PIC16F684T-I/SL - MICROCHIP

PIC16F684

Data Sheet

14-Pin, Flash-Based 8-Bit

CMOS Microcontrollers

with nanoWatt Technology

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Trademarks

The Microchip name and logo, the Microchip logo, Accur on,

dsPIC, KEELOQ, KEELOQ logo, microID, MPLAB, PIC,

PICmic ro, PI C START, PRO MATE, PowerSm art , rfPIC, and

SmartShunt are registered trademark s of Microchip

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and The Embedded Control Solutions Company are

registered trademarks of Microchip Technology Incorporated

in the U.S.A.

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dsPICDEM, dsPICDEM.net, dsPICworks, ECAN,

ECONOMONITOR, FanSense, FlexROM, fuzzyLAB,

In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi,

MPASM, MPLAB Certified logo, MPLIB, MPLINK, PICkit,

PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal,

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Printed on recycled paper.

Note the following details of the code protection feature on Microchip devices:

• Microchip products meet the specification contained in their particular Microchip Data Sheet.

• Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the

intended manner and under normal conditions.

• There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our

knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data

Sheets. Most likely, the person doing so is engaged in theft of intellectual property.

• Microchip is willing to work with the customer who is concerned about the integrit y of their code.

• Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not

mean that we are guaranteeing the product as “unbreakable.”

Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our

products. Attempts to break Microchip’s code protection feature may be a violat ion of the Digital Millennium Copyright Act. If suc h a c t s

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Microchip received ISO/TS-16949:2002 certification for its worldwide

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Company’s quality system processes and procedures are for its PIC®

MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial

EEPROMs, microperipherals, nonvolatile memory and analog

products. In addition, Microchip’s quality system for the design and

manufacture of development systems is ISO 9001:2000 certified.

PIC16F684

High-Performance RISC CPU:

• Only 35 instructions to learn:

- All single-cycle instructions except branches

• Operati ng spe ed:

- DC – 20 MHz oscillator/clock input

- DC – 200 ns instruction cycle

• Interrupt capability

• 8-level deep hardware stack

• Direct, Indirect and Relative Addressing modes

Special Microcontroller Features:

• Precision Internal Oscillator:

- Factory calibrated to ±1%, typical

- Software selectable frequency range of

8 MHz to 125 kHz

- Software tunable

- Two-Speed Start-up mode

- Crystal fail detect for critical applications

- Clock mode switching during operation for

power saving s

• Software Selectable 31 kHz Internal Oscillator

• Power-Saving Sleep mode

• Wide operating voltage range (2.0V-5.5V)

• Industri al and Extended Tempe rature range

• Power-on Reset (POR)

• Power-up Timer (PWRT) and Oscillator Start-up

Timer (OST)

• Brown-out Reset (BOR) with software contro l

option

• Enhanced low-current Watchdog Timer (WDT)

with on-chip oscillator (software selectable

nominal 268 seco nds wit h full pres caler) with

software enable

• Multiplexed Master Clear with pull-up/input pin

• Programmable code protection

• High Endurance Flash/EEPROM cell:

- 100,000 writ e Flash endurance

- 1,000,000 write EEPROM endurance

- Flash/Data EEPROM retention: > 40 years

Low-Power Features:

• Standby Current:

- 50 nA @ 2.0V, typical

• Operating Current:

-11μA @ 32 kHz, 2.0V, typical

-220μA @ 4 MHz, 2.0V, typical

• Watchdog Timer Current:

-1μA @ 2.0V, typical

Peripheral Feat ures:

• 12 I/O pins with individual direction contr ol:

- High current source/sink for direct LED drive

- Interrupt-on-c han ge pin

- Individually programmable weak pull-ups

- Ultra Low-Power Wake-Up (ULPWU)

• Analog Compar ator module with:

- Two ana log comparators

- Programmable on-chip voltage reference

(CVREF) module (% of VDD)

- Comparator inputs and outputs externally

accessible

• A/D Converter:

- 10-bit resolution and 8 channels

• Timer0: 8-bit timer/counter with 8-bit

progra mmab le pres caler

• Enhanced Timer1:

- 16-bit timer/counter with prescaler

- External Timer1 Gate (c ou nt enab le)

- Option to use OSC1 and OSC2 in LP mode

as Timer1 oscillator if INTOSC mode

selected

• Timer2: 8-bit timer/counter with 8-bit period

• Enhanced Capture, Compare, PWM module:

- 16-bit Capture, max resolution 12.5 ns

- Compare, max resolution 200 ns

- 10-bit PWM with 1, 2 or 4 output channels,

programmable “dead time”, max frequency

20 kHz

• In-Circuit Serial ProgrammingTM (ICSPTM) via two

pins

Device

Program

Memory Dat a Memory I/O 10-bit A/D

(ch) Comparators Timers

8/16-bit

Flash

(words) SRAM

(bytes) EEPROM

(bytes)

PIC16F684 2048 128 256 12 8 2 2/1

14-Pin Flash-Based, 8-Bit CMOS Microcontrollers with nanoWatt Technology

PIC16F684

14-Pin Diagram (PDIP, SOIC, TSSOP)

TABLE 1: DUAL IN-LINE PIN SUMMARY

I/O Pin Analog Comparators Timer CCP Interrupts Pull-ups Basic

RA0 13 AN0 C1IN+ — — IOC YICSPDAT/ULPWU

RA1 12 AN1/VREF C1IN- — — IOC Y ICSPCLK

RA2 11 AN2 C1OUT T0CKI —INT/IOC Y —

RA3(1) 4— — — — IOCY

(2) MCLR/VPP

RA4 3AN3 —T1G —IOC YOSC2/CLKOUT

RA5 2 — — T1CKI — IOC Y OSC1/CLKIN

RC0 10 AN4 C2IN+ — — — — —

RC1 9 AN5 C2IN- — — — — —

RC2 8AN6 — — P1D — — —

RC3 7 AN7 — — P1C — — —

RC4 6 — C2OUT —P1B — — —

RC5 5 — — — CCP1/P1A — — —

— 1 — — — — — — VDD

—14 — — — — — — VSS

Note 1: Input only.

2: Only when pin is configured for external MCLR.

VDD

RA5/T1CKI/OSC1/CLKIN

RA4/AN3/T1G/OSC2/CLKOUT

RA3/MCLR/VPP

RC5/CCP1/P1A

RC4/C2OUT/P1B

RC3/AN7/P1C

VSS

RA0/AN0/C1IN+/ICSPDAT/ULPWU

RA1/AN1/C1IN-/VREF/ICSPCLK

RA2/AN2/T0CKI/INT/C1OUT

RC0/AN4/C2IN+

RC1/AN5/C2IN-

RC2/AN6/P1D

PIC16F684

16-Pin Diagram (QFN)

TABLE 2: QFN PIN SUMMARY

I/O Pin Analog Comparators Timers CCP Interrupts Pull-ups Basic

RA0 12 AN0 C1IN+ — — IOC YICSPDAT/ULPWU

RA1 11 AN1/VREF C1IN- — — IOC Y ICSPCLK

RA2 10 AN2 C1OUT T0CKI —INT/IOC Y —

RA3(1) 3— — — — IOCY

(2) MCLR/VPP

RA4 2AN3 —T1G —IOC YOSC2/CLKOUT

RA5 1 — — T1CKI — IOC Y OSC1/CLKIN

RC0 9AN4 C2IN+ — — — — —

RC1 8 AN5 C2IN- — — — — —

RC2 7AN6 — — P1D — — —

RC3 6 AN7 — — P1C — — —

RC4 5 — C2OUT —P1B — — —

RC5 4 — — — CCP1/P1A — — —

—16 — — — — — — VDD

—13 — — — — — — VSS

Note 1: Input only.

2: Only when pin is configured for external MCLR.

PIC16F684

RA5/T1CKI/OSC1/CLKIN

RA4/AN3/T1G/OSC2/CLKOUT

RA3/MCLR/VPP

RC5/CCP1/P1A

VDD

VSS

RA0/AN0/C1IN+/ICSPDAT/ULPWU

RA1/AN1/C1IN-/VREF/ICSPCLK

RA2/AN2/T0CKI/INT/C1OUT

RC0/AN4/C2IN+

RC4/C2OUT/P1B

RC3/AN7/P1C

RC2/AN6/P1D

RC1/AN5/C2IN-

PIC16F684

Table of Contents

1.0 Device Overview .......................................................................................................................................................................... 5

2.0 Memory O rganization................................................................................................................................................................... 7

3.0 Oscillator Module (With Fail-Safe Clock Monitor)....................................................................................................................... 19

4.0 I/O Ports . ........................... ........................... ........................... ............................ ....................................................................... 31

5.0 Timer0 Module ........................................................................................................................................................................... 43

6.0 Timer1 Module with Gate Control............................................................................................................................................... 47

7.0 Timer2 Module ........................................................................................................................................................................... 53

8.0 Comparator Module..................... ......... .. .... .... .. ......... .. .... .... .. ......... .... .. .... .... ....... .... .. .... .... ......................................................... 55

9.0 Analog-to-Digital Converter (AD C) Module ................................................................................................................................ 65

10.0 Data EEPROM Mem o ry............................... ..................... ........................... .............................................................................. 75

11.0 Enhanc ed Capture/Com pare/PW M (With Auto-Shutdown and Dead Band) Module................................................................. 79

12.0 Specia l Features of the CPU. ........................... ..................... ............................ ................... ...................................................... 97

13.0 Instruction Set Summary.......................................................................................................................................................... 115

14.0 Development Support............................................................................................................................................................... 125

15.0 Electrical Specifications ............................................................................................................................................................ 129

16.0 DC and AC Characteristics Graphs and Tables..................................... .... .. ......... .... .... .... ....... .... .... ........................................ 151

17.0 Packagin g In fo r mation................. ............................ ..................... ..................... ....................................................................... 173

Appendix A: Data Sheet Revision History........ .... .... .... ......... .... .... .... ......... .... .... .... ......... .... .... .. ......................................................... 179

Appendix B: Migrating from other PIC® Devices................................................. ........... .... .... .... ......... .............................................. 179

Index .................................................................................................................................................................................................. 181

The Micro chip Web Site.................. .................................. ........................... ...................................................................................... 187

Customer Change Notification Service ........................ ............... ...... ............. ...... ............... ...... ......................................................... 187

Customer Support.......... ............. ...... .... ............. ...... .... ............. ...... ............. ...... .... ............................................................................ 187

Reader Response.............................................................................................................................................................................. 188

Product Identification System............................................................................................................................................................. 189

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Customer Noti fic atio n Syst em

PIC16F684

1.0 DEVICE OVERVIEW

The PIC16F684 is covered by this data sheet. It is

available in 14-pin PDIP, SOIC, TSSOP and 16-pin

QFN packages. Figure 1-1 shows a block diagram of

the PIC16F684 device. Table 1-1 shows the pinout

description.

FIGURE 1-1: PIC16F684 BLOCK DIAGRAM

Flash

Program

Memory

13 Data Bus 8

Program

Bus

Instruction Reg

Program Counter

RAM

File

Registers

Direct Addr 7

RAM Addr 9

Addr MU X

Indirect

Addr

FSR Reg

STATUS Reg

MUX

ALU

W Reg

Instruction

Decode &

Control

Timing

Generation

OSC1/CLKIN

OSC2/CLKOUT

PORTA

8-Level Stack 128 Bytes

2k X 14

(13-Bit)

Power-up

Timer

Oscillator

Start-up Timer

Power-on

Reset

Watchdog

Timer

MCLR VSS

Brown-out

Reset

Timer0 Timer1

Data

EEPROM

256 Bytes

EEDATA

EEADDR

RA0

RA1

RA2

RA3

RA4

RA5

2 Analog Comparators

Analog-To-Digital Converter

AN0 AN1 AN2 AN3 C1IN- C1IN+ C1OUT

T0CKI

INT

T1CKI

Configuration

Internal

Oscillator

VREF

and Reference

T1G

PORTC

RC0

RC1

RC2

RC3

RC4

RC5

AN4 AN5 AN6 AN7

VDD

Timer2

C2IN- C2IN+ C2OUT

ECCP

Block CCP1/P1A P1B P1C P1D

PIC16F684

TABLE 1-1: PIC16F684 PINOUT DESCRIPTION

Name Function Input

Type Output

Type Description

RA0/AN0/C1IN+/ICSPDAT/ULPWU RA0 TTL CMOS PORTA I/O with prog. pull-up and interrupt-on-change

AN0 AN — A/ D Channel 0 input

C1IN+ AN — Comparator 1 non-inverting input

ICSPDAT TTL CMOS Serial Progra mm ing Data I/O

ULPWU AN — Ultra Low-Power Wake-Up input

RA1/AN1/C1IN-/VREF/ICSPCLK RA1 TTL CMOS PORTA I/O with prog. pull-up and interrupt-on-change

AN1 AN — A/ D Channel 1 input

C1IN- AN — Comparator 1 inverting input

VREF AN — External Voltage Reference for A/D

ICSPCLK ST — Serial Programming Clock

RA2/AN2/T0CKI/IN T/C1OU T RA2 ST CMOS PORTA I/O with prog. pull-up and interrupt-on-change

AN2 AN — A/ D Channel 2 input

T0CKI ST — Timer0 clock input

INT S T — External Interrupt

C1OUT — CMOS Comparator 1 output

RA3/MCLR/VPP RA3 TTL — PORTA input with interrupt-on-change

MCLR ST — Master Clear w/internal pull-up

VPP HV — Programming voltage

RA4/AN3/T1G/OSC2/CLKOUT RA4 TTL CMOS PORTA I/O with prog. pull-up and interrupt-on-change

AN3 AN — A/ D Channel 3 input

T1G ST — Timer1 gate (count enable)

OSC2 — XTAL Crystal/Resonator

CLKOUT — CMOS FOSC/4 output

RA5/T1CKI/OS C1/CLKIN RA5 TTL C MOS PO RTA I/O with prog. pull-up and interrupt-on-change

T1CKI ST — Timer1 clock

OSC1 XTAL — Crystal/Resonator

CLKIN ST — External clock input/RC oscillator connection

RC0/AN4/C2IN+ RC0 TTL CMOS POR TC I/O

AN4 AN — A/ D Channel 4 input

C2IN+ AN — Comparator 2 non-inverting input

RC1/AN5/C2IN- RC1 TTL CMOS POR TC I/O

AN5 AN — A/ D Channel 5 input

C2IN- AN — Comparator 2 inverting input

RC2/AN6/P1D RC2 TTL CMOS PORTC I/O

AN6 AN — A/ D Channel 6 input

P1D — CMOS PWM output

RC3/AN7/P1C RC3 TTL CMOS PORTC I/O

AN7 AN — A/ D Channel 7 input

P1C — CMOS PWM output

RC4/C2OUT/P1B RC4 TTL CMOS PORTC I/O

C2OUT — CMOS Comparator 2 output

P1B — CMOS PWM output

RC5/CCP1/P1A RC5 TTL CMOS POR TC I/O

CCP1 ST CMOS Capture input/Compare output

P1A — CMOS PWM output

VDD VDD Power — Positive supply

VSS VSS Power — Ground reference

Legend: AN = Analog input or output CMOS= CMOS compatible input or output HV = High Voltage

ST = Schmitt Trigger input with CMOS levels TTL = T TL com patible input XTAL = Crystal

PIC16F684

2.0 MEMORY ORGANIZATION

2.1 Program Memory Organization

The PIC16F684 has a 13-bit program counter capable

of addre ssing an 8k x 14 pro gram memo ry spac e. Only

the first 2k x 14 (0000h-07FFh) for the PIC16F684 is

physically implemented. Accessing a location above

these boundaries will cause a wrap around within the

first 2k x 14 space. The Reset vector is at 0000h and

the interrupt vector is at 0004h (see Figure 2-1).

FIGURE 2-1: PROGRAM MEMORY MAP

AND STACK FOR THE

PIC16F684

2.2 Data Memory Organiza tion

The data memo ry (see Figure 2-2) is partitioned into two

banks, which contain the General Purpose Registers

(GPR) and the Special Function Registers (SFR). The

Special Function Registers are located in the first 32

locations of each bank. Register locations 20h-7Fh in

Bank 0 and A0h-BFh in Bank 1 are General Purpose

Registers, implemented as static RAM. Register

locations F0h-FFh in Bank 1 point to addresses 70h-7Fh

in Bank 0. All other RAM is unimplemented and returns

‘0’ when read. The RP0 bit of the STA TUS register is the

bank select bit.

RP0

0→Bank 0 is selected

1→Bank 1 is selected

PC<12:0>

0000h

0004h

0005h

07FFh

0800h

1FFFh

Stack Level 1

Stack Level 8

Reset V ector

Interrupt Vector

On-chip Program

Memory

CALL, RETURN

RETFIE, RETLW

Stack Level 2

Wraps to 0000h-07FFh

Note: The IRP and RP1 bits of the STATUS

maint ained as ‘0’s.

PIC16F684

2.2. 1 GENERAL PURPOSE REGISTER

FILE

The register file is organized as 128 x 8 in the

PIC16F684. Each register is accessed, either directly

or indirectly, through the File Select Register (FSR)

(see Section 2.4 “Indirect Addressing, INDF and

FSR Registers” ).

2.2.2 SPECIAL FUNCTION REGISTERS

The Special Function Registers are registers used by

the CPU and peripheral functions for controlling the

desired operation of the device (see Table 2-1). These

registers are static RAM.

The special registers can be classified into two sets:

core and peripheral. The Special Function Registers

associated with the “core” are described in this section.

Those related to the operation of the peripheral features

are described in the section of that peripheral feature.

FIGURE 2-2: DATA MEMORY MAP OF

THE PIC16F 68 4

Indirect Addr.(1)

TMR0

PCL

STATUS

FSR

PORTA

PCLATH

INTCON

PIR1

TMR1L

TMR1H

T1CON

00h

01h

02h

03h

04h

05h

06h

07h

08h

09h

0Ah

0Bh

0Ch

0Dh

0Eh

0Fh

10h

11h

12h

13h

14h

15h

16h

17h

18h

19h

1Ah

1Bh

1Ch

1Dh

1Eh

1Fh

20h

7Fh

Bank 0

Unimplemented data memory locations, read as ‘0’.

Note 1: Not a physical register .

CMCON0 VRCON

General

Purpose

Registers

96 Bytes

EEDAT

EEADR

EECON2(1)

File

Address File

Address

WPUA

IOCA

Indirect Addr.(1)

OPTION_REG

PCL

STATUS

FSR

TRISA

PCLATH

INTCON

PIE1

PCON

80h

81h

82h

83h

84h

85h

86h

87h

88h

89h

8Ah

8Bh

8Ch

8Dh

8Eh

8Fh

90h

91h

92h

93h

94h

95h

96h

97h

98h

99h

9Ah

9Bh

9Ch

9Dh

9Eh

9Fh

A0h

FFh

Bank 1

ADRESH

ADCON0

EECON1

ADRESL

ADCON1

ANSEL

TRISC

PORTC

BFh

General

Purpose

Registers

32 Bytes

Accesses 70h-7Fh F0h

TMR2

T2CON

CCPR1L

CCPR1H

CCP1CON

PWM1CON

ECCPAS

WDTCON

CMCON1

OSCCON

OSCTUNE

PR2

6Fh

© 2007 Microchip Technology Inc. DS41202F-page 9
PIC16F684
TABLE 2-1: PIC16F684 SPECIAL FUNCTION REGISTERS SUMMARY BANK 0 
Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2  Bit 1 Bit 0 Value on 
POR, BOR Page
Bank 0
00h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx 19, 104
01h TMR0 Timer0 Module’s Register xxxx xxxx 43, 104
02h PCL Program Counter’s (PC) Least Significant Byte 0000 0000 19, 104
03h STATUS IRP(1) RP1(1) RP0 TO PD ZDCC0001 1xxx 13, 104
04h FSR Indirect Data Memory Address Pointer xxxx xxxx 19, 104
05h PORTA(2) —— RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 31, 104
06h —Unimplemented — —
07h PORTC(2) —— RC5 RC4 RC3 RC2 RC1 RC0 --xx 0000 40, 104
08h —Unimplemented — —
09h —Unimplemented — —
0Ah PCLATH — — — Write Buffer for  upper 5 bits of Program Counter ---0 0000 19, 104
0Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 15, 104
0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 17, 104
0Dh —Unimplemented — —
0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx 47, 104
0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx 47, 104
10h T1CON T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 50, 104
11h TMR2 Timer2 Mod ule Register 0000 0000 53, 104
12h T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 54, 104
13h CCPR1L Capture/Compare/PWM Register 1 Low Byte XXXX XXXX 80, 104
14h CCPR1H Capture/Compare/PWM Register 1 High Byte XXXX XXXX 80, 104
15h CCP1CON P1M1 P1M0 DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 0000 0000 79, 104
16h PWM1CON PRSEN PDC6 PDC5 PDC4 PDC3 PDC2 PDC1 PDC0 0000 0000 96, 104
17h ECCPAS ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1 PSSBD0 0000 0000 93, 104
18h WDTCON — — — WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN ---0 1000 111, 104
19h CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 61, 104
1Ah CMCON1 — — — — — — T1GSS C2SYNC ---- --10 62, 104
1Bh —Unimplemented — —
1Ch —Unimplemented — —
1Dh —Unimplemented — —
1Eh ADRESH Most Significant 8 bits of the left shifted A/D result or 2 bits of right shifted result  xxxx xxxx 71, 104
1Fh ADCON0 ADFM VCFG — CHS2 CHS1 CHS0 GO/DONE ADON 00-0 0000 70, 104
Legend: – = Unimpl em ent ed locat io ns rea d as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented
Note 1: IRP and RP1 bits are reserved, always maintain these bits clear.
2: Port pins with analog functions controlled by the ANSEL register will read ‘0’ immediately after a Reset even though the data latches are 
either undefined (POR) or unchanged (other Resets).

PIC16F684
DS41202F-page 10 © 2007 Microchip Technology Inc.
TABLE 2-2: PIC16F684 SPECIAL FUNCTION REGISTERS SUMMARY BANK 1
Addr Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2  Bit 1 Bit 0 Value  on 
POR, BOR Page
Bank 1
80h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx 19, 104
81h OPTION_REG RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 14, 104
82h PCL Program Counter’s (PC) Least Significant Byte 0000 0000 19, 104
83h STATUS IRP(1) RP1(1) RP0 TO PD ZDCC0001 1xxx 13, 104
84h FSR Indirect Data Memory  Address Pointer xxxx xxxx 19, 104
85h TRISA —— TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 31, 104
86h —Unimplemented ——
87h TRISC —— TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 40, 104
88h —Unimplemented — —
89h —Unimplemented — —
8Ah PCLATH — — — Write Buffer for upper 5 bits of Program Counter ---0 0000 19, 104
8Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 15, 104
8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 16, 104
8Dh —Unimplemented — —
8Eh PCON —— ULPWUE SBOREN ——PORBOR--01 --qq 18, 104
8Fh OSCCON — IRCF2 IRCF1 IRCF0 OSTS(2) HTS LTS SCS -110 x000 20, 104
90h OSCTUNE — — — TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 24, 105
91h ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 32, 105
92h PR2 Timer2 Module Period Register 1111 1111 53, 105
93h —Unimplemented ——
94h —Unimplemented ——
95h WPUA(3) —— WPUA5 WPUA4 — WPUA2 WPUA1 WPUA0 --11 -111 33, 105
96h IOCA —— IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0 --00 0000 33, 105
97h —Unimplemented ——
98h —Unimplemented ——
99h VRCON VREN —VRR— VR3 VR2 VR1 VR0 0-0- 0000 63, 105
9Ah EEDAT EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0 0000 0000 75, 105
9Bh EEADR EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0 0000 0000 75, 105
9Ch EECON1 — — — — WRERR WREN WR RD ---- x000 76, 105
9Dh E ECON2 EEPROM Control Register 2 (not a physical register) ---- ---- 76, 105
9Eh ADRESL Least Significant 2 bits of the left shifted result or 8 bits of the right shifted result xxxx xxxx 71, 105
9Fh ADCON1 — ADCS2 ADCS1 ADCS0 ————-000 ---- 70, 105
Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented
Note 1: IRP and RP1 bits are reserved, always maintain these bits clear.
2: OSTS bit of the OSCCON register reset to ‘0’ with Dual Speed Start-up and LP, HS or XT selected as the oscillator.
3: RA3 pull-up is enabled when MCLRE is ‘1’ in the Configuration Word register.

PIC16F684

2.2.2.1 STATUS Register

The STATUS regi ste r, shown i n Re gis ter 2-1, contains :

• the arithm etic status of the ALU

• the Reset status

• the bank select bits for data memory (SRAM)

The STATUS register can be the destination for any

instruction, like any other register. If the STATUS

the Z, DC or C bits, then the write to these three bits is

disabl ed. These bit s are set or clea red according to the

device logic. Furthermore, the TO and PD bits are not

writable. Therefore, the result of an instruction with the

STATUS register as destination may be different than

intended.

For exam ple, CLRF STATUS, will clear the upper three

bits and set the Z bit. This leaves the STATUS register

as ‘000u u1uu’ (where u = unchanged).

It is recommended, therefore, that only BCF, BSF,

SWAPF and MOVWF instructions are used to alter the

STATUS register, because these instructions do not

affect any Status bits. For other instructions not affect-

ing any Status b it s , s ee Se ction 13.0 “Instruction Set

Summary”.

Note 1: Bits IRP and R P1 of th e STATUS register

are not used by the PIC16F684 and

should be maintained as clear. Use of

these b its is n ot reco mmen ded, s ince this

may affect upward compatibility with

future products.

2: The C and DC bits operate as a Borrow

and Digit Borrow out bit, respectively, in

subtraction. See the SUBLW and SUBWF

instructions for examples.

Reserved Reserved R/W-0 R-1 R-1 R/W-x R/W-x R/W-x

IRP RP1 RP0 TO PD ZDCC

bit 7 bit 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

bit 7 IRP: This bit is reserved and should be maintained as ‘0’

bit 6 RP1: This bit is reserved and should be maintained as ‘0’

bit 5 RP0: Register Bank Select bit (used for direct addressing)

1 = Bank 1 (80h – FFh)

0 = Bank 0 (00h – 7Fh)

bit 4 TO: Time-out bit

1 = After power-up, CLRWDT instruction or SLEEP instruction

0 = A WDT time-out occurred

bit 3 PD: Power-down bit

1 = After power-up or by th e CLRWDT instruction

0 = By execution of the SLEEP instruction

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 (ADDWF, ADDLW,SUBLW,SUBWF instructions), For Borrow, the polarity is

reversed.

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

bit 0 C: Carry/Borrow bit(1) (ADDWF, ADDLW, SUBLW, 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 1: For Borrow, the polarit y is reve rse d. A sub trac tio n is exe cut ed by addi ng the two’s com ple me nt of the sec -

ond ope rand. Fo r rota te (RRF, RLF) instructi ons, t his bit is load ed wi th either th e high -order o r low-o rder bi t

of the source register.

PIC16F684

2.2.2.2 OPTION Register

The OPTION register is a readable and writab le register ,

which cont ains various c ontrol bit s to co nfigure:

• Timer0/WDT prescaler

• External R A2/INT int errupt

•Timer0

• Weak pull-ups on PORTA

Note: To achieve a 1:1 prescaler assignment for

Timer0, assign the prescaler to the WDT

by setting PSA bit to ‘1’ of the OPTION

Programmable Prescaler”.

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0

bit 7 bit 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

bit 7 RAPU: PORTA Pull-up Enable bit

1 = PORTA pull-ups are disabled

0 = PORTA pull-ups are enabled by individual PORT latch values

bit 6 INTEDG: Interrupt Edge Select bit

1 = Interrupt on rising edge of RA2/INT pin

0 = Interrupt on falling edge of RA2/INT pin

bit 5 T0CS: Timer0 Clock Sou rce Sel ect bit

1 = Transit ion on RA2/T0CKI pin

0 = Internal instruction cycle clock (FOSC/4)

bit 4 T0SE: Timer0 Source Edge Select bit

1 = Increment on high-to-low transition on RA2/T0CKI pin

0 = Increment on low-to-high transition on RA2/T0CKI pin

bit 3 PSA: Prescaler Assig nment bit

1 = Prescaler is assigned to the WDT

0 = Prescaler is assigned to the Timer0 module

bit 2-0 PS<2:0>: Prescaler Rate Select bits

000

001

010

011

100

101

110

111

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

1 : 256

1 : 1

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

BIT VALUE TIMER0 RATE WDT RATE

PIC16F684

2.2.2.3 INTCON Register

The INTCON register is a readable and writable

for TMR0 register overflow, PORTA change and

external RA2/INT pin interrupts.

Note: Interru pt flag bi ts are set when an interrupt

conditi on occ urs, regar dless o f the s tate of

its corresponding enable bit or the global

enable bit, GIE of the INTCON register.

User software should ensure the

appropriate interrupt flag bits are clear

prior to enabling an interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

GIE PEIE T0IE INTE RAIE T0IF INTF RAIF

bit 7 bit 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

bit 7 GIE: Global Interrupt Enable bit

1 = Enables all unmasked interrupts

0 = Disables all interrupts

bit 6 PEIE: Peripheral Interrupt Enable bit

1 = Enables all unmasked peripheral interrupts

0 = Disables all peripheral interrupts

bit 5 T0IE: Timer0 Ov erfl ow Interru pt Enab le bit

1 = Enables the Timer0 interrupt

0 = Disables the Timer0 interrupt

bit 4 INTE: RA2/INT External Interrupt Enable bit

1 = Enables the RA2/INT external interrupt

0 = Disables the RA2/INT external interrupt

bit 3 RAIE: PORTA Change Interrupt Enable bit(1)

1 = Enables the PORTA change interrupt

0 = Disables the PORTA change interrupt

bit 2 T0IF: Timer0 Overflow Interrupt Flag bit(2)

1 = Timer0 register has overflowed (must be cleared in software)

0 = Timer0 register did not overflow

bit 1 INTF: RA2/INT External Interrupt Flag bit

1 = The RA2/INT external interrupt occurred (must be cleared in software)

0 = The RA2/INT external interrupt did not occur

bit 0 RAIF: PORTA Change Interrupt Flag bit

1 = When at least one of the PORTA <5:0> pins changed state (must be cleared in software)

0 = None of the PORTA <5:0> pins have changed state

Note 1: IOCA register must also be enabled.

2: T0IF bit is set when TMR0 rolls over. TMR0 is unchanged on Reset and should be initialized before

clearing T0IF bit.

PIC16F684

2.2.2.4 PIE1 Register

The PIE1 register contains the peripheral interrupt

enable bits, as shown in Register 2-4.

Note: Bit PEIE of the INTCON register must be

set to enable any peripheral interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE

bit 7 bit 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

bit 7 EEIE: EE Write Complete Interrupt Enable bit

1 = Enables the EE write complete interrupt

0 = Disables the EE write complete interrupt

bit 6 ADIE: A/D Converter (ADC) Interrupt Enable bit

1 = Enables the ADC interrupt

0 = Disables the ADC interrupt

bit 5 CCP1IE: CCP1 Interrupt Enable bit

1 = Enables the CCP1 interrupt

0 = Disables the CCP1 interrupt

bit 4 C2IE: Comparator 2 Interrupt Enable bit

1 = Enables the Comparator 2 interrupt

0 = Disables the Comparator 2 interrupt

bit 3 C1IE: Comparator 1 Interrupt Enable bit

1 = Enables the Comparator 1 interrupt

0 = Disables the Comparator 1 interrupt

bit 2 OSFIE: Oscillator Fail Interrupt Enable bit

1 = Enables the oscillator fail interrupt

0 = Disables the oscillator fail inter rupt

bit 1 TMR2IE: Timer2 to PR2 Match Interrupt Enable bit

1 = Enables the Timer2 to PR2 match interrupt

0 = Disables the Timer2 to PR2 match interrupt

bit 0 TMR1IE: Timer1 Overflow Interrupt Enable bit

1 = Enables the Timer1 overflow interrupt

0 = Disables the Timer1 overflow interrupt

PIC16F684

2.2.2.5 PIR1 Register

The PIR1 register contains the peripheral interrupt flag

bits, as shown in Register 2-5.

Note: Interrupt flag bits are set when an interrupt

condition occurs, regardless of the state of

its corresponding enable bit or the global

enable bit, GIE of the INTCON register . User

software should ensure the appropriate

interrupt fl ag bits are clear prior t o enabling

an interrupt.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF

bit 7 bit 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

bit 7 EEIF: EEPROM Write Operation Interrupt Flag bit

1 = The write operation completed (must be cleared in software)

0 = The write operation has not completed or has not been started

bit 6 ADIF: A/D Interrupt Flag bit

1 = A/D conversion complete

0 = A/D conversion has not completed or has not been started

bit 5 CCP1IF: CCP1 Interrupt Flag bit

Capture mode:

1 = A TMR1 register capture occurred (must be cleared in software)

0 = No TMR1 register captu re 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 4 C2IF: Comparator 2 Interrupt Flag bit

1 = Comparator 2 output has changed (must be cleared in software)

0 = Comparator 2 output has not changed

bit 3 C1IF: Comparator 1 Interrupt Flag bit

1 = Comparator 1 output has changed (must be cleared in software)

0 = Comparator 1 output has not changed

bit 2 OSFIF: 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 1 TMR2IF: Timer2 to PR2 Match Interrupt Flag bit

1 = Timer2 to PR2 match occurred (must be cleared in software)

0 = Timer2 to PR2 match has not occurred

bit 0 TMR1IF: Timer1 Overflow Interrupt Flag bit

1 = Timer1 register overflowed (must be cleared in software)

0 = Timer1 has not overflowed

PIC16F684

2.2.2.6 PCON Register

The Power Control (PCON) register (see Table 12-2)

cont ains flag bits to differentia te betwe en a:

• Power-on Reset (POR)

• Brown-out Reset (BOR)

• Watchdog Timer Reset (WDT)

• External MCLR Reset

The PCON register also controls the Ultra Low-Power

Wake-up and software enable of the BOR.

The PCON register bits are shown in Register 2-6.

U-0 U-0 R/W-0 R/W-1 U-0 U-0 R/W-0 R/W-x

—— ULPWUE SBOREN ——PORBOR

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5 ULPWUE: Ultra Low-Power Wake-Up Enable bit

1 = Ultra Low-Power Wake-up enabled

0 = Ultra Low-Power Wake-up disabled

bit 4 SBOREN: Software BOR Enable bit(1)

1 = BOR enabled

0 = BOR disabled

bit 3-2 Unimplemented: Read as ‘0’

bit 1 POR: Power-on Reset Status bit

1 = No Power-on Reset occurred

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

bit 0 BOR: Brown- out R eset Status bit

1 = No Brown-out Reset occurred

0 = A Brown-ou t Res et o ccurre d (m us t be se t in sof tw are afte r a Power-on Reset o r Brow n- out Re set

occurs)

Note 1: BOREN<1:0> = 01 in the Configuration Word register for this bit to control the BOR.

PIC16F684

2.3 PCL and PCLATH

The Program Counte r (PC) is 13 bit s wide. The lo w byte

comes from the PCL register, which is a readable and

writable register . The high byte (PC<12:8>) is not directly

readable or writable and comes from PCLATH. On any

Reset, the PC is cleared. Figure 2-3 shows the two

situations for the loading of the PC. The upper example

in Figure 2-3 shows how the PC is loaded on a write to

PCL (PCLATH<4:0> → PCH). The lower example in

Figure 2-3 sho ws how the PC is loaded during a CALL or

GOTO instructi on (PC L ATH<4:3> → PCH).

FIGURE 2-3: LOADING OF PC IN

DIFFERENT SITUATIONS

2.3.1 MODIFYING PCL

Executing any instruction with the PCL register as the

destination simultaneously causes the Program

Counter PC<12:8> bits (PCH) to be replaced by the

content s of th e PCLATH register. This allows the entire

contents of the program counter to be changed by first

writing the desire d upper 5 bit s to the PCLA T H registe r .

Then, when the lower 8 bits are written to the PCL

to the values contained in the PCLATH register and

those being written to the PCL register.

A comput ed GOTO is a ccom pli shed by addi ng a n offset

to the program counter (ADDWF PCL). Care should be

exercised when jumping into a look-up table or

program branch table (computed GOTO) by modifying

the PCL register. Assuming that PCLATH is set to the

table start address, if the table length is greater than

255 instructions or if the lower 8 bits of the memory

address rolls over from 0xFF to 0x00 in the middle of

the table, then PCLATH must be incremented for each

address rollover that occurs between the table

beginning and the target location within the table.

For more information refer to Application Note AN556,

“Implementing a Table Read” (DS00556).

2.3.2 STACK

The PIC16F684 Family has an 8-level x 13-bit wide

hardware stack (see Figure 2-1). The stack space is

not part of either program or data space and the Stack

Pointer is not readable or writable. The PC is PUSHed

onto the stack when a CALL instruction is executed or

an interrupt causes a branch. The stack is POPed in

the event of a RETURN, RETLW or a RETFIE

instruction execution. PCLATH is not affected by a

PUSH or POP operation.

The st ack operates as a circular buf fer . This means that

after the stack has been PUSHed eight times, the ninth

push ove rwrite s the va lue tha t was s tored fro m the firs t

push. The tenth pus h ov erw ri tes the second pus h (an d

so on).

2.4 Indirect Addressing, INDF and

FSR Registers

The INDF register is no t a physical reg ister . Addr essing

the INDF register will cause indirect addressing.

Indirect addressing is possible by using the INDF register .

Any instruction using the INDF register actually accesses

data pointed to by the File Select Register (FSR).

Reading INDF itself indirectly will produce 00h. Writing to

the INDF register indirectly results in a no operation

(althou gh Status bits may be affected). An effective 9-bit

address is obtained b y conc atenatin g the 8- bit F SR and

the IRP bit of the STATUS register, as shown in

Figure 2-4.

A simple program to clear RAM location 20h-2Fh using

indirect addressing is shown in Example 2-1.

EXAMPLE 2-1: INDIRECT ADDRESSING

12 8 7 0

5PCLATH<4:0>

PCLATH

Instruction wit

ALU Result

GOTO, CALL

OPCODE <10:0

12 11 10 0

PCLATH<4:3>

PCH PCL

PCLATH

PCH PCL

PCL a

Destinatio

Note 1: There are no Status bits to indicate stack

overflow or stack underflow conditions.

2: There are no instructions/mnemonics

called PUSH or POP. These are actions

that occur from the execution of the

CALL, RETURN, RETLW and RETFIE

instructions or the vectoring to an

interr upt add ress.

MOVLW 0x20 ;initialize pointer

MOVWF FSR ;to RAM

NEXT CLRF INDF ;clear INDF register

INCF FSR, f ;inc pointer

BTFSS FSR,4 ;all done?

GOTO NEXT ;no clear next

CONTINUE ;yes continue

PIC16F684

FIGURE 2-4: DIRECT/INDIRECT ADDRESSING PIC16F684

For memory map detail, see Figure 2-2 .

Note 1: The RP1 and IRP bits are reserved; always maintain these bits clear.

Data

Memory

Indirect AddressingDirect Addressing

Bank Select Location Select

RP1(1) RP0 6 0

From Opcode IRP(1) File Select Register

Bank Select Location Select

00 01 10 11 180h

1FFh

00h

7Fh

Bank 0 Ban k 1 Bank 2 Bank 3

NOT USED

PIC16F684

3.0 OSCILLATOR MODULE (WITH

FAIL-SAFE CLOCK MONITOR)

3.1 Overview

The Oscillator module has a wide variety of clock

sources and selection features that allow it to be used

in a wide range of applications while maximizing perf or-

mance and minimizing power consumption. Figure 3-1

illustrates a block diagram of the Oscillator module.

Clock sources can be configured from external

oscilla tors, quartz crystal resonators , ceramic resonators

and Resistor-Capacitor (RC) circuits. In addition, the

system clock source can be configured from one of two

internal oscillators, with a choice of speeds selectable via

software. Addi tio nal clo ck feat ures inc lud e:

• Selectable system clock source between external

or internal via sof tware.

• Two-Speed Start-up mode, which minimizes

latency between external oscillator start-up and

code execution.

