2.0V;

average current

consumption when

A/D is on (Note 2)

A50 IREF VREF Input Current (Note 3) —

—

±5

±150

μA

During VAIN acquisition.

During A/D conversion

cycle.

Note 1: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes.

2: When A/D is off, it will not consume any current other than minor leakage current. The power-down current

spec includes any such leakage from the A/D module.

3: VREFH current is from RA3/AN3/VREF+ pin or AVDD, whichever is selected as the VREFH source.

VREFL current is from RA2/AN2/VREF- pin or AVSS, whichever is selected as the VREFL source.

PIC18F2585/2680/4585/4680

FIGURE 27-22: A/D CONVERSION TIMING

TABLE 27-25: A/D CONVERSION REQUIREMENTS

131

130

132

BSF ADCON0, GO

A/D CLK(1)

A/D DATA

ADRES

ADIF

SAMPLE

OLD_DATA

SAMPLING STOPPED

DONE

NEW_DATA

(Note 2)

987 21 0

Note 1: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts.

This allows the SLEEP instruction to be executed.

2: This is a minimal RC delay (typically 100 ns), which also disconnects the holding capacitor from the analog input.

. . . . . .

TCY

Param

No. Symbol Characteristic Min Max Units Conditions

130 TAD A/D Clock Period PIC18FXXXX 0.7 25.0(1) μsTOSC based, VREF ≥ 3.0V

PIC18LFXXXX 1.4 25.0(1) μsVDD = 2.0V;

TOSC based, VREF full range

PIC18FXXXX — 1 μs A/D RC mode

PIC18LFXXXX — 3 μsV

DD = 2.0V; A/D RC mode

131 TCNV Conversion Time

(not including acquisition time) (Note 2)

11 12 TAD

132 TACQ Acquisition Time (Note 3) 1.4 — μs-40°C to +85°C

135 TSWC Switching Time from Convert → Sample — (Note 4)

136 TAMP Amplifier Settling Time (Note 5) 1—μs This may be used if the “new” input

voltage has not changed by more

than 1 LSb (i.e., 5 mV @ 5.12V)

from the last sampled voltage (as

stated on CHOLD).

Note 1: The time of the A/D clock period is dependent on the device frequency and the TAD clock divider.

2: ADRES register may be read on the following TCY cycle.

3: The time for the holding capacitor to acquire the “New” input voltage when the voltage changes full scale

after the conversion (AVDD to AVSS or AVSS to AVDD). The source impedance (

) on the input channels is

50Ω.

4: On the following cycle of the device clock.

5: See Section 19.0 “10-Bit Analog-to-Digital Converter (A/D) Module” for minimum conditions when input

voltage has changed more than 1 LSb.

PIC18F2585/2680/4585/4680

28.0 DC AND AC

CHARACTERISTICS GRAPHS

AND TABLES

Graphs and tables are not available at this time.

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

29.0 PACKAGING INFORMATION

29.1 Package Marking Information

28-Lead PDIP (Skinny DIP)

XXXXXXXXXXXXXXXXX

YYWWNNN

Example

PIC18F2680-I/SP

0710017

28-Lead SOIC

XXXXXXXXXXXXXXXXXXXX

YYWWNNN

Example

PIC18F2680-E/SO

0710017

40-Lead PDIP

XXXXXXXXXXXXXXXXXX

YYWWNNN

Example

PIC18F4585-I/P

0710017

Legend: XX...X Customer-specific information

Y Year code (last digit of calendar year)

YY Year code (last 2 digits of calendar year)

WW Week code (week of January 1 is week ‘01’)

NNN Alphanumeric traceability code

Pb-free JEDEC designator for Matte Tin (Sn)

*This package is Pb-free. The Pb-free JEDEC designator ( )

can be found on the outer packaging for this package.

Note: In the event the full Microchip part number cannot be marked on one line, it will

be carried over to the next line, thus limiting the number of available

characters for customer-specific information.

PIC18F2585/2680/4585/4680

29.1 Package Marking Information (Continued)

44-Lead TQFP

XXXXXXXXXX

YYWWNNN

Example

PIC18F4585

-I/PT0710017

XXXXXXXXXX

44-Lead QFN

XXXXXXXXXX

YYWWNNN

PIC18F4680

Example

-I/ML

0710017

PIC18F2585/2680/4585/4680

29.2 Package Details

The following sections give the technical details of the packages.

28-Lead Skinny Plastic Dual In-Line (SP) – 300 mil Body [SPDIP]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. § Significant Characteristic.

3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" per side.

4. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

Units INCHES

Dimension Limits MIN NOM MAX

Number of Pins N 28

Pitch e .100 BSC

Top to Seating Plane A – – .200

Molded Package Thickness A2 .120 .135 .150

Base to Seating Plane A1 .015 – –

Shoulder to Shoulder Width E .290 .310 .335

Molded Package Width E1 .240 .285 .295

Overall Length D 1.345 1.365 1.400

Tip to Seating Plane L .110 .130 .150

Lead Thickness c .008 .010 .015

Upper Lead Width b1 .040 .050 .070

Lower Lead Width b .014 .018 .022

Overall Row Spacing § eB – – .430

NOTE 1

Microchip Technology Drawing C04-070B

PIC18F2585/2680/4585/4680

28-Lead Plastic Small Outline (SO) – Wide, 7.50 mm Body [SOIC]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. § Significant Characteristic.

3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.

4. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

Units MILLMETERS

Dimension Limits MIN NOM MAX

Number of Pins N 28

Pitch e 1.27 BSC

Overall Height A – – 2.65

Molded Package Thickness A2 2.05 – –

Standoff § A1 0.10 – 0.30

Overall Width E 10.30 BSC

Molded Package Width E1 7.50 BSC

Overall Length D 17.90 BSC

Chamfer (optional) h 0.25 – 0.75

Foot Length L 0.40 – 1.27

Footprint L1 1.40 REF

Foot Angle Top φ0° – 8°

Lead Thickness c 0.18 – 0.33

Lead Width b 0.31 – 0.51

Mold Draft Angle Top α5° – 15°

Mold Draft Angle Bottom β5° – 15°

NOTE 1

123

Microchip Technology Drawing C04-052B

PIC18F2585/2680/4585/4680

40-Lead Plastic Dual In-Line (P) – 600 mil Body [PDIP]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. § Significant Characteristic.

3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010" per side.

4. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

Units INCHES

Dimension Limits MIN NOM MAX

Number of Pins N 40

Pitch e .100 BSC

Top to Seating Plane A – – .250

Molded Package Thickness A2 .125 – .195

Base to Seating Plane A1 .015 – –

Shoulder to Shoulder Width E .590 – .625

Molded Package Width E1 .485 – .580

Overall Length D 1.980 – 2.095

Tip to Seating Plane L .115 – .200

Lead Thickness c .008 – .015

Upper Lead Width b1 .030 – .070

Lower Lead Width b .014 – .023

Overall Row Spacing § eB – – .700

NOTE 1

123

A1 b1

Microchip Technology Drawing C04-016B

PIC18F2585/2680/4585/4680

44-Lead Plastic Thin Quad Flatpack (PT) – 10x10x1 mm Body, 2.00 mm Footprint [TQFP]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. Chamfers at corners are optional; size may vary.

3. Dimensions D1 and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.25 mm per side.

4. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

Units MILLIMETERS

Dimension Limits MIN NOM MAX

Number of Leads N 44

Lead Pitch e 0.80 BSC

Overall Height A – – 1.20

Molded Package Thickness A2 0.95 1.00 1.05

Standoff A1 0.05 – 0.15

Foot Length L 0.45 0.60 0.75

Footprint L1 1.00 REF

Foot Angle φ0° 3.5° 7°

Overall Width E 12.00 BSC

Overall Length D 12.00 BSC

Molded Package Width E1 10.00 BSC

Molded Package Length D1 10.00 BSC

Lead Thickness c 0.09 – 0.20

Lead Width b 0.30 0.37 0.45

Mold Draft Angle Top α11° 12° 13°

Mold Draft Angle Bottom β11° 12° 13°

NOTE 1 NOTE 2

123

Microchip Technology Drawing C04-076B

PIC18F2585/2680/4585/4680

44-Lead Plastic Quad Flat, No Lead Package (ML) – 8x8 mm Body [QFN]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. Package is saw singulated.

3. Dimensioning and tolerancing per ASME Y14.5M.

BSC: Basic Dimension. Theoretically exact value shown without tolerances.

REF: Reference Dimension, usually without tolerance, for information purposes only.

Note: For the most current package drawings, please see the Microchip Packaging Specification located at

http://www.microchip.com/packaging

Units MILLIMETERS

Dimension Limits MIN NOM MAX

Number of Pins N 44

Pitch e 0.65 BSC

Overall Height A 0.80 0.90 1.00

Standoff A1 0.00 0.02 0.05

Contact Thickness A3 0.20 REF

Overall Width E 8.00 BSC

Exposed Pad Width E2 6.30 6.45 6.80

Overall Length D 8.00 BSC

Exposed Pad Length D2 6.30 6.45 6.80

Contact Width b 0.25 0.30 0.38

Contact Length L 0.30 0.40 0.50

Contact-to-Exposed Pad K 0.20 – –

DEXPOSED

PAD

NOTE 1

BOTTOM VIEW

TOP VIEW

A3A1

Microchip Technology Drawing C04-103B

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

APPENDIX A: REVISION HISTORY

Revision A (December 2003)

Original data sheet for PIC18F2585/2680/4585/4680

devices.

