PIC18F2420/2520/4420/4520 Data Sheet 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology (c) 2008 Microchip Technology Inc. DS39631E 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 integrity 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 violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, Accuron, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, rfPIC, SmartShunt and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL, SmartSensor and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, In-Circuit Serial Programming, ICSP, ICEPIC, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, PICkit, PICDEM, PICDEM.net, PICtail, PIC32 logo, PowerCal, PowerInfo, PowerMate, PowerTool, REAL ICE, rfLAB, Select Mode, Total Endurance, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2008, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) 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. DS39631E-page ii (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 28/40/44-Pin Enhanced Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology Power Management Features: Peripheral Highlights (Continued): * * * * * * * * * * * Master Synchronous Serial Port (MSSP) module Supporting 3-Wire SPI (all 4 modes) and I2CTM Master and Slave modes * Enhanced Addressable USART module: - Supports RS-485, RS-232 and LIN/J2602 - RS-232 operation using internal oscillator block (no external crystal required) - Auto-wake-up on Start bit - Auto-Baud Detect * 10-Bit, up to 13-Channel Analog-to-Digital (A/D) Converter module: - Auto-acquisition capability - Conversion available during Sleep * Dual Analog Comparators with Input Multiplexing * Programmable 16-Level High/Low-Voltage Detection (HLVD) module: - Supports interrupt on High/Low-Voltage Detection Run: CPU on, Peripherals on Idle: CPU off, Peripherals on Sleep: CPU off, Peripherals off Ultra Low 50nA Input Leakage Run mode Currents Down to 11 A Typical Idle mode Currents Down to 2.5 A Typical Sleep mode Current Down to 100 nA Typical Timer1 Oscillator: 900 nA, 32 kHz, 2V Watchdog Timer: 1.4 A, 2V Typical Two-Speed Oscillator Start-up Flexible Oscillator Structure: * Four Crystal modes, up to 40 MHz * 4x Phase Lock Loop (PLL) - Available for Crystal and Internal Oscillators * Two External RC modes, up to 4 MHz * Two External Clock modes, up to 40 MHz * Internal Oscillator Block: - Fast wake from Sleep and Idle, 1 s typical - 8 use-selectable frequencies, from 31 kHz to 8 MHz - Provides a complete range of clock speeds from 31 kHz to 32 MHz when used with PLL - User-tunable to compensate for frequency drift * Secondary Oscillator using Timer1 @ 32 kHz * Fail-Safe Clock Monitor: - Allows for safe shutdown if peripheral clock stops Special Microcontroller Features: * C Compiler Optimized Architecture: - Optional extended instruction set designed to optimize re-entrant code * 100,000 Erase/Write Cycle Enhanced Flash Program Memory Typical * 1,000,000 Erase/Write Cycle Data EEPROM Memory Typical * Flash/Data EEPROM Retention: 100 Years Typical * Self-Programmable under Software Control * Priority Levels for Interrupts * 8 x 8 Single-Cycle Hardware Multiplier * Extended Watchdog Timer (WDT): - Programmable period from 4 ms to 131s * Single-Supply 5V In-Circuit Serial ProgrammingTM (ICSPTM) via Two Pins * In-Circuit Debug (ICD) via Two Pins * Wide Operating Voltage Range: 2.0V to 5.5V * Programmable Brown-out Reset (BOR) with Software Enable Option Peripheral Highlights: * * * * High-Current Sink/Source 25 mA/25 mA Three Programmable External Interrupts Four Input Change Interrupts Up to 2 Capture/Compare/PWM (CCP) modules, one with Auto-Shutdown (28-pin devices) * Enhanced Capture/Compare/PWM (ECCP) module (40/44-pin devices only): - One, two or four PWM outputs - Selectable polarity - Programmable dead time - Auto-shutdown and auto-restart Program Memory Device Data Memory Flash # Single-Word SRAM EEPROM (bytes) Instructions (bytes) (bytes) I/O 10-Bit A/D (ch) CCP/ ECCP (PWM) MSSP SPI Master I2CTM EUSART - Comp. Timers 8/16-Bit PIC18F2420 16K 8192 768 256 25 10 2/0 Y Y 1 2 1/3 PIC18F2520 32K 16384 1536 256 25 10 2/0 Y Y 1 2 1/3 PIC18F4420 16K 8192 768 256 36 13 1/1 Y Y 1 2 1/3 PIC18F4520 32K 16384 1536 256 36 13 1/1 Y Y 1 2 1/3 (c) 2008 Microchip Technology Inc. DS39631E-page 1 PIC18F2420/2520/4420/4520 Pin Diagrams 28-Pin SPDIP, SOIC PIC18F2420 PIC18F2520 1 2 3 4 5 6 7 8 9 10 11 12 13 14 RA1/AN1 RA0/AN0 28-Pin QFN 28 27 26 25 24 23 22 21 20 19 18 17 16 15 RB7/KBI3/PGD RB6//KBI2/PGC RB5/KBI1/PGM RB4/KBI0/AN11 RB3/AN9/CCP2(1) RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RC7/RX/DT RC6/TX/CK RC5/SDO RC4/SDI/SDA MCLR/VPP/RE3 RB7/KBI3/PGD RB6/KBI2/PGC RB5/KBI1/PGM RB4KBI0/AN11 MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1 RC3/SCK/SCL 28 27 26 25 24 23 22 1 2 3 4 5 6 7 PIC18F2420 PIC18F2520 8 9 10 11 12 13 14 21 20 19 18 17 16 15 RB3/AN9/CCP2(1) RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RC7/RX/DT 40-Pin PDIP MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT RE0/RD/AN5 RE1/WR/AN6 RE2/CS/AN7 VDD VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1/P1A RC3/SCK/SCL RD0/PSP0 RD1/PSP1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 PIC18F4420 PIC18F4520 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1 RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT VSS OSC1/CLKI/RA7 OSC2/CLKO/RA6 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 RB7/KBI3/PGD RB6/KBI2/PGC RB5/KBI1/PGM RB4/KBI0/AN11 RB3/AN9/CCP2(1) RB2/INT2/AN8 RB1/INT1/AN10 RB0/INT0/FLT0/AN12 VDD VSS RD7/PSP7/P1D RD6/PSP6/P1C RD5/PSP5/P1B RD4/PSP4 RC7/RX/DT RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2 Note 1: RB3 is the alternate pin for CCP2 multiplexing. DS39631E-page 2 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2 RD1/PSP1 RD0/PSP0 RC3/SCK/SCL RC2/CCP1/P1A RC1/T1OSI/CCP2(1) NC Pin Diagrams (Cont.'d) 44 43 42 41 40 39 38 37 36 35 34 44-pin TQFP 33 32 31 30 29 28 27 26 25 24 23 PIC18F4420 PIC18F4520 12 13 14 15 16 17 18 19 20 21 22 1 2 3 4 5 6 7 8 9 10 11 NC RC0/T1OSO/T13CKI OSC2/CLKO/RA6 OSC1/CLKI/RA7 VSS VDD RE2/CS/AN7 RE1/WR/AN6 RE0/RD/AN5 RA5/AN4/SS/HLVDIN/C2OUT RA4/T0CKI/C1OUT 44 43 42 41 40 39 38 37 36 35 34 1 2 3 4 5 6 7 8 9 10 11 PIC18F4420 PIC18F4520 33 32 31 30 29 28 27 26 25 24 23 OSC2/CLKO/RA6 OSC1/CLKI/RA7 VSS VSS VDD VDD RE2/CS/AN7 RE1/WR/AN6 RE0/RD/AN5 RA5/AN4/SS/HLVDIN/C2OUT RA4/T0CKI/C1OUT RB3/AN9/CCP2(1) NC RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RC7/RX/DT RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D VSS VDD VDD RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 12 13 14 15 16 17 18 19 20 21 22 44-pin QFN RC6/TX/CK RC5/SDO RC4/SDI/SDA RD3/PSP3 RD2/PSP2 RD1/PSP1 RD0/PSP0 RC3/SCK/SCL RC2/CCP1/P1A RC1/T1OSI/CCP2(1) RC0/T1OSO/T13CKI NC NC RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD MCLR/VPP/RE3 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RC7/RX/DT RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D VSS VDD RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1) Note 1: RB3 is the alternate pin for CCP2 multiplexing. (c) 2008 Microchip Technology Inc. DS39631E-page 3 PIC18F2420/2520/4420/4520 Table of Contents 1.0 Device Overview .......................................................................................................................................................................... 7 2.0 Oscillator Configurations ............................................................................................................................................................ 23 3.0 Power-Managed Modes ............................................................................................................................................................. 33 4.0 Reset .......................................................................................................................................................................................... 41 5.0 Memory Organization ................................................................................................................................................................. 53 6.0 Flash Program Memory .............................................................................................................................................................. 73 7.0 Data EEPROM Memory ............................................................................................................................................................. 83 8.0 8 x 8 Hardware Multiplier............................................................................................................................................................ 89 9.0 Interrupts .................................................................................................................................................................................... 91 10.0 I/O Ports ................................................................................................................................................................................... 105 11.0 Timer0 Module ......................................................................................................................................................................... 123 12.0 Timer1 Module ......................................................................................................................................................................... 127 13.0 Timer2 Module ......................................................................................................................................................................... 133 14.0 Timer3 Module ......................................................................................................................................................................... 135 15.0 Capture/Compare/PWM (CCP) Modules ................................................................................................................................. 139 16.0 Enhanced Capture/Compare/PWM (ECCP) Module................................................................................................................ 147 17.0 Master Synchronous Serial Port (MSSP) Module .................................................................................................................... 161 18.0 Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) ............................................................... 201 19.0 10-Bit Analog-to-Digital Converter (A/D) Module ..................................................................................................................... 223 20.0 Comparator Module.................................................................................................................................................................. 233 21.0 Comparator Voltage Reference Module ................................................................................................................................... 239 22.0 High/Low-Voltage Detect (HLVD)............................................................................................................................................. 243 23.0 Special Features of the CPU .................................................................................................................................................... 249 24.0 Instruction Set Summary .......................................................................................................................................................... 267 25.0 Development Support............................................................................................................................................................... 317 26.0 Electrical Characteristics .......................................................................................................................................................... 321 27.0 DC and AC Characteristics Graphs and Tables ....................................................................................................................... 361 28.0 Packaging Information.............................................................................................................................................................. 383 Appendix A: Revision History............................................................................................................................................................. 395 Appendix B: Device Differences......................................................................................................................................................... 395 Appendix C: Migration from Mid-Range to Enhanced Devices .......................................................................................................... 396 Appendix D: Migration from High-End to Enhanced Devices............................................................................................................. 396 Index .................................................................................................................................................................................................. 397 The Microchip Web Site ..................................................................................................................................................................... 407 Customer Change Notification Service .............................................................................................................................................. 407 Customer Support .............................................................................................................................................................................. 407 Reader Response .............................................................................................................................................................................. 408 PIC18F2420/2520/4420/4520 Product Identification System ............................................................................................................ 409 DS39631E-page 4 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TO OUR VALUED CUSTOMERS It is our intention to provide our valued customers with the best documentation possible to ensure successful use of your Microchip products. To this end, we will continue to improve our publications to better suit your needs. Our publications will be refined and enhanced as new volumes and updates are introduced. If you have any questions or comments regarding this publication, please contact the Marketing Communications Department via E-mail at docerrors@microchip.com or fax the Reader Response Form in the back of this data sheet to (480) 792-4150. We welcome your feedback. Most Current Data Sheet To obtain the most up-to-date version of this data sheet, please register at our Worldwide Web site at: http://www.microchip.com You can determine the version of a data sheet by examining its literature number found on the bottom outside corner of any page. The last character of the literature number is the version number, (e.g., DS30000A is version A of document DS30000). Errata An errata sheet, describing minor operational differences from the data sheet and recommended workarounds, may exist for current devices. As device/documentation issues become known to us, we will publish an errata sheet. The errata will specify the revision of silicon and revision of document to which it applies. To determine if an errata sheet exists for a particular device, please check with one of the following: * Microchip's Worldwide Web site; http://www.microchip.com * Your local Microchip sales office (see last page) When contacting a sales office, please specify which device, revision of silicon and data sheet (include literature number) you are using. Customer Notification System Register on our web site at www.microchip.com to receive the most current information on all of our products. (c) 2008 Microchip Technology Inc. DS39631E-page 5 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 6 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 1.0 DEVICE OVERVIEW This document contains device-specific information for the following devices: * PIC18F2420 * PIC18LF2420 * PIC18F2520 * PIC18LF2520 * PIC18F4420 * PIC18LF4420 * PIC18F4520 * PIC18LF4520 This family offers the advantages of all PIC18 microcontrollers - namely, high computational performance at an economical price - with the addition of high-endurance, Enhanced Flash program memory. On top of these features, the PIC18F2420/2520/4420/ 4520 family introduces design enhancements that make these microcontrollers a logical choice for many high-performance, power sensitive applications. 1.1 1.1.1 New Core Features nanoWatt TECHNOLOGY All of the devices in the PIC18F2420/2520/4420/4520 family incorporate a range of features that can significantly reduce power consumption during operation. Key items include: * Alternate Run Modes: By clocking the controller from the Timer1 source or the internal oscillator block, power consumption during code execution can be reduced by as much as 90%. * Multiple Idle Modes: The controller can also run with its CPU core disabled but the peripherals still active. In these states, power consumption can be reduced even further, to as little as 4% of normal operation requirements. * On-the-Fly Mode Switching: The powermanaged modes are invoked by user code during operation, allowing the user to incorporate power-saving ideas into their application's software design. * Low Consumption in Key Modules: The power requirements for both Timer1 and the Watchdog Timer are minimized. See Section 26.0 "Electrical Characteristics" for values. (c) 2008 Microchip Technology Inc. 1.1.2 MULTIPLE OSCILLATOR OPTIONS AND FEATURES All of the devices in the PIC18F2420/2520/4420/4520 family offer ten different oscillator options, allowing users a wide range of choices in developing application hardware. These include: * Four Crystal modes, using crystals or ceramic resonators * Two External Clock modes, offering the option of using two pins (oscillator input and a divide-by-4 clock output) or one pin (oscillator input, with the second pin reassigned as general I/O) * Two External RC Oscillator modes with the same pin options as the External Clock modes * An internal oscillator block which provides an 8 MHz clock and an INTRC source (approximately 31 kHz), as well as a range of 6 user-selectable clock frequencies, between 125 kHz to 4 MHz, for a total of 8 clock frequencies. This option frees the two oscillator pins for use as additional general purpose I/O. * A Phase Lock Loop (PLL) frequency multiplier, available to both the High-Speed Crystal and Internal Oscillator modes, which allows clock speeds of up to 40 MHz. Used with the internal oscillator, the PLL gives users a complete selection of clock speeds, from 31 kHz to 32 MHz - all without using an external crystal or clock circuit. Besides its availability as a clock source, the internal oscillator block provides a stable reference source that gives the family additional features for robust operation: * Fail-Safe Clock Monitor: This option constantly monitors the main clock source against a reference signal provided by the internal oscillator. If a clock failure occurs, the controller is switched to the internal oscillator block, allowing for continued low-speed operation or a safe application shutdown. * Two-Speed Start-up: This option allows the internal oscillator to serve as the clock source from Power-on Reset, or wake-up from Sleep mode, until the primary clock source is available. DS39631E-page 7 PIC18F2420/2520/4420/4520 1.2 Other Special Features * Memory Endurance: The Enhanced Flash cells for both program memory and data EEPROM are rated to last for many thousands of erase/write cycles - up to 100,000 for program memory and 1,000,000 for EEPROM. Data retention without refresh is conservatively estimated to be greater than 40 years. * Self-Programmability: These devices can write to their own program memory spaces under internal software control. By using a bootloader routine located in the protected Boot Block at the top of program memory, it becomes possible to create an application that can update itself in the field. * Extended Instruction Set: The PIC18F2420/ 2520/4420/4520 family introduces an optional extension to the PIC18 instruction set, which adds 8 new instructions and an Indexed Addressing mode. This extension, enabled as a device configuration option, has been specifically designed to optimize re-entrant application code originally developed in high-level languages, such as C. * Enhanced CCP Module: In PWM mode, this module provides 1, 2 or 4 modulated outputs for controlling half-bridge and full-bridge drivers. Other features include auto-shutdown, for disabling PWM outputs on interrupt, or other select conditions, and auto-restart to reactivate outputs once the condition has cleared. * Enhanced Addressable USART: This serial communication module is capable of standard RS-232 operation and provides support for the LIN bus protocol. Other enhancements include automatic baud rate detection and a 16-bit Baud Rate Generator for improved resolution. When the microcontroller is using the internal oscillator block, the EUSART provides stable operation for applications that talk to the outside world without using an external crystal (or its accompanying power requirement). * 10-Bit A/D Converter: This module incorporates programmable acquisition time, allowing for a channel to be selected and a conversion to be initiated without waiting for a sampling period and thus, reducing code overhead. * Extended Watchdog Timer (WDT): This enhanced version incorporates a 16-bit prescaler, allowing an extended time-out range that is stable across operating voltage and temperature. See Section 26.0 "Electrical Characteristics" for time-out periods. DS39631E-page 8 1.3 Details on Individual Family Members Devices in the PIC18F2420/2520/4420/4520 family are available in 28-pin and 40/44-pin packages. Block diagrams for the two groups are shown in Figure 1-1 and Figure 1-2. The devices are differentiated from each other in five ways: 1. 2. 3. 4. 5. Flash program memory (16 Kbytes for PIC18F2420/4420 devices and 32 Kbytes for PIC18F2520/4520 devices). A/D channels (10 for 28-pin devices, 13 for 40/44-pin devices). I/O ports (3 bidirectional ports on 28-pin devices, 5 bidirectional ports on 40/44-pin devices). CCP and Enhanced CCP implementation (28-pin devices have 2 standard CCP modules, 40/44-pin devices have one standard CCP module and one ECCP module). Parallel Slave Port (present only on 40/44-pin devices). All other features for devices in this family are identical. These are summarized in Table 1-1. The pinouts for all devices are listed in Table 1-2 and Table 1-3. Like all Microchip PIC18 devices, members of the PIC18F2420/2520/4420/4520 family are available as both standard and low-voltage devices. Standard devices with Enhanced Flash memory, designated with an "F" in the part number (such as PIC18F2420), accommodate an operating VDD range of 4.2V to 5.5V. Low-voltage parts, designated by "LF" (such as PIC18LF2420), function over an extended VDD range of 2.0V to 5.5V. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-1: DEVICE FEATURES Features Operating Frequency PIC18F2420 PIC18F2520 PIC18F4420 PIC18F4520 DC - 40 MHz DC - 40 MHz DC - 40 MHz DC - 40 MHz Program Memory (Bytes) 16384 32768 16384 32768 Program Memory (Instructions) 8192 16384 8192 16384 Data Memory (Bytes) 768 1536 768 1536 Data EEPROM Memory (Bytes) 256 256 256 256 Interrupt Sources 19 19 20 20 Ports A, B, C, (E) Ports A, B, C, (E) Ports A, B, C, D, E Ports A, B, C, D, E I/O Ports Timers 4 4 4 4 Capture/Compare/PWM Modules 2 2 1 1 Enhanced Capture/Compare/PWM Modules 0 0 1 1 MSSP, Enhanced USART MSSP, Enhanced USART MSSP, Enhanced USART MSSP, Enhanced USART Serial Communications Parallel Communications (PSP) No No Yes Yes 10-Bit Analog-to-Digital Module 10 Input Channels 10 Input Channels 13 Input Channels 13 Input Channels Resets (and Delays) Programmable High/Low-Voltage Detect Programmable Brown-out Reset Instruction Set Packages (c) 2008 Microchip Technology Inc. POR, BOR, POR, BOR, POR, BOR, POR, BOR, RESET Instruction, RESET Instruction, RESET Instruction, RESET Instruction, Stack Full, Stack Stack Full, Stack Stack Full, Stack Stack Full, Stack Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST), Underflow (PWRT, OST), MCLR (optional), WDT MCLR (optional), WDT MCLR (optional), WDT MCLR (optional), WDT Yes Yes Yes Yes Yes Yes Yes Yes 75 Instructions; 83 with Extended Instruction Set Enabled 75 Instructions; 83 with Extended Instruction Set Enabled 75 Instructions; 83 with Extended Instruction Set Enabled 75 Instructions; 83 with Extended Instruction Set Enabled 28-Pin SPDIP 28-Pin SOIC 28-Pin QFN 28-Pin SPDIP 28-Pin SOIC 28-Pin QFN 40-Pin PDIP 44-Pin QFN 44-Pin TQFP 40-Pin PDIP 44-Pin QFN 44-Pin TQFP DS39631E-page 9 PIC18F2420/2520/4420/4520 FIGURE 1-1: PIC18F2420/2520 (28-PIN) BLOCK DIAGRAM Data Bus<8> Table Pointer<21> Data Latch 8 8 inc/dec logic PCLATU PCLATH 21 20 Address Latch PCU PCH PCL Program Counter 31-Level Stack 12 Data Address<12> 4 BSR Address Latch Program Memory (16/32 Kbytes) PORTA Data Memory ( 3.9 Kbytes ) STKPTR 4 Access Bank 12 FSR0 FSR1 FSR2 Data Latch 12 PORTB 8 inc/dec logic Table Latch Address Decode ROM Latch Instruction Bus <16> RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT OSC2/CLKO(3)/RA6 OSC1/CLKI(3)/RA7 RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1) RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD IR Instruction Decode and Control 8 State Machine Control Signals PRODH PRODL PORTC 3 8 x 8 Multiply 8 W BITOP 8 Internal Oscillator Block OSC1(3) OSC2 (3) T1OSI INTRC Oscillator T1OSO 8 MHz Oscillator Power-up Timer Brown-out Reset Fail-Safe Clock Monitor Single-Supply Programming In-Circuit Debugger MCLR(2) VDD, VSS ALU<8> 8 Precision Band Gap Reference PORTE MCLR/VPP/RE3(2) BOR HLVD Data EEPROM Timer0 Timer1 Timer2 Timer3 Comparator CCP1 CCP2 MSSP EUSART ADC 10-Bit Note 8 8 8 Oscillator Start-up Timer Power-on Reset Watchdog Timer 8 RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1 RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT 1: CCP2 is multiplexed with RC1 when Configuration bit, CCP2MX, is set, or RB3 when CCP2MX is not set. 2: RE3 is only available when MCLR functionality is disabled. 3: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O. Refer to Section 2.0 "Oscillator Configurations" for additional information. DS39631E-page 10 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 1-2: PIC18F4420/4520 (40/44-PIN) BLOCK DIAGRAM Data Bus<8> Table Pointer<21> Data Memory ( 3.9 Kbytes ) PCLATU PCLATH 21 20 Address Latch PCU PCH PCL Program Counter 12 Data Address<12> 31-Level Stack 4 BSR Address Latch Program Memory (16/32 Kbytes) STKPTR Data Latch 8 RA0/AN0 RA1/AN1 RA2/AN2/VREF-/CVREF RA3/AN3/VREF+ RA4/T0CKI/C1OUT RA5/AN4/SS/HLVDIN/C2OUT OSC2/CLKO(3)/RA6 OSC1/CLKI(3)/RA7 Data Latch 8 8 inc/dec logic PORTA 12 FSR0 FSR1 FSR2 PORTB RB0/INT0/FLT0/AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2(1) RB4/KBI0/AN11 RB5/KBI1/PGM RB6/KBI2/PGC RB7/KBI3/PGD 4 Access Bank 12 inc/dec logic Table Latch PORTC Address Decode ROM Latch Instruction Bus <16> RC0/T1OSO/T13CKI RC1/T1OSI/CCP2(1) RC2/CCP1/P1A RC3/SCK/SCL RC4/SDI/SDA RC5/SDO RC6/TX/CK RC7/RX/DT IR 8 State Machine Control Signals Instruction Decode and Control PRODH PRODL 3 8 x 8 Multiply 8 W BITOP 8 Internal Oscillator Block OSC1(3) OSC2 (3) T1OSI INTRC Oscillator T1OSO 8 MHz Oscillator Single-Supply Programming In-Circuit Debugger MCLR(2) VDD, VSS Power-up Timer Brown-out Reset Fail-Safe Clock Monitor ALU<8> 8 PORTE Precision Band Gap Reference BOR HLVD Data EEPROM Timer0 Timer1 Timer2 Timer3 Comparator ECCP1 CCP2 MSSP EUSART ADC 10-Bit Note RD0/PSP0 :RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C RD7/PSP7/P1D 8 8 8 Oscillator Start-up Timer Power-on Reset Watchdog Timer 8 PORTD RE0/RD/AN5 RE1/WR/AN6 RE2/CS/AN7 MCLR/VPP/RE3(2) 1: CCP2 is multiplexed with RC1 when Configuration bit, CCP2MX, is set, or RB3 when CCP2MX is not set. 2: RE3 is only available when MCLR functionality is disabled. 3: OSC1/CLKI and OSC2/CLKO are only available in select oscillator modes and when these pins are not being used as digital I/O. Refer to Section 2.0 "Oscillator Configurations" for additional information. (c) 2008 Microchip Technology Inc. DS39631E-page 11 PIC18F2420/2520/4420/4520 TABLE 1-2: PIC18F2420/2520 PINOUT I/O DESCRIPTIONS Pin Number Pin Name MCLR/VPP/RE3 MCLR Pin Buffer SPDIP, QFN Type Type SOIC 1 26 VPP RE3 OSC1/CLKI/RA7 OSC1 9 6 I ST P I ST ST O -- CLKO O -- RA6 I/O TTL RA7 OSC2/CLKO/RA6 OSC2 10 Master Clear (input) or programming voltage (input). Master Clear (Reset) input. This pin is an active-low Reset to the device. Programming voltage input. Digital input. Oscillator crystal or external clock input. Oscillator crystal input or external clock source input. ST buffer when configured in RC mode; CMOS otherwise. I CMOS External clock source input. Always associated with pin function, OSC1. (See related OSC1/CLKI, OSC2/CLKO pins.) I/O TTL General purpose I/O pin. I CLKI Description 7 Oscillator crystal or clock output. Oscillator crystal output. Connects to crystal or resonator in Crystal Oscillator mode. In RC mode, OSC2 pin outputs CLKO which has 1/4 the frequency of OSC1 and denotes the instruction cycle rate. General purpose I/O pin. Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. DS39631E-page 12 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-2: PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number Pin Buffer SPDIP, QFN Type Type SOIC Description PORTA is a bidirectional I/O port. RA0/AN0 RA0 AN0 2 RA1/AN1 RA1 AN1 3 RA2/AN2/VREF-/CVREF RA2 AN2 VREFCVREF 4 RA3/AN3/VREF+ RA3 AN3 VREF+ 5 RA4/T0CKI/C1OUT RA4 T0CKI C1OUT 6 RA5/AN4/SS/HLVDIN/ C2OUT RA5 AN4 SS HLVDIN C2OUT 7 27 I/O TTL I Analog Digital I/O. Analog input 0. I/O TTL I Analog Digital I/O. Analog input 1. I/O TTL I Analog I Analog O Analog Digital I/O. Analog input 2. A/D reference voltage (low) input. Comparator reference voltage output. I/O TTL I Analog I Analog Digital I/O. Analog input 3. A/D reference voltage (high) input. I/O I O Digital I/O. Timer0 external clock input. Comparator 1 output. 