• Fail-Safe Clock Monitor (FSCM) designed to

detect a failure of the external clock source (LP,

XT, HS, EC or RC modes) and switch

automatically to the internal oscillator.

The Os cillator mod ule can be c onfigured in one of eig ht

clock modes.

1. EC – External clock with I/O on O SC2/CLKOUT.

2. LP – 32 kHz Low-Power Crystal mode.

3. XT – Medium Gain Crystal or Ceramic Resonator

Oscillator mode.

4. HS – High Gain Crystal or Ceramic Resonator

mode.

5. RC – External Resistor-Capacitor (RC) with

FOSC/4 output on OSC2/CLKOUT.

6. RCIO – External Resistor-Capacitor (RC) with

I/O on OSC2/CLKOUT.

7. INTOSC – Internal oscillator with FOSC/4 output

on OSC2 and I/O on OSC1/CLKIN.

8. INTOSCIO – Internal oscillator with I/O on

OSC1/CLKIN and OSC2/CLKOUT.

Clock Source modes are configured by the FOSC<2:0>

bits in the Configuration Word register (CONFIG). The

internal clock can be generated from two internal

oscillators. The HFINTOSC is a calibrated

high-frequency oscillator. The LFINTOSC is an

uncalibrated low-frequency oscillator.

FIGURE 3-1: PI C® MCU CLOCK SOURCE BLOCK DIAGRAM

(CP U and Peripherals)

OSC1

OSC2

Sleep

External Oscillator

LP, XT, HS, RC, RCIO, EC

System Clock

Postscaler

MUX

8 MHz

4 MHz

2 MHz

1 MHz

500 kHz

125 kHz

250 kHz

IRCF<2:0>

111

110

101

100

011

010

001

000

31 kHz

Power-up Timer (PWRT)

FOSC<2:0>

(Configuration Word Register)

SCS<0>

(OSCCON Register)

Internal Oscillator

(OSCCON Register)

Watchdog Timer (WDT)

Fail-Safe Clock Monitor (FSCM)

HFINTOSC

8 MHz

LFINTOSC

31 kHz

INTOSC

PIC16F684

3.2 Oscillator Control

The Oscillator Control (OSCCON) register (Figure 3-1)

controls the system clock and frequency selection

options. The OSCCON register contains the following

bits:

• Frequency selection bits (IRCF)

• Frequency Status bits (HTS, LTS)

• System clock control bits (OSTS, SCS)

U-0 R/W-1 R/W-1 R/W-0 R-1 R-0 R-0 R/W-0

— IRCF2 IRCF1 IRCF0 OSTS(1) HTS LTS SCS

bit 7 bit 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

bit 7 Unimplemented: Read as ‘0’

bit 6-4 IRCF<2:0>: Internal Oscillator Frequency Select bits

111 =8MHz

110 =4MHz (default)

101 =2MHz

100 =1MHz

011 =500 kHz

010 =250 kHz

001 =125 kHz

000 =31 kHz (LFINTOSC)

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

1 = Device is running from the external clock defined by FOSC<2:0> of the CONFIG register

0 = Device is running from the internal oscillator (HFINTOSC or LFINTOSC)

bit 2 HTS: HFINTOSC Status bit (High Frequency – 8 MHz to 125 kHz)

1 = HFINTOSC is stable

0 = HFINTOSC is not stable

bit 1 LTS: LFINTOSC Stable bit (Low Frequency – 31 kHz)

1 = LFINTOSC is stable

0 = LFINT OSC is not st able

bit 0 SCS: System Clock Se lect bit

1 = Internal oscillator is used for system clock

0 = Clock source defined by FOSC<2:0> of the CONFIG register

Note 1: Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe

mode is enable d.

PIC16F684

3.3 Clock Source Modes

Clock Source modes can be classified as external or

internal.

• External Clock mod es rely on e xternal circui try fo r

the clock source. Examples are: Oscillator mod-

ules (EC mode), quartz crystal resonators or

ceramic resonators (LP, XT and HS modes) and

Resistor-Capacito r (RC ) mode circuits.

• Internal clock sources are contained internally

within the Oscillator module. The Oscillator

module has two internal oscillators: the 8 MHz

High-Frequency Internal Oscillator (HFINTOSC)

and the 31 kHz Low -Frequency Internal Os cillator

(LFINTOSC).

The syste m cl oc k ca n be selected betw ee n ex tern al or

internal clock sources via the System Clock Select

(SCS) bit of the OSCCON register. See Section 3.6

“Clock Switching” for additional information.

3.4 External Clock Modes

3.4.1 OSCILLATOR START-UP TIMER (OST)

If the Oscillator module is configured for LP, XT or HS

modes, the Oscillator Start-up Timer (OST) counts

1024 oscillations from OSC1. This occurs following a

Power-on Reset (POR) and when the Power-up Timer

(PWRT) has expired (if configured), or a wake-up from

Sleep. During this time, the program counter does not

increment and program execution is suspended. The

OST ensures that the oscillator circuit, using a quartz

cryst al res onator o r ce ramic res onator, has st arte d and

is providing a stable system clock to the Oscillator

module. When switching between clock sources, a

delay is required to allow the new clock to stabilize.

These oscillator delays are shown in Table 3-1.

In order to mi nimize laten cy between externa l oscillator

start-up and code execution, the Two-Speed Clock

Start-up mode can be selected (see Section 3.7

“Two-Speed Clock Start-up Mode”).

TABLE 3-1: OSCILLATOR DELAY EXAMPLES

3.4.2 EC MODE

The External Clock (EC) mode allows an externally

generated logic level as the system clock source. When

operating in this mode, an external clock source is

connected to the OSC1 input and the OSC2 is available

for general purpose I/O. Figure 3-2 shows the pin

connections for EC mode.

The Oscillator Start-up Timer (OST) is disabled when

EC mode is selected. Therefore, there is no delay in

operation after a Power-on Reset (POR) or wake-up

from Sleep. Because the PIC MCU design is fully st atic,

stopping the external clock input will have the effect of

halting the device while leaving all data intact. Upon

restarting the external clock, the device will resume

operation as if no time had elapsed.

FIGURE 3-2: EXTERNAL CLOCK (EC)

MODE OPERATION

Switch From Switch To Frequency Oscillator Delay

Sleep/POR LFINTOSC

HFINTOSC 31 kHz

125 kHz to 8 MHz Oscillator Warm-Up Delay (TWARM)

Sleep/POR EC, RC DC – 20 MHz 2 cycles

LFINTOSC (31 kHz) EC, RC DC – 20 MHz 1 cycle of each

Sleep/POR LP, XT, HS 32 kHz to 20 MHz 1024 Clock Cycles (OST)

LFINTOSC (31 kHz) HFINTOSC 125 kHz to 8 MHz 1 μs (approx.)

OSC1/CLKIN

OSC2/CLKOUT(1)

I/O

Clock from

Ext. System PIC® MCU

Note 1: Alternate pin functions are listed in the

Section 1.0 “Device Overview”.

PIC16F684

3.4.3 LP, XT, HS MODES

The LP, XT and HS modes support the use of quartz

crystal resonators or ceramic resonators connected to

OSC1 a nd OSC2 (Figur e 3-3). The mod e selects a low ,

medium or high gain setting of the internal

inverter-amplifier to support various resonator types

and speed.

LP Oscillator mode select s the lowest gain setting of the

internal inverter-amplifier . LP mode current consumption

is the least of the three mo des. This mode is designed to

drive only 32.768 kHz tuning-fork type crystals (watch

crystals).

XT Oscillator mode selects the intermediate gain

setting of the internal inverter-amplifier. XT mode

current c onsumption is the medium of the three mo des.

This mode is best suited to drive resonators with a

medium drive level specification.

HS Oscillator mode selects the highest gain setting of the

internal inverter-amplifier . HS mode current consumption

is the highest of the three modes. This mode is best

suited fo r reso nato rs that require a h igh driv e s ettin g.

Figure 3-3 and Figure 3-4 show typical circuits for

quartz crystal and ceramic resonators, respectively.

FIGURE 3-3: QUARTZ CRYSTAL

OPERATION (LP, XT OR

HS MODE)

FIGURE 3-4: CERAMIC RESONATOR

OPERATION

(XT OR HS MODE)

Note 1: A series resistor (RS) may be required for

quartz crystals with low drive level.

2: The value of RF varies with the Oscillator mode

selected (typically between 2 MΩ to 10 MΩ).

Quartz

RS(1)

OSC1/CLKIN

RF(2) Sleep

To Internal

Logic

PIC® MCU

Crystal

OSC2/CLKOUT

Note 1: Quartz crystal characteristics vary according

to type, package and manufacturer. The

user should consult the manufacturer data

sheet s fo r spec ifica tions and re comm ende d

application.

2: Always veri fy os ci lla tor performance ov er

the VDD and temperature range that is

expected for the application.

3: For oscillator de sign assistance, re ference

the following Microchip Applications Notes:

• AN826, “Crystal Oscillator Basics and

Crystal Selection for rfPIC® and PIC®

Devices” (DS00826)

• AN849, “Basic PIC® Oscillator Design”

(DS00849)

• AN943, “Practical PIC® Oscillator

Analysis and Design” (DS00943)

• AN949, “Making Your Oscillator Work”

(DS00949)

Note 1: A series resistor (RS) may be required for

ceramic resonators with low drive level.

2: The value of RF varies with the Oscillator mode

selected (typically between 2 MΩ to 10 M Ω).

3: An additional parallel feedback resistor (RP)

may be required for proper ceramic resonator

operation.

C2 Ceramic RS(1)

OSC1/CLKIN

RF(2) Sleep

To Internal

Logic

PIC® MCU

RP(3)

Resonator OSC2/CLKOUT

PIC16F684

3.4.4 EXTERN AL RC MODES

The external Resistor-Capacitor (RC) modes support

the use of an external RC circuit. This allows the

designer maximum flexibility in frequency choice while

keeping costs to a minimum when clock accuracy is not

required. There are two modes: RC and RCIO.

In RC mode, the RC circuit connects to OSC1.

OSC2/CLKOUT outputs the RC oscillator frequency

divide d by 4. This signal ma y b e u se d to pro vide a clock

for external circuitry, synchronization, calibration, test

or other application requirements. Figure 3-5 shows

the external RC mode connections.

FIGURE 3-5: EXTERNAL RC MODES

In RCIO mode, the RC circuit is connected to OSC1.

OSC2 becomes an additional general purpose I/O pin.

The RC oscillator frequency is a function of the supply

voltage, the resis tor (REXT) and capacitor (CEXT) values

and the operating temperature. Other factors affecting

the oscillator frequency are:

• threshold voltage variation

• component tolerances

• pack aging var iations in capacitanc e

The user also needs to take into account variation due

to tolerance of external RC components used.

3.5 Internal Clock Modes

The Oscillator module has two independent, internal

oscillators that can be configured or selected as the

system clock source.

1. The HFINTOSC (High-Frequency Internal

Oscillator) is factory calibrated and operates at

8 MHz. The f requenc y o f the HFINT O SC can be

use r-ad just ed via software using the OSCTUNE

2. The LFINTOSC (Low-Frequency Internal

Oscillator) is uncalibrated and operates at

31 kHz.

The sys tem cloc k speed can b e select ed via soft ware

using the Internal Oscillator Frequency Select bits

IRCF<2:0> of the OSCCON register.

The syste m cl oc k can be selected between ext erna l or

inte rnal cloc k sources via the S ystem Clo ck Select ion

(SCS) bit of the OSCCON register. See Section 3.6

“Clock Switching” for more information.

3.5.1 INTOSC AND INTOSCIO MODES

The INTOSC and INTOSCIO modes configure the

internal oscillators as the system clock source when

the devi ce is pr ogrammed using the o scillato r selectio n

or the FOSC<2:0> bits in the Configuration Word

In INTOSC mode, OSC 1/CLKIN is av ailable for general

purpose I/O. OSC2/CLKOUT outputs the selected

internal oscillator fre quency divide d by 4. The CLKO UT

signal may be used to provide a clock for external

circuitry, synchronization, calibration, test or other

application requirements.

In INTOSCIO mode, OSC1/CLKIN and OSC2/CLKOUT

are available for general purpose I/O.

3.5.2 HFINTOSC

The High-Fre quency Int ernal Oscil lator (HFINT OSC) is

a factory calibrated 8 MHz internal clock source. The

frequency of the HFINTOSC can be altered via

software using the OSCTUNE register (Register 3-2).

The output of the HFINTOSC connects to a postscaler

and multiplexer (see Figure 3-1). One of seven

frequencies can be selected via software using the

IRCF<2:0> bits of the OSCCON register. See

Section 3.5.4 “Frequency Select Bits (IRCF)” for

more information.

The HFINTOSC is enabled by selecting any frequency

betwee n 8 MHz and 125 kHz b y set ting th e I RCF<2:0 >

bits of the OSCCON register ≠000. Then, set the

System Clock Source (SCS) bit of the OSCCON

the IESO bit in the Configuration Word register

(CONFIG) to ‘1’.

The HF Internal Oscillator (HTS) bit of the OSCCON

OSC2/CLKOUT(1)

CEXT

REXT

PIC® MCU

OSC1/CLKIN

FOSC/4 o r

Internal

Clock

VDD

VSS

Recommended values: 10 kΩ ≤ REXT ≤ 100 kΩ, <3V

3 kΩ ≤ REXT ≤ 100 kΩ, 3-5V

CEXT > 20 pF, 2-5V

Note 1: Alternate pin functions are listed in

Section 1.0 “Device Overview”.

2: Outp ut depends upon RC or R CI O Clock

mode.

I/O(2)

PIC16F684

3.5.2.1 OSCTUNE Register

The HFINTOSC is factory calibrated but can be

adjusted in software by writing to the OSCTUNE

The default value of the OSCTUNE register is ‘0’. The

value is a 5-bit two’s complement number.

When the OSCTUNE register is modified, the

HFINTOSC frequency will begin shifting to the new

frequency. Code execution continues during this shift.

There is no indication that the shift has occurred.

OSCTUNE does not affect the LFINTOSC frequency.

Operation of features that depend on the LFINTOSC

clock source frequency, such as the Power-up Timer

(PWRT), Watchdog Timer (WDT), Fail-Safe Clock

Monitor (FSCM) and p eripherals, are not affected by the

change in frequency.

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

— — — TUN4 TUN3 TUN2 TUN1 TUN0

bit 7 bit 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

bit 7-5 Unimplemented: Read as ‘0’

bit 4-0 TUN<4:0>: Frequency Tuning bits

01111 = Maximu m frequency

01110 =

•

00001 =

00000 = Oscillator module is running at the calibrated frequency.

11111 =

•

10000 = Minimum fre quenc y

PIC16F684

3.5.3 LFINTOSC

The Low-Frequency Internal Oscillator (LFINTOSC) is

an uncalibrated 31 kHz internal clock source.

The output of the LFINTOSC connects to a postscaler

and multiplexer (see Figure 3-1). Select 31 kHz, via

software, using the IRCF<2:0> bits of the OSCCON

(IRCF)” for more information . The LFINTOSC is also the

frequency for the Power-up Timer (PWRT), Watchdog

Timer (WDT) and Fail-Safe Clock Mo nitor (FSCM).

The LFINTOSC is enabled by selecting 31 kHz

(IRCF<2:0> bit s of the OSCCON regis ter = 000) as th e

system clock source (SCS bit of the OSCCON

• Two-Speed Start-up IESO bi t of the C o nfi gura tio n

Word register = 1 and IRCF<2:0> bit s of the

OSCCON regis ter = 000

• Power-up Timer (PWRT)

• Watchdog Timer (WDT)

• Fail-Safe Clock Monitor (FSCM)

The LF Internal Oscillator (LTS) bit of the OSCCON

not.

3.5.4 FREQUENCY SELECT BITS (IRCF)

The output of the 8 MHz HFINTOSC and 31 kHz

LFINTOSC connects to a postscaler and multiplexer

(see Figure 3-1). The Internal Oscillator Frequency

Select bits IRCF<2:0> of the OSCCON register select

the frequency output of the internal oscillators. One of

eight frequencies can be selected via software:

•8 MHz

• 4 MHz (Default after Reset)

•2 MHz

•1 MHz

• 500 kHz

• 250 kHz

• 125 kHz

• 31 kHz (LFINTOSC)

3.5.5 HFINTOSC AND LFINTOSC CLOCK

SWITCH TIMING

When switching between the LFINTOSC and the

HFINTOSC, the new oscillator may already be shut

down to save power (see Figure 3-6). If th is is the cas e,

there is a delay after the IRCF<2:0> bits of the

OSCCON register are modified before the frequency

selection takes place. The LTS and HTS bits of the

OSCCON register will reflect the current active status

of the LFINTOSC and HFINTOSC oscillators. The

timing of a frequency selection is as follows:

1. IRCF<2:0> bits of the OSCCON register are

modified.

2. If the new clock is shut down, a clock start-up

delay is started.

3. Clock switch circuitry waits for a falling edge of

the current clock.

4. CLKOUT is held low and the clock switch

circuit ry w ai t s for a rising edg e in the new clock.

5. CLKOUT is now connected with the new clock.

LT S and HTS b its of th e OSCCON r egiste r are

updated as require d.

6. Clock switch is complete.

See Figure 3-1 for more details.

If the internal oscillator speed selected is between

8 MHz and 125 kHz, there is no start-up delay before

the new frequency is selected. This is because the old

and new frequencies are derived from the HFINTOSC

via the post s ca ler and multiplexe r.

Start-up delay specifications are located in the

oscillator tables of Section 15.0 “Electrical

Specifications”.

Note: Following any Reset, the IRC F<2:0> bits of

the OSCCON register are set to ‘110’ and

the frequency selection is set to 4 MHz.

The user can modify the IRCF bits to

select a different frequency.

PIC16F684

FIGURE 3-6: INTE RNAL OSCILLATOR SWITCH TIMING

HFINTOSC

LFINTOSC

IRCF <2:0>

System Clock

HFINTOSC

LFINTOSC

IRCF <2:0>

System Clock

≠ 0= 0

Start-up Time 2-cycle Sync Running

2-cycle Sync Running

HFINTOSC LFINTOSC (FSCM and WDT disabled)

HFINTOSC LFINTOSC (Either FSCM or WDT enabled)

LFINTOSC

HFINTOSC

IRCF <2:0>

System Clock

= 0 ¼ 0

Start-up Time 2-cycle Sync Running

LFINTOSC HFINTOSC LFINTOSC turns off unless WDT or FSCM is enabled

PIC16F684

3.6 Clock Switching

The system clock source can be switched between

external and internal clock sources via software using

the System Clock Select (SCS) bit of the OSCCON

3.6.1 SYSTEM CLOCK SELECT (SCS) BIT

The System Clock Select (SCS) bit of the OSCCON

the CPU and peripherals.

• When the SCS bit of the OSCCON register = 0,

the system clock source is determined by

configuration of the FOSC<2:0> bits in the

Conf iguration Word register (CON FIG).

• When the SCS bit of the OSCCON register = 1,

the system clock source is chosen by the internal

oscillator frequency selected by the IRCF<2:0>

bits of the OSCCON register. After a Re set, the

SCS bit of the OSCCON register is always

cleared.

3.6.2 OSCIL LA T OR START-UP TIME-OU T

STATUS (OSTS) BIT

The Oscillator Start-up Time-out Status (OSTS) bit of

the OSCCON register indicates whether the system

clock is running from the external clock source, as

defined by the FOSC<2:0> bits in the Configuration

Word register (CONFIG), or from the internal clock

source. In particular , OSTS indicates that the Oscillator

Start-up Timer (OST) has timed out for LP, XT or HS

modes.

3.7 Two-Speed Clock Start-up Mode

Two-Speed Start-up mode provides additional power

savings by minimizing the latency between external

oscillator start-up and code execution. In applications

that make heavy use of the Sleep mode, Two-Speed

Start-up will remove the external oscillator start-up

time from the time spent awake and can reduce the

overall power consumption of the device.

This mode allows the application to wake-up from

Sleep, perform a few instructions using the INTOSC

as the clock source and go back to Sleep without

waiting for the primary oscillator to become stable.

When the Oscillator module is configured for LP, XT or

HS modes, the Oscillator Start-up Timer (OST) is

enabled (see Section 3.4.1 “Oscillator Start-up Timer

(OST)”). The OST will suspend program execution until

1024 oscillations are counted. Two-Speed Start-up

mode minimizes the delay in code execution by

operating from the internal oscillator as the OST is

counting. When the OST count reaches 1024 and the

OSTS bit of the OSCCON register is set, program

execution switches to the ext ernal oscillator.

3.7.1 TWO-SPEED START- UP MODE

CONFIGURATION

Two-Speed Start-up mode is configured by the

following settings:

• IESO (of the Configuration Word register) = 1;

Internal/External Switchover bit (Two-Speed

St art -up mode enabled).

• SCS (of the OSCCON register) = 0.

• FOSC<2:0> bits in the Configuration Word

mode.

Two-Speed Start-up mode is entered after:

• Power-on Reset (POR) and, if enabled, after

Power-up Timer (PWRT) has expired, or

• Wake-up from Sleep.

If the external clock oscillator is configured to be

anything other than LP, XT or HS mode, then

Two-Speed Start-up is disabled. This is because the

external clock oscillator does not require any

stabilization time after POR or an exit from Sleep.

3.7. 2 TWO-SPEED START-UP

SEQUENCE

1. Wake-up from Power-on Reset or Sleep.

2. Instructions begin execution by the internal

oscillator at the frequency set in the IRCF<2:0>

bits of th e O SCCON re giste r.

3. OST enabled to count 1024 clock cycles.

4. OST timed out, wait for falling edge of the

internal oscillator.

5. OSTS is set.

6. System cloc k held lo w until the next fallin g edge

of new clock (LP, XT or HS mode).

7. System clock is switched to external clock

source.

Note: Any automatic clock switch, which may

occur from T wo-Speed S tart-up or Fail-Safe

Clock Monito r , does not update the SCS bit

of the OSCCON register. The user can

monitor the OSTS bit of the OSCCON

clock sour ce.

Note: Executing a SLEEP instruction will abort

the oscillator start-up time and will cause

the OSTS bit of the OSCCON register to

remain clear.

PIC16F684

3.7.3 CHECKING TWO-SPEED CLOCK

STATUS

Checking the state of the OSTS bit of the OSCCON

from the external clock source, as defined by the

FOSC<2:0> bits in the Configuration Word register

(CONFIG), or the internal oscillator.

FIGURE 3-7: TWO-SPEED START-UP

0 1 1022 1023

PC + 1

TOSTT

HFINTOSC

OSC1

OSC2

Program Counter

System Clock

PC - N PC

PIC16F684

3.8 Fail-Safe Clock Monitor

The Fail-Saf e Cl oc k Mo nit or (FSC M) al lows the dev ic e

to conti nue operating should th e e xte rna l os ci ll ator fail.

The FSCM can detect oscillator failure any time after

the Oscillator Start-up Timer (OST) has expired. The

FSCM is enabled by setting the FCMEN bit in the

Configuration Word register (CONFIG). The FSCM is

applicable to all external oscillator modes (LP, XT, HS,

EC, RC and RCIO).

FIGURE 3-8: FSCM BLOCK DIAGRAM

3.8.1 FAIL-SAFE DETECTION

The FSCM module detects a failed oscillator by

compari ng the extern al osci llat or to the FSCM sa mple

clock. The sample clock is generated by dividing the

LFINTOSC by 64. See Figure 3-8. Inside the fail

detector block is a latch. The external clock sets the

latch on each falling edge of the external clock. The

sample clock cle ars the latch on each rising edge of th e

sample clock. A failure is detected when an entire

half-cycle of the sample clock elapses before the

primary clock goes low.

3.8.2 FAIL-SAFE OPE RATION

When the external clock fails, the FSCM switches the

devi ce clock to an interna l clock s ource and s ets the b it

flag OSFIF of the PIR1 register. Setting this flag will

generate an interrupt if the OSFIE bit of the PIE1

steps to mitigate the problems that may arise from a

failed clock. The system clock will continue to be

sourced from the internal clock source until the device

firmware successfully restarts the external oscillator

and switches back to external operation.

The internal clock source chosen by the FSCM is

determined by the IRCF<2:0> bits of the OSCCON

configured before a failure occurs.

3.8.3 FAIL-SAFE CONDITION CLEARING

The Fail-Safe condition is cleared after a Reset,

executing a SLEEP instruction or toggling the SCS bit

of the OSCCON register. When the SCS bit is toggled,

the OST is restarted. While the OST is running, the

device co ntinue s to op erate fro m the I NT OSC selecte d

in OSCCON. When the OST times out, the Fail-Safe

condition is cleared and the device will be operating

from the ex ternal cl ock sourc e. The Fai l-Safe co nditio n

must be c le ared bef ore th e O SFIF flag can be cle are d.

3.8.4 RESET OR WAKE-UP FROM SL EEP

The FSCM is designed to detect an oscillator failure

after the Oscillator Start-up Timer (OST) has expired.

The OST is used after waking up from Sleep and after

any type of Reset. The OST is not used with the EC or

RC Clock modes so that the FSCM will be active as

soon as the Reset or wake-up has completed. When

the FSCM is enabled, the Two-Speed Start-up is also

enabled . Therefore, the device will alway s be ex ecuting

code while the OST is operating.

External

LFINTOSC ÷ 64

31 kHz

(~32 μs) 488 Hz

(~2 ms)

Clock Monitor

Latch

Clock

Failure

Detected

Oscillator

Clock

Sample Clock Note: Due to the wide range of oscillator start-up

times, the Fail-Safe circuit is not active

during oscillator start-up (i.e., after exiting

Reset or Sleep). After an appropriate

amount of time, the user should check the

OSTS bit of the OSCCON register to verify

the oscillator start-up and that the system

clock switchover has successfully

completed.

PIC16F684

FIGURE 3-9: FSCM TIMING DIAGRAM

TABLE 3-2: SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES

OSCFIF

System

Clock

Output

Sample Clock

Failure

Detected

Oscillator

Failure

Note: The system c lock is normally at a much higher frequency than the sam ple clock. The relative frequencies in

this example have been chosen for clarity.

(Q)

Test Test Test

Clock Monitor Output

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets(1)

CONFIG(2) CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 — —

OSCCON — IRCF2 IRCF1 IRCF0 OSTS HTS LTS SCS -110 x000 -110 x000

OSCTUNE ——— TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 ---u uuuu

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by oscillators.

Note 1: Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.

2: See Configuration Word register (Register 12-1) for operation of all register bits.

PIC16F684

4.0 I/O PORTS

There ar e a s man y as twelve ge neral pur pose I/O pi ns

available. Depending on which peripherals are enabled,

some or all of t he pins may not be available as general

purpose I /O. In gen eral, when a per ipheral is enabled,

the associated pin may not be used as a general

purpose I/O pin.

4.1 PORTA and the TRISA Registers

PORTA is a 6-bit wide, bidirectional port. The

corresponding data direction register is TRISA

(Register 4-2). Setting a TRISA bit (= 1) will make the

corresponding PORTA pin an input (i.e., disable the

output driver). Clearing a TRISA bit (= 0) will make the

corresponding PORT A p in an output (i.e., enables outp ut

driver and puts the contents of the output latch on the

selected pin). The exception is RA3, which is input only

and its TRIS bit will always read as ‘1’. Example 4-1

shows how to ini tial ize PO R TA.

Reading the PORTA register (Register 4-1) reads the

status of the pins, whereas writing to it will write to the

PORT latch. All write operations are read-modify-write

operations. Therefore, a write to a port implies that the

port pins are read, this value is modified and then

written to the PORT data latch. RA3 reads ‘0’ when

MCLRE = 1.

The TRISA register controls the direction of the

PORTA pins, even when they are being used a s analog

inputs. The user must ensure the bits in the TRISA

input s. I/O pin s co nfigure d as analo g inpu t alw ays rea d

‘0’.

EXAMPLE 4- 1: INITIALI ZING PORTA

Note: The ANSEL and CMCON0 registers must

be initialized to configure an analog

channel as a digital input. Pins configured

as analog inputs will read ‘0’.

BCF STATUS,RP0 ;Bank 0

CLRF PORTA ;Init PORTA

MOVLW 07h ;Set RA<2:0> to

MOVWF CMCON0 ;digital I/O

BSF STATUS,RP0 ;Bank 1

CLRF ANSEL ;digital I/O

MOVLW 0Ch ;Set RA<3:2> as inputs

MOVWF TRISA ;and set RA<5:4,1:0>

;as outputs

BCF STATUS,RP0 ;Bank 0

U-0 U-0 R/W-x R/W-0 R-x R/W-0 R/W-0 R/W-0

—— RA5 RA4 RA3 RA2 RA1 RA0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 RA<5:0>: PORTA I/O Pin bit

1 = PORTA pin is > VIH

0 = PORTA pin is < VIL

U-0 U-0 R/W-1 R/W-1 R-1 R/W-1 R/W-1 R/W-1

—— TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 TRISA<5:0>: PORTA Tri-State Control bit

1 = PORTA pin configured as an input (tri-stated)

0 = PORTA pin configured as an output

Note 1: TRISA<3> always reads ‘1’.

2: TRISA<5:4> always reads ‘1’ in XT, HS and LP OSC modes.

PIC16F684

4.2 Additional Pin Functions

Every PORTA pin on the PIC16F684 has an

interrupt-on-change option and a weak pull-up option.

RA0 has an Ultra Low-Power Wake-up optio n. The next

three sections describe these functions.

4.2.1 ANSEL REGISTER

The ANSEL register is used to configure the Input

mode of an I/O pin to analog. Setting the appropriate

ANSEL bit hi gh wil l ca us e all digi t al read s on the pi n to

be rea d as ‘0’ and allow analog functions on the pin to

operate correctly.

The state of the ANSEL bits has no affect on digital

output functions. A pin with TRIS clear and ANSEL set

will still operate as a digital output, but the Input mode

will be analog. This can cause unexpected behavior

when executing read-modify-write instructions on the

affec ted port.

4.2.2 WEAK PULL-UPS

Each of the PORTA pins, except RA3, has an

individually configurable internal weak pull-up. Control

bits WPUAx enable or disable each pull-up. Refer to

Re gi st er 4- 4. Each weak pull-up is automatic ally turne d

off when the port pin is configured as an output. The

pull-ups are disabled on a Power-on Reset by the

RAPU bit of the OPTION register). A weak pull-up is

automatically enabled for RA3 when configured as

MCLR and disabled when RA3 is an I/O. There is no

software control of the MCLR pul l-up .

4.2.3 INTERRUPT-ON-CHANGE

Each of the PORTA pins is individually configurable as

an interrupt-on-change pin. Control bits IOCAx enable

or disable the interrupt function for each pin. Refer to

Power-on Reset.

For enabled interrupt-on-change pins, the values are

comp ared with the old val ue latch ed on the la st read of

PORTA. The ‘mismatch’ outputs of the last read are

OR’d tog ether to set the PO RTA Change Inte rrupt Fla g

bit (RAIF) in the INTCON register (Register 2-3).

This interrupt can wake the device from Sleep. The

user, in the Interrupt Service Routine, clears the inter-

rupt by:

a) Any read or write of PORTA. This will end the

mismatch condition, then,

b) Clear the flag bit RAIF.

A mism at c h c ond it i on wi ll co nti n ue to s et f lag bi t RA IF.

Reading PORTA will end the mismatch condition and

allow flag bit RAIF to be cleared. The latch holding the

last read value is not affected by a MCLR nor

Brown-out Reset. After these resets, the RAIF flag will

continue to be set if a mismatch is present.

Note: If a change on the I/O pin should occur

when any PORTA operation is being

execute d, then the RAIF i nterrupt flag ma y

not get 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

ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0

bit 7 bit 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

bit 7-0 ANS<7:0>: Analog Select bits

Analog select between analog or digital function on pins AN<7:0>, respectively.

1 = Analog input. Pin is assigned as analog input(1).

0 = Digital I/O. Pin is assigned to port or special function.

Note 1: Setting a pin to an analog input automatically disables the digital input circuitry, weak pull-ups and

interrupt-on-change, if available. The corresponding TRIS bit must be set to Input mode in order to allow

external control of the voltage on the pin.

PIC16F684

U-0 U-0 R/W-1 R/W-1 U-0 R/W-1 R/W-1 R/W-1

—— WPUA5 WPUA4 — WPUA2 WPUA1 WPUA0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-4 WPUA<5:4>: Weak Pull-up Control bits

1 = Pull-up enabled

0 = Pull-up disabled

bit 3 Unimplemented: Read as ‘0’

bit 2-0 WPUA<2:0>: Weak Pull-up Control bits

1 = Pull-up enabled

0 = Pull-up disabled

Note 1: Global RAPU must be enabled for individual pull-ups to be enabled.

2: The weak pull-up device is automatically disabled if the pin is in Output mode (TRISA = 0).

3: The RA3 pull-up is enabled when configured as MCLR and disabled as an I/O in the Configuration Word.

4: WPUA<5:4> always reads ‘1’ in XT, HS and LP OSC modes.

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

—— IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 IOCA<5:0>: Interrupt-on-change PORTA Control bit

1 = Interrupt-on-change enabled

0 = Interrupt-on-change disabled

Note 1: Global Interrupt Enable (GIE) must be enabled for individual interrupts to be recognized.

2: IOCA<5:4> always reads ‘1’ in XT, HS and LP OSC modes.

PIC16F684

4.2.4 ULTRA LOW-POWER WAKE-UP

The Ultra Low-Power Wake-Up (ULPWU) on RA0

allows a slow falling voltage to generate an

interrupt-on-change on RA0 without excess current

consumption. The mode is selected by setting the

ULPWUE bit of the PCON register . This enables a sm all

current sink whic h can be used to discharge a cap acitor

on RA0.

To use this feature, the RA0 pin is first configured to output

‘1’ to charge the capacitor. Then interrupt-on-change for

RA0 is enabled, an d RA0 is configure d as an input. The

ULPWUE bit is set to begin the discharge and a SLEEP

instruction is performed. When the voltage on RA0 drops

below VIL, the device will wake-up and execute the next

instruction. If the GIE bit of the INTCON register is set, the

device will call the inter rupt service ro utine (00 04h). See

Section 4.2.3 “Interrupt-on-Change” and

Section 12.4.3 “PORTA Interrupt-on-Change” for

more information.

This feature provides a low-power technique for

periodically waking up the device from Sleep. The

time-out is dependent on the discharge time of the RC

circuit on RA0. See Example 4-2 for initializing the Ultra

Low-Power Wake-Up module.

The series resistor provides overcurrent protection for

the RA0 pin and can allow for software calibration of

the time-out (see Figure 4-1). A timer can be used to

measure the charge time and discharge time of the

capacitor. The charge time can then be adjusted to

provide the desired interrupt delay. This technique will

compen sate for the af fect s o f te mpera ture, v olt age an d

component accuracy. The Ultra Low-Power Wake-Up

peripheral can also be configured as a simple

Programmable Low Voltage Detect or temperature

sensor.

EXAMPLE 4-2: ULTRA LOW-POWER

WAKE-UP INITIALIZATION

Note: For more information, refer to AN879,

“Using the Microchip Ultra Low-Power

Wake-Up Module” Application Note

(DS00879).

BANKSEL CMCON0 ;

MOVLW H’7’ ;Turn off

MOVWF CMCON0 ;comparators

BANKSEL ANSEL ;

BCF ANSEL,0 ;RA0 to digital I/O

BCF TRISA,0 ;Output high to

BANKSEL PORTA ;

BSF PORTA,0 ;charge capacitor

CALL CapDelay ;

BANKSEL PCON ;

BSF PCON,ULPWUE ;Enable ULP Wake-up

BSF IOCA,0 ;Select RA0 IOC

BSF TRISA,0 ;RA0 to input

MOVLW B’10001000’ ;Enable interrupt

MOVWF INTCON ; and clear flag

SLEEP ;Wait for IOC

PIC16F684

4.2.5 PIN DESCRIPTIONS AND

DIAGRAMS

Each PORTA pin is multiplexed with other functions.

The pins and their combined functions are briefly

described here. For specific information about

individual functions such as the Comparator or the

ADC, refer to the appro priate sec tion in this data s heet.

4.2.5.1 RA0/AN0/C1IN+/ICSPDAT/ULPWU

Figure 4-1 shows th e diagr am f or this pi n. The RA0 pi n

is configurable to function as one of the following:

• a general pu rpose I/ O

• an analog input for the ADC

• an analog non-inverting input to the comparator

• In-Circuit Se rial Programming data

• an analog input for the Ultra Low-Power Wake-Up

4.2.5.2 RA1/AN1/C1IN-/VREF/ICSPCLK

Figur e 4-2 sh ows the di agram fo r this pi n. The RA1 pi n

is configurable to function as one of the following:

• a general purpo se I/O

• an analog input for the ADC

• an analog inverting input to the comparator

• a voltage reference input for the ADC

• In-Circuit Serial Programming clock

FIGURE 4-1: BLOCK DIAGRAM OF RA0

VDD

VSS

VDD

Weak

RD PORTA

IOCA

Interrupt-on-

To Comparator

Analog(1)

Input Mode

RAPU

Analog(1)

Input Mode

Change

IULP

WPUA

Data Bus

WPUA

PORTA

TRISA

PORTA

Note 1: Comparator mode and AN SEL determines Analog Input mode.

+VT

ULPWUE

To A/D Converter

VSS

I/O Pin

PIC16F684

FIGURE 4-2: BLOCK DIAGRAM OF RA1 4.2.5.3 RA2/AN2/T0CKI/INT/C1OUT

Figur e 4-3 sh ows the di agram fo r this pi n. The RA2 pi n

is configurable to function as one of the following:

• a general purpo se I/O

• an analog input for the ADC

• the clock inpu t for TMR0

• an external edge triggered interrupt

• a digital output from Comparato r 1

FIGURE 4-3: BLOCK DIAGRAM OF RA2

VDD

VSS

VDD

Weak

Data Bus

WPUA

RD PORTA

PORTA

TRISA

IOCA

Interrupt-on-

To Comparator

Analog(1)

Input Mode

RAPU

Analog(1)

Input Mode

Change

Note 1: Comparator mode and ANSEL determines Analog

Input mode.

To A/D Converter

I/O Pin

VDD

VSS

VDD

Weak

Analog(1)

Input Mode

Data Bus

WPUA

PORTA

TRISA

IOCA

To A/D Converter

C1OUT

Enable

To INT

To Timer0

Analog(1)

Input Mode

RAPU

RD PORTA

Interrupt-on-

Change

Note 1: Analog Input mode is generated by ANSEL.

I/O Pin

PIC16F684

4.2.5.4 RA3/MCLR/VPP

Figure 4-4 shows th e diagr am f or this pi n. The RA3 pi n

is configurable to function as one of the following:

• a general pu rpose input

• as Master Clear Reset with weak pull-up

FIGURE 4-4: BLOCK DIAGRAM OF RA3

4.2.5.5 RA4/AN3/T1G/OSC2/CLKOUT

Figur e 4-5 sh ows the di agram fo r this pi n. The RA4 pi n

is configurable to function as one of the following:

• a general purpo se I/O

• an analog input for the ADC

• a Timer1 gate (coun t enabl e)

• a cryst al/ reso nator connectio n

• a clock output

FIGURE 4-5: BLOCK DIAGRAM OF RA4

VSS

Data Bus

RD PORTA

PORTA

IOCA

Reset MCLRE

TRISA VSS

MCLRE

VDD

Weak

MCLRE

Interrupt-on-

Change

Input

VDD

VSS

VDD

Weak

Analog

Input Mode

Data Bus

WPUA

PORTA

TRISA

IOCA

FOSC/4

To A/D Converter

Oscillator

Circuit

OSC1

CLKOUT

Enable

Analog(3)

Input Mode

RAPU

RD PORTA

To T1G

INTOSC/

RC/EC(2)

CLK(1)

Modes

CLKOUT

Enable

Note 1: CLK modes are XT, HS, LP, LPTMR1 and CLKOUT

Enable.

2: With CLKOUT option.

3: Analog Input mode comes from ANSEL.