Revision B (July 2004)

This update includes updates to the Electrical Specifi-

cations in Section 27.0 and includes minor corrections

to the data sheet text.

Revision C (January 2007)

Major edits to Section 27.0 “Electrical Characteris-

tics”. Packaging diagrams have been updated and

minor edits to text have been made throughout

document.

APPENDIX B: DEVICE

DIFFERENCES

The differences between the devices listed in this data

sheet are shown in Table B-1.

TABLE B-1: DEVICE DIFFERENCES

Features PIC18F2585 PIC18F2680 PIC18F4585 PIC18F4680

Program Memory (Bytes) 49152 65536 49152 65536

Program Memory (Instructions) 24576 32768 24576 32768

Interrupt Sources 27 27 28 28

I/O Ports Ports A, B, C, (E) Ports A, B, C, (E) Ports A, B, C, D, E Ports A, B, C, D, E

Capture/Compare/PWM Modules 1 1 1 1

Enhanced Capture/Compare/

PWM Modules

001 1

Parallel Communications (PSP) No No Yes Yes

10-bit Analog-to-Digital Module 8 input channels 8 input channels 11 input channels 11 input channels

Packages 28-pin PDIP

28-pin SOIC

28-pin PDIP

28-pin SOIC

40-pin PDIP

44-pin TQFP

44-pin QFN

40-pin PDIP

44-pin TQFP

44-pin QFN

PIC18F2585/2680/4585/4680

APPENDIX C: CONVERSION

CONSIDERATIONS

This appendix discusses the considerations for

converting from previous versions of a device to the

ones listed in this data sheet. Typically, these changes

are due to the differences in the process technology

used. An example of this type of conversion is from a

PIC16C74A to a PIC16C74B.

Not Applicable

APPENDIX D: MIGRATION FROM

BASELINE TO

ENHANCED DEVICES

This section discusses how to migrate from a Baseline

device (i.e., PIC16C5X) to an Enhanced MCU device

(i.e., PIC18FXXX).

The following are the list of modifications over the

PIC16C5X microcontroller family:

Not Currently Available

PIC18F2585/2680/4585/4680

APPENDIX E: MIGRATION FROM

MID-RANGE TO

ENHANCED DEVICES

A detailed discussion of the differences between the

mid-range MCU devices (i.e., PIC16CXXX) and the

enhanced devices (i.e., PIC18FXXX) is provided in

AN716, “Migrating Designs from PIC16C74A/74B to

PIC18C442

.” The changes discussed, while device

specific, are generally applicable to all mid-range to

enhanced device migrations.

This Application Note is available as Literature Number

DS00716.

APPENDIX F: MIGRATION FROM

HIGH-END TO

ENHANCED DEVICES

A detailed discussion of the migration pathway and

differences between the high-end MCU devices (i.e.,

PIC17CXXX) and the enhanced devices (i.e.,

PIC18FXXX) is provided in

AN726, “PIC17CXXX to

PIC18CXXX Migration

.” This Application Note is

available as Literature Number DS00726.

PIC18F2585/2680/4585/4680

NOTES:

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 465
PIC18F2585/2680/4585/4680
INDEX
A
A/D ................................................................................... 247
Acquisition Requirements  ........................................ 252
ADCON0 Register .................................................... 247
ADCON1 Register .................................................... 247
ADCON2 Register .................................................... 247
ADRESH Register ............................................ 247, 250
ADRESL Register  .................................................... 247
Analog Port Pins, Configuring .................................. 254
Associated Registers  ............................................... 256
Automatic Acquisition Time ...................................... 253
Configuring the Module ............................................ 251
Conversion Clock (TAD) ........................................... 253
Conversion Status (GO/DONE Bit)  .......................... 250
Conversions ............................................................. 255
Converter Characteristics  ........................................ 449
Converter Interrupt, Configuring  .............................. 251
Operation in Power Managed Modes  ...................... 254
Special Event Trigger (ECCP1)  ....................... 174, 256
Use of the CCP1 Trigger .......................................... 256
Absolute Maximum Ratings  ............................................. 415
AC (Timing) Characteristics  ............................................. 431
Load Conditions for Device 
Timing Specifications ....................................... 432
Parameter Symbology  ............................................. 431
Temperature and Voltage Specifications ................. 432
Timing Conditions  .................................................... 432
Access Bank  ...................................................................... 69
Mapping with Indexed Literal Offset Mode ................. 93
ACKSTAT ........................................................................ 217
ACKSTAT Status Flag  ..................................................... 217
ADCON0 Register ............................................................ 247
GO/DONE Bit ........................................................... 250
ADCON1 Register ............................................................ 247
ADCON2 Register ............................................................ 247
ADDFSR .......................................................................... 404
ADDLW ............................................................................ 367
ADDULNK ........................................................................ 404
ADDWF ............................................................................ 367
ADDWFC ......................................................................... 368
ADRESH Register ............................................................ 247
ADRESL Register  .................................................... 247, 250
Analog-to-Digital Converter. 
See
 A/D.
and BSR ............................................................................. 93
ANDLW ............................................................................ 368
ANDWF ............................................................................ 369
Assembler
MPASM Assembler .................................................. 412
Auto-Wake-up on Sync Break Character ......................... 240
B
Bank Select Register (BSR) ............................................... 67
Baud Rate Generator ....................................................... 213
Baud Rate Generator (BRG) ............................................ 231
BC .................................................................................... 369
BCF .................................................................................. 370
BF .................................................................................... 217
BF Status Flag  ................................................................. 217
Bit Timing Configuration Registers
BRGCON1 ............................................................... 338
BRGCON2 ............................................................... 338
BRGCON3 ............................................................... 338
Block Diagrams
A/D ........................................................................... 250
Analog Input Model .................................................. 251
Baud Rate Generator  .............................................. 213
CAN Buffers and Protocol Engine  ........................... 274
Capture Mode Operation  ......................................... 166
Comparator Analog Input Model .............................. 261
Comparator I/O Operating Modes  ........................... 258
Comparator Output .................................................. 260
Comparator Voltage Reference ............................... 264
Compare Mode Operation  ....................................... 167
Device Clock .............................................................. 28
Enhanced PWM ....................................................... 175
EUSART Receive .................................................... 238
EUSART Transmit  ................................................... 236
External Power-on Reset Circuit 
(Slow VDD Power-up)  ........................................ 43
Fail-Safe Clock Monitor  ........................................... 355
Generic I/O Port Operation ...................................... 129
High/Low-Voltage Detect with External Input  .......... 268
MSSP (I2C Master Mode) ........................................ 211
MSSP (I2C Mode) .................................................... 196
MSSP (SPI Mode)  ................................................... 187
On-Chip Reset Circuit ................................................ 41
PIC18F2585/2680 ..................................................... 10
PIC18F4585/4680 ..................................................... 11
PLL (HS Mode) .......................................................... 25
PORTD and PORTE (Parallel Slave Port) ............... 144
PWM Operation (Simplified)  .................................... 169
Reads from Flash Program Memory  ......................... 99
Single Comparator ................................................... 259
Table Read Operation  ............................................... 95
Table Write Operation  ............................................... 96
Table Writes to Flash Program Memory .................. 101
Timer0 in 16-Bit Mode  ............................................. 148
Timer0 in 8-Bit Mode  ............................................... 148
Timer1 ..................................................................... 152
Timer1 (16-Bit Read/Write Mode) ............................ 152
Timer2 ..................................................................... 158
Timer3 ..................................................................... 160
Timer3 (16-Bit Read/Write Mode) ............................ 160
Voltage Reference Output Buffer Example  ............. 265
Watchdog Timer  ...................................................... 352
BN .................................................................................... 370
BNC ................................................................................. 371
BNN ................................................................................. 371
BNOV .............................................................................. 372
BNZ ................................................................................. 372
BOR. 
See
 Brown-out Reset.
BOV ................................................................................. 375
BRA ................................................................................. 373
BRG. 
See 
Baud Rate Generator.
Brown-out Reset (BOR) ..................................................... 44
Detecting ................................................................... 44
Disabling in Sleep mode ............................................ 44
Software Enabled  ...................................................... 44
BSF .................................................................................. 373
BTFSC ............................................................................. 374
BTFSS ............................................................................. 374
BTG ................................................................................. 375
BZ .................................................................................... 376