28 1 2 3 ST ST -- 4 I/O TTL I Analog I TTL I Analog O -- Digital I/O. Analog input 4. SPI slave select input. High/Low-Voltage Detect input. Comparator 2 output. RA6 See the OSC2/CLKO/RA6 pin. RA7 See the OSC1/CLKI/RA7 pin. Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 13 PIC18F2420/2520/4420/4520 TABLE 1-2: PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number Pin Buffer SPDIP, QFN Type Type SOIC Description PORTB is a bidirectional I/O port. PORTB can be software programmed for internal weak pull-ups on all inputs. RB0/INT0/FLT0/AN12 RB0 INT0 FLT0 AN12 21 RB1/INT1/AN10 RB1 INT1 AN10 22 RB2/INT2/AN8 RB2 INT2 AN8 23 RB3/AN9/CCP2 RB3 AN9 CCP2(1) 24 RB4/KBI0/AN11 RB4 KBI0 AN11 25 RB5/KBI1/PGM RB5 KBI1 PGM 26 RB6/KBI2/PGC RB6 KBI2 PGC 27 RB7/KBI3/PGD RB7 KBI3 PGD 28 18 I/O TTL I ST I ST I Analog Digital I/O. External interrupt 0. PWM Fault input for CCP1. Analog input 12. I/O TTL I ST I Analog Digital I/O. External interrupt 1. Analog input 10. I/O TTL I ST I Analog Digital I/O. External interrupt 2. Analog input 8. I/O TTL I Analog I/O ST Digital I/O. Analog input 9. Capture 2 input/Compare 2 output/PWM2 output. I/O TTL I TTL I Analog Digital I/O. Interrupt-on-change pin. Analog input 11. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. Low-Voltage ICSPTM Programming enable pin. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. In-Circuit Debugger and ICSP programming clock pin. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. In-Circuit Debugger and ICSP programming data pin. 19 20 21 22 23 24 25 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. DS39631E-page 14 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-2: PIC18F2420/2520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number Pin Buffer SPDIP, QFN Type Type SOIC Description PORTC is a bidirectional I/O port. RC0/T1OSO/T13CKI RC0 T1OSO T13CKI 11 RC1/T1OSI/CCP2 RC1 T1OSI CCP2(2) 12 RC2/CCP1 RC2 CCP1 13 RC3/SCK/SCL RC3 SCK SCL 14 RC4/SDI/SDA RC4 SDI SDA 15 RC5/SDO RC5 SDO 16 RC6/TX/CK RC6 TX CK 17 RC7/RX/DT RC7 RX DT 18 8 I/O O I ST -- ST Digital I/O. Timer1 oscillator output. Timer1/Timer3 external clock input. 9 I/O ST I Analog I/O ST Digital I/O. Timer1 oscillator input. Capture 2 input/Compare 2 output/PWM2 output. I/O I/O ST ST Digital I/O. Capture 1 input/Compare 1 output/PWM1 output. I/O I/O I/O ST ST ST Digital I/O. Synchronous serial clock input/output for SPI mode. Synchronous serial clock input/output for I2CTM mode. I/O I I/O ST ST ST Digital I/O. SPI data in. I2C data I/O. I/O O ST -- Digital I/O. SPI data out. I/O O I/O ST -- ST Digital I/O. EUSART asynchronous transmit. EUSART synchronous clock (see related RX/DT). I/O I I/O ST ST ST Digital I/O. EUSART asynchronous receive. EUSART synchronous data (see related TX/CK). 10 11 12 13 14 15 RE3 -- -- -- -- See MCLR/VPP/RE3 pin. VSS 8, 19 5, 16 P -- Ground reference for logic and I/O pins. VDD 20 17 P -- Positive supply for logic and I/O pins. Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 15 PIC18F2420/2520/4420/4520 TABLE 1-3: PIC18F4420/4520 PINOUT I/O DESCRIPTIONS Pin Name MCLR/VPP/RE3 MCLR Pin Number PDIP 1 Pin Buffer QFN TQFP Type Type 18 18 VPP RE3 OSC1/CLKI/RA7 OSC1 13 32 ST P I ST 30 I CLKI I RA7 OSC2/CLKO/RA6 OSC2 I I/O 14 33 Description Master Clear (input) or programming voltage (input). Master Clear (Reset) input. This pin is an active-low Reset to the device. Programming voltage input. Digital input. Oscillator crystal or external clock input. Oscillator crystal input or external clock source input. ST buffer when configured in RC mode; analog otherwise. CMOS External clock source input. Always associated with pin function, OSC1. (See related OSC1/CLKI, OSC2/CLKO pins.) TTL General purpose I/O pin. ST 31 O -- CLKO O -- RA6 I/O TTL Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output Oscillator crystal or clock output. Oscillator crystal output. Connects to crystal or resonator in Crystal Oscillator mode. In RC mode, OSC2 pin outputs CLKO which has 1/4 the frequency of OSC1 and denotes the instruction cycle rate. General purpose I/O pin. CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. DS39631E-page 16 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-3: PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number PDIP Pin Buffer QFN TQFP Type Type Description PORTA is a bidirectional I/O port. RA0/AN0 RA0 AN0 2 RA1/AN1 RA1 AN1 3 RA2/AN2/VREF-/CVREF RA2 AN2 VREFCVREF 4 RA3/AN3/VREF+ RA3 AN3 VREF+ 5 RA4/T0CKI/C1OUT RA4 T0CKI C1OUT 6 RA5/AN4/SS/HLVDIN/ C2OUT RA5 AN4 SS HLVDIN C2OUT 7 19 20 21 22 23 24 19 I/O I TTL Analog Digital I/O. Analog input 0. I/O I TTL Analog Digital I/O. Analog input 1. I/O I I O TTL Analog Analog Analog Digital I/O. Analog input 2. A/D reference voltage (low) input. Comparator reference voltage output. I/O I I TTL Analog Analog Digital I/O. Analog input 3. A/D reference voltage (high) input. I/O I O ST ST -- I/O I I I O TTL Analog TTL Analog -- 20 21 22 23 Digital I/O. Timer0 external clock input. Comparator 1 output. 24 RA6 RA7 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output Digital I/O. Analog input 4. SPI slave select input. High/Low-Voltage Detect input. Comparator 2 output. See the OSC2/CLKO/RA6 pin. See the OSC1/CLKI/RA7 pin. CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 17 PIC18F2420/2520/4420/4520 TABLE 1-3: PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number PDIP Pin Buffer QFN TQFP Type Type Description PORTB is a bidirectional I/O port. PORTB can be software programmed for internal weak pull-ups on all inputs. RB0/INT0/FLT0/AN12 RB0 INT0 FLT0 AN12 33 RB1/INT1/AN10 RB1 INT1 AN10 34 RB2/INT2/AN8 RB2 INT2 AN8 35 RB3/AN9/CCP2 RB3 AN9 CCP2(1) 36 RB4/KBI0/AN11 RB4 KBI0 AN11 37 RB5/KBI1/PGM RB5 KBI1 PGM 38 RB6/KBI2/PGC RB6 KBI2 PGC 39 RB7/KBI3/PGD RB7 KBI3 PGD 40 9 10 11 12 14 15 16 17 8 I/O I I I TTL ST ST Analog Digital I/O. External interrupt 0. PWM Fault input for Enhanced CCP1. Analog input 12. I/O I I TTL ST Analog Digital I/O. External interrupt 1. Analog input 10. I/O I I TTL ST Analog Digital I/O. External interrupt 2. Analog input 8. I/O I I/O TTL Analog ST Digital I/O. Analog input 9. Capture 2 input/Compare 2 output/PWM2 output. I/O I I TTL TTL Analog Digital I/O. Interrupt-on-change pin. Analog input 11. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. Low-Voltage ICSPTM Programming enable pin. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. In-Circuit Debugger and ICSP programming clock pin. I/O I I/O TTL TTL ST Digital I/O. Interrupt-on-change pin. In-Circuit Debugger and ICSP programming data pin. 9 10 11 14 15 16 17 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. DS39631E-page 18 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-3: PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Name Pin Number PDIP Pin Buffer QFN TQFP Type Type Description PORTC is a bidirectional I/O port. RC0/T1OSO/T13CKI RC0 T1OSO T13CKI 15 RC1/T1OSI/CCP2 RC1 T1OSI CCP2(2) 16 RC2/CCP1/P1A RC2 CCP1 P1A 17 RC3/SCK/SCL RC3 SCK 18 34 35 36 37 32 23 RC5/SDO RC5 SDO 24 RC6/TX/CK RC6 TX CK 25 RC7/RX/DT RC7 RX DT 26 42 43 44 1 ST -- ST I/O I I/O ST CMOS ST Digital I/O. Timer1 oscillator input. Capture 2 input/Compare 2 output/PWM2 output. I/O I/O O ST ST -- Digital I/O. Capture 1 input/Compare 1 output/PWM1 output. Enhanced CCP1 output. I/O I/O ST ST I/O ST Digital I/O. Synchronous serial clock input/output for SPI mode. Synchronous serial clock input/output for I2CTM mode. I/O I I/O ST ST ST Digital I/O. SPI data in. I2C data I/O. I/O O ST -- Digital I/O. SPI data out. I/O O I/O ST -- ST Digital I/O. EUSART asynchronous transmit. EUSART synchronous clock (see related RX/DT). I/O I I/O ST ST ST Digital I/O. EUSART asynchronous receive. EUSART synchronous data (see related TX/CK). Digital I/O. Timer1 oscillator output. Timer1/Timer3 external clock input. 35 36 37 SCL RC4/SDI/SDA RC4 SDI SDA I/O O I 42 43 44 1 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 19 PIC18F2420/2520/4420/4520 TABLE 1-3: Pin Name PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Number PDIP Pin Buffer QFN TQFP Type Type Description PORTD is a bidirectional I/O port or a Parallel Slave Port (PSP) for interfacing to a microprocessor port. These pins have TTL input buffers when PSP module is enabled. RD0/PSP0 RD0 PSP0 19 RD1/PSP1 RD1 PSP1 20 RD2/PSP2 RD2 PSP2 21 RD3/PSP3 RD3 PSP3 22 RD4/PSP4 RD4 PSP4 27 RD5/PSP5/P1B RD5 PSP5 P1B 28 RD6/PSP6/P1C RD6 PSP6 P1C 29 RD7/PSP7/P1D RD7 PSP7 P1D 30 38 39 40 41 2 3 4 5 38 I/O I/O ST TTL Digital I/O. Parallel Slave Port data. I/O I/O ST TTL Digital I/O. Parallel Slave Port data. I/O I/O ST TTL Digital I/O. Parallel Slave Port data. I/O I/O ST TTL Digital I/O. Parallel Slave Port data. I/O I/O ST TTL Digital I/O. Parallel Slave Port data. I/O I/O O ST TTL -- Digital I/O. Parallel Slave Port data. Enhanced CCP1 output. I/O I/O O ST TTL -- Digital I/O. Parallel Slave Port data. Enhanced CCP1 output. I/O I/O O ST TTL -- Digital I/O. Parallel Slave Port data. Enhanced CCP1 output. 39 40 41 2 3 4 5 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. DS39631E-page 20 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 1-3: Pin Name PIC18F4420/4520 PINOUT I/O DESCRIPTIONS (CONTINUED) Pin Number PDIP Pin Buffer QFN TQFP Type Type Description PORTE is a bidirectional I/O port. RE0/RD/AN5 RE0 RD 8 25 25 AN5 RE1/WR/AN6 RE1 WR 9 26 10 27 -- I Analog I/O I ST TTL I Analog I/O I ST TTL Digital I/O. Read control for Parallel Slave Port (see also WR and CS pins). Analog input 5. Digital I/O. Write control for Parallel Slave Port (see CS and RD pins). Analog input 6. 27 AN7 RE3 ST TTL 26 AN6 RE2/CS/AN7 RE2 CS I/O I Digital I/O. Chip Select control for Parallel Slave Port (see related RD and WR). Analog input 7. I Analog -- -- -- See MCLR/VPP/RE3 pin. 6, 29 P -- Ground reference for logic and I/O pins. 7, 8, 7, 28 28, 29 P -- Positive supply for logic and I/O pins. -- -- No Connect. -- VSS 12, 31 6, 30, 31 VDD 11, 32 NC -- 13 12, 13, 33, 34 Legend: TTL = TTL compatible input ST = Schmitt Trigger input with CMOS levels O = Output CMOS = CMOS compatible input or output I = Input P = Power Note 1: Default assignment for CCP2 when Configuration bit, CCP2MX, is set. 2: Alternate assignment for CCP2 when Configuration bit, CCP2MX, is cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 21 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 22 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 2.0 OSCILLATOR CONFIGURATIONS 2.1 Oscillator Types PIC18F2420/2520/4420/4520 devices can be operated in ten different oscillator modes. The user can program the Configuration bits, FOSC<3:0>, in Configuration Register 1H to select one of these ten modes: 1. 2. 3. 4. LP XT HS HSPLL Low-Power Crystal Crystal/Resonator High-Speed Crystal/Resonator High-Speed Crystal/Resonator with PLL Enabled 5. RC External Resistor/Capacitor with FOSC/4 Output on RA6 6. RCIO External Resistor/Capacitor with I/O on RA6 7. INTIO1 Internal Oscillator with FOSC/4 Output on RA6 and I/O on RA7 8. INTIO2 Internal Oscillator with I/O on RA6 and RA7 9. EC External Clock with FOSC/4 Output 10. ECIO External Clock with I/O on RA6 2.2 Crystal Oscillator/Ceramic Resonators In XT, LP, HS or HSPLL Oscillator modes, a crystal or ceramic resonator is connected to the OSC1 and OSC2 pins to establish oscillation. Figure 2-1 shows the pin connections. The oscillator design requires the use of a parallel cut crystal. Note: Use of a series cut crystal may give a frequency out of the crystal manufacturer's specifications. FIGURE 2-1: C1(1) OSC1 XTAL C2(1) To Internal Logic RF(3) Sleep RS(2) PIC18FXXXX OSC2 Note 1: See Table 2-1 and Table 2-2 for initial values of C1 and C2. 2: A series resistor (RS) may be required for AT strip cut crystals. 3: RF varies with the oscillator mode chosen. TABLE 2-1: CAPACITOR SELECTION FOR CERAMIC RESONATORS Typical Capacitor Values Used: Mode Freq OSC1 OSC2 XT 3.58 MHz 4.19 MHz 4 MHz 4 MHz 15 pF 15 pF 30 pF 50 pF 15 pF 15 pF 30 pF 50 pF Capacitor values are for design guidance only. Different capacitor values may be required to produce acceptable oscillator operation. The user should test the performance of the oscillator over the expected VDD and temperature range for the application. See the notes following Table 2-2 for additional information. Note: (c) 2008 Microchip Technology Inc. CRYSTAL/CERAMIC RESONATOR OPERATION (XT, LP, HS OR HSPLL CONFIGURATION) When using resonators with frequencies above 3.5 MHz, the use of HS mode, rather than XT mode, is recommended. HS mode may be used at any VDD for which the controller is rated. If HS is selected, it is possible that the gain of the oscillator will overdrive the resonator. Therefore, a series resistor should be placed between the OSC2 pin and the resonator. As a good starting point, the recommended value of RS is 330. DS39631E-page 23 PIC18F2420/2520/4420/4520 TABLE 2-2: Osc Type CAPACITOR SELECTION FOR CRYSTAL OSCILLATOR Crystal Freq Typical Capacitor Values Tested: C1 C2 LP 32 kHz 30 pF 30 pF XT 1 MHz 4 MHz 15 pF 15 pF 15 pF 15 pF HS 4 MHz 10 MHz 20 MHz 25 MHz 25 MHz 15 pF 15 pF 15 pF 0 pF 15 pF 15 pF 15 pF 15 pF 5 pF 15 pF Capacitor values are for design guidance only. These capacitors were tested with the crystals listed below for basic start-up and operation. These values are not optimized. Different capacitor values may be required to produce acceptable oscillator operation. The user should test the performance of the oscillator over the expected VDD and temperature range for the application. See the notes following this table for additional information. FIGURE 2-2: EXTERNAL CLOCK INPUT OPERATION (HS OSC CONFIGURATION) OSC1 Clock from Ext. System PIC18FXXXX Open 2.3 32 kHz 4 MHz 25 MHz 10 MHz 1 MHz 20 MHz Note 1: Higher capacitance increases the stability of the oscillator but also increases the start-up time. 2: When operating below 3V VDD, or when using certain ceramic resonators at any voltage, it may be necessary to use the HS mode or switch to a crystal oscillator. 3: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 4: Rs may be required to avoid overdriving crystals with low drive level specification. 5: Always verify oscillator performance over the VDD and temperature range that is expected for the application. (HS Mode) OSC2 External Clock Input The EC and ECIO Oscillator modes require an external clock source to be connected to the OSC1 pin. There is no oscillator start-up time required after a Power-on Reset or after an exit from Sleep mode. In the EC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic. Figure 2-3 shows the pin connections for the EC Oscillator mode. FIGURE 2-3: Crystals Used: DS39631E-page 24 An external clock source may also be connected to the OSC1 pin in the HS mode, as shown in Figure 2-2. EXTERNAL CLOCK INPUT OPERATION (EC CONFIGURATION) OSC1/CLKI Clock from Ext. System PIC18FXXXX FOSC/4 OSC2/CLKO The ECIO Oscillator mode functions like the EC mode, except that the OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 6 of PORTA (RA6). Figure 2-4 shows the pin connections for the ECIO Oscillator mode. FIGURE 2-4: EXTERNAL CLOCK INPUT OPERATION (ECIO CONFIGURATION) OSC1/CLKI Clock from Ext. System PIC18FXXXX RA6 I/O (OSC2) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 2.4 RC Oscillator 2.5 For timing insensitive applications, the "RC" and "RCIO" device options offer additional cost savings. The actual oscillator frequency is a function of several factors: * supply voltage * values of the external resistor (REXT) and capacitor (CEXT) * operating temperature Given the same device, operating voltage and temperature and component values, there will also be unit-to-unit frequency variations. These are due to factors such as: * normal manufacturing variation * difference in lead frame capacitance between package types (especially for low CEXT values) * variations within the tolerance of limits of REXT and CEXT In the RC Oscillator mode, the oscillator frequency divided by 4 is available on the OSC2 pin. This signal may be used for test purposes or to synchronize other logic. Figure 2-5 shows how the R/C combination is connected. FIGURE 2-5: PLL Frequency Multiplier A Phase Locked Loop (PLL) circuit is provided as an option for users who wish to use a lower frequency oscillator circuit or to clock the device up to its highest rated frequency from a crystal oscillator. This may be useful for customers who are concerned with EMI due to high-frequency crystals or users who require higher clock speeds from an internal oscillator. 2.5.1 HSPLL OSCILLATOR MODE The HSPLL mode makes use of the HS Oscillator mode for frequencies up to 10 MHz. A PLL then multiplies the oscillator output frequency by 4 to produce an internal clock frequency up to 40 MHz. The PLLEN bit is not available in this oscillator mode. The PLL is only available to the crystal oscillator when the FOSC<3:0> Configuration bits are programmed for HSPLL mode (= 0110). FIGURE 2-7: PLL BLOCK DIAGRAM (HS MODE) HS Oscillator Enable PLL Enable (from Configuration Register 1H) RC OSCILLATOR MODE VDD OSC2 REXT OSC1 Internal Clock HS Mode OSC1 Crystal Osc FIN FOUT Loop Filter CEXT PIC18FXXXX VSS FOSC/4 OSC2/CLKO /4 The RCIO Oscillator mode (Figure 2-6) functions like the RC mode, except that the OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 6 of PORTA (RA6). RCIO OSCILLATOR MODE VDD REXT OSC1 Internal Clock VCO MUX Recommended values: 3 k REXT 100 k CEXT > 20 pF FIGURE 2-6: Phase Comparator 2.5.2 SYSCLK PLL AND INTOSC The PLL is also available to the internal oscillator block in selected oscillator modes. In this configuration, the PLL is enabled in software and generates a clock output of up to 32 MHz. The operation of INTOSC with the PLL is described in Section 2.6.4 "PLL in INTOSC Modes". CEXT PIC18FXXXX VSS RA6 I/O (OSC2) Recommended values: 3 k REXT 100 k CEXT > 20 pF (c) 2008 Microchip Technology Inc. DS39631E-page 25 PIC18F2420/2520/4420/4520 2.6 Internal Oscillator Block The PIC18F2420/2520/4420/4520 devices include an internal oscillator block which generates two different clock signals; either can be used as the microcontroller's clock source. This may eliminate the need for external oscillator circuits on the OSC1 and/or OSC2 pins. The main output (INTOSC) is an 8 MHz clock source which can be used to directly drive the device clock. It also drives a postscaler which can provide a range of clock frequencies from 31 kHz to 4 MHz. The INTOSC output is enabled when a clock frequency from 125 kHz to 8 MHz is selected. The other clock source is the internal RC oscillator (INTRC), which provides a nominal 31 kHz output. INTRC is enabled if it is selected as the device clock source; it is also enabled automatically when any of the following are enabled: * * * * Power-up Timer Fail-Safe Clock Monitor Watchdog Timer Two-Speed Start-up These features are discussed in greater detail in Section 23.0 "Special Features of the CPU". The clock source frequency (INTOSC direct, INTRC direct or INTOSC postscaler) is selected by configuring the IRCF bits of the OSCCON register (page 30). 2.6.1 INTIO MODES Using the internal oscillator as the clock source eliminates the need for up to two external oscillator pins, which can then be used for digital I/O. Two distinct configurations are available: * In INTIO1 mode, the OSC2 pin outputs FOSC/4, while OSC1 functions as RA7 for digital input and output. * In INTIO2 mode, OSC1 functions as RA7 and OSC2 functions as RA6, both for digital input and output. 2.6.2 INTOSC OUTPUT FREQUENCY The internal oscillator block is calibrated at the factory to produce an INTOSC output frequency of 8.0 MHz. The INTRC oscillator operates independently of the INTOSC source. Any changes in INTOSC across voltage and temperature are not necessarily reflected by changes in INTRC and vice versa. 2.6.3 OSCTUNE REGISTER The internal oscillator's output has been calibrated at the factory but can be adjusted in the user's application. This is done by writing to the OSCTUNE register (Register 2-1). DS39631E-page 26 When the OSCTUNE register is modified, the INTOSC frequency will begin shifting to the new frequency. The INTRC clock will reach the new frequency within 8 clock cycles (approximately 8 * 32 s = 256 s). The INTOSC clock will stabilize within 1 ms. Code execution continues during this shift. There is no indication that the shift has occurred. The OSCTUNE register also implements the INTSRC and PLLEN bits, which control certain features of the internal oscillator block. The INTSRC bit allows users to select which internal oscillator provides the clock source when the 31 kHz frequency option is selected. This is covered in greater detail in Section 2.7.1 "Oscillator Control Register". The PLLEN bit controls the operation of the frequency multiplier, PLL, in internal oscillator modes. 2.6.4 PLL IN INTOSC MODES The 4x frequency multiplier can be used with the internal oscillator block to produce faster device clock speeds than are normally possible with an internal oscillator. When enabled, the PLL produces a clock speed of up to 32 MHz. Unlike HSPLL mode, the PLL is controlled through software. The control bit, PLLEN (OSCTUNE<6>), is used to enable or disable its operation. The PLL is available when the device is configured to use the internal oscillator block as its primary clock source (FOSC<3:0> = 1001 or 1000). Additionally, the PLL will only function when the selected output frequency is either 4 MHz or 8 MHz (OSCCON<6:4> = 111 or 110). If both of these conditions are not met, the PLL is disabled. The PLLEN control bit is only functional in those internal oscillator modes where the PLL is available. In all other modes, it is forced to `0' and is effectively unavailable. 2.6.5 INTOSC FREQUENCY DRIFT The factory calibrates the internal oscillator block output (INTOSC) for 8 MHz. However, this frequency may drift as VDD or temperature changes, which can affect the controller operation in a variety of ways. It is possible to adjust the INTOSC frequency by modifying the value in the OSCTUNE register. This has no effect on the INTRC clock source frequency. Tuning the INTOSC source requires knowing when to make the adjustment, in which direction it should be made, and in some cases, how large a change is needed. Three compensation techniques are discussed in Section 2.6.5.1 "Compensating with the EUSART", Section 2.6.5.2 "Compensating with the Timers" and Section 2.6.5.3 "Compensating with the CCP Module in Capture Mode", but other techniques may be used. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 2-1: OSCTUNE: OSCILLATOR TUNING REGISTER R/W-0 R/W-0(1) U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 INTSRC PLLEN(1) -- TUN4 TUN3 TUN2 TUN1 TUN0 bit 7 bit 0 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 INTSRC: Internal Oscillator Low-Frequency Source Select bit 1 = 31.25 kHz device clock derived from 8 MHz INTOSC source (divide-by-256 enabled) 0 = 31 kHz device clock derived directly from INTRC internal oscillator bit 6 PLLEN: Frequency Multiplier PLL for INTOSC Enable bit(1) 1 = PLL enabled for INTOSC (4 MHz and 8 MHz only) 0 = PLL disabled bit 5 Unimplemented: Read as `0' bit 4-0 TUN<4:0>: Frequency Tuning bits 011111 = Maximum frequency * * * * 000001 000000 = Center frequency. Oscillator module is running at the calibrated frequency. 111111 * * * * 100000 = Minimum frequency Note 1: 2.6.5.1 Available only in certain oscillator configurations; otherwise, this bit is unavailable and reads as `0'. See Section 2.6.4 "PLL in INTOSC Modes" for details. Compensating with the EUSART An adjustment may be required when the EUSART begins to generate framing errors or receives data with errors while in Asynchronous mode. Framing errors indicate that the device clock frequency is too high. To adjust for this, decrement the value in OSCTUNE to reduce the clock frequency. On the other hand, errors in data may suggest that the clock speed is too low. To compensate, increment OSCTUNE to increase the clock frequency. 2.6.5.2 Compensating with the Timers This technique compares device clock speed to some reference clock. Two timers may be used; one timer is clocked by the peripheral clock, while the other is clocked by a fixed reference source, such as the Timer1 oscillator. Both timers are cleared, but the timer clocked by the reference generates interrupts. When an interrupt occurs, the internally clocked timer is read and both timers are cleared. If the internally clocked timer value is greater than expected, then the internal oscillator block is running too fast. To adjust for this, decrement the OSCTUNE register. (c) 2008 Microchip Technology Inc. 2.6.5.3 Compensating with the CCP Module in Capture Mode A CCP module can use free-running Timer1 (or Timer3), clocked by the internal oscillator block and an external event with a known period (i.e., AC power frequency). The time of the first event is captured in the CCPRxH:CCPRxL registers and is recorded for use later. When the second event causes a capture, the time of the first event is subtracted from the time of the second event. Since the period of the external event is known, the time difference between events can be calculated. If the measured time is much greater than the calculated time, the internal oscillator block is running too fast; to compensate, decrement the OSCTUNE register. If the measured time is much less than the calculated time, the internal oscillator block is running too slow; to compensate, increment the OSCTUNE register. DS39631E-page 27 PIC18F2420/2520/4420/4520 2.7 Clock Sources and Oscillator Switching Like previous PIC18 devices, the PIC18F2420/2520/ 4420/4520 family includes a feature that allows the device clock source to be switched from the main oscillator to an alternate low-frequency clock source. PIC18F2420/2520/4420/4520 devices offer two alternate clock sources. When an alternate clock source is enabled, the various power-managed operating modes are available. Essentially, there are three clock sources for these devices: * Primary oscillators * Secondary oscillators * Internal oscillator block The primary oscillators include the External Crystal and Resonator modes, the External RC modes, the External Clock modes and the internal oscillator block. The particular mode is defined by the FOSC<3:0> Configuration bits. The details of these modes are covered earlier in this chapter. FIGURE 2-8: The secondary oscillators are those external sources not connected to the OSC1 or OSC2 pins. These sources may continue to operate even after the controller is placed in a power-managed mode. PIC18F2420/2520/4420/4520 devices offer the Timer1 oscillator as a secondary oscillator. This oscillator, in all power-managed modes, is often the time base for functions such as a Real-Time Clock (RTC). Most often, a 32.768 kHz watch crystal is connected between the RC0/T1OSO/T13CKI and RC1/T1OSI pins. Like the LP Oscillator mode circuit, loading capacitors are also connected from each pin to ground. The Timer1 oscillator is discussed in greater detail in Section 12.3 "Timer1 Oscillator". In addition to being a primary clock source, the internal oscillator block is available as a power-managed mode clock source. The INTRC source is also used as the clock source for several special features, such as the WDT and Fail-Safe Clock Monitor. The clock sources for the PIC18F2420/2520/4420/4520 devices are shown in Figure 2-8. See Section 23.0 "Special Features of the CPU" for Configuration register details. PIC18F2420/2520/4420/4520 CLOCK DIAGRAM PIC18F2420/2520/4420/4520 Primary Oscillator LP, XT, HS, RC, EC OSC2 Sleep 4 x PLL OSC1 OSCTUNE<6> T1OSC T1OSO T1OSCEN Enable Oscillator OSCCON<6:4> INTRC Source 4 MHz 2 MHz 8 MHz (INTOSC) 31 kHz (INTRC) Postscaler Internal Oscillator Block 8 MHz Source 1 MHz 500 kHz 250 kHz 125 kHz Internal Oscillator CPU 111 110 IDLEN 101 100 011 MUX 8 MHz OSCCON<6:4> Peripherals MUX Secondary Oscillator T1OSI HSPLL, INTOSC/PLL 010 001 1 31 kHz 000 0 Clock Control FOSC<3:0> OSCCON<1:0> Clock Source Option for Other Modules OSCTUNE<7> WDT, PWRT, FSCM and Two-Speed Start-up DS39631E-page 28 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 2.7.1 OSCILLATOR CONTROL REGISTER The OSCCON register (Register 2-2) controls several aspects of the device clock's operation, both in full-power operation and in power-managed modes. The System Clock Select bits, SCS<1:0>, select the clock source. The available clock sources are the primary clock (defined by the FOSC<3:0> Configuration bits), the secondary clock (Timer1 oscillator) and the internal oscillator block. The clock source changes immediately after one or more of the bits is written to, following a brief clock transition interval. The SCS bits are cleared on all forms of Reset. The Internal Oscillator Frequency Select bits (IRCF<2:0>) select the frequency output of the internal oscillator block to drive the device clock. The choices are the INTRC source, the INTOSC source (8 MHz) or one of the frequencies derived from the INTOSC postscaler (31.25 kHz to 4 MHz). If the internal oscillator block is supplying the device clock, changing the states of these bits will have an immediate change on the internal oscillator's output. On device Resets, the default output frequency of the internal oscillator block is set at 1 MHz. When a nominal output frequency of 31 kHz is selected (IRCF<2:0> = 000), users may choose which internal oscillator acts as the source. This is done with the INTSRC bit in the OSCTUNE register (OSCTUNE<7>). Setting this bit selects INTOSC as a 31.25 kHz clock source by enabling the divide-by-256 output of the INTOSC postscaler. Clearing INTSRC selects INTRC (nominally 31 kHz) as the clock source. The IDLEN bit determines if the device goes into Sleep mode or one of the Idle modes when the SLEEP instruction is executed. The use of the flag and control bits in the OSCCON register is discussed in more detail in Section 3.0 "Power-Managed Modes". Note 1: The Timer1 oscillator must be enabled to select the secondary clock source. The Timer1 oscillator is enabled by setting the T1OSCEN bit in the Timer1 Control register (T1CON<3>). If the Timer1 oscillator is not enabled, then any attempt to select a secondary clock source will be ignored. 2: It is recommended that the Timer1 oscillator be operating and stable before selecting the secondary clock source or a very long delay may occur while the Timer1 oscillator starts. 