Interrupt-on-

Change

I/O Pin

PIC16F684

4.2.5.6 RA5/T1CKI/OSC1/CLKIN

Figure 4-6 shows th e diagr am f or this pin. Th e RA5 pi n

is configurable to function as one of the following:

• a general pu rpose I/ O

• a Timer1 clock input

• a crystal/resonator connection

• a clock input

FIGURE 4-6: BLOCK DIAGRAM OF RA5

VDD

VSS

VDD

Weak

Data Bus

WPUA

PORTA

TRISA

IOCA

To Timer1

INTOSC

Mode

RD PORTA

INTOSC

Mode

RAPU

OSC2

Note 1: Timer1 LP Oscillator enabled.

TMR1LPEN(1)

Interrupt-on-

Change

Oscillator

Circuit

I/O Pin

PIC16F684

TABLE 4-1: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

PCON ——ULPWUESBOREN — — POR BOR --01 --qq --0u --uu

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

IOCA —— IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0 --00 0000 --00 0000

OPTION_REG RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

PORTA —— RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 --uu uu00

TRISA —— TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111

WPUA ——WPUA5WPUA4— WPUA2 WPUA1 WPUA0 --11 -111 --11 -111

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTA.

PIC16F684

4.3 PORTC

PORTC is a general purpose I/O port consisting of 6

bidirec tional pins . The pins c an b e con figured for e ither

digital I/O or analog input to A/D Converter (ADC) or

Comparator. For specific information about individual

functio ns such a s the Enhan ced CCP or t he ADC , refer

to the appropriate section in this data sheet.

EXAMPLE 4- 3: INITIALI ZING PORTC

Note: The ANSEL and CMCON0 registers must

be initialized to configure an analog chan -

nel as a digital input. Pins configured as

analog inputs will read ‘0’.

BANKSEL PORTC ;

CLRF PORTC ;Init PORTC

MOVLW 07h ;Set RC<4,1:0> to

MOVWF CMCON0 ;digital I/O

BANKSEL ANSEL ;

CLRF ANSEL ;digital I/O

MOVLW 0Ch ;Set RC<3:2> as inputs

MOVWF TRISC ;and set RC<5:4,1:0>

;as outputs

BCF STATUS,RP0 ;Bank 0

U-0 U-0 R/W-x R/W-x R/W-0 R/W-0 R/W-0 R/W-0

—— RC5 RC4 RC3 RC2 RC1 RC0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 RC<5:0>: PORTC I/O Pin bit

1 = PORTC pin is > VIH

0 = PORTC pin is < VIL

U-0 U-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

—— TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0

bit 7 bit 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

bit 7-6 Unimplemented: Read as ‘0’

bit 5-0 TRISC<5:0>: PORTC Tri-State Control bit

1 = PORTC pin configured as an input (tri-stated)

0 = PORTC pin configured as an output

PIC16F684

4.3.1 RC0/AN4/C2IN+

The RC0 is configurable to function as one of the

following:

• a general pu rpose I/ O

• an analog input for the ADC

• an analog non-inverting input to the comparator

4.3.2 RC1/AN5/C2IN-

The RC1 is configurable to function as one of the

following:

• a general pu rpose I/ O

• an analog input for the ADC

• an analog inverting input to the comparator

FIGURE 4-7: BLOCK DIAGRAM OF RC0

AND RC1

4.3.3 RC2/AN6/P1D

The RC2 is configurable to function as one of the

following:

• a general purpo se I/O

• an analog input for the ADC

• a digita l outp ut from the Enha nc ed CCP

4.3.4 RC3/AN7/P1C

The RC3 is configurable to function as one of the

following:

• a general purpo se I/O

• an analog input for the ADC

• a digita l outp ut from the Enha nc ed CCP

FIGURE 4-8: BLOCK DIAGRAM OF RC2

AND RC3

I/O Pi

VDD

VSS

Data Bus

PORTC

TRISC

To A/D Converter

PORTC

Analog Input

Mode(1)

To Comparators

Note 1: Analog Input mode comes from ANSEL or

Comparator mode.

I/O Pin

VDD

VSS

Data Bus

PORTC

TRISC

To A/D Converter

PORTC

Analog Input

Mode(1)

CCPOUT

Enable

Note 1: Analog Input mode comes from ANSEL.

PIC16F684

4.3.5 RC4/C2OUT/P1B

The RC4 is configurable to function as one of the

following:

• a general pu rpose I/ O

• a digital output from the comparator

• a digital output from the Enhanced CCP

FIGURE 4-9: BLOCK DIAGRAM OF RC4

4.3.6 RC5/CCP1/P1A

The RC5 is configurable to function as one of the

following:

• a general purpo se I/O

• a digital input/output for the Enhanced CCP

FIGURE 4-10: BLOCK DIAGRAM OF RC5

TABLE 4-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTC

Note: Enabl ing both C2O UT and P1B wi ll cause

a confli ct on RC4 and create unpredictable

results. Therefore, if C2OUT is enabled,

the ECCP can not be used in Half-Bridge

or Full-Bridge mode and vice-versa.

I/O Pin

VDD

VSS

Data Bus

PORTC

TRISC

PORTC

Note 1: Port/Peripheral Select signals selects between

port data and peripheral output.

C2OUT EN

CCPOUT EN

C2OUT EN

C2OUT

CCPOUT EN

CCPOUT

I/O Pin

VDD

VSS

Data bus

PORTC

TRISC

To Enhanced CCP

PORTC

CCP1OUT

Enable

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

PORTC —— RC5 RC4 RC3 RC2 RC1 RC0 --xx 0000 --uu uu00

TRISC —— TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111

Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTC.

PIC16F684

5.0 TIMER0 MODULE

The Timer0 module is an 8-bit timer/counter with the

following features:

• 8-bit timer/counter register (TMR0)

• 8-bit prescaler (shared with Watchdog Timer)

• Programmable internal or external clock source

• Programmable external clock edge selection

• Inter rupt on ov erflow

Figure 5-1 is a block diagram of the Timer0 module.

5.1 Timer0 Operation

When use d as a tim er, the T imer0 modul e can be used

as either an 8-bit timer or an 8-bit counter.

5.1.1 8-BIT TIMER MODE

When used as a timer, the Timer0 module will

increment every instruction cycle (without prescaler).

Timer mode is selected by clearing the T0CS bit of the

OPTION register to ‘0’.

When TMR0 is written, the increment is inhibited for

two instruction cycles immediately following the write.

5.1.2 8-BIT COUNTER MODE

When used as a counter, the Timer0 module will

increment on every rising or falling edge of the T0CKI

pin. The incrementing edge is determined by the T0SE

bit of the OPTION register . Counter mode is selected by

setting the T0CS bit of the OPTION register to ‘1’.

FIGURE 5-1: BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER

Note: The value writ ten to the T MR0 register can

be adju sted, in order to ac count for th e two

instruction cycle delay when TMR0 is

written.

T0CKI

T0SE

TMR0

Watchdog

Timer

WDT

Time-out

PS<2:0>

WDTE

Data Bus

Set Flag bi t T0 IF

on Overflow

T0CS

Note 1: T0SE , T0CS, PSA, PS<2:0> are bits in the OPTION register.

2: SWDTEN and WDTPS<3:0> are bits in the WDTCON register.

3: WDTE bit is in the Configuration Word register.

Sync 2

cycles

8-bit

Prescaler

FOSC/4

PSA

16-bit

Prescaler 16

WDTPS<3:0>

31 kHz

INTOSC

SWDTEN 3

PIC16F684

5.1.3 SOFTWAR E PROGRAMMABLE

PRESCALER

A single software programmable prescaler is available

for use with either Timer0 or the Watchdog Timer

(WDT), but not both simultaneously. The prescaler

assignme nt is control led by the PSA bit o f the OPTI ON

must be cleared to a ‘0’.

There are 8 prescaler options for the Timer0 module

ranging from 1:2 to 1:256. The prescale values are

select able via the PS<2:0> bit s of the OPTIO N register .

In order to have a 1:1 prescaler value for the Timer0

module, the prescaler must be assigned to the WDT

module.

The prescaler is not readable or writable. When

assigned to the T im er0 module, all instructions writing to

the TMR0 register will clear the prescaler.

When the prescaler is assigned to WDT, a CLRWDT

instruction will clear the prescaler along with the WDT.

5.1.3.1 Switching Prescaler Between

Timer0 and WDT Modules

As a result of having the prescaler assigned to either

Timer0 or the WDT, it is possible to generate an

unintended device Reset when switching prescaler

values . When chan gin g th e presca le r ass ig nme nt from

Timer0 to the WDT module, the instruction sequence

shown in Example 5-1 must be executed.

EXAMPLE 5-1: CHANGING PRESCALER

(TIMER0 →WDT)

When changing the prescaler assignment from the

WDT to the Timer0 module, the following instruction

sequence must be executed (see Example 5-2).

EXAMPLE 5-2: CHANGING PRESCALER

(WDT →TIMER0)

5.1.4 TIMER0 INTERRUPT

Timer0 will generate an interrupt when the TMR0

flag bit of the INTCON register is set every time the

TMR0 register overflows, regardless of whether or not

the Timer0 interrupt is enabled. The T0IF bit must be

cleared in software. The Timer0 interrupt enable is the

T0IE bit of the INTCON register.

5.1.5 USING TIMER0 WITH AN

EXTERNAL CLOCK

When Timer 0 is in Coun ter mode, t he synchronizatio n

of the T0CKI input and the Timer0 register is accom-

plished by sampling the prescaler output on the Q2 and

Q4 cycles of the internal phase clocks. Therefore, the

high and low peri od s of the ex tern al cl oc k so urc e mus t

meet the timing requirements as shown in

Section 15.0 “Electrical Specifications”.

BANKSEL TMR0 ;

CLRWDT ;Clear WDT

CLRF TMR0 ;Clear TMR0 and

; prescaler

BANKSEL OPTION_REG ;

BSF OPTION_REG,PSA ;Select WDT

CLRWDT ;

;

MOVLW b’11111000’ ;Mask prescaler

ANDWF OPTION_REG,W ; bits

IORLW b’00000101’ ;Set WDT prescaler

MOVWF OPTION_REG ; to 1:32

Note: The Timer0 interrupt cannot wake the

processor from Sleep since the timer is

frozen during Sleep.

CLRWDT ;Clear WDT and

;prescaler

BANKSEL OPTION_REG ;

MOVLW b’11110000’ ;Mask TMR0 select and

ANDWF OPTION_REG,W ; prescaler bits

IORLW b’00000011’ ;Set prescale to 1:16

MOVWF OPTION_REG ;

PIC16F684

TABLE 5-1: SUMMARY OF REGISTERS ASSOCIATED WITH TIMER0

R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1

RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0

bit 7 bit 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

bit 7 RAPU: PORTA Pull-up Enable bit

1 = PORTA pull-ups are disabled

0 = PORTA pull-ups are enabled by individual PORT latch values

bit 6 INTEDG: Interrupt Edge Select bit

1 = Interrupt on rising edge of INT pin

0 = Interrupt on falling edge of INT pin

bit 5 T0CS: TMR0 Cloc k Sourc e Sele ct bit

1 = Transit ion on T0CKI pin

0 = Internal instruction cycle clock (FOSC/4)

bit 4 T0SE: TMR0 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: Prescaler Assig nme nt bit

1 = Prescaler is assigned to the WDT

0 = Prescaler is assigned to the Timer0 module

bit 2-0 PS<2:0>: Prescaler Rate Select bits

Note 1: A dedicated 16-bit WDT postscaler is available. See Section 12.6 “Watchdog Timer (WDT)” for more

information.

000

001

010

011

100

101

110

111

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

1 : 256

1 : 1

1 : 2

1 : 4

1 : 8

1 : 16

1 : 32

1 : 64

1 : 128

BIT VALUE TMR0 RA TE WDT RA T E

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

TMR0 Timer0 Module Register xxxx xxxx uuuu uuuu

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

OPTION_REG RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

TRISA — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111

Legend: – = Un im ple me nted lo cations, read as ‘0’ , u = unchan ged , x = u nk now n . Sha ded cells are no t us ed b y t he

Timer0 module.

PIC16F684

NOTES:

PIC16F684

6.0 TIMER1 MODULE WITH GATE

CONTROL

The Timer1 module is a 16-bit timer/counter with the

following features:

• 16-bit tim er/coun ter register p air (TMR 1H:TMR 1L)

• Programmable internal or external clock source

• 3-bit prescaler

• Op tional LP oscillator

• Synchronous or asynchronous operation

• Timer1 gate (count enable) via comparator or

T1G pin

• Inter rupt on ov erflow

• Wake-up on overflow (external cloc k,

Asynchronous mode only)

• Time base for the Capture/Compare function

• Specia l Event Trigger (with ECCP)

• Comparator output synchronization to Timer1

clock

Figure 6-1 is a block diagram of the Timer1 module.

6.1 Timer1 Operation

The Timer1 module is a 16-bit incrementing counter

which is acces sed through the TMR 1H:TMR1L reg ister

pair. Writes to TMR1H or TMR1L directly update the

counter.

When us ed with an interna l clock so urce, the module i s

a time r. When used wi th an ex terna l clock sourc e, the

module can be used as either a timer or counter.

6.2 Clock Source Selection

The TMR1CS bit of the T1CON register is used to select

the clock source. When TMR1CS = 0, the clock source

is FOSC/4. When TMR1CS = 1, the clock source is

supplied exte rnally.

FIGURE 6-1: TIMER1 BLOCK DIAGRAM

Clock Source TMR1CS

FOSC/4 0

T1CKI pin 1

TMR1H TMR1L

Oscillator T1SYNC

T1CKPS<1:0>

Prescaler

1, 2, 4, 8 Synchronize

det(2)

Synchronized

clock input

Set flag bit

TMR1IF on

Overflow TMR1(1)

TMR1GE

TMR1ON

T1OSCEN

C2OUT

T1GSS

T1GINV

To C2 Comparator Module

Timer1 Clock

TMR1CS

OSC2/T1G

OSC1/T1CKI

* ST Buffer is low power type when using LP osc, or high speed type when using T1CKI.

Note 1: Timer1 register increm ents on rising edge.

2: Synchronize does not operate while in Sleep.

FOSC/4

Internal

Clock

FOSC = 100

FOSC = 000

Sleep

PIC16F684

6.2.1 INTERNAL CLOCK SOURCE

When the internal clock source is selected, the

TMR1H:TMR1L register pair will increment on multiples

of FOSC as determined by the Timer1 prescaler.

6.2.2 EXTERN AL CLOCK SOURCE

When the external clock source is selected, the Timer1

module may wo rk as a timer or a cou nter.

When counting, Timer1 is incremented on the rising

edge of the external clock input T1CKI. In addition, the

Counter mode clock can be synchronized to the

microcontroller system clock or run async hronously.

If an external clock oscillator is needed (and the

microc ontroller is using the INTOS C withou t CLKOUT),

Timer1 can use the LP oscillator as a clock source.

6.3 Timer1 Prescaler

Timer1 has four prescaler options allowing 1, 2, 4 or 8

divisions of the clock input. The T1CKPS bits of the

T1CON register control the prescale counter. The

prescale counter is not directly readable or writable;

however , the prescaler counter is cleared upon a write to

TMR1H or TMR1L.

6.4 Timer1 Oscillator

A low-power 32.768 kHz crystal oscillator is built-in

between pins OSC1 (input) and OSC2 (amplifier

output). The oscillator is enabled by setting the

T1OSCEN control bit of the T1CON register. The

oscillator will continue to run during Sleep.

The Timer1 oscillator is shared with the system LP

oscillator. Thus, Timer1 can use this mode only when

the primary system clock is derived from the internal

oscillator or when the oscillator is in the LP mode. The

user must provide a software time delay to ensure

proper oscillator start-up.

TRISA5 and TRISA4 bits are set when the Timer1

oscill ato r is enabled. RA5 an d R A4 b it s rea d as ‘0’ and

TRISA5 and TRISA4 bits read as ‘1’.

6.5 Timer1 Operation in

Asynchronous Counter Mode

If control bit T1SYNC of the T1CON register is set, the

external clock input is not synchronized. The timer

increments asynchronously to the internal phase

clocks. If external clock source is selected then the

timer will continue to run during Sleep and can

generate an interru pt on overflow, which will w ake-up

the processor. However, special precautions in

software are needed to read/write the timer (see

Section 6.5.1 “Reading and Writing Timer1 in

Asynchronous Counter Mode”).

6.5.1 READING AND WRITING TIMER1 IN

ASYNCHRONOUS COUNTER

MODE

Reading TMR1H or TMR1L while the timer is running

from an e xternal asyn chronous cl ock will ens ure a valid

read (taken care of in hardware). However, the user

should keep i n mind that rea ding t he 16-bi t time r in tw o

8-bit values itself, poses certain problems, since the

timer may overflow or carry out of TMR1L to TMR1H

between the reads.

For writes , it is re commend ed that th e user s imply sto p

the timer and write the desired values. A write

conte ntion may occ ur by writin g to th e time r regi sters,

while the register is incrementing. This may pro duce an

unpredictable value in the TMR1H:TMR1L register pair .

Note: In Counter mode, a falling edge must be

registered by the counter prior to the first

incrementing rising edge after any one or

more of the following conditions:

• Timer1 ena ble d after POR rese t

• Write to TMR1H or TMR1L

• Timer1 is disab led

• Timer1 is disabled (TMR1ON 0) when

T1CKI is high then Timer1 is enabled

(TMR1ON=1) when T1CKI is low.

See Figure 6-2

Note: The oscillator requires a start-up and

stabilization time before use. Thus,

T1OSCEN should be set and a suitable

delay observed prior to enabling Timer1.

Note: When switching from synchronous to

asynchronous operation, it is possible to

skip an increment. When switching from

asynchronous to synchronous operation,

it is possible to produce an additional

increment.

© 2007 Microchip Technology Inc. DS41202F-page 49
PIC16F684
6.6 Timer1 Gate
Timer1 gate source is software configurable to be the
T1G pin or the output of Comparator 2. This allows the
device to directly time external events using T1G or
analog events using Comparator 2. See the CMCON1
register (Register 8-2) for selecting the Timer1 gate
source. This feature can simplify the software for a
Delta-Sigma A/D converter and many other applications.
For more information on Delta-Sigma A/D converters,
see the Microchip web site (w ww.microchip.com). 
Timer1 gate can be inverted using the T1GINV bit of
the T1CON  register, whether it ori ginates from the T1G
pin or Comparator 2 output. This configures Timer1 to
measure either the active-high or active-low time
between events.
6.7 Timer1 Interrupt
The Timer1 register pair (TMR1H:TMR1L) increments
to FFFFh and rolls over to 0000h. When Timer1 rolls
over, the Ti mer1 in terrupt fl ag bit of th e PIR1 regis ter is
set. To enable the interrupt on rollover, you must set
these bits:
• TMR 1ON bit or the T1CON register
• TMR1IE bit of the PIE1 register
• PEIE bit of the INTCON register
• GIE bit of the INTCON register
The interrupt is cleared by clearing the TMR1IF bit in
the Interrupt Service Routine.
6.8 Timer1 Operation During Sleep
Timer1 can only operate during Sleep when setup in
Asynch ronous Counter mode. In this mode, an external
crystal or clock source can be used to increment the
counter. To set up the timer to wake the device:
• TMR1ON bit of the T1CON register must be set
• TMR1IE bit of the PIE1 register must be set
• PEIE bit of the INTCON register must be set
• T1SYNC bit of the T1CON register
• TMR1CS bit of the T1CON register
• T1OSCEN bit of the T1CON register (can be set)
The device will wake-up on an overflow and execute
the next instruction. If the GIE bit of the INTCON
register is set, the device will call the Interrupt Service
Routine (0004h).
6.9 ECCP Capture/Comp are Time Base
The ECCP module uses the TMR1H:TMR1L register
pair as the time base when operating in Capture or
Compare mode.
In Capture mode, the value in the TMR1H:TMR1L
register pair is copied into the CCPR1H:CCPR1L
register pair on a configured event. 
In Compare mode,  an event is triggered wh en the value
CCPR1H:CCPR1L register pair matches the value in
the TMR1H:TMR1L register pair. This event can be a
Special E vent Trigger.
For more information, see Section 11.0 “Enhanced
Capture/Compare/PWM (With Auto-Shutdown and
Dead Band) Module”.
6.10 ECCP Special Event Trigger
When the ECCP is configured to trigger a special
event, the trigger will clear the TMR1H:TMR1L register
pair. This special event does not cause a Timer1
interrupt. The ECCP module may still be configured to
generate a ECCP interrupt.
In this mode of operation, the CCPR1H:CCPR1L
register pair ef fe cti ve ly b ec ome s th e period registe r for
Timer1.
Timer1 should be synchronized to the FOSC to utilize
the Special Event Trigger. Asynchronous operation of
Timer1 can cause a Special Event Trigger to be
missed.
In the eve nt that a wri te to TMR1H or TM R1L coinci des
with a Special Event Trigger from the ECCP, the write
will take precedence.
For more information, see Section 11.2.4 “Special
Event Trigger”.
6.11 Comparator Synchronization
The same clock us ed to increment Timer1 can also be
used to synchronize the comparator output. This
feature is enabled in the Comparator module.
When using the comparator for Timer1 gate, the
comparator output should be synchronized to Timer1.
This ensures Timer1 does not miss an increment if the
comp ara tor changes.
For more information, see Section 8.9 “Synchronizing
Comparator C2 Output to Timer1”.
Note: TMR1GE bit of the T1CON register must
be set to us e ei the r  T1G  or C2OU T as th e
Timer1 gate source. See the CMCON1
register (Register 8-2) for more informa-
tion on selecting the Timer1 gate source.
Note: The T MR1H:TTMR1L  register p air and the
TMR1IF bit should be cleared before
enabling interrupts.

PIC16F684

FIGURE 6-2: TIMER1 INCREMENTING EDGE

6.12 Timer1 Control Register

The Timer1 Control register (T1CON), shown in

various features of the Timer1 module.

T1CKI = 1

when TMR1

Enabled

T1CKI = 0

when TMR1

Enabled

Note 1: Arrows ind icate counter increments.

2: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge of the clock

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

T1GINV(1) TMR1GE(2) T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON

bit 7 bit 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

bit 7 T1GINV: Timer1 Gate Invert bit(1)

1 = Timer1 gate is active high (Timer1 counts when gate is high)

0 = Timer1 gate is active low (Timer1 counts when gate is low)

bit 6 TMR1GE: Timer1 Gate Enable bit(2)

If TMR1ON = 0:

This bit is ignored

If TMR1ON = 1:

1 = Timer1 is on if Timer1 gate is not active

0 = Timer1 is on

bit 5-4 T1CKPS<1:0>: 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: LP Osci lla tor Enab le Contro l bit

If INTOSC without CLKOUT oscillator is active:

1 = LP oscillator is enabled for Timer1 clock

0 = LP oscillator is off

Else:

This bit is ignored

PIC16F684

TABLE 6-1: SUMMARY OF REGISTERS ASSOCIATED WITH TIMER1

bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit

TMR1 CS = 1:

1 = Do not synchroniz e exte rnal cloc k inp ut

0 = Synchronize external clock input

TMR1 CS = 0:

This bit is ignored. Timer1 uses the internal clock

bit 1 TMR1CS: Timer1 Clock Sourc e Sele ct bit

1 = External clock from T1CKI pin (on the rising edge)

0 = Internal clock (FOSC/4)

bit 0 TMR1ON: Timer1 On bit

1 = Enables Timer1

0 = Stops Timer1

Note 1: T1GINV bit inverts the Timer1 gate logic, regardless of source.

2: TMR1GE bit mu st be set to use either T1G pin or C2OUT, as selected by the T1GSS bit of the CMCON1

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Va lue on

all other

Resets

CMCON1 — — — — — — T1GSS C2SYNC ---- --10 ---- --10

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

T1CON T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

Legend: x = unknown, u = unchanged, — = unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module.

PIC16F684

NOTES:

PIC16F684

7.0 TIMER2 MODULE

The Timer2 module is an eight-bit timer with the

following features:

• 8-bit timer register (TMR2)

• 8-bit period register (PR2)

• Interrupt on TMR2 match with PR2

• Software programmable prescaler (1:1, 1:4, 1:16)

• Software programmable postscaler (1:1 to 1:16)

See Figure 7-1 for a block diagram of Timer2.

7.1 Timer2 Operation

The clock input to the Timer2 module is the system

instruction clock (FOSC/4). The clock is fed into the

Timer2 prescaler, which has prescale options of 1:1,

1:4 or 1:16. The output of the prescal er is the n use d to

increm ent the TM R2 regis ter.

The val ues of T MR2 and PR2 are co nstan tly com pared

to determine when they match. TMR2 will increment

from 00h until it matches the value in PR2. When a

match occurs, two things happen:

• TMR2 is reset to 00h on the next increment cycle.

• The Timer2 postscaler is incremented

The matc h o utp ut of the Timer2/PR2 comp arator is fed

into the Timer2 postscaler. The postscaler has

post scal e options of 1 :1 to 1: 16 inclus ive. The output of

the Timer2 postscaler is used to set the TMR2IF

interrupt flag bit in the PIR1 register.

The TMR2 and PR2 registers are both fully readable

and w rita ble. O n any Rese t, the TMR2 regis ter is set to

00h and the PR2 register is set to FFh.

Timer2 is turned on by setting the TMR2ON bit in the

T2CON register to a ‘1’. Tim er2 is turned off by clearing

the TMR2ON bit to a ‘0’.

The Timer2 presc ale r is contro lle d by the T2CKPS bits

in the T2CON register. The Timer2 postscaler is

controlled by the TOUTPS bits in the T2CON register.

The prescaler and postscaler counters are cleared

when:

• A write to TMR2 occurs.

• A write to T2CON occurs.

• Any device Reset occurs (Power-on Rese t, MCLR

Reset, Wa tchdog Timer Reset, or Brown-out

Reset).

FIGURE 7-1: TIMER2 BLOCK DIAGRAM

Note: TMR2 is not cleared when T2CON is

written.

Comparator

TMR2 Sets Flag

TMR2

Output

Reset

Postscaler

Prescaler

PR2

FOSC/4

1:1 to 1:16

1:1, 1:4, 1:16

bit TMR2IF

TOUTPS<3:0>

T2CKPS<1:0>

PIC16F684

TABLE 7-1: SUMMARY OF ASSOCIATED TIMER2 REGISTERS

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

— TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0

bit 7 bit 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

bit 7 Unimplemented: Read as ‘0’

bit 6-3 TOUTPS<3:0>: Timer2 Output Postscaler Select bits

0000 = 1:1 Postscaler

0001 = 1:2 Postscaler

0010 = 1:3 Postscaler

0011 = 1:4 Postscaler

0100 = 1:5 Postscaler

0101 = 1:6 Postscaler

0110 = 1:7 Postscaler

0111 = 1:8 Postscaler

1000 = 1:9 Postscaler

1001 = 1:10 Postscaler

1010 = 1:11 Po stscaler

1011 = 1:12 Postscaler

1100 = 1:13 Postscaler

1101 = 1:14 Postscaler

1110 = 1:15 Postscaler

1111 = 1:16 Postscaler

bit 2 TMR2ON: Timer2 On bit

1 = Timer2 is on

0 = Timer2 is off

bit 1-0 T2CKPS<1:0>: Timer2 Clock Prescale Select bits

00 =Prescaler is 1

01 =Prescaler is 4

1x = Prescaler is 16

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PR2 Timer2 Module Peri od Register 1111 1111 1111 1111

TMR2 Holding Register for the 8-bit TMR2 Register 0000 0000 0000 0000

T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000

Legend: x = unknown, u = unchanged, — = unimplemented read as ‘0’. Shaded cells are not used for Timer2 module.

PIC16F684

8.0 COMPARATOR MODULE

Comparators are used to interface analog circuits to a

digital circuit by comparing two analog voltages and

providing a digital indication of their relative magnitudes.

The comparators are very useful mixed signal building

blocks because they provide analog functionality

independent of the device program execution. The

analog Comparator module includes the following

features:

• Dual comparators

• Multiple comparator configurations

• Comparator ou tput s are available internally/

externally

• Programmable output polarity

• Interrupt-on-change

• Wake-up from Sleep

• Timer1 gate (co unt ena ble)

• Output synchronization to Timer1 clock input

• Programmable volt age reference

8.1 Comparator Overview

A comparator is shown in Figure 8-1 along with the

relationship between the analog input levels and the

digital output. When the analog voltage at VIN+ is less

than the analog voltage at VIN-, the output of the

comparator is a digital low level. When the analog

voltage at VIN+ is greater than the analog voltage at

VIN-, the output of th e comp arator is a dig ita l high leve l.

FIGURE 8-1: SINGLE COMP ARATOR

This device contains two comparators as shown in

Figure 8-2 and Figure 8-3. The comparators are not

independently configurable.

Note: Only Comparator C2 can be linked to

Timer1.

–

VIN+

VIN-Output

Output

VIN+

VIN-

Note: The black areas of the output of the

comparator represents the uncertainty

due to input offsets and response time.

PIC16F684

FIGURE 8-2: COMPARATOR C1 OUTPUT BLOCK DIAGRAM

FIGURE 8-3: COMP ARATOR C2 OUTPUT BLOCK DIAGRAM

To C1OUT pin

RD CMCON0

Set C1IF bit

MULTIPLEX

Port Pins

Q3*RD CMCON0

Reset

To Data Bus

C1INV

Note 1: Q1 and Q3 are phases of the four-phase system clock (FOSC).

2: Q1 is held high during Sleep mode.

C2SYNC

To C2OUT pin

RD CMCON0

Set C 2 IF b i t

MULTIPLEX

Port Pins

Q3*RD CMCON0

Reset

To Data Bus

C2INV

Timer1

clock source(1)

To Timer1 Gate

Note 1: Comparator output is latched on falling edge of Timer1 clock source.

2: Q1 and Q3 are phases of the four-phase system clock (FOSC).

3: Q1 is held high during Sleep mode.

PIC16F684

8.1.1 ANALOG INPUT CONNECTION

CONSIDERATIONS

A simplified circuit for an analog input is shown in

Figure 8-4. Sinc e the analo g input pins share thei r con-

nection with a digital input, they have reverse biased

ESD protection 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 may occur.

A maximum source impedance of 10 kΩ is recommended

for the analog sources. Also, any external component

connected to an anal og inpu t pin, such as a capacitor or

a Zener diode, should h ave very little leakage curr ent to

minimize inaccuracies introduced.

FIGURE 8-4: ANALOG INPUT MODEL

Note 1: When reading a PORT register, all pins

configu red a s anal og inp uts will read as a

‘0’. Pins configured as digital inputs will

convert as an analog input, according to

the input specification.

2: Analog levels on any pin defined as a

digit al input, may ca use the input buff er to

consume more current than is specified.

Rs < 10K

CPIN

5 pF

VDD

VT ≈ 0.6V

RIC

ILEAKAGE

±500 nA

Vss

AIN

Legend: CPIN = Input Capaci tance

ILEAKAGE = Leakage Current at the pin due to various junctions

RIC = Interconne ct Resista nce

RS= Source I mpedance

VA= Analog Voltage

VT= Threshold Voltage

To ADC Input

PIC16F684

8.2 Comparator Configuration

There are eigh t mod es of operat ion fo r the comp arato r.

The CM<2:0 > bit s of the C MCON0 reg ister are used to

select these modes as shown in Figure 8-5. I/O lines

change as a function of the mode and are designated

as follows:

• Analog function (A): digital input buffer is disabled

• Digital function (D): comparator digital output,

overrides port function

• Normal port function (I/O): independent of

comparator

The port pins denoted as “A” will read as a ‘0’

regardless of the state of the I/O pin or the I/O control

TRIS bit. Pins used as analog inputs should also have

the corresponding TRIS bit set to ‘1’ to disable the

digital output driver. Pins denoted as “D” should have

the corresponding TRIS bit set to ‘0’ to enable the

digital output driver.

FIGURE 8-5: COMPARATOR I/O OPERATING MODES

Note: Compara tor in terr upts sh ould be dis abled

during a Comparator mode change to

preve nt uni nten de d interru pt s .

C1IN- VIN-

VIN+

C1IN+ Off(1)

Comparators Reset (POR Default Value)

CM<2:0> = 000

C2IN- VIN-

VIN+

C2IN+ Off(1)

C1IN- VIN-

VIN+

C1IN+ C1OUT

Two Independent Comparators

CM<2:0> = 100

C2IN- VIN-

VIN+

C2IN+ C2OUT

C1IN- VIN-

VIN+

C1IN+ C1OUT

Two Common Reference Comparators

I/O

CM<2:0> = 011

C2IN- VIN-

VIN+

C2IN+ C2OUT

C1IN- VIN-

VIN+

C1IN+ Off(1)

One Independent Comparator

I/O

CM<2:0> = 101

C2IN- VIN-

VIN+

C2IN+ C2OUT

C1IN- VIN-

VIN+

C1IN+ Off(1)

Comparators Off (Lowest Power)

I/O

CM<2:0> = 111

C2IN- VIN-

VIN+

C2IN+ Off(1)

I/O

C1IN- VIN-

VIN+

C1IN+ C1OUT

Four Inputs Multiplexed to Two Comparators

CM<2:0> = 010

C2IN- VIN-

VIN+

C2IN+ C2OUT

From CVREF Module

CIS = 0

CIS = 1

CIS = 0

CIS = 1

C1IN- VIN-

VIN+

C1OUT(pin)

C1OUT

Two Common Reference Comparators with Outputs

CM<2:0> = 110

C2IN- VIN-

VIN+

C2IN+ C2OUT

C2OUT(pin)

C1IN- VIN-

VIN+

C1IN+ C1OUT

Three Inputs Multiplexed to Two Comparators

CM<2:0> = 001

C2IN- VIN-

VIN+

C2IN+ C2OUT

CIS = 0

CIS = 1

Legend: A = Analog Input, ports always reads ‘0’ CIS = C omparator Input Switch (CMCON0<3>)

I/O = Normal port I/O D = Comparator Digital Output

Note 1: Reads as ‘0’, unless CxINV = 1.

PIC16F684

8.3 Comparator Control

The CMCON0 register (Register 8-1) provides access

to the following comparator features:

• Mode selection

• Output state

• Output pol arit y

• Input switch

8.3.1 COMPARATOR OUTPUT STATE

Each comparator state can always be read internally

via th e a ss oc iat ed CxO UT bit of th e CMCON0 regi ste r.

The comparator outputs are directed to the CxOUT

pins when CM<2:0> = 110. When this mode is

selected, the TRIS bits for the associated CxOUT pins

must be cleared to enable the output drivers.

8.3.2 COMPARATOR OUTPUT POLARITY

Inverting the output of a comparator is functionally

equivalent to swapping the comparator inputs. The

polarity of a comparator output can be inverted by set-

ting the CxINV bits of the CMCON0 register. Clearing

CxINV results in a non-inverted output. A complete

table showing the output state versus input conditions

and the polarity bit is shown in Table 8-1.

TABLE 8-1: OUTPUT STATE VS. INPUT

CONDITIONS

8.3.3 COMPA RATOR INPUT SWITCH

The inve rting input of the comparators may be switched

between two analog pins in the following modes:

• CM<2:0> = 001 (Co mparator C1 only)

• CM<2:0> = 010 (Comparators C1 and C2)

In the above modes, both pins remain in Analog mode

regardless of which pin is selected as the input. Th e CIS

bit of the CMCON0 register controls the comparator

input swi tch.

8.4 Comparator Response Time

The comparator output is indeterminate for a period of

time afte r the change of an i nput source or the selection

of a new refe rence volta ge. This period is refer red to as

the response time. The response time of the

comparator differs from the settling time of the voltage

reference. Therefore, both of these times must be

considered when determining the total response time

to a comparator input change. See Comparator and

Voltage Reference specifications of Section 15.0

“Electrical Specifications” for more details.

8.5 Comparator Interrupt Operation

The comparator interrupt flag is set whenever there is

a change in the output value of the comparator.

Changes are recognized by means of a mismatch

circuit which consists of two latches and an exclusive-

or gate (see Figure 8-2 and Figure 8-3). One latch is

updated with the comparator output level when the

CMCON0 register is read. This latch retains the value

until the next read of the CMCON0 register or the

occurrence of a reset. The other latch of the mismatch

circuit is updated on every Q1 system clock. A

mismatch condition will occur when a comparator

output change is clocked through the second latch on

the Q1 clo ck cycle. The mi smatch cond ition will persis t,

holding the CxIF bit of the PIR1 register true, until either

the CMCON 0 re gist er i s read or the comp ara tor o utp ut

returns to the previous state.

Software will need to maintain information about the

statu s of the comp arator output to dete rmine the actua l

change that has occurred.

The CxIF bit of the PIR1 register is the comparator

interrupt flag. This bit must be reset in software by

clearing it to ‘0’. Since i t is a lso po ssibl e t o writ e a ‘1’ to

this register, a simulated interrupt may be initiated.

The CxIE bi t of the P IE1 register and the PEIE and G IE

bits of the INTCON register must all be set to enable

comparator interrupts. If any of these bits are cleared,

the interru pt is not en abled, alth ough the CxI F bit of the

PIR1 register will still be set if an interrupt condition

occurs.

The use r , in the Interru pt Service Routi ne, can clear th e

interr upt in the foll owin g man ner:

a) Any read or write of CMCON0. This will end the

mismatch condition.

b) Clear the CxIF interrupt flag.

Input Conditions CxINV CxOUT

VIN- > VIN+00

VIN- < VIN+01

VIN- > VIN+11

VIN- < VIN+10

Note: CxOUT refers to both the register bit and

output pin.

Note: A write ope rati on to the CMCON0 reg ister

will also clear the mismatch condition

because all writes include a read

operation at the beginning of the write

cycle.

PIC16F684

A persistent mismatch condition will preclude clearing

the CxIF interrupt flag. Reading CMCON0 will end the

mismatch condition and allow the CxIF bit to be

cleared.

FIGURE 8-6: COMPARATOR

INTERRUPT TIMING W/O

CMCON0 READ

FIGURE 8-7: COMPARATOR

INTERRUPT TIMING WITH

CMCON0 READ

8.6 Operation During Sleep

The comparator, if enabled before entering Sleep m ode,

remains active during Sleep. The additional current

consumed by the comparator is shown separately in

Section 15.0 “Electrical Specifications”. If the

comparator is not used to wake the device, power

consumption can be minimized while in Sleep mode by

turning of f the comparator. The comparator is turned off

by selecting mode CM<2:0> = 000 or CM<2:0> = 111

of the CMCON0 register.

A change to the comparator output can wake-up the

device from Sleep. To enable the comparator to wake

the devic e from Sle ep, the CxIE bi t of the PIE1 reg ister

and the PEIE bit of the INTCON register must be set.

The instruction following the Sleep instruction always

executes following a wake from Sleep. If the GIE bit of

the INTCON register is also set, the device will then

execute the interrupt service routine.

8.7 Effects of a Reset

A device Reset forces the CMCON0 and CMCON1

registers to th eir Res et st ates . This forc es th e Comp ar-

ator module to be in the Comparator Reset mode

(CM<2:0> = 000). Thus, all comparator inputs are

analog inp uts with the comp arator disabled to consume

the smallest current possible.

Note 1: If a change in the CM1CON0 register

(CxOUT) s hould occu r when a read oper-

ation is being executed (start of the Q2

cycle), then the CxIF Interrupt Flag bit of

the PIR1 register may not get set.

2: When either comparator is first enabled,

bias circuitry in the Comparator module

may cause an invalid output from the

comparator until the bias circuitry is stable.

Allow about 1 μs for bias settling then clear

the mismatch condition and interrupt flags

before enabling comparator interrupts.