PIC18F2585/2680/4585/4680
DS39625C-page 466 Preliminary © 2007 Microchip Technology Inc.
C
C Compilers
MPLAB C18  ............................................................. 412
MPLAB C30  ............................................................. 412
CALL ................................................................................ 376
CALLW .............................................................................405
Capture (CCP1 Module) ................................................... 165
Associated Registers  ...............................................168
CCP1 Pin Configuration ........................................... 165
Software Interrupt  .................................................... 165
Timer1/Timer3 Mode Selection ................................ 165
Capture (ECCP1 Module)  ................................................ 174
ECCPR1H:ECCPR1L Registers  ..............................165
Capture/Compare/PWM (CCP1) ...................................... 163
Capture Mode.
 See
 Capture.
CCP1 Mode and Timer Resources  ..........................164
CCPR1H or ECCPR1H Register  ............................. 164
CCPR1L or ECCPR1L Register ...............................164
Compare Mode.
 See
 Compare.
Interaction Between CCP1 and ECCP1 
for Timer Resources  ........................................ 164
Module Configuration ...............................................164
PWM Mode.
 See
 PWM.
Clock Sources .................................................................... 28
Selecting the 31 kHz Source ...................................... 29
Selection Using OSCCON Register ...........................29
CLRF ................................................................................ 377
CLRWDT ..........................................................................377
Code Examples
16 x 16 Signed Multiply Routine  ..............................112
16 x 16 Unsigned Multiply Routine  .......................... 112
8 x 8 Signed Multiply Routine  .................................. 111
8 x 8 Unsigned Multiply Routine  ..............................111
Changing Between Capture Prescalers  ................... 165
Changing to Configuration Mode  ............................. 278
Computed GOTO Using an Offset Value ................... 64
Data EEPROM Read  ...............................................107
Data EEPROM Refresh Routine ..............................108
Data EEPROM Write  ...............................................107
Erasing a Flash Program Memory Row  ...................100
Fast Register Stack ....................................................64
How to Clear RAM (Bank 1) Using 
Indirect Addressing  ............................................88
Implementing a Real-Time Clock Using 
a Timer1 Interrupt Service  ...............................155
Initializing PORTA ....................................................129
Initializing PORTB ....................................................132
Initializing PORTC .................................................... 135
Initializing PORTD .................................................... 138
Initializing PORTE ....................................................141
Loading the SSPBUF (SSPSR) Register ................. 190
Reading a CAN Message  ........................................ 293
Reading a Flash Program Memory Word  .................. 99
Saving Status, WREG and 
BSR Registers in RAM .....................................128
Transmitting a CAN Message Using 
Banked Method ................................................ 286
Transmitting a CAN Message 
Using WIN Bits .................................................286
WIN and ICODE Bits Usage in Interrupt Service 
Routine to Access TX/RX Buffers  .................... 278
Writing to Flash Program Memory  ................... 102–103
Code Protection  ............................................................... 343
COMF ............................................................................... 378
Comparator ...................................................................... 257
Analog Input Connection Considerations  ................ 261
Associated Registers ............................................... 261
Configuration ........................................................... 258
Effects of a Reset  .................................................... 260
Interrupts ................................................................. 260
Operation ................................................................. 259
Operation During Sleep  ........................................... 260
Outputs .................................................................... 259
Reference ................................................................ 259
External Signal  ................................................ 259
Internal Signal .................................................. 259
Response Time ........................................................ 259
Comparator Specifications ............................................... 429
Comparator Voltage Reference  ....................................... 263
Accuracy and Error .................................................. 264
Associated Registers ............................................... 265
Configuring .............................................................. 263
Connection Considerations ...................................... 264
Effects of a Reset  .................................................... 264
Operation During Sleep  ........................................... 264
Compare (CCP Module)
Special Event Trigger  .............................................. 161
Compare (CCP1 Module)  ................................................ 167
Associated Registers ............................................... 168
CCP1 Pin Configuration ........................................... 167
CCPR1 Register  ...................................................... 167
Software Interrupt  .................................................... 167
Special Event Trigger  .............................................. 167
Timer1/Timer3 Mode Selection ................................ 167
Compare (ECCP Module) ................................................ 174
Compare (ECCP1 Module)
Special Event Trigger  ...................................... 174, 256
Configuration Bits  ............................................................ 343
Configuration Mode  ......................................................... 324
Configuration Register Protection .................................... 360
Context Saving During Interrupts ..................................... 128
Conversion Considerations .............................................. 462
CPFSEQ .......................................................................... 378
CPFSGT .......................................................................... 379
CPFSLT ........................................................................... 379
Crystal Oscillator/Ceramic Resonator ................................ 23
Customer Change Notification Service  ............................ 476
Customer Notification Service  ......................................... 476
Customer Support ............................................................ 476
D
Data Addressing Modes  .................................................... 88
Comparing Addressing Modes with the 
Extended Instruction Set Enabled  ..................... 92
Direct ......................................................................... 88
Indexed Literal Offset  ................................................ 91
Indirect ....................................................................... 88
Inherent and Literal .................................................... 88
Data EEPROM
Code Protection  ....................................................... 360
Data EEPROM Memory ................................................... 105
Associated Registers ............................................... 109
EEADR and EEADRH Registers  ............................. 105
EECON1 and EECON2 Registers ........................... 105
Operation During Code-Protect  ............................... 108
Protection Against Spurious Write ........................... 108
Reading ................................................................... 107
Using ....................................................................... 108
Write Verify  .............................................................. 107
Writing ..................................................................... 107

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 467
PIC18F2585/2680/4585/4680
Data Memory  ..................................................................... 67
Access Bank  .............................................................. 69
and the Extended Instruction Set ............................... 91
Bank Select Register (BSR) ....................................... 67
General Purpose Registers ........................................ 69
Map for PIC18F2X8X/4X8X ....................................... 68
Special Function Registers  ........................................ 70
DAW ................................................................................. 380
DC and AC Characteristics  .............................................. 451
DC Characteristics  ........................................................... 426
Power-Down and Supply Current  ............................ 418
Supply Voltage ......................................................... 417
DCFSNZ .......................................................................... 381
DECF ............................................................................... 380
DECFSZ ........................................................................... 381
Development Support  ...................................................... 411
Device Differences ........................................................... 461
Device Overview  .................................................................. 7
Features (table) ............................................................ 9
New Core Features ...................................................... 7
Device Reset Timers .......................................................... 45
Oscillator Start-up Timer (OST)  ................................. 45
PLL Lock Time-out ..................................................... 45
Power-up Timer (PWRT)  ........................................... 45
Direct Addressing ............................................................... 89
Disable Mode  ................................................................... 324
E
ECAN Technology  ........................................................... 273
Baud Rate Setting .................................................... 332
Bit Time Partitioning ................................................. 332
Bit Timing Configuration Registers  .......................... 338
Calculating TQ, Nominal Bit Rate 
and Nominal Bit Time  ...................................... 335
CAN Baud Rate Registers  ....................................... 311
CAN Control and Status Registers  .......................... 275
CAN Controller Register Map  .................................. 319
CAN I/O Control Register ......................................... 314
CAN Interrupt Registers ........................................... 315
CAN Interrupts  ......................................................... 339
Acknowledge ................................................... 341
Bus Activity Wake-up ....................................... 341
Bus-Off ............................................................. 341
Code Bits  ......................................................... 340
Error ................................................................. 341
Message Error  ................................................. 340
Receive ............................................................ 340
Receiver Bus Passive ...................................... 341
Receiver Overflow  ........................................... 341
Receiver Warning  ............................................ 341
Transmit ........................................................... 340
Transmitter Bus Passive .................................. 341
Transmitter Warning  ........................................ 341
CAN Message Buffers  ............................................. 326
Dedicated Receive ........................................... 326
Dedicated Transmit .......................................... 326
Programmable Auto-RTR  ................................ 327
Programmable Transmit/Receive  .................... 326
CAN Message Transmission  ................................... 327
Aborting ........................................................... 327
Initiating ........................................................... 327
Priority .............................................................. 328
CAN Modes of Operation ......................................... 324
CAN Registers  ......................................................... 275
Configuration Mode  ................................................. 324
Dedicated CAN Receive Buffer Registers  ............... 287
Dedicated CAN Transmit Buffer Registers  .............. 282
Disable Mode ........................................................... 324
Error Detection  ........................................................ 338
Acknowledge ................................................... 338
Bit .................................................................... 338
CRC ................................................................. 338
Error Modes and Counters  .............................. 338
Error States  ..................................................... 338
Form ................................................................ 338
Stuff Bit  ............................................................ 338
Error Modes State (diagram)  ................................... 339
Error Recognition Mode ........................................... 325
Filter-Mask Truth (table)  .......................................... 330
Functional Modes  .................................................... 325
Mode 0 (Legacy Mode) .................................... 325
Mode 1 (Enhanced Legacy Mode)  .................. 325
Mode 2 (Enhanced FIFO Mode) ...................... 326
Information Processing Time (IPT) .......................... 335
Lengthening a Bit Period  ......................................... 337
Listen Only Mode ..................................................... 325
Loopback Mode  ....................................................... 325
Message Acceptance Filters and Masks  ......... 302, 330
Message Acceptance Mask 
and Filter Operation ......................................... 331
Message Reception ................................................. 329
Enhanced FIFO Mode  ..................................... 330
Priority ............................................................. 329
Time-Stamping ................................................ 330
Normal Mode  ........................................................... 324
Oscillator Tolerance ................................................. 337
Overview .................................................................. 273
Phase Buffer Segments ........................................... 335
Programmable TX/RX and Auto-RTR Buffers  ......... 294
Programming Time Segments ................................. 337
Propagation Segment .............................................. 335
Sample Point  ........................................................... 335
Shortening a Bit Period ............................................ 337
Synchronization ....................................................... 336
Hard ................................................................. 336
Resynchronization ........................................... 336
Rules ............................................................... 336
Synchronization Segment ........................................ 335
Time Quanta ............................................................ 335
Values for ICODE (table) ......................................... 340
ECCP1
Capture and Compare Modes  ................................. 174
Standard PWM Mode  .............................................. 174
Effect on Standard PIC Instructions ........................... 91, 408
Effects of Power Managed Modes on 
Various Clock Sources  .............................................. 31
Electrical Characteristics  ................................................. 415
Enhanced Capture/Compare/PWM (ECCP1) .................. 173
Capture Mode. 
See
 Capture (ECCP1 Module).
Outputs and Configuration ....................................... 174
Pin Configurations for ECCP1 ................................. 174
PWM Mode. 
See
 PWM (ECCP1 Module).
Timer Resources  ............................................................. 174
Enhanced PWM Mode.
 See
 PWM (ECCP1 Module). 
Enhanced Universal Synchronous Receiver Transmitter 
(EUSART). 
See 
EUSART.