2.7.2 OSCILLATOR TRANSITIONS PIC18F2420/2520/4420/4520 devices contain circuitry to prevent clock "glitches" when switching between clock sources. A short pause in the device clock occurs during the clock switch. The length of this pause is the sum of two cycles of the old clock source and three to four cycles of the new clock source. This formula assumes that the new clock source is stable. Clock transitions are discussed in greater detail in Section 3.1.2 "Entering Power-Managed Modes". This option allows users to select the tunable and more precise INTOSC as a clock source, while maintaining power savings with a very low clock speed. Regardless of the setting of INTSRC, INTRC always remains the clock source for features such as the Watchdog Timer and the Fail-Safe Clock Monitor. The OSTS, IOFS and T1RUN bits indicate which clock source is currently providing the device clock. The OSTS bit indicates that the Oscillator Start-up Timer (OST) has timed out and the primary clock is providing the device clock in primary clock modes. The IOFS bit indicates when the internal oscillator block has stabilized and is providing the device clock in RC Clock modes. The T1RUN bit (T1CON<6>) indicates when the Timer1 oscillator is providing the device clock in secondary clock modes. In power-managed modes, only one of these three bits will be set at any time. If none of these bits are set, the INTRC is providing the clock or the internal oscillator block has just started and is not yet stable. (c) 2008 Microchip Technology Inc. DS39631E-page 29 PIC18F2420/2520/4420/4520 REGISTER 2-2: OSCCON: OSCILLATOR CONTROL REGISTER R/W-0 R/W-1 R/W-0 R/W-0 R(1) R-0 R/W-0 R/W-0 IDLEN IRCF2 IRCF1 IRCF0 OSTS IOFS SCS1 SCS0 bit 7 bit 0 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 IDLEN: Idle Enable bit 1 = Device enters an Idle mode on SLEEP instruction 0 = Device enters Sleep mode on SLEEP instruction bit 6-4 IRCF<2:0>: Internal Oscillator Frequency Select bits 111 = 8 MHz (INTOSC drives clock directly) 110 = 4 MHz 101 = 2 MHz 100 = 1 MHz(3) 011 = 500 kHz 010 = 250 kHz 001 = 125 kHz 000 = 31 kHz (from either INTOSC/256 or INTRC directly)(2) bit 3 OSTS: Oscillator Start-up Timer Time-out Status bit(1) 1 = Oscillator Start-up Timer (OST) time-out has expired; primary oscillator is running 0 = Oscillator Start-up Timer (OST) time-out is running; primary oscillator is not ready bit 2 IOFS: INTOSC Frequency Stable bit 1 = INTOSC frequency is stable 0 = INTOSC frequency is not stable bit 1-0 SCS<1:0>: System Clock Select bits 1x = Internal oscillator block 01 = Secondary (Timer1) oscillator 00 = Primary oscillator Note 1: 2: 3: Reset state depends on state of the IESO Configuration bit. Source selected by the INTSRC bit (OSCTUNE<7>), see text. Default output frequency of INTOSC on Reset. DS39631E-page 30 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 2.8 Effects of Power-Managed Modes on the Various Clock Sources When PRI_IDLE mode is selected, the designated primary oscillator continues to run without interruption. For all other power-managed modes, the oscillator using the OSC1 pin is disabled. The OSC1 pin (and OSC2 pin, if used by the oscillator) will stop oscillating. In secondary clock modes (SEC_RUN and SEC_IDLE), the Timer1 oscillator is operating and providing the device clock. The Timer1 oscillator may also run in all power-managed modes if required to clock Timer1 or Timer3. In internal oscillator modes (RC_RUN and RC_IDLE), the internal oscillator block provides the device clock source. The 31 kHz INTRC output can be used directly to provide the clock and may be enabled to support various special features, regardless of the powermanaged mode (see Section 23.2 "Watchdog Timer (WDT)", Section 23.3 "Two-Speed Start-up" and Section 23.4 "Fail-Safe Clock Monitor" for more information on WDT, Fail-Safe Clock Monitor and TwoSpeed Start-up). The INTOSC output at 8 MHz may be used directly to clock the device or may be divided down by the postscaler. The INTOSC output is disabled if the clock is provided directly from the INTRC output. If Sleep mode is selected, all clock sources are stopped. Since all the transistor switching currents have been stopped, Sleep mode achieves the lowest current consumption of the device (only leakage currents). Enabling any on-chip feature that will operate during Sleep will increase the current consumed during Sleep. The INTRC is required to support WDT operation. The Timer1 oscillator may be operating to support a RealTime Clock. Other features may be operating that do TABLE 2-3: not require a device clock source (i.e., MSSP slave, PSP, INTx pins and others). Peripherals that may add significant current consumption are listed in Section 26.2 "DC Characteristics". 2.9 Power-up Delays Power-up delays are controlled by two timers so that no external Reset circuitry is required for most applications. The delays ensure that the device is kept in Reset until the device power supply is stable under normal circumstances and the primary clock is operating and stable. For additional information on power-up delays, see Section 4.5 "Device Reset Timers". The first timer is the Power-up Timer (PWRT), which provides a fixed delay on power-up (parameter 33, Table 26-10). It is enabled by clearing (= 0) the PWRTEN Configuration bit. The second timer is the Oscillator Start-up Timer (OST), intended to keep the chip in Reset until the crystal oscillator is stable (LP, XT and HS modes). The OST does this by counting 1024 oscillator cycles before allowing the oscillator to clock the device. When the HSPLL Oscillator mode is selected, the device is kept in Reset for an additional 2 ms, following the HS mode OST delay, so the PLL can lock to the incoming clock frequency. There is a delay of interval, TCSD (parameter 38, Table 26-10), following POR, while the controller becomes ready to execute instructions. This delay runs concurrently with any other delays. This may be the only delay that occurs when any of the EC, RC or INTIO modes are used as the primary clock source. OSC1 AND OSC2 PIN STATES IN SLEEP MODE OSC Mode OSC1 Pin OSC2 Pin RC, INTIO1 Floating, external resistor should pull high At logic low (clock/4 output) RCIO Floating, external resistor should pull high Configured as PORTA, bit 6 INTIO2 Configured as PORTA, bit 7 Configured as PORTA, bit 6 ECIO Floating, pulled by external clock Configured as PORTA, bit 6 EC Floating, pulled by external clock At logic low (clock/4 output) LP, XT and HS Feedback inverter disabled at quiescent voltage level Feedback inverter disabled at quiescent voltage level Note: See Table 4-2 in Section 4.0 "Reset" for time-outs due to Sleep and MCLR Reset. (c) 2008 Microchip Technology Inc. DS39631E-page 31 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 32 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 3.0 3.1.1 POWER-MANAGED MODES The SCS<1:0> bits allow the selection of one of three clock sources for power-managed modes. They are: PIC18F2420/2520/4420/4520 devices offer a total of seven operating modes for more efficient powermanagement. These modes provide a variety of options for selective power conservation in applications where resources may be limited (i.e., battery-powered devices). * the primary clock, as defined by the FOSC<3:0> Configuration bits * the secondary clock (the Timer1 oscillator) * the internal oscillator block (for RC modes) There are three categories of power-managed modes: 3.1.2 * Run modes * Idle modes * Sleep mode The power-managed modes include several powersaving features offered on previous PIC(R) devices. One is the clock switching feature, offered in other PIC18 devices, allowing the controller to use the Timer1 oscillator in place of the primary oscillator. Also included is the Sleep mode, offered by all PIC devices, where all device clocks are stopped. Entry to the power-managed Idle or Sleep modes is triggered by the execution of a SLEEP instruction. The actual mode that results depends on the status of the IDLEN bit. Depending on the current mode and the mode being switched to, a change to a power-managed mode does not always require setting all of these bits. Many transitions may be done by changing the oscillator select bits, or changing the IDLEN bit, prior to issuing a SLEEP instruction. If the IDLEN bit is already configured correctly, it may only be necessary to perform a SLEEP instruction to switch to the desired mode. Selecting Power-Managed Modes Selecting a power-managed mode requires two decisions: if the CPU is to be clocked or not and the selection of a clock source. The IDLEN bit (OSCCON<7>) controls CPU clocking, while the SCS<1:0> bits (OSCCON<1:0>) select the clock source. The individual modes, bit settings, clock sources and affected modules are summarized in Table 3-1. TABLE 3-1: Mode Sleep ENTERING POWER-MANAGED MODES Switching from one power-managed mode to another begins by loading the OSCCON register. The SCS<1:0> bits select the clock source and determine which Run or Idle mode is to be used. Changing these bits causes an immediate switch to the new clock source, assuming that it is running. The switch may also be subject to clock transition delays. These are discussed in Section 3.1.3 "Clock Transitions and Status Indicators" and subsequent sections. These categories define which portions of the device are clocked and sometimes, what speed. The Run and Idle modes may use any of the three available clock sources (primary, secondary or internal oscillator block); the Sleep mode does not use a clock source. 3.1 CLOCK SOURCES POWER-MANAGED MODES OSCCON<7,1:0> Bits Module Clocking IDLEN(1) SCS<1:0> CPU Available Clock and Oscillator Source Peripherals 0 N/A Off Off PRI_RUN N/A 00 Clocked Clocked Primary - LP, XT, HS, HSPLL, RC, EC and Internal Oscillator Block(2). This is the normal full-power execution mode. SEC_RUN N/A 01 Clocked Clocked Secondary - Timer1 Oscillator RC_RUN N/A 1x Clocked Clocked Internal Oscillator Block(2) PRI_IDLE 1 00 Off Clocked Primary - LP, XT, HS, HSPLL, RC, EC SEC_IDLE 1 01 Off Clocked Secondary - Timer1 Oscillator RC_IDLE 1 1x Off Clocked Internal Oscillator Block(2) Note 1: 2: None - All clocks are disabled IDLEN reflects its value when the SLEEP instruction is executed. Includes INTOSC and INTOSC postscaler, as well as the INTRC source. (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 33 PIC18F2420/2520/4420/4520 3.1.3 CLOCK TRANSITIONS AND STATUS INDICATORS The length of the transition between clock sources is the sum of two cycles of the old clock source and three to four cycles of the new clock source. This formula assumes that the new clock source is stable. Three bits indicate the current clock source and its status. They are: * OSTS (OSCCON<3>) * IOFS (OSCCON<2>) * T1RUN (T1CON<6>) In general, only one of these bits will be set while in a given power-managed mode. When the OSTS bit is set, the primary clock is providing the device clock. When the IOFS bit is set, the INTOSC output is providing a stable 8 MHz clock source to a divider that actually drives the device clock. When the T1RUN bit is set, the Timer1 oscillator is providing the clock. If none of these bits are set, then either the INTRC clock source is clocking the device or the INTOSC source is not yet stable. If the internal oscillator block is configured as the primary clock source by the FOSC<3:0> Configuration bits, then both the OSTS and IOFS bits may be set when in PRI_RUN or PRI_IDLE modes. This indicates that the primary clock (INTOSC output) is generating a stable 8 MHz output. Entering another power-managed RC mode at the same frequency would clear the OSTS bit. 3.2 Run Modes In the Run modes, clocks to both the core and peripherals are active. The difference between these modes is the clock source. 3.2.1 The PRI_RUN mode is the normal, full-power execution mode of the microcontroller. This is also the default mode upon a device Reset unless Two-Speed Start-up is enabled (see Section 23.3 "Two-Speed Start-up" for details). In this mode, the OSTS bit is set. The IOFS bit may be set if the internal oscillator block is the primary clock source (see Section 2.7.1 "Oscillator Control Register"). 3.2.2 3.1.4 MULTIPLE SLEEP COMMANDS The power-managed mode that is invoked with the SLEEP instruction is determined by the setting of the IDLEN bit at the time the instruction is executed. If another SLEEP instruction is executed, the device will enter the power-managed mode specified by IDLEN at that time. If IDLEN has changed, the device will enter the new power-managed mode specified by the new setting. DS39631E-page 34 SEC_RUN MODE The SEC_RUN mode is the compatible mode to the "clock switching" feature offered in other PIC18 devices. In this mode, the CPU and peripherals are clocked from the Timer1 oscillator. This gives users the option of lower power consumption while still using a high-accuracy clock source. SEC_RUN mode is entered by setting the SCS<1:0> bits to `01'. The device clock source is switched to the Timer1 oscillator (see Figure 3-1), the primary oscillator is shut down, the T1RUN bit (T1CON<6>) is set and the OSTS bit is cleared. Note: Note 1: Caution should be used when modifying a single IRCF bit. If VDD is less than 3V, it is possible to select a higher clock speed than is supported by the low VDD. Improper device operation may result if the VDD/FOSC specifications are violated. 2: Executing a SLEEP instruction does not necessarily place the device into Sleep mode. It acts as the trigger to place the controller into either the Sleep mode or one of the Idle modes, depending on the setting of the IDLEN bit. PRI_RUN MODE The Timer1 oscillator should already be running prior to entering SEC_RUN mode. If the T1OSCEN bit is not set when the SCS<1:0> bits are set to `01', entry to SEC_RUN mode will not occur. If the Timer1 oscillator is enabled, but not yet running, device clocks will be delayed until the oscillator has started. In such situations, initial oscillator operation is far from stable and unpredictable operation may result. On transitions from SEC_RUN mode to PRI_RUN mode, the peripherals and CPU continue to be clocked from the Timer1 oscillator while the primary clock is started. When the primary clock becomes ready, a clock switch back to the primary clock occurs (see Figure 3-2). When the clock switch is complete, the T1RUN bit is cleared, the OSTS bit is set and the primary clock is providing the clock. The IDLEN and SCS bits are not affected by the wake-up; the Timer1 oscillator continues to run. Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 3-1: TRANSITION TIMING FOR ENTRY TO SEC_RUN MODE Q1 Q2 Q3 Q4 Q1 Q2 1 T1OSI 2 3 n-1 Q3 Q4 Q1 Q2 Q3 n Clock Transition(1) OSC1 CPU Clock Peripheral Clock Program Counter PC PC + 2 PC + 4 Note 1: Clock transition typically occurs within 2-4 TOSC. FIGURE 3-2: TRANSITION TIMING FROM SEC_RUN MODE TO PRI_RUN MODE (HSPLL) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 T1OSI OSC1 TOST(1) TPLL(1) 1 PLL Clock Output 2 n-1 n Clock Transition(2) CPU Clock Peripheral Clock Program Counter PC + 2 PC SCS<1:0> bits Changed PC + 4 OSTS bit Set Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. 2: Clock transition typically occurs within 2-4 TOSC. 3.2.3 RC_RUN MODE In RC_RUN mode, the CPU and peripherals are clocked from the internal oscillator block using the INTOSC multiplexer. In this mode, the primary clock is shut down. When using the INTRC source, this mode provides the best power conservation of all the Run modes while still executing code. It works well for user applications which are not highly timing sensitive or do not require high-speed clocks at all times. This mode is entered by setting the SCS1 bit to `1'. Although it is ignored, it is recommended that the SCS0 bit also be cleared; this is to maintain software compatibility with future devices. When the clock source is switched to the INTOSC multiplexer (see Figure 3-3), the primary oscillator is shut down and the OSTS bit is cleared. The IRCF bits may be modified at any time to immediately change the clock speed. Note: If the primary clock source is the internal oscillator block (either INTRC or INTOSC), there are no distinguishable differences between PRI_RUN and RC_RUN modes during execution. However, a clock switch delay will occur during entry to and exit from RC_RUN mode. Therefore, if the primary clock source is the internal oscillator block, the use of RC_RUN mode is not recommended. (c) 2008 Microchip Technology Inc. Advance Information Caution should be used when modifying a single IRCF bit. If VDD is less than 3V, it is possible to select a higher clock speed than is supported by the low VDD. Improper device operation may result if the VDD/FOSC specifications are violated. DS39631E-page 35 PIC18F2420/2520/4420/4520 If the IRCF bits and the INTSRC bit are all clear, the INTOSC output is not enabled and the IOFS bit will remain clear; there will be no indication of the current clock source. The INTRC source is providing the device clocks. On transitions from RC_RUN mode to PRI_RUN mode, the device continues to be clocked from the INTOSC multiplexer while the primary clock is started. When the primary clock becomes ready, a clock switch to the primary clock occurs (see Figure 3-4). When the clock switch is complete, the IOFS bit is cleared, the OSTS bit is set and the primary clock is providing the device clock. The IDLEN and SCS bits are not affected by the switch. The INTRC source will continue to run if either the WDT or the Fail-Safe Clock Monitor is enabled. If the IRCF bits are changed from all clear (thus, enabling the INTOSC output), or if INTSRC is set, the IOFS bit becomes set after the INTOSC output becomes stable. Clocks to the device continue while the INTOSC source stabilizes after an interval of TIOBST. If the IRCF bits were previously at a non-zero value, or if INTSRC was set before setting SCS1 and the INTOSC source was already stable, the IOFS bit will remain set. FIGURE 3-3: TRANSITION TIMING TO RC_RUN MODE Q1 Q2 Q3 Q4 Q1 Q2 1 INTRC 2 3 n-1 Q3 Q4 Q1 Q2 Q3 n (1) Clock Transition OSC1 CPU Clock Peripheral Clock Program Counter PC PC + 2 PC + 4 Note 1: Clock transition typically occurs within 2-4 TOSC. FIGURE 3-4: TRANSITION TIMING FROM RC_RUN MODE TO PRI_RUN MODE Q1 Q2 Q3 Q4 Q2 Q3 Q4 Q1 Q2 Q3 Q1 INTOSC Multiplexer OSC1 TOST(1) TPLL(1) 1 PLL Clock Output 2 n-1 n Clock Transition(2) CPU Clock Peripheral Clock Program Counter PC + 2 PC SCS<1:0> bits Changed PC + 4 OSTS bit Set Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. 2: Clock transition typically occurs within 2-4 TOSC. DS39631E-page 36 Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 3.3 Sleep Mode 3.4 The power-managed Sleep mode in the PIC18F2420/ 2520/4420/4520 devices is identical to the legacy Sleep mode offered in all other PIC devices. It is entered by clearing the IDLEN bit (the default state on device Reset) and executing the SLEEP instruction. This shuts down the selected oscillator (Figure 3-5). All clock source status bits are cleared. Idle Modes The Idle modes allow the controller's CPU to be selectively shut down while the peripherals continue to operate. Selecting a particular Idle mode allows users to further manage power consumption. If the IDLEN bit is set to `1' when a SLEEP instruction is executed, the peripherals will be clocked from the clock source selected using the SCS<1:0> bits; however, the CPU will not be clocked. The clock source status bits are not affected. Setting IDLEN and executing a SLEEP instruction provides a quick method of switching from a given Run mode to its corresponding Idle mode. Entering the Sleep mode from any other mode does not require a clock switch. This is because no clocks are needed once the controller has entered Sleep. If the WDT is selected, the INTRC source will continue to operate. If the Timer1 oscillator is enabled, it will also continue to run. If the WDT is selected, the INTRC source will continue to operate. If the Timer1 oscillator is enabled, it will also continue to run. When a wake event occurs in Sleep mode (by interrupt, Reset or WDT time-out), the device will not be clocked until the clock source selected by the SCS<1:0> bits becomes ready (see Figure 3-6), or it will be clocked from the internal oscillator block if either the Two-Speed Start-up or the Fail-Safe Clock Monitor are enabled (see Section 23.0 "Special Features of the CPU"). In either case, the OSTS bit is set when the primary clock is providing the device clocks. The IDLEN and SCS bits are not affected by the wake-up. Since the CPU is not executing instructions, the only exits from any of the Idle modes are by interrupt, WDT time-out or a Reset. When a wake event occurs, CPU execution is delayed by an interval of TCSD (parameter 38, Table 26-10) while it becomes ready to execute code. When the CPU begins executing code, it resumes with the same clock source for the current Idle mode. For example, when waking from RC_IDLE mode, the internal oscillator block will clock the CPU and peripherals (in other words, RC_RUN mode). The IDLEN and SCS bits are not affected by the wake-up. While in any Idle mode or the Sleep mode, a WDT time-out will result in a WDT wake-up to the Run mode currently specified by the SCS1:SCS0 bits. FIGURE 3-5: TRANSITION TIMING FOR ENTRY TO SLEEP MODE Q1 Q2 Q3 Q4 Q1 OSC1 CPU Clock Peripheral Clock Sleep Program Counter PC FIGURE 3-6: PC + 2 TRANSITION TIMING FOR WAKE FROM SLEEP (HSPLL) Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 OSC1 TOST(1) PLL Clock Output TPLL(1) CPU Clock Peripheral Clock Program Counter PC Wake Event PC + 2 PC + 4 PC + 6 OSTS bit Set Note1: TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 37 PIC18F2420/2520/4420/4520 3.4.1 PRI_IDLE MODE This mode is unique among the three low-power Idle modes in that it does not disable the primary device clock. For timing-sensitive applications, this allows for the fastest resumption of device operation with its more accurate primary clock source, since the clock source does not have to "warm-up" or transition from another oscillator. PRI_IDLE mode is entered from PRI_RUN mode by setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, set IDLEN first, then clear the SCS bits and execute SLEEP. Although the CPU is disabled, the peripherals continue to be clocked from the primary clock source specified by the FOSC<3:0> Configuration bits. The OSTS bit remains set (see Figure 3-7). setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, set the IDLEN bit first, then set the SCS<1:0> bits to `01' and execute SLEEP. When the clock source is switched to the Timer1 oscillator, the primary oscillator is shut down, the OSTS bit is cleared and the T1RUN bit is set. When a wake event occurs, the peripherals continue to be clocked from the Timer1 oscillator. After an interval of TCSD, following the wake event, the CPU begins executing code being clocked by the Timer1 oscillator. The IDLEN and SCS bits are not affected by the wake-up; the Timer1 oscillator continues to run (see Figure 3-8). Note: When a wake event occurs, the CPU is clocked from the primary clock source. A delay of interval TCSD is required between the wake event and when code execution starts. This is required to allow the CPU to become ready to execute instructions. After the wakeup, the OSTS bit remains set. The IDLEN and SCS bits are not affected by the wake-up (see Figure 3-8). 3.4.2 The Timer1 oscillator should already be running prior to entering SEC_IDLE mode. If the T1OSCEN bit is not set when the SLEEP instruction is executed, the SLEEP instruction will be ignored and entry to SEC_IDLE mode will not occur. If the Timer1 oscillator is enabled but not yet running, peripheral clocks will be delayed until the oscillator has started. In such situations, initial oscillator operation is far from stable and unpredictable operation may result. SEC_IDLE MODE In SEC_IDLE mode, the CPU is disabled but the peripherals continue to be clocked from the Timer1 oscillator. This mode is entered from SEC_RUN by FIGURE 3-7: TRANSITION TIMING FOR ENTRY TO IDLE MODE Q1 Q3 Q2 Q4 Q1 OSC1 CPU Clock Peripheral Clock Program Counter PC FIGURE 3-8: PC + 2 TRANSITION TIMING FOR WAKE FROM IDLE TO RUN MODE Q1 Q2 Q3 Q4 OSC1 TCSD CPU Clock Peripheral Clock Program Counter PC Wake Event DS39631E-page 38 Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 3.4.3 RC_IDLE MODE In RC_IDLE mode, the CPU is disabled but the peripherals continue to be clocked from the internal oscillator block using the INTOSC multiplexer. This mode allows for controllable power conservation during Idle periods. From RC_RUN, this mode is entered by setting the IDLEN bit and executing a SLEEP instruction. If the device is in another Run mode, first set IDLEN, then set the SCS1 bit and execute SLEEP. Although its value is ignored, it is recommended that SCS0 also be cleared; this is to maintain software compatibility with future devices. The INTOSC multiplexer may be used to select a higher clock frequency by modifying the IRCF bits before executing the SLEEP instruction. When the clock source is switched to the INTOSC multiplexer, the primary oscillator is shut down and the OSTS bit is cleared. If the IRCF bits are set to any non-zero value, or the INTSRC bit is set, the INTOSC output is enabled. The IOFS bit becomes set, after the INTOSC output becomes stable, after an interval of TIOBST (parameter 39, Table 26-10). Clocks to the peripherals continue while the INTOSC source stabilizes. If the IRCF bits were previously at a non-zero value, or INTSRC was set before the SLEEP instruction was executed and the INTOSC source was already stable, the IOFS bit will remain set. If the IRCF bits and INTSRC are all clear, the INTOSC output will not be enabled, the IOFS bit will remain clear and there will be no indication of the current clock source. When a wake event occurs, the peripherals continue to be clocked from the INTOSC multiplexer. After a delay of TCSD following the wake event, the CPU begins executing code being clocked by the INTOSC multiplexer. The IDLEN and SCS bits are not affected by the wake-up. The INTRC source will continue to run if either the WDT or the Fail-Safe Clock Monitor is enabled. 3.5 Exiting Idle and Sleep Modes An exit from Sleep mode or any of the Idle modes is triggered by an interrupt, a Reset or a WDT time-out. This section discusses the triggers that cause exits from power-managed modes. The clocking subsystem actions are discussed in each of the power-managed modes (see Section 3.2 "Run Modes", Section 3.3 "Sleep Mode" and Section 3.4 "Idle Modes"). 3.5.1 EXIT BY INTERRUPT Any of the available interrupt sources can cause the device to exit from an Idle mode or the Sleep mode to a Run mode. To enable this functionality, an interrupt source must be enabled by setting its enable bit in one of the INTCON or PIE registers. The exit sequence is initiated when the corresponding interrupt flag bit is set. (c) 2008 Microchip Technology Inc. On all exits from Idle or Sleep modes by interrupt, code execution branches to the interrupt vector if the GIE/ GIEH bit (INTCON<7>) is set. Otherwise, code execution continues or resumes without branching (see Section 9.0 "Interrupts"). A fixed delay of interval TCSD following the wake event is required when leaving Sleep and Idle modes. This delay is required for the CPU to prepare for execution. Instruction execution resumes on the first clock cycle following this delay. 3.5.2 EXIT BY WDT TIME-OUT A WDT time-out will cause different actions depending on which power-managed mode the device is in when the time-out occurs. If the device is not executing code (all Idle modes and Sleep mode), the time-out will result in an exit from the power-managed mode (see Section 3.2 "Run Modes" and Section 3.3 "Sleep Mode"). If the device is executing code (all Run modes), the time-out will result in a WDT Reset (see Section 23.2 "Watchdog Timer (WDT)"). The WDT timer and postscaler are cleared by executing a SLEEP or CLRWDT instruction, the loss of a currently selected clock source (if the Fail-Safe Clock Monitor is enabled) and modifying the IRCF bits in the OSCCON register if the internal oscillator block is the device clock source. 3.5.3 EXIT BY RESET Normally, the device is held in Reset by the Oscillator Start-up Timer (OST) until the primary clock becomes ready. At that time, the OSTS bit is set and the device begins executing code. If the internal oscillator block is the new clock source, the IOFS bit is set instead. The exit delay time from Reset to the start of code execution depends on both the clock sources before and after the wake-up and the type of oscillator if the new clock source is the primary clock. Exit delays are summarized in Table 3-2. Code execution can begin before the primary clock becomes ready. If either the Two-Speed Start-up (see Section 23.3 "Two-Speed Start-up") or Fail-Safe Clock Monitor (see Section 23.4 "Fail-Safe Clock Monitor") is enabled, the device may begin execution as soon as the Reset source has cleared. Execution is clocked by the INTOSC multiplexer driven by the internal oscillator block. Execution is clocked by the internal oscillator block until either the primary clock becomes ready or a power-managed mode is entered before the primary clock becomes ready; the primary clock is then shut down. Advance Information DS39631E-page 39 PIC18F2420/2520/4420/4520 3.5.4 EXIT WITHOUT AN OSCILLATOR START-UP DELAY Certain exits from power-managed modes do not invoke the OST at all. There are two cases: * PRI_IDLE mode, where the primary clock source is not stopped and * the primary clock source is not any of the LP, XT, HS or HSPLL modes. TABLE 3-2: In these instances, the primary clock source either does not require an oscillator start-up delay, since it is already running (PRI_IDLE), or normally does not require an oscillator start-up delay (RC, EC and INTIO Oscillator modes). However, a fixed delay of interval TCSD following the wake event is still required when leaving Sleep and Idle modes to allow the CPU to prepare for execution. Instruction execution resumes on the first clock cycle following this delay. EXIT DELAY ON WAKE-UP BY RESET FROM SLEEP MODE OR ANY IDLE MODE (BY CLOCK SOURCES) Clock Source Before Wake-up Clock Source After Wake-up Exit Delay Clock Ready Status Bit (OSCCON) LP, XT, HS Primary Device Clock (PRI_IDLE mode) HSPLL EC, RC TCSD(1) INTOSC(2) T1OSC or INTRC(1) INTOSC(2) None (Sleep mode) Note 1: 2: 3: OSTS IOFS LP, XT, HS TOST(3) HSPLL TOST + trc(3) OSTS EC, RC INTOSC(2) TCSD(1) TCSD(1) IOFS LP, XT, HS TOST(3) HSPLL TOST + trc(3) EC, RC TCSD(1) INTOSC(2) TCSD(1) LP, XT, HS TOST(3) HSPLL TOST + trc(3) EC, RC TCSD(1) INTOSC(2) TCSD(1) OSTS IOFS OSTS IOFS TCSD (parameter 38) is a required delay when waking from Sleep and all Idle modes and runs concurrently with any other required delays (see Section 3.4 "Idle Modes"). On Reset, INTOSC defaults to 1 MHz. Includes both the INTOSC 8 MHz source and postscaler derived frequencies. TOST is the Oscillator Start-up Timer (parameter 32). trc is the PLL lock-out timer (parameter F12); it is also designated as TPLL. DS39631E-page 40 Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 4.0 RESET The PIC18F2420/2520/4420/4520 devices differentiate between various kinds of Reset: a) b) c) d) e) f) g) h) Power-on Reset (POR) MCLR Reset during normal operation MCLR Reset during power-managed modes Watchdog Timer (WDT) Reset (during execution) Programmable Brown-out Reset (BOR) RESET Instruction Stack Full Reset Stack Underflow Reset This section discusses Resets generated by MCLR, POR and BOR and covers the operation of the various start-up timers. Stack Reset events are covered in Section 5.1.2.4 "Stack Full and Underflow Resets". WDT Resets are covered in Section 23.2 "Watchdog Timer (WDT)". FIGURE 4-1: A simplified block diagram of the On-Chip Reset Circuit is shown in Figure 4-1. 