CxIN+

CxOUT

Set CMIF (level)

CMIF

TRT

reset by software

CxIN+

CxOUT

Set CMIF (level)

CMIF

TRT

reset by software

cleared by CMCON0 read

PIC16F684

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

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

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: Compar ator 2 Output Inversion bit

1 = C2 output inverted

0 = C2 output not inverted

bit 4 C1INV: Compar ator 1 Output Inversion bit

1 = C1 Output inverted

0 = C1 Output not inverted

bit 3 CIS: Comparator Input Switch bit

When CM<2:0> = 010:

1 = C1IN+ connects to C1 VIN-

C2IN+ connects to C2 VIN-

0 = C1IN- connects to C1 VIN-

C2IN- connects to C2 VIN-

When CM<2:0> = 001:

1 = C1IN+ connects to C1 VIN-

0 = C1IN- connects to C1 VIN-

bit 2-0 CM<2:0>: Comparator Mode bits (S ee Figure 8-5)

000 = Comparators off. CxIN pins are configured as analog

001 = Three inputs multiplexed to two c omparators

010 = Four inputs multiplexed to two comparators

011 = Two common reference comparators

100 = Two independent comparators

101 = One independent comparator

110 = Two common reference comparators with outputs

111 = Comparators off. CxIN pins are configured as digital I/O

PIC16F684

8.8 Comparator C2 Gating Timer1

This feat ure can be used to time the d uration or interva l

of analog events. Clearing the T1GSS bit of the

CMCON1 register will enable Timer1 to increment

based on the output of Comparator C2. This requires

that Timer1 is on and gating is enabled. See

Section 6.0 “Timer1 Module with Gate Control” for

details.

It is recommended to synchr onize Comparator C2 with

Timer1 by setting the C2SYNC bit when the comparator

is used as the T imer1 gate source. This ensures Timer1

does not miss a n incr eme nt if the compara tor ch an ges

during an increment.

8.9 Synchronizing Comp arator C2

Output to Timer1

The output of Comparator C2 can be synchronized with

Timer1 by setting the C2SYNC bit of the CMCON1

latched on the falling edge of t he Timer1 clock source.

If a prescaler is used with Timer1, the comparator

output is latched after the prescaling function. To

prevent a race condition, the comparator output is

latched on the falling edge of the Timer1 clock source

and Timer1 increments on the rising edge of its clock

source. Reference the comparator block diagrams

(Figure 8-2 and Figure 8-3) and the Timer1 Block

Diagram (Figure 6-1) for more information.

U-0 U-0 U-0 U-0 U-0 U-0 R/W-1 R/W-0

— — — — — — T1GSS C2SYNC

bit 7 bit 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

bit 7-2 Unimplemented: Read as ‘0’

bit 1 T1GSS: Timer1 Gate Source Select bit(1)

1 = Timer1 gate source is T1G pin (pin should be configured as digital input)

0 = Timer1 gate source is Comparator C2 output

bit 0 C2SYNC: Comparator C2 Output Synchronization bit(2)

1 = Output is synchronized with falling edge of Timer1 clock

0 = Output is asynchronous

Note 1: Refer to Section 6.6 “Timer1 Gate”.

2: Refer to Figure 8-3.

PIC16F684

8.10 Comparator Voltage Reference

The comparator voltage reference module pr ovides an

internally generated voltage reference for the compara-

tors. The following features are available:

• Independent from Comparator operation

• Two 16-level voltage ranges

• Output clamped to VSS

• Ratiometric with VDD

The VRCON register (Register ) controls the voltage

reference module shown in Figure 8-8.

8.10.1 INDEPENDENT OPERATION

The comparator voltage reference is independent of

the comparator configuration. Setting the VREN bit of

the VRCON register will enable the voltage reference.

8.10.2 OUTPUT VOLTAGE SELECTION

The CVREF voltage reference has 2 ranges with 16

voltage levels in each range. Range selection is

controlled by the VRR bit of the VRCON register. The

16 levels are set with the VR<3:0> bits of the VRCON

The CV REF output voltage is determined by the following

equations:

EQUATION 8-1: CVREF OUTPUT VOLTAGE

The full range of VSS to VDD cannot be realized due to

the construction of the module. See Figure 8-8.

8.10.3 OUTPUT CLAMPED TO VSS

The CVREF output voltage can be set to Vss with no

power consumptio n by config uring VRCON as f ollows:

•VREN=0

•VRR=1

•VR<3:0>=0000

This allows the comparator to detect a zero-crossing

while not consuming additional CVREF module curren t.

8.10.4 OUTPUT RATIOMETRIC TO VDD

The comparator voltage reference is VDD derived and

therefore, the CVREF output changes with fluctuations in

VDD. The tested absolute accuracy of the Comparator

Voltage Reference can be found in Section 15.0

“Electrical Specifications”.

VRR 1 (low range):=

VRR 0 (high range):=

CVREF (VDD/4) + =

CVREF (VR<3:0>/24) VDD×=

(VR<3:0> VDD/32)×

VRCON: VOLTAGE REFERENCE CONTROL REGISTER

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

VREN —VRR— VR3 VR2 VR1 VR0

bit 7 bit 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

bit 7 VREN: CVREF Enab le bit

1 = CVREF circuit powered on

0 = CVREF circuit powered down, no IDD drain an d CVREF = VSS.

bit 6 Unimplemented: Read as ‘0’

bit 5 VRR: CVREF Range Selection bit

1 = Low range

0 = High range

bit 4 Unimplemented: Read as ‘0’

bit 3-0 VR<3:0>: CVREF Value Selection bits (0 ≤ VR<3:0> ≤ 15)

When VRR = 1: CVREF = (VR<3 :0>/24) * VDD

When VRR = 0: CVREF = VDD/4 + (VR<3:0>/32) * VDD

PIC16F684

FIGURE 8-8: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM

TABLE 8-2: SUMMARY OF REGISTERS ASSOCIATED WITH THE COMP ARATOR AND V OLT AGE

REFERENCE MODULES

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Val ue on:

POR, BOR

Value on

all othe r

Resets

ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

CMCON1 — — — — — — T1GSS C2SYNC ---- --10 ---- --10

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PORTA — — RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 --uu uu00

PORTC — — RC5 RC4 RC3 RC2 RC1 RC0 --xx 0000 --uu uu00

TRISA — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111

TRISC — — TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111

VRCON VREN —VRR— VR3 VR2 VR1 VR0 0-0- 0000 0-0- 0000

Legend: x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used for comparator.

VRR

VR<3:0>(1)

16-1 Analog

8R R R R R

CVREF to

16 Stages

Comparator

Input

VREN

VDD

MUX

VR<3:0> = 0000

VREN

VRR

Note 1: Care should be taken to ensure VREF remains

within the comparator common mode input range.

See Section 15.0 “Electrical Specifications” for

more detail.

PIC16F684

9.0 ANALOG-TO-DIGITAL

CONVERTER (ADC) MODULE

The Analog-to-Digital Converter (ADC) allows

conversion of an analog input signal to a 10-bit binary

representation of that signal. This device uses analog

inputs, which are multiplexed into a single sample and

hold circuit. The output of the sample and hold is

connected to the input of the converter. The converter

generates a 10-bit binary result via successive

approximation and stores the conversion result into the

ADC result registers (ADRESL and ADRESH).

The ADC voltage reference is software selectable to

either VDD or a v olt age applied to the ex ternal reference

pins.

The ADC can generate an interrupt upon completion of

a conversion. This interrupt ca n be used to wake-up the

device from Sleep.

Figure 9-1 shows the block diagram of the ADC.

FIGURE 9-1: ADC BLOCK DIAGRAM

RA0/AN0

A/D

RA1/AN1/VREF

RA2/AN2

RC0/AN4

VDD

VREF

ADON

GO/DONE

VCFG = 1

VCFG = 0

CHS <3:0>

VSS

RC1/AN5

RC2/AN6

RC3/AN7

RA4/AN3

ADRESH ADRESL

ADFM 0 = Left Justify

1 = Right Justify

PIC16F684

9.1 ADC Configuration

When configuring and using the ADC the following

functio ns must be considere d:

• Port configuration

• Channel selection

• ADC voltage reference selection

• ADC co nversion clock source

• Interrupt control

• Results formatting

9.1.1 PORT CONFIGURATION

The ADC can be used to convert both analog and digital

signals. When converting analog signals, the I/O pin

should be configured for analog by setting the associated

TRIS and ANSEL bits. See the corresponding port

section for more information.

9.1.2 CHANNEL SELECTION

The CHS bi ts of the ADCON0 r egister det ermine whic h

channel is connected to the sample and hold circuit.

When changing channels, a delay is required before

starting the next conversion. Refer to Section 9.2

“ADC Operation” for more information.

9.1.3 ADC VOLTA GE REFERENCE

The VCFG bit of the ADCON0 register provides contro l

of the positive voltage reference. The positive voltage

reference can be either VDD or an external voltage

source. The negative voltage reference is always

connec ted to the ground refe renc e.

9.1.4 CONVERSION CLOCK

The so urce of th e conver sion cloc k is sof tware sele ct-

able via the ADCS bits of the ADCON1 register. There

are seven possible clock options:

•F

OSC/2

•FOSC/4

•FOSC/8

•F

OSC/16

•FOSC/32

•FOSC/64

•F

RC (dedicated internal oscillator)

The time to complete one bit conversion is defined as

TAD. One ful l 1 0-b it c on ve rsi on requires 11 TAD periods

as shown in Figure 9-3.

For correct conversion, the appropriate TAD specificatio n

must be met. See A/D conversion requirements in

Section 15.0 “Electrical Specifications” for more

information. Table 9-1 gives examples of appropriate

ADC clock selections.

TABLE 9-1: ADC CLOCK PERIOD (TAD) VS. DEVICE OPERATING FREQUENCIES (VDD > 3.0V)

Note: Analog voltages on any pin that is defined

as a digital input may cause the input

buffer to conduct excess current.

Note: Unless using the FRC, any changes in the

system clock frequency will change the

ADC clock frequency, which may

adversely affect the ADC result.

ADC Clock Period (TAD) Device Freque ncy (FOSC)

ADC Clock Source ADCS<2:0> 20 MHz 8 MHz 4 MHz 1 MHz

FOSC/2 000 100 ns(2) 250 ns(2) 500 ns(2) 2.0 μs

FOSC/4 100 200 ns(2) 500 ns(2) 1.0 μs(2) 4.0 μs

FOSC/8 001 400 ns(2) 1.0 μs(2) 2.0 μs8.0 μs(3)

FOSC/16 101 800 ns(2) 2.0 μs4.0 μs16.0 μs(3)

FOSC/32 010 1.6 μs4.0 μs8.0 μs(3) 32.0 μs(3)

FOSC/64 110 3.2 μs8.0 μs(3) 16.0 μs(3) 64.0 μs(3)

FRC x11 2-6 μs(1,4) 2-6 μs(1,4) 2-6 μs(1,4) 2-6 μs(1,4)

Legend: Shaded cells are outside of recommended range.

Note 1: The FRC source has a typical TAD time of 4 μs for VDD > 3.0V.

2: These values violate the minimum required TAD time.

3: For faster conversion times, the selection of another clock source is recommended.

4: When the device frequency is greater than 1 MHz, the FRC clock source is only recommended if the

conversion will be perform ed during Sleep.

PIC16F684

FIGURE 9-2: ANALOG-TO-DIGITAL CONVERSION TAD CYCLES

9.1.5 INTERRUPTS

The ADC module allows for the ability to generate an

interrupt upon completion of an analog-to-digital

conversion. The ADC interrupt flag is the ADIF bit in the

PIR1 reg ister. The ADC inte rrupt en able i s the ADIE bit

in the PIE1 register. The ADIF bit must be cleared in

software.

This interrupt can be generated while the device is

operatin g or while in Sle ep. If the device is in Sle ep, the

interrupt will wake-up the device. Upon waking from

Sleep, the next instruction following the SLEEP

instruc tio n is always executed. If the user is attem ptin g

to wake-up from Sleep and resume in-line code

execution, the global interrupt must be disabled. If the

global interrupt is enabled, execution will switch to the

inter rupt se rvi ce rout ine .

Please see Section 9.1.5 “Interrupts” for more

information.

9.1.6 RESULT FORMATTING

The 10- bit A/D conversion resu lt can be suppli ed in two

formats, left justified or right justified. The ADFM bit of

the ADCON0 register controls the output format.

Figure 9-4 shows the two output formats.

FIGURE 9-3: 10-BIT A/D CONVERSION RESULT FORMAT

TAD1TAD2 TAD3TAD4TAD5 TAD6 TAD7 TAD8 TAD9

Set GO/DONE bit

Holding Capacitor is Disconnected from Analog Input (typically 100 ns)

b9 b8 b7 b6 b5 b4 b3 b2

TAD10 TAD11

b1 b0

TCY to TAD

Conversion S tarts

ADRESH and ADRESL registers are loaded,

GO bit is cleared,

ADIF bit is set,

Holding capacitor is connected to analog input

Note: The ADIF bit is set at the completion of

every conversion, regardless of whether

or not the ADC interrupt is enabled.

ADRESH ADRESL

(ADFM = 0)MSB LSB

bit 7 bit 0 bit 7 bit 0

10-bit A/D Result Unimplemented: Read as ‘0’

(ADFM = 1)MSB LSB

bit 7 bit 0 bit 7 bit 0

Unimplemented: Read as ‘0’ 10-bit A/D Result

PIC16F684

9.2 ADC Operation

9.2.1 STARTING A CONVERSION

To enable the ADC module, the ADON bit of the

ADCON0 register must be set to a ‘1’. Setting the

GO/DONE bit of the ADCON0 register to a ‘1’ will st art

the analog-to-digital conversion.

9.2.2 COMPLETION OF A CONVERSION

When the conversion is complete, the ADC module will:

• Clear the GO/DONE bit

• Set the ADIF flag bit

• Update the ADRESH:A DRESL regis ters with new

conversion result

9.2.3 TERMINATING A CONVERSION

If a co nver sion must b e term ina ted be fore comp leti on,

the GO/DONE bit can be cleared in software. The

ADRESH:ADRESL registers will not be updated with

the partially complete analog-to-digital conversion

sample. Instead, the ADRESH:ADRESL register pair

will retain the value of the previous conversion. Addi-

tionall y, a 2 TAD delay is required bef ore another acqu i-

sition can be initiated. Following this delay, an input

acquisition is automatically started on the selected

channel.

9.2.4 ADC OPERATION DURING SLEEP

The ADC module can operate during Sleep. This

requires the ADC clock source to be set to the FRC

option. When the FRC clock source is selected, the

ADC wa its on e additio nal instru ction bef ore sta rting th e

conversion. This allows the SLEEP instruction to be

executed, which can reduce system noise during the

conversion. If the ADC interrupt is enabled, the device

will wake-up from Sleep when the conversion

completes. If the ADC interrupt is disabled, the ADC

module is turned off after the conversion completes,

although the ADON bit remains set.

When the ADC clock source is something other than

FRC, a SLEEP instruction causes the present conver-

sion to be aborted and the ADC module is turned off,

although the ADON bit remains set.

9.2.5 SPECIAL EVENT TRIGGER

The ECCP Special Event Trigger allows periodic ADC

measurements without software intervention. When

this trigger occurs, the GO/DONE bit is set by hardware

and the Timer1 counter resets to zero.

Using the Special Event Trigger does not ensure

proper ADC timing. It is the user’s responsibility to

ensure that the ADC timing requirements are met.

See Section 11.0 “Enhanced Capture/Com-

pare/PWM (With Auto-Shutdown and Dead Band)

Module” for more information.

9.2.6 A/D CONVERSION PROCEDURE

This is an example procedure for using the ADC to

perform an Analog-to-Digita l conve rsion:

1. Configure Port:

• Disable pin output driver (See TRIS register)

• Configure pin as analog

2. Configure the ADC module:

• Select ADC co nversion clock

• Config ure vo lt ag e refere nc e

• Select ADC input channel

• Select result format

• Turn on ADC module

3. Configure ADC interrupt (optional):

• Clear ADC interrupt flag

• Enable ADC interrupt

• Enable peripheral interrupt

• Enable global interrupt(1)

4. Wait the required acquisition time(2).

5. Start conversion by setting the GO/DONE bit.

6. Wait for ADC conversion to complete by one of

the following:

• Polli ng the GO /DO N E bit

• Waiting for the ADC interrupt (interrupts

enabled)

7. Read ADC Result

8. Clear the ADC interrup t flag (requi red if interrupt

is enabled).

Note: The GO/DONE bit shou ld not be set in th e

same instruction that turns on the ADC.

Refer to Section 9.2.6 “A/D Conversion

Procedure”.

Note: A device Reset forces all registers to their

Reset state. Thus, the ADC module is

turned off and any pending conversion is

terminated.

Note 1: The global interrup t can b e dis abled i f the

user is attem pti ng to wak e-up from Sleep

and resume in-line code execution.

2: See Section 9.3 “A/D Acquisition

Requirements”.

PIC16F684

EXAMPLE 9-1: A/D CONVE RSION

;This code block configures the ADC

;for polling, Vdd reference, Frc clock

;and AN0 input.

;

;Conversion start & polling for completion

; are included.

;

BANKSEL ADCON1 ;

MOVLW B’01110000’ ;ADC Frc clock

MOVWF ADCON1 ;

BANKSEL TRISA ;

BSF TRISA,0 ;Set RA0 to input

BANKSEL ANSEL ;

BSF ANSEL,0 ;Set RA0 to analog

BANKSEL ADCON0 ;

MOVLW B’10000001’ ;Right justify,

MOVWF ADCON0 ; Vdd Vref, AN0, On

CALL SampleTime ;Acquisiton delay

BSF ADCON0,GO ;Start conversion

BTFSC ADCON0,GO ;Is conversion done?

GOTO $-1 ;No, test again

BANKSEL ADRESH ;

MOVF ADRESH,W ;Read upper 2 bits

MOVWF RESULTHI ;store in GPR space

BANKSEL ADRESL ;

MOVF ADRESL,W ;Read lower 8 bits

MOVWF RESULTLO ;Store in GPR space

PIC16F684

9.2.7 ADC REGISTER DEFINITIONS

The following registers are used to control the operation of the ADC.

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

ADFM VCFG — CHS2 CHS1 CHS0 GO/DONE ADON

bit 7 bit 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

bit 7 ADFM: A/D Conversion Result Format Select bit

1 = Right justified

0 = Left justified

bit 6 VCFG: V oltage Reference bit

1 = VREF pin

0 = VDD

bit 5 Unimplement ed: Read as ‘0’

bit 4-2 CHS<2:0>: Analog Channel Select bits

000 = AN0

001 = AN1

010 = AN2

011 = AN3

100 = AN4

101 = AN5

110 = AN6

111 = AN7

bit 1 GO/DONE: A/D Conversion Status bit

1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle.

This bit is automatically cleared by hardware when the A/D conversion has completed.

0 = A/D conversion completed/not in progress

bit 0 ADON: ADC Enable bit

1 = ADC is enabled

0 = ADC is disabled and consumes no operating curr ent

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

— ADCS2 ADCS1 ADCS0 — — — —

bit 7 bit 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

bit 7 Unimplement ed: Read as ‘0’

bit 6-4 ADCS<2:0>: A/D Conversion Clock Select bits

000 = FOSC/2

001 = FOSC/8

010 = FOSC/32

x11 = FRC (clock derived from a dedicated internal oscillator = 500 kHz max)

100 = FOSC/4

101 = FOSC/16

110 = FOSC/64

bit 3-0 Unimplemented: Read as ‘0’

PIC16F684

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

ADRES9 ADRES8 ADRES7 ADRES6 ADRES5 ADRES4 ADRES3 ADRES2

bit 7 bit 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

bit 7-0 ADRES<9:2>: ADC Result Register bits

Upper 8 bits of 10-bit conversion result

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

ADRES1 ADRES0 — — — — — —

bit 7 bit 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

bit 7-6 ADRES<1:0>: ADC Result Register bits

Lower 2 bits of 10-bit conversion result

bit 5-0 Reserved: Do not use.

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

— — — — — — ADRES9 ADRES8

bit 7 bit 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

bit 7-2 Reserved: Do not use.

bit 1-0 ADRES<9:8>: ADC Result Register bits

Upper 2 bits of 10-bit conversion result

R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x R/W-x

ADRES7 ADRES6 ADRES5 ADRES4 ADRES3 ADRES2 ADRES1 ADRES0

bit 7 bit 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

bit 7-0 ADRES<7:0>: ADC Result Register bits

Lower 8 bits of 10-bit conversion result

PIC16F684

9.3 A/D Acquisition Requirements

For the A DC t o meet its specif ied 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 9-4. 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), see Figure 9-4.

The maximum recommended impedance for analog

sources is 10 kΩ. As the source impedance is

decreased, the acquisition time may be decreased.

After the analog input channel is selected (or changed),

an A/D acquisition must be done before t he conversion

can be started. To calculate the minimum acquisition

time, Equation 9-1 may be used. This equation

assumes that 1/2 LSb error is used (1024 steps for the

ADC). The 1/2 LSb error is the maximum error allowed

for the ADC to meet its specified resolution.

EQUATION 9-1: ACQUISITION TIME EXAMPLE

TACQ Amplifier Settling Time Hold Capacitor Charging Time Temperature Coefficient++=

TAMP TCTCOFF++=

5µs TCTemperature - 25°C()0.05µs/°C()[]++=

TCCHOLD RIC RSS RS++() ln(1/2047)–=

10pF 1k

10k

++()– ln(0.0004885)=

1.37=µs

TACQ 5µS1.37µS50°C- 25°C()0.05µS/°C()[]++=

7.67µS=

VAPPLIED 1e

Tc–

---------

–

⎝⎠

⎜⎟

⎛⎞

VAPPLIED 11

2047

------------

–

⎝⎠

⎛⎞

VAPPLIED 11

2047

------------

–

⎝⎠

⎛⎞

VCHOLD=

VAPPLIED 1e

TC–

----------

–

⎝⎠

⎜⎟

⎛⎞

VCHOLD=

;[1] V CHOLD charged to within 1/2 lsb

;[2] VCHOLD charge response to VAPPLIED

;combining [1] and [2]

The value for TC can be approximated with th e follow ing eq uations:

Solving for TC:

Therefore:

Temperature 50°C and external impedance of 10k

5.0 V VDD=

Assumptions:

Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out.

2: The charge holding capacitor (CHOLD) is not discharged after each conversion.

3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin

leakage specification.

PIC16F684

FIGURE 9-4: ANALOG INPUT MODEL

FIGURE 9-5: ADC TRANSFER FUNCTION

CPIN

Rs ANx

5 pF

VDD

VT = 0.6V

VT = 0.6V I LEAKAGE

RIC ≤ 1k

Sampling

Switch

SS Rss

CHOLD = 10 pF

VSS/VREF-

Sampling Switch

567891011

(kΩ)

VDD

± 500 nA

Legend: CPIN

I LEAKAGE

RIC

CHOLD

= Input Capacitance

= Threshold Voltage

= Leakage current at the pin due to

= Interconnect Resistance

= Sampling Switch

= Sample/Hold Capacitance

various junctions

RSS

3FFh

3FEh

ADC Output Code

3FDh

3FCh

004h

003h

002h

001h

000h

Full-Scale

3FBh

1 LSB ideal

VSS/VREF-Zero-Scale

Transition VDD/VREF+

Transition

1 LSB ideal

Full-Scale Range

Analog Input Voltage

PIC16F684

TABLE 9-2: SUMMARY OF ASSOCIATED ADC REGISTERS

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

ADCON0 ADFM VCFG — CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000

ADCON1 — ADCS2 ADCS1 ADCS0 — — — — -000 ---- -000 ----

ANSEL ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111

ADRESH A/D Result Register High Byte xxxx xxxx uuuu uuuu

ADRESL A/D Result Register Low Byte xxxx xxxx uuuu uuuu

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIE1 EEIE ADIE CCPIE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCPIF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PORTA — — RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 --uu uuuu

PORTC — — RC5 RC4 RC3 RC2 RC1 RC0 --xx 0000 --uu uuuu

TRISA — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111

TRISC — — TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111

Legend: x = unknown, u = unchanged, — = unimplemented read as ‘0’. Shaded cells are not used for ADC module.

PIC16F684

10.0 DATA EEPROM MEMORY

The EEPROM data memory is readable and writable

during norma l operati on (full VDD range). This memory

is not directly mapped in the register file space.

Instead, it is indirectly addressed through the Special

Function Registers. There are four SFRs used to read

and write this memory:

• EECON1

• EECON2 (not a physically implemented register)

• EEDAT

• EEADR

EEDAT holds the 8-bit da t a fo r read/ write , and EEADR

holds the address of the EEPROM location being

accessed . PIC16F684 has 256 bytes of dat a EEPROM

with an address range from 0h to FFh.

The EEPROM data memory allows byte read and write.

A byte write automatically erases the location and

writes the n ew data (erase be fore write). The EEPROM

data memory is rated for high erase/write cycles. The

write time is controlled by an on-chip timer. The write

time will vary with voltage and temperature as well as

from chip-to-chip. Please refer to AC Specifications in

Section 15.0 “Electrical Specifications” for exact

limits.

When the data memory is code-protected, the CPU

may continue to read and write the data EEPROM

memory. The device programmer ca n no longer access

the data EEPROM data and will read zeroes.

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0

bit 7 bit 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

bit 7-0 EEDATn: Byte Value to Write To or Read From Data EEPROM bits

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0

bit 7 bit 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

bit 7-0 EEADR: Specifies One of 256 Locations for EEPROM Read/Write Operat ion bit s

PIC16F684

10.1 EECON1 and EECON2 Registers

EECON1 is the control register with four low-order bits

physically implemented. The upper four bits are

non-implemented and read as ‘0’s.

Control bits RD and WR initiate read and write,

respectively. These bits cannot be cleared, only set in

software. They are cleared in hardware at completion

of th e r ead or wr i t e ope r a tio n. T he ina bi l it y t o clea r t he

WR bit in software prevents the accidental, premature

termination of a write operation.

The WREN bit, when set, will allow a write operation.

On powe r-up, the WR EN bit is clear. The WRERR bi t is

set when a write operation is interrupted by a MCLR

Reset, or a WDT Time-out Reset during normal

operatio n. In these s ituations , following Reset, the us er

can check the WRERR bit, clear it and rewrite the

location. The data and address will be cleared.

Therefore, the EEDAT and EEADR registers will need

to be re-initialized.

Interrupt fl ag, EEIF bit of the PIR1 reg is ter, is set when

write is complete. This bit must be cleared in software.

EECON2 is not a physical register. Reading EECON2

will read all ‘0’s. The EECON2 register is used

exclusively in the data EEPROM write sequence.

Note: The EECON1, EEDAT and EEADR

registers should not be modified during a

data EEPROM write (WR bit = 1).

U-0 U-0 U-0 U-0 R/W-x R/W-0 R/S-0 R/S-0

— — — — WRERR WREN WR RD

bit 7 bit 0

Legend:

S = Bit can only be set

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

bit 7-4 Unimplemented: Read as ‘0’

bit 3 WRERR: EEPROM Error Flag bit

1 = A write operation is prematurely terminated (any MCLR Reset, any WDT Reset during

normal operation or BOR Reset)

0 = The write operation completed

bit 2 WREN: EEPROM Write Enable bit

1 = Allows write cycles

0 = Inhibits write to the data EEPROM

bit 1 WR: Write Control bit

1 = Initiates a w rite cycl e (The bit is cle ared by hardw are o nce w rite is co mplet e. The WR b it ca n only

be set, not cleared, in software.)

0 = Write cycle to the data EEPROM is complete

bit 0 RD: Read Control bit

1 = Initiates an EEPROM read (Read t akes one cyc le. RD is cleared in hardware . The RD bit can only

be set, not cleared, in software.)

0 = Does not initiate an EEPROM read

PIC16F684

10.2 Reading the EEPROM Data

Memory

To read a data memory location, the user must write the

address to the EEADR register and then set control bit

RD of the EECON1 register , as show n in Example 10-1.

The data is available, at the very next cycle, in the

EEDAT register. Therefore, it can be read in the next

instruction. EEDA T holds thi s value until another read, or

until it is written to by the user (during a wr ite operation).

EXAMPLE 10-1: DATA EEPROM READ

10.3 Writing to the EEPROM Data

Memory

To write an EEPROM data location, the user must first

write the address to the EEADR register and the data

to the EEDAT register. Then the user must follow a

specific sequence to initiate the write for each byte, as

shown in Example 10-2.

EXAMPLE 10-2: DATA EEPROM WRITE

The write will not initiate if the above sequence is not

exactly followed (write 55h to EECON2, write AAh to

EECON2, then set WR bit) for each byte. We strongly

recommend that interrupts be disabled during this

code segment. A cycle count is executed during the

required s equence . Any number th at is not equa l to the

required cycles to execute the required sequence will

prevent the data from being written into the EEPROM.

Additionally, the WREN bit in EECON1 must be set to

enable write. This mechanism prevents accidental

writes to data EEPROM due to errant (unexpected)

code execution (i.e., lost programs). The user should

keep the WREN bit clear at all times, except when

updating EEPROM. The WREN bit is not cleared

by hardware.

After a write sequence has been initiated, clearing the

WREN bit wil l not af fect this writ e cycle. T he WR bit will

be inhibi ted from bei ng s et u nless the WREN b it is se t.

At the completion of the write cycle, the WR bit is

cleared in hardware and the EE Write Complete

Interrupt Flag bit (EEIF) is set. The user can either

enable this interrupt or poll this bit. The EEIF bit of the

PIR1 register must be cleared by software.

10.4 Write Veri fy

Depending on the application, good programming

practice may dictate that the value written to the data

EEPROM should b e verifie d (see Example 10-3) to th e

desired value to be written.

EXAMPL E 10- 3: WRITE VE RIF Y

10.4.1 USING THE DATA EEPROM

The data EEPROM is a high-endurance, byte

addressable array that has been optimized for the

storage of frequently changing information (e.g.,

program variables or other data that are updated often).

When variables in one section change frequently, while

variables in another section do not change, it is possible

to exceed the total number of write cycles to the

EEPROM (specification D124) without exceeding the

total number of write cycles to a single byte

(specifications D120 and D120A). If this is the case,

then a re fr esh of the arra y must be per formed . F or th is

reason, variables that change infrequently (such as

constants, IDs, calibration, etc.) should be stored in

Flash program memory.

BANKSEL EEADR ;

MOVLW CONFIG_ADDR ;

MOVWF EEADR ;Address to read

BSF EECON1,RD ;EE Read

MOVF EEDAT,W ;Move data to W

BANKSEL EECON1 ;

BSF EECON1,WREN ;Enable write

BCF INTCON,GIE ;Disable INTs

BTFSC INTCON,GIE ;See AN576

GOTO $-2 ;

MOVLW 55h ;Unlock write

MOVWF EECON2 ;

MOVLW AAh ;

MOVWF EECON2 ;

BSF EECON1,WR ;Start the write

BSF INTCON,GIE ;Enable INTS

Required

Sequence

BANKSELEEDAT ;

MOVF EEDAT,W ;EEDAT not changed

;from previous write

BSF EECON1,RD ;YES, Read the

;value written

XORWF EEDAT,W

BTFSS STATUS,Z ;Is data the same

GOTO WRITE_ERR ;No, handle error

: ;Yes, continue

PIC16F684

10.5 Protection Against Spurious Write

There are conditions when the user may not want to

write to the data EEPROM memory. To protect against

spurious EEPROM writes, various mechanisms have

been buil t in. On power-up, WR EN is cleare d. Also, the

Power-up Timer (64 ms duration) prevents

EEPROM write.

The wri te in iti ate sequence an d the WREN bi t tog eth er

help prevent an accidental write during:

• Brown-out

•Power Glitch

• Software Malfunction

10.6 Data EEPROM Operation During

Code-Protect

Data memo ry can be code-pro tected b y program ming

the CPD bit in the Configuration Word register

(Register 12-1) to ‘0’.

When the data memory is code-protected, the CPU is

able to read and write data to the data EEPROM. It is

recommended to code-protect the program memory

when code-protecting data memory. This prevents

anyone from programming zeroes over the existing

code (which will execute as NOPs) to reach an added

routine, programmed in unused program memory,

which outputs the contents of data memory.

Programming unused locations in program memory to

‘0’ will also help prevent data memory code protection

from becom ing breac hed .

TABLE 10-1: SUMMARY OF ASSOCIATED DAT A EEPROM REGISTERS

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Valu e on:

POR, BOR

Value on

all othe r

Resets

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

EEDAT EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0 0000 0000 0000 0000

EEADR EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0 0000 0000 0000 0000

EECON1 — — — — WRERR WREN WR RD ---- x000 ---- q000

EECON2(1) EEPROM Control Register 2 ---- ---- ---- ----

Legend: x = unkn own , u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition. Shaded cells are not used by the Data

EEPROM module.

Note 1: EECON2 is not a physical register.

PIC16F684

11.0 ENHANCED

CAPTURE/COMPARE/PWM

(WITH AUTO-SHUTDOWN AND

DEAD BAND) MODULE

The Enhanced Capture/Compare/PWM module is a

peripheral which allows the user to time and control

different events. In Capture mode, the peripheral

allows the timing of the duration of an event. The

Compare mode allows the user to trigger an external

event when a predetermined amount of time has

expired. The PWM mode can generate a Pulse-Width

Modulated signal of varying frequency and duty cycle.

Table 11-1 shows the timer resources required by the

ECCP module.

TABLE 11-1: ECCP MODE – TIMER

RESOURCES REQUIRED

ECCP Mode Timer Resource

Capture Timer1

Compare Timer1

PWM Timer2

R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0

P1M1 P1M0 DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0

bit 7 bit 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

bit 7-6 P1M<1:0>: P W M Ou tp ut Co nf igu rat ion bits

If CCP 1M<3:2> = 00, 01, 10:

xx = P1A assigned as Capture/Compare input; P1B, P1C, P1D assigned as port pins

If CCP1M<3:2> = 11:

00 = Singl e outpu t; P1A modu la ted ; P1 B, P1 C, P1D assig ne d as port pin s

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 DC1B<1:0>: PWM Duty Cycle Least Significant bits

Capture mode:

Unused.

Compare mode:

Unused.

PWM mode:

These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L.

bit 3-0 CCP1M<3:0>: ECCP Mod e Se lec t bits

0000 = Capture/Compare/PWM off (resets ECCP module)

0001 = Unused (rese rv ed )

0010 = Compare mode, toggle output on match (CCP1IF bit is set)

0011 = Unused (rese rv ed )

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, set output on match (CCP1IF bit is set)

1001 = Compare mode, clear output on match (CCP1IF bit is set)

1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set, CCP1 pin is

unaffected)

1011 = Compare mode, trigger spe cial event (CCP1IF bit is set; CCP1 resets TMR1 or TMR2, and st arts

an A/D conversion, if the ADC module is enabled)

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

PIC16F684

11.1 Capture Mode

In Capture mode, CCPR1H:CCPR1L captures the

16-bit val ue of the TMR1 register when an event occurs

on pin CCP1. An event is defined as one of the

following and is configured by the CCP1M<3:0> bits of

the CCP1CON register:

• Every falling edge

• Every rising edge

• Every 4th rising edge

• Every 16th rising edge

When a cap ture i s m ade, the I nterrupt Re quest Flag bit

CCP1IF of the PIR1 register is set. The interrupt flag

must be cleared in software. If another capture occurs

before the value in the CCPR1H, CCPR1L register pair

is read, the old captured value is overwritten by the new

captured value (see Figure 11-1).

11.1.1 CCP1 PIN CONFIGURATION

In Capture mode, the CCP1 pin should be configured

as an input by setting the associated TRIS control bit.

FIGURE 11-1: CAP TURE MODE

OPERATION BLOCK

DIAGRAM

11.1.2 TIMER1 MODE SELECTION

T imer1 must be running in T imer mode or Synchroni zed

Counter mode for the CCP module to use the capture

feature. In Asynchronous Counter mode, the capture

operation may not work.

11.1.3 SOFTWARE INTERRUPT

When the Capture mode is changed, a false capture

interrupt may be generated. The user should keep the

CCP1IE i nterrupt en able bit of the PIE1 regis ter clear to

avoid false interrupts. Additionally, the user should

clear the CCP1IF interrupt flag bit of the PIR1 register

following any change in operating mode.

11.1.4 CCP PRESCALER

There are four prescaler settings specified by the

CCP1M<3:0> bits of the CCP1CON register.

Whenever the CCP module is turned off, or the CCP

module is not in Capture mode, the prescaler counter

is cleared. Any Reset will clear the prescal er counter.

Switching from one capture prescaler to another does not

clear the prescaler and may generate a false interrupt. To

avoid this unexpected operation, turn the module off by

clearing the CCP1CON register before changing the

prescaler (see Example 11-1).

EXAMPLE 11 -1: CHANGING BETWEE N

CAPTURE PRESCALERS

Note: If the C CP1 pin is c onfigured as an outpu t,

a write to the port can cause a capture

condition.

CCPR1H CCPR1L

TMR1H TMR1L

Set Flag bit CCP1IF

(PIR1 register )

Capture

Enable

CCP1CON<3:0>

Prescaler

÷ 1, 4, 16

and

Edge Detect

CCP1

System Clock (FOSC)

BANKSEL CCP1CON ;Set Bank bits to point

;to CCP1CON

CLRF CCP1CON ;Turn CCP module off

MOVLW NEW_CAPT_PS ;Load the W reg with

; the new prescaler

; move value and CCP ON

MOVWF CCP1CON ;Load CCP1CON with this

; value

PIC16F684

11.2 Compare Mode

In C ompare mo de, t he 16- bit CC PR1 re gist er va lue is

constantly compared against the TMR1 register pair

value. When a match occurs, the CCP module may:

• Toggle th e CCP1 out put

• Set the CCP1 output

• Clear the CCP1 output

• Generate a Special Event Trigger

• Generate a Software Interrupt

The action on the pin is based on the value of the

CCP1M<3:0> control bits of the CCP1CON register.

All Compare modes can generate an interrupt.

FIGURE 11-2: COMPARE MODE

OPERATION BLOCK

DIAGRAM

11.2.1 CCP1 PIN CONFIGURATION

The user m us t co nfi gure the C CP 1 pin a s an out put b y

clearing the associated TRIS bit.

11.2.2 TIMER1 MODE SELECTION

In Compare mode, Timer1 must be running in either

Timer mode or Synchronized Counter mode. The

compare operation may not work in Asynchronous

Counter mode.

11.2.3 SOFTWARE INTERRUPT MODE

When Generate Software Interrupt mode is chosen

(CCP1M<3:0> = 1010), the CCP module does not

assert control of the CCP1 pin (see the CCP1CON

11.2.4 SPECIAL EVENT TRIGGER

When Special Event Trigger mode is chosen

(CCP1M<3:0> = 1011), the CCP module does the

following:

• Resets Timer1

• Starts an ADC conversion if ADC is enabled

The CCP module does not assert control of the CCP1

pin in this mode (see the CCP1CON register).

The Special Event Trigger output of the CCP occurs

immediately upon a match between the TMR1H,

TMR1L register pair and the CCPR1H, CCPR1L

reset until th e next r ising ed ge of the T imer1 clock. This

allows the CCPR1H, CCPR1L register pair to

effectively provide a 16-bit programmable period

Note: Clearing the CCP1CON register will force

the CCP1 compare output latch to the

default low level. This is not the port I/O

data l atc h.

CCPR1H CCPR1L

TMR1H TMR1L

Comparator

ROutput

Logic

Specia l Event Trigge r

Set CCP1IF Interrupt Flag

(PIR1)

Match

TRIS

CCP1CON<3:0>

Mode Select

Output Enable

Special Event Trigger will:

• Clear TMR1H and TMR1L registers.

• NOT set interrupt flag bit TMR1IF of the PIR1 register.

• Set the GO/DONE bit to start the ADC conversion.

CCP1 4

Note 1: The Special Event Trigger from the CCP

module does not set interrupt flag bit

TMR1IF of the PIR1 registe r.

2: Removing the match condition by

changing the contents of the CCPR1H

and CCPR1L register pair, between the

clock edge that generates the Special

Event Trigger and the clock edge that

generates the T imer1 Reset, will p reclude

the Reset from occurring.

PIC16F684

11.3 PWM Mode

The PWM mode generates a Pulse-Width Modulated

signal on the CCP1 pin. The duty cycle, period and

resolution are determined by the following registers:

•PR2

•T2CON

• CCPR1L

• CCP1CON

In Pulse-Width Modulation (PWM) mode, the CCP

module produce s up to a 10 -bit resoluti on PWM outp ut

on the CCP1 pin. Since the CCP1 pin is multiplexed

with the POR T dat a latch, the TRIS for that pi n must be

cleared to enable the CCP1 pin output driver.