PIC18F2585/2680/4585/4680
DS39625C-page 468 Preliminary © 2007 Microchip Technology Inc.
Equations
A/D
Calculating the Minimum Required 
Acquisition Time  ......................................252
A/D Acquisition Time ................................................ 252
A/D Minimum Charging Time  ...................................252
Errata ................................................................................... 5
Error Recognition Mode  ................................................... 324
EUSART
Asynchronous Mode  ................................................ 236
Associated Registers, Receive  ........................ 239
Associated Registers, Transmit  ....................... 237
Auto-Wake-up on Sync Break ..........................240
Break Character Sequence .............................. 241
Receiver ........................................................... 238
Setting up 9-Bit Mode with 
Address Detect  ........................................238
Transmitter ....................................................... 236
Baud Rate Generator (BRG)
Associated Registers  ....................................... 231
Auto-Baud Rate Detect  ....................................234
Baud Rate Error, Calculating  ........................... 231
Baud Rates, Asynchronous Modes .................. 232
High Baud Rate Select (BRGH Bit) .................. 231
Operation in Power Managed Mode  ................ 231
Sampling .......................................................... 231
Synchronous Master Mode  ...................................... 242
Associated Registers, Receive  ........................ 244
Associated Registers, Transmit  ....................... 243
Reception ......................................................... 244
Transmission ....................................................242
Synchronous Slave Mode  ........................................ 245
Associated Registers, Receive  ........................ 246
Associated Registers, Transmit  ............... 245, 271
Reception ......................................................... 246
Transmission ....................................................245
Extended Instruction Set
ADDFSR ..................................................................404
ADDULNK ................................................................ 404
CALLW ..................................................................... 405
MOVSF ....................................................................405
MOVSS ....................................................................406
PUSHL ..................................................................... 406
SUBFSR .................................................................. 407
SUBULNK ................................................................ 407
External Clock Input  ........................................................... 24
F
Fail-Safe Clock Monitor ............................................ 343, 355
Interrupts in Power Managed Modes  ....................... 356
POR or Wake-up from Sleep  ................................... 356
WDT During Oscillator Failure  ................................. 355
Fast Register Stack ............................................................ 64
Firmware Instructions ....................................................... 361
Flash Program Memory ......................................................95
Associated Registers  ...............................................103
Control Registers  .......................................................96
EECON1 and EECON2  ..................................... 96
TABLAT (Table Latch) Register ......................... 98
TBLPTR (Table Pointer) Register  ...................... 98
Erase Sequence  ...................................................... 100
Erasing ..................................................................... 100
Operation During Code-Protect  ............................... 103
Reading ...................................................................... 99
Table Pointer
Boundaries Based on Operation  ....................... 98
Table Pointer Boundaries  .......................................... 98
Table Reads and Table Writes  .................................. 95
Write Sequence  ....................................................... 101
Writing To  ................................................................ 101
Protection Against Spurious Writes  ................. 103
Unexpected Termination  ................................. 103
Write Verify  ...................................................... 103
FSCM. 
See
 Fail-Safe Clock Monitor.
G
GOTO .............................................................................. 382
H
Hardware Multiplier .......................................................... 111
Introduction .............................................................. 111
Operation ................................................................. 111
Performance Comparison ........................................ 111
High/Low-Voltage Detect  ................................................. 267
Characteristics ......................................................... 430
Effects of a Reset  .................................................... 271
Operation ................................................................. 269
During Sleep .................................................... 271
Start-up Time ................................................... 269
Typical Application ................................................... 270
HLVD. 
See
 High/Low-Voltage Detect. 
I
I/O Ports ........................................................................... 129
I2C Mode (MSSP)
Acknowledge Sequence Timing  .............................. 220
Baud Rate Generator  .............................................. 213
Bus Collision
During a Repeated Start Condition .................. 224
During a Stop Condition  .................................. 225
Clock Arbitration  ...................................................... 214
Clock Stretching ....................................................... 206
10-Bit Slave Receive Mode (SEN = 1)  ............ 206
10-Bit Slave Transmit Mode  ............................ 206
7-Bit Slave Receive Mode (SEN = 1)  .............. 206
7-Bit Slave Transmit Mode  .............................. 206
Clock Synchronization and the CKP bit 
(SEN = 1) ......................................................... 207
Effect of a Reset  ...................................................... 221
General Call Address Support  ................................. 210
I2C Clock Rate w/BRG ............................................. 213
Master Mode ............................................................ 211
Operation ......................................................... 212
Reception ........................................................ 217
Repeated Start Condition Timing  .................... 216
Start Condition ................................................. 215
Transmission ................................................... 217
Transmit Sequence  ......................................... 212
Multi-Master Communication, Bus Collision 
and Arbitration  ................................................. 221
Multi-Master Mode ................................................... 221
Operation ................................................................. 200
Read/Write Bit Information (R/W Bit) ............... 200, 201
Registers ................................................................. 196
Serial Clock (RC3/SCK/SCL) ................................... 201
Slave Mode .............................................................. 200
Addressing ....................................................... 200
Reception ........................................................ 201
Transmission ................................................... 201

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 469
PIC18F2585/2680/4585/4680
Sleep Operation  ....................................................... 221
Stop Condition Timing .............................................. 220
ID Locations  ............................................................. 343, 360
INCF ................................................................................. 382
INCFSZ ............................................................................ 383
In-Circuit Debugger .......................................................... 360
In-Circuit Serial Programming (ICSP)  ...................... 343, 360
Indexed Literal Offset Addressing Mode  .......................... 408
and Standard PIC18 Instructions  ............................. 408
Indexed Literal Offset Mode  ......................................... 91, 93
Indirect Addressing  ............................................................ 89
INFSNZ ............................................................................ 383
Initialization Conditions for all Registers  ...................... 49–60
Instruction Cycle  ................................................................ 65
Clocking Scheme  ....................................................... 65
Instruction Flow/Pipelining  ................................................. 65
Instruction Set  .................................................................. 361
ADDLW .................................................................... 367
ADDWF .................................................................... 367
ADDWF (Indexed Literal Offset mode)  .................... 409
ADDWFC ................................................................. 368
ANDLW .................................................................... 368
ANDWF .................................................................... 369
BC ............................................................................ 369
BCF .......................................................................... 370
BN ............................................................................ 370
BNC ......................................................................... 371
BNN ......................................................................... 371
BNOV ....................................................................... 372
BNZ .......................................................................... 372
BOV ......................................................................... 375
BRA .......................................................................... 373
BSF .......................................................................... 373
BSF (Indexed Literal Offset mode)  .......................... 409
BTFSC ..................................................................... 374
BTFSS ..................................................................... 374
BTG .......................................................................... 375
BZ ............................................................................ 376
CALL ........................................................................ 376
CLRF ........................................................................ 377
CLRWDT .................................................................. 377
COMF ...................................................................... 378
CPFSEQ .................................................................. 378
CPFSGT .................................................................. 379
CPFSLT ................................................................... 379
DAW ......................................................................... 380
DCFSNZ .................................................................. 381
DECF ....................................................................... 380
DECFSZ ................................................................... 381
Extended Instructions  .............................................. 403
and Using MPLAB Tools .................................. 410
Considerations when Enabling  ........................ 408
Syntax .............................................................. 403
General Format ........................................................ 363
GOTO ...................................................................... 382
INCF ......................................................................... 382
INCFSZ .................................................................... 383
INFSNZ .................................................................... 383
IORLW ..................................................................... 384
IORWF ..................................................................... 384
LFSR ........................................................................ 385
MOVF ....................................................................... 385
MOVFF .................................................................... 386
MOVLB .................................................................... 386
MOVLW ................................................................... 387
MOVWF ................................................................... 387
MULLW .................................................................... 388
MULWF ................................................................... 388
NEGF ....................................................................... 389
NOP ......................................................................... 389
POP ......................................................................... 390
PUSH ....................................................................... 390
RCALL ..................................................................... 391
RESET ..................................................................... 391
RETFIE .................................................................... 392
RETLW .................................................................... 392
RETURN .................................................................. 393
RLCF ....................................................................... 393
RLNCF ..................................................................... 394
RRCF ....................................................................... 394
RRNCF .................................................................... 395
SETF ....................................................................... 395
SETF (Indexed Literal Offset mode) ........................ 409
SLEEP ..................................................................... 396
Standard Instructions ............................................... 361
SUBFWB ................................................................. 396
SUBLW .................................................................... 397
SUBWF .................................................................... 397
SUBWFB ................................................................. 398
SWAPF .................................................................... 398
TBLRD ..................................................................... 399
TBLWT .................................................................... 400
TSTFSZ ................................................................... 401
XORLW ................................................................... 401
XORWF ................................................................... 402
Summary Table  ....................................................... 364
INTCON Register
RBIF Bit  ................................................................... 132
INTCON Registers ........................................................... 115
Inter-Integrated Circuit. 
See
 I2C.
Internal Oscillator Block ..................................................... 26
Adjustment ................................................................. 26
INTIO Modes  ............................................................. 26
INTOSC Output Frequency  ....................................... 26
OSCTUNE Register ................................................... 26
Internal RC Oscillator
Use with WDT .......................................................... 352
Internet Address  .............................................................. 476
Interrupt Sources  ............................................................. 343
A/D Conversion Complete  ....................................... 251
Capture Complete (CCP1)  ...................................... 165
Compare Complete (CCP1)  .................................... 167
ECAN Module .......................................................... 339
Interrupt-on-Change (RB7:RB4)  .............................. 132
INTn Pin ................................................................... 128
PORTB, Interrupt-on-Change .................................. 128
TMR0 ....................................................................... 128
TMR0 Overflow ........................................................ 149
TMR2 to PR2 Match (PWM) ............................ 169, 175
TMR3 Overflow ........................................ 151, 159, 161
Interrupts ......................................................................... 113
Logic (diagram) ........................................................ 114
Interrupts, Flag Bits
Interrupt-on-Change (RB7:RB4) Flag 
(RBIF Bit) ......................................................... 132
INTOSC Frequency Drift .................................................... 26
INTOSC, INTRC. 
See
 Internal Oscillator Block.
IORLW ............................................................................. 384
IORWF ............................................................................. 384
IPR Registers ................................................................... 124