4.1 RCON Register Device Reset events are tracked through the RCON register (Register 4-1). The lower five bits of the register indicate that a specific Reset event has occurred. In most cases, these bits can only be cleared by the event and must be set by the application after the event. The state of these flag bits, taken together, can be read to indicate the type of Reset that just occurred. This is described in more detail in Section 4.6 "Reset State of Registers". The RCON register also has control bits for setting interrupt priority (IPEN) and software control of the BOR (SBOREN). Interrupt priority is discussed in Section 9.0 "Interrupts". BOR is covered in Section 4.4 "Brown-out Reset (BOR)". SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT RESET Instruction Stack Full/Underflow Reset Stack Pointer External Reset MCLRE MCLR ( )_IDLE Sleep WDT Time-out VDD Rise Detect POR Pulse VDD Brown-out Reset BOREN S OST/PWRT OST 1024 Cycles 10-Bit Ripple Counter OSC1 32 s INTRC(1) PWRT Chip_Reset R Q 65.5 ms 11-Bit Ripple Counter Enable PWRT Enable OST(2) Note 1: 2: This is the INTRC source from the internal oscillator block and is separate from the RC oscillator of the CLKI pin. See Table 4-2 for time-out situations. (c) 2008 Microchip Technology Inc. DS39631E-page 41 PIC18F2420/2520/4420/4520 REGISTER 4-1: RCON: RESET CONTROL REGISTER R/W-0 R/W-1(1) U-0 R/W-1 R-1 R-1 R/W-0(2) R/W-0 IPEN SBOREN -- RI TO PD POR BOR 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 IPEN: Interrupt Priority Enable bit 1 = Enable priority levels on interrupts 0 = Disable priority levels on interrupts (PIC16CXXX Compatibility mode) bit 6 SBOREN: BOR Software Enable bit(1) If BOREN1:BOREN0 = 01: 1 = BOR is enabled 0 = BOR is disabled If BOREN1:BOREN0 = 00, 10 or 11: Bit is disabled and read as `0'. bit 5 Unimplemented: Read as `0' bit 4 RI: RESET Instruction Flag bit 1 = The RESET instruction was not executed (set by firmware only) 0 = The RESET instruction was executed causing a device Reset (must be set in software after a Brown-out Reset occurs) bit 3 TO: Watchdog Time-out Flag bit 1 = Set by power-up, CLRWDT instruction or SLEEP instruction 0 = A WDT time-out occurred bit 2 PD: Power-Down Detection Flag bit 1 = Set by power-up or by the CLRWDT instruction 0 = Set by execution of the SLEEP instruction bit 1 POR: Power-on Reset Status bit 1 = A Power-on Reset has not occurred (set by firmware only) 0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs) bit 0 BOR: Brown-out Reset Status bit 1 = A Brown-out Reset has not occurred (set by firmware only) 0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs) Note 1: 2: If SBOREN is enabled, its Reset state is `1'; otherwise, it is `0'. The actual Reset value of POR is determined by the type of device Reset. See the notes following this register and Section 4.6 "Reset State of Registers" for additional information. Note 1: It is recommended that the POR bit be set after a Power-on Reset has been detected so that subsequent Power-on Resets may be detected. 2: Brown-out Reset is said to have occurred when BOR is `0' and POR is `1' (assuming that POR was set to `1' by software immediately after a Power-on Reset). DS39631E-page 42 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 4.2 Master Clear (MCLR) The MCLR pin provides a method for triggering an external Reset of the device. A Reset is generated by holding the pin low. These devices have a noise filter in the MCLR Reset path which detects and ignores small pulses. FIGURE 4-2: In PIC18F2420/2520/4420/4520 devices, the MCLR input can be disabled with the MCLRE Configuration bit. When MCLR is disabled, the pin becomes a digital input. See Section 10.5 "PORTE, TRISE and LATE Registers" for more information. 4.3 D To take advantage of the POR circuitry, tie the MCLR pin through a resistor (1 k to 10 k) to VDD. This will eliminate external RC components usually needed to create a Power-on Reset delay. A minimum rise rate for VDD is specified (parameter D004). For a slow rise time, see Figure 4-2. R R1 C MCLR PIC18FXXXX Note 1: External Power-on Reset circuit is required only if the VDD power-up slope is too slow. The diode D helps discharge the capacitor quickly when VDD powers down. 2: R < 40 k is recommended to make sure that the voltage drop across R does not violate the device's electrical specification. 3: R1 1 k will limit any current flowing into MCLR from external capacitor C, in the event of MCLR/VPP pin breakdown, due to Electrostatic Discharge (ESD) or Electrical Overstress (EOS). Power-on Reset (POR) A Power-on Reset pulse is generated on-chip whenever VDD rises above a certain threshold. This allows the device to start in the initialized state when VDD is adequate for operation. VDD VDD The MCLR pin is not driven low by any internal Resets, including the WDT. EXTERNAL POWER-ON RESET CIRCUIT (FOR SLOW VDD POWER-UP) When the device starts normal operation (i.e., exits the Reset condition), device operating parameters (voltage, frequency, temperature, etc.) must be met to ensure operation. If these conditions are not met, the device must be held in Reset until the operating conditions are met. POR events are captured by the POR bit (RCON<1>). The state of the bit is set to `0' whenever a POR occurs; it does not change for any other Reset event. POR is not reset to `1' by any hardware event. To capture multiple events, the user manually resets the bit to `1' in software following any POR. (c) 2008 Microchip Technology Inc. DS39631E-page 43 PIC18F2420/2520/4420/4520 4.4 Brown-out Reset (BOR) PIC18F2420/2520/4420/4520 devices implement a BOR circuit that provides the user with a number of configuration and power-saving options. The BOR is controlled by the BORV<1:0> and BOREN<1:0> Configuration bits. There are a total of four BOR configurations which are summarized in Table 4-1. The BOR threshold is set by the BORV<1:0> bits. If BOR is enabled (any values of BOREN<1:0>, except `00'), any drop of VDD below VBOR (parameter D005) for greater than TBOR (parameter 35) will reset the device. A Reset may or may not occur if VDD falls below VBOR for less than TBOR. The chip will remain in Brown-out Reset until VDD rises above VBOR. If the Power-up Timer is enabled, it will be invoked after VDD rises above VBOR; it then will keep the chip in Reset for an additional time delay, TPWRT (parameter 33). If VDD drops below VBOR while the Power-up Timer is running, the chip will go back into a Brown-out Reset and the Power-up Timer will be initialized. Once VDD rises above VBOR, the Power-up Timer will execute the additional time delay. BOR and the Power-up Timer (PWRT) are independently configured. Enabling the Brown-out Reset does not automatically enable the PWRT. 4.4.1 SOFTWARE ENABLED BOR When BOREN<1:0> = 01, the BOR can be enabled or disabled by the user in software. This is done with the control bit, SBOREN (RCON<6>). Setting SBOREN enables the BOR to function as previously described. Clearing SBOREN disables the BOR entirely. The SBOREN bit operates only in this mode; otherwise it is read as `0'. TABLE 4-1: Placing the BOR under software control gives the user the additional flexibility of tailoring the application to its environment without having to reprogram the device to change BOR configuration. It also allows the user to tailor device power consumption in software by eliminating the incremental current that the BOR consumes. While the BOR current is typically very small, it may have some impact in low-power applications. Note: 4.4.2 Even when BOR is under software control, the Brown-out Reset voltage level is still set by the BORV<1:0> Configuration bits; it cannot be changed in software. DETECTING BOR When BOR is enabled, the BOR bit always resets to `0' on any BOR or POR event. This makes it difficult to determine if a BOR event has occurred just by reading the state of BOR alone. A more reliable method is to simultaneously check the state of both POR and BOR. This assumes that the POR bit is reset to `1' in software immediately after any POR event. If BOR is `0' while POR is `1', it can be reliably assumed that a BOR event has occurred. 4.4.3 DISABLING BOR IN SLEEP MODE When BOREN<1:0> = 10, the BOR remains under hardware control and operates as previously described. Whenever the device enters Sleep mode, however, the BOR is automatically disabled. When the device returns to any other operating mode, BOR is automatically re-enabled. This mode allows for applications to recover from brown-out situations, while actively executing code, when the device requires BOR protection the most. At the same time, it saves additional power in Sleep mode by eliminating the small incremental BOR current. BOR CONFIGURATIONS BOR Configuration BOREN1 BOREN0 Status of SBOREN (RCON<6>) 0 0 Unavailable 0 1 Available 1 0 Unavailable BOR enabled in hardware in Run and Idle modes, disabled during Sleep mode. 1 1 Unavailable BOR enabled in hardware; must be disabled by reprogramming the Configuration bits. DS39631E-page 44 BOR Operation BOR disabled; must be enabled by reprogramming the Configuration bits. BOR enabled in software; operation controlled by SBOREN. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 4.5 4.5.3 Device Reset Timers PIC18F2420/2520/4420/4520 devices incorporate three separate on-chip timers that help regulate the Power-on Reset process. Their main function is to ensure that the device clock is stable before code is executed. These timers are: * Power-up Timer (PWRT) * Oscillator Start-up Timer (OST) * PLL Lock Time-out 4.5.1 With the PLL enabled in its PLL mode, the time-out sequence following a Power-on Reset is slightly different from other oscillator modes. A separate timer is used to provide a fixed time-out that is sufficient for the PLL to lock to the main oscillator frequency. This PLL lock time-out (TPLL) is typically 2 ms and follows the oscillator start-up time-out. 4.5.4 TIME-OUT SEQUENCE On power-up, the time-out sequence is as follows: POWER-UP TIMER (PWRT) The Power-up Timer (PWRT) of PIC18F2420/2520/ 4420/4520 devices is an 11-bit counter which uses the INTRC source as the clock input. This yields an approximate time interval of 2048 x 32 s = 65.6 ms. While the PWRT is counting, the device is held in Reset. The power-up time delay depends on the INTRC clock and will vary from chip to chip due to temperature and process variation. See DC parameter 33 for details. The PWRT is enabled by clearing the PWRTEN Configuration bit. 4.5.2 PLL LOCK TIME-OUT OSCILLATOR START-UP TIMER (OST) The Oscillator Start-up Timer (OST) provides a 1024 oscillator cycle (from OSC1 input) delay after the PWRT delay is over (parameter 33). This ensures that the crystal oscillator or resonator has started and stabilized. 1. 2. After the POR pulse has cleared, PWRT time-out is invoked (if enabled). Then, the OST is activated. The total time-out will vary based on oscillator configuration and the status of the PWRT. Figure 4-3, Figure 4-4, Figure 4-5, Figure 4-6 and Figure 4-7 all depict time-out sequences on power-up, with the Power-up Timer enabled and the device operating in HS Oscillator mode. Figure 4-3 through Figure 4-6 also apply to devices operating in XT or LP modes. For devices in RC mode and with the PWRT disabled, on the other hand, there will be no time-out at all. Since the time-outs occur from the POR pulse, if MCLR is kept low long enough, all time-outs will expire. Bringing MCLR high will begin execution immediately (Figure 4-5). This is useful for testing purposes or to synchronize more than one PIC18FXXXX device operating in parallel. The OST time-out is invoked only for XT, LP, HS and HSPLL modes and only on Power-on Reset, or on exit from most power-managed modes. TABLE 4-2: TIME-OUT IN VARIOUS SITUATIONS Power-up(2) and Brown-out Oscillator Configuration HSPLL PWRTEN = 0 66 ms(1) + 1024 TOSC + 2 ms(2) PWRTEN = 1 Exit from Power-Managed Mode 1024 TOSC + 2 ms(2) 1024 TOSC + 2 ms(2) HS, XT, LP 66 ms(1) + 1024 TOSC 1024 TOSC 1024 TOSC EC, ECIO 66 ms(1) -- -- RC, RCIO ms(1) -- -- (1) -- -- INTIO1, INTIO2 66 66 ms Note 1: 66 ms (65.5 ms) is the nominal Power-up Timer (PWRT) delay. 2: 2 ms is the nominal time required for the PLL to lock. (c) 2008 Microchip Technology Inc. DS39631E-page 45 PIC18F2420/2520/4420/4520 FIGURE 4-3: TIME-OUT SEQUENCE ON POWER-UP (MCLR TIED TO VDD, VDD RISE < TPWRT) VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET FIGURE 4-4: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 1 VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET FIGURE 4-5: TIME-OUT SEQUENCE ON POWER-UP (MCLR NOT TIED TO VDD): CASE 2 VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET DS39631E-page 46 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 4-6: SLOW RISE TIME (MCLR TIED TO VDD, VDD RISE > TPWRT) 5V VDD 0V MCLR INTERNAL POR TPWRT PWRT TIME-OUT TOST OST TIME-OUT INTERNAL RESET TIME-OUT SEQUENCE ON POR W/PLL ENABLED (MCLR TIED TO VDD) FIGURE 4-7: VDD MCLR INTERNAL POR TPWRT PWRT TIME-OUT OST TIME-OUT TOST TPLL PLL TIME-OUT INTERNAL RESET Note: TOST = 1024 clock cycles. TPLL 2 ms max. First three stages of the PWRT timer. (c) 2008 Microchip Technology Inc. DS39631E-page 47 PIC18F2420/2520/4420/4520 4.6 Table 4-4 describes the Reset states for all of the Special Function Registers. These are categorized by Power-on and Brown-out Resets, Master Clear and WDT Resets and WDT wake-ups. Reset State of Registers Most registers are unaffected by a Reset. Their status is unknown on POR and unchanged by all other Resets. The other registers are forced to a "Reset state" depending on the type of Reset that occurred. Most registers are not affected by a WDT wake-up, since this is viewed as the resumption of normal operation. Status bits from the RCON register, RI, TO, PD, POR and BOR, are set or cleared differently in different Reset situations, as indicated in Table 4-3. These bits are used in software to determine the nature of the Reset. TABLE 4-3: STATUS BITS, THEIR SIGNIFICANCE AND THE INITIALIZATION CONDITION FOR RCON REGISTER RCON Register STKPTR Register Program Counter RI TO PD POR BOR STKFUL STKUNF Power-on Reset 0000h 1 1 1 0 0 0 0 RESET Instruction 0000h 0 u u u u u u Brown-out Reset 0000h 1 1 1 u 0 u u MCLR Reset during Power-Managed Run Modes 0000h u 1 u u u u u MCLR Reset during Power-Managed Idle Modes and Sleep Mode 0000h u 1 0 u u u u WDT Time-out during Full Power or Power-Managed Run Mode 0000h u 0 u u u u u MCLR Reset during Full-Power Execution 0000h u u u u u u u Condition Stack Full Reset (STVREN = 1) 0000h u u u u u 1 u Stack Underflow Reset (STVREN = 1) 0000h u u u u u u 1 Stack Underflow Error (not an actual Reset, STVREN = 0) 0000h u u u u u u 1 WDT Time-out during Power-Managed Idle or Sleep Modes PC + 2 u 0 0 u u u u PC + 2(1) u u 0 u u u u Interrupt Exit from Power-Managed Modes Legend: u = unchanged Note 1: When the wake-up is due to an interrupt and the GIEH or GIEL bits are set, the PC is loaded with the interrupt vector (008h or 0018h). DS39631E-page 48 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS Register Applicable Devices Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt TOSU 2420 2520 4420 4520 ---0 0000 ---0 0000 ---0 uuuu(3) TOSH 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu(3) TOSL 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu(3) STKPTR 2420 2520 4420 4520 00-0 0000 uu-0 0000 uu-u uuuu(3) PCLATU 2420 2520 4420 4520 ---0 0000 ---0 0000 ---u uuuu PCLATH 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu PCL 2420 2520 4420 4520 0000 0000 0000 0000 PC + 2(2) TBLPTRU 2420 2520 4420 4520 --00 0000 --00 0000 --uu uuuu TBLPTRH 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu TBLPTRL 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu TABLAT 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu PRODH 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu PRODL 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu INTCON 2420 2520 4420 4520 0000 000x 0000 000u uuuu uuuu(1) INTCON2 2420 2520 4420 4520 1111 -1-1 1111 -1-1 uuuu -u-u(1) INTCON3 2420 2520 4420 4520 11-0 0-00 11-0 0-00 uu-u u-uu(1) INDF0 2420 2520 4420 4520 N/A N/A N/A POSTINC0 2420 2520 4420 4520 N/A N/A N/A POSTDEC0 2420 2520 4420 4520 N/A N/A N/A PREINC0 2420 2520 4420 4520 N/A N/A N/A PLUSW0 2420 2520 4420 4520 N/A N/A N/A FSR0H 2420 2520 4420 4520 ---- 0000 ---- 0000 ---- uuuu FSR0L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu WREG 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu INDF1 2420 2520 4420 4520 N/A N/A N/A POSTINC1 2420 2520 4420 4520 N/A N/A N/A POSTDEC1 2420 2520 4420 4520 N/A N/A N/A PREINC1 2420 2520 4420 4520 N/A N/A N/A PLUSW1 2420 2520 4420 4520 N/A N/A N/A Legend: Note 1: 2: 3: 4: 5: 6: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. See Table 4-3 for Reset value for specific condition. Bits 6 and 7 of PORTA, LATA and TRISA are enabled depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'. The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111. (c) 2008 Microchip Technology Inc. DS39631E-page 49 PIC18F2420/2520/4420/4520 TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED) Register Power-on Reset, Brown-out Reset MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt 4520 ---- 0000 ---- 0000 ---- uuuu Applicable Devices FSR1H 2420 2520 4420 FSR1L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu BSR 2420 2520 4420 4520 ---- 0000 ---- 0000 ---- uuuu INDF2 2420 2520 4420 4520 N/A N/A N/A POSTINC2 2420 2520 4420 4520 N/A N/A N/A POSTDEC2 2420 2520 4420 4520 N/A N/A N/A PREINC2 2420 2520 4420 4520 N/A N/A N/A PLUSW2 2420 2520 4420 4520 N/A N/A N/A FSR2H 2420 2520 4420 4520 ---- 0000 ---- 0000 ---- uuuu FSR2L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu STATUS 2420 2520 4420 4520 ---x xxxx ---u uuuu ---u uuuu TMR0H 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu TMR0L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu T0CON 2420 2520 4420 4520 1111 1111 1111 1111 uuuu uuuu OSCCON 2420 2520 4420 4520 0100 q000 0100 q000 uuuu quuu HLVDCON 2420 2520 4420 4520 0-00 0101 0-00 0101 u-uu uuuu WDTCON 2420 2520 4420 4520 ---- ---0 ---- ---0 ---- ---u (4) 2420 2520 4420 4520 0q-1 11q0 0q-q qquu uq-u qquu TMR1H 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu TMR1L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu T1CON 2420 2520 4420 4520 0000 0000 u0uu uuuu uuuu uuuu TMR2 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu PR2 2420 2520 4420 4520 1111 1111 1111 1111 1111 1111 T2CON 2420 2520 4420 4520 -000 0000 -000 0000 -uuu uuuu SSPBUF 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu SSPADD 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu SSPSTAT 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu SSPCON1 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu SSPCON2 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu RCON Legend: Note 1: 2: 3: 4: 5: 6: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. See Table 4-3 for Reset value for specific condition. Bits 6 and 7 of PORTA, LATA and TRISA are enabled depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'. The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111. DS39631E-page 50 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED) Register ADRESH Power-on Reset, Brown-out Reset Applicable Devices 2420 2520 MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu uuuu uuuu ADRESL 2420 2520 4420 4520 xxxx xxxx uuuu uuuu ADCON0 2420 2520 4420 4520 --00 0000 --00 0000 --uu uuuu ADCON1 2420 2520 4420 4520 --00 0qqq(6) --00 0qqq(6) --uu uuuu ADCON2 2420 2520 4420 4520 0-00 0000 0-00 0000 u-uu uuuu CCPR1H 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu CCPR1L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu 2420 2520 4420 4520 --00 0000 --00 0000 --uu uuuu CCPR2H 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu CCPR2L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu CCP2CON 2420 2520 4420 4520 --00 0000 --00 0000 --uu uuuu BAUDCON 2420 2520 4420 4520 0100 0-00 0100 0-00 uuuu u-uu CCP1CON PWM1CON ECCP1AS CVRCON 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu 2420 2520 4420 4520 0000 00-- 0000 00-- uuuu uu-- 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu CMCON 2420 2520 4420 4520 0000 0111 0000 0111 uuuu uuuu TMR3H 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu TMR3L 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu T3CON 2420 2520 4420 4520 0000 0000 uuuu uuuu uuuu uuuu SPBRGH 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu SPBRG 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu RCREG 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu TXREG 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu TXSTA 2420 2520 4420 4520 0000 0010 0000 0010 uuuu uuuu RCSTA 2420 2520 4420 4520 0000 000x 0000 000x uuuu uuuu EEADR 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu EEDATA 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu EECON2 2420 2520 4420 4520 0000 0000 0000 0000 0000 0000 EECON1 2420 2520 4420 4520 xx-0 x000 uu-0 u000 uu-0 u000 Legend: Note 1: 2: 3: 4: 5: 6: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. See Table 4-3 for Reset value for specific condition. Bits 6 and 7 of PORTA, LATA and TRISA are enabled depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'. The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111. (c) 2008 Microchip Technology Inc. DS39631E-page 51 PIC18F2420/2520/4420/4520 TABLE 4-4: INITIALIZATION CONDITIONS FOR ALL REGISTERS (CONTINUED) Register Power-on Reset, Brown-out Reset Applicable Devices MCLR Resets, WDT Reset, RESET Instruction, Stack Resets Wake-up via WDT or Interrupt IPR2 2420 2520 4420 4520 11-1 1111 11-1 1111 uu-u uuuu PIR2 2420 2520 4420 4520 00-0 0000 00-0 0000 uu-u uuuu(1) PIE2 IPR1 PIR1 2420 2520 4420 4520 00-0 0000 00-0 0000 uu-u uuuu 2420 2520 4420 4520 1111 1111 1111 1111 uuuu uuuu 2420 2520 4420 4520 -111 1111 -111 1111 -uuu uuuu 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu(1) 2420 2520 4420 4520 -000 0000 -000 0000 -uuu uuuu(1) 2420 2520 4420 4520 0000 0000 0000 0000 uuuu uuuu 2420 2520 4420 4520 -000 0000 -000 0000 -uuu uuuu OSCTUNE 2420 2520 4420 4520 00-0 0000 00-0 0000 uu-u uuuu TRISE 2420 2520 4420 4520 0000 -111 0000 -111 uuuu -uuu PIE1 TRISD 2420 2520 4420 4520 1111 1111 1111 1111 uuuu uuuu TRISC 2420 2520 4420 4520 1111 1111 1111 1111 uuuu uuuu TRISB 2420 2520 4420 4520 1111 1111 1111 1111 uuuu uuuu TRISA(5) 2420 2520 4420 4520 1111 1111(5) 1111 1111(5) uuuu uuuu(5) LATE 2420 2520 4420 4520 ---- -xxx ---- -uuu ---- -uuu LATD 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu LATC 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu LATB 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu LATA(5) 2420 2520 4420 4520 xxxx xxxx(5) uuuu uuuu(5) uuuu uuuu(5) PORTE 2420 2520 4420 4520 ---- xxxx ---- uuuu ---- uuuu PORTD 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu PORTC 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu PORTB 2420 2520 4420 4520 xxxx xxxx uuuu uuuu uuuu uuuu PORTA(5) 2420 2520 4420 4520 xx0x 0000(5) uu0u 0000(5) uuuu uuuu(5) Legend: Note 1: 2: 3: 4: 5: 6: u = unchanged, x = unknown, - = unimplemented bit, read as `0', q = value depends on condition. Shaded cells indicate conditions do not apply for the designated device. One or more bits in the INTCONx or PIRx registers will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the PC is loaded with the interrupt vector (0008h or 0018h). When the wake-up is due to an interrupt and the GIEL or GIEH bit is set, the TOSU, TOSH and TOSL are updated with the current value of the PC. The STKPTR is modified to point to the next location in the hardware stack. See Table 4-3 for Reset value for specific condition. Bits 6 and 7 of PORTA, LATA and TRISA are enabled depending on the oscillator mode selected. When not enabled as PORTA pins, they are disabled and read `0'. The Reset value of the PCFG bits depends on the value of the PBADEN Configuration bit (CONFIG3H<1>). When PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111. DS39631E-page 52 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.0 MEMORY ORGANIZATION 5.1 PIC18 microcontrollers implement a 21-bit program counter, which is capable of addressing a 2-Mbyte program memory space. Accessing a location between the upper boundary of the physically implemented memory and the 2-Mbyte address will return all `0's (a NOP instruction). There are three types of memory in PIC18 enhanced microcontroller devices: * Program Memory * Data RAM * Data EEPROM As Harvard architecture devices, the data and program memories use separate busses; this allows for concurrent access of the two memory spaces. The data EEPROM, for practical purposes, can be regarded as a peripheral device, since it is addressed and accessed through a set of control registers. The PIC18F2420 and PIC18F4420 each have 16 Kbytes of Flash memory and can store up to 8,192 single-word instructions. The PIC18F2520 and PIC18F4520 each have 32 Kbytes of Flash memory and can store up to 16,384 single-word instructions. PIC18 devices have two interrupt vectors. The Reset vector address is at 0000h and the interrupt vector addresses are at 0008h and 0018h. Additional detailed information on the operation of the Flash program memory is provided in Section 6.0 "Flash Program Memory". Data EEPROM is discussed separately in Section 7.0 "Data EEPROM Memory". FIGURE 5-1: Program Memory Organization The program memory map for PIC18F2420/2520/ 4420/4520 devices is shown in Figure 5-1. PROGRAM MEMORY MAP AND STACK FOR PIC18F2420/2520/4420/4520 DEVICES PC<20:0> CALL,RCALL,RETURN RETFIE,RETLW Stack Level 1 21 * * * Stack Level 31 Reset Vector 0000h High-Priority Interrupt Vector 0008h Low-Priority Interrupt Vector 0018h On-Chip Program Memory On-Chip Program Memory User Memory Space 3FFFh 4000h PIC18F2420/4420 7FFFh 8000h PIC18F2520/4520 Read `0' Read `0' 1FFFFFh 200000h (c) 2008 Microchip Technology Inc. DS39631E-page 53 PIC18F2420/2520/4420/4520 5.1.1 PROGRAM COUNTER The Program Counter (PC) specifies the address of the instruction to fetch for execution. The PC is 21 bits wide and is contained in three separate 8-bit registers. The low byte, known as the PCL register, is both readable and writable. The high byte, or PCH register, contains the PC<15:8> bits; it is not directly readable or writable. Updates to the PCH register are performed through the PCLATH register. The upper byte is called PCU. This register contains the PC<20:16> bits; it is also not directly readable or writable. Updates to the PCU register are performed through the PCLATU register. The contents of PCLATH and PCLATU are transferred to the program counter by any operation that writes PCL. Similarly, the upper two bytes of the program counter are transferred to PCLATH and PCLATU by an operation that reads PCL. This is useful for computed offsets to the PC (see Section 5.1.4.1 "Computed GOTO"). The PC addresses bytes in the program memory. To prevent the PC from becoming misaligned with word instructions, the Least Significant bit of PCL is fixed to a value of `0'. The PC increments by 2 to address sequential instructions in the program memory. The CALL, RCALL, GOTO and program branch instructions write to the program counter directly. For these instructions, the contents of PCLATH and PCLATU are not transferred to the program counter. 5.1.2 RETURN ADDRESS STACK The return address stack allows any combination of up to 31 program calls and interrupts to occur. The PC is pushed onto the stack when a CALL or RCALL instruction is executed or an interrupt is Acknowledged. The PC value is pulled off the stack on a RETURN, RETLW or a RETFIE instruction. PCLATU and PCLATH are not affected by any of the RETURN or CALL instructions. FIGURE 5-2: The stack operates as a 31-word by 21-bit RAM and a 5-bit Stack Pointer, STKPTR. The stack space is not part of either program or data space. The Stack Pointer is readable and writable and the address on the top of the stack is readable and writable through the Top-ofStack (TOS) Special Function Registers. Data can also be pushed to, or popped from the stack, using these registers. A CALL type instruction causes a push onto the stack; the Stack Pointer is first incremented and the location pointed to by the Stack Pointer is written with the contents of the PC (already pointing to the instruction following the CALL). A RETURN type instruction causes a pop from the stack; the contents of the location pointed to by the STKPTR are transferred to the PC and then the Stack Pointer is decremented. The Stack Pointer is initialized to `00000' after all Resets. There is no RAM associated with the location corresponding to a Stack Pointer value of `00000'; this is only a Reset value. Status bits indicate if the stack is full, or has overflowed or underflowed. 