Figure 11-3 shows a simplified block diagram of PWM

operation.

Figure 11-4 shows a typical waveform of the PWM

signal.

For a st ep by step pr ocedure on h ow to set up the CCP

module for PWM operation, see Section 11.3.7

“Setup for PWM Operation”.

FIGURE 11-3: SIMPLIFIED PWM BLOCK

DIAGRAM

The PWM output (Figure 11-4) has a time base

(period) and a time that the output stays high (duty

cycle).

FIGURE 11-4: CCP PWM OUTPUT

Note: Clearing the CCP1CON register will

relinquish CCP1 control of the CCP1 pin.

CCPR1L

CCPR1H(2) (Slave)

Comparator

TMR2

PR2

(1)

Duty Cycle Registers CCP1CON<5:4>

Clear Timer2 ,

toggle CCP1 pin and

latch duty cycle

Note 1: The 8-bit timer TMR2 register is concatenated

with the 2-bit internal system cloc k (FOSC), or

2 bits of the prescaler , to create the 10-bit time

base.

2: In PWM mode, CCPR1H is a read-only register

TRIS

CCP1

Comparator

Period

Pulse Width

TMR2 = 0

TMR2 = CCPR1L:CCP1CON<5:4>

TMR2 = PR2

PIC16F684

11.3.1 PWM PERIO D

The PWM period is specified by the PR2 register of

Timer2. The PWM period can be calculated using the

formula of Equation 11-1.

EQUATION 11-1: PWM PERIOD

When TM R2 is equa l to PR2, t he followi ng three ev ents

occur on t he next inc rement cy cle:

• TMR2 is cl eare d

• The CCP1 pi n is se t. (Ex cep tio n: If the PWM duty

cycle = 0%, the pin will not be set.)

• The PWM dut y cycl e is latched from CCPR1L i nto

CCPR1H.

11.3.2 PWM DUTY CYCLE

The PWM duty cycle is specified by writing a 10-bit

value to multiple registers: CCPR1L register and

CCP1<1:0> bits of the CCP1CON register. The

CCPR1L contains the eight MSbs and the CCP1<1:0>

bits of the CCP1CON register contain the two LSbs.

CCPR1L and CCP1<1:0> bits of the CCP1CON

value is not latched into CCPR1H until after the period

completes (i.e., a match between PR2 and TMR2

registers occurs). While using the PWM, the CCPR1H

Equation 11-2 is used to calculate the PWM pulse

width.

Equat ion 11-3 is used to calcula te the PWM duty cy cl e

ratio.

EQUATION 11-2: PULSE WIDTH

EQUATION 11-3: DUTY CYCLE RATIO

The CCPR1H register and a 2-bit internal latch are

used to dou ble buf fer th e PWM duty cycle. Thi s doubl e

buffering is es sential for glitchless PWM operation.

The 8-bit timer TMR2 register is concatenated with

either the 2-bit internal system clock (FOSC), or 2 bits of

the prescaler , to create the 10-bit time ba se. The system

clock is used if the Timer2 prescaler is set to 1:1.

When the 10-bit time base matches the CCPR1H and

2-bit latch, then the CCP1 pin is cleared (see

Figure 11-3).

11.3.3 PWM RESOLUTIO N

The res olution de termines the number of avai lable dut y

cycles for a given period. For example, a 10-bit resolution

will result in 1024 discrete duty cycles, whereas an 8-bit

resolu ti on will re su lt in 2 56 discrete du ty c ycl es .

The maximum PWM resolution is 10 bits when PR2 is

255. The resolution is a function of the PR2 register

value as shown by Equation 11-4.

EQUATION 11-4: PWM RESOLUTION

TABLE 11-2: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)

TABLE 11-3: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 8 MHz)

Note: The Timer2 postscaler (see Section 7.1

“Timer2 Operation”) is not used in the

determination of the PWM frequency.

PWM Period PR2()1+[]4TOSC •••=

(TM R2 Presc ale Value)

Note: If the pulse width value is greater than the

period the assigned PWM pin(s) will

remain unchanged.

Pulse Width CCPR1L:CCP1CON<5:4>()

•

TOSC

•

(TMR2 Prescale Value)

Duty Cycle Ratio CCPR1L:CCP1CON<5:4>()

4PR2 1+()

-----------------------------------------------------------------------=

Resolution 4PR2 1+()[]log 2()log

------------------------------------------ bits=

PWM Frequency 1.22 kHz 4.88 kHz 19.53 kHz 78.12 kHz 156.3 kHz 208.3 kHz

Timer Prescale (1, 4, 16) 16 4 1 1 1 1

PR2 Value 0xFF 0xFF 0xFF 0x3F 0x1F 0x17

Maximum Resolution (bits) 10 10 10 8 7 6.6

PWM Frequency 1.22 kHz 4.90 kHz 19.61 kHz 76.92 kHz 153.85 kHz 200.0 kHz

Timer Prescale (1, 4, 16) 16 4 1 1 1 1

PR2 Value 0x65 0x65 0x65 0x19 0x0C 0x09

Maximum Resolution (bits) 8 8 8 6 5 5

PIC16F684

11.3.4 OPERATION IN SLEEP MODE

In Sleep mode, the TMR2 register will not increment

and the st ate of the module will not change. If the CCP1

pin is dri ving a value , it wi ll cont inue to d rive th at valu e.

When the device wakes up, TMR2 wil l continue from it s

previous state.

11.3.5 CHANGES IN SYSTEM CLOCK

FREQUENCY

The PWM frequency is derived from the system clock

frequency. Any changes in the system clock frequency

will result in changes to the PWM frequency. See

Section 3.0 “Oscillator Module (With Fail-Safe

Clock Monitor)” for additional deta ils.

11.3.6 EFFECTS OF RESET

Any Reset will force all ports to Input mode and the

CCP registers to their Reset states.

11.3.7 SETUP FOR PWM OPERATION

The following steps should be taken when configuring

the CCP module for PWM operation:

1. Disable the PWM pin (CCP1) output driver by

setting the associated TRIS bit.

2. Set the PWM period by loading the PR2 register .

3. Configure the CCP module for the PWM mode

by loading the CCP1CON register with the

appropriate values.

4. Set the PWM duty cycle by loading the CCPR1L

5. Configure and start Timer2:

• Clear the TMR2IF interrupt flag bit of the

PIR1 register.

• Set the Timer2 prescale value by lo ading the

T2CKPS bits of the T2CON register.

• Enable Timer2 by setting the TMR2ON bit of

the T2CON register.

6. Enable PWM outpu t afte r a ne w PW M cy cle has

started:

• Wait until Timer2 overflows (TMR2IF bit of

the PIR1 register is set).

• Enabl e the CCP1 pin outp ut driver by clearing

the associated TRIS bit.

PIC16F684

11.4 PWM (Enhanced Mode)

The Enhanced PWM Mode can generate a PWM signal

on up to four different output pins with up to 10-bits of

resolution. It can do this through four different PWM

output modes:

• Single PWM

• Half-Bridge PWM

• Full-Bridge PWM, Forward mode

• Full-Bridge PWM, Reverse mode

To select an Enhanced PWM mode, the P1M bits of the

CCP1CON register must be se t appropriately.

The PWM outputs are multiplexed with I/O pins and are

designated P1A, P1B, P1C and P1D. The polarity of the

PWM pins is configurable and is selected by setting the

CCP1M bits in the CC P1CON register appropriately.

Table 11-4 shows the pin assignments for each

Enhanced PWM mode.

Figure 11-5 shows an example of a simplified block

diagram of the Enhanced PWM module.

FIGURE 11-5: EXAMPLE SIMPLIFI ED B LOCK DIA GRAM O F THE E NH ANCED PWM MO DE

TABLE 11-4: EXAMPLE PIN ASSIGNMENTS FOR VARIOUS PWM ENHANCED MODES

Note: To prevent the generation of an

incomplete waveform when the PWM is

first enabl ed, the ECCP module w aits unti l

the start of a new PWM period before

generating a PWM signal.

CCPR1L

CCPR1H (Slave)

Comparator

TMR2

Comparator

PR2

(1)

Duty Cycle Registers CCP1<1:0>

Clear Timer2,

toggle PWM pin and

latch duty cycle

Note 1: The 8-b i t tim er T MR2 re gi ste r is con c ate na ted wi th the 2- bit i nte rna l Q cl ock, or 2 bits of the p res cal er to cr eat e t he 10- bi t

time base.

TRIS

CCP1/P1A

TRIS

P1B

TRIS

P1C

TRIS

P1D

Output

Controller

P1M<1:0> 2CCP1M<3:0>

PWM1CON

CCP1/P1A

P1B

P1C

P1D

Note 1: The TRIS register value for each PWM output must be configured appropriately.

2: Clearing the CCP1CON register will relinquish ECCP control of all PWM output pins.

3: Any pin not used by an Enhanced PWM mode is available for alternate pin functions

ECCP Mode P1M CCP1/P1A P1B P1C P1D

Single 00 Yes No No No

Half-Bridge 10 Yes Yes No No

Full-Bridg e, Forwar d 01 Yes Yes Yes Yes

Full-Bridg e, Reve rse 11 Yes Yes Yes Yes

PIC16F684

FIGURE 11-6: EXAMPLE PWM (ENHANCED MODE) OUTPUT RELATIONSHIPS (ACTIVE-HIGH

STATE)

Period

Signal PR2+1

P1M<1:0>

P1A Modulated

P1B Modulated

P1A Active

P1B Inactive

P1C Inactive

P1D Modulated

P1A Inactive

P1B Modulated

P1C Active

P1D Inactive

Pulse

Width

(Single Output)

(Half-Bridge)

(Full-Bridge,

Forward)

(Full-Bridge,

Reverse)

Delay(1) Delay(1)

Relationships:

• Perio d = 4 * TOSC * (PR2 + 1) * (TMR2 Prescal e Value)

• Pulse Width = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale V alue)

• Delay = 4 * TOSC * (PWM1CON<6:0>)

Note 1: Dead-band delay is programmed using the PWM1CON register (Section 11.4.6 “Programmable Dead-Band Delay

mode”).

PIC16F684

FIGURE 11-7: EXAMPLE ENHANCED PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE)

Period

Signal PR2+1

P1M<1:0>

P1A Modulated

P1B Modulated

P1A Active

P1B Inactive

P1C Inact ive

P1D Modulated

P1A Inactive

P1B Modulated

P1C Active

P1D Inact ive

Pulse

Width

(Single Output)

(Half-Bridge)

(Full-Bridge,

Forward)

(Full-Bridge,

Reverse)

Delay(1) Delay(1)

Relationships:

• Perio d = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value)

• Pulse Width = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale V alue)

• Delay = 4 * TOSC * (PWM1CON<6:0>)

Note 1: Dead-band delay is programmed using the PWM1CON register (Section 11.4.6 “Programmable Dead-Band Delay

mode”).

PIC16F684

11.4.1 HALF-BRIDGE MODE

In Half-Bridge mode, two pins are used as outputs to

drive push-pull lo ad s. The PWM output sign al is output

on the C CP1/P1 A pin, whi le the co mpleme ntary PWM

output signal is output on the P1B pin (see

Figure 11-16). This mode can be used for half-bridge

applications, as shown in Figure 11-17, or for

full-brid ge ap pli ca tio ns , wh ere fou r power s wi tc hes ar e

being modulated with two PWM signals.

In Half-Bridge mode, the programmable dead-band delay

can be used to prevent shoot-through current in

half-bridge power devices. The value of the PDC<6:0>

bits of the PWM1CON register 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 11.4.6 “Programmable Dead-Band Delay

mode” for more details of the dead-band delay

operations.

Since the P1A and P1B outputs are multiplexed with

the PORT data latches, the associated TRIS bits must

be cleared to configure P1A and P1B as outputs.

FIGURE 11-8: EXAMPLE OF

HALF-BRIDGE PWM

OUTPUT

FIGURE 11-9: EXAMP LE OF HALF-BRIDGE APPLICATIONS

Period

Pulse Width

(1)

P1A(2)

P1B(2)

td = Dead-B and Delay

Period

(1) (1)

Note 1: At this t ime, the T MR2 reg ister is equal to the

PR2 register.

2: Output signals are shown as active-high.

P1A

P1B

FET

Driver

FET

Driver

Load

FET

Driver

FET

Driver

V+

Load

FET

Driver

FET

Driver

P1A

P1B

Standard Half-Bridge Circuit (“Push-Pull”)

Half-Bridge Output Driving a Full-Bridge Circuit

PIC16F684

11.4.2 FULL-BRIDGE MODE

In Full-Bridge mode, all four pins are used as outputs.

An example of full-bridge application is shown in

Figure 11-10.

In the Forward mode, pin CCP1/P1A is driven to its active

state, p in P1 D is m odul ated, whil e P1B and P1C will be

driven to their inactive state as shown in Figure 11-11.

In the Reverse mode, P1C is driven to its active state,

pin P1B is modulated, while P1A and P1D wi l l be driv en

to their i n ac t iv e s tate a s s h ow n Figure 11-11.

P1A, P1B, P1C and P1D outputs are multiplexed with

the POR T dat a latc hes. The a ssoc iated T RIS bit s mus t

be cleared to configure the P1A, P1B, P1C and P1D

pins as outputs.

FIGURE 11-10: EXAMPLE OF FULL-BRIDGE APPLICATION

P1A

P1C

FET

Driver

FET

Driver

V+

V-

Load

FET

Driver

FET

Driver

P1B

P1D

QB QD

PIC16F684

FIGURE 11-11: EXAMPLE OF FULL-BRIDGE PWM OUTPUT

Period

Pulse Width

P1A(2)

P1B(2)

P1C(2)

P1D(2)

Forw a r d M o de

(1)

Period

Pulse Width

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.

2: Output signal is shown as active-high.

PIC16F684

11.4.2.1 Direction Change in Full-Bridge

Mode

In the Full-Bri dge mode, the P1M1 bit in the CCP1CON

direction. When the application firmware changes this

direction control bit, the module will change to the new

direction on the next PWM cycle.

A direction change is initiated in software by changing

the P1M1 bit of the CCP1CON register. The following

sequen ce oc c urs fo ur Timer2 cyc les prio r t o the en d of

the current PWM period:

• The modu lated output s (P1B and P1D) are placed

in their inactive state.

• The associated unmodulated outputs (P1A and

P1C) are switched to drive in the opposite

direction.

• PWM mo dulati on resumes at the be ginnin g of the

next period.

See Figure 11-12 for an illustration of this sequence.

The Full-Bridge mode does not provide dead-band

delay. As one outpu t is modulated at a tim e, dead-band

delay is generally not required. There is a situation

where dead-band delay is 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 11-13 shows an example of the PWM direction

chan gi ng from for w ar d to rev ers e , at a ne ar 100 % du ty

cycle. In this example, at time t1, the output P1A and

P1D become inactive, while output P1C becomes

active. Since the turn off time of the power devices is

longer than the turn on time, a shoot-through current

will flow through power devices QC and QD (see

Figure 11-10) for the duration of ‘t’. The same

phenomenon will occur to power devices QA and QB

for PWM di rec t io n ch an ge fr o m reve rs e to forw a rd.

If changing PWM direction at high duty cycle is required

for an app lication, two possible solutions f or eliminatin g

the shoot-through current are:

1. Reduce PWM duty cycle for one 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.

FIGURE 11-12: EXAMPLE OF PWM DIRECTION CHANGE

Pulse Width

Period(1)

Signal

Note 1: The direction bit P1M1 of the CCP1CON register 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 c ycle. The

modulated P1B and P1D signals are inactive at this time. The len gth of this time is four Timer2 counts.

Period

(2)

P1A (Active-High)

P1B (Active-High)

P1C (Active-High)

P1D (Active-High)

Pulse Width

PIC16F684

FIGURE 11-13: EXAMPLE OF PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE

11.4.3 START-UP CONSIDERATIONS

When any PWM mode is used, the application

hardware must use the proper external pull-up and/or

pull-down resistors on the PWM output pins.

The CCP1M<1:0> bits of the CCP1CON register allow

the us er t o ch oose whe the r the P WM out put si gna ls are

active-high or active-low for each pair of PWM output pins

(P1A/P1C and P1B/P1D). The PWM output polarities

must be selecte d bef ore the PWM pi n output dri vers ar e

enabled. Changing the polarity configuration while the

PWM pin output drivers are enabled is not recommended

since it may result in damage to the application circuits.

The P1A, P1B, P1C and P 1D output latches may not be

in the proper states when the PWM module is

initialized. Enabling the PWM pin output drivers at the

same time as the Enhanced PWM modes may cause

damage to t he applicati on circuit. The En han ce d PWM

modes must be enabled in the proper Output mode and

complete a full PWM cycle before enabling the PWM

pin output drivers. The completion of a full PWM cycle

is indicated by the TMR2IF bit of the PIR1 register

being set as the second PWM period begins.

Forward Period Reverse Period

P1A

TON

TOFF

T = TOFF – TON

P1B

P1C

P1D

External Switch D

Potential

Shoot-Through Current

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

Note: When the microcontroller is released from

Reset, all of the I/O pins are in the

high-impedance state. The external cir-

cuits must keep t he powe r switch devic es

in the OFF state until the microcontroller

drives the I/O pins with the proper signal

levels or activates the PWM output(s).

PIC16F684

11.4.4 ENHANCED PWM

AUTO-SHUTDOWN MODE

The PWM mod e supp orts an Auto-Shut dow n m ode that

will disable the PWM outputs when an external

shutdown event occurs. Auto-Shutdown mode places

the PWM output pins into a predetermined state. This

mode is used to help prevent the PWM from damaging

the application.

The auto-shutdown sources are selected using the

ECCPASx bits of the ECCPAS register. A shutdown

event may be generated by:

•A logic ‘0’ on the INT pin

• Comparator 1

• Comparator 2

• Setting the ECCPASE bit in firmware

A shutdown condition is indicated by the ECCPASE

(Auto-Shutdown Event Status) bit of the ECCPAS

normally. If the bit is a ‘1’, the PWM outputs are in the

shutdown state.

When a shutdow n event oc curs, two things ha ppen:

The ECCPASE bit is set to ‘1’. The ECCPASE will

remain set until cleared in firmware or an auto-restart

occurs (see Section 11.4.5 “Auto-Restart Mode ” ).

The enabled PWM pins are asynchronously placed in

their shutdown states. The PWM output pins are

grouped into pairs [P1A/P1C] and [P1B/P1D]. The state

of each pin pair is determined by the PSSAC and

PSSBD bits of the ECCPAS register. Each pin pair may

be placed into one of three states:

• Drive logic ‘1’

• Drive logic ‘0’

• Tri-state (high-impedance)

CONTROL REGISTER

U-0 U-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 PSSBD0

bit 7 bit 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

bit 7 ECCPASE: ECCP Auto-Shutdown Event Status bit

1 = A shutdown event has occurred; ECCP outputs are in shutdown state

0 = ECCP outputs are operating

bit 6-4 ECCPAS<2:0>: ECCP Auto-shutdown Source Select bits

000 = Auto-Shutdown is disabled

001 = Comparator 1 output change

010 = Comparator 2 output change

011 = Either Comparator 1 or 2 change

100 =V

IL on INT pin

101 =V

IL on INT pin or Comparator 1 change

110 =V

IL on INT pin or Comparator 2 change

111 =V

IL on INT pin or Comparator 1 or 2 change

bit 3-2 PSSACn: Pins P1A and P1C Shutdown State Control bits

00 = Drive pins P1A and P1C to ‘0’

01 = Drive pins P1A and P1C to ‘1’

1x = Pins P1A and P1C tri-state

bit 1-0 PSSBDn: Pins P1B and P1D Shutdown State Control bits

00 = Drive pins P1B and P1D to ‘0’

01 = Drive pins P1B and P1D to ‘1’

1x = Pins P1B and P1D tri-state

PIC16F684

FIGURE 11-14: PWM AUTO-SHUTDOWN WITH FIRMWARE RESTART (PRSEN = 0)

11.4.5 AUTO-RESTART MODE

The Enhanced PWM can be configured to automati-

cally restart the PWM signal once the auto-shutdown

condition has been removed. Auto-restart is enabled by

setting the PRSEN bit in the PWM1CON register.

If auto-restart is enabled, the ECCPASE bit will remain

set as long as the auto-shutdown condition is active.

When the auto-shutdown condition is removed, the

ECCPASE bit will be cleared via hardware and normal

operation will resume.

FIGURE 11-15: PWM AUTO-SHUTDOWN W ITH AUTO-RESTART ENABLED (PRSEN = 1)

Note 1: The auto-shutdown condition is a

level-based signal, not an edge-based

signal . As l ong as the level is pr esent , the

auto-shutdown wi ll persist.

2: Writing to the ECCPASE bit is disabled

while an auto-shutdown condition

persists.

3: Once the auto-shutdown condition has

been removed and the PWM restarted

(either through firmware or auto-restart)

the PWM signal will always restart at the

beginning of the next 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

Shutdown

PWM

ECCPASE bit

Activity

Event

Shutdown

Event Occurs Shutdown

Event Cle ars PWM

Resumes

Normal PWM

Start of

PWM Period

PIC16F684

11.4.6 PROGRAMMABLE DEAD-BAND

DELAY MODE

In half-b ridge applications where all power switches are

modul ate d at t he P WM fr equ ency, th e pow er sw it ches

normall y 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

of f), both s witc hes ma y be on for a sh ort period of time

until one switch completely turns off. During this brief

interval , a ve ry hig h curre nt (sh oot- through curren t) will

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

delaye d to al low the o ther swi tch to compl etely turn of f.

In Half-Bridge mode, a digitally programmable

dead-band delay is available to avoid shoot-through

current fro m destroying the bri dge power switches . The

delay occurs at the signal transition from the non-active

state to the active state. See Section FIGURE 11-17:

“Example of Half-Bridge Applications” for

illustration. The lower seven bits of the associated

PWM1CON register (Register 11-3) sets the delay

period in terms of microcontroller instruction cycles

(TCY or 4 TOSC).

FIGURE 11-16: EXAMPLE OF

HALF-BRIDGE PWM

OUTPUT

FIGURE 11-17: EXAMPLE OF HALF-BRIDGE APPLICATIONS

Period

Pulse Width

(1)

P1A(2)

P1B(2)

td = Dead-B and 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.

P1A

P1B

FET

Driver

FET

Driver

V+

V-

Load

Standard Half-Bridge Circuit (“Push-Pull”)

PIC16F684

TABLE 11-5: SUMMARY OF REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND PWM

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 PDC5 PDC4 PDC3 PDC2 PDC1 PDC0

bit 7 bit 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

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 PDC<6:0>: PWM Delay Count bits

PDCn = Number of FOSC/4 (4 * TOSC) cycles between the scheduled time when a PWM signal

should transition active and the actual time it transitions active

Note 1: Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe

mode is enable d.

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all othe r

Resets

CCPR1L Capture/Compare/PWM Register 1 Low Byte xxxx xxxx uuuu uuuu

CCPR1H Capture/Compare/PWM Register 1 High Byte xxxx xxxx uuuu uuuu

CCP1CON P1M1 P1M0 DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 0000 0000 0000 0000

CMCON0 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0000 0000 0000

CMCON1 — — — — — — T1GSS C2SYNC ---- --10 ---- --10

ECCPAS ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1 PSSBD0 0000 0000 0000 0000

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PR2 Timer2 Module Period Register 1111 1111 1111 1111

PWM1CON PRSEN PDC6 PDC5 PDC4 PDC3 PDC2 PDC1 PDC0 0000 0000 0000 0000

T1CON T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu

T2CON — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000

TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

TMR2 T imer2 Module Register 0000 0000 0000 0000

TRISA —— TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111

TRISC —— TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111

Legend: - = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Capture,

Compare and PWM.

PIC16F684

12.0 SPECIAL FEATURES OF THE

CPU

The PIC16F684 has a host of features intended to

maximize system reliability, minimize cost through

elimination of external components, provide power

saving features and offer code protection.

These features are:

• Reset

- Power-on Reset (P OR)

- Power-up Timer (PWRT)

- Oscillator Start-up Timer (OST)

- Brown-out Reset (BOR)

• Interrupts

• Watchdog Timer (WDT)

• Oscillator selection

• Sleep

• Code protection

• ID Locations

• In-Circuit Serial Programming

The PIC16F684 has two timers that offer necessary

delays on power-up. One is the Oscillator Start-up

Timer (OST), intended to keep the chip in Reset until

the crystal oscillator is stable. The other is the

Powe r-up Timer (PWRT), which prov ides a fixed del ay

of 64 ms (nomin al) on power-u p only, designe d to kee p

the part in Reset while the power supply stabilizes.

There is al so circ uitry to res et the dev ice if a b rown-out

occurs, which can use the Power-up Timer to provide

at least a 64 ms Reset. With these three

functions-on-chip, most applications need no external

Reset circuitry.

The Sleep mode is de signe d to of fer a very low-c urrent

Power-Down mode. The user ca n wake -up fro m Slee p

through:

• External Reset

• Watchdog Timer Wake-up

• An interrupt

Several oscillator options are also made available to

allow the part to fit the application. The INTOSC option

saves system cost while the LP crystal option saves

power. A set of configuration bits are used to select

various options (see Register 12-1).

12.1 Configuration Bits

The Configuration bits can be programmed (read as

‘0’), or left unprogrammed (read as ‘1’) to select various

device configurations as shown in Register 12-1.

These bits are mapped in program memory location

2007h.

Note: Address 2007h is beyond the user program

memory space. It belongs to the special

configuration memory space

(2000h-3FFFh), which can be accessed

only during programming. See

“PIC12F6XX/16F6XX Memory Program-

ming Specification” (DS41204) for more

information.

PIC16F684

— — —— FCMEN IESO BOREN1 BOREN0

bit 15 bit 8

CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0

bit 7 bit 0

Legend:

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

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

bit 15-12 Unimplemented: Read as ‘1’

bit 11 FCMEN: Fail-Safe Clock Monitor Enabled bit

1 = Fail-Safe Clock Monitor is enabled

0 = Fail-Safe Clock Monitor is disabled

bit 10 IESO: Internal External Switchover bit

1 = Internal External Switchover mode is enabled

0 = Internal External Switchover mode is disabled

bit 9-8 BOREN<1:0>: Brown-out Reset Selection bits(1)

11 = BOR enabled

10 = BOR enabled during operation and disabled in Sleep

01 = BOR controlled by SBOREN bit of the PCON register

00 = BOR disabled

bit 7 CPD: Data Code Protection bit(2)

1 = Data memory code protection is disabled

0 = Data memory code protect ion is enabled

bit 6 CP: Code Protection bit(3)

1 = Program memory code protection is disabled

0 = Program memory code protection is enabled

bit 5 MCLRE: RA3/MCLR pin function select bit(4)

1 = RA3/MCLR pin function is MCLR

0 = RA3/MCLR pin function is digital input, MCLR internally tie d to VDD

bit 4 PWRTE: Power-up Timer Enable bit

1 = PWRT disabled

0 = PWRT enabled

bit 3 WDTE: Watchdog Ti mer Enable bit

1 = WDT enabled

0 = WDT disabled and can be enabled by SWDTEN bit of the WDTCON register

bit 2-0 FOSC<2:0>: Oscillator Selection bits

111 = RC oscillator: CLKOUT function on RA4/OSC2/CLKOUT pin, RC on RA5/OSC1/CLKIN

110 = RCIO oscillator: I/O function on RA4/OSC2/CLKOUT pin, RC on RA5/OSC1/CLKIN

101 = INT OSC os ci ll at or : CL KOUT fu nct io n on RA4/OSC2/CLKOUT pin, I/O f un cti on on RA5/OSC1/CLKIN

100 = INTOSCIO oscillator: I/O function on RA4/OSC2/CLKOUT pin, I/O function on RA5/OSC1/CLKIN

011 = EC: I/O function on RA4/OSC2/CLKOUT pin, CLKIN on RA5/OSC1/CLKIN

010 = HS oscillator: High-speed crystal/resonator on RA4/OSC2/CLKOUT and RA5/OSC1/CLKIN

001 = XT oscillator: Crystal/resonator on RA4/OSC2/CLKOUT and RA5/OSC1/CLK IN

000 = LP oscillator: Low-power crystal on RA4/OSC2/CLKOUT and RA5/OSC1/CLKIN

Note 1: Enabling Brown-out Reset does not automatically enable Power-up Timer.

2: The entire data EEPROM will be erased when the code protection is turned off.

3: The entire program memory will be erased when the code protection is turned off.

4: When MCLR is asserted in INTOSC or RC mode, the internal clock oscillator is disabled.

PIC16F684

12.2 Calibration Bits

Brown-out Reset (BOR), Power-on Reset (POR) and

8 MHz internal oscillator (HFINTOSC) are factory cali-

brated. These calibration values are stored in fuses

located in the Calibration Word (2009h). The Calibra-

tion Word is not erased when using the specified bulk

erase sequence in the “PIC12F6XX/16F6XX Memory

Programm ing Specific ation” (DS412 44) and thus, does

not require reprogramming.

12.3 Reset

The PIC1 6F684 diffe rentiates betw een various ki nds of

Reset:

a) Power-on Reset (POR)

b) WDT Reset during normal operation

c) WDT Reset during Sleep

d) MCLR Reset during normal operation

e) MCLR Reset during Sleep

f) Brown-out Reset (BOR)

Some regi sters a re not af fected in a ny Rese t conditio n;

their status is un kn ow n on POR a nd un ch ang ed i n any

other Reset. Most other registers are reset to a “Reset

state” on:

• Power- on Reset

•MCLR

Reset

•MCLR

Reset during Sleep

• WDT Reset

• Brown-out Reset (BOR)

WDT wake-up does not cause register resets in the

same manner as a WDT Reset since wake-up is

viewed as the resumptio n of no rm al op era t ion . T O an d

PD bits are set or cleared differently in different Reset

situati ons, as indicat ed in Table 12-2. Software c an use

these bits to determine the nature of the Reset. See

Table 12-4 for a full description of Reset states of all

registers.

A simplif ied block diagra m of the On-Chip Rese t Circu it

is sh own i n Figure 12-1.

The MCLR Reset path has a noise filter to detect and

ignore small pulses. See Section 15.0 “Electrical

Specifications” for pulse-width specifications.

FIGURE 12-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT

External

Reset

MCLR/VPP pin

VDD

OSC1/

WDT

Module

VDD Rise

Detect

OST/PWRT

LFINTOSC

WDT

Time-out

Power-on Reset

OST

10-bit Ripple Counter

PWRT

Chip_Reset

11-bit Ripple Counter

Reset

Enable OST

Enable PWRT

SLEEP

Brown-out(1)

Reset SBOREN

BOREN

CLKI pin

Note 1: Refer to the Configuration Word register (Register 12-1).

PIC16F684

12.3.1 POWER-ON RESET (POR)

The on-chip POR circuit holds the chip in Reset until

VDD has reached a high enough level for proper

operation. To take advantage of the POR, simply

connect the MCLR pin through a resistor to VDD. This

will eliminate external RC components usually needed

to create Power-on Reset. A maximum rise time for

VDD is required. See Section 15.0 “Electrical

Specifications” for details. If the BOR is enabled, the

maximum rise time specification does not apply. The

BOR circuitry will keep the device in Reset until VDD

reaches VBOR (see Section 12.3.4 “Brown-Out Reset

(BOR)”).

When the device starts normal operation (exits the

Reset condition), device operating parameters (i.e.,

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

ensure proper operation. If these conditions are not

met, the device must be held in Reset until the

operating conditions are met.

For additional information, refer to Application Note

AN607, “Power-up Trouble Shooting” (DS00607).

12.3.2 MCLR

PIC16F684 has a noise filter in the MCLR Reset path.

The filter will detect and ignore small pul ses.

It should be noted that a WDT Reset does not drive

MCLR pin low.

Voltages applied to the MCLR pin that exceed its

specification can result in both MCLR Resets and

excessive current beyond the device specification

during the ESD event. For this reason, Microchip

recommends that the MCLR pin no longer be tied

directly to VDD. The use of an RC network , as shown in

Figure 12-2, is suggeste d.

An internal MCLR option is enabled by clearing the

MCLRE bit in the Configuration Word register. When

MCLRE = 0, the Reset signal to the chip is generated

internally. When the MCLRE = 1, the RA3/MCLR pin

becomes an external Reset input. In this mode, the

RA3/MCLR pin has a we ak pull-up to VDD.

FIGURE 12-2: RECOMMENDED MCLR

CIRCUIT

12.3.3 POWER-UP TIMER (PWRT)

The Power-up Timer provides a fixed 64 ms (nominal)

time-out on power-up only, from POR or Brown-out

Reset. The Power-up Timer operates from the 31 kHz

LFINTOSC oscillator. For more information, see

Section 3.5 “Internal Clock Mo des”. Th e ch ip is ke pt

in Reset as long as PWRT is active. The PWRT delay

allows the VDD to rise to an acceptable level. A

Configuration bit, PWRTE, can disable (if set) or enable

(if cleared or programmed) the Power-up Timer. The

Power-up Timer should be enabled when Brown-out

Reset is enabled, although it is not required.

The Power- up Timer de lay w ill varies from c hip -to-c hi p

due to:

•V

DD variation

• Temperature variation

• Process variation

See DC parameters for details (Section 15.0

“Electrical Specifications”).

Note: The POR circuit does not produce an

internal Reset when VDD declines. To

re-enable the POR, VDD must reach Vss

for a minimum of 100 μs.

Note: Voltage spikes below VSS at the MCLR

pin, induc ing cu rrent s gre ater than 80 mA,

may ca use la tch-up . Thus , a ser ies res is-

tor of 50-100 Ω should be used when

applying a “low” level to the MCLR pin,

rather than pulling this pin directly to VSS.

VDD

PIC®

MCLR

1kΩ (or greater)

0.1 μF

(optional, not critical)

100 Ω

(needed with capacitor)

SW1

(optional)

MCU

PIC16F684

12.3.4 BROWN-OUT RESET (BOR)

The BOREN0 and BOREN1 bits in the Configuration

Word register select one of four BOR modes. Two

modes have been added to a llow softw are or hardwa re

control of the BOR enable. When BOREN<1:0> = 01,

the SBOREN bit of the PCON register enables/disables

the BOR, allowing it to be controlled in software. By

selecting BOREN<1:0> = 10, the BOR is automatically

disabled in Sleep to conserve power and enabled on

wake-up. In this mode, the SBOREN bit is disabled.

See Register 12-1 for the Configuration Word

definition.

A brown-out occurs when VDD falls below VBOR for

greater than parameter TBOR (see Section 15.0

“Electrical Specifications”). The brown-out condition

will reset the device. This will occur regardless of VDD

slew rate. A Brown-out Reset may not occur if VDD falls

below VBOR for less than parameter TBOR.

On any Reset (Power-on, Brown-out Reset, Watchdog

T imer , et c.), the ch ip will remai n in Reset until VDD rises

above VBOR (see Figure 12-3). If enabled, the

Power-up Timer w i ll b e in vo ke d by th e R es et a nd k ee p

the chip in Reset an additional 64 ms.

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-u p Timer will be re-initialized. Onc e VDD

rises above VBOR, the Power-up Timer will execute a

64 ms Reset.

12.3.5 BO R CAL IBRA TIO N

The PIC16F684 stores the BOR calibration values in

fuses located in the Calibration Word register (2008h).

The Cali bration Word reg ister is not erased when using

the specified bulk erase sequence in the

“PIC12F6XX/16F6XX Memory Programming Specifi-

cation” (DS41204) and thus, does not require

reprogramming.

FIGURE 12-3: BROWN-OUT SITUATIONS

Note: The Power-up Timer is enabled by the

PWRTE bit in the Configuration Word

Note: Address 2008h is beyond the user pro-

gram memory space. It belongs to the

special configuration memory space

(2000h-3FFFh), which can be accessed

only during programming. See

“PIC12F6XX/16F6XX Memory Program-

ming Specification” (DS41204) for more

information.

64 ms(1)

VBOR

VDD

Internal

Reset

VBOR

VDD

Internal

Reset 64 ms(1)

< 64 ms

64 ms(1)

VBOR

VDD

Internal

Reset

Note 1: 64 ms delay only if PWRTE bit is programmed to ‘0’.

PIC16F684
DS41202F-page 102 © 2007 Microchip Technology Inc.
12.3.6 TIME-OUT SEQUENCE
On power-up, the time-out seque nce is a s follows: 
• PWRT time-out is invoked after POR has expired.
• OST is activated after the PWRT time-out has 
expired.
The total time-out will vary based on oscillator
configuration and PWR TE bit status. For example, in  EC
mode with PWRTE bit erased (PWRT disabled), there
will be no time-out at all. Figure 12-4, Figure 12-5 and
Figure 12-6 depict time-out sequences. The device can
execute code from the INTOSC while OST is active by
enabling Two-Speed Start-up or Fail-Safe Monitor (see
Section 3.7.2 “Two-speed Start-up Sequence” and
Section 3.8 “Fail-Safe Clock Monitor”).
Since the  time-outs oc cur from the POR  pulse, if MCLR
is kept low lon g enough, the time-out s will expire. Then,
bringing MCLR high will begin execution immediately
(see Figure 12-5). This is useful for testing purposes or
to synchronize more than one PIC16F684 device
operating in parallel.
Table 12-5 shows the Reset conditions for some
special registers, while Table 12-4 shows the Reset
conditions for all the registers. 
12.3.7 POWER CONTROL (PCON) 
REGISTER 
The Power Control register PCON (address 8Eh) has
two Status bits to indicate what type of Reset occurred
last.
Bit 0 is BOR (Brown-out). BOR is unknown on
Power-on Reset. It must then be set by the user and
checked on subsequent Resets to see if BOR = 0,
indicating that a Brown-out has occurred. The BOR
Status bit is a “don’t care” and is not necessarily
predictable if the brown-out circuit is disabled
(BOREN<1:0>  = 00 in the Configuration Word
register).
Bit 1 is  POR (Power-on Reset). It is a ‘0’ on Power-on
Reset  and unaf fec ted oth erwise. T he user m ust write  a
‘1’ to this bit following a Power-on Reset. On a subse-
quent Reset, if POR is ‘0’, it will indicate that a
Power-on Reset has occurred (i.e., VDD may have
gone too low).
For more information, see Section 4.2.4 “Ultra
Low-Power Wake-up” and Section 12.3.4
“Brown-Out Reset (BOR)”.
TABLE 12-1: TIME-OUT IN VARIOUS SITUATIONS
TABLE 12-2: STATUS/PCON BITS AND THEIR SIGNIFICANCE
TABLE 12-3: SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT RESET   
Oscillator Configuration Power-up Brown-out Reset Wake-u p from 
Sleep
PWRTE = 0PWRTE = 1PWRTE = 0PWRTE = 1
XT, HS, LP TPWRT + 1024 • 
TOSC 1024 • TOSC TPWRT + 1024 • 
TOSC 1024 • TOSC 1024 • TOSC
RC, EC, INTOSC TPWRT —TPWRT ——
POR BOR TO PD Condition
0x11Power-on Reset
u011Brown-out Reset
uu0uWDT Reset
uu00WDT Wake-up
uuuuMCLR Reset during normal operation
uu10MCLR Reset during Sleep
Legend: u = unchanged, x = unknown
Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: 
POR, BOR
Value on 
all other 
Resets(1)
PCON — — ULPWUE SBOREN ——PORBOR --01 --qq --0u --uu
STATUS IRP RP1 RP0 TO PD ZDC C0001 1xxx 000q quuu
Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition. 
Shaded cell s are not us ed by BOR.
Note 1: Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation.