PIC18F2585/2680/4585/4680
DS39625C-page 470 Preliminary © 2007 Microchip Technology Inc.
L
LFSR ................................................................................385
Listen Only Mode  ............................................................. 324
Loopback Mode ................................................................ 324
Low-Voltage ICSP Programming 
See
 Single-Supply 
ICSP Programming.
M
Master Clear Reset (MCLR) ............................................... 43
Master Synchronous Serial Port (MSSP).
 See
 MSSP.
Memory Organization ......................................................... 61
Data Memory  .............................................................67
Program Memory  .......................................................61
Memory Programming Requirements  ..............................428
Microchip Internet Web Site  .............................................476
Migration from Baseline to Enhanced Devices  ................ 462
Migration from High-End to Enhanced Devices  ............... 463
Migration from Mid-Range to Enhanced Devices ............. 463
MOVF ............................................................................... 385
MOVFF .............................................................................386
MOVLB ............................................................................. 386
MOVLW ............................................................................ 387
MOVSF ............................................................................405
MOVSS ............................................................................ 406
MOVWF ........................................................................... 387
MPLAB ASM30 Assembler, Linker, Librarian  .................. 412
MPLAB ICD 2 In-Circuit Debugger ................................... 413
MPLAB ICE 2000 High-Performance 
Universal In-Circuit Emulator  ................................... 413
MPLAB Integrated Development 
Environment Software .............................................. 411
MPLAB PM3 Device Programmer .................................... 413
MPLAB REAL ICE In-Circuit Emulator System ................ 413
MPLINK Object Linker/MPLIB Object Librarian  ............... 412
MSSP
ACK Pulse ........................................................ 200, 201
Control Registers (general) ...................................... 187
I2C Mode. 
See 
I2C Mode.
Module Overview  ..................................................... 187
SPI Master/Slave Connection  .................................. 191
SPI Mode.
 See
 SPI Mode.
SSPBUF ...................................................................192
SSPSR .....................................................................192
MULLW ............................................................................ 388
MULWF ............................................................................388
N
NEGF ............................................................................... 389
NOP .................................................................................389
Normal Operation Mode ................................................... 324
O
Opcode Field Descriptions  ............................................... 362
OPTION_REG Register
PSA Bit ..................................................................... 149
T0CS Bit ................................................................... 148
T0PS2:T0PS0 Bits  ................................................... 149
T0SE Bit ................................................................... 148
Oscillator Configuration ......................................................23
EC .............................................................................. 23
ECIO ..........................................................................23
HS ..............................................................................23
HSPLL ........................................................................23
Internal Oscillator Block  ............................................. 26
INTIO1 ....................................................................... 23
INTIO2 ....................................................................... 23
LP .............................................................................. 23
RC ............................................................................. 23
RCIO .......................................................................... 23
XT .............................................................................. 23
Oscillator Selection  .......................................................... 343
Oscillator Start-up Timer (OST)  ................................... 31, 45
Oscillator Switching  ........................................................... 28
Oscillator Transitions  ......................................................... 29
Oscillator, Timer1 ............................................................. 161
Oscillator, Timer3 ..................................................... 151, 159
P
Packaging Information  ..................................................... 453
Details ...................................................................... 455
Marking .................................................................... 453
Parallel Slave Port (PSP) ......................................... 138, 144
Associated Registers ............................................... 145
CS (Chip Select) ...................................................... 144
PORTD .................................................................... 144
RD (Read Input) ....................................................... 144
Select (PSPMODE Bit)  .................................... 138, 144
WR (Write Input)  ...................................................... 144
PICSTART Plus Development Programmer .................... 414
PIE Registers ................................................................... 121
Pin Functions
MCLR/VPP/RE3 ................................................... 12, 16
OSC1/CLKI/RA7 .................................................. 12, 16
OSC2/CLKO/RA6 ................................................ 12, 16
RA0/AN0 .................................................................... 13
RA0/AN0/CVREF ........................................................ 17
RA1/AN1 .............................................................. 13, 17
RA2/AN2/VREF- ................................................... 13, 17
RA3/AN3/VREF+ .................................................. 13, 17
RA4/T0CKI .......................................................... 13, 17
RA5/AN4/SS/HLVDIN .......................................... 13, 17
RB0/INT0/AN10 ......................................................... 14
RB0/INT0/FLT0/AN10 ................................................ 18
RB1/INT1/AN8 ..................................................... 14, 18
RB2/INT2/CANTX ................................................ 14, 18
RB3/CANRX ........................................................ 14, 18
RB4/KBI0/AN9 ..................................................... 14, 18
RB5/KBI1/PGM .................................................... 14, 18
RB6/KBI2/PGC .................................................... 14, 18
RB7/KBI3/PGD .................................................... 14, 18
RC0/T1OSO/T13CKI ........................................... 15, 19
RC1/T1OSI .......................................................... 15, 19
RC2/CCP1 ........................................................... 15, 19
RC3/SCK/SCL ..................................................... 15, 19
RC4/SDI/SDA ...................................................... 15, 19
RC5/SDO ............................................................. 15, 19
RC6/TX/CK .......................................................... 15, 19
RC7/RX/DT .......................................................... 15, 19
RD0/PSP0/C1IN+ ...................................................... 20
RD1/PSP1/C1IN- ....................................................... 20
RD2/PSP2/C2IN+ ...................................................... 20
RD3/PSP3/C2IN- ....................................................... 20
RD4/PSP4/ECCP1/P1A ............................................. 20
RD5/PSP5/P1B ......................................................... 20
RD6/PSP6/P1C ......................................................... 20
RD7/PSP7/P1D ......................................................... 20
RE0/RD/AN5 .............................................................. 21
RE1/WR/AN6/C1OUT ................................................ 21
RE2/CS/AN7/C2OUT ................................................. 21
VDD ...................................................................... 15, 21
VSS ...................................................................... 15, 21