5.1.2.1 Top-of-Stack Access Only the top of the return address stack (TOS) is readable and writable. A set of three registers, TOSU:TOSH:TOSL, hold the contents of the stack location pointed to by the STKPTR register (Figure 5-2). This allows users to implement a software stack if necessary. After a CALL, RCALL or interrupt, the software can read the pushed value by reading the TOSU:TOSH:TOSL registers. These values can be placed on a user-defined software stack. At return time, the software can return these values to TOSU:TOSH:TOSL and do a return. The user must disable the global interrupt enable bits while accessing the stack to prevent inadvertent stack corruption. RETURN ADDRESS STACK AND ASSOCIATED REGISTERS Return Address Stack <20:0> 11111 11110 11101 Top-of-Stack Registers TOSU 00h TOSH 1Ah DS39631E-page 54 STKPTR<4:0> 00010 TOSL 34h Top-of-Stack Stack Pointer 001A34h 000D58h 00011 00010 00001 00000 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.1.2.2 Return Stack Pointer (STKPTR) The STKPTR register (Register 5-1) contains the Stack Pointer value, the STKFUL (Stack Full) status bit and the STKUNF (Stack Underflow) status bits. The value of the Stack Pointer can be 0 through 31. The Stack Pointer increments before values are pushed onto the stack and decrements after values are popped off the stack. On Reset, the Stack Pointer value will be zero. The user may read and write the Stack Pointer value. This feature can be used by a Real-Time Operating System (RTOS) for return stack maintenance. After the PC is pushed onto the stack 31 times (without popping any values off the stack), the STKFUL bit is set. The STKFUL bit is cleared by software or by a POR. The action that takes place when the stack becomes full depends on the state of the STVREN (Stack Overflow Reset Enable) Configuration bit. (Refer to Section 23.1 "Configuration Bits" for a description of the device Configuration bits.) If STVREN is set (default), the 31st push will push the (PC + 2) value onto the stack, set the STKFUL bit and reset the device. The STKFUL bit will remain set and the Stack Pointer will be set to zero. If STVREN is cleared, the STKFUL bit will be set on the 31st push and the Stack Pointer will increment to 31. Any additional pushes will not overwrite the 31st push and STKPTR will remain at 31. REGISTER 5-1: When the stack has been popped enough times to unload the stack, the next pop will return a value of zero to the PC and sets the STKUNF bit, while the Stack Pointer remains at zero. The STKUNF bit will remain set until cleared by software or until a POR occurs. Note: 5.1.2.3 Returning a value of zero to the PC on an underflow has the effect of vectoring the program to the Reset vector, where the stack conditions can be verified and appropriate actions can be taken. This is not the same as a Reset, as the contents of the SFRs are not affected. PUSH and POP Instructions Since the Top-of-Stack is readable and writable, the ability to push values onto the stack and pull values off the stack without disturbing normal program execution is a desirable feature. The PIC18 instruction set includes two instructions, PUSH and POP, that permit the TOS to be manipulated under software control. TOSU, TOSH and TOSL can be modified to place data or a return address on the stack. The PUSH instruction places the current PC value onto the stack. This increments the Stack Pointer and loads the current PC value onto the stack. The POP instruction discards the current TOS by decrementing the Stack Pointer. The previous value pushed onto the stack then becomes the TOS value. STKPTR: STACK POINTER REGISTER R/C-0 R/C-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 STKFUL(1) STKUNF(1) -- SP4 SP3 SP2 SP1 SP0 bit 7 bit 0 Legend: C = Clearable bit R = Readable bit W = Writable bit U = Unimplemented bit, read as `0' -n = Value at POR `1' = Bit is set `0' = Bit is cleared bit 7 STKFUL: Stack Full Flag bit(1) 1 = Stack became full or overflowed 0 = Stack has not become full or overflowed bit 6 STKUNF: Stack Underflow Flag bit(1) 1 = Stack underflow occurred 0 = Stack underflow did not occur bit 5 Unimplemented: Read as `0' bit 4-0 SP<4:0>: Stack Pointer Location bits Note 1: x = Bit is unknown Bit 7 and bit 6 are cleared by user software or by a POR. (c) 2008 Microchip Technology Inc. DS39631E-page 55 PIC18F2420/2520/4420/4520 5.1.2.4 Stack Full and Underflow Resets Device Resets on stack overflow and stack underflow conditions are enabled by setting the STVREN bit in Configuration Register 4L. When STVREN is set, a full or underflow will set the appropriate STKFUL or STKUNF bit and then cause a device Reset. When STVREN is cleared, a full or underflow condition will set the appropriate STKFUL or STKUNF bit but not cause a device Reset. The STKFUL or STKUNF bits are cleared by the user software or a Power-on Reset. 5.1.3 FAST REGISTER STACK A Fast Register Stack is provided for the STATUS, WREG and BSR registers, to provide a "fast return" option for interrupts. The stack for each register is only one level deep and is neither readable nor writable. It is loaded with the current value of the corresponding register when the processor vectors for an interrupt. All interrupt sources will push values into the stack registers. The values in the registers are then loaded back into their associated registers if the RETFIE, FAST instruction is used to return from the interrupt. 5.1.4 LOOK-UP TABLES IN PROGRAM MEMORY There may be programming situations that require the creation of data structures, or look-up tables, in program memory. For PIC18 devices, look-up tables can be implemented in two ways: * Computed GOTO * Table Reads 5.1.4.1 Computed GOTO A computed GOTO is accomplished by adding an offset to the program counter. An example is shown in Example 5-2. A look-up table can be formed with an ADDWF PCL instruction and a group of RETLW nn instructions. The W register is loaded with an offset into the table before executing a call to that table. The first instruction of the called routine is the ADDWF PCL instruction. The next instruction executed will be one of the RETLW nn instructions that returns the value `nn' to the calling function. If both low and high-priority interrupts are enabled, the stack registers cannot be used reliably to return from low-priority interrupts. If a high-priority interrupt occurs while servicing a low-priority interrupt, the stack register values stored by the low-priority interrupt will be overwritten. In these cases, users must save the key registers in software during a low-priority interrupt. The offset value (in WREG) specifies the number of bytes that the program counter should advance and should be multiples of 2 (LSb = 0). If interrupt priority is not used, all interrupts may use the Fast Register Stack for returns from interrupt. If no interrupts are used, the Fast Register Stack can be used to restore the STATUS, WREG and BSR registers at the end of a subroutine call. To use the Fast Register Stack for a subroutine call, a CALL label, FAST instruction must be executed to save the STATUS, WREG and BSR registers to the Fast Register Stack. A RETURN, FAST instruction is then executed to restore these registers from the Fast Register Stack. EXAMPLE 5-2: Example 5-1 shows a source code example that uses the Fast Register Stack during a subroutine call and return. EXAMPLE 5-1: CALL SUB1, FAST FAST REGISTER STACK CODE EXAMPLE ;STATUS, WREG, BSR ;SAVED IN FAST REGISTER ;STACK * * * * RETURN, FAST SUB1 DS39631E-page 56 ;RESTORE VALUES SAVED ;IN FAST REGISTER STACK In this method, only one data byte may be stored in each instruction location and room on the return address stack is required. ORG TABLE 5.1.4.2 MOVF CALL nn00h ADDWF RETLW RETLW RETLW . . . COMPUTED GOTO USING AN OFFSET VALUE OFFSET, W TABLE PCL nnh nnh nnh Table Reads and Table Writes A better method of storing data in program memory allows two bytes of data to be stored in each instruction location. Look-up table data may be stored two bytes per program word by using table reads and writes. The Table Pointer (TBLPTR) register specifies the byte address and the Table Latch (TABLAT) register contains the data that is read from or written to program memory. Data is transferred to or from program memory one byte at a time. Table read and table write operations are discussed further in Section 6.1 "Table Reads and Table Writes". (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.2 5.2.2 PIC18 Instruction Cycle 5.2.1 An "Instruction Cycle" consists of four Q cycles: Q1 through Q4. The instruction fetch and execute are pipelined in such a manner that a fetch takes one instruction cycle, while the decode and execute take another instruction cycle. However, due to the pipelining, each instruction effectively executes in one cycle. If an instruction causes the program counter to change (e.g., GOTO), then two cycles are required to complete the instruction (Example 5-3). CLOCKING SCHEME The microcontroller clock input, whether from an internal or external source, is internally divided by four to generate four non-overlapping quadrature clocks (Q1, Q2, Q3 and Q4). Internally, the program counter is incremented on every Q1; the instruction is fetched from the program memory and latched into the instruction register during Q4. The instruction is decoded and executed during the following Q1 through Q4. The clocks and instruction execution flow are shown in Figure 5-3. FIGURE 5-3: INSTRUCTION FLOW/PIPELINING A fetch cycle begins with the Program Counter (PC) incrementing in Q1. In the execution cycle, the fetched instruction is latched into the Instruction Register (IR) in cycle Q1. This instruction is then decoded and executed during the Q2, Q3 and Q4 cycles. Data memory is read during Q2 (operand read) and written during Q4 (destination write). CLOCK/INSTRUCTION CYCLE Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 OSC1 Q1 Q2 Internal Phase Clock Q3 Q4 PC PC PC + 2 PC + 4 OSC2/CLKO (RC mode) Execute INST (PC - 2) Fetch INST (PC) EXAMPLE 5-3: TCY0 TCY1 Fetch 1 Execute 1 2. MOVWF PORTB 4. BSF Execute INST (PC + 2) Fetch INST (PC + 4) INSTRUCTION PIPELINE FLOW 1. MOVLW 55h 3. BRA Execute INST (PC) Fetch INST (PC + 2) SUB_1 PORTA, BIT3 (Forced NOP) 5. Instruction @ address SUB_1 Fetch 2 TCY2 TCY3 TCY4 TCY5 Execute 2 Fetch 3 Execute 3 Fetch 4 Flush (NOP) Fetch SUB_1 Execute SUB_1 All instructions are single cycle, except for any program branches. These take two cycles since the fetch instruction is "flushed" from the pipeline while the new instruction is being fetched and then executed. (c) 2008 Microchip Technology Inc. DS39631E-page 57 PIC18F2420/2520/4420/4520 5.2.3 INSTRUCTIONS IN PROGRAM MEMORY The program memory is addressed in bytes. Instructions are stored as two bytes or four bytes in program memory. The Least Significant Byte of an instruction word is always stored in a program memory location with an even address (LSb = 0). To maintain alignment with instruction boundaries, the PC increments in steps of 2 and the LSb will always read `0' (see Section 5.1.1 "Program Counter"). Figure 5-4 shows an example of how instruction words are stored in the program memory. FIGURE 5-4: The CALL and GOTO instructions have the absolute program memory address embedded into the instruction. Since instructions are always stored on word boundaries, the data contained in the instruction is a word address. The word address is written to PC<20:1>, which accesses the desired byte address in program memory. Instruction #2 in Figure 5-4 shows how the instruction GOTO 0006h is encoded in the program memory. Program branch instructions, which encode a relative address offset, operate in the same manner. The offset value stored in a branch instruction represents the number of single-word instructions that the PC will be offset by. Section 24.0 "Instruction Set Summary" provides further details of the instruction set. INSTRUCTIONS IN PROGRAM MEMORY LSB = 1 LSB = 0 0Fh EFh F0h C1h F4h 55h 03h 00h 23h 56h Program Memory Byte Locations 5.2.4 Instruction 1: Instruction 2: MOVLW GOTO 055h 0006h Instruction 3: MOVFF 123h, 456h TWO-WORD INSTRUCTIONS The standard PIC18 instruction set has four two-word instructions: CALL, MOVFF, GOTO and LSFR. In all cases, the second word of the instructions always has `1111' as its four Most Significant bits; the other 12 bits are literal data, usually a data memory address. The use of `1111' in the 4 MSbs of an instruction specifies a special form of NOP. If the instruction is executed in proper sequence - immediately after the first word - the data in the second word is accessed and used by EXAMPLE 5-4: Word Address 000000h 000002h 000004h 000006h 000008h 00000Ah 00000Ch 00000Eh 000010h 000012h 000014h the instruction sequence. If the first word is skipped for some reason and the second word is executed by itself, a NOP is executed instead. This is necessary for cases when the two-word instruction is preceded by a conditional instruction that changes the PC. Example 5-4 shows how this works. Note: See Section 5.6 "PIC18 Instruction Execution and the Extended Instruction Set" for information on two-word instructions in the extended instruction set. TWO-WORD INSTRUCTIONS CASE 1: Object Code 0110 0110 0000 1100 0001 0010 1111 0100 0101 0010 0100 0000 0000 0011 0110 0000 Source Code TSTFSZ REG1 ; is RAM location 0? MOVFF REG1, REG2 ; No, skip this word ; Execute this word as a NOP ADDWF REG3 ; continue code 0000 0011 0110 0000 Source Code TSTFSZ REG1 ; is RAM location 0? MOVFF REG1, REG2 ; Yes, execute this word ; 2nd word of instruction ADDWF REG3 ; continue code CASE 2: Object Code 0110 0110 0000 1100 0001 0010 1111 0100 0101 0010 0100 0000 DS39631E-page 58 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.3 Note: Data Memory Organization The operation of some aspects of data memory are changed when the PIC18 extended instruction set is enabled. See Section 5.5 "Data Memory and the Extended Instruction Set" for more information. The data memory in PIC18 devices is implemented as static RAM. Each register in the data memory has a 12-bit address, allowing up to 4096 bytes of data memory. The memory space is divided into as many as 16 banks that contain 256 bytes each; PIC18F2420/ 2520/4420/4520 devices implement all 16 banks. Figure 5-5 shows the data memory organization for the PIC18F2420/2520/4420/4520 devices. The data memory contains Special Function Registers (SFRs) and General Purpose Registers (GPRs). The SFRs are used for control and status of the controller and peripheral functions, while GPRs are used for data storage and scratchpad operations in the user's application. Any read of an unimplemented location will read as `0's. The instruction set and architecture allow operations across all banks. The entire data memory may be accessed by Direct, Indirect or Indexed Addressing modes. Addressing modes are discussed later in this subsection. To ensure that commonly used registers (SFRs and select GPRs) can be accessed in a single cycle, PIC18 devices implement an Access Bank. This is a 256-byte memory space that provides fast access to SFRs and the lower portion of GPR Bank 0 without using the BSR. Section 5.3.2 "Access Bank" provides a detailed description of the Access RAM. 5.3.1 BANK SELECT REGISTER (BSR) Large areas of data memory require an efficient addressing scheme to make rapid access to any address possible. Ideally, this means that an entire address does not need to be provided for each read or write operation. For PIC18 devices, this is accomplished with a RAM banking scheme. This divides the memory space into 16 contiguous banks of 256 bytes. Depending on the instruction, each location can be addressed directly by its full 12-bit address, or an 8-bit low-order address and a 4-bit Bank Pointer. Most instructions in the PIC18 instruction set make use of the Bank Pointer, known as the Bank Select Register (BSR). This SFR holds the 4 Most Significant bits of a location's address; the instruction itself includes the 8 Least Significant bits. Only the four lower bits of the BSR are implemented (BSR<3:0>). The upper four bits are unused; they will always read `0' and cannot be written to. The BSR can be loaded directly by using the MOVLB instruction. The value of the BSR indicates the bank in data memory; the 8 bits in the instruction show the location in the bank and can be thought of as an offset from the bank's lower boundary. The relationship between the BSR's value and the bank division in data memory is shown in Figure 5-7. Since up to 16 registers may share the same low-order address, the user must always be careful to ensure that the proper bank is selected before performing a data read or write. For example, writing what should be program data to an 8-bit address of F9h while the BSR is 0Fh will end up resetting the program counter. While any bank can be selected, only those banks that are actually implemented can be read or written to. Writes to unimplemented banks are ignored, while reads from unimplemented banks will return `0's. Even so, the STATUS register will still be affected as if the operation was successful. The data memory map in Figure 5-5 indicates which banks are implemented. In the core PIC18 instruction set, only the MOVFF instruction fully specifies the 12-bit address of the source and target registers. This instruction ignores the BSR completely when it executes. All other instructions include only the low-order address as an operand and must use either the BSR or the Access Bank to locate their target registers. (c) 2008 Microchip Technology Inc. DS39631E-page 59 PIC18F2420/2520/4420/4520 FIGURE 5-5: DATA MEMORY MAP FOR PIC18F2420/4420 DEVICES BSR<3:0> = 0000 = 0001 = 0010 = 0011 = 0100 = 0101 = 0110 = 0111 = 1000 = 1001 = 1010 = 1011 = 1100 = 1101 = 1110 = 1111 DS39631E-page 60 When `a' = 0: Data Memory Map 00h Access RAM FFh 00h GPR Bank 0 GPR Bank 1 Bank 2 Bank 3 Bank 4 Bank 5 Bank 6 Bank 7 Bank 8 Bank 9 000h 07Fh 080h 0FFh 100h 1FFh 200h FFh 00h 2FFh 300h FFh 00h 3FFh 400h FFh 00h 4FFh 500h FFh 00h 5FFh 600h FFh 00h 6FFh 700h 7FFh 800h FFh 00h FFh 00h Unused Read 00h FFh 00h AFFh B00h FFh 00h BFFh C00h FFh Bank 13 00h CFFh D00h FFh 00h DFFh E00h Bank 12 Bank 14 The second 128 bytes are Special Function Registers (from Bank 15). FFh 00h Unused FFh SFR Bank 15 When `a' = 1: The BSR specifies the Bank used by the instruction. Access Bank Access RAM Low 00h 7Fh Access RAM High 80h (SFRs) FFh 8FFh 900h 9FFh A00h Bank 11 The first 128 bytes are general purpose RAM (from Bank 0). GPR FFh 00h FFh 00h Bank 10 The BSR is ignored and the Access Bank is used. EFFh F00h F7Fh F80h FFFh (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 5-6: DATA MEMORY MAP FOR PIC18F2520/4520 DEVICES BSR<3:0> = 0000 = 0001 = 0010 = 0011 = 0100 = 0101 = 0110 = 0111 = 1000 = 1001 = 1010 = 1011 = 1100 = 1101 = 1110 = 1111 When `a' = 0: Data Memory Map 00h Access RAM FFh 00h GPR Bank 0 GPR Bank 1 Bank 2 Bank 3 Bank 4 Bank 5 Bank 6 Bank 7 Bank 8 Bank 9 Bank 10 000h 07Fh 080h 0FFh 100h 1FFh 200h FFh 00h 2FFh 300h GPR 3FFh 400h FFh 00h The BSR specifies the Bank used by the instruction. GPR FFh 00h 5FFh 600h FFh 00h 6FFh 700h FFh 00h 7FFh 800h FFh 00h 8FFh 900h FFh 00h Unused Read 00h FFh Bank 13 00h CFFh D00h FFh 00h DFFh E00h FFh 00h Unused FFh SFR Bank 15 Access Bank Access RAM Low 00h 7Fh Access RAM High 80h (SFRs) FFh 9FFh A00h BFFh C00h (c) 2008 Microchip Technology Inc. When `a' = 1: 4FFh 500h FFh 00h FFh 00h Bank 14 The second 128 bytes are Special Function Registers (from Bank 15). GPR AFFh B00h Bank 12 The first 128 bytes are general purpose RAM (from Bank 0). GPR FFh 00h FFh 00h Bank 11 The BSR is ignored and the Access Bank is used. EFFh F00h F7Fh F80h FFFh DS39631E-page 61 PIC18F2420/2520/4420/4520 FIGURE 5-7: USE OF THE BANK SELECT REGISTER (DIRECT ADDRESSING) BSR(1) 7 0 0 0 0 0 0 0 Bank Select(2) 1 1 000h Data Memory Bank 0 100h Bank 1 200h 300h Bank 2 00h 7 FFh 00h 1 From Opcode(2) 1 1 1 1 1 0 1 1 FFh 00h FFh 00h Bank 3 through Bank 13 E00h Bank 14 F00h FFFh Note 1: 2: 5.3.2 Bank 15 FFh 00h FFh 00h FFh The Access RAM bit of the instruction can be used to force an override of the selected bank (BSR<3:0>) to the registers of the Access Bank. The MOVFF instruction embeds the entire 12-bit address in the instruction. ACCESS BANK While the use of the BSR with an embedded 8-bit address allows users to address the entire range of data memory, it also means that the user must always ensure that the correct bank is selected. Otherwise, data may be read from or written to the wrong location. This can be disastrous if a GPR is the intended target of an operation, but an SFR is written to instead. Verifying and/or changing the BSR for each read or write to data memory can become very inefficient. To streamline access for the most commonly used data memory locations, the data memory is configured with an Access Bank, which allows users to access a mapped block of memory without specifying a BSR. The Access Bank consists of the first 128 bytes of memory (00h-7Fh) in Bank 0 and the last 128 bytes of memory (80h-FFh) in Block 15. The lower half is known as the "Access RAM" and is composed of GPRs. This upper half is also where the device's SFRs are mapped. These two areas are mapped contiguously in the Access Bank and can be addressed in a linear fashion by an 8-bit address (Figure 5-5). The Access Bank is used by core PIC18 instructions that include the Access RAM bit (the `a' parameter in the instruction). When `a' is equal to `1', the instruction uses the BSR and the 8-bit address included in the opcode for the data memory address. When `a' is `0', DS39631E-page 62 however, the instruction is forced to use the Access Bank address map; the current value of the BSR is ignored entirely. Using this "forced" addressing allows the instruction to operate on a data address in a single cycle, without updating the BSR first. For 8-bit addresses of 80h and above, this means that users can evaluate and operate on SFRs more efficiently. The Access RAM below 80h is a good place for data values that the user might need to access rapidly, such as immediate computational results or common program variables. Access RAM also allows for faster and more code efficient context saving and switching of variables. The mapping of the Access Bank is slightly different when the extended instruction set is enabled (XINST Configuration bit = 1). This is discussed in more detail in Section 5.5.3 "Mapping the Access Bank in Indexed Literal Offset Mode". 5.3.3 GENERAL PURPOSE REGISTER FILE PIC18 devices may have banked memory in the GPR area. This is data RAM, which is available for use by all instructions. GPRs start at the bottom of Bank 0 (address 000h) and grow upwards towards the bottom of the SFR area. GPRs are not initialized by a Power-on Reset and are unchanged on all other Resets. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.3.4 SPECIAL FUNCTION REGISTERS The Special Function Registers (SFRs) are registers used by the CPU and peripheral modules for controlling the desired operation of the device. These registers are implemented as static RAM. SFRs start at the top of data memory (FFFh) and extend downward to occupy the top half of Bank 15 (F80h to FFFh). A list of these registers is given in Table 5-1 and Table 5-2. TABLE 5-1: Address The SFRs can be classified into two sets: those associated with the "core" device functionality (ALU, Resets and interrupts) and those related to the peripheral functions. The Reset and Interrupt registers are described in their respective chapters, while the ALU's STATUS register is described later in this section. Registers related to the operation of a peripheral feature are described in the chapter for that peripheral. The SFRs are typically distributed among the peripherals whose functions they control. Unused SFR locations are unimplemented and read as `0's. SPECIAL FUNCTION REGISTER MAP FOR PIC18F2420/2520/4420/4520 DEVICES Name Address Name INDF2(1) Address Name Address Name FFFh TOSU FDFh FBFh CCPR1H F9Fh IPR1 FFEh TOSH FDEh POSTINC2(1) FBEh CCPR1L F9Eh PIR1 FFDh TOSL FDDh POSTDEC2(1) FBDh CCP1CON F9Dh PIE1 FFCh STKPTR FDCh PREINC2(1) FBCh CCPR2H F9Ch --(2) FFBh PCLATU FDBh PLUSW2(1) FBBh CCPR2L F9Bh OSCTUNE FFAh PCLATH FDAh FSR2H FBAh CCP2CON F9Ah --(2) FF9h PCL FD9h FSR2L FB9h --(2) F99h --(2) FF8h TBLPTRU FD8h STATUS FB8h BAUDCON F98h --(2) FF7h TBLPTRH FD7h TMR0H FB7h PWM1CON(3) F97h --(2) F96h TRISE(3) FF6h TBLPTRL FD6h TMR0L FB6h ECCP1AS(3) FF5h TABLAT FD5h T0CON FB5h CVRCON F95h TRISD(3) FD4h --(2) FB4h CMCON F94h TRISC FF4h PRODH FF3h PRODL FD3h OSCCON FB3h TMR3H F93h TRISB FF2h INTCON FD2h HLVDCON FB2h TMR3L F92h TRISA FF1h INTCON2 FD1h WDTCON FB1h T3CON F91h --(2) FF0h INTCON3 FD0h RCON FB0h SPBRGH F90h --(2) FEFh INDF0(1) FCFh TMR1H FAFh SPBRG F8Fh --(2) FEEh POSTINC0(1) FCEh TMR1L FAEh RCREG F8Eh --(2) FEDh POSTDEC0(1) FCDh T1CON FADh TXREG F8Dh LATE(3) FCCh TMR2 FACh TXSTA F8Ch LATD(3) FECh PREINC0(1) FEBh PLUSW0(1) FCBh PR2 FABh RCSTA F8Bh LATC FEAh FSR0H FCAh T2CON FAAh --(2) F8Ah LATB FE9h FSR0L FC9h SSPBUF FA9h EEADR F89h LATA FE8h WREG FC8h SSPADD FA8h EEDATA F88h --(2) FE7h INDF1(1) FC7h SSPSTAT FA7h EECON2(1) F87h --(2) FE6h POSTINC1(1) FC6h SSPCON1 FA6h EECON1 F86h --(2) FE5h POSTDEC1(1) FC5h SSPCON2 FA5h --(2) F85h --(2) F84h PORTE(3) FE4h PREINC1(1) FC4h ADRESH FA4h --(2) FE3h PLUSW1(1) FC3h ADRESL FA3h --(2) F83h PORTD(3) FE2h FSR1H FC2h ADCON0 FA2h IPR2 F82h PORTC FE1h FSR1L FC1h ADCON1 FA1h PIR2 F81h PORTB FE0h BSR FC0h ADCON2 FA0h PIE2 F80h PORTA Note 1: 2: 3: This is not a physical register. Unimplemented registers are read as `0'. This register is not available on 28-pin devices. (c) 2008 Microchip Technology Inc. DS39631E-page 63 PIC18F2420/2520/4420/4520 TABLE 5-2: File Name PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY Bit 7 Bit 6 Bit 5 -- -- -- Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Details on page: ---0 0000 49, 54 TOSH Top-of-Stack High Byte (TOS<15:8>) 0000 0000 49, 54 TOSL Top-of-Stack Low Byte (TOS<7:0>) 0000 0000 49, 54 00-0 0000 49, 55 ---0 0000 49, 54 TOSU STKPTR STKFUL STKUNF -- PCLATU -- -- -- Top-of-Stack Upper Byte (TOS<20:16>) Value on POR, BOR SP4 SP3 SP2 SP1 SP0 Holding Register for PC<20:16> PCLATH Holding Register for PC<15:8> 0000 0000 49, 54 PCL PC Low Byte (PC<7:0>) 0000 0000 49, 54 --00 0000 49, 76 TBLPTRU -- -- bit 21 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) TBLPTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) 0000 0000 49, 76 TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>) 0000 0000 49, 76 TABLAT Program Memory Table Latch 0000 0000 49, 76 PRODH Product Register High Byte xxxx xxxx 49, 89 PRODL Product Register Low Byte xxxx xxxx 49, 89 INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 0000 000x 49, 93 INTCON2 RBPU INTEDG0 INTEDG1 INTEDG2 -- TMR0IP -- RBIP 1111 -1-1 49, 94 INT2IP INT1IP -- INT2IE INT1IE -- INT2IF INT1IF 11-0 0-00 49, 95 N/A 49, 69 INTCON3 INDF0 Uses contents of FSR0 to address data memory - value of FSR0 not changed (not a physical register) POSTINC0 Uses contents of FSR0 to address data memory - value of FSR0 post-incremented (not a physical register) N/A 49, 69 POSTDEC0 Uses contents of FSR0 to address data memory - value of FSR0 post-decremented (not a physical register) N/A 49, 69 PREINC0 Uses contents of FSR0 to address data memory - value of FSR0 pre-incremented (not a physical register) N/A 49, 69 PLUSW0 Uses contents of FSR0 to address data memory - value of FSR0 pre-incremented (not a physical register) - value of FSR0 offset by W N/A 49, 69 FSR0H ---- 0000 49, 69 FSR0L Indirect Data Memory Address Pointer 0 Low Byte -- -- -- -- Indirect Data Memory Address Pointer 0 High Byte xxxx xxxx 49, 69 WREG Working Register xxxx xxxx 49 INDF1 Uses contents of FSR1 to address data memory - value of FSR1 not changed (not a physical register) N/A 49, 69 POSTINC1 Uses contents of FSR1 to address data memory - value of FSR1 post-incremented (not a physical register) N/A 49, 69 POSTDEC1 Uses contents of FSR1 to address data memory - value of FSR1 post-decremented (not a physical register) N/A 49, 69 PREINC1 Uses contents of FSR1 to address data memory - value of FSR1 pre-incremented (not a physical register) N/A 49, 69 PLUSW1 Uses contents of FSR1 to address data memory - value of FSR1 pre-incremented (not a physical register) - value of FSR1 offset by W N/A 49, 69 ---- 0000 50, 69 xxxx xxxx 50, 69 FSR1H -- FSR1L -- -- -- Indirect Data Memory Address Pointer 1 High Byte Indirect Data Memory Address Pointer 1 Low Byte BSR -- INDF2 -- -- -- Bank Select Register Uses contents of FSR2 to address data memory - value of FSR2 not changed (not a physical register) ---- 0000 50, 59 N/A 50, 69 POSTINC2 Uses contents of FSR2 to address data memory - value of FSR2 post-incremented (not a physical register) N/A 50, 69 POSTDEC2 Uses contents of FSR2 to address data memory - value of FSR2 post-decremented (not a physical register) N/A 50, 69 PREINC2 Uses contents of FSR2 to address data memory - value of FSR2 pre-incremented (not a physical register) N/A 50, 69 PLUSW2 Uses contents of FSR2 to address data memory - value of FSR2 pre-incremented (not a physical register) - value of FSR2 offset by W N/A 50, 69 ---- 0000 50, 69 FSR2H -- FSR2L -- -- -- Indirect Data Memory Address Pointer 2 High Byte Indirect Data Memory Address Pointer 2 Low Byte STATUS Legend: Note 1: 2: 3: 4: 5: -- -- -- N OV Z DC C xxxx xxxx 50, 69 ---x xxxx 50, 67 x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as `0'. The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 4.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 2.