PIC16F684

FIGURE 12-4: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 1

FIGURE 12-5: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 2

FIGURE 12-6: TIME-OUT SEQUENCE ON POWER-UP (MCLR WITH VDD)

TPWRT

TOST

VDD

MCLR

Internal POR

PWRT T ime-out

OST Time-out

Internal Reset

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

TPWRT

PIC16F684

TABLE 12-4: INITIALIZATION CONDITION FOR REGISTERS

Reset

MCLR Reset

WDT Reset

Brown-out Reset(1)

Wake-up from Sleep through

Interrupt

Wake-up from Sleep through

WDT Time-out

W—xxxx xxxx uuuu uuuu uuuu uuuu

INDF 00h/80h xxxx xxxx xxxx xxxx uuuu uuuu

TMR0 01h xxxx xxxx uuuu uuuu uuuu uuuu

PCL 02h/82h 0000 0000 0000 0000 PC + 1(3)

STATUS 03h/83h 0001 1xxx 000q quuu(4) uuuq quuu(4)

FSR 04h/84h xxxx xxxx uuuu uuuu uuuu uuuu

PORTA(6) 05h --x0 x000 --u0 u000 --uu uuuu

PORTC(6) 07h --xx 0000 --uu 0000 --uu uuuu

PCLATH 0Ah/8Ah ---0 0000 ---0 0000 ---u uuuu

INTCON 0Bh/8Bh 0000 0000 0000 0000 uuuu uuuu(2)

PIR1 0Ch 0000 0000 0000 0000 uuuu uuuu(2)

TMR1L 0Eh xxxx xxxx uuuu uuuu uuuu uuuu

TMR1H 0Fh xxxx xxxx uuuu uuuu uuuu uuuu

T1CON 10h 0000 0000 uuuu uuuu -uuu uuuu

TMR2 11h 0000 0000 0000 0000 uuuu uuuu

T2CON 12h -000 0000 -000 0000 -uuu uuuu

CCPR1L 13h xxxx xxxx uuuu uuuu uuuu uuuu

CCPR1H 14h xxxx xxxx uuuu uuuu uuuu uuuu

CCP1CON 15h 0000 0000 0000 0000 uuuu uuuu

PWM1CON 16h 0000 0000 0000 0000 uuuu uuuu

ECCPAS 17h 0000 0000 0000 0000 uuuu uuuu

WDTCON 18h ---0 1000 ---0 1000 ---u uuuu

CMCON0 19h 0000 0000 0000 0000 uuuu uuuu

CMCON1 1Ah ---- --10 ---- --10 ---- --uu

ADRESH 1Eh xxxx xxxx uuuu uuuu uuuu uuuu

ADCON0 1Fh 00-0 0000 00-0 0000 uu-u uuuu

OPTION_REG 81h 1111 1111 1111 1111 uuuu uuuu

TRISA 85h --11 1111 --11 1111 --uu uuuu

TRISC 87h --11 1111 --11 1111 --uu uuuu

PIE1 8Ch 0000 0000 0000 0000 uuuu uuuu

PCON 8Eh --01 --0x --0u --uq(1, 5) --uu --uu

OSCCON 8Fh -110 x000 -110 q000 -uuu uuuu

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

Note 1: If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.

2: One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).

3: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt

vector (0004h).

4: See Table 12-5 for Reset value for specific condition.

5: If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bi t 0 = u.

6: Port pins with analog functions controlled by the ANSEL register will read ‘0’ immediately after a Reset

even though the data latches are either undefined (POR) or unchanged (other Resets).

PIC16F684

TABLE 12-5: INITIALIZATION CONDITION FOR SPECIAL REGISTERS

OSCTUNE 90h ---0 0000 ---u uuuu ---u uuuu

ANSEL 91h 1111 1111 1111 1111 uuuu uuuu

PR2 92h 1111 1111 1111 1111 1111 1111

WPUA 95h --11 -111 --11 -111 uuuu uuuu

IOCA 96h --00 0000 --00 0000 --uu uuuu

VRCON 99h 0-0- 0000 0-0- 0000 u-u- uuuu

EEDAT 9Ah 0000 0000 0000 0000 uuuu uuuu

EEADR 9Bh 0000 0000 0000 0000 uuuu uuuu

EECON1 9Ch ---- x000 ---- q000 ---- uuuu

EECON2 9Dh ---- ---- ---- ---- ---- ----

ADRESL 9Eh xxxx xxxx uuuu uuuu uuuu uuuu

ADCON1 9Fh -000 ---- -000 ---- -uuu ----

Condition Program

Counter Status

Power-on Reset 000h 0001 1xxx --01 --0x

MCLR Reset during normal operation 000h 000u uuuu --0u --uu

MCLR Reset during Sleep 000h 0001 0uuu --0u --uu

WDT R eset 000h 0000 uuuu --0u --uu

WDT Wake-up PC + 1 uuu0 0uuu --uu --uu

Brown-out Reset 000h 0001 1uuu --01 --u0

Interrupt Wake-up from Sleep PC + 1(1) uuu1 0uuu --uu --uu

Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’.

Note 1: When the w ake-up is due to an interrupt and Gl obal Interrup t Enable bit, G IE, is set, the PC is loade d with

the inter rupt vector (0004h) afte r execution of PC + 1.

TABLE 12-4: INITIALIZATION CONDITION FOR REGISTERS (CONTINUED)

Reset

MCLR Reset

WDT Reset (Continued)

Brown-out Reset(1)

Wake-up from Sleep through

Interrupt

Wake-up from Sleep through

WDT Time-ou t (Continued )

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

Note 1: If VDD goes too low, Power-on Reset will be activated and registers will be affected differently.

2: One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up).

3: When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt

vector (0004h).

4: See Table 12-5 for Reset value for specific condition.

5: If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bi t 0 = u.

6: Port pins with analog functions controlled by the ANSEL register will read ‘0’ immediately after a Reset

even though the data latches are either undefined (POR) or unchanged (other Resets).

PIC16F684

12.4 Interrupts

The PIC16F684 has 11 sources of interrupt:

• External Inte rrup t RA2/INT

• Timer0 Overflow Interrupt

• PORTA Change Interrupts

• 2 Comparator Interrupts

• A/D Interrupt

• Timer1 Overflow Interrupt

• Timer2 Match Interrupt

• EEPROM Data Write Interrupt

• Fail-Safe Clock Monitor Interrupt

• Enhanced CCP Interrupt

The Interrup t Control register (INTCON) and Peripheral

Interrupt Request Register 1 (PIR1) record individual

interrupt requests in flag bits. The INTCON register

also has individual and global interrupt enable bits.

The Global Interrupt Enable bit, GIE of the INTCON

disables (if cleared) all interrupts. Individual interrupts

can be disabled through their corresponding enable

bits in the INTCON register and PIE1 register. GIE is

cleared on Reset.

When an interrupt is serviced, the following actions

occu r aut omatically:

• The GIE i s clea red to disable an y fu rthe r interrupt.

• The return address is pushed onto the stack.

• The PC is loaded with 0004h.

The Return from Interrupt instruction, RETFIE, exits

the interrupt routine, as well as sets the GIE bit, which

re-enabl es unm as ke d inte rrupts.

The following interrupt flags are contained in the

INTCON register:

• INT Pin Interrupt

• PORTA Change Interrupt

• Timer0 Overflow Interrupt

The perip heral interru pt flags ar e cont ained in the PIR1

contained in the PIE1 register.

The following interrupt flags are contained in the PIR1

• EEPROM Data Write Interrupt

• A/D Interrupt

• 2 Comparator Interrupts

• Timer1 Overflow Interrupt

• Timer2 Match Interrupt

• Fail-Safe Clock Monitor Interrupt

• Enhanced CCP Interrupt

For external interrupt events, such as the INT pin or

PORTA change interrupt, the interrupt latency will be

three or four instruction cycles. The exact latency

depends upon when the interrupt event occurs (see

Figure 12-8). The latency is the same for one or

two-cycle instructions. Once in the Interrupt Service

Routine, the source(s) of the interrupt can be

determined by polling the interrupt flag bits. The

interrupt flag bit(s) must be cleared in software before

re-enabling interrupts to avoid multiple interrupt

requests.

For additional information on Timer1, Timer2,

comparators, ADC, data EEPROM or Enhanced CCP

modules, refer to the respective peripheral section.

12.4.1 RA2/INT INTERRUPT

The external interrupt on the RA2/INT pin is

edge-trig gered; either on t he rising e dge i f the INTEDG

bit of the OPTION register is set, or the falling edge, if

the INTE DG bit i s clear. When a v alid e dge ap pears o n

the RA2/I NT pin, the IN TF bit of the INTC ON register i s

set. This interrupt can be di sabled by clearing the IN TE

control bit of the INTCON register. The INTF bit must

be cleared by softwa re i n the Interrupt Serv ic e Routine

before r e-enabl ing t his interrup t. The RA2/INT interru pt

can wake-up the processor from Sleep, if the INTE bit

was set prior to going into Sleep. See Section 12.7

“Power-Down M ode (Sleep)” f or deta ils on Sleep and

Figure 12-10 for timing of wake-up from Sleep through

RA2/INT interrupt.

Note 1: Individual interrupt flag bits are set,

regardless of the status of their

corresponding mask bit or the GIE bit.

2: When an instruction that clears the GIE

bit is executed, any interrupts that were

pending for execution in the next cycle

are ignored. The interrupts, which were

ignored, are still pending to be serviced

when the GIE bit is set again.

Note: The ANSEL and CMCON0 registers must

be initialized to configure an analog

channel as a digital input. Pins configured

as analog inputs will read ‘0’ and cannot

generate an interrupt.

PIC16F684

12.4.2 TIMER0 INTERRUPT

An overflow (FFh → 00h) in the TMR0 register will set

the T0IF bit of the INTCON register. The interrupt can

be enabled/disabled by setting/clearing T0IE bit of the

INTCON register. See Section 5.0 “Timer0 Module”

for operation of the Timer0 module.

12.4.3 PORTA INTERRUPT-ON-CHANGE

An input change on PORTA sets the RAIF bit of the

INTCON register. The interrupt can be

enabled /disable d by settin g/clearin g the RAIE bi t of the

INTCON register. Plus, individual pins can be

configured through the IOCA register.

FIGURE 12-7: INTE RRUPT LOGIC

Note: If a change on the I/O pin should occur

when any PORTA operation is being

execute d, then the RAIF inte rrupt flag may

not get set.

TMR1IF

TMR1IE

C1IF

C1IE

T0IF

T0IE

INTF

INTE

RAIF

RAIE

GIE

PEIE

Wake-up (If in Sleep mode)(1)

Inte rrup t to C PU

EEIE

EEIF

ADIF

ADIE

IOC-RA0

IOCA0

IOC-RA1

IOCA1

IOC-RA2

IOCA2

IOC-RA3

IOCA3

IOC-RA4

IOCA4

IOC-RA5

IOCA5

TMR2IF

TMR2IE

CCP1IF

CCP1IE

OSFIF

OSFIE

C2IF

C2IE

Note 1: Some peripherals depend upon the system clock for

operation. Since the system clock is suspended during Sleep, only

those peripherals which do not depend upon the system clock will wake

the part from Sleep. See Section 12.7.1 “Wake-up from Sleep”.

PIC16F684

FIGURE 12-8: INT PIN INTERRUPT TIMING

TABLE 12-6: SUMMARY OF REGISTERS ASSOCIATED WITH INTERRUPTS

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000

IOCA — — IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0 --00 0000 --00 0000

PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000

PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000

Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition.

Shaded cells are not used by the interrupt module.

Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4 Q2Q1 Q3 Q4

OSC1

CLKOUT

INT p i n

INTF flag

(INTCON reg.)

GIE bit

(INTCON reg.)

INSTRUCTION FLOW

Instruction

Fetched

Instruction

Executed

Interrupt Latency

PC PC + 1 PC + 1 0004h 0005h

Inst (0004h) Inst (0005h)

Dummy Cycle

Inst (PC) Inst (PC + 1)

Inst (PC – 1) Inst (0004h)

Dummy Cycle

Inst (PC)

—

Note 1: INTF flag is sampled here (every Q1).

2: Asynchronous interrupt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time. Latency

is the same whether Inst (PC) is a single cycle or a 2-cycle instruction.

3: CLKOUT is available only in INTOSC and RC Oscillator modes.

4: For minimum width of INT pulse, refer to AC specifications in Section 15.0 “Electrical Specifications”.

5: INTF is enabled to be set any time during the Q4-Q1 cycles.

(1) (2)

(3) (4)

(5)

(1)

PIC16F684

12.5 Context Saving During Interrupts

During an interrupt, only the return PC value is saved

on the stack. Typically, users may wish to save key

registers during an interrupt (e.g., W and STATUS

registers). This must be implemented in software.

Temporary holding registers W_TEMP and

STATUS_TEMP should be placed in the last 16 bytes

of GPR (see Figure 2-2). These 16 locations are

common to all banks and do not require banking. This

makes context save and restore operations simpler.

The code shown in Ex ample 12-1 can be used to:

• Store the W register

• Store the STATUS register

• Execute the ISR code

• Restore the Status (and Bank Select Bit register)

• Restore the W register

EXAMPLE 12-1: SAVING ST ATUS AND W REGISTERS IN RAM

Note: The PIC16F684 does not require saving

the PCLATH. However, if computed

GOTOs are used in both the ISR and the

main code, the PCLATH must be saved

and restored in the ISR.

MOVWF W_TEMP ;Copy W to TEMP register

SWAPF STATUS,W ;Swap status to be saved into W

;Swaps are used because they do not affect the status bits

MOVWF STATUS_TEMP ;Save status to bank zero STATUS_TEMP register

:(ISR) ;Insert user code here

SWAPF STATUS_TEMP,W ;Swap STATUS_TEMP register into W

;(sets bank to original state)

MOVWF STATUS ;Move W into STATUS register

SWAPF W_TEMP,F ;Swap W_TEMP

SWAPF W_TEMP,W ;Swap W_TEMP into W

PIC16F684

12.6 Wat chdog Timer (WDT)

The WDT has the following features:

• Operates from the LFINTOSC (31 kHz)

• Contain s a 16-bit prescaler

• Shares an 8-bit prescaler with Timer0

• Time-out period is from 1 ms to 268 seconds

• Configuration bit and software controlled

WDT is cleared under certain conditions described in

Table 12-7.

12.6.1 WDT OSCILLATO R

The WDT derives its time base from the 31 kHz

LFINTOSC. The LTS bit of the OSCCON regi ste r does

not reflect that the LFINTOSC is enabled.

The value of WDTCON is ‘---0 1000’ on all R ese ts.

This gives a nominal time base of 17 ms.

12.6.2 WDT CONTROL

The WDTE bit is located in the Configuration Word

When the WDTE bit i n the Configurati on Word register

is set, the SWDTEN bit of the WDTCON register has no

effect. If WDTE is clear, then the SWDTEN bit can be

used to e nable and d isable the WDT. Setting the b it will

enable it and clearing the bit will disable it.

The PSA and PS<2:0> bits of the OPTION register

have the same function as in previous versions of the

PIC16F684 Family of microcontrollers. See

Section 5.0 “Timer0 Module” for more information.

FIGURE 12-9: WATCHDOG TIMER BLOCK DIAGRAM

Note: When the Oscillator Start-up Timer (OST)

is invoked, the WDT is held in Reset,

bec ause the WD T Ri pple C ounte r i s us ed

by the OST to perform the oscillator delay

count. When the OST count has expired,

the WDT will begin counting (if enabled).

TABLE 12-7: WDT STATUS

Conditions WDT

WDTE = 0

Cleared

CLRWDT Command

Oscillator Fail Detected

Exit Sleep + System Clock = T1OSC, EXTRC, INTRC, EXTCLK

Exit Sleep + System Clock = XT, HS, LP Cleared until the end of OST

31 kHz

PSA

16-bit WDT Prescaler

From Timer0 Clock Source

Prescaler(1)

PS<2:0>

PSA

WDT Time -out

To Timer0

WDTPS<3:0>

WDTE from the Configuration Word Register

SWDTEN from WDTCON

LFINTOSC Clock

Note 1: This is the shared Timer0/WDT prescaler . See Section 5.0 “Timer0 Module” for more information.

PIC16F684

TABLE 12-8: SUMMARY OF REGISTERS ASSOCIATED WITH WATCHDOG TIMER

U-0 U-0 U-0 R/W-0 R/W-1 R/W-0 R/W-0 R/W-0

— — — WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN

bit 7 bit 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

bit 7-5 Unimplemented: Read as ‘0’

bit 4-1 WDTPS<3:0>: Watchdog Timer Period Select bits

Bit Value = Prescale Rate

0000 = 1:32

0001 = 1:64

0010 = 1:128

0011 = 1:256

0100 = 1:512 (Reset value)

0101 = 1:1024

0110 = 1:2048

0111 = 1:4096

1000 = 1:8192

1001 = 1:16384

1010 = 1:32768

1011 = 1:65536

1100 = Reserved

1101 = Reserved

1110 = Reserved

1111 = Reserved

bit 0 SWDTEN: Software Enable or Disable t he Watchdog Timer(1)

1 = WDT is turned on

0 = WDT is turned off (Reset value)

Note 1: If WDTE Configuration bit = 1, then WDT is always enabled, irrespective of this control bit. If WDTE

Configu ration b it = 0, then it is possible to turn WDT on/off with this control bit.

Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on:

POR, BOR

Value on

all other

Resets

WDTCON — — — WDTPS3 WDTPS2 WSTPS1 WDTPS0 SWDTEN ---0 1000 ---0 1000

OPTION_REG RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111

CONFIG CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 — —

Legend: Shaded cells are not used by the Watchdog T imer.

Note 1: See Register 12-1 f or operation of all Configuration Word register bits.

PIC16F684

12.7 Power-Down Mode (Sleep)

The Power-down mode is entered by executing a

SLEEP instruction.

If the Watchdog Timer is enabled:

• WDT will be cleared but keeps running.

•PD

bit in the STATUS register is cleared.

•TO

bit is set.

• Oscillator driver is turned off.

• I/O ports maintain the status they had before SLEEP

was executed (driving high, low or high-impedance).

For lowest current consumption in this mode, all I/O pins

should be either at V DD or VSS, with no external circuitry

drawing current from the I/O pin and the comparators

and CVREF should be disabled. I/O pins that are

high-impedance inputs should be pulled high or low

externally to avoid switching current s caused by floating

input s. The T0CKI input should also be at VDD or VSS for

lowest current consumption. The contribution from

on-chip pull-ups on PORTA should be considered.

The MCLR pin must be at a logic high level.

12.7.1 WAKE-UP FROM SLEEP

The devi ce can wake -up from Sleep through one of th e

following events:

1. External Reset input on MCLR pin.

2. Watchdog Timer wake-up (if WDT was

enabled).

3. Interrupt from RA2/INT p in, POR TA change or a

peripheral interrupt.

The firs t event wi ll cause a devic e Reset. The two latter

events are considered a continuation of program

execution. The TO and PD bits in the STATUS register

can be us ed to determine the cause o f a device R ese t.

The PD bit , whi ch i s set on pow er-u p, is clea red w hen

Sleep is invoked. TO bit is cleared if WDT wake-up

occurred.

The follo wing periph eral interrupt s can wake the device

from Sleep:

1. Timer1 interrupt. Timer1 must be operating as

an asynchronous counter.

2. ECCP Capture mode interrupt.

3. A/D conve rsion (when A/D clock source is FRC).

4. EEPROM write operation completion.

5. Comparator output changes state.

6. Interrupt-on-change.

7. External Interrupt from INT pin.

Other peripherals cannot generate interrupts since

during Sleep, no on-chip clocks are present.

When the SLEEP instruction is being executed, the next

instruction (PC + 1) is prefetched. For the device to

wake-up thro ugh an interrupt event, the co rres pon din g

interrupt enable bit must be set (enabled). Wake-up

occurs regardless of the state of the GIE bit. If the GIE

bit is clear (disabled), the device continues execution at

the ins truction a fter the SLEEP i nstructio n. If the GI E bit

is set (enabled), the device executes the instruction

after the SLEEP instruction, then branches to the inter-

rupt address (0004h). In cases where the execution of

the instruction following SLEEP is not desirable, the

user should have a NOP after the SLEEP instruction.

The WDT is cleared when the device wakes up from

Sleep, regardless of the source of wake-up.

12.7.2 WAKE-UP USING INTERRUPTS

When global interrupts are disabled (GIE cleared) and

any interrupt source has both its interrupt enable bit

and inte rrupt fla g bit s et, one of the fo llow ing wil l occur:

• If the interrupt occurs before the execution of a

SLEEP instruction, the SLEEP instruction will

comple te as a NOP. Therefore, th e WDT and WDT

prescaler and postscaler (if enabled) will not be

cleared, the TO bit will not be set and the PD bit

will not be cleared.

• If the interrupt occurs during or after the

execution of a SLEEP instruc tion, the device will

Immediately wake-up from Sleep. The SLEEP

instruction is executed. Therefore, the WDT and

WDT prescal er and pos t s ca ler (if ena bled) will be

cleared, the TO bit will be set and the PD bit will

be cleared.

Even if the flag bits were checked before executing a

SLEEP instruction, it may be possible for flag bits to

become set before the SLEEP instruct ion completes . To

determine whether a SLEEP instruction executed, test

the PD bit. If the PD bit is set, the SLEEP instruction

was executed as a NOP.

To ensure that the WDT is cleared, a CLRWDT ins truction

should be executed before a SLEEP instruction. See

Figure 12-10 for more details.

Note: It should be noted that a Reset generated

by a WDT time-out does not drive MCLR

pin low.

Note: If the g lobal interrup ts a re disa bled (G IE is

cleared ) and a ny inte rrupt so urce has both

it s interrupt enabl e bit and the corres pond-

ing interrupt flag bits set, the device will

immediately wake-up from Sleep.

PIC16F684

FIGURE 12-10: WAKE-UP FROM SLEEP THROUGH INTERRUPT

12.8 Code Protection

If the code protection bit(s) have not been

programmed, the on-chip program memory can be

read out using ICSP™ for ver ification purposes.

12.9 ID Locations

Four memory locations (2000h-2003h) are designated

as ID locations where the user can store checksum or

other code identification numbers. These locations are

not accessible during normal execution but are

readable and writable during Program/Verify mode.

Only the Least Significant 7 bits of the ID locations are

used.

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

OSC1

CLKOUT(4)

INT pin

INTF flag

(INTCON reg.)

GIE bit

(INTCON reg.)

Instruction Flow

Instruction

Fetched

Instruction

Executed

PC PC + 1 PC + 2

Inst(PC) = Sleep

Inst(PC – 1)

Inst(PC + 1)

Sleep

Processor in

Sleep

Interrupt Latency(3)

Inst(PC + 2)

Inst(PC + 1)

Inst(0004h) Inst(0005h)

Inst(0004h)

Dummy Cycle

PC + 2 0004h 0005h

Dummy Cycle

TOST(2)

PC + 2

Note 1: XT, HS or LP Oscilla tor mode assume d.

2: TOST = 1024 TOSC (drawing not to scale). This delay does not apply to EC, INTOSC and RC Oscillator modes.

3: GIE = ‘1’ assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = ‘0’, execution will continue in-line.

4: CLKOUT is not available in XT, HS, LP or EC Oscillator modes, but shown here for timing reference.

Note: The entire data EEPROM and Flash pro-

gram memory will be erased when the

code protection is turned off. See the

“PIC12F6XX/16F6XX Memory

Programming Specification” (DS41204)

for more information.

PIC16F684

12.10 In-Circuit Serial Programming

The PIC16F684 microcontrollers can be serially

progra mmed w hile in t he en d app licati on c ircuit. This i s

simply done with five connections for:

•clock

•data

• power

• ground

• programming voltage

This allows customers to manufacture boards with

unprogrammed devices and then program the micro-

controller just before shipping the product. This also

allows the most recent firmware or a custom firmware

to be programmed.

The device is placed into a Program/Verify mode by

holding the RA0 and RA1 pins low, while raising the

MCLR (VPP) pin from VIL to VIHH. See the

“PIC12F6XX/16F6XX Memory Programming

Specification” (DS41204) for more information. RA0

becomes the programming data and RA1 becomes the

programming clock. Both RA0 and RA1 are Schmitt

Trigger inputs in Program/Verify mode.

A typical In-Circuit Serial Programming connection is

shown in Figure 12-11.

FIGURE 12-11: TYPICAL IN-CIRCUIT

SERIAL PROGRAMMING

CONNECTION

12.11 In-Ci rcuit Debugger

Since in-circuit debugging requires access to three

pins, M PLAB® ICD 2 deve lo pment w ith a 1 4-pin devic e

is not practical. A special 20-pin PIC16F684 ICD device

is used with MPLAB ICD 2 to provide separate clock,

data and MCLR pins and frees all normally available

pins to the user.

A special debugging adapter allows the ICD device to

be used in place of a PIC16F684 device. The

debuggi ng adapter is the only source of th e ICD device.

When th e ICD pin on the PIC16F 684 ICD device is held

low, the In-Circuit Debugger functionality is enabled.

This function allows simple debugging functions when

used with MPL AB ICD 2. When the microc ontroller ha s

this feature enabled, some of the resources are not

available for general use. Table 12-9 shows which

features are consumed by the background debugger.

TABLE 12-9: DEBUGGER RESOURCES

For more information, see “MPLAB® ICD 2 In-Circuit

Debugger User’s Guide” (DS51331), available on

Micro c hip’s we b site (www.microchip .com) .

FIGURE 12-12: 20-PIN ICD PINOUT

External

Connector

Signals

To Normal

Connections

To Normal

Connections

PIC16F684

VDD

VSS

MCLR/VPP/RA3

RA1

RA0

+5V

VPP

CLK

Data I/O

* * *

* Isolation devices (as required)

Resource Description

I/O pins ICDCLK, ICDDATA

Stack 1 level

Program Memory Address 0h must be NOP

700h-7FFh

20-Pin PDIP

PIC16F684-ICD

In-Circuit Debug Device

ICDMCLR/VPP

VDD

RA5

RA4

RA3

ICDCLK

ICDDATA

Vss

RA0

ICD NC

RA1

RA2

RC5

RC4

RC3

RC0

RC1

RC2

PIC16F684

13.0 INSTR UCTION SET SUMMARY

The PIC 16F684 i nstructio n set i s highly orthogon al and

is comprised of three basic categories:

•Byte-oriented operations

•Bit-oriented operations

•Literal and cont rol operations

Each PIC16 instruction is a 14-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 formats for each of the categories

is presented in Figure 13-1, while the various opcode

fields are sum m ariz ed in Table 13-1.

Table 13-2 lists the instructions recognized by the

MPASMTM assembler.

For byte-oriented instructions, ‘f’ represents a file

designator. The file register designator specifies which

file register is to be used by the instruction.

The desti nation designator specifies where the result of

the operation is to be placed. If ‘d’ is zero, the result is

placed in the W regis ter . If ‘d’ is one, the res ult is place d

in the file register specified in the instruction.

For bit-oriented instructions, ‘b’ represents a bit field

designator, which selects the bit affected by the

operation, while ‘f’ represents the address of the file in

which the bit is located.

For literal and control operations, ‘k’ represents an

8-bit or 11-bit constant, or literal value.

One instr uction cycle co nsists of four os cillator periods ;

for an oscillator frequency of 4 MHz, this gives a

nominal instruction execution time of 1 μs. All

instructions are executed within a single instruction

cycle, unless a conditional test is true, or the program

counter is changed as a result of an instruction. When

this occurs, the execution takes two instruction cycles,

with the second cycle executed as a NOP.

All instruction examples use the format ‘0xhh’ to

represent a hexadecimal number, where ‘h’ signifies a

hexadecimal digit.

13.1 Read-Modify-Write Operations

Any instruction that specifies a file register as part of

the instruction performs a Read-Modify-Write (R-M-W)

operation. The register is read, the data is modified,

and the result is stored according to either the instruc-

tion, or the destination designator ‘d’. A read operation

is performed on a register even if the instruction writes

to that register.

For example, a CLRF PORTA instruction will read

PORTA, clear all the data bits , then write the result back

to PORTA. This example would have the unintended

consequence of clearing the condition that s et the RAIF

flag.

TABLE 13-1: OPCODE FIELD

DESCRIPTIONS

FIGURE 13-1: GENERAL FORMAT FOR

INSTRUCTIONS

Field Description

fRegister file address (0x00 to 0x7F)

WWorking register (accumulator)

bBit address within an 8-bit file register

kLiteral field, constant data or label

xDon’t care location (= 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.

dDestination select; d = 0: store result in W,

d = 1: store result in file register f.

Default is d = 1.

PC Program Counter

TO Time-out bit

CCarry bit

DC Digit carry bit

ZZero bit

PD Power-down bit

Byte-oriented file r e gister operations

13 8 7 6 0

d = 0 for destination W

OPCODE d f (FILE #)

d = 1 for destination f

f = 7-bit file register address

Bit-oriented file register operati ons

13 10 9 7 6 0

OPCODE b (BIT # ) f (FILE #)

b = 3-bit bit address

f = 7-bit file register address

Literal and control operations

13 8 7 0

OPCODE k (li te r a l )

k = 8-bit immediate value

13 11 10 0

OPCODE k (liter a l )

k = 11-bit immediate value

General

CALL and GOTO instructions only

PIC16F684

TABLE 13-2: PIC16F684 INSTRUCTION SET

Mnemonic,

Operands Description Cycles 14-B it Opcode Status

Affected Notes

MSb LSb

BYTE-ORIENTED FILE REGISTER OPERATIONS

ADDWF

ANDWF

CLRF

CLRW

COMF

DECF

DECFSZ

INCF

INCFSZ

IORWF

MOVF

MOVWF

NOP

RLF

RRF

SUBWF

SWAPF

XORWF

f, d

–

f, d

–

f, d

Add W and f

AND W with f

Clear f

Clear W

Complement f

Decrement f

Decrement f, Skip if 0

Increment f

Increment f, Skip if 0

Inclusive OR W with f

Move f

Move W to f

No Operation

Rotate Left f through Carry

Rotate Right f through Carry

Subtract W from f

Swap nibbles in f

Exclusive OR W with f

1(2)

0111

0101

0001

1001

0011

1011

1010

1111

0100

1000

0000

1101

1100

0010

1110

0110

dfff

lfff

0xxx

dfff

lfff

0xx0

dfff

ffff

xxxx

ffff

0000

ffff

C, DC, Z

1, 2

1, 2, 3

1, 2

1, 2, 3

1, 2

BIT-ORIENTED FILE REGISTER OPERATIONS

BCF

BSF

BTFSC

BTFSS

f, b

Bit Clear f

Bit Set f

Bit Test f, Skip if Clear

Bit Test f, Skip if Set

1 (2)

00bb

01bb

10bb

11bb

bfff

ffff

1, 2

LITERAL AND CONTROL OPERATIONS

ADDLW

ANDLW

CALL

CLRWDT

GOTO

IORLW

MOVLW

RETFIE

RETLW

RETURN

SLEEP

SUBLW

XORLW

–

Add literal and W

AND literal with W

Call Subroutine

Clear Watchdog Timer

Go to address

Inclusive OR literal with W

Move literal to W

Return from interrupt

Return with literal in W

Return from Subroutine

Go into Standby mode

Subtract W from literal

Exclusive OR literal with W

111x

1001

0kkk

0000

1kkk

1000

00xx

0000

01xx

0000

110x

1010

kkkk

0110

kkkk

0000

kkkk

0000

0110

kkkk

0100

kkkk

1001

kkkk

1000

0011

kkkk

C, DC, Z

TO, PD

C, DC, Z

Note 1: When an I/O register is modified as a function of itself (e.g., MOVF GPIO, 1), 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 to the Timer0 module.

3: If the Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second

cycle is executed as a NOP.

PIC16F684

13.2 Instruction Descripti ons

ADDLW Add literal and W

Syntax: [ label ] ADDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) + k → (W)

Status Affected: C, DC, Z

Description: The contents of the W register

are added to the eight-bit literal ‘k’

and the result is placed in the

W register.

ADDWF Add W and f

Syntax: [ label ] ADDWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) + (f) → (destination)

Status Affected: C, DC, Z

Desc ription: Add the contents o f the W re gister

with register ‘f’. If ‘d’ is ‘0’, the

result is stored in the W registe r . I f

‘d’ is ‘1’, the result is stored back

in register ‘f’.

ANDLW AND literal with W

Syntax: [ label ] ANDLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .AND. (k) → (W)

Status Affected: Z

Description: The contents of W register are

AND’ed with the eight-bit literal

‘k’. The result is placed in the W

ANDWF AND W with f

Syntax: [ label ] ANDWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .AND. (f) → (destination)

Status Affected: Z

Description: AND the W register with register

‘f’. If ‘d’ is ‘0’, the resu lt is stored in

the W register. If ‘d’ is ‘1’, the

result is sto r ed bac k in regi ste r ‘f’.

BCF Bit Clear f

Syntax: [ label ] BCF f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: 0 → (f<b>)

St at us Af fe cte d: None

Description: Bit ‘b’ in register ‘f’ is cleared.

BSF Bit Set f

Syntax: [ label ] BSF f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: 1 → (f<b>)

St at us Af fe cte d: None

Description: Bit ‘b’ in register ‘f’ is set.

BTFSC Bit Test, Skip if Clear

Syntax: [ label ] BTFSC f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b ≤ 7

Operation: skip if (f<b>) = 0

St at us Af fe cte d: None

Descr iption: If bit ‘b’ in reg ister ‘f’ is ‘1’, t he ne xt

instruction is executed.

If bit ‘b’, in register ‘f’, is ‘0’, the

next instru ction is discarde d, and

a NOP is executed instead, making

this a 2-cycle instruction.

PIC16F684

BTFSS Bit Test f, Skip if Set

Syntax: [ label ] BTFSS f,b

Operands: 0 ≤ f ≤ 127

0 ≤ b < 7

Operation: skip if (f<b>) = 1

Status Affected: None

Desc ription: If bit ‘b’ in regi ster ‘f’ is ‘0’, the ne xt

instructi on is exec uted .

If bit ‘b’ is ‘1’, then the next

instructi on is dis ca rded an d a NOP

is exec ute d i nst ead, making thi s a

2-cycle instruction.

CALL Call Subroutine

Syntax: [ label ] CALL k

Operands: 0 ≤ k ≤ 204 7

Operation: (PC)+ 1→ TOS,

k → PC<10:0>,

(PCLATH<4:3>) → PC<12:11>

Status Affected: None

Description: Call Subroutine. First, return

address (PC + 1) is pushed onto

the stack. The eleven-bit

immediate address is loaded into

PC bits <10:0>. The upper bits of

the PC are loa ded from PC LATH.

CALL is a two-cycle instruction.

CLRF Clear f

Syntax: [ label ] CLRF f

Operands: 0 ≤ f ≤ 127

Operation: 00h → (f)

1 → Z

Status Affected: Z

Desc ript ion : The con ten ts of register ‘f’ are

cleared and the Z bit is set.

CLRW Clear W

Syntax: [ label ] CLRW

Operands: None

Operation: 00h → (W)

1 → Z

Status Affected: Z

Description: W register is cleared. Zero bit (Z)

is set.

CLRWDT Clear Watchdog Timer

Syntax: [ label ] CLRWDT

Operands: None

Operation: 00h → WDT

0 → WDT prescaler,

1 → TO

1 → PD

St at us Af fe cte d: TO, PD

Description: CLRWDT instruction resets the

W atchdog T imer . It also resets the

prescaler of the WDT.

Status bits TO and PD are set.

COMF Complement f

Syntax: [ label ] COMF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) → (destination)

St at us Af fe cte d: Z

Description: The contents of register ‘f’ are

complemented. If ‘d’ is ‘0’, the

result is stored in W. If ‘d’ is ‘1’,

the result is stored back in

DECF Decrement f

Syntax: [ label ] DECF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - 1 → (destination)

St at us Af fe cte d: Z

Description: Decrement register ‘f’. If ‘d’ is ‘0’,

the result is stored in the W

stored back in register ‘f’.

PIC16F684

DECFSZ Decrement f, Skip if 0

Syntax: [ label ] DECFSZ f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - 1 → (destination);

skip if result = 0

Status Affected: None

Description: The contents of register ‘f’ are

decrem ented. If ‘d’ is ‘0’, th e result

is placed in the W register. If ‘d’ is

‘1’, the result is placed back in

If the result is ‘1’, the next

instruction is executed. If the

resu lt is ‘0’, then a NOP is

executed instead, making it a

2-cycle instruction.

GOTO Unconditional Branch

Syntax: [ label ] GOTO k

Operands: 0 ≤ k ≤ 2047

Operation: k → PC<10:0>

PCLATH<4:3> → PC<12:11>

Status Affected: None

Description: GOTO is an unconditional branch.

The e le ven -bi t im me dia t e v al ue i s

loaded into PC bits <10:0>. The

upper bits of PC are loaded from

PCLATH<4:3>. GOTO is a

two-cycle instruction.

INCF Increment f

Syntax: [ label ] INCF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) + 1 → (destination)

Status Affected: Z

Description: The contents of register ‘f’ are

incremen ted. If ‘ d’ is ‘0’, the result

is placed in the W register. If ‘d’ is

‘1’, the result is placed back in

INCFSZ Increment f, Skip if 0

Syntax: [ label ] INCFSZ f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) + 1 → (destination),

skip if result = 0

St at us Af fe cte d: None

Description: The contents of register ‘f’ are

incremented. If ‘d’ is ‘0’, the result

is placed in the W register. If ‘d’ is

‘1’, the result is placed back in

If the result is ‘1’, the next

instruction is executed. If the

result is ‘0’, a NOP is executed

instead, making it a 2-cycle

instruction.

IORLW Inclusive OR literal with W

Syntax: [ label ] IORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .OR. k → (W)

St at us Af fe cte d: Z

Descr iption: The conten ts of the W register are

OR’ed with the eight-bit literal ‘k’.

The result is placed in the

W registe r.

IORWF Inclusive OR W with f

Syntax: [ label ] IORWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .OR. (f) → (destinatio n)

St at us Af fe cte d: Z

Description: Inclusive OR the W register with

placed in the W register. If ‘d’ is

‘1’, the result is pla ce d back in

PIC16F684

MOVF Move f

Syntax: [ label ] MOVF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) → (dest)

Status Affected: Z

Description: The contents of register f is

moved to a destination dependent

upon the status of d. If d = 0,

destination is W register. If d = 1,

the destination is file register f

itsel f. d = 1 is useful to test a file

affected.

Words: 1

Cycles: 1

Example: MOVF FSR, 0

After Instruction

W= value in FSR

Z= 1

MOVLW Move literal to W

Syntax: [ label ] MOVLW k

Operands: 0 ≤ k ≤ 255

Operation: k → (W)

Status Affected: None

Desc ription: The eig ht-bit literal ‘k’ is loa ded into

W register. The “don’t cares” will

assemble a s ‘0’s.

Words: 1

Cycles: 1

Example: MOVLW 0x5A

After Instruction

W= 0x5A

MOVWF Move W to f

Syntax: [ label ] MOVWF f

Operands: 0 ≤ f ≤ 127

Operation: (W) → (f)

St at us Af fe cte d: No ne

Description: Move data from W register to

Words: 1

Cycles: 1

Example: MOVW

OPTION

Before Instruction

OPTION= 0xFF

W = 0x4F

After Instruction

OPTION= 0x4F

W = 0x4F

NOP No Operation

Syntax: [ label ] NOP

Operands: None

Operation: No operation

St at us Af fe cte d: No ne

Description: No operation.

Words: 1

Cycles: 1

Example: NOP

PIC16F684

RETFIE Return from Interrupt

Syntax: [ label ] RETFIE

Operands: None

Operation: TOS → PC,

1 → GIE

Status Affected: None

Description: Return from Interrupt. Stack is

POPed an d Top-of-S tack (T OS) is

loaded in the PC. Interrupts are

enabled by setting Global

Interrupt Enable bit, GIE

(INTCON<7>). This is a two-cycle

instruction.

Words: 1

Cycles: 2

Example: RETFIE

After Interrupt

PC = TOS

GIE = 1

RETLW Return with literal in W

Syntax: [ label ] RETLW k

Operands: 0 ≤ k ≤ 255

Operation: k → (W);

TOS → PC

St at us Af fe cte d: No ne

Description: The W register is loaded with the

eight bit literal ‘k’. The program

counter is loaded from the top of

the stack (the return address).