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 471
PIC18F2585/2680/4585/4680
Pinout I/O Descriptions
PIC18F2585/2680 ...................................................... 12
PIC18F4585/4680 ...................................................... 16
PIR Registers ................................................................... 118
PLL
Use with INTOSC ....................................................... 25
PLL Frequency Multiplier  ................................................... 25
HSPLL Oscillator Mode .............................................. 25
In INTOSC Modes ...................................................... 26
PLL Lock Time-out ............................................................. 45
POP ................................................................................. 390
POR. 
See
 Power-on Reset.
PORTA
Associated Registers  ............................................... 131
I/O Summary ............................................................ 130
LATA Register .......................................................... 129
PORTA Register  ...................................................... 129
TRISA Register  ........................................................ 129
PORTB
Associated Registers  ............................................... 134
I/O Summary ............................................................ 133
LATB Register .......................................................... 132
PORTB Register  ...................................................... 132
RB7:RB4 Interrupt-on-Change Flag 
(RBIF Bit)  ......................................................... 132
TRISB Register  ........................................................ 132
PORTC
Associated Registers  ............................................... 137
I/O Summary ............................................................ 136
LATC Register  ......................................................... 135
PORTC Register ...................................................... 135
RC3/SCK/SCL Pin  ................................................... 201
TRISC Register ........................................................ 135
PORTD
Associated Registers  ............................................... 140
I/O Summary ............................................................ 139
LATD Register  ......................................................... 138
Parallel Slave Port (PSP) Function  .......................... 138
PORTD Register ...................................................... 138
TRISD Register ........................................................ 138
PORTE
Associated Registers  ............................................... 143
I/O Summary ............................................................ 143
LATE Register .......................................................... 141
PORTE Register  ...................................................... 141
PSP Mode Select (PSPMODE Bit)  .......................... 138
TRISE Register  ........................................................ 141
Postscaler, WDT
Assignment (PSA Bit)  .............................................. 149
Rate Select (T0PS2:T0PS0 Bits) ............................. 149
Switching Between Timer0 and WDT  ...................... 149
Power Managed Modes  ..................................................... 33
and A/D Operation  ................................................... 254
and EUSART Operation ........................................... 231
and Multiple Sleep Commands  .................................. 34
Clock Sources ............................................................ 33
Clock Transitions and Status Indicators ..................... 34
Effects on Clock Sources ........................................... 31
Entering ...................................................................... 33
Exiting Idle and Sleep Modes  .................................... 39
by Interrupt ......................................................... 39
by Reset ............................................................. 39
by WDT Time-out ............................................... 39
Without an Oscillator Start-up Delay .................. 40
Idle Modes  ................................................................. 37
PRI_IDLE .......................................................... 38
RC_IDLE ........................................................... 39
SEC_IDLE ......................................................... 38
Run Modes  ................................................................ 34
PRI_RUN ........................................................... 34
RC_RUN ............................................................ 35
SEC_RUN ......................................................... 34
Selecting .................................................................... 33
Sleep Mode  ............................................................... 37
Summary (table)  ........................................................ 33
Power-on Reset (POR) ...................................................... 43
Oscillator Start-up Timer (OST) ................................. 45
Power-up Timer (PWRT) ........................................... 45
Time-out Sequence  ................................................... 45
Power-up Delays  ............................................................... 31
Power-up Timer (PWRT)  ............................................. 31, 45
Prescaler
Timer2 ..................................................................... 176
Prescaler, Capture ........................................................... 165
Prescaler, Timer0  ............................................................ 149
Assignment (PSA Bit)  .............................................. 149
Rate Select (T0PS2:T0PS0 Bits) ............................. 149
Switching Between Timer0 and WDT ...................... 149
Prescaler, Timer2  ............................................................ 170
PRI_IDLE Mode ................................................................. 38
PRI_RUN Mode ................................................................. 34
Program Counter  ............................................................... 62
PCL, PCH and PCU Registers  .................................. 62
PCLATH and PCLATU Registers  .............................. 62
Program Memory
and the Extended Instruction Set  .............................. 91
Code Protection ....................................................... 358
Instructions ................................................................ 66
Two-Word .......................................................... 66
Interrupt Vector .......................................................... 61
Look-up Tables .......................................................... 64
Map and Stack (diagram)  .......................................... 61
Reset Vector .............................................................. 61
Program Verification and Code Protection  ...................... 357
Associated Registers ............................................... 357
Programming, Device Instructions ................................... 361
PSP. 
See 
Parallel Slave Port.
Pulse-Width Modulation. 
See 
PWM (CCP1 Module) 
and PWM (ECCP1 Module).
PUSH ............................................................................... 390
PUSH and POP Instructions .............................................. 63
PUSHL ............................................................................. 406
PWM (CCP1 Module)  ...................................................... 169
Associated Registers ............................................... 171
Duty Cycle  ............................................................... 169
ECCPR1H:ECCPR1L Registers .............................. 169
Example Frequencies/Resolutions  .......................... 170
Period ...................................................................... 169
Setup for PWM Operation  ....................................... 170
TMR2 to PR2 Match ................................................ 169
PWM (ECCP1 Module) .................................................... 175
Associated Registers ............................................... 186
Auto-Shutdown ........................................................ 170
Direction Change in Full-Bridge 
Output Mode .................................................... 180
Duty Cycle  ............................................................... 176
ECCPR1H:ECCPR1L Registers .............................. 175
Effects of a Reset  .................................................... 185
Enhanced PWM Auto-Shutdown  ............................. 182

PIC18F2585/2680/4585/4680
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Example Frequencies/Resolutions  ..........................176
Full-Bridge Application Example  .............................. 180
Full-Bridge Mode ...................................................... 179
Half-Bridge Mode  ..................................................... 178
Half-Bridge Output Mode Applications 
Example ...........................................................178
Output Configurations  ..............................................176
Output Relationships (Active-High) ..........................177
Output Relationships (Active-Low) ...........................177
Period .......................................................................175
Programmable Dead-Band Delay  ............................ 182
Setup ........................................................................185
Start-up Considerations  ........................................... 184
TMR2 to PR2 Match  ................................................ 175
Q
Q Clock  .................................................................... 170, 176
R
RAM.
 See
 Data Memory.
RC Oscillator ......................................................................25
RCIO Oscillator Mode  ................................................25
RC_IDLE Mode  .................................................................. 39
RC_RUN Mode  ..................................................................35
RCALL .............................................................................. 391
RCON Register
Bit Status During Initialization  ....................................48
Reader Response  ............................................................ 477
Register File  ....................................................................... 69
Register File Summary ................................................. 76–86
Registers
ADCON0 (A/D Control 0)  ......................................... 247
ADCON1 (A/D Control 1)  ......................................... 248
ADCON2 (A/D Control 2)  ......................................... 249
BAUDCON (Baud Rate Control)  ..............................230
BIE0 (Buffer Interrupt Enable 0) ............................... 318
BnCON (TX/RX Buffer n Control, 
Receive Mode) ................................................. 294
BnCON (TX/RX Buffer n Control, 
Transmit Mode) ................................................ 295
BnDLC (TX/RX Buffer n Data Length Code 
in Receive Mode)  ............................................. 300
BnDLC (TX/RX Buffer n Data Length Code 
in Transmit Mode)  ............................................ 301
BnDm (TX/RX Buffer n Data Field Byte m 
in Receive Mode)  ............................................. 299
BnDm (TX/RX Buffer n Data Field Byte m 
in Transmit Mode)  ............................................ 299
BnEIDH (TX/RX Buffer n Extended Identifier, 
High Byte in Receive Mode)  ............................298
BnEIDH (TX/RX Buffer n Extended Identifier, 
High Byte in Transmit Mode)  ........................... 298
BnEIDL (TX/RX Buffer n Extended Identifier, 
Low Byte in Receive Mode)  ............................. 298
BnEIDL (TX/RX Buffer n Extended Identifier, 
Low Byte in Transmit Mode)  ............................ 299
BnSIDH (TX/RX Buffer n Standard Identifier, 
High Byte in Receive Mode)  ............................296
BnSIDH (TX/RX Buffer n Standard Identifier, 
High Byte in Transmit Mode)  ........................... 296
BnSIDL (TX/RX Buffer n Standard Identifier, 
Low Byte in Receive Mode)  ............................. 297
BnSIDL (TX/RX Buffer n Standard Identifier, 
Low Byte in Transmit Mode)  ............................ 297
BRGCON1 (Baud Rate Control 1)  ........................... 311
BRGCON2 (Baud Rate Control 2)  ........................... 312
BRGCON3 (Baud Rate Control 3)  ........................... 313
BSEL0 (Buffer Select 0) ........................................... 301
CANCON (CAN Control) .......................................... 276
CANSTAT (CAN Status) .......................................... 277
CCP1CON (Capture/Compare/PWM Control) ......... 163
CIOCON (CAN I/O Control) ..................................... 314
CMCON (Comparator Control)  ................................ 257
COMSTAT (CAN Communication Status) ............... 281
CONFIG1H (Configuration 1 High) .......................... 344
CONFIG2H (Configuration 2 High) .......................... 346
CONFIG2L (Configuration 2 Low)  ........................... 345
CONFIG3H (Configuration 3 High) .......................... 347
CONFIG4L (Configuration 4 Low)  ........................... 347
CONFIG5H (Configuration 5 High) .......................... 348
CONFIG5L (Configuration 5 Low)  ........................... 348
CONFIG6H (Configuration 6 High) .......................... 349
CONFIG6L (Configuration 6 Low)  ........................... 349
CONFIG7H (Configuration 7 High) .......................... 350
CONFIG7L (Configuration 7 Low)  ........................... 350
CVRCON (Comparator Voltage 
Reference Control)  .......................................... 263
Device ID Register 1 ................................................ 351
Device ID Register 2 ................................................ 351
ECANCON (Enhanced CAN Control)  ...................... 280
ECCP1AS (ECCP1 Auto-Shutdown Control)  .......... 183
ECCP1CON (Enhanced 
Capture/Compare/PWM Control)  .................... 173
ECCP1DEL (PWM Configuration)  ........................... 182
EECON1 (Data EEPROM Control 1) ................. 97, 106
HLVDCON (HLVD Control) ...................................... 267
INTCON (Interrupt Control) ...................................... 115
INTCON2 (Interrupt Control 2) ................................. 116
INTCON3 (Interrupt Control 3) ................................. 117
IPR1 (Peripheral Interrupt Priority 1)  ....................... 124
IPR2 (Peripheral Interrupt Priority 2)  ....................... 125
IPR3 (Peripheral Interrupt Priority 3)  ............... 126, 317
MSEL0 (Mask Select 0) ........................................... 307
MSEL1 (Mask Select 1) ........................................... 308
MSEL2 (Mask Select 2) ........................................... 309
MSEL3 (Mask Select 3) ........................................... 310
OSCCON (Oscillator Control) .................................... 30
OSCTUNE (Oscillator Tuning) ................................... 27
PIE1 (Peripheral Interrupt Enable 1) ........................ 121
PIE2 (Peripheral Interrupt Enable 2) ........................ 122
PIE3 (Peripheral Interrupt Enable 3) ................ 123, 316
PIR1 (Peripheral Interrupt 
Request (Flag) 1) ............................................. 118
PIR2 (Peripheral Interrupt 
Request (Flag) 2) ............................................. 119
PIR3 (Peripheral Interrupt 
Request (Flag) 3) ..................................... 120, 315
RCON (Reset Control) ....................................... 42, 127
RCSTA (Receive Status and Control)  ..................... 229
RXB0CON (Receive Buffer 0 Control) ..................... 287
RXB1CON (Receive Buffer 1 Control) ..................... 289
RXBnDLC (Receive Buffer n 
Data Length Code)  .......................................... 292
RXBnDm (Receive Buffer n 
Data Field Byte m) ........................................... 292
RXBnEIDH (Receive Buffer n Extended 
Identifier, High Byte)  ........................................ 291
RXBnEIDL (Receive Buffer n Extended 
Identifier, Low Byte) ......................................... 291
RXBnSIDH (Receive Buffer n Standard 
Identifier, High Byte)  ........................................ 290