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. DS39631E-page 64 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 5-2: File Name PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY (CONTINUED) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Details on page: TMR0H Timer0 Register High Byte 0000 0000 50, 125 TMR0L Timer0 Register Low Byte xxxx xxxx 50, 125 50, 123 T0CON TMR0ON T08BIT T0CS T0SE PSA T0PS2 T0PS1 T0PS0 1111 1111 OSCCON IDLEN IRCF2 IRCF1 IRCF0 OSTS IOFS SCS1 SCS0 0100 q000 30, 50 HLVDCON VDIRMAG -- IRVST HLVDEN HLVDL3 HLVDL2 HLVDL1 HLVDL0 0-00 0101 50, 245 WDTCON -- -- -- -- -- -- -- SWDTEN --- ---0 50, 259 -- RI TO PD POR BOR 0q-1 11q0 42, 48, 102 RCON IPEN SBOREN (1) TMR1H Timer1 Register High Byte xxxx xxxx 50, 132 TMR1L Timer1 Register Low Bytes xxxx xxxx 50, 132 0000 0000 50, 127 50, 134 T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON TMR2 Timer2 Register 0000 0000 PR2 Timer2 Period Register 1111 1111 50, 134 -000 0000 50, 133 xxxx xxxx 50, 169, 170 T2CON -- T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 SSPBUF MSSP Receive Buffer/Transmit Register SSPADD MSSP Address Register in I2CTM Slave Mode. MSSP Baud Rate Reload Register in I2C Master Mode. 0000 0000 50, 170 SSPSTAT SMP CKE D/A P S R/W UA BF 0000 0000 50, 162, 171 SSPCON1 WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 0000 0000 50, 163, 172 GCEN ACKSTAT ACKDT ACKEN RCEN PEN RSEN SEN SSPCON2 0000 0000 50, 173 ADRESH A/D Result Register High Byte xxxx xxxx 51, 232 ADRESL A/D Result Register Low Byte xxxx xxxx 51, 232 ADCON0 -- -- CHS3 CHS2 CHS1 CHS0 GO/DONE ADON --00 0000 51, 223 ADCON1 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 --00 0qqq 51, 224 ADFM -- ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0 ADCON2 0-00 0000 51, 225 CCPR1H Capture/Compare/PWM Register 1 High Byte xxxx xxxx 51, 140 CCPR1L Capture/Compare/PWM Register 1 Low Byte xxxx xxxx 51, 140 0000 0000 51, 139, 147 51, 140 CCP1CON P1M1(2) P1M0(2) DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 CCPR2H Capture/Compare/PWM Register 2 High Byte xxxx xxxx CCPR2L Capture/Compare/PWM Register 2 Low Byte xxxx xxxx 51, 140 --00 0000 51, 139 CCP2CON -- BAUDCON ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 0100 0-00 51, 204 PWM1CON PRSEN PDC6(2) PDC5(2) PDC4(2) PDC3(2) PDC2(2) PDC1(2) PDC0(2) 0000 0000 51, 156 ECCP1AS ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(2) PSSBD0(2) 0000 0000 51, 157 CVRCON CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 0000 0000 51, 239 CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 0000 0111 51, 233 -- DC2B1 DC2B0 CCP2M3 CCP2M2 CCP2M1 CCP2M0 TMR3H Timer3 Register High Byte xxxx xxxx 51, 137 TMR3L Timer3 Register Low Byte xxxx xxxx 51, 137 0000 0000 51, 135 T3CON RD16 Legend: Note 1: 2: 3: 4: 5: T3CCP2 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as `0'. The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 4.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 2.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. (c) 2008 Microchip Technology Inc. DS39631E-page 65 PIC18F2420/2520/4420/4520 TABLE 5-2: File Name PIC18F2420/2520/4420/4520 REGISTER FILE SUMMARY (CONTINUED) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on POR, BOR Details on page: SPBRGH EUSART Baud Rate Generator Register High Byte 0000 0000 51, 206 SPBRG EUSART Baud Rate Generator Register Low Byte 0000 0000 51, 206 RCREG EUSART Receive Register 0000 0000 51, 213 TXREG EUSART Transmit Register 0000 0000 51, 211 TXSTA RCSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 0000 0010 51, 202 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 0000 000x 51, 203 EEADR EEPROM Address Register 0000 0000 51, 74, 83 EEDATA EEPROM Data Register 0000 0000 51, 74, 83 EECON2 EEPROM Control Register 2 (not a physical register) 0000 0000 51, 74, 83 EECON1 EEPGD CFGS -- FREE WRERR WREN WR RD xx-0 x000 51, 75, 84 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 11-1 1111 52, 101 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 00-0 0000 52, 97 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 00-0 0000 52, 99 IPR1 PSPIP(2) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 1111 1111 52, 100 52, 96 PIR1 PSPIF(2) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 PIE1 PSPIE(2) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 52, 98 OSCTUNE INTSRC PLLEN(3) -- TUN4 TUN3 TUN2 TUN1 TUN0 0q-0 0000 27, 52 IBF OBF IBOV PSPMODE -- TRISE2 TRISE1 TRISE0 TRISE(2) 0000 -111 52, 118 PORTD Data Direction Register 1111 1111 52, 114 TRISC PORTC Data Direction Register 1111 1111 52, 111 TRISB PORTB Data Direction Register 1111 1111 52, 108 1111 1111 52, 105 ---- -xxx 52, 117 52, 114 TRISD(2) TRISA TRISA7(5) TRISA6(5) LATE(2) -- -- PORTA Data Direction Register -- -- -- PORTE Data Latch Register (Read and Write to Data Latch) LATD(2) PORTD Data Latch Register (Read and Write to Data Latch) xxxx xxxx LATC PORTC Data Latch Register (Read and Write to Data Latch) xxxx xxxx 52, 111 LATB PORTB Data Latch Register (Read and Write to Data Latch) xxxx xxxx 52, 108 xxxx xxxx 52, 105 LATA7(5) LATA6(5) -- -- -- -- RE3(4) RE2(2) RE1(2) RE0(2) ---- xxxx 52, 117 PORTD(2) RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 xxxx xxxx 52, 114 PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx 52, 111 PORTB RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 xxxx xxxx 52, 108 RA7(5) RA6(5) RA5 RA4 RA3 RA2 RA1 RA0 xx0x 0000 52, 105 LATA PORTE PORTA Legend: Note 1: 2: 3: 4: 5: PORTA Data Latch Register (Read and Write to Data Latch) x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as `0'. The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 4.4 "Brown-out Reset (BOR)". These registers and/or bits are not implemented on 28-pin devices and are read as `0'. Reset values are shown for 40/44-pin devices; individual unimplemented bits should be interpreted as `-'. The PLLEN bit is only available in specific oscillator configurations; otherwise, it is disabled and reads as `0'. See Section 2.6.4 "PLL in INTOSC Modes". The RE3 bit is only available when Master Clear Reset is disabled (MCLRE Configuration bit = 0); otherwise, RE3 reads as `0'. This bit is read-only. RA6/RA7 and their associated latch and direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. DS39631E-page 66 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.3.5 STATUS REGISTER The STATUS register, shown in Register 5-2, contains the arithmetic status of the ALU. As with any other SFR, it can be the operand for any instruction. If the STATUS register is the destination for an instruction that affects the Z, DC, C, OV or N bits, the results of the instruction are not written; instead, the STATUS register is updated according to the instruction performed. Therefore, the result of an instruction with the STATUS register as its destination may be different than intended. As an example, CLRF STATUS will set the Z bit and leave the remaining Status bits unchanged (`000u u1uu'). REGISTER 5-2: U-0 For other instructions that do not affect Status bits, see the instruction set summaries in Table 24-2 and Table 24-3. Note: The C and DC bits operate as the borrow and digit borrow bits, respectively, in subtraction. STATUS REGISTER U-0 -- It is recommended that only BCF, BSF, SWAPF, MOVFF and MOVWF instructions are used to alter the STATUS register, because these instructions do not affect the Z, C, DC, OV or N bits in the STATUS register. U-0 -- -- R/W-x N R/W-x R/W-x OV Z R/W-x R/W-x (1) C(2) DC 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 N: Negative bit This bit is used for signed arithmetic (2's complement). It indicates whether the result was negative (ALU MSB = 1). 1 = Result was negative 0 = Result was positive bit 3 OV: Overflow bit This bit is used for signed arithmetic (2's complement). It indicates an overflow of the 7-bit magnitude which causes the sign bit (bit 7) to change state. 1 = Overflow occurred for signed arithmetic (in this arithmetic operation) 0 = No overflow occurred bit 2 Z: Zero bit 1 = The result of an arithmetic or logic operation is zero 0 = The result of an arithmetic or logic operation is not zero bit 1 DC: Digit Carry/borrow bit(1) For ADDWF, ADDLW, SUBLW and SUBWF instructions: 1 = A carry-out from the 4th low-order bit of the result occurred 0 = No carry-out from the 4th low-order bit of the result bit 0 C: Carry/borrow bit(2) For ADDWF, ADDLW, SUBLW and SUBWF instructions: 1 = A carry-out from the Most Significant bit of the result occurred 0 = No carry-out from the Most Significant bit of the result occurred Note 1: 2: For borrow, the polarity is reversed. A subtraction is executed by adding the 2's complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either bit 4 or bit 3 of the source register. For borrow, the polarity is reversed. A subtraction is executed by adding the 2's complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high or low-order bit of the source register. (c) 2008 Microchip Technology Inc. DS39631E-page 67 PIC18F2420/2520/4420/4520 5.4 Data Addressing Modes Note: The execution of some instructions in the core PIC18 instruction set are changed when the PIC18 extended instruction set is enabled. See Section 5.5 "Data Memory and the Extended Instruction Set" for more information. While the program memory can be addressed in only one way - through the program counter - information in the data memory space can be addressed in several ways. For most instructions, the addressing mode is fixed. Other instructions may use up to three modes, depending on which operands are used and whether or not the extended instruction set is enabled. The addressing modes are: * * * * Inherent Literal Direct Indirect A few instructions, such as MOVFF, include the entire 12-bit address (either source or destination) in their opcodes. In these cases, the BSR is ignored entirely. The destination of the operation's results is determined by the destination bit `d'. When `d' is `1', the results are stored back in the source register, overwriting its original contents. When `d' is `0', the results are stored in the W register. Instructions without the `d' argument have a destination that is implicit in the instruction; their destination is either the target register being operated on or the W register. 5.4.3 An additional addressing mode, Indexed Literal Offset, is available when the extended instruction set is enabled (XINST Configuration bit = 1). Its operation is discussed in greater detail in Section 5.5.1 "Indexed Addressing with Literal Offset". 5.4.1 The Access RAM bit `a' determines how the address is interpreted. When `a' is `1', the contents of the BSR (Section 5.3.1 "Bank Select Register (BSR)") are used with the address to determine the complete 12-bit address of the register. When `a' is `0', the address is interpreted as being a register in the Access Bank. Addressing that uses the Access RAM is sometimes also known as Direct Forced Addressing mode. INHERENT AND LITERAL ADDRESSING Many PIC18 control instructions do not need any argument at all; they either perform an operation that globally affects the device or they operate implicitly on one register. This addressing mode is known as Inherent Addressing. Examples include SLEEP, RESET and DAW. Other instructions work in a similar way but require an additional explicit argument in the opcode. This is known as Literal Addressing mode because they require some literal value as an argument. Examples include ADDLW and MOVLW, which respectively, add or move a literal value to the W register. Other examples include CALL and GOTO, which include a 20-bit program memory address. Indirect Addressing allows the user to access a location in data memory without giving a fixed address in the instruction. This is done by using File Select Registers (FSRs) as pointers to the locations to be read or written to. Since the FSRs are themselves located in RAM as Special Function Registers, they can also be directly manipulated under program control. This makes FSRs very useful in implementing data structures, such as tables and arrays in data memory. The registers for Indirect Addressing are also implemented with Indirect File Operands (INDFs) that permit automatic manipulation of the pointer value with auto-incrementing, auto-decrementing or offsetting with another value. This allows for efficient code, using loops, such as the example of clearing an entire RAM bank in Example 5-5. EXAMPLE 5-5: NEXT 5.4.2 INDIRECT ADDRESSING LFSR CLRF DIRECT ADDRESSING Direct Addressing specifies all or part of the source and/or destination address of the operation within the opcode itself. The options are specified by the arguments accompanying the instruction. BTFSS BRA CONTINUE HOW TO CLEAR RAM (BANK 1) USING INDIRECT ADDRESSING FSR0, 100h; POSTINC0 ; ; ; FSR0H, 1; All ; NEXT ; ; Clear INDF register then inc pointer done with Bank1? NO, clear next YES, continue In the core PIC18 instruction set, bit-oriented and byteoriented instructions use some version of Direct Addressing by default. All of these instructions include some 8-bit literal address as their Least Significant Byte. This address specifies either a register address in one of the banks of data RAM (Section 5.3.3 "General Purpose Register File") or a location in the Access Bank (Section 5.3.2 "Access Bank") as the data source for the instruction. DS39631E-page 68 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 5.4.3.1 FSR Registers and the INDF Operand 5.4.3.2 At the core of Indirect Addressing are three sets of registers: FSR0, FSR1 and FSR2. Each represents a pair of 8-bit registers, FSRnH and FSRnL. The four upper bits of the FSRnH register are not used so each FSR pair holds a 12-bit value. This represents a value that can address the entire range of the data memory in a linear fashion. The FSR register pairs, then, serve as pointers to data memory locations. In addition to the INDF operand, each FSR register pair also has four additional indirect operands. Like INDF, these are "virtual" registers that cannot be indirectly read or written to. Accessing these registers actually accesses the associated FSR register pair, but also performs a specific action on it stored value. They are: * POSTDEC: accesses the FSR value, then automatically decrements it by 1 afterwards * POSTINC: accesses the FSR value, then automatically increments it by 1 afterwards * PREINC: increments the FSR value by 1, then uses it in the operation * PLUSW: adds the signed value of the W register (range of -127 to 128) to that of the FSR and uses the new value in the operation. Indirect Addressing is accomplished with a set of Indirect File Operands, INDF0 through INDF2. These can be thought of as "virtual" registers: they are mapped in the SFR space but are not physically implemented. Reading or writing to a particular INDF register actually accesses its corresponding FSR register pair. A read from INDF1, for example, reads the data at the address indicated by FSR1H:FSR1L. Instructions that use the INDF registers as operands actually use the contents of their corresponding FSR as a pointer to the instruction's target. The INDF operand is just a convenient way of using the pointer. In this context, accessing an INDF register uses the value in the FSR registers without changing them. Similarly, accessing a PLUSW register gives the FSR value offset by that in the W register; neither value is actually changed in the operation. Accessing the other virtual registers changes the value of the FSR registers. Because Indirect Addressing uses a full 12-bit address, data RAM banking is not necessary. Thus, the current contents of the BSR and the Access RAM bit have no effect on determining the target address. FIGURE 5-8: FSR Registers and POSTINC, POSTDEC, PREINC and PLUSW Operations on the FSRs with POSTDEC, POSTINC and PREINC affect the entire register pair; that is, rollovers of the FSRnL register from FFh to 00h carry over to the FSRnH register. On the other hand, results of these operations do not change the value of any flags in the STATUS register (e.g., Z, N, OV, etc.). INDIRECT ADDRESSING 000h Using an instruction with one of the Indirect Addressing registers as the operand.... Bank 0 ADDWF, INDF1, 1 100h Bank 1 200h ...uses the 12-bit address stored in the FSR pair associated with that register.... 300h FSR1H:FSR1L 7 0 x x x x 1 1 1 0 7 0 Bank 2 Bank 3 through Bank 13 1 1 0 0 1 1 0 0 ...to determine the data memory location to be used in that operation. In this case, the FSR1 pair contains ECCh. This means the contents of location ECCh will be added to that of the W register and stored back in ECCh. E00h Bank 14 F00h FFFh Bank 15 Data Memory (c) 2008 Microchip Technology Inc. DS39631E-page 69 PIC18F2420/2520/4420/4520 The PLUSW register can be used to implement a form of Indexed Addressing in the data memory space. By manipulating the value in the W register, users can reach addresses that are fixed offsets from pointer addresses. In some applications, this can be used to implement some powerful program control structure, such as software stacks, inside of data memory. 5.4.3.3 Operations by FSRs on FSRs Indirect Addressing operations that target other FSRs or virtual registers represent special cases. For example, using an FSR to point to one of the virtual registers will not result in successful operations. As a specific case, assume that FSR0H:FSR0L contains FE7h, the address of INDF1. Attempts to read the value of the INDF1 using INDF0 as an operand will return 00h. Attempts to write to INDF1 using INDF0 as the operand will result in a NOP. On the other hand, using the virtual registers to write to an FSR pair may not occur as planned. In these cases, the value will be written to the FSR pair but without any incrementing or decrementing. Thus, writing to INDF2 or POSTDEC2 will write the same value to the FSR2H:FSR2L. Since the FSRs are physical registers mapped in the SFR space, they can be manipulated through all direct operations. Users should proceed cautiously when working on these registers, particularly if their code uses indirect addressing. Similarly, operations by Indirect Addressing are generally permitted on all other SFRs. Users should exercise the appropriate caution that they do not inadvertently change settings that might affect the operation of the device. 5.5 Data Memory and the Extended Instruction Set Enabling the PIC18 extended instruction set (XINST Configuration bit = 1) significantly changes certain aspects of data memory and its addressing. Specifically, the use of the Access Bank for many of the core PIC18 instructions is different; this is due to the introduction of a new addressing mode for the data memory space. What does not change is just as important. The size of the data memory space is unchanged, as well as its linear addressing. The SFR map remains the same. Core PIC18 instructions can still operate in both Direct and Indirect Addressing mode; inherent and literal instructions do not change at all. Indirect Addressing with FSR0 and FSR1 also remains unchanged. DS39631E-page 70 5.5.1 INDEXED ADDRESSING WITH LITERAL OFFSET Enabling the PIC18 extended instruction set changes the behavior of Indirect Addressing using the FSR2 register pair within Access RAM. Under the proper conditions, instructions that use the Access Bank - that is, most bit-oriented and byte-oriented instructions - can invoke a form of Indexed Addressing using an offset specified in the instruction. This special addressing mode is known as Indexed Addressing with Literal Offset, or Indexed Literal Offset mode. When using the extended instruction set, this addressing mode requires the following: * The use of the Access Bank is forced (`a' = 0) and * The file address argument is less than or equal to 5Fh. Under these conditions, the file address of the instruction is not interpreted as the lower byte of an address (used with the BSR in direct addressing), or as an 8-bit address in the Access Bank. Instead, the value is interpreted as an offset value to an Address Pointer, specified by FSR2. The offset and the contents of FSR2 are added to obtain the target address of the operation. 5.5.2 INSTRUCTIONS AFFECTED BY INDEXED LITERAL OFFSET MODE Any of the core PIC18 instructions that can use Direct Addressing are potentially affected by the Indexed Literal Offset Addressing mode. This includes all byte-oriented and bit-oriented instructions, or almost one-half of the standard PIC18 instruction set. Instructions that only use Inherent or Literal Addressing modes are unaffected. Additionally, byte-oriented and bit-oriented instructions are not affected if they do not use the Access Bank (Access RAM bit is `1'), or include a file address of 60h or above. Instructions meeting these criteria will continue to execute as before. A comparison of the different possible addressing modes when the extended instruction set is enabled in shown in Figure 5-9. Those who desire to use byte-oriented or bit-oriented instructions in the Indexed Literal Offset mode should note the changes to assembler syntax for this mode. This is described in more detail in Section 24.2.1 "Extended Instruction Syntax". (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 5-9: COMPARING ADDRESSING OPTIONS FOR BIT-ORIENTED AND BYTE-ORIENTED INSTRUCTIONS (EXTENDED INSTRUCTION SET ENABLED) EXAMPLE INSTRUCTION: ADDWF, f, d, a (Opcode: 0010 01da ffff ffff) When `a' = 0 and f 60h: The instruction executes in Direct Forced mode. `f' is interpreted as a location in the Access RAM between 060h and 0FFh. This is the same as locations 060h to 07Fh (Bank 0) and F80h to FFFh (Bank 15) of data memory. 000h Locations below 60h are not available in this addressing mode. F00h 060h 080h Bank 0 100h 00h Bank 1 through Bank 14 60h 80h Valid range for `f' FFh Access RAM Bank 15 F80h SFRs FFFh Data Memory When `a' = 0 and f 5Fh: The instruction executes in Indexed Literal Offset mode. `f' is interpreted as an offset to the address value in FSR2. The two are added together to obtain the address of the target register for the instruction. The address can be anywhere in the data memory space. Note that in this mode, the correct syntax is now: ADDWF [k], d where `k' is the same as `f'. 000h Bank 0 080h 100h 001001da ffffffff Bank 1 through Bank 14 FSR2H FSR2L F00h Bank 15 F80h SFRs FFFh Data Memory When `a' = 1 (all values of f): The instruction executes in Direct mode (also known as Direct Long mode). `f' is interpreted as a location in one of the 16 banks of the data memory space. The bank is designated by the Bank Select Register (BSR). The address can be in any implemented bank in the data memory space. BSR 00000000 000h Bank 0 080h 100h Bank 1 through Bank 14 001001da ffffffff F00h Bank 15 F80h SFRs FFFh Data Memory (c) 2008 Microchip Technology Inc. DS39631E-page 71 PIC18F2420/2520/4420/4520 5.5.3 MAPPING THE ACCESS BANK IN INDEXED LITERAL OFFSET MODE The use of Indexed Literal Offset Addressing mode effectively changes how the first 96 locations of Access RAM (00h to 5Fh) are mapped. Rather than containing just the contents of the bottom half of Bank 0, this mode maps the contents from Bank 0 and a user-defined "window" that can be located anywhere in the data memory space. The value of FSR2 establishes the lower boundary of the addresses mapped into the window, while the upper boundary is defined by FSR2 plus 95 (5Fh). Addresses in the Access RAM above 5Fh are mapped as previously described (see Section 5.3.2 "Access Bank"). An example of Access Bank remapping in this addressing mode is shown in Figure 5-10. FIGURE 5-10: Remapping of the Access Bank applies only to operations using the Indexed Literal Offset mode. Operations that use the BSR (Access RAM bit is `1') will continue to use Direct Addressing as before. 5.6 PIC18 Instruction Execution and the Extended Instruction Set Enabling the extended instruction set adds eight additional commands to the existing PIC18 instruction set. These instructions are executed as described in Section 24.2 "Extended Instruction Set". REMAPPING THE ACCESS BANK WITH INDEXED LITERAL OFFSET ADDRESSING Example Situation: ADDWF f, d, a FSR2H:FSR2L = 120h Locations in the region from the FSR2 Pointer (120h) to the pointer plus 05Fh (17Fh) are mapped to the bottom of the Access RAM (000h-05Fh). 000h 05Fh 07Fh Bank 0 100h 120h 17Fh 200h Bank 0 addresses below 5Fh can still be addressed by using the BSR. Bank 1 Window Bank 1 00h Bank 1 "Window" 5Fh Locations in Bank 0 from 060h to 07Fh are mapped, as usual, to the middle half of the Access Bank. Special Function Registers at F80h through FFFh are mapped to 80h through FFh, as usual. Bank 0 Bank 0 Bank 2 through Bank 14 7Fh 80h SFRs FFh Access Bank F00h Bank 15 F80h FFFh SFRs Data Memory DS39631E-page 72 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 6.0 FLASH PROGRAM MEMORY 6.1 Table Reads and Table Writes The Flash program memory is readable, writable and erasable during normal operation over the entire VDD range. In order to read and write program memory, there are two operations that allow the processor to move bytes between the program memory space and the data RAM: A read from program memory is executed on one byte at a time. A write to program memory is executed on blocks of 32 bytes at a time. Program memory is erased in blocks of 64 bytes at a time. A bulk erase operation may not be issued from user code. * Table Read (TBLRD) * Table Write (TBLWT) Writing or erasing program memory will cease instruction fetches until the operation is complete. The program memory cannot be accessed during the write or erase, therefore, code cannot execute. An internal programming timer terminates program memory writes and erases. A value written to program memory does not need to be a valid instruction. Executing a program memory location that forms an invalid instruction results in a NOP. The program memory space is 16 bits wide, while the data RAM space is 8 bits wide. Table reads and table writes move data between these two memory spaces through an 8-bit register (TABLAT). Table read operations retrieve data from program memory and places it into the data RAM space. Figure 6-1 shows the operation of a table read with program memory and data RAM. Table write operations store data from the data memory space into holding registers in program memory. The procedure to write the contents of the holding registers into program memory is detailed in Section 6.5 "Writing to Flash Program Memory". Figure 6-2 shows the operation of a table write with program memory and data RAM. Table operations work with byte entities. A table block containing data, rather than program instructions, is not required to be word aligned. Therefore, a table block can start and end at any byte address. If a table write is being used to write executable code into program memory, program instructions will need to be word aligned. FIGURE 6-1: TABLE READ OPERATION Instruction: TBLRD* Program Memory Table Pointer(1) TBLPTRU TBLPTRH Table Latch (8-bit) TBLPTRL TABLAT Program Memory (TBLPTR) Note 1: The Table Pointer register points to a byte in program memory. (c) 2008 Microchip Technology Inc. DS39631E-page 73 PIC18F2420/2520/4420/4520 FIGURE 6-2: TABLE WRITE OPERATION Instruction: TBLWT* Program Memory Holding Registers Table Pointer(1) TBLPTRU TBLPTRH Table Latch (8-bit) TBLPTRL TABLAT Program Memory (TBLPTR) Note1: The Table Pointer actually points to one of 32 holding registers, the address of which is determined by TBLPTRL<4:0>. The process for physically writing data to the program memory array is discussed in Section 6.5 "Writing to Flash Program Memory". 6.2 Control Registers Several control registers are used in conjunction with the TBLRD and TBLWT instructions. These include the: * * * * EECON1 register EECON2 register TABLAT register TBLPTR registers 6.2.1 EECON1 AND EECON2 REGISTERS The EECON1 register (Register 6-1) is the control register for memory accesses. The EECON2 register is not a physical register; it is used exclusively in the memory write and erase sequences. Reading EECON2 will read all `0's. The EEPGD control bit determines if the access will be a program or data EEPROM memory access. When clear, any subsequent operations will operate on the data EEPROM memory. When set, any subsequent operations will operate on the program memory. The CFGS control bit determines if the access will be to the Configuration/Calibration registers or to program memory/data EEPROM memory. When set, subsequent operations will operate on Configuration registers regardless of EEPGD (see Section 23.0 "Special Features of the CPU"). When clear, memory selection access is determined by EEPGD. DS39631E-page 74 The FREE bit, when set, will allow a program memory erase operation. When FREE is set, the erase operation is initiated on the next WR command. When FREE is clear, only writes are enabled. The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set in hardware when the WR bit is set and cleared when the internal programming timer expires and the write operation is complete. Note: During normal operation, the WRERR is read as `1'. This can indicate that a write operation was prematurely terminated by a Reset, or a write operation was attempted improperly. The WR control bit initiates write operations. The bit cannot be cleared, only set, in software; it is cleared in hardware at the completion of the write operation. Note: The EEIF interrupt flag bit (PIR2<4>) is set when the write is complete. It must be cleared in software. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 6-1: R/W-x EECON1: EEPROM CONTROL REGISTER 1 R/W-x EEPGD U-0 CFGS -- R/W-0 FREE R/W-x WRERR (1) R/W-0 R/S-0 R/S-0 WREN WR RD bit 7 bit 0 Legend: S = Settable bit (cannot be cleared in software) 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 EEPGD: Flash Program or Data EEPROM Memory Select bit 1 = Access Flash program memory 0 = Access data EEPROM memory bit 6 CFGS: Flash Program/Data EEPROM or Configuration Select bit 1 = Access Configuration registers 0 = Access Flash program or data EEPROM memory bit 5 Unimplemented: Read as `0' bit 4 FREE: Flash Row Erase Enable bit 1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared by completion of erase operation) 0 = Perform write only bit 3 WRERR: Flash Program/Data EEPROM Error Flag bit(1) 1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal operation, or an improper write attempt) 0 = The write operation completed bit 2 WREN: Flash Program/Data EEPROM Write Enable bit 1 = Allows write cycles to Flash program/data EEPROM 0 = Inhibits write cycles to Flash program/data EEPROM bit 1 WR: Write Control bit 1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle (The operation is self-timed and the bit is cleared by hardware once write is complete. The WR bit can only be set (not cleared) in software.) 0 = Write cycle to the EEPROM is complete bit 0 RD: Read Control bit 1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.) 