This is a two-cycle instruction.

Words: 1

Cycles: 2

Example:

TABLE

CALL TABLE;W contains

table

;offset value

• ;W now has table value

•

ADDWF PC ;W = offset

RETLW k1 ;Begin table

RETLW k2 ;

•

RETLW kn ; End of table

Before Instruction

W = 0x07

After Instruction

W = value of k8

RETURN Return from Subroutine

Syntax: [ label ] RETURN

Operands: None

Operation: TOS → PC

St at us Af fe cte d: None

Description: Return from subroutine. The stack

is POPed an d the top of th e s tack

(TOS) is loaded into the program

counter. This is a two-cycle

instruction.

PIC16F684

RLF Rotate Left f through Carry

Syntax: [ label ] RLF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: See description below

Status Affected: C

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 the W register.

If ‘d’ is ‘1’, the result is stored

back in register ‘f’.

Words: 1

Cycles: 1

Example: RLF REG1,0

Before Instruction

REG1 = 1110 0110

C=0

After Instruction

REG1 = 1110 0110

W = 1100 1100

C=1

RRF Rotate Right f through Carry

Syntax: [ label ] RRF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: See description below

Status Affected: C

Desc ript ion : The content s of regist e r ‘f’ are

rotat ed one bit to the r ight throug h

the Carry flag. If ‘d’ is ‘0’, the

result is placed in the W register.

If ‘d’ is ‘1’, the result is place d

back in reg ister ‘f’.

SLEEP Enter Sleep mode

Syntax: [ label ] SLEEP

Operands: None

Operation: 00h → WDT,

0 → WDT prescaler,

1 → TO,

0 → PD

St at us Af fe cte d: TO, PD

Descripti on: The power-down S tatus bit, PD is

cleared. Time-out Status bit, TO

is set. Watchdog Timer and its

prescaler are cleared.

The processor is put into Sleep

mode with th e oscillator sto pped.

SUBLW Subtract W from literal

Syntax: [ label ] SUBLW k

Operands: 0 ≤ k ≤ 255

Operation: k - (W) → (W)

Status Affected: C, DC, Z

Description: The W register is subtracted (2’s

complement method) from the

eight-bit literal ‘k’. The result is

placed in the W register.

C = 0W > k

C = 1W ≤ k

DC = 0W<3:0> > k<3:0>

DC = 1W<3:0> ≤ k<3:0>

PIC16F684

SUBWF Subtract W from f

Syntax: [ label ] SUBWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f) - (W) → (destination)

Status Affected: C, DC, Z

Description: Subtract (2’s complement method)

W register from register ‘f’. If ‘d’ is

‘0’, the result is stored in the W

stored back in register ‘f.

SWAPF Swap Nibbles in f

Syntax: [ label ] SWAPF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (f<3:0>) → (destination<7:4>),

(f<7:4>) → (destination<3:0>)

Status Affected: None

Description: The upper and lower nibbles of

‘0’, the result is placed in the W

placed in register ‘f’.

C = 0W > f

C = 1W ≤ f

DC = 0W<3:0> > f<3:0>

DC = 1W<3:0> ≤ f<3:0>

XORLW Exclusive OR literal with W

Syntax: [ label ] XORLW k

Operands: 0 ≤ k ≤ 255

Operation: (W) .XOR. k → (W)

St at us Af fe cte d: Z

Description: The contents of the W register

are XOR’ed with the eig ht-b it

literal ‘k’. The result is placed in

the W register.

XORWF Exclusive OR W with f

Syntax: [ label ] XORWF f,d

Operands: 0 ≤ f ≤ 127

d ∈ [0,1]

Operation: (W) .XOR. (f) → (destination)

St at us Af fe cte d: Z

Description: Exclusive OR the contents of the

W register with register ‘f’. If ‘d’ is

‘0’, the result is stored in the W

stored back in register ‘f’.

PIC16F684

NOTES:

PIC16F684

14.0 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 Progra mmers

- PICSTART® Plus Development Programmer

- MPLAB PM3 Device Programmer

- PICkit™ 2 Development Programmer

• Low-Cost Demonstration and Development

Boards and Evaluation Kits

14.1 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 separatel y)

- In-Circuit Deb ugger (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

• Exten si ve on-l in e 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 (eithe r asse mbly or C)

• One touch assemble (or compile) and download

to PIC MCU emulator and simulator tools

(automatically updates all project information)

• Debug us ing :

- Source files (assemb ly 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.

PIC16F684

14.2 MPASM Assembler

The MPASM Assembler is a full-featured, universal

macro assemb ler for all PIC MCUs.

The MPASM Assembler generates relocatable object

files fo r the MPLINK Ob ject Linker , Int el® standa rd 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

sour ce fil es

• Directives that allow complete control over the

assembly process

14.3 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 an d th e d sPIC 3 0 a nd ds PIC33 family of d igi t al si g-

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 info rmation tha t is optimized to the MPLAB IDE

debugger.

14.4 MPLINK Object Linker/

MPLIB Object Librari an

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 O bject Li brarian manag es the cre ation an d

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, de letion and extraction

14.5 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 linke d with other relocatable ob ject files and

arch ives to c rea te an e xecu tabl e fil e. N otabl e fe atu res

of the assembler include:

• Support for the entire dsPIC30F instruction set

• Support for fixed-point and floating-point data

• Command line interface

• Rich dire cti ve set

• Flexible macro language

• MPLAB IDE compatibility

14.6 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 periph erals and inte rnal regi sters.

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.

PIC16F684

14.7 MPLAB ICE 2000

High-Performance

In-Circui t Emu lator

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 feat ures. Interc hangeabl e proces sor modul es 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.

14.8 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 D SC® and MCU devic es. 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 pro be 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 ID E, new devic es w ill be supported,

and new features will be add ed, 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 .

14.9 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 sou rce code by s etting bre akpoi nts , singl e 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.

14.10 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 men us an d error m essages and a m odu-

lar, detachable socket assembly to support various

pack age types. The ICSP™ cable assembly is incl uded

as a standard item. In Stand-Alone mode, the MPLAB

PM3 Devic e Programmer ca n read, verif y 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 h as high-spe ed co mmunicat ions and

optimized algorithms for quick programming of large

memory devices and in corporates an SD/MMC card for

file storage and secure data applications.

PIC16F684

14.11 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

Inte grated Dev elopmen t En vironme nt so ftware 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

PIC17C76 X, may be sup ported with an a dapter socket.

The PICSTART Plus Development Programmer is CE

compliant.

14.12 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 m emory microcontrol lers. The PICkit 2 S tarter Kit

includes a prototyping development board, twelve

sequential lessons, software and HI-TECH’s PICC™

Lite C compiler , and is desig ned to hel p get up to s peed

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.

14.13 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 includ e prototyping areas for

adding custom circuitry and provide application firmware

and source code for examination and modification.

The board s suppo rt 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.

PIC16F684

15.0 ELECTRICAL SPECIFICATIONS

Absolute Maximum Ratings(†)

Ambient temperature under bias..........................................................................................................-40° to +125°C

Storage temperature........................................................................................................................ -65°C to +150°C

Vo lt a ge on VDD with respect to VSS ................................................................................................... -0.3V to +6.5V

Vo lt a ge on MCLR with respect to Vss ............................................................................................... -0.3V to +13.5V

Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V)

Total power dissipation(1) ...............................................................................................................................800 mW

Maximum curr ent o ut of VSS pin ...................................................................................................................... 95 mA

Maximum curr ent i nto VDD pin......................................................................................................................... 95 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 PORTA and PORTC (combined) ........................................................................... 90 mA

Maximum current sourced PORTA and PORTC (combined)........................................................................... 90 mA

Note 1: Power d issip ati on is calc ulated as fo llows: PDIS = VDD x {IDD – ∑ IOH} + ∑ {(VDD – VOH) x IOH} + ∑(VOl x IOL).

† 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 above maximum rating conditions for

extended periods may affect device reliability.

PIC16F684

FIGURE 15-1: PIC16F684 VOLTAGE-FREQUENCY GRAPH,

-40°C

≤

+125°C

FIGURE 15-2: HFINTOSC FREQUENCY ACCURACY OVER DEVICE VDD AND TEMPERATURE

5.5

2.0

3.5

2.5

3.0

4.0

4.5

5.0

Frequency (MHz)

VDD (V)

Note 1: The shaded region indicates the permissible combinations of voltage and frequency.

82010

125

2.0

VDD (V)

4.0 5.04.5

Temperature (°C)

2.5 3.0 3.5 5.5

± 1%

± 2%

± 5%

PIC16F684

15.1 DC Characteristics: PIC16F684-I (I ndustrial)

PIC16F684-E (Extended)

DC CHARACTERISTICS Standard Opera ting Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Unit

sConditions

D001

D001C

D001D

VDD Supply Voltage 2.0

2.0

3.0

4.5

—

5.5

FOSC < = 8 MHz: HFINTOSC, EC

FOSC < = 4 MHz

FOSC < = 10 MHz

FOSC < = 20 MHz

D002* VDR RAM Data Retention

Voltage(1) 1.5 — — V Device in Sleep mode

D003 VPOR VDD Start Voltage to

ensure internal Power-on

Reset signal

—VSS —VSee Section 12.3.1 “Power-On Reset

(POR)” for details.

D004* SVDD VDD Rise Rate to ensure

internal Power-on Reset

signal

0.05 — — V/ms See Section 12.3.1 “Power-On Reset

(POR)” for details.

* These parameters are characterized but not tested.

† Dat a i n “Typ” column i s a t 5.0 V, 25°C un less othe rw is e s t ate d. T hes e parame ters are for design gu ida nc e

only and are not tested.

Note 1: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data.

PIC16F684

15.2 DC Characteristics: PIC16F684-I (Industrial)

PIC16F684-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Device Char ac teri st ics Min Typ† Max Units Conditions

VDD Note

D010 Supply Current (IDD)(1, 2) —1116μA2.0FOSC = 32 kHz

LP Oscillator mode

—1828μA3.0

—3554μA5.0

D011* — 140 240 μA2.0F

OSC = 1 MHz

XT Oscillator mode

— 220 380 μA3.0

— 380 550 μA5.0

D012 — 260 360 μA2.0F

OSC = 4 MHz

XT Oscillator mode

— 420 650 μA3.0

—0.81.1mA5.0

D013* — 130 220 μA2.0F

OSC = 1 MHz

EC Osci llator mode

— 215 360 μA3.0

— 360 520 μA5.0

D014 — 220 340 μA2.0F

OSC = 4 MHz

EC Osci llator mode

— 375 550 μA3.0

— 0.65 1.0 mA 5.0

D015 — 8 20 μA2.0F

OSC = 31 kHz

LFINTOSC mode

—1640μA3.0

—3165μA5.0

D016* — 340 450 μA2.0F

OSC = 4 MHz

HFINTOSC mode

— 500 700 μA3.0

—0.81.2mA5.0

D017 — 410 650 μA2.0F

OSC = 8 MHz

HFINTOSC mode

— 700 950 μA3.0

— 1.30 1.65 mA 5.0

D018 — 230 400 μA2.0F

OSC = 4 MHz

EXTRC mode(3)

— 400 680 μA3.0

— 0.63 1.1 mA 5.0

D019 — 2.6 3.25 mA 4.5 FOSC = 20 MHz

HS Osci llator mode

— 2.8 3.35 mA 5.0

* These parameters are characterized but not tested.

† 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: The test con ditions for al l IDD me asurem ent s in acti ve op eration mod e are: OSC1 = e xternal s quare wav e,

from rail-to-rail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled.

2: The supply current is mainly a function of the operating voltage and frequency. Other factors, such as I/O

pin loadin g and swi tchin g rate, oscilla tor type, int erna l code exe cutio n patte rn and temp erature, al so have

an impact on the current consumption.

3: For RC oscillat or config urations, cu rrent th rough REXT i s not in cluded. The curren t through the resi stor can

be extended by the formula IR = VDD/2REXT (mA) with REXT in kΩ.

PIC16F684

15.3 DC Characteristics: PIC16F684-I (I ndustrial)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +85°C for industrial

Param

No. Device Characteristics Min Typ† Max Units Conditions

VDD Note

D020 Power-down Base

Current(IPD)(2) — 0.05 1.2 μA 2.0 WDT, BOR, Comparators, VREF and

T1OSC dis ab led

— 0.15 1.5 μA3.0

— 0.35 1.8 μA5.0

— 150 500 nA 3.0 -40°C ≤ TA ≤ +25°C

D021 — 1.0 2.2 μA 2.0 WDT Current(1)

—2.04.0μA3.0

—3.07.0μA5.0

D022 — 42 60 μA 3.0 BOR Current(1)

— 85 122 μA5.0

D023 — 32 45 μA 2.0 C omparator Current(1), both

comparators enabled

—6078μA3.0

— 120 160 μA5.0

D024 — 30 36 μA2.0CV

REF Current(1) (high range)

—4555μA3.0

—7595μA5.0

D025* — 39 47 μA2.0CV

REF Current(1) (low range)

—5972μA3.0

— 98 124 μA5.0

D026 — 4.5 7.0 μA 2.0 T1OSC Current(1), 32.768 kHz

—5.08.0μA3.0

—6.012 μA5.0

D027 — 0.30 1.6 μA 3.0 A/D Current(1), no conversion in

progress

— 0.36 1.9 μA5.0

* These parameters are characterized but not tested.

† 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: The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

2: 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.

PIC16F684

15.4 DC Characteristics: PIC16F684-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +125°C for extended

Param

No. Device Characteristics Min Typ† Max Units Conditions

VDD Note

D020E Power-down Base

Current (IPD)(2) —0.05 9 μA 2.0 WDT, BOR, Comparators, V REF and

T1OSC disabled

—0.1511 μA3.0

—0.3515 μA5.0

D021E — 1 17.5 μA 2 .0 WDT Current(1)

—219μA3.0

—322μA5.0

D022E — 42 65 μA 3.0 BOR Current(1)

—85127μA5.0

D023E — 32 45 μA 2.0 Comparator Curren t(1), both

comparators enabled

—6078μA3.0

—120160μA5.0

D024E — 30 70 μA2.0CV

REF Current(1) (high range)

—4590μA3.0

—75120μA5.0

D025E* — 39 91 μA2.0CV

REF Current(1) (low range)

—59117μA3.0

—98156μA5.0

D026E — 4.5 25 μA 2.0 T1OSC Current(1), 32.768 kHz

—530μA3.0

—640μA5.0

D027E — 0.30 12 μA 3 .0 A/D Current(1), no conversio n in

progress

—0.3616 μA5.0

* These parameters are characterized but not tested.

† 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: The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this

peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD

current from this limit. Max values should be used when calculating total current consumption.

2: 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.

PIC16F684

15.5 DC Characteristics: PIC16F684-I (Industrial)

PIC16F684-E (Extended)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +8 5°C for industr ial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Units Conditions

VIL Input Low Voltage

I/O Port:

D030 with TTL buffer Vss — 0.8 V 4.5V ≤ VDD ≤ 5.5V

D030A Vss — 0.15 VDD V2.0V ≤ VDD ≤ 4.5V

D031 with Schmitt Trigger buf fer Vss — 0.2 VDD V2.0V ≤ VDD ≤ 5.5V

D032 MCLR, OSC1 (RC mode)(1) VSS —0.2 VDD V

D033 OSC1 (XT and LP modes) VSS —0.3V

D033A OSC1 (HS mode) VSS —0.3 VDD V

VIH Input High Voltage

I/O ports: —

D040 with TTL buffer 2.0 — VDD V4.5V ≤ VDD ≤ 5.5V

D040A 0.25 VDD + 0.8 — VDD V2.0V ≤ VDD ≤ 4.5V

D041 with Schmitt Trigger buffer 0.8 VDD —VDD V2.0V ≤ VDD ≤ 5.5V

D042 MCLR 0.8 VDD —VDD V

D043 OSC1 (XT and LP modes) 1.6 — VDD V

D043A OSC1 (HS mode) 0.7 VDD —VDD V

D043B OSC1 (RC mode) 0.9 VDD —VDD V(Note 1)

IIL Input Leakage Current(2)

D060 I/O ports — ± 0.1 ± 1μAVSS ≤ VPIN ≤ VDD,

Pin at high-impedance

D061 MCLR(3) —± 0.1 ± 5μAVSS ≤ VPIN ≤ VDD

D063 OSC1 — ± 0.1 ± 5μAVSS ≤ VPIN ≤ VDD, XT, HS and

LP oscillator configuration

D070* IPUR PORTA Weak Pull-up Current 50 250 400 μAVDD = 5.0V, VPIN = VSS

VOL Output Low Voltage(5)

D080 I/O ports — — 0.6 V IOL = 8.5 mA, VDD = 4.5V (Ind.)

VOH Output High Voltage(5)

D090 I/O ports VDD – 0.7 — — V IOH = -3.0 mA, VDD = 4.5V (Ind.)

* These parameters are charact erized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are

no t te sted.

Note 1: In RC oscill ator configuration, the O SC1/ CLKIN pin is a Schmitt Trigger input. It is not recommended to use an external

clock in RC mode.

2: Negative current is defined as current sourced by the pin.

3: 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.

4: See Section 10.4.1 “Using the Data EEPROM” for additional information.

5: Including OSC2 in CLKOUT mode.

PIC16F684

D100 IULP Ultra Low-Power Wake-Up

Current — 200 — nA S ee Application Note AN879,

“Using the Microchip Ultra

Low-Power Wake-up Module”

(DS00879)

Capacitive Loading Specs on

Output Pins

D101* COSC2 OSC2 pin — — 15 pF In XT, HS and LP modes when

external clock is used to drive

OSC1

D101A* CIO All I/O pins — — 50 pF

Data EEPROM Memory

D120 EDByte Endurance 100K 1 M — E/W -40°C ≤ TA ≤ +85°C

D120A EDByte Endurance 10K 100K — E/W +85°C ≤ TA ≤ +125°C

D121 VDRW VDD for Read/Write VMIN — 5.5 V Using EECON1 to read/write

VMIN = Minimum operating

voltage

D122 TDEW Erase/Write Cycle Time — 5 6 ms

D123 TRETD Characteristic Retention 40 — — Y ear Pro vid e d n o ot her sp ec i fi c a ti on s

are violated

D124 TREF Number of Total Erase/Write

Cycles before Refresh(4) 1M 10M — E/W -40°C ≤ TA ≤ +85°C

Program Flash Memory

D130 EPCell Endurance 10K 100K — E/W -40°C ≤ TA ≤ +85°C

D130A EDCell Endurance 1K 10K — E/W +85°C ≤ TA ≤ +125°C

D131 VPR VDD for Read VMIN —5.5VVMIN = Minimum operating

voltage

D132 VPEW VDD for Erase/Write 4.5 — 5.5 V

D133 TPEW Erase/Write cycle time — 2 2.5 ms

D134 TRETD Characteristic Retention 40 — — Y ear Pro vid e d n o ot her sp ec i fi c a ti on s

are violated

15.5 DC Characteristics: PIC16F684-I (Industrial)

PIC16F684-E (Extended) (Continued)

DC CHARACTERISTICS Standard Operating Conditions (unless otherwise stated)

Operating temperature -40°C ≤ TA ≤ +8 5°C for industr ial

-40°C ≤ TA ≤ +125°C for extended

Param

No. Sym Characteristic Min Typ† Max Units Conditions

* These parameters are charact erized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are

no t te sted.

Note 1: In RC oscill ator configuration, the OSC1/CLKIN pin is a Schmitt T rigger input. It is not recommended to use an external

clock in RC mode.

2: Negative current is defined as current sourced by the pin.

3: 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.

4: See Section 10.4.1 “Using the Data EEPROM” for additional information.

5: Including OSC2 in CLKOUT mode.

PIC16F684

15.6 Thermal Considerations

Standard Operating Conditions (unless otherwise stated)

Ope rati ng temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Typ Units Conditions

TH01 θJA Thermal Resistance

Junction to Ambient 69.8 C/W 1 4-pin PDIP package

85.0 C/W 14-pin S OIC package

100.4 C/W 1 4-pin TSS OP package

46.3 C/W 16- pin QFN 4x0.9mm package

TH02 θJC Thermal Resistance

Junction to Case 32.5 C/W 14-pin PDIP pac kage

31.0 C/W 14-pin S OIC package

31.7 C/ W 14- pin TSSOP package

2.6 C/W 16-pin QFN 4x0 .9mm package

TH03 TJJunction Temperature 150 C For derated power calculations

TH04 PD Power Dissipation — W PD = PINTERNAL + PI/O

TH05 PINTERNAL Internal Power Dissipation — W PINTERNAL = IDD x VDD

(NOTE 1)

TH06 PI/OI/O Power Dissipation — W PI/O = Σ (IOL * V OL) + Σ (IOH * (VDD - VOH))

TH07 PDER Derated Power — W PDER = (TJ - TA)/θJA

(NOTE 2, 3)

Note 1: IDD is current to run the chip alone without driving any load on the output pins.

2: TA = Ambient Temperature.

3: Maximum allowable power dissipation is the lower value of either the absolute maximum total power

dissipation or derated power (PDER).

PIC16F684

15.7 Timing Parameter Symbology

The timing parameter symbols have been created with

one of the following formats:

FIGURE 15-3: LOAD CONDITIONS

1. TppS2ppS

2. TppS

TF Frequency T Time

Lowercase letters (pp) and their meanings:

cc CCP1 osc OSC1

ck CLKOUT 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 T1CKI

mc MCLR wr WR

Uppe rcase letters and th eir meanings:

SFFall PPeriod

HHigh RRise

I Invalid (High-impedance) V Valid

L Low Z High-impedance

Legend: CL= 50 pF for all pins

15 pF for OSC2 output

Load Con dition

PIC16F684

15.8 AC Characteri stics: PIC16F684 (Industrial , Extended)

FIGURE 15-4: CLOCK TIMING

TABLE 15-1: CLOCK OSCILLATOR TIMING REQUIREMENTS

Standard Operating Condi tions (unless o th erwise stated)

Operat i ng t em peratur e -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

OS01 FOSC Externa l CLKIN Freq uency(1) DC — 37 kH z LP O scillator m ode

DC — 4 MHz XT Oscillator mode

DC — 20 MHz HS Oscillator mode

DC — 20 MHz EC Oscillator mode

Oscillator Frequency(1) — 32. 76 8 — kHz LP Oscillator m ode

0.1 — 4 M Hz XT Oscillator mode

1 — 20 MHz HS Oscillator mode

DC — 4 MHz RC Oscillator mode

OS02 TOSC External CLKIN Period(1) 27 — • μs LP Osci llator m ode

250 — • ns XT Oscillator mode

50 — • ns HS O sc illat or mode

50 — • ns EC O sc illat or mode

Oscillator Period(1) —30.5— μs LP Oscillator m ode

250 — 10,000 ns XT Oscillator m ode

50 — 1,0 00 ns HS Oscillator mo de

250 — — ns RC Oscillator mode

OS03 TCY Inst ruction C ycle Time(1) 200 TCY DC ns TCY = 4/FOSC

OS04* TosH,

TosL External CLKIN High,

External CLKIN Low 2——μs LP oscillator

100 — — ns XT oscillator

20 — — ns HS osc illat or

OS05* TosR,

TosF External CLKIN Rise,

External CLKIN Fall 0 — • ns LP oscillator

0 — • ns XT oscillator

0 — • ns HS osci llator

* These paramet ers are characterized but no t test e d.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance only and

are no t t ested.

Note 1: I nstru ct io n cycle pe ri od (TCY) equ als fo ur tim es the input oscillator t ime base period. All specified values are

based on chara ct er iz at ion data for that particul ar oscilla to r type un d er standard ope rating con di tio ns w i t h th e

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 OSC 1 pi n. W hen an exte rn al clock input is used, the ‘max’ cycl e tim e li m it is ‘DC’ (no clock) for all

devices.

OSC1/CLKIN

OSC2/CLKOUT

Q4 Q1 Q2 Q3 Q4 Q1

OS02

OS03OS04 OS04

OSC2/CLKOUT

(LP,XT,HS Mod es)

(CLKOUT Mode)

PIC16F684

TABLE 15-2: OSCILLATOR PARAMETERS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Freq

Tolerance Min Typ† Max Units Conditions

OS06 TWARM Internal Oscillator Switch

when running(3) ———2TOSC S l owest clock

OS07 TSC Fail-Safe Sample Clock

Period(1) ——21—msLFINTOSC/64

OS08 HFOSC Internal Calibrated

HFINTOSC Frequency(2) ±1% 7.92 8.0 8.08 MHz VDD = 3.5V, 25°C

±2% 7.84 8.0 8.16 MHz 2.5V ≤ VDD ≤ 5.5V,

0°C ≤ TA ≤ +85°C

±5% 7.60 8.0 8.40 MHz 2.0V ≤ VDD ≤ 5.5V,

-40°C ≤ TA ≤ +85°C (Ind.),

-40°C ≤ TA ≤ +125°C (Ext.)

OS09* LFOSC Internal Uncalibra ted

LFINTOSC Frequency — 153145kHz

OS10* TIOSC

ST HFINTOSC Oscillator

W ake-up from Sleep

Start-up Time

— 5.5 12 24 μsVDD = 2.0V, -40°C to +85°C

—3.5714μsVDD = 3.0V, -40°C to +85°C

—3611μsV

DD = 5.0V, -40°C to +85°C

* These parameters are characterized but not tested.

† Data in ‘Typ’ column i s at 5.0V, 25°C unl es s ot her w i se stated. These paramet er s are for desig n guidance only

and are not test ed.

Note 1: Ins t r uction cycl e period (TCY) equals four times the input oscillator time base period. All specified values are

based on characterization data for that particular oscillator type under standard operating conditions with the

device e xecuting co de. Exceedi ng these specified lim its ma y r esult in an unstab le oscillator operation and /o r

higher tha n expected current co nsumpti on . All devices are tes te d t o operate at ‘mi n’ values with an external

clock applied to th e OSC1 pin. When an extern al clo ck in put is used, th e ‘max’ cyc le time l imit is ‘DC’ (n o clo ck)

for all devi ces .

2: To ensure these oscillator frequency tolerances, VDD and VSS mu st be capacitivel y decoupl ed as close t o th e

device a s possible. 0. 1 μF and 0.01 μF valu es in paral le l are r ecommended.

3: By design .

PIC16F684

FIGURE 15-5: CLKOUT AND I/O TIMING

Fosc

CLKOUT

I/O pi n

(Input)

I/O pin

(Output)

Q4 Q1 Q2 Q3

OS11

OS19

OS13

OS15

OS18, OS19

OS20

OS21

OS17 OS16

OS14

OS12

OS18

Old Value New Value

Write Fetch Read ExecuteCycle

TABLE 15-3: CLKOUT AND I/O TIMING PARAMETERS

Standard Operating Conditi ons (unle ss otherw is e stated )

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

OS11 TOSH2CKLFOSC↑ to CLKOUT↓ (1) — — 70 ns VDD = 5.0V

OS12 TOSH2CKHFOSC↑ to CLKOUT↑ (1) — — 72 ns VDD = 5.0V

OS13 TCKL2IOVCLKOUT↓ to Port out valid(1) — — 20 ns

OS14 TIOV2CKH Port input valid before CLKOUT↑(1) TOSC + 200 ns — — ns

OS15 TOSH2IOVFOSC↑ (Q1 cycle) to Port out valid — 50 70* ns VDD = 5.0V

OS16 TOSH2IOIFOSC↑ (Q2 cycle) to Port input invalid

(I/O in hold time) 50 — — ns VDD = 5.0V

OS17 TIOV2OSH Port input valid to FOSC↑ (Q2 cycle)

(I/O in setup time) 20 — — ns

OS18 TIOR Port output rise time(2) —

—15

40 72

32 ns VDD = 2.0V

VDD = 5.0V

OS19 TIOF Port output fall time(2) —

—28

15 55

30 ns VDD = 2.0V

VDD = 5.0V

OS20* TINP INT pin input high or low time 25 — — ns

OS21* TRAP PORT A interrupt-on-change new input

level time TCY ——ns

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated.

Note 1: Measurements are taken in RC mode where CLKOUT output is 4 x TOSC.

2: Includes OSC2 in CLKOUT mode.

PIC16F684

FIGURE 15-6: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND

POWER-UP TIMER TIMING

FIGURE 15-7: BROW N-OUT RESET TIMING AND CHARACTERISTICS

VDD

MCLR

Internal

POR

PWRT

Time-out

OSC

Start-Up Time

Internal Reset(1)

Wat c hdog Timer

I/O pins

Note 1: Asserted low.

Reset(1)

VBOR

VDD

(Device in Brown-out Reset) (Device not in Brown-out Reset)

33*

* 64 ms delay only if PWRTE bit in the Configuration Word register is programmed to ‘0’.

Reset

(due to BOR)

VBOR + VHYST

PIC16F684

TABLE 15-4: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER

AND BROWN-OUT RESET PARAMETERS

Standard Operating Conditi ons (unle ss otherw is e stated )

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

30 TMCLMCLR Pulse Width (low) 2

5—

——

—μs

μsVDD = 5V, -40°C to +85°C

VDD = 5V

31 TWDT Wa tchdog Timer Time-out

Period (No Prescaler) 10

10 16

16 29

31 ms

ms VDD = 5V, -40°C to +85°C

VDD = 5V

32 TOST Oscillation Start-up Timer

Period(1, 2) — 1024 — TOSC (NOTE 3)

33* TPWRT Power-up Timer Period 40 65 140 ms

34* TIOZ I/O High-impedance from

MCLR Low or Watchdog Timer

Reset

——2.0μs

35 VBOR Brown-out Reset Voltage 2.0 — 2.2 V (NOTE 4)

36* VHYST Brown-out Reset Hysteresis — 50 — mV

37* TBOR Brown- out Reset Minimum

Detection Period 100 — — μsVDD ≤ VBOR

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note 1: Instructi on cycle period (TCY) equals four times the input oscillator time base period. All specified values

are based on charac teri za tion data for that part ic ular oscillator typ e unde r st andard operating con di tion s

with the device executing code. Exceeding these specified limits may result in an unstable oscillator oper-

ation and/or higher than expected current consumption. All devices are tested to operate at ‘min’ values

with an external clock applied to the OSC1 pin. When an external clock input is used, the ‘max’ cycle time

limit is ‘DC’ (no clock) for all devices.

2: By design.

3: Period of the slow er clock.

4: To ensure thes e voltag e toleranc es, VDD and VSS must b e capa citively deco upled as c lose to th e device as

possible. 0.1 μF and 0.01 μF values in parallel are recommended.

PIC16F684

FIGURE 15-8: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS

TABLE 15-5: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS

Standard Operating Conditions (unless otherwise stated)

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

40* TT0H T0CKI High Pulse Width No Prescaler 0.5 TCY + 20 — — ns

With Prescaler 10 — — ns

41* TT0L T 0CK I Low Pulse Width No Presca ler 0.5 TCY + 20 — — ns

With Prescaler 10 — — ns

42* TT0P T0CK I Period Greater of:

20 or TCY + 40

— — ns N = prescale value

(2, 4, ..., 256)

45* TT1H T1CKI High

Time Synchronous, No Prescaler 0.5 TCY + 20 — — ns

Synchronous,

with Pr escaler 15 — — ns

Asynchronous 30 — — ns

46* TT1L T 1CK I Low

Time Synchronous, No Prescaler 0.5 TCY + 20 — — ns

Synchronous,

with Pr escaler 15 — — ns

Asynchronous 30 — — ns

47* TT1P T1CKI Input

Period Synchronous Greater of:

30 or TCY + 40

— — ns N = prescale value

(1, 2, 4, 8)

Asynchronous 60 — — ns

48 FT1 Timer1 Oscillator Input Frequency Range

(oscillator enabled by setting bit T1OSCEN) — 32.768 — kHz

49* TCKEZTMR1 Delay from External Clock Edge to Ti mer

Increment 2 TOSC —7 TOSC — Timers in Sync

mode

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These p arameters are for design guidance only and are not

tested.

T0CKI

T1CKI

40 41

45 46

47 49

TMR0 or

TMR1

PIC16F684

FIGURE 15-9: CAPTURE/COMPARE/PWM T IMINGS (ECCP)

TABLE 15-6: CAPTURE/COMPARE/PWM REQUIREMENTS (ECCP)

Standard Operating Conditi ons (unle ss otherw is e stated )

Operating Temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

CC01* TccL CCP1 Input Low Time No Prescaler 0.5TCY + 20 — — ns

With Prescaler 20 — — ns

CC02* TccH CCP1 Input High Time No Prescaler 0.5TCY + 20 — — ns

With Prescaler 20 — — ns

CC03* TccP CCP1 Input Period 3TCY + 40

N— — ns N = prescale

value (1, 4 or

16)

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested .

Note: Refer to Figure 15-3 for load conditions.

(Capture mode)

CC01 CC02

CC03

CCP1

PIC16F684

TABLE 15-7: COMPARATOR SPECIFICATIONS

TABLE 15-8: COMPARATOR VOLTAGE REFERENCE (CVREF) SPECIFICATIONS

Standard Operating Conditions (unless otherwise stated)

Operati ng Tem per ature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristics Min Typ† Max Units Comments

CM01 VOS Input Offset Voltage — ± 5.0 ± 10 mV (VDD - 1.5)/2

CM02 VCM Input Common Mode Voltage 0 — V DD – 1.5 V

CM03* CMRR Common Mode Rejection Ratio +55 — — dB

CM04* TRT Response Time Falling — 150 600 ns (NOTE 1)

Rising — 200 1000 ns

CM05* TMC2COV Comparator Mode Change to

Output Valid —— 10 μs

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design guidance

only and are not tested.

Note 1: Respons e tim e is meas ured wi th one comp arator input at (VDD - 1.5)/2 - 100 mV to (VDD -1.5)/2+20mV.

S tandard Operating Conditi ons (unle ss othe rwis e stated)

Operati ng tem pera ture -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristics Min Typ† Max Units Comments

CV01* CLSB Step Size(2) —

—VDD/24

VDD/32 —

—V

VLow Range (VRR = 1)

High Range (VRR = 0)

CV02* CACC Absolute Accuracy —

——

—± 1/2

± 1/2 LSb

LSb Low Range (VRR = 1)

High Range (VRR = 0)

CV03* CRUnit Resistor Value (R) — 2k — Ω

CV04* CST Se ttli ng Time(1) ——10μs

* These parameters are characterized but not tested.

† Data in ‘Typ’ column is at 5V, 25°C unless otherwise stated. These parameters are for design

guidance only and are not tested.

Note 1: Settling time measured while VRR = 1 and VR<3:0> transitions from ‘0000’ to ‘1111’.

2: See Section 8.10 “Compa rator Voltage Reference” for more information.

PIC16F684

TABLE 15-9: PIC16F684 A/D CONVERTER (ADC) CHARACTERISTICS

Standard Operating Conditions (unless otherwise stated)

Ope rati ng temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

AD01 NRResolution — — 10 bits bit

AD02 EIL Integral Error — — ±1LSbVREF = 5.12V

AD03 EDL Differential Error — — ±1 LSb No missing codes to 10 bits

VREF = 5.12V

AD04 EOFF Offset Error — — ±1LSbVREF = 5.12V

AD07 EGN Gain Error — — ±1LSbVREF = 5.12V

AD06

AD06A VREF Reference Voltage(3) 2.2

2.7 ——

VDD VAbsolute minimum to ensure 1 LSb

accuracy

AD07 VAIN Full-Scale Range VSS —VREF V

AD08 ZAIN Recommended

Impedance of Analog

Voltage Source

—— 10kΩ

AD09* IREF VREF Input Current(3) 10 — 1000 μADuring VAIN acquisition.

Based on differential of VHOLD to VAIN.

—— 50μA During A/D conversion cyc le.

* These parameters are characterized but not tested.

† 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: Total Absolute Error includes integral, differential, offset and gain errors.

2: The A/D conversion result never decreases with an increase in the input voltage and has no missing

codes.

3: ADC VREF is from external VREF or VDD pin, whichever is selected as reference input.

4: When ADC is off, it will not consume any current other than leakage current. The power-down current

specific ati on inc lu des any suc h leakage from the AD C module.

PIC16F684

TABLE 15-10: PIC16F684 A/D CONVERSION REQUIREMENTS

Standard Operating Conditions (unless otherwise stated)

Ope rati ng temperature -40°C ≤ TA ≤ +125°C

Param

No. Sym Characteristic Min Typ† Max Units Conditions

AD130* TAD A/D Clock Perio d 1.6 — 9.0 μsTOSC-based, VREF ≥ 3.0V

3.0 — 9.0 μsTOSC-b ased, VREF full range

A/D Internal RC

Oscillator Period 3.0 6.0 9.0 μsADCS<1:0> = 11 (ADRC mode)

At V DD = 2.5V

1.6 4.0 6.0 μsAt VDD = 5.0V

AD131 TCNV Conversion Time

(not includin g

Acquisiti on Time)(1)

—11—TAD Set GO/DONE bit t o new data in A/D

Result register

AD132* TACQ Acquisition Tim e 11.5 — μs

AD133* TAMP Amplifier Settling Time — — 5 μs

AD134 TGO Q4 to A/D Clock Start —

—

TOSC/2

TOSC/2 + TCY

—

— If the A/D clock source is selected as

RC, a time of TCY is added before the

A/D clock st art s. This allo ws the SLEEP

instruction to be executed.

* These parameters are characterized but not tested.

† 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: ADRESH and ADRESL registers may be read on the following TCY cycle.

2: See Section 9.3 “A/D Acquisition Requirements” for minimum conditions.

PIC16F684

FIGURE 15-10: PIC16F684 A/D CONVERSION TIMING (NORMAL MODE)

FIGURE 15-11: PIC16F684 A/D CONVERSION TIMING (SLEEP MODE)

AD131

AD130

BSF ADCON0, GO

A/D CLK

A/D Data

ADRES

ADIF

Sample

OLD_DATA

Sampling Stopped

DONE

NEW_DATA

987 3210

Note 1: If t he A/D clock source is s elected as R C, a time of TCY is added before the A/D clock starts. This allows the

SLEEP instruction to be executed.

1 TCY

AD134 (TOSC/2(1))

1 TCY

AD132

AD131

AD130

BSF ADCON0, GO

A/D CLK

A/D Data

ADRES

ADIF

Sample

OLD_DATA

Sampling Stopped

DONE

NEW_DATA

9 7 3210

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.

AD134

1 TCY

(TOSC/2 + TCY(1))

1 TCY

PIC16F684

NOTES:

PIC16F684

16.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES

The graphs and tables provided in this section are for design guidance and are not tested.

In some graphs or tables, the data presented are outside specified operating range (i.e., outside specified VDD

range). This is for information only and devices are ensured to operate properly only within the specified range.

“Typical” represents the mean of the distribution at 25°C. “Maximum” or “minimum” represents

(mean + 3σ) or (mean - 3σ) respectively , where σ is a st andard deviation, over each temperature range.

FIGURE 16-1: TYPICAL IDD vs. FOSC OVER VDD (EC MODE)

Note: The graphs and tables provided following this note are a statistical summary based on a limited number of

samples and are provided for informational purposes only . The performance characteristics listed herein are

not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified

operating range (e.g., outside specified power supply range) and therefore, outside the warranted range.