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 473
PIC18F2585/2680/4585/4680
RXBnSIDL (Receive Buffer n Standard 
Identifier, Low Byte)  ......................................... 291
RXERRCNT (Receive Error Count)  ......................... 293
RXFBCONn (Receive Filter Buffer Control n) .......... 306
RXFCONn (Receive Filter Control n) ....................... 305
RXFnEIDH (Receive Acceptance Filter n 
Extended Identifier, High Byte)  ........................ 303
RXFnEIDL (Receive Acceptance Filter n 
Extended Identifier, Low Byte) ......................... 303
RXFnSIDH (Receive Acceptance Filter n 
Standard Identifier Filter, High Byte) ................ 302
RXFnSIDL (Receive Acceptance Filter n 
Standard Identifier Filter, Low Byte)  ................ 302
RXMnEIDH (Receive Acceptance Mask n 
Extended Identifier Mask, High Byte)  .............. 304
RXMnEIDL (Receive Acceptance Mask n 
Extended Identifier Mask, Low Byte)  ............... 304
RXMnSIDH (Receive Acceptance Mask n 
Standard Identifier Mask, High Byte)  ............... 303
RXMnSIDL (Receive Acceptance Mask n 
Standard Identifier Mask, Low Byte) ................ 304
SDFLC (Standard Data Bytes 
Filter Length Count)  ......................................... 305
SSPCON1 (MSSP Control 1, I2C Mode)  ................. 198
SSPCON1 (MSSP Control 1, SPI Mode) ................. 189
SSPCON2 (MSSP Control 2, I2C Mode)  ................. 199
SSPSTAT (MSSP Status, I2C Mode) ....................... 197
SSPSTAT (MSSP Status, SPI Mode)  ...................... 188
Status ......................................................................... 87
STKPTR (Stack Pointer)  ............................................ 63
T0CON (Timer0 Control) .......................................... 147
T1CON (Timer 1 Control) ......................................... 151
T2CON (Timer 2 Control) ......................................... 157
T3CON (Timer3 Control) .......................................... 159
TRISE (PORTE/PSP Control) .................................. 142
TXBIE (Transmit Buffers Interrupt Enable)  .............. 318
TXBnCON (Transmit Buffer n Control)  .................... 282
TXBnDLC (Transmit Buffer n 
Data Length Code)  .......................................... 285
TXBnDm (Transmit Buffer n 
Data Field Byte m)  ........................................... 284
TXBnEIDH (Transmit Buffer n Extended 
Identifier, High Byte)  ........................................ 283
TXBnEIDL (Transmit Buffer n Extended 
Identifier, Low Byte)  ......................................... 284
TXBnSIDH (Transmit Buffer n Standard 
Identifier, High Byte)  ........................................ 283
TXBnSIDL (Transmit Buffer n Standard 
Identifier, Low Byte)  ......................................... 283
TXERRCNT (Transmit Error Count)  ........................ 285
TXSTA (Transmit Status and Control)  ..................... 228
WDTCON (Watchdog Timer Control)  ...................... 353
RESET ............................................................................. 391
Resets ........................................................................ 41, 343
Brown-out Reset (BOR)  ........................................... 343
Oscillator Start-up Timer (OST)  ............................... 343
Power-on Reset (POR) ............................................ 343
Power-up Timer (PWRT)  ......................................... 343
RETFIE ............................................................................ 392
RETLW ............................................................................ 392
RETURN .......................................................................... 393
Return Address Stack  ........................................................ 62
and Associated Registers  .......................................... 62
Return Stack Pointer (STKPTR)  ........................................ 63
Revision History  ............................................................... 461
RLCF ............................................................................... 393
RLNCF ............................................................................. 394
RRCF ............................................................................... 394
RRNCF ............................................................................ 395
S
SCK ................................................................................. 187
SDI ................................................................................... 187
SDO ................................................................................. 187
SEC_IDLE Mode  ............................................................... 38
SEC_RUN Mode ................................................................ 34
Serial Clock, SCK  ............................................................ 187
Serial Data In (SDI) .......................................................... 187
Serial Data Out (SDO) ..................................................... 187
Serial Peripheral Interface. 
See
 SPI Mode.
SETF ............................................................................... 395
Slave Select (SS) ............................................................. 187
SLEEP ............................................................................. 396
Sleep
OSC1 and OSC2 Pin States ...................................... 31
Software Simulator (MPLAB SIM)  ................................... 412
Special Event Trigger. 
See
 Compare (ECCP1 Module).
Special Features of the CPU  ........................................... 343
Special Function Registers ................................................ 70
Map ...................................................................... 70–75
SPI Mode (MSSP)
Associated Registers ............................................... 195
Bus Mode Compatibility ........................................... 195
Effects of a Reset  .................................................... 195
Enabling SPI I/O ...................................................... 191
Master Mode ............................................................ 192
Master/Slave Connection  ........................................ 191
Operation ................................................................. 190
Operation in Power Managed Modes  ...................... 195
Serial Clock  ............................................................. 187
Serial Data In ........................................................... 187
Serial Data Out ........................................................ 187
Slave Mode .............................................................. 193
Slave Select ............................................................. 187
Slave Select Synchronization  .................................. 193
SPI Clock ................................................................. 192
Typical Connection  .................................................. 191
SS .................................................................................... 187
SSPOV ............................................................................ 217
SSPOV Status Flag  ......................................................... 217
SSPSTAT Register
R/W Bit  ............................................................ 200, 201
Stack Full/Underflow Resets .............................................. 64
Status Register  .................................................................. 87
SUBFSR .......................................................................... 407
SUBFWB ......................................................................... 396
SUBLW ............................................................................ 397
SUBULNK ........................................................................ 407
SUBWF ............................................................................ 397
SUBWFB ......................................................................... 398
SWAPF ............................................................................ 398
T
Table Pointer Operations (table) ........................................ 98
Table Reads/Table Writes  ................................................. 64
TBLRD ............................................................................. 399
TBLWT ............................................................................ 400
Time-out in Various Situations (table) ................................ 45

PIC18F2585/2680/4585/4680
DS39625C-page 474 Preliminary © 2007 Microchip Technology Inc.
Timer0 ..............................................................................147
Associated Registers  ...............................................149
Clock Source Edge Select (T0SE Bit) ...................... 148
Clock Source Select (T0CS Bit) ...............................148
Operation ................................................................. 148
Overflow Interrupt  ....................................................149
Prescaler.
 See
 Prescaler, Timer0.
Reads and Writes in 16-Bit Mode  ............................148
Timer1 ..............................................................................151
16-Bit Read/Write Mode ........................................... 153
Associated Registers  ...............................................155
Interrupt ....................................................................154
Operation ................................................................. 152
Oscillator .................................................................. 153
Layout Considerations  .....................................154
Resetting, Using a Special Event Trigger 
Output (CCP)  ...................................................154
Special Event Trigger (ECCP1)  ...............................174
Use as a Real-Time Clock  ....................................... 154
Timer2 ..............................................................................157
Associated Registers  ...............................................158
Interrupt ....................................................................158
Operation ................................................................. 157
Output ......................................................................158
PR2 Register .................................................... 169, 175
TMR2 to PR2 Match Interrupt  .......................... 169, 175
Timer3 ..............................................................................159
16-Bit Read/Write Mode ........................................... 161
Associated Registers  ...............................................161
Operation ................................................................. 160
Oscillator  .................................................. 151, 159, 161
Overflow Interrupt  .................................... 151, 159, 161
Special Event Trigger (CCP) .................................... 161
TMR3H Register  .............................................. 151, 159
TMR3L Register ............................................... 151, 159
Timing Diagrams
A/D Conversion ........................................................450
Acknowledge Sequence  .......................................... 220
Asynchronous Reception  ......................................... 239
Asynchronous Transmission  .................................... 237
Asynchronous Transmission (Back to Back)  ........... 237
Automatic Baud Rate Calculation  ............................ 235
Auto-Wake-up Bit (WUE) During 
Normal Operation .............................................240
Auto-Wake-up Bit (WUE) During Sleep  ................... 240
Baud Rate Generator with Clock Arbitration  ............ 214
BRG Overflow Sequence ......................................... 235
BRG Reset Due to SDA Arbitration During 
Start Condition  ................................................. 223
Brown-out Reset (BOR)  ...........................................436
Bus Collision During a Repeated 
Start Condition (Case 1)  .................................. 224
Bus Collision During a Repeated 
Start Condition (Case 2)  .................................. 224
Bus Collision During a Start 
Condition (SCL = 0)  ......................................... 223
Bus Collision During a Start 
Condition (SDA Only) ....................................... 222
Bus Collision During a Stop 
Condition (Case 1)  ........................................... 225
Bus Collision During a Stop 
Condition (Case 2)  ........................................... 225
Bus Collision for Transmit and Acknowledge ........... 221
Capture/Compare/PWM (CCP) ................................ 438
CLKO and I/O  .......................................................... 435
Clock Synchronization  ............................................. 207
Clock/Instruction Cycle  .............................................. 65
EUSART Synchronous Receive 
(Master/Slave) ................................................. 448
EUSART Synchronous Transmission 
(Master/Slave) ................................................. 448
Example SPI Master Mode (CKE = 0)  ..................... 440
Example SPI Master Mode (CKE = 1)  ..................... 441
Example SPI Slave Mode (CKE = 0)  ....................... 442
Example SPI Slave Mode (CKE = 1)  ....................... 443
External Clock (All Modes Except PLL)  ................... 433
Fail-Safe Clock Monitor  ........................................... 356
First Start Bit Timing  ................................................ 215
Full-Bridge PWM Output .......................................... 179
Half-Bridge PWM Output  ......................................... 178
High/Low-Voltage Detect  ......................................... 270
I2C Bus Data ............................................................ 444
I2C Bus Start/Stop Bits  ............................................ 444
I2C Master Mode (7 or 10-Bit Transmission)  ........... 218
I2C Master Mode (7-Bit Reception) .......................... 219
I2C Slave Mode (10-Bit Reception, SEN = 0)  .......... 204
I2C Slave Mode (10-Bit Reception, SEN = 1)  .......... 209
I2C Slave Mode (10-Bit Transmission)  .................... 205
I2C Slave Mode (7-Bit Reception, SEN = 0)  ............ 202
I2C Slave Mode (7-Bit Reception, SEN = 1)  ............ 208
I2C Slave Mode (7-Bit Transmission)  ...................... 203
I2C Slave Mode General Call Address 
Sequence (7 or 10-Bit Address Mode)  ............ 210
Master SSP I2C Bus Data ........................................ 446
Master SSP I2C Bus Start/Stop Bits  ........................ 446
Parallel Slave Port (PIC18F4585/4680) ................... 439
Parallel Slave Port (PSP) Read ............................... 145
Parallel Slave Port (PSP) Write  ............................... 145
PWM Auto-Shutdown (PRSEN = 0, 
Auto-Restart Disabled)  .................................... 184
PWM Auto-Shutdown (PRSEN = 1, 
Auto-Restart Enabled)  ..................................... 184
PWM Direction Change  ........................................... 181
PWM Direction Change at Near 
100% Duty Cycle  ............................................. 181
PWM Output  ............................................................ 169
Repeat Start Condition  ............................................ 216
Reset, Watchdog Timer (WDT), Oscillator 
Start-up Timer (OST) and Power-up 
Timer (PWRT)  ................................................. 436
Send Break Character Sequence ............................ 241
Slave Synchronization  ............................................. 193
Slow Rise Time (MCLR Tied to VDD, 
VDD Rise > TPWRT) ............................................ 47
SPI Mode (Master Mode) ......................................... 192
SPI Mode (Slave Mode with CKE = 0) ..................... 194
SPI Mode (Slave Mode with CKE = 1) ..................... 194
Stop Condition Receive or Transmit Mode  .............. 220
Synchronous Reception 
(Master Mode, SREN)  ..................................... 244
Synchronous Transmission  ..................................... 242
Synchronous Transmission (Through TXEN) .......... 243
Time-out Sequence on POR w/PLL Enabled 
(MCLR Tied to VDD) .......................................... 47
Time-out Sequence on Power-up 
(MCLR Not Tied to VDD), Case 1  ...................... 46
Time-out Sequence on Power-up 
(MCLR Not Tied to VDD), Case 2  ...................... 46
Time-out Sequence on Power-up 
(MCLR Tied to VDD, VDD Rise TPWRT) .............. 46