0 = Does not initiate an EEPROM read Note 1: When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the error condition. (c) 2008 Microchip Technology Inc. DS39631E-page 75 PIC18F2420/2520/4420/4520 6.2.2 TABLAT - TABLE LATCH REGISTER 6.2.4 The Table Latch (TABLAT) is an 8-bit register mapped into the SFR space. The Table Latch register is used to hold 8-bit data during data transfers between program memory and data RAM. 6.2.3 TBLPTR is used in reads, writes and erases of the Flash program memory. When a TBLRD is executed, all 22 bits of the TBLPTR determine which byte is read from program memory into TABLAT. TBLPTR - TABLE POINTER REGISTER When a TBLWT is executed, the five LSbs of the Table Pointer register (TBLPTR<4:0>) determine which of the 32 program memory holding registers is written to. When the timed write to program memory begins (via the WR bit), the 16 MSbs of the TBLPTR (TBLPTR<21:6>) determine which program memory block of 32 bytes is written to. For more detail, see Section 6.5 "Writing to Flash Program Memory". The Table Pointer (TBLPTR) register addresses a byte within the program memory. The TBLPTR is comprised of three SFR registers: Table Pointer Upper Byte, Table Pointer High Byte and Table Pointer Low Byte (TBLPTRU:TBLPTRH:TBLPTRL). These three registers join to form a 22-bit wide pointer. The low-order 21 bits allow the device to address up to 2 Mbytes of program memory space. The 22nd bit allows access to the device ID, the user ID and the Configuration bits. When an erase of program memory is executed, the 16 MSbs of the Table Pointer register (TBLPTR<21:6>) point to the 64-byte block that will be erased. The Least Significant bits (TBLPTR<5:0>) are ignored. The Table Pointer register, TBLPTR, is used by the TBLRD and TBLWT instructions. These instructions can update the TBLPTR in one of four ways based on the table operation. These operations are shown in Table 6-1. These operations on the TBLPTR only affect the low-order 21 bits. TABLE 6-1: TABLE POINTER BOUNDARIES Figure 6-3 describes the relevant boundaries of TBLPTR based on Flash program memory operations. TABLE POINTER OPERATIONS WITH TBLRD AND TBLWT INSTRUCTIONS Example Operation on Table Pointer TBLRD* TBLWT* TBLPTR is not modified TBLRD*+ TBLWT*+ TBLPTR is incremented after the read/write TBLRD*TBLWT*- TBLPTR is decremented after the read/write TBLRD+* TBLWT+* TBLPTR is incremented before the read/write FIGURE 6-3: 21 TABLE POINTER BOUNDARIES BASED ON OPERATION TBLPTRU 16 15 TBLPTRH 8 7 TBLPTRL 0 TABLE ERASE TBLPTR<21:6> TABLE WRITE - TBLPTR<21:5> TABLE READ - TBLPTR<21:0> DS39631E-page 76 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 6.3 Reading the Flash Program Memory The TBLRD instruction is used to retrieve data from program memory and places it into data RAM. Table reads from program memory are performed one byte at a time. FIGURE 6-4: TBLPTR points to a byte address in program space. Executing TBLRD places the byte pointed to into TABLAT. In addition, TBLPTR can be modified automatically for the next table read operation. The internal program memory is typically organized by words. The Least Significant bit of the address selects between the high and low bytes of the word. Figure 6-4 shows the interface between the internal program memory and the TABLAT. READS FROM FLASH PROGRAM MEMORY Program Memory (Even Byte Address) (Odd Byte Address) TBLPTR = xxxxx1 Instruction Register (IR) EXAMPLE 6-1: FETCH TBLRD TBLPTR = xxxxx0 TABLAT Read Register READING A FLASH PROGRAM MEMORY WORD MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL ; Load TBLPTR with the base ; address of the word READ_WORD TBLRD*+ MOVF MOVWF TBLRD*+ MOVFW MOVF TABLAT, W WORD_EVEN TABLAT, W WORD_ODD (c) 2008 Microchip Technology Inc. ; read into TABLAT and increment ; get data ; read into TABLAT and increment ; get data DS39631E-page 77 PIC18F2420/2520/4420/4520 6.4 Erasing Flash Program Memory The minimum erase block is 32 words or 64 bytes. Only through the use of an external programmer, or through ICSP control, can larger blocks of program memory be bulk erased. Word erase in the Flash array is not supported. When initiating an erase sequence from the microcontroller itself, a block of 64 bytes of program memory is erased. The Most Significant 16 bits of the TBLPTR<21:6> point to the block being erased. TBLPTR<5:0> are ignored. 6.4.1 The sequence of events for erasing a block of internal program memory location is: 1. 2. The EECON1 register commands the erase operation. The EEPGD bit must be set to point to the Flash program memory. The WREN bit must be set to enable write operations. The FREE bit is set to select an erase operation. 3. 4. 5. 6. For protection, the write initiate sequence for EECON2 must be used. 7. A long write is necessary for erasing the internal Flash. Instruction execution is halted while in a long write cycle. The long write will be terminated by the internal programming timer. EXAMPLE 6-2: FLASH PROGRAM MEMORY ERASE SEQUENCE 8. Load Table Pointer register with address of row being erased. Set the EECON1 register for the erase operation: * set EEPGD bit to point to program memory; * clear the CFGS bit to access program memory; * set WREN bit to enable writes; * set FREE bit to enable the erase. Disable interrupts. Write 55h to EECON2. Write 0AAh to EECON2. Set the WR bit. This will begin the row erase cycle. The CPU will stall for duration of the erase (about 2 ms using internal timer). Re-enable interrupts. ERASING A FLASH PROGRAM MEMORY ROW MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL ; load TBLPTR with the base ; address of the memory block BSF BCF BSF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BSF EECON1, EECON1, EECON1, EECON1, INTCON, 55h EECON2 0AAh EECON2 EECON1, INTCON, ; ; ; ; ; ERASE_ROW Required Sequence DS39631E-page 78 EEPGD CFGS WREN FREE GIE point to Flash program memory access Flash program memory enable write to memory enable Row Erase operation disable interrupts ; write 55h WR GIE ; write 0AAh ; start erase (CPU stall) ; re-enable interrupts (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 6.5 Writing to Flash Program Memory The minimum programming block is 16 words or 32 bytes. Word or byte programming is not supported. Table writes are used internally to load the holding registers needed to program the Flash memory. There are 32 holding registers used by the table writes for programming. Since the Table Latch (TABLAT) is only a single byte, the TBLWT instruction may need to be executed 32 times for each programming operation. All of the table write operations will essentially be short writes because only the holding registers are written. At the end of updating the 32 holding registers, the EECON1 register must be written to in order to start the programming operation with a long write. FIGURE 6-5: The long write is necessary for programming the internal Flash. Instruction execution is halted while in a long write cycle. The long write will be terminated by the internal programming timer. The EEPROM on-chip timer controls the write time. The write/erase voltages are generated by an on-chip charge pump, rated to operate over the voltage range of the device. Note: The default value of the holding registers on device Resets and after write operations is FFh. A write of FFh to a holding register does not modify that byte. This means individual bytes of program memory may be modified, provided that the change does not attempt to change any bit from a `0' to a `1'. When modifying individual bytes, it is not necessary to load all 32 holding registers before executing a write operation. TABLE WRITES TO FLASH PROGRAM MEMORY TABLAT Write Register 8 8 TBLPTR = xxxxx0 TBLPTR = xxxxx1 Holding Register 8 TBLPTR = xxxx3F TBLPTR = xxxxx2 Holding Register 8 Holding Register Holding Register Program Memory 6.5.1 FLASH PROGRAM MEMORY WRITE SEQUENCE The sequence of events for programming an internal program memory location should be: 1. 2. 3. 4. 5. 6. 7. Read 64 bytes into RAM. Update data values in RAM as necessary. Load Table Pointer register with address being erased. Execute the row erase procedure. Load Table Pointer register with address of first byte being written. Write the 32 bytes into the holding registers with auto-increment. Set the EECON1 register for the write operation: * set EEPGD bit to point to program memory; * clear the CFGS bit to access program memory; * set WREN to enable byte writes. (c) 2008 Microchip Technology Inc. 8. 9. 10. 11. 12. Disable interrupts. Write 55h to EECON2. Write 0AAh to EECON2. Set the WR bit. This will begin the write cycle. The CPU will stall for duration of the write (about 2 ms using internal timer). 13. Re-enable interrupts. 14. Verify the memory (table read). This procedure will require about 6 ms to update one row of 64 bytes of memory. An example of the required code is given in Example 6-3. Note: Before setting the WR bit, the Table Pointer address needs to be within the intended address range of the 32 bytes in the holding register. DS39631E-page 79 PIC18F2420/2520/4420/4520 EXAMPLE 6-3: WRITING TO FLASH PROGRAM MEMORY MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF D'64 COUNTER BUFFER_ADDR_HIGH FSR0H BUFFER_ADDR_LOW FSR0L CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL TBLRD*+ MOVF MOVWF DECFSZ BRA TABLAT, W POSTINC0 COUNTER READ_BLOCK MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF DATA_ADDR_HIGH FSR0H DATA_ADDR_LOW FSR0L NEW_DATA_LOW POSTINC0 NEW_DATA_HIGH INDF0 ; number of bytes in erase block ; point to buffer ; Load TBLPTR with the base ; address of the memory block READ_BLOCK ; ; ; ; ; read into TABLAT, and inc get data store data done? repeat MODIFY_WORD ; point to buffer ; update buffer word ERASE_BLOCK MOVLW MOVWF MOVLW MOVWF MOVLW MOVWF BSF BCF BSF BSF BCF MOVLW Required MOVWF Sequence MOVLW MOVWF BSF BSF TBLRD*MOVLW MOVWF MOVLW MOVWF WRITE_BUFFER_BACK MOVLW MOVWF WRITE_BYTE_TO_HREGS MOVFF MOVWF TBLWT+* CODE_ADDR_UPPER TBLPTRU CODE_ADDR_HIGH TBLPTRH CODE_ADDR_LOW TBLPTRL EECON1, EEPGD EECON1, CFGS EECON1, WREN EECON1, FREE INTCON, GIE 55h EECON2 0AAh EECON2 EECON1, WR INTCON, GIE BUFFER_ADDR_HIGH FSR0H BUFFER_ADDR_LOW FSR0L ; ; ; ; ; point to Flash program memory access Flash program memory enable write to memory enable Row Erase operation disable interrupts ; write 55h ; ; ; ; ; write 0AAh start erase (CPU stall) re-enable interrupts dummy read decrement point to buffer D'32 COUNTER ; number of bytes in holding register POSTINC0, WREG TABLAT ; ; ; ; ; DECFSZ COUNTER BRA WRITE_WORD_TO_HREGS DS39631E-page 80 ; load TBLPTR with the base ; address of the memory block get low byte of buffer data present data to table latch write data, perform a short write to internal TBLWT holding register. loop until buffers are full (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 EXAMPLE 6-3: WRITING TO FLASH PROGRAM MEMORY (CONTINUED) PROGRAM_MEMORY BSF BCF BSF BCF MOVLW MOVWF MOVLW MOVWF BSF BSF BCF Required Sequence 6.5.2 EECON1, EECON1, EECON1, INTCON, 55h EECON2 0AAh EECON2 EECON1, INTCON, EECON1, EEPGD CFGS WREN GIE ; ; ; ; point to Flash program memory access Flash program memory enable write to memory disable interrupts ; write 55h ; ; ; ; WR GIE WREN write 0AAh start program (CPU stall) re-enable interrupts disable write to memory 6.5.4 WRITE VERIFY Depending on the application, good programming practice may dictate that the value written to the memory should be verified against the original value. This should be used in applications where excessive writes can stress bits near the specification limit. 6.5.3 UNEXPECTED TERMINATION OF WRITE OPERATION If a write is terminated by an unplanned event, such as loss of power or an unexpected Reset, the memory location just programmed should be verified and reprogrammed if needed. If the write operation is interrupted by a MCLR Reset or a WDT Time-out Reset during normal operation, the user can check the WRERR bit and rewrite the location(s) as needed. TABLE 6-2: PROTECTION AGAINST SPURIOUS WRITES To protect against spurious writes to Flash program memory, the write initiate sequence must also be followed. See Section 23.0 "Special Features of the CPU" for more detail. 6.6 Flash Program Operation During Code Protection See Section 23.5 "Program Verification and Code Protection" for details on code protection of Flash program memory. REGISTERS ASSOCIATED WITH PROGRAM FLASH MEMORY Name Bit 7 Bit 6 Bit 5 TBLPTRU -- -- bit 21 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Program Memory Table Pointer Upper Byte (TBLPTR<20:16>) Reset Values on page 49 TBLPTRH Program Memory Table Pointer High Byte (TBLPTR<15:8>) 49 TBLPTRL Program Memory Table Pointer Low Byte (TBLPTR<7:0>) 49 TABLAT 49 Program Memory Table Latch INTCON GIE/GIEH PEIE/GIEL TMR0IE EECON2 EEPROM Control Register 2 (not a physical register) INT0IE RBIE TMR0IF INT0IF RBIF 49 51 EECON1 EEPGD CFGS -- FREE WRERR WREN WR RD 51 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 Legend: -- = unimplemented, read as `0'. Shaded cells are not used during Flash/EEPROM access. (c) 2008 Microchip Technology Inc. DS39631E-page 81 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 82 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 7.0 DATA EEPROM MEMORY The data EEPROM is a nonvolatile memory array, separate from the data RAM and program memory, that is used for long-term storage of program data. It is not directly mapped in either the register file or program memory space but is indirectly addressed through the Special Function Registers (SFRs). The EEPROM is readable and writable during normal operation over the entire VDD range. Five SFRs are used to read and write to the data EEPROM as well as the program memory. They are: * * * * EECON1 EECON2 EEDATA EEADR The data EEPROM allows byte read and write. When interfacing to the data memory block, EEDATA holds the 8-bit data for read/write and the EEADR register holds the address of the EEPROM location being accessed. The EEPROM data memory is rated for high erase/write cycle endurance. A byte write automatically erases the location and writes the new data (erase-before-write). The write time is controlled by an on-chip timer; it will vary with voltage and temperature as well as from chip to chip. Please refer to parameter D122 (Table 26-1 in Section 26.0 "Electrical Characteristics") for exact limits. 7.1 EEADR Register The EEADR register is used to address the data EEPROM for read and write operations. The 8-bit range of the register can address a memory range of 256 bytes (00h to FFh). 7.2 EECON1 and EECON2 Registers Access to the data EEPROM is controlled by two registers: EECON1 and EECON2. These are the same registers which control access to the program memory and are used in a similar manner for the data EEPROM. (c) 2008 Microchip Technology Inc. The EECON1 register (Register 7-1) is the control register for data and program memory access. Control bit EEPGD determines if the access will be to program or data EEPROM memory. When clear, operations will access the data EEPROM memory. When set, program memory is accessed. Control bit, CFGS, determines if the access will be to the Configuration registers or to program memory/data EEPROM memory. When set, subsequent operations access Configuration registers. When CFGS is clear, the EEPGD bit selects either program Flash or data EEPROM memory. The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set in hardware when the WR bit is set and cleared when the internal programming timer expires and the write operation is complete. Note: During normal operation, the WRERR may read as `1'. This can indicate that a write operation was prematurely terminated by a Reset, or a write operation was attempted improperly. The WR control bit initiates write operations. The bit can be set but not cleared in software. It is only cleared in hardware at the completion of the write operation. Note: The EEIF interrupt flag bit (PIR2<4>) is set when the write is complete. It must be cleared in software. Control bits, RD and WR, start read and erase/write operations, respectively. These bits are set by firmware and cleared by hardware at the completion of the operation. The RD bit cannot be set when accessing program memory (EEPGD = 1). Program memory is read using table read instructions. See Section 6.1 "Table Reads and Table Writes" regarding table reads. The EECON2 register is not a physical register. It is used exclusively in the memory write and erase sequences. Reading EECON2 will read all `0's. DS39631E-page 83 PIC18F2420/2520/4420/4520 REGISTER 7-1: EECON1: EEPROM CONTROL REGISTER 1 R/W-x R/W-x U-0 R/W-0 R/W-x R/W-0 R/S-0 R/S-0 EEPGD CFGS -- FREE WRERR(1) WREN WR RD bit 7 bit 0 Legend: S = Settable bit (cannot be cleared in software) 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 EEPGD: Flash Program or Data EEPROM Memory Select bit 1 = Access Flash program memory 0 = Access data EEPROM memory bit 6 CFGS: Flash Program/Data EEPROM or Configuration Select bit 1 = Access Configuration registers 0 = Access Flash program or data EEPROM memory bit 5 Unimplemented: Read as `0' bit 4 FREE: Flash Row Erase Enable bit 1 = Erase the program memory row addressed by TBLPTR on the next WR command (cleared by completion of erase operation) 0 = Perform write only bit 3 WRERR: Flash Program/Data EEPROM Error Flag bit(1) 1 = A write operation is prematurely terminated (any Reset during self-timed programming in normal operation, or an improper write attempt) 0 = The write operation completed bit 2 WREN: Flash Program/Data EEPROM Write Enable bit 1 = Allows write cycles to Flash program/data EEPROM 0 = Inhibits write cycles to Flash program/data EEPROM bit 1 WR: Write Control bit 1 = Initiates a data EEPROM erase/write cycle or a program memory erase cycle or write cycle (The operation is self-timed and the bit is cleared by hardware once write is complete. The WR bit can only be set (not cleared) in software.) 0 = Write cycle to the EEPROM is complete bit 0 RD: Read Control bit 1 = Initiates an EEPROM read (Read takes one cycle. RD is cleared in hardware. The RD bit can only be set (not cleared) in software. RD bit cannot be set when EEPGD = 1 or CFGS = 1.) 0 = Does not initiate an EEPROM read Note 1: When a WRERR occurs, the EEPGD and CFGS bits are not cleared. This allows tracing of the error condition. DS39631E-page 84 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 7.3 Reading the Data EEPROM Memory To read a data memory location, the user must write the address to the EEADR register, clear the EEPGD control bit (EECON1<7>) and then set control bit, RD (EECON1<0>). The data is available on the very next instruction cycle; therefore, the EEDATA register can be read by the next instruction. EEDATA will hold this value until another read operation, or until it is written to by the user (during a write operation). The basic process is shown in Example 7-1. 7.4 Writing to the Data EEPROM Memory To write an EEPROM data location, the address must first be written to the EEADR register and the data written to the EEDATA register. The sequence in Example 7-2 must be followed to initiate the write cycle. The write will not begin if this sequence is not exactly followed (write 55h to EECON2, write 0AAh to EECON2, then set WR bit) for each byte. It is strongly recommended that interrupts be disabled during this code segment. EXAMPLE 7-1: MOVLW MOVWF BCF BCF BSF MOVF After a write sequence has been initiated, EECON1, EEADR and EEDATA cannot be modified. The WR bit will be inhibited from being set unless the WREN bit is set. Both WR and WREN cannot be set with the same instruction. At the completion of the write cycle, the WR bit is cleared in hardware and the EEPROM Interrupt Flag bit, EEIF, is set. The user may either enable this interrupt or poll this bit. EEIF must be cleared by software. 7.5 Write Verify Depending on the application, good programming practice may dictate that the value written to the memory should be verified against the original value. This should be used in applications where excessive writes can stress bits near the specification limit. DATA EEPROM READ DATA_EE_ADDR EEADR EECON1, EEPGD EECON1, CFGS EECON1, RD EEDATA, W EXAMPLE 7-2: Required Sequence Additionally, the WREN bit in EECON1 must be set to enable writes. This mechanism prevents accidental writes to data EEPROM due to unexpected code execution (i.e., runaway programs). The WREN bit should be kept clear at all times, except when updating the EEPROM. The WREN bit is not cleared by hardware. ; ; ; ; ; ; Data Memory Address to read Point to DATA memory Access EEPROM EEPROM Read W = EEDATA DATA EEPROM WRITE MOVLW MOVWF MOVLW MOVWF BCF BCF BSF DATA_EE_ADDR EEADR DATA_EE_DATA EEDATA EECON1, EEPGD EECON1, CFGS EECON1, WREN ; ; ; ; ; ; ; BCF MOVLW MOVWF MOVLW MOVWF BSF BSF INTCON, GIE 55h EECON2 0AAh EECON2 EECON1, WR INTCON, GIE ; ; ; ; ; ; ; BCF EECON1, WREN ; User code execution ; Disable writes on write complete (EEIF set) (c) 2008 Microchip Technology Inc. Data Memory Address to write Data Memory Value to write Point to DATA memory Access EEPROM Enable writes Disable Interrupts Write 55h Write 0AAh Set WR bit to begin write Enable Interrupts DS39631E-page 85 PIC18F2420/2520/4420/4520 7.6 Operation During Code-Protect Data EEPROM memory has its own code-protect bits in Configuration Words. External read and write operations are disabled if code protection is enabled. The microcontroller itself can both read and write to the internal data EEPROM, regardless of the state of the code-protect Configuration bit. Refer to Section 23.0 "Special Features of the CPU" for additional information. 7.7 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 implemented. On power-up, the WREN bit is cleared. In addition, writes to the EEPROM are blocked during the Power-up Timer period (TPWRT, parameter 33). 7.8 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). Frequently changing values will typically be updated more often than specification D124. If this is not the case, an array refresh must be performed. For this reason, variables that change infrequently (such as constants, IDs, calibration, etc.) should be stored in Flash program memory. A simple data EEPROM refresh routine is shown in Example 7-3. Note: If data EEPROM is only used to store constants and/or data that changes rarely, an array refresh is likely not required. See specification D124. The write initiate sequence and the WREN bit together help prevent an accidental write during brown-out, power glitch or software malfunction. EXAMPLE 7-3: DATA EEPROM REFRESH ROUTINE CLRF BCF BCF BCF BSF EEADR EECON1, EECON1, INTCON, EECON1, BSF MOVLW MOVWF MOVLW MOVWF BSF BTFSC BRA INCFSZ BRA EECON1, RD 55h EECON2 0AAh EECON2 EECON1, WR EECON1, WR $-2 EEADR, F LOOP BCF BSF EECON1, WREN INTCON, GIE CFGS EEPGD GIE WREN Loop DS39631E-page 86 ; ; ; ; ; ; ; ; ; ; ; ; ; Start at address 0 Set for memory Set for Data EEPROM Disable interrupts Enable writes Loop to refresh array Read current address Write 55h Write 0AAh Set WR bit to begin write Wait for write to complete ; Increment address ; Not zero, do it again ; Disable writes ; Enable interrupts (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 7-1: Name INTCON REGISTERS ASSOCIATED WITH DATA EEPROM MEMORY Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF Reset Values on page 49 EEADR EEPROM Address Register 51 EEDATA EEPROM Data Register 51 EECON2 EEPROM Control Register 2 (not a physical register) 51 EECON1 EEPGD CFGS -- FREE WRERR WREN WR RD 51 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 Legend: -- = unimplemented, read as `0'. Shaded cells are not used during Flash/EEPROM access. (c) 2008 Microchip Technology Inc. DS39631E-page 87 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 88 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 8.0 8 x 8 HARDWARE MULTIPLIER 8.1 Introduction EXAMPLE 8-1: MOVF MULWF All PIC18 devices include an 8 x 8 hardware multiplier as part of the ALU. The multiplier performs an unsigned operation and yields a 16-bit result that is stored in the product register pair, PRODH:PRODL. The multiplier's operation does not affect any flags in the STATUS register. ARG1, W ARG2 ; ; ARG1 * ARG2 -> ; PRODH:PRODL EXAMPLE 8-2: Making multiplication a hardware operation allows it to be completed in a single instruction cycle. This has the advantages of higher computational throughput and reduced code size for multiplication algorithms and allows the PIC18 devices to be used in many applications previously reserved for digital signal processors. A comparison of various hardware and software multiply operations, along with the savings in memory and execution time, is shown in Table 8-1. 8.2 8 x 8 UNSIGNED MULTIPLY ROUTINE 8 x 8 SIGNED MULTIPLY ROUTINE MOVF MULWF ARG1, W ARG2 BTFSC SUBWF ARG2, SB PRODH, F MOVF BTFSC SUBWF ARG2, W ARG1, SB PRODH, F ; ; ; ; ; ARG1 * ARG2 -> PRODH:PRODL Test Sign Bit PRODH = PRODH - ARG1 ; Test Sign Bit ; PRODH = PRODH ; - ARG2 Operation Example 8-1 shows the instruction sequence for an 8 x 8 unsigned multiplication. Only one instruction is required when one of the arguments is already loaded in the WREG register. Example 8-2 shows the sequence to do an 8 x 8 signed multiplication. To account for the sign bits of the arguments, each argument's Most Significant bit (MSb) is tested and the appropriate subtractions are done. TABLE 8-1: PERFORMANCE COMPARISON FOR VARIOUS MULTIPLY OPERATIONS Routine 8 x 8 unsigned 8 x 8 signed 16 x 16 unsigned 16 x 16 signed Program Memory (Words) Cycles (Max) Without hardware multiply 13 Hardware multiply 1 Without hardware multiply 33 Hardware multiply 6 Without hardware multiply Hardware multiply Multiply Method Time @ 40 MHz @ 10 MHz @ 4 MHz 69 6.9 s 27.6 s 69 s 1 100 ns 400 ns 1 s 91 9.1 s 36.4 s 91 s 6 600 ns 2.4 s 6 s 21 242 24.2 s 96.8 s 242 s 28 28 2.8 s 11.2 s 28 s Without hardware multiply 52 254 25.4 s 102.6 s 254 s Hardware multiply 35 40 4.0 s 16.0 s 40 s (c) 2008 Microchip Technology Inc. DS39631E-page 89 PIC18F2420/2520/4420/4520 Example 8-3 shows the sequence to do a 16 x 16 unsigned multiplication. Equation 8-1 shows the algorithm that is used. The 32-bit result is stored in four registers (RES<3:0>). EQUATION 8-1: RES<3:0> = = 16 x 16 UNSIGNED MULTIPLICATION ALGORITHM ARG1H:ARG1L * ARG2H:ARG2L (ARG1H * ARG2H * 216) + (ARG1H * ARG2L * 28) + (ARG1L * ARG2H * 28) + (ARG1L * ARG2L) EXAMPLE 8-3: EQUATION 8-2: RES<3:0> = ARG1H:ARG1L * ARG2H:ARG2L = (ARG1H * ARG2H * 216) + (ARG1H * ARG2L * 28) + (ARG1L * ARG2H * 28) + (ARG1L * ARG2L) + (-1 * ARG2H<7> * ARG1H:ARG1L * 216) + (-1 * ARG1H<7> * ARG2H:ARG2L * 216) EXAMPLE 8-4: 16 x 16 UNSIGNED MULTIPLY ROUTINE MOVF MULWF ARG1L, W ARG2L MOVFF MOVFF PRODH, RES1 PRODL, RES0 MOVF MULWF ARG1H, W ARG2H MOVFF MOVFF PRODH, RES3 PRODL, RES2 MOVF MULWF ARG1L, W ARG2H MOVF ADDWF MOVF ADDWFC CLRF ADDWFC PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F MOVF MULWF ARG1H, W ARG2L MOVF ADDWF MOVF ADDWFC CLRF ADDWFC PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F ; ARG1L * ARG2L-> ; PRODH:PRODL ; ; ARG1L * ARG2H-> PRODH:PRODL Add cross products ARG1H * ARG2L-> PRODH:PRODL Add cross products Example 8-4 shows the sequence to do a 16 x 16 signed multiply. Equation 8-2 shows the algorithm used. The 32-bit result is stored in four registers (RES<3:0>). To account for the sign bits of the arguments, the MSb for each argument pair is tested and the appropriate subtractions are done. DS39631E-page 90 ARG1L, W ARG2L MOVFF MOVFF PRODH, RES1 PRODL, RES0 MOVF MULWF ARG1H, W ARG2H MOVFF MOVFF PRODH, RES3 PRODL, RES2 MOVF MULWF ARG1L, W ARG2H MOVF ADDWF MOVF ADDWFC CLRF ADDWFC PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F MOVF MULWF ARG1H, W ARG2L MOVF ADDWF MOVF ADDWFC CLRF ADDWFC PRODL, W RES1, F PRODH, W RES2, F WREG RES3, F BTFSS BRA MOVF SUBWF MOVF SUBWFB ARG2H, 7 SIGN_ARG1 ARG1L, W RES2 ARG1H, W RES3 ; ARG2H:ARG2L neg? ; no, check ARG1 ; ; ; ARG1H, 7 CONT_CODE ARG2L, W RES2 ARG2H, W RES3 ; ARG1H:ARG1L neg? ; no, done ; ; ; ; ARG1L * ARG2L -> ; PRODH:PRODL ; ; ; ARG1H * ARG2H -> ; PRODH:PRODL ; ; ; ; ; ; ; ; ; ; ARG1L * ARG2H -> PRODH:PRODL Add cross products ; ; ; ; ; ; ; ; ; ; ; MOVF MULWF ; ; ; ; ; ; ; ; ; ; 16 x 16 SIGNED MULTIPLY ROUTINE ; ; ; ARG1H * ARG2H-> ; PRODH:PRODL ; ; 16 x 16 SIGNED MULTIPLICATION ALGORITHM ; ; ; ; ; ; ; ; ; ARG1H * ARG2L -> PRODH:PRODL Add cross products ; ; SIGN_ARG1 BTFSS BRA MOVF SUBWF MOVF SUBWFB ; CONT_CODE : (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 9.0 INTERRUPTS The PIC18F2420/2520/4420/4520 devices have multiple interrupt sources and an interrupt priority feature that allows most interrupt sources to be assigned a high-priority level or a low-priority level. The high-priority interrupt vector is at 0008h and the lowpriority interrupt vector is at 0018h. High-priority interrupt events will interrupt any low-priority interrupts that may be in progress. There are ten registers which are used to control interrupt operation. These registers are: * * * * * * * RCON INTCON INTCON2 INTCON3 PIR1, PIR2 PIE1, PIE2 IPR1, IPR2 It is recommended that the Microchip header files supplied with MPLAB(R) IDE be used for the symbolic bit names in these registers. This allows the assembler/ compiler to automatically take care of the placement of these bits within the specified register. In general, interrupt sources have three bits to control their operation. They are: * Flag bit to indicate that an interrupt event occurred * Enable bit that allows program execution to branch to the interrupt vector address when the flag bit is set * Priority bit to select high priority or low priority The interrupt priority feature is enabled by setting the IPEN bit (RCON<7>). When interrupt priority is enabled, there are two bits which enable interrupts globally. Setting the GIEH bit (INTCON<7>) enables all interrupts that have the priority bit set (high priority). Setting the GIEL bit (INTCON<6>) enables all interrupts that have the priority bit cleared (low priority). When the interrupt flag, enable bit and appropriate global interrupt enable bit are set, the interrupt will vector immediately to address 0008h or 0018h, depending on the priority bit setting. Individual interrupts can be disabled through their corresponding enable bits. (c) 2008 Microchip Technology Inc. When the IPEN bit is cleared (default state), the interrupt priority feature is disabled and interrupts are compatible with PIC(R) mid-range devices. In Compatibility mode, the interrupt priority bits for each source have no effect. INTCON<6> is the PEIE bit, which enables/disables all peripheral interrupt sources. INTCON<7> is the GIE bit, which enables/disables all interrupt sources. All interrupts branch to address 0008h in Compatibility mode. When an interrupt is responded to, the global interrupt enable bit is cleared to disable further interrupts. If the IPEN bit is cleared, this is the GIE bit. If interrupt priority levels are used, this will be either the GIEH or GIEL bit. High-priority interrupt sources can interrupt a lowpriority interrupt. Low-priority interrupts are not processed while high-priority interrupts are in progress. The return address is pushed onto the stack and the PC is loaded with the interrupt vector address (0008h or 0018h). Once in the Interrupt Service Routine, the source(s) of the interrupt can be determined by polling the interrupt flag bits. The interrupt flag bits must be cleared