3.0V

4.0V

5.0V

5.5V

2.0V

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

1 MHz 2 MHz 4 MHz 6 MHz 8 MHz 10 MHz 12 MH z 14 MHz 16 MHz 18 MHz 20 MHz

FOSC

IDD (mA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Tem p) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-2: MAXIMU M IDD vs. FOSC OVER VDD (EC MODE)

FIGURE 16-3: TYPICAL IDD vs. FOSC OVER VDD (HS MODE)

EC Mode

3.0V

4.0V

5.0V

2.0V

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

1 MHz 2 MHz 4 MHz 6 MHz 8 MHz 10 MHz 12 MHz 14 MHz 16 MHz 18 MHz 20 MHz

FOSC

IDD (mA)

5.5V

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Tem p) + 3σ

(-40°C to 125°C)

Typical IDD vs FOSC Over Vdd

HS Mode

3.0V

3.5V

4.0V

4.5V

5.0V

5.5V

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4 MHz 10 MHz 16 MHz 20 MHz

FOSC

IDD (mA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-4: MAXIMU M IDD vs. FOSC OVER VDD (HS MODE)

FIGURE 16-5: TYPICAL IDD vs. VDD OVER FOSC (XT MODE)

Maximum IDD vs FOSC Over Vdd

HS Mode

3.5V

4.0V

4.5V

5.0V

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

4 MHz 10 MHz 16 MHz 20 MHz

FOSC

IDD (mA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

3.0V

5.5V

XT Mode

100

200

300

400

500

600

700

800

900

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

4 MHz

1 MHz

PIC16F684

FIGURE 16-6: MAXIMU M IDD vs. VDD OVER FOSC (XT MODE)

FIGURE 16-7: TYPICAL IDD vs. VDD OVER FOSC (EXTRC MODE)

XT Mode

200

400

600

800

1,000

1,200

1,400

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

4 MHz

1 MHz

EXTRC Mode

100

200

300

400

500

600

700

800

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IDD (μA)

1 MHz

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

4 MHz

PIC16F684

FIGURE 16-8: MAXIMU M IDD vs. VDD OVER FOSC (EXTRC MODE)

FIGURE 16-9: IDD vs. VDD OVER FOSC (L FINT OSC MODE, 31 kHz)

EXTRC Mode

200

400

600

800

1,000

1,200

1,400

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mea n (Wors t Case Temp) + 3σ

(-40°C to 125°C)

4 MHz

1 MHz

LFINTOSC Mode, 31KHZ

Typical

Maximum

VDD (V)

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

PIC16F684

FIGURE 16-10 : IDD vs. VDD OVER FOSC (LP MODE)

FIGURE 16-11: TYPICAL IDD vs. FOSC OVER VDD (HFINTOSC MODE)

LP Mode

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mea n (Wors t Case Temp) + 3σ

(-40°C to 125°C)

32 kHz Maximum

32 kHz Typical

HFINTOSC

2.0V

3.0V

4.0V

5.0V

5.5V

200

400

600

800

1,000

1,200

1,400

1,600

125 kHz 250 kHz 500 kHz 1 MHz 2 MHz 4 MHz 8 MHz

FOSC

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-12 : MAXIMUM IDD vs. FOSC OVER VDD (HFINTOSC MODE)

FIGURE 16-13: TYPICAL IPD vs. VDD (SLEEP MODE, ALL PERIPHERALS DISABLED)

HFINTOSC

2.0V

3.0V

4.0V

5.0V

5.5V

200

400

600

800

1,000

1,200

1,400

1,600

1,800

2,000

125 kHz 250 kHz 500 kHz 1 MHz 2 MHz 4 MHz 8 MHz

FOSC

IDD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Wors t Case Temp) + 3σ

(-40°C to 125°C)

Typical

(Sleep Mode all Peripherals Disabled)

0.0

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst C ase Tem p) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-14 : MAXIMUM IPD vs. VDD (SLEEP MODE, ALL PERIPHERALS DISABLED)

FIGURE 16-15 : COMPARATOR IPD vs. VDD (BOTH COMPARATORS ENABLED)

Maximum

(Sleep Mode all Peripherals Disabled)

Max. 125°C

Max. 85°C

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Maximum: Mean + 3σ

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

100

120

140

160

180

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Maximum

Typical

Typical: Statistical Mean @25°C

Maximum: Mean (Wors t Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-16 : BOR IPD vs. VDD OV ER TEMPER ATURE

FIGURE 16-17: TYPICAL WDT IPD vs. VDD OVER TEMPERATURE

100

120

140

160

2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Typical: Statistical Mean @25°C

Maximu m: Mean (Wor st Case Temp) + 3σ

(-40°C to 125°C)

Maximum

Typical

0.0

0.5

1.0

1.5

2.0

2.5

3.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-18: MAXIMUM WDT IPD vs. VDD OVER TEMPERATURE

FIGURE 16-19 : WDT PERIOD vs. VDD OVER TEMPERATURE

Maximum

Max. 125°C

Max. 85°C

0.0

5.0

10.0

15.0

20.0

25.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Typical: Statistical Mean @25°C

Maximum: Mean (Wors t Case Temp) + 3σ

(-40°C to 125°C)

Minimum

Typical

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Time (ms)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C) Max. (125°C)

Max. (85°C)

PIC16F684

FIGURE 16-20: WDT PERIOD vs. TEMPERATURE OVER VDD (5.0V)

FIGURE 16-21 : CVREF IPD vs. VDD OVER TEMPERATURE (HIGH RANGE)

Vdd = 5V

-40°C 25°C 85°C 125°C

Temperature (°C)

Time (ms)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

Maximum

Typical

Minimum

High Range

Typical

Max. 85°C

100

120

140

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Max. 125°C

Typical: Statistical Mean @25°C

Maximum: Me an (Wors t Case Temp) + 3 σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-22 : CVREF IPD vs. VDD OVER TEMPERATURE (LOW RANGE)

FIGURE 16-23 : VOL vs. IOL OVER TEMPERATURE (VDD = 3.0V)

Typical

Max. 85°C

100

120

140

160

180

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (μA)

Max. 125°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

(VDD = 3V, -40×C TO 125×C)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

IOL (m A)

VOL (V)

Max. 85°C

Max. 125°C

Typical 25°C

Min. -40°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-24 : VOL vs. IOL OVER TEMPERATURE (VDD = 5.0V)

FIGURE 16-25 : VOH vs. IOH OVER TEMPERATURE (VDD = 3.0V)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 10.0

IOL (mA)

VOL (V)

Typical: Statistical Mean @25×C

Maximum: Meas + 3 (-40×C to 125×C)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

Max. 85°C

Typ. 25°C

Min. -40°C

Max. 125°C

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

-4.0-3.5-3.0-2.5-2.0-1.5-1.0-0.50.0 IOH (mA)

VOH (V)

Typ. 25°C

Max. -40°C

Min. 125°C

Typical: Statistical Mean @25°C

Maximum: Mean (W orst C ase Tem p) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-26 : VOH vs. IOH OVER TEMPERATURE (VDD = 5.0V)

FIGURE 16-27: TTL INPUT THRESHOLD VIN vs. VDD OVER TEMPERATURE

(VDD = 5V, -40×C TO 125×C)

3.0

3.5

4.0

4.5

5.0

5.5

-5.0-4.5-4.0-3.5-3.0-2.5-2.0-1.5-1.0-0.50.0 IOH (mA)

VOH (V)

Max. -40°C

Typ. 25°C

Min. 125°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

(TTL Input, -40×C TO 125×C)

0.5

0.7

0.9

1.1

1.3

1.5

1.7

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

VIN (V)

Typ. 25°C

Max. -40°C

Min. 125°C

Typical: Statistical Mean @25°C

Maximum: Mean (Wors t Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-28: SCHMITT TRIGGER INPUT THRESHOLD VIN vs. VDD OVER TEMPER ATURE

FIGURE 16-29 : T1OSC IPD vs. VDD OVER TEMPERATURE (32 kHz)

(ST Input, -40×C TO 125×C)

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

VIN (V)

VIH Max. 125°C

VIH Min. -40°C

VIL Min. 125°C

VIL Max. -40°C

Typical: Statistical Mean @25°C

Maximum: Mean (Wors t Case Temp) + 3σ

(-40°C to 125°C)

Typ. 25°C

Max. 85°C

Max. 125°C

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

IPD (mA)

Maximum: Mean + 3 (-40×C to 125×C)

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-30: COMPARATOR RESPONSE TIME (R ISING EDGE)

FIGURE 16-31: COMPARATOR RESPONSE TIME (FALLING EDGE)

531 806

100

200

300

400

500

600

700

800

900

1000

2.0 2.5 4.0 5.5

VDD (V)

Response Time (nS)

Max. 85°C

Typ. 25°C

Min. -40°C

Max. 125°C

Note:

V- input = Transition from VCM + 100MV to VCM - 20MV

V+ input = VCM

VCM = VDD - 1.5V)/2

100

200

300

400

500

600

700

800

900

1000

2.0 2.5 4.0 5.5

VDD (V)

Response Time (nS)

Max. 85°C

Typ. 25°C

Min. -40°C

Max. 125°C

Note:

V- input = Transition from VCM - 100MV to VCM + 20MV

V+ input = VCM

VCM = VDD - 1.5V)/2

PIC16F684

FIGURE 16-32: LFINTOSC FREQUENCY vs. VDD OVER TEMPERATURE (31 kHz)

FIGURE 16-33: ADC CLOCK PERIOD vs. VDD OVER TEMPERATURE

LFINTOSC 31Khz

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Frequency (Hz)

Max. -40°C

Typ. 25°C

Min. 85°C

Min. 125°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Time (μs)

25°C

85°C

125°C

-40°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-34: TYPICAL HFINTOSC START-UP TIMES vs. VDD OVER TEMPERATURE

FIGURE 16-35: MAXIMUM HFINTOSC START-UP TIMES vs. VDD OVER TEMPERATURE

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Time (μs)

85°C

25°C

-40°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

-40C to +85C

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Time (μs)

-40°C

85°C

25°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

PIC16F684

FIGURE 16-36: MINIMUM HFINTOSC START-UP TIMES vs. VDD OVER TEMPERATURE

FIGURE 16-37: TYPICAL HFINTOSC FREQUENCY CHANGE vs. VDD (25°C)

-40C to +85C

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Time (μs)

-40°C

25°C

85°C

Typical: Statistical Mean @25°C

Maximum: Mean (Worst Case Temp) + 3σ

(-40°C to 125°C)

-5

-4

-3

-2

-1

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Cha n ge f r o m C a librat i on (%)

PIC16F684

FIGURE 16-38: TYPICAL HFINTOSC FREQUENCY CHANGE OVER DEVICE VDD (85°C)

FIGURE 16-39: TYPICAL HFINTOSC FREQUENCY CHANGE vs. VDD (125°C)

-5

-4

-3

-2

-1

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Change from Calibration (%)

-5

-4

-3

-2

-1

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Change from Calibr a tion (%)

PIC16F684

FIGURE 16-40: TYPICAL HFINTOSC FREQUENCY CHANGE vs. VDD (-40°C)

-5

-4

-3

-2

-1

2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5

VDD (V)

Change from Calibr a tion (%)

PIC16F684

NOTES:

PIC16F684

17.0 PACKAGING INFORMATION

17.1 Package Marking Information

*Standard PIC device marking consists of Microchip part number, year code, week code, and traceability

code. For PIC device marking beyond this, certain price adders apply. Please check with your Microchip

Sales Office. For QTP devices, any special marking adders are included in QTP price.

XXXXXX

16-Lead QFN

XXXXXX

YWWNNN

16F684-I

Example

/ML

510017

14-Lead PDIP

XXXXXXXXXXXXXX

YYWWNNN

Example

PIC16F684

0510017

14-Lead SOIC (.150”)

XXXXXXXXXXX

YYWWNNN

Example

PIC16F684-E

0510017

14-Lead TSSOP

XXXXXXXX

YYWW

NNN

Example

XXXX/ST

0510

017

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 th e full Mi crochi p pa rt numbe r cannot be marke d on one li ne, it will

be carried over to the next line, thus limiting the number of available

characters for customer-specific information.

-I/P

PIC16F684

17.2 Package Details

The following sections give the technical details of the packages.

14-Lead Plastic Dual In-Line (P or PD) – 300 mil Body [PDIP]

Notes:

1. Pin 1 visual index feature may vary, but must be located with 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 14

Pitch e .100 BSC

Top to Seating Plane A – – .210

Molded Package Thickness A2 .115 .130 .195

Base to Seating Plane A1 .015 – –

Shoulder to Shoulder Width E .290 .310 .325

Molded Package Width E1 .240 .250 .280

Overall Length D .735 .750 .775

Tip to Seating Plane L .115 . 130 .150

Lead Thickness c .008 .010 .015

Upper Lead Width b1 .045 .060 .070

Lower Lead Width b .014 .018 .022

Overall Row Spacing § eB – – .430

NOTE 1

123

Microchip Technology Drawing C04-005

PIC16F684

14-Lead Plastic Small Outline (SL or OD) – Narrow, 3.90 mm Body [SOIC]

otes:

. Pin 1 visual index feature may vary, but must be located within the hatched area.

. § Significant Characteristic.

. Dimens ions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.

. Dimens ioning 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 14

Pitch e 1.27 BSC

Overall Height A – – 1.75

Molded Package Thickness A2 1.25 – –

Standoff § A1 0.10 – 0.25

Overall Width E 6.00 BSC

Molded Package Width E1 3.90 BSC

Overall Length D 8.65 BSC

Chamfer (optional) h 0.25 – 0.50

Foot Length L 0.40 – 1. 27

Footprint L1 1.04 REF

Foot Angle φ0° – 8°

Lead Thickness c 0.17 – 0.25

Lead Width b 0.31 – 0. 51

Mold Draft Angle Top α5° – 15°

Mold Draft Angle Bottom β5° – 15°

NOTE 1

123

hα

Microchip Technology Drawing C04-065

PIC16F684

14-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP]

Notes:

1. Pin 1 visual index feature may vary, but must be located within the hatched area.

2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side.

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 14

Pitch e 0.65 BS C

Overall Height A – – 1.20

Molded Package Thickness A2 0.80 1.00 1.05

Standoff A1 0.05 – 0.15

Overall Width E 6.40 BSC

Molded Package Width E1 4.30 4.40 4.50

Molded Package Length D 4.90 5.00 5.10

Foot Length L 0.45 0.60 0.75

Footprint L1 1.00 REF

Foot Angle φ0° – 8°

Lead Thickness c 0.09 – 0.20

Lead Width b 0.19 – 0.30

NOTE 1

L1 L

Microchip Technology Drawing C04-087

PIC16F684

16-Lead Plastic Quad Flat, No Lead Package (ML) – 4x4x0.9 mm Body [QFN]

otes:

. Pin 1 visual index feature may vary, but must be located within the hatched area.

. Package is saw singulated.

. Dimens ioning 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 16

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 4.00 BSC

Exposed Pad Width E2 2.50 2.65 2. 80

Overall Length D 4.00 BSC

Exposed Pad Length D2 2.50 2 .65 2. 80

Contact Width b 0.25 0.30 0.35

Contact Length L 0.30 0.40 0.50

Contact-to-Exposed Pad K 0.20 – –

EXPOSED

PAD

NOTE 1

TOP VIEW BOTTOM VIEW

Microchip Technology Drawing C04-127

PIC16F684

NOTES:

© 2007 Microchip Technology Inc. DS41202F-page 179
PIC16F684
APPENDIX A: DATA SHEET 
REVISION HISTORY
Revision A
This is a new data sheet.
Revision B
Rewr ites of the  Oscillat or and Sp ecial Fe atures of  the
CPU Sections. General corrections to Figures and
formatting.
Revision C
Revision D
Added Characterization Data. Updated Electrical
Specifications. Incorporated Golden Chapter Sections
for the following:
•Section 3.0 “Oscillator Module (With Fail-Safe 
Clock Monitor)”
•Section 5.0 “Timer0 Module”
•Section 6.0 “Timer1 Module with Gate Control”
•Section 7.0 “Timer2 Module”
•Section 8.0 “Comparator Module”
•Section 9.0 “Analog-to-Digital Converter (ADC) 
Module”
•Section 1 1.0 “Enhanced Capture/Compare/PWM 
(With Auto-Shutdown and Dead Band) Module”
Revision E
Updated Package Drawings; Replace PICmicro with
PIC.
Revision F (03/2007)
Replaced Package Drawings (Rev. AM); Replaced
Development Support Section.
APPENDIX B: MIGRATING FROM 
OTHER PIC® 
DEVICES
This discusses some of the issues in migrating from
other PIC devices to the PIC16F6XX Family of devices.
B.1 PIC16F676 to PIC16F684
TABLE B-1: FEATURE COMPARISON
Feature PIC16F676 PIC16F684
Max Operating 
Speed 20 MHz 20 MHz
Max Program 
Memory (Words) 1024 2048
SRAM (bytes) 64 128
A/D Resolution 10-bit 10-bit
Data EEPROM 
(Bytes) 128 256
Timers (8/16-bit) 1/1 2/1
Oscillator Modes 8 8
Brown-out Reset Y Y
Internal Pull -up s RA0/1/2/4/5 RA0/1/ 2/4/ 5, 
MCLR
Interrupt-on-change RA0/1/2/3/4/5 RA0/1/2/3/4/5
Comparator 1 2
ECCP N Y
Ultra Low-Power 
Wake-Up NY
Extended WDT N Y
Software Control 
Option of WDT/BOR NY
INTO SC 
Frequencies 4MHz 32kHz-
8MHz
Clock Switch in g N Y
Note: This device has been designed to perform
to the parameters of its data sheet. It has
been tested to an electrical specification
designed to determine its conformance
with these parameters. Due to process
differences in the manufacture of this
device, this device may have different
performan ce c harac teristi cs than  it s ea rlier
version. These differences may cause this
device to perform differently in your
application than the earlier version of this
device.

PIC16F684

NOTES:

© 2007 Microchip Technology Inc.     DS41202F-page 181
PIC16F684
INDEX
A
A/D Specifications....................................................147, 148
Absolute Maximum Ratings..............................................129
AC Characteristics
Industrial and Extended............................................139
Load Conditions................ .. .. .. ..... .. .. .... .. .. .. .. ..... .... .. ..138
ADC ....................................................................................65
Acquisition Requirements ..... ......... .... .... .... ......... .... ....72
Associ a te d  registers................ ............................ ........74
Block Diag ram............. ........................... .....................65
Calculating Acquisition Time.......................................72
Channel Selection................................ .... .. ....... .... .. ....66
Configuration...............................................................66
Configuring Interrupt...................................................68
Conversi o n  Clo ck...... ..................... .............. ...............66
Conversion Procedure ...... .. .... ....... .... .... .. .... ......... .. ....68
Internal Sampling Switch (RSS) Impedance................72
Interrupts.....................................................................67
Operation....................................................................68
Operation During Sleep ..............................................68
Port Configuration.......................................................66
Reference Voltage (VREF)...........................................66
Result For matting............ ............... ..................... ........67
Source Impedance................................. ...... ......... .... ..72
Special Event Trigger..................................................68
Starting an A/D Conversion ........................................67
ADCON0 Register ...............................................................70
ADCON1 Register ...............................................................70
ADRESH Register (ADFM = 0)...........................................71
ADRESH Register (ADFM = 1)...........................................71
ADRESL Register (ADFM = 0)............................................71
ADRESL Register (ADFM = 1)............................................71
Analog Input Connection Considerations............................57
Analog-to-Digital Converter. See ADC
ANSEL Register..................................................................32
Assembler
MPASM Assembler...................................................126
B
Block Diagrams
(CCP) Capture Mode Operation .................................80
ADC ............................................................................65
ADC Transfer Function...............................................73
Analog Input Model...............................................57, 73
CCP PWM...................................................................82
Clock Source...............................................................19
Comparator 1.................. ........................... .................56
Comparator 2.................. ........................... .................56
Comparator Modes ... .. .. .... .. .. ....... .. .... .. .. .... .. ....... .. .. ....58
Compare.....................................................................81
Crystal Operation........................................................22
External RC Mode.......................................................23
Fail-Safe Clock Monitor (FSCM).................................29
In-Circuit Serial Programming Connections..............114
Inter rupt Logic.................................. .........................107
MCLR Circuit................... ..................... .....................100
On-Chip Rese t Circuit................ .............. ............... ....99
PIC16F684....................................................................5
PWM (Enhanced)...................................................... ..85
RA0 Pins.....................................................................35
RA1 Pins.....................................................................36
RA2 Pin .......................................................................36
RA3 Pin .......................................................................37
RA4 Pin ...................................................................... 37
RA5 Pin ...................................................................... 38
RC0 and RC1 Pins.................... .... .. .. .. ..... .. .. .. .. .. .. .. .. .. 41
RC2 and RC3 Pins.................... .... .. .. .. ..... .. .. .. .. .. .. .. .. .. 41
RC4 Pin...................................................................... 42
RC5 Pin...................................................................... 42
Resonator Operation.................................................. 22
Timer1 ........................................................................ 47
Timer2 ........................................................................ 53
TMR0/WDT Prescaler ................................................ 43
Watchdog Timer (WDT).......................................... .. 110
Brown-o u t Re set (BOR)............... .............. ..................... .. 101
Associated................................................................ 102
Calibration ................................................................ 101
Specifications ........................................................... 143
Timing and Characteristics......................... .. .... .. .... .. 142
C
C Compilers
MPLAB C18........ ........................... ..................... ...... 126
MPLAB C30........ ........................... ..................... ...... 126
Calibration Bits.................................................................... 99
Capture Module. See Enhanced Capture/
Compare/PWM (ECCP)
Capture/Compare/PWM (CCP)
Associated registers w/ Capture/Compare/PWM ..... .. 96
Capture Mod e............. ..................... ........................... 80
CCP1 Pin Configuration ................ ..................... ........ 80
Compare Mode....... ..................... ..................... .......... 81
CCP1 Pin Configuration.............. ..................... .. 81
Software Interrupt Mode............................... 80, 81
Special Event Trigger......................................... 81
Timer1 Mode Selection................................. 80, 81
Prescaler .................................................................... 80
PWM Mode............. ........................... ......................... 82
Duty Cycle............................. ..................... ........ 83
Effects of Reset..................... ..................... ........ 84
Example PWM Frequencies  and 
Resolutions, 20 MHZ.................................. 83
Example PWM Frequencies  and 
Resolutions, 8 MHz.................................... 83
Operation in Sleep Mode............................ .... .. .. 84
Setup for Operation............................................ 84
System Clock Frequency Changes. ................... 84
PWM Period .. .......................... ................................. .. 83
Setup for PWM Operation .......................................... 84
CCP1CON (Enhanced) Register.......................... .... .... .. .... 79
Clock Sources
External Modes........................................................... 21
EC ...................................................................... 21
HS ...................................................................... 22
LP....................................................................... 22
OST.................................................................... 21
RC ...................................................................... 23
XT....................................................................... 22
Internal Modes............................................................ 23
Frequency Selection........................................... 25
HFINTOSC......................................................... 23
HFIN T OSC/ L F IN TOSC  Swit ch  Ti min g.. .. ...... ..... 2 5
INTOSC.............................................................. 23
INTOSCIO.......................................................... 23
LFINTOSC.......................................................... 25
Clock Switching.................................................................. 27
CMCON0 Regis te r........ ..................... ..................... ............ 61

PIC16F684
DS41202F-page 182 © 2007 Microchip Technology Inc.
CMCON1 Register..............................................................62
Code Examples
A/D Conversion.... ............... ..................... ............... ....69
Assigni n g  Prescale r to Timer0..................... ...............44
Assigni n g  Prescale r to WDT.............................. .........44
Changing Between Capture Prescalers......................80
Data EEPROM Read...... ..................... ..................... ..77
Data EEPROM Wr ite .................. ..................... ...........77
Indirect Addressing .....................................................19
Initializing PORTA.......................................................31
Initializing PORTC.......................................................40
Saving Status and W Registers in RAM ...................109
Ultra  L o w - Pow e r Wake - U p  In i tializa ti o n.......... ......... ...3 4
Write Verify .................................................................77
Code Protection ................................................................113
Comparator.........................................................................55
C2OUT as T1 Gate....... ..................... ..................... ....62
Configurations.............................................................58
Interrupts.....................................................................59
Operation ....................................................................59
Operation During Sleep ..............................................60
Overview.....................................................................55
Response Time...........................................................59
Synchronizing COUT w/Timer1 ..................................62
Comparator Module
Associ a te d  Re g i sters ........ ........................... ...............64
Comparator Voltage Reference (CVREF)
Response Time...........................................................59
Comparator Voltage Reference (CVREF)............................63
Effects of a Reset........................................................60
Specifications............................................................146
Comparators
C2OUT as T1 Gate....... ..................... ..................... ....49
Effects of a Reset........................................................60
Specifications............................................................146
Compare Module. See Enhanced Capture/
Compare/PWM (ECCP)
CONFIG Regi ster.................... ..................... ..................... ..98
Configuration Bits................................................................97
CPU Features .....................................................................97
Customer Change Notification Service .................... .........187
Custome r Notification Ser vice.................... .............. .........187
Customer Support........................................................ .....187
D
Data EEPRO M Memor y
Associ a te d  Re g i sters ........ ........................... ...............78
Code Protection ....................................................75, 78
Data Memory.........................................................................7
DC and AC Characteristics
Graphs and Tables ...................................................151
DC Characteristics
Extended and Industrial. ...........................................135
Industrial and Extended............................................131
Development Support .......................................................125
Device Overview...................................................................5
E
ECCP. See Enhanced Captur e/Compare/ PWM
ECCPAS Register........ ..................... ..................... .............93
EEADR Register .................................................................75
EECON1 Regist e r............................. ............... ...................76
EECON2 Regist e r............................. ............... ...................76
EEDAT Regi ster.................... ..................... ..................... ....75
EEPROM Data Memory
Avoiding Spurious Write..............................................78
Reading ...................................................................... 77
Write Verify................................................................. 77
Writing ........................................................................ 77
Effects o f  Reset
PWM mode............... ........................... ....................... 84
Electrical Specifications.................................................... 129
Enhanced Capture/Compare/PWM ........... .. .... .. ......... .. .. ....79
Enhanced Capture/Compare/PWM (ECCP)
Enhanced PWM Mode................................. ........... .... 85
Auto-Restart ....................................................... 94
Auto-shutdown.................................................... 93
Direction Change in Full-Bridge Output Mode.... 91
Full-Bridge Application........................................ 89
Full-Bridge Mode ........ .... ......... .... .... .... ......... .... .. 89
Half-Bridge Application....................................... 88
Half-Bridge Application Examples ...................... 95
Half-Bridge Mode. ............................................... 88
Output Relationships (Active-High and
 Active-Low)................... ............................. 86
Output Relationships Diagram........... ............... .. 87
Programmable Dead-Band Delay....................... 95
Shoot-through Current........................................ 95
Start- u p  Considerati o n s..... .............. ................... 92
Specifications ........................................................... 145
Timer Resources........................................................ 79
Errata.................................................................................... 4
F
Fail-Safe Clock Monitor ...................................................... 29
Fail-Safe Condition Clearing....................................... 29
Fail-Safe Detection..................................................... 29
Fail-Safe Operation..................................................... 29
Reset or Wak e-u p  from Sleep ......... ..................... ...... 29
Firmware Instructions .......................................................115
Fuses. See Configuration Bits
G
General Purpose Register File ...................... .... ........... .... .... 8
I
ID Locations...................................................................... 113
In-Circuit Debugger ........................................................... 114
In-Circuit Serial Programming (ICSP)............................... 114
Indirect Addressing, INDF and FSR registers . .................... 19
Instruction Format............................................................. 115
Instruction Set................................................................... 115
ADDLW..................................................................... 117
ADDWF..................................................................... 117
ANDLW..................................................................... 117
ANDWF..................................................................... 117
BCF .......................................................................... 117
BSF........................................................................... 117
BTFSC...................................................................... 117
BTFSS...................................................................... 118
CALL......................................................................... 118
CLRF ........................................................................ 118
CLRW....................................................................... 118
CLRWDT .................................................................. 118
COMF....................................................................... 118
DECF........................................................................ 118
DECFSZ ................................................................... 119
GOTO....................................................................... 119
INCF ......................................................................... 119
INCFSZ..................................................................... 119
IORLW...................................................................... 119
IORWF...................................................................... 119

© 2007 Microchip Technology Inc.     DS41202F-page 183
PIC16F684
MOVF........................................................................120
MOVLW ....................................................................120
MOVWF....................................................................120
NOP..........................................................................120
RETFIE.....................................................................121
RETLW .....................................................................121
RETURN...................................................................121
RLF...........................................................................122
RRF...........................................................................122
SLEEP ......................................................................122
SUBLW.....................................................................122
SUBWF.....................................................................123
SWAPF.....................................................................123
XORLW.....................................................................123
XORWF.....................................................................123
Summary Ta b l e..... ..................... ........................... ....116
INTCON Register................................................................15
Internal Oscillator Block
INTOSC
Specifications............................................140, 141
Internal Sampling Switch (RSS) Impedance........................72
Inter n e t Ad d ress............ ........................... .........................187
Interrupts...........................................................................106
ADC ............................................................................68
Associ a te d  Re g i sters................... ........................... ..108
Comparator.................................................................59
Context Saving..........................................................109
Data EEPROM Mem o ry Write ..................... ...............76
Interrupt-on-Change....................................................32
PORTA Interrupt-on-C hange ....................................107
RA2/INT....................................................................106
Timer0.......................................................................107
TMR1..........................................................................49
INTOSC Specifications ........... .... ........... .... ...... .... .....140, 141
IOCA Register............................. ............................ ............33
L
Load Conditions............................ .. ....... .. .. .. .. .. .. ....... .. .. .. ..138
M
MCLR................................................................................100
Internal......................................................................100
Memory Organization............................................................7
Data ..............................................................................7
Data EEPROM Mem o ry...... ..................... ...................75
Program........................................................................7
Microc h i p  In ternet Web Site............................... ...............187
Migra tin g from other PICmicro Devices ...................... ......179
MPLAB ASM30 Assembler, Linker, Librarian ...................126
MPLAB ICD 2 In-Circuit Debugger ...................................127
MPLAB ICE 2000 High-Perform ance Universal 
In-Circuit Emulator....................................................127
MPLAB Integrated Development Environment Software..125
MPLAB PM3 Device Programmer ....................................127
MPLAB REA L  IC E In -Circuit Em u l a to r System.................127
MPLINK Object Linker/MPLIB Object Libraria n................126
O
OPCODE Fiel d  Descri p tions........... ............... ...................115
OPTION Register..........................................................14, 45
OSCCON Register..............................................................20
Oscillator
Associ a te d  registers................ ............................ ..30, 51
Oscillator Module ................................................................19
EC...............................................................................19
HFINTOSC..................................................................19
HS............................................................................... 19
INTOSC...................................................................... 19
INTOSCIO.................................................................. 19
LFINTOSC.................................................................. 19
LP............................................................................... 19
RC .............................................................................. 19
RCIO........................................................................... 19
XT............................................................................... 19
Oscillato r Parameters....... ................................ ................ 140
Oscillato r S pecifications.... ............... ........ ......................... 139
Oscillator Start-up Timer (OST)
Specifications ........................................................... 143
Oscillator Switching
Fail-Safe Clock Monitor.............................................. 29
Two-Spe ed Clock Start-up ....................... .................. 27
OSCTUNE Regis te r.............. ..................... ..................... .... 24
P
P1A/P1B/P1C/P1D.See Enhanced Capture/
Compare/PWM (ECCP).............................................. 85
Packaging......................................................................... 173
Marking..................................................................... 173
PDIP Details............................................................. 174
PCL and PCLATH............................................................... 19
Stack........................................................................... 19
PCON Register........................................................... 18, 102
PICSTART Plus Development Programmer..................... 128
PIE1 Register ..................................................................... 16
Pin Diagram
PDIP, SOIC, TSSOP.... ............................ .................... 2
QFN.............................................................................. 3
Pinout Descriptions
PIC16F684 ................................................................... 6
PIR1 Register ..................................................................... 17
PORTA ............................................................................... 31
Additional Pin Functions............................................. 32
ANSEL Register................................................. 32
Interrupt-on-Change........................................... 32
Ultra Low-Power Wake-Up........................... 32, 34
Weak Pull-up...................................................... 32
Associ a te d  registers................ ..................... .............. 39
Pin Descriptions and Diagrams .................................. 35
RA0............................................................................. 35
RA1............................................................................. 35
RA2............................................................................. 36
RA3............................................................................. 37
RA4............................................................................. 37
RA5............................................................................. 38
Specifications ........................................................... 141
PORTA Register................................................................. 31
PORTC............................................................................... 40
Associ a te d  registers.......... ........................... .............. 42
P1A/P1B/P1C/P1D.See Enhanced Capture/
Compare/PWM (ECCP)...................................... 40
Specifications ........................................................... 141
PORTC Register................................................................. 40
Power-Down Mode (Sleep)............................................... 112
Power-on Reset (POR)..................................................... 100
Power-up Timer (PWRT).................................................. 100
Specifications ........................................................... 143
Precisio n In ternal Osci lla to r  Pa rameters...................... .... 141
Prescaler
Shared WDT/Timer0....... ..................... ..................... .. 44
Switching Prescaler Assignment................................ 44
Program Memory.................................................................. 7
Map and Stack .............................................................. 7

PIC16F684
DS41202F-page 184 © 2007 Microchip Technology Inc.
Programming, Device Instructions....................................115
PWM Mode. See Enhan ced C apture/Compare/ PW M ........85
PWM1CON Regist er........ ............... ..................... ...............96
R
Reader Response.............................................................188
Read-Modify-Write Operations. .........................................115
Registers
ADCON0 (ADC Control 0) ..........................................70
ADCON1 (ADC Control 1) ..........................................70
ADRESH (ADC Result High) with  ADFM  = 0).............71
ADRESH (ADC Result High) with  ADFM  = 1).............71
ADRESL (ADC Result Low) with ADFM = 0)..............71
ADRESL (ADC Result Low) with ADFM = 1)..............71
ANSEL (Analog Select) ...............................................32
CCP1CON (Enhanced CCP1 Control)........................79
CMCON0 (Comparator Control 0) ..............................61
CMCON1 (Comparator Control 1) ..............................62
CONFIG (Conf ig u ration Word)....................... .............98
Data Memor y Map ............ ..................... ..................... ..8
ECCPAS (Enhanced CCP Auto-shutdown Control) ...93
EEADR (EEPROM Address) ......................................75
EECON1 (EEPROM Control 1 )...................... .............76
EECON2 (EEPROM Control 2 )...................... .............76
EEDAT (EEPROM Data) ................... ..................... ....75
INTCON (Interrupt Control).........................................15
IOCA (Interrupt-on-Change PORTA)..........................33
OPTION_R EG (OPTION).....................................14, 45
OSCCON (Oscillator Control) .....................................20
OSCTUNE (Oscillator Tuning )........ ............... .............24
PCON (Power Control Register).................................18
PCON (Power Control) .............................................102
PIE1 (Peripheral Interrupt Enable 1)...........................16
PIR1 (Peripheral Interrupt Register 1) ........................17
PORTA........................................................................31
PORTC .......................................................................40
PWM1CON (Enhanced PWM Control) .......................96
Reset Value s................... ..................... .....................104
Reset Values (Special Registers) .............................105
Special Function Registers...........................................8
Special Register Summary .........................................11
STATUS......................................................................13
T1CON........................................................................50
T2CON........................................................................54
TRISA (Tri-State PORTA)...........................................31
TRISC (Tri -State PORTC) ...... ............... .....................40
VRCON (Voltage Reference Control) .........................63
WDTCON (Watchdog Tim er Contro l)........................111
WPUA (Wea k Pull-Up PORTA) .... ..............................33
Reset...................................................................................99
Revision History................................................................179
S
Shoot-through Current ........................................................95
Sleep
Power-Down Mode ...................................................112
Wake-up....................................................................112
Wake-up Using Interrupts.........................................112
Softwa re Simulator (MP L AB SIM)................................ .....126
Special Event Trigger..........................................................68
Special Function Registers ...................................................8
STATUS Regi ster....... ..................... ..................... ...............13
T
T1CON Regis te r... .............. ..................... ..................... .......50
T2CON Regis te r... .............. ..................... ..................... .......54
Thermal Considerations.................................................... 137
Time-out Sequence ...................... .. ......... .. .... .... .. ......... .... 102
Timer0................................................................................. 43
Associ a te d  Re g i sters................... ........................... .... 45
External Clock............................................................. 44
Interrupt ...................................................................... 45
Operation.............................................................. 43, 47
Specifications ........................................................... 144
T0CKI ......................................................................... 44
Timer1................................................................................. 47
Associ a te d  registers............. ............................ .......... 51
Asynchronous Counter Mode..................................... 48
Reading and Writing........................................... 48
Interrupt ...................................................................... 49
Modes of Ope ration........ ..................... ..................... .. 47
Operation During Sleep.............................................. 49
Oscillator..................................................................... 48
Prescaler .................................................................... 48
Specifications ........................................................... 144
Timer1 Gate
Inverting Gate..................................................... 49
Selectin g  So u rce ........................... ............... 49, 62
Synchronizing COUT w/Timer1.......................... 62
TMR1H Register......................................................... 47
TMR1L Register.......................................................... 47
Timer2
Associ a te d  registers.................... ..................... .......... 54
Timers
Timer1
T1CON ............................................................... 50
Timer2
T2CON ............................................................... 54
Timing Diagrams
A/D Conver sion....... ..................... ..................... ........149
A/D Conversion (Sleep Mode).................................. 149
Brown-o ut Re set (BOR)............... ..................... ........ 142
Brown-o u t Re set Situations....... ..................... .......... 101
CLKOUT and I/O ...................................................... 141
Clock Timing............................................................. 139
Comparator Output...................... ..................... .......... 55
Enhanced Capture/Compare/PWM (ECCP)............. 145
Fail-Safe Clock Monitor (FSCM)................................. 30
Full-Bridge PWM Output............................................. 90
Half-Bridge PWM Output...................................... 88, 95
INT Pin Interrupt ....................................................... 108
Inte rn a l  Oscillato r  Sw i t c h  Ti ming ...... ...... ......... ...... ..... 26
PWM Auto-shutdown
Auto-restart Enabled........................................... 94
Firmware Restart................................................ 94
PWM Direction Change................... .... .. .... .. ......... .... .. 91
PWM Direction Change at Near 100% Duty Cycle..... 92
PWM Output  (Active-High)............................. ............ 86
PWM Output  (A ctive-Low)............. ..................... ........ 87
Reset, WDT, OST and Power-up Timer................... 142
Time-out Sequence
Case 1.............................................................. 103
Case 2.............................................................. 103
Case 3.............................................................. 103
Timer0 and Timer1 External Clock........................... 144
Two Speed Start-up................ ....... .. .. .. .. .. .... ..... .. .. .. .... 28
Wake-up from Interrupt ............................................. 113
Timing Pa rameter Symb o l o g y .. ........................... ............. 138
TRISA Register................................................................... 31
TRISC Regist e r.... ..................... ..................... ..................... 40
Two-Spe ed Clock Start-up  Mod e....... .............. ................... 27

© 2007 Microchip Technology Inc.     DS41202F-page 185
PIC16F684
U
Ultra Low-Power Wake-Up .......................................6, 32, 34
V
Voltage Reference. See Comparator Voltage Reference
(CVREF)
Voltage References
Associ a te d  Re g i sters................... ........................... ....64
VREF. SEE ADC Reference Voltage
W
Wake-up Using Interrupts.................................................112
Watchdog Timer (WDT)................ ......... .. .... .... .... ......... .. ..110
Associ a te d  Re g i sters................... ........................... ..111
Clock Source.............................................................110
Modes.......................................................................110
Period........................................................................110
Specifications............................................................143
WDTCON Registe r ....... .............. ..................... .................111
WPUA Regist e r.... ..................... ........................... ...............33
WWW Address..................................................................187
WWW, On-Line Support .......................................................4

PIC16F684

NOTES:

PIC16F684

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PIC16F684

READER RESPONSE

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DS41202FPIC16F684

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PIC16F684

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: PIC16F684, PIC16F684T(1)

VDD range 2.0V to 5.5V

Temperature

Range: I= -40°C to +85°C (Industrial)

E= -40°C to +125°C (Extended)

Package: ML = Quad Flat No Leads (QFN)

P = Plastic DIP

SL = 14-lead Small Outline (3.90 mm)

ST = Thin Shr i nk Small Outline (4.4 mm)

Pattern: QTP, SQTPSM or ROM Code; Special Requirements

(blank oth erwi se )

Examples:

a) PIC16F684-E/P 301 = Extended Temp., PDIP

package, 20 MHz, QTP patter n #301

b) PIC16F684-I/SO = Industrial Temp., SOIC

package, 20 MHz

Note 1: T = in tape and reel TSSOP, SOIC and

QFN packages only.

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12/08/06