© 2007 Microchip Technology Inc. Preliminary DS39625C-page 475
PIC18F2585/2680/4585/4680
Timer0 and Timer1 External Clock  .......................... 437
Transition for Entry to Idle Mode ................................ 38
Transition for Entry to SEC_RUN Mode  .................... 35
Transition for Entry to Sleep Mode  ............................ 37
Transition for Two-speed Start-up 
(INTOSC to HSPLL)  ........................................ 354
Transition for Wake from Idle to Run Mode  ............... 38
Transition for Wake from Sleep (HSPLL) ................... 37
Transition from RC_RUN Mode to 
PRI_RUN Mode  ................................................. 36
Transition from SEC_RUN Mode to 
PRI_RUN Mode (HSPLL)  .................................. 35
Transition to RC_RUN Mode  ..................................... 36
Timing Diagrams and Specifications ................................ 433
A/D Conversion Requirements  ................................ 450
AC Characteristics
Internal RC Accuracy ....................................... 434
Capture/Compare/PWM Requirements  ................... 438
CLKO and I/O Requirements  ................................... 435
EUSART Synchronous Receive 
Requirements .................................................. 448
EUSART Synchronous Transmission 
Requirements .................................................. 448
Example SPI Mode Requirements
Master Mode, CKE = 0  .................................... 440
Master Mode, CKE = 1  .................................... 441
Slave Mode, CKE = 0  ...................................... 442
Slave Mode, CKE = 1  ...................................... 443
External Clock Requirements  .................................. 433
High/Low-Voltage Detect Characteristics  ................ 430
I2C Bus Data Requirements (Slave Mode)  .............. 445
Master SSP I2C Bus Data Requirements  ................ 447
Master SSP I2C Bus Start/Stop Bits 
Requirements .................................................. 446
Parallel Slave Port Requirements 
(PIC18F4585/4680) ......................................... 439
PLL Clock ................................................................. 434
Reset, Watchdog Timer, Oscillator Start-up 
Timer, Power-up Timer and Brown-out 
Reset Requirements  ........................................ 436
Timer0 and Timer1 External Clock 
Requirements .................................................. 437
Top-of-Stack Access .......................................................... 62
TRISE Register
PSPMODE Bit  ......................................................... 138
TSTFSZ ........................................................................... 401
Two-Speed Start-up ................................................. 343, 354
Two-Word Instructions
Example Cases  ......................................................... 66
TXSTA Register
BRGH Bit ................................................................. 231
V
Voltage Reference Specifications .................................... 429
W
Watchdog Timer (WDT) ........................................... 343, 352
Associated Registers ............................................... 353
Control Register ....................................................... 352
During Oscillator Failure  .......................................... 355
Programming Considerations  .................................. 352
WCOL ...................................................... 215, 216, 217, 220
WCOL Status Flag ................................... 215, 216, 217, 220
WWW Address  ................................................................ 476
WWW, On-Line Support  ...................................................... 5
X
XORLW ........................................................................... 401
XORWF ........................................................................... 402

PIC18F2585/2680/4585/4680

NOTES:

PIC18F2585/2680/4585/4680

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PIC18F2585/2680/4585/4680

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DS39625CPIC18F2585/2680/4585/4680

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PIC18F2585/2680/4585/4680

PIC18F2585/2680/4585/4680 PRODUCT IDENTIFICATION SYSTEM

To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.

PART NO. X/XX XXX

PatternPackageTemperature

Range

Device

Device PIC18F2585/2680(1), PIC18F4585/4680(1),

PIC18F2585/2680T(2), PIC18F4585/4680T(2);

VDD range 4.2V to 5.5V

PIC18LF2585/2680(1), PIC18LF4585/4680(1),

PIC18LF2585/2680T(2), PIC18LF4585/4680T(2);

VDD range 2.0V to 5.5V

Temperature Range I = -40°C to +85°C (Industrial)

E= -40°C to +125°C (Extended)

Package PT = TQFP (Thin Quad Flatpack)

SO = SOIC

SP = Skinny Plastic DIP

P=PDIP

ML = QFN

Pattern QTP, SQTP, Code or Special Requirements

(blank otherwise)

Examples:

a) PIC18LF4680-I/P 301 = Industrial temp., PDIP

package, Extended VDD limits, QTP pattern

#301.

b) PIC18LF2585-I/SO = Industrial temp., SOIC

package, Extended VDD limits.

c) PIC18F4585-I/P = Industrial temp., PDIP

package, normal VDD limits.

Note 1: F = Standard Voltage Range

LF = Wide Voltage Range

2: T = in tape and reel PLCC and TQFP

packages only.

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Fax: 81-45-471-6122

Korea - Gumi

Tel: 82-54-473-4301

Fax: 82-54-473-4302

Korea - Seoul

Tel: 82-2-554-7200

Fax: 82-2-558-5932 or

82-2-558-5934

Malaysia - Penang

Tel: 60-4-646-8870

Fax: 60-4-646-5086

Philippines - Manila

Tel: 63-2-634-9065

Fax: 63-2-634-9069

Singapore

Tel: 65-6334-8870

Fax: 65-6334-8850

Taiwan - Hsin Chu

Tel: 886-3-572-9526

Fax: 886-3-572-6459

Taiwan - Kaohsiung

Tel: 886-7-536-4818

Fax: 886-7-536-4803

Taiwan - Taipei

Tel: 886-2-2500-6610

Fax: 886-2-2508-0102

Thailand - Bangkok

Tel: 66-2-694-1351

Fax: 66-2-694-1350

EUROPE

Austria - Wels

Tel: 43-7242-2244-39

Fax: 43-7242-2244-393

Denmark - Copenhagen

Tel: 45-4450-2828

Fax: 45-4485-2829

France - Paris

Tel: 33-1-69-53-63-20

Fax: 33-1-69-30-90-79

Germany - Munich

Tel: 49-89-627-144-0

Fax: 49-89-627-144-44

Italy - Milan

Tel: 39-0331-742611

Fax: 39-0331-466781

Netherlands - Drunen

Tel: 31-416-690399

Fax: 31-416-690340

Spain - Madrid

Tel: 34-91-708-08-90

Fax: 34-91-708-08-91

UK - Wokingham

Tel: 44-118-921-5869

Fax: 44-118-921-5820

WORLDWIDE SALES AND SERVICE

12/08/06