in software before re-enabling interrupts to avoid recursive interrupts. The "return from interrupt" instruction, RETFIE, exits the interrupt routine and sets the GIE bit (GIEH or GIEL if priority levels are used), which re-enables interrupts. For external interrupt events, such as the INTx pins or the PORTB input change interrupt, the interrupt latency will be three to four instruction cycles. The exact latency is the same for one or two-cycle instructions. Individual interrupt flag bits are set, regardless of the status of their corresponding enable bit or the GIE bit. Note: Do not use the MOVFF instruction to modify any of the interrupt control registers while any interrupt is enabled. Doing so may cause erratic microcontroller behavior. DS39631E-page 91 PIC18F2420/2520/4420/4520 FIGURE 9-1: PIC18 INTERRUPT LOGIC Wake-up if in Idle or Sleep modes TMR0IF TMR0IE TMR0IP RBIF RBIE RBIP INT0IF INT0IE Interrupt to CPU Vector to Location 0008h INT1IF INT1IE INT1IP INT2IF INT2IE INT2IP SSPIF SSPIE SSPIP GIE/GIEH ADIF ADIE ADIP IPEN IPEN RCIF RCIE RCIP PEIE/GIEL IPEN Additional Peripheral Interrupts High-Priority Interrupt Generation Low-Priority Interrupt Generation SSPIF SSPIE SSPIP Interrupt to CPU Vector to Location 0018h TMR0IF TMR0IE TMR0IP ADIF ADIE ADIP RBIF RBIE RBIP RCIF RCIE RCIP Additional Peripheral Interrupts GIE/GIEH PEIE/GIE INT1IF INT1IE INT1IP INT2IF INT2IE INT2IP DS39631E-page 92 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 9.1 INTCON Registers Note: The INTCON registers are readable and writable registers, which contain various enable, priority and flag bits. REGISTER 9-1: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling. INTCON: INTERRUPT CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-x GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF(1) 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/GIEH: Global Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked interrupts 0 = Disables all interrupts When IPEN = 1: 1 = Enables all high-priority interrupts 0 = Disables all interrupts bit 6 PEIE/GIEL: Peripheral Interrupt Enable bit When IPEN = 0: 1 = Enables all unmasked peripheral interrupts 0 = Disables all peripheral interrupts When IPEN = 1: 1 = Enables all low-priority peripheral interrupts 0 = Disables all low-priority peripheral interrupts bit 5 TMR0IE: TMR0 Overflow Interrupt Enable bit 1 = Enables the TMR0 overflow interrupt 0 = Disables the TMR0 overflow interrupt bit 4 INT0IE: INT0 External Interrupt Enable bit 1 = Enables the INT0 external interrupt 0 = Disables the INT0 external interrupt bit 3 RBIE: RB Port Change Interrupt Enable bit 1 = Enables the RB port change interrupt 0 = Disables the RB port change interrupt bit 2 TMR0IF: TMR0 Overflow Interrupt Flag bit 1 = TMR0 register has overflowed (must be cleared in software) 0 = TMR0 register did not overflow bit 1 INT0IF: INT0 External Interrupt Flag bit 1 = The INT0 external interrupt occurred (must be cleared in software) 0 = The INT0 external interrupt did not occur bit 0 RBIF: RB Port Change Interrupt Flag bit(1) 1 = At least one of the RB<7:4> pins changed state (must be cleared in software) 0 = None of the RB<7:4> pins have changed state Note 1: A mismatch condition will continue to set this bit. Reading PORTB will end the mismatch condition and allow the bit to be cleared. (c) 2008 Microchip Technology Inc. DS39631E-page 93 PIC18F2420/2520/4420/4520 REGISTER 9-2: INTCON2: INTERRUPT CONTROL REGISTER 2 R/W-1 R/W-1 R/W-1 R/W-1 U-0 R/W-1 U-0 R/W-1 RBPU INTEDG0 INTEDG1 INTEDG2 -- TMR0IP -- RBIP bit 7 bit 0 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 bit 7 RBPU: PORTB Pull-up Enable bit 1 = All PORTB pull-ups are disabled 0 = PORTB pull-ups are enabled by individual port latch values bit 6 INTEDG0: External Interrupt 0 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 5 INTEDG1: External Interrupt 1 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 4 INTEDG2: External Interrupt 2 Edge Select bit 1 = Interrupt on rising edge 0 = Interrupt on falling edge bit 3 Unimplemented: Read as `0' bit 2 TMR0IP: TMR0 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority bit 1 Unimplemented: Read as `0' bit 0 RBIP: RB Port Change Interrupt Priority bit 1 = High priority 0 = Low priority Note: x = Bit is unknown Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling. DS39631E-page 94 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 9-3: INTCON3: INTERRUPT CONTROL REGISTER 3 R/W-1 R/W-1 U-0 R/W-0 R/W-0 U-0 R/W-0 R/W-0 INT2IP INT1IP -- INT2IE INT1IE -- INT2IF INT1IF 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 bit 7 INT2IP: INT2 External Interrupt Priority bit 1 = High priority 0 = Low priority bit 6 INT1IP: INT1 External Interrupt Priority bit 1 = High priority 0 = Low priority bit 5 Unimplemented: Read as `0' bit 4 INT2IE: INT2 External Interrupt Enable bit 1 = Enables the INT2 external interrupt 0 = Disables the INT2 external interrupt bit 3 INT1IE: INT1 External Interrupt Enable bit 1 = Enables the INT1 external interrupt 0 = Disables the INT1 external interrupt bit 2 Unimplemented: Read as `0' bit 1 INT2IF: INT2 External Interrupt Flag bit 1 = The INT2 external interrupt occurred (must be cleared in software) 0 = The INT2 external interrupt did not occur bit 0 INT1IF: INT1 External Interrupt Flag bit 1 = The INT1 external interrupt occurred (must be cleared in software) 0 = The INT1 external interrupt did not occur Note: x = Bit is unknown Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit. User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. This feature allows for software polling. (c) 2008 Microchip Technology Inc. DS39631E-page 95 PIC18F2420/2520/4420/4520 9.2 PIR Registers The PIR registers contain the individual flag bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Request Flag registers (PIR1 and PIR2). REGISTER 9-4: Note 1: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the Global Interrupt Enable bit, GIE (INTCON<7>). 2: User software should ensure the appropriate interrupt flag bits are cleared prior to enabling an interrupt and after servicing that interrupt. PIR1: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 1 R/W-0 R/W-0 R-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF bit 7 bit 0 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 PSPIF: Parallel Slave Port Read/Write Interrupt Flag bit(1) 1 = A read or a write operation has taken place (must be cleared in software) 0 = No read or write has occurred bit 6 ADIF: A/D Converter Interrupt Flag bit 1 = An A/D conversion completed (must be cleared in software) 0 = The A/D conversion is not complete bit 5 RCIF: EUSART Receive Interrupt Flag bit 1 = The EUSART receive buffer, RCREG, is full (cleared when RCREG is read) 0 = The EUSART receive buffer is empty bit 4 TXIF: EUSART Transmit Interrupt Flag bit 1 = The EUSART transmit buffer, TXREG, is empty (cleared when TXREG is written) 0 = The EUSART transmit buffer is full bit 3 SSPIF: Master Synchronous Serial Port Interrupt Flag bit 1 = The transmission/reception is complete (must be cleared in software) 0 = Waiting to transmit/receive bit 2 CCP1IF: CCP1 Interrupt Flag bit Capture mode: 1 = A TMR1 register capture occurred (must be cleared in software) 0 = No TMR1 register capture occurred Compare mode: 1 = A TMR1 register compare match occurred (must be cleared in software) 0 = No TMR1 register compare match occurred PWM mode: Unused in this mode. bit 1 TMR2IF: TMR2 to PR2 Match Interrupt Flag bit 1 = TMR2 to PR2 match occurred (must be cleared in software) 0 = No TMR2 to PR2 match occurred bit 0 TMR1IF: TMR1 Overflow Interrupt Flag bit 1 = TMR1 register overflowed (must be cleared in software) 0 = TMR1 register did not overflow Note 1: This bit is unimplemented on 28-pin devices and will read as `0'. DS39631E-page 96 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 9-5: PIR2: PERIPHERAL INTERRUPT REQUEST (FLAG) REGISTER 2 R/W-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 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 OSCFIF: Oscillator Fail Interrupt Flag bit 1 = Device oscillator failed, clock input has changed to INTOSC (must be cleared in software) 0 = Device clock operating bit 6 CMIF: Comparator Interrupt Flag bit 1 = Comparator input has changed (must be cleared in software) 0 = Comparator input has not changed bit 5 Unimplemented: Read as `0' bit 4 EEIF: Data EEPROM/Flash Write Operation Interrupt Flag bit 1 = The write operation is complete (must be cleared in software) 0 = The write operation is not complete or has not been started bit 3 BCLIF: Bus Collision Interrupt Flag bit 1 = A bus collision occurred (must be cleared in software) 0 = No bus collision occurred bit 2 HLVDIF: High/Low-Voltage Detect Interrupt Flag bit 1 = A high/low-voltage condition occurred (direction determined by VDIRMAG bit, HLVDCON<7>) 0 = A high/low-voltage condition has not occurred bit 1 TMR3IF: TMR3 Overflow Interrupt Flag bit 1 = TMR3 register overflowed (must be cleared in software) 0 = TMR3 register did not overflow bit 0 CCP2IF: CCP2 Interrupt Flag bit Capture mode: 1 = A TMR1 register capture occurred (must be cleared in software) 0 = No TMR1 register capture occurred Compare mode: 1 = A TMR1 register compare match occurred (must be cleared in software) 0 = No TMR1 register compare match occurred PWM mode: Unused in this mode. (c) 2008 Microchip Technology Inc. DS39631E-page 97 PIC18F2420/2520/4420/4520 9.3 PIE Registers The PIE registers contain the individual enable bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Enable registers (PIE1 and PIE2). When IPEN = 0, the PEIE bit must be set to enable any of these peripheral interrupts. REGISTER 9-6: R/W-0 PIE1: PERIPHERAL INTERRUPT ENABLE REGISTER 1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE (1) PSPIE 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 bit 7 PSPIE: Parallel Slave Port Read/Write Interrupt Enable bit(1) 1 = Enables the PSP read/write interrupt 0 = Disables the PSP read/write interrupt bit 6 ADIE: A/D Converter Interrupt Enable bit 1 = Enables the A/D interrupt 0 = Disables the A/D interrupt bit 5 RCIE: EUSART Receive Interrupt Enable bit 1 = Enables the EUSART receive interrupt 0 = Disables the EUSART receive interrupt bit 4 TXIE: EUSART Transmit Interrupt Enable bit 1 = Enables the EUSART transmit interrupt 0 = Disables the EUSART transmit interrupt bit 3 SSPIE: Master Synchronous Serial Port Interrupt Enable bit 1 = Enables the MSSP interrupt 0 = Disables the MSSP interrupt bit 2 CCP1IE: CCP1 Interrupt Enable bit 1 = Enables the CCP1 interrupt 0 = Disables the CCP1 interrupt bit 1 TMR2IE: TMR2 to PR2 Match Interrupt Enable bit 1 = Enables the TMR2 to PR2 match interrupt 0 = Disables the TMR2 to PR2 match interrupt bit 0 TMR1IE: TMR1 Overflow Interrupt Enable bit 1 = Enables the TMR1 overflow interrupt 0 = Disables the TMR1 overflow interrupt Note 1: x = Bit is unknown This bit is unimplemented on 28-pin devices and will read as `0'. DS39631E-page 98 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 9-7: PIE2: PERIPHERAL INTERRUPT ENABLE REGISTER 2 R/W-0 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 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 bit 7 OSCFIE: Oscillator Fail Interrupt Enable bit 1 = Enabled 0 = Disabled bit 6 CMIE: Comparator Interrupt Enable bit 1 = Enabled 0 = Disabled bit 5 Unimplemented: Read as `0' bit 4 EEIE: Data EEPROM/Flash Write Operation Interrupt Enable bit 1 = Enabled 0 = Disabled bit 3 BCLIE: Bus Collision Interrupt Enable bit 1 = Enabled 0 = Disabled bit 2 HLVDIE: High/Low-Voltage Detect Interrupt Enable bit 1 = Enabled 0 = Disabled bit 1 TMR3IE: TMR3 Overflow Interrupt Enable bit 1 = Enabled 0 = Disabled bit 0 CCP2IE: CCP2 Interrupt Enable bit 1 = Enabled 0 = Disabled (c) 2008 Microchip Technology Inc. x = Bit is unknown DS39631E-page 99 PIC18F2420/2520/4420/4520 9.4 IPR Registers The IPR registers contain the individual priority bits for the peripheral interrupts. Due to the number of peripheral interrupt sources, there are two Peripheral Interrupt Priority registers (IPR1 and IPR2). Using the priority bits requires that the Interrupt Priority Enable (IPEN) bit be set. REGISTER 9-8: R/W-1 IPR1: PERIPHERAL INTERRUPT PRIORITY REGISTER 1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP (1) PSPIP 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 bit 7 PSPIP: Parallel Slave Port Read/Write Interrupt Priority bit(1) 1 = High priority 0 = Low priority bit 6 ADIP: A/D Converter Interrupt Priority bit 1 = High priority 0 = Low priority bit 5 RCIP: EUSART Receive Interrupt Priority bit 1 = High priority 0 = Low priority bit 4 TXIP: EUSART Transmit Interrupt Priority bit x = Bit is unknown 1 = High priority 0 = Low priority bit 3 SSPIP: Master Synchronous Serial Port Interrupt Priority bit 1 = High priority 0 = Low priority bit 2 CCP1IP: CCP1 Interrupt Priority bit 1 = High priority 0 = Low priority bit 1 TMR2IP: TMR2 to PR2 Match Interrupt Priority bit 1 = High priority 0 = Low priority bit 0 TMR1IP: TMR1 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority Note 1: This bit is unimplemented on 28-pin devices and will read as `0'. DS39631E-page 100 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 9-9: IPR2: PERIPHERAL INTERRUPT PRIORITY REGISTER 2 R/W-1 R/W-1 U-0 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 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 bit 7 OSCFIP: Oscillator Fail Interrupt Priority bit 1 = High priority 0 = Low priority bit 6 CMIP: Comparator Interrupt Priority bit 1 = High priority 0 = Low priority bit 5 Unimplemented: Read as `0' bit 4 EEIP: Data EEPROM/Flash Write Operation Interrupt Priority bit 1 = High priority 0 = Low priority bit 3 BCLIP: Bus Collision Interrupt Priority bit 1 = High priority 0 = Low priority bit 2 HLVDIP: High/Low-Voltage Detect Interrupt Priority bit 1 = High priority 0 = Low priority bit 1 TMR3IP: TMR3 Overflow Interrupt Priority bit 1 = High priority 0 = Low priority bit 0 CCP2IP: CCP2 Interrupt Priority bit 1 = High priority 0 = Low priority (c) 2008 Microchip Technology Inc. x = Bit is unknown DS39631E-page 101 PIC18F2420/2520/4420/4520 9.5 The operation of the SBOREN bit and the Reset flag bits is discussed in more detail in Section 4.1 "RCON Register". RCON Register The RCON register contains flag bits which are used to determine the cause of the last Reset or wake-up from Idle or Sleep modes. RCON also contains the IPEN bit which enables interrupt priorities. REGISTER 9-10: RCON: RESET CONTROL REGISTER R/W-0 R/W-1(1) U-0 R/W-1 R-1 R-1 R/W-0(1) R/W-0 IPEN SBOREN -- RI TO PD POR BOR 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 IPEN: Interrupt Priority Enable bit 1 = Enable priority levels on interrupts 0 = Disable priority levels on interrupts (PIC16CXXX Compatibility mode) bit 6 SBOREN: Software BOR Enable bit(1) For details of bit operation, see Register 4-1. bit 5 Unimplemented: Read as `0' bit 4 RI: RESET Instruction Flag bit For details of bit operation, see Register 4-1. bit 3 TO: Watchdog Timer Time-out Flag bit For details of bit operation, see Register 4-1. bit 2 PD: Power-Down Detection Flag bit For details of bit operation, see Register 4-1. bit 1 POR: Power-on Reset Status bit(1) For details of bit operation, see Register 4-1. bit 0 BOR: Brown-out Reset Status bit For details of bit operation, see Register 4-1. Note 1: Actual Reset values are determined by device configuration and the nature of the device Reset. See Register 4-1 for additional information. DS39631E-page 102 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 9.6 INTx Pin Interrupts 9.7 External interrupts on the RB0/INT0, RB1/INT1 and RB2/INT2 pins are edge-triggered. If the corresponding INTEDGx bit in the INTCON2 register is set (= 1), the interrupt is triggered by a rising edge; if the bit is clear, the trigger is on the falling edge. When a valid edge appears on the RBx/INTx pin, the corresponding flag bit, INTxIF, is set. This interrupt can be disabled by clearing the corresponding enable bit, INTxIE. Flag bit, INTxIF, must be cleared in software in the Interrupt Service Routine before re-enabling the interrupt. All external interrupts (INT0, INT1 and INT2) can wakeup the processor from Idle or Sleep modes if bit INTxIE was set prior to going into those modes. If the Global Interrupt Enable bit, GIE, is set, the processor will branch to the interrupt vector following wake-up. Interrupt priority for INT1 and INT2 is determined by the value contained in the Interrupt Priority bits, INT1IP (INTCON3<6>) and INT2IP (INTCON3<7>). There is no priority bit associated with INT0. It is always a high-priority interrupt source. TMR0 Interrupt In 8-bit mode (which is the default), an overflow in the TMR0 register (FFh 00h) will set flag bit, TMR0IF. In 16-bit mode, an overflow in the TMR0H:TMR0L register pair (FFFFh 0000h) will set TMR0IF. The interrupt can be enabled/disabled by setting/clearing enable bit, TMR0IE (INTCON<5>). Interrupt priority for Timer0 is determined by the value contained in the interrupt priority bit, TMR0IP (INTCON2<2>). See Section 11.0 "Timer0 Module" for further details on the Timer0 module. 9.8 PORTB Interrupt-on-Change An input change on PORTB<7:4> sets flag bit, RBIF (INTCON<0>). The interrupt can be enabled/disabled by setting/clearing enable bit, RBIE (INTCON<3>). Interrupt priority for PORTB interrupt-on-change is determined by the value contained in the interrupt priority bit, RBIP (INTCON2<0>). 9.9 Context Saving During Interrupts During interrupts, the return PC address is saved on the stack. Additionally, the WREG, STATUS and BSR registers are saved on the Fast Return Stack. If a fast return from interrupt is not used (see Section 5.3 "Data Memory Organization"), the user may need to save the WREG, STATUS and BSR registers on entry to the Interrupt Service Routine. Depending on the user's application, other registers may also need to be saved. Example 9-1 saves and restores the WREG, STATUS and BSR registers during an Interrupt Service Routine. EXAMPLE 9-1: MOVWF MOVFF MOVFF ; ; USER ; MOVFF MOVF MOVFF SAVING STATUS, WREG AND BSR REGISTERS IN RAM W_TEMP STATUS, STATUS_TEMP BSR, BSR_TEMP ; W_TEMP is in virtual bank ; STATUS_TEMP located anywhere ; BSR_TMEP located anywhere ISR CODE BSR_TEMP, BSR W_TEMP, W STATUS_TEMP, STATUS (c) 2008 Microchip Technology Inc. ; Restore BSR ; Restore WREG ; Restore STATUS DS39631E-page 103 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 104 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 10.0 I/O PORTS Depending on the device selected and features enabled, there are up to five ports available. Some pins of the I/O ports are multiplexed with an alternate function from the peripheral features on the device. In general, when a peripheral is enabled, that pin may not be used as a general purpose I/O pin. Each port has three registers for its operation. These registers are: * TRIS register (Data Direction register) * PORT register (reads the levels on the pins of the device) * LAT register (Data Latch register) The Data Latch (LAT register) is useful for read-modifywrite operations on the value that the I/O pins are driving. A simplified model of a generic I/O port, without the interfaces to other peripherals, is shown in Figure 10-1. FIGURE 10-1: Reading the PORTA register reads the status of the pins, whereas writing to it, will write to the port latch. The Data Latch (LATA) register is also memory mapped. Read-modify-write operations on the LATA register read and write the latched output value for PORTA. The RA4 pin is multiplexed with the Timer0 module clock input and one of the comparator outputs to become the RA4/T0CKI/C1OUT pin. Pins RA6 and RA7 are multiplexed with the main oscillator pins; they are enabled as oscillator or I/O pins by the selection of the main oscillator in the Configuration register (see Section 23.1 "Configuration Bits" for details). When they are not used as port pins, RA6 and RA7 and their associated TRIS and LAT bits are read as `0'. The other PORTA pins are multiplexed with analog inputs, the analog VREF+ and VREF- inputs and the comparator voltage reference output. The operation of pins RA<3:0> and RA5 as A/D Converter inputs is selected by clearing or setting the control bits in the ADCON1 register (A/D Control Register 1). Pins RA0 through RA5 may also be used as comparator inputs or outputs by setting the appropriate bits in the CMCON register. To use RA<3:0> as digital inputs, it is also necessary to turn off the comparators. GENERIC I/O PORT OPERATION RD LAT Note: Data Bus D WR LAT or Port Q I/O pin(1) CK Data Latch D WR TRIS Q CK TRIS Latch Input Buffer The RA4/T0CKI/C1OUT pin is a Schmitt Trigger input. All other PORTA pins have TTL input levels and full CMOS output drivers. The TRISA register controls the direction of the PORTA pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISA register are maintained set when using them as analog inputs. EXAMPLE 10-1: RD TRIS CLRF Q D CLRF ENEN RD Port Note 1: 10.1 On a Power-on Reset, RA5 and RA<3:0> are configured as analog inputs and read as `0'. RA4 is configured as a digital input. I/O pins have diode protection to VDD and VSS. MOVLW MOVWF MOVWF MOVWF MOVLW PORTA, TRISA and LATA Registers PORTA is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISA. Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., put the corresponding output driver in a high-impedance mode). Clearing a TRISA bit (= 0) will make the corresponding PORTA pin an output (i.e., put the contents of the output latch on the selected pin). (c) 2008 Microchip Technology Inc. MOVWF PORTA ; ; ; LATA ; ; ; 07h ; ADCON1 ; 07h ; CMCON ; 0CFh ; ; ; TRISA ; ; INITIALIZING PORTA Initialize PORTA by clearing output data latches Alternate method to clear output data latches Configure A/D for digital inputs Configure comparators for digital input Value used to initialize data direction Set RA<3:0> as inputs RA<5:4> as outputs DS39631E-page 105 PIC18F2420/2520/4420/4520 TABLE 10-1: PORTA I/O SUMMARY Pin RA0/AN0 RA1/AN1 RA2/AN2/ VREF-/CVREF RA3/AN3/VREF+ Function TRIS Setting I/O I/O Type RA0 0 O DIG 1 I TTL PORTA<0> data input; disabled when analog input enabled. AN0 1 I ANA A/D input channel 0 and comparator C1- input. Default input configuration on POR; does not affect digital output. RA1 0 O DIG LATA<1> data output; not affected by analog input. 1 I TTL PORTA<1> data input; disabled when analog input enabled. AN1 1 I ANA A/D input channel 1 and comparator C2- input. Default input configuration on POR; does not affect digital output. RA2 0 O DIG LATA<2> data output; not affected by analog input. Disabled when CVREF output enabled. 1 I TTL PORTA<2> data input. Disabled when analog functions enabled; disabled when CVREF output enabled. AN2 1 I ANA A/D input channel 2 and comparator C2+ input. Default input configuration on POR; not affected by analog output. VREF- 1 I ANA A/D and comparator voltage reference low input. CVREF x O ANA Comparator voltage reference output. Enabling this feature disables digital I/O. RA3 0 O DIG LATA<3> data output; not affected by analog input. 1 I TTL PORTA<3> data input; disabled when analog input enabled. 1 I ANA A/D input channel 3 and comparator C1+ input. Default input configuration on POR. AN3 RA4/T0CKI/C1OUT RA5/AN4/SS/ HLVDIN/C2OUT OSC2/CLKO/RA6 OSC1/CLKI/RA7 Legend: Description LATA<0> data output; not affected by analog input. VREF+ 1 I ANA A/D and comparator voltage reference high input. RA4 0 O DIG LATA<4> data output. 1 I ST PORTA<4> data input; default configuration on POR. T0CKI 1 I ST Timer0 clock input. C1OUT 0 O DIG Comparator 1 output; takes priority over port data. RA5 0 O DIG LATA<5> data output; not affected by analog input. 1 I TTL PORTA<5> data input; disabled when analog input enabled. A/D input channel 4. Default configuration on POR. AN4 1 I ANA SS 1 I TTL Slave select input for MSSP module. HLVDIN 1 I ANA High/Low-Voltage Detect external trip point input. C2OUT 0 O DIG Comparator 2 output; takes priority over port data. RA6 0 O DIG LATA<6> data output. Enabled in RCIO, INTIO2 and ECIO modes only. 1 I TTL PORTA<6> data input. Enabled in RCIO, INTIO2 and ECIO modes only. OSC2 x O ANA Main oscillator feedback output connection (XT, HS and LP modes). CLKO x O DIG System cycle clock output (FOSC/4) in RC, INTIO1 and EC Oscillator modes. RA7 0 O DIG LATA<7> data output. Disabled in external oscillator modes. 1 I TTL PORTA<7> data input. Disabled in external oscillator modes. OSC1 x I ANA Main oscillator input connection. CLKI x I ANA Main clock input connection. DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). DS39631E-page 106 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 10-2: Name PORTA SUMMARY OF REGISTERS ASSOCIATED WITH PORTA Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RA7(1) RA6(1) RA5 RA4 RA3 RA2 RA1 RA0 LATA LATA7(1) LATA6(1) PORTA Data Latch Register (Read and Write to Data Latch) TRISA TRISA7(1) TRISA6(1) PORTA Data Direction Register Reset Values on page 52 52 52 ADCON1 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 51 CMCON C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51 CVRCON CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTA. Note 1: RA<7:6> and their associated latch and data direction bits are enabled as I/O pins based on oscillator configuration; otherwise, they are read as `0'. (c) 2008 Microchip Technology Inc. DS39631E-page 107 PIC18F2420/2520/4420/4520 10.2 PORTB, TRISB and LATB Registers PORTB is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISB. Setting a TRISB bit (= 1) will make the corresponding PORTB pin an input (i.e., put the corresponding output driver in a high-impedance mode). Clearing a TRISB bit (= 0) will make the corresponding PORTB pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATB) is also memory mapped. Read-modify-write operations on the LATB register read and write the latched output value for PORTB. EXAMPLE 10-2: CLRF CLRF MOVLW MOVWF MOVLW MOVWF PORTB ; ; ; LATB ; ; ; 0Fh ; ADCON1 ; ; ; 0CFh ; ; ; TRISB ; ; ; INITIALIZING PORTB Initialize PORTB by clearing output data latches Alternate method to clear output data latches Set RB<4:0> as digital I/O pins (required if config bit PBADEN is set) Value used to initialize data direction Set RB<3:0> as inputs RB<5:4> as outputs RB<7:6> as inputs Four of the PORTB pins (RB<7:4>) have an interrupton-change feature. Only pins configured as inputs can cause this interrupt to occur (i.e., any RB<7:4> pin configured as an output is excluded from the interrupton-change comparison). The input pins (of RB<7:4>) are compared with the old value latched on the last read of PORTB. The "mismatch" outputs of RB<7:4> are ORed together to generate the RB Port Change Interrupt with Flag bit, RBIF (INTCON<0>). This interrupt can wake the device from the Sleep mode, or any of the Idle modes. The user, in the Interrupt Service Routine, can clear the interrupt in the following manner: a) b) Any read or write of PORTB (except with the MOVFF (ANY), PORTB instruction). Clear flag bit, RBIF. A mismatch condition will continue to set flag bit, RBIF. Reading PORTB will end the mismatch condition and allow flag bit, RBIF, to be cleared. The interrupt-on-change feature is recommended for wake-up on key depression operation and operations where PORTB is only used for the interrupt-on-change feature. Polling of PORTB is not recommended while using the interrupt-on-change feature. RB3 can be configured by the Configuration bit, CCP2MX, as the alternate peripheral pin for the CCP2 module (CCP2MX = 0). Each of the PORTB pins has a weak internal pull-up. A single control bit can turn on all the pull-ups. This is performed by clearing bit, RBPU (INTCON2<7>). The weak pull-up is automatically turned off when the port pin is configured as an output. The pull-ups are disabled on a Power-on Reset. Note: On a Power-on Reset, RB<4:0> are configured as analog inputs by default and read as `0'; RB<7:5> are configured as digital inputs. By programming the Configuration bit, PBADEN, RB<4:0> will alternatively be configured as digital inputs on POR. DS39631E-page 108 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 10-3: Pin RB0/INT0/FLT0/ AN12 RB1/INT1/AN10 RB2/INT2/AN8 RB3/AN9/CCP2 PORTB I/O SUMMARY Function TRIS Setting I/O I/O Type RB0 0 O DIG LATB<0> data output; not affected by analog input. 1 I TTL PORTB<0> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) External interrupt 0 input. INT0 1 I ST FLT0 1 I ST AN12 1 I ANA A/D input channel 12.(1) RB1 0 O DIG LATB<1> data output; not affected by analog input. 1 I TTL PORTB<1> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) INT1 1 I ST 1 I ANA A/D input channel 10.(1) RB2 0 O DIG LATB<2> data output; not affected by analog input. 1 I TTL PORTB<2> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) RB6/KBI2/PGC RB7/KBI3/PGD Legend: Note 1: 2: 3: External Interrupt 1 input. INT2 1 I ST AN8 1 I ANA A/D input channel 8.(1) RB3 0 O DIG LATB<3> data output; not affected by analog input. 1 I TTL PORTB<3> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) 1 I ANA A/D input channel 9.(1) 0 O DIG CCP2 compare and PWM output. 1 I ST CCP2 capture input 0 O DIG LATB<4> data output; not affected by analog input. 1 I TTL PORTB<4> data input; weak pull-up when RBPU bit is cleared. Disabled when analog input enabled.(1) KBI0 1 I TTL Interrupt-on-pin change. AN11 1 I ANA A/D input channel 11.(1) RB5 0 O DIG LATB<5> data output. 1 I TTL PORTB<5> data input; weak pull-up when RBPU bit is cleared. CCP2 RB5/KBI1/PGM Enhanced PWM Fault input (ECCP1 module); enabled in software. AN10 AN9 RB4/KBI0/AN11 Description (2) RB4 External interrupt 2 input. KBI1 1 I TTL Interrupt-on-pin change. PGM x I ST Single-Supply In-Circuit Serial ProgrammingTM mode entry (ICSPTM). Enabled by LVP Configuration bit; all other pin functions disabled. RB6 0 O DIG LATB<6> data output. 1 I TTL PORTB<6> data input; weak pull-up when RBPU bit is cleared. KBI2 1 I TTL Interrupt-on-pin change. PGC x I ST Serial execution (ICSP) clock input for ICSP and ICD operation.(3) RB7 0 O DIG LATB<7> data output. 1 I TTL PORTB<7> data input; weak pull-up when RBPU bit is cleared. KBI3 1 I TTL Interrupt-on-pin change. PGD x O DIG Serial execution data output for ICSP and ICD operation.(3) x I ST Serial execution data input for ICSP and ICD operation.(3) DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). Configuration on POR is determined by the PBADEN Configuration bit. Pins are configured as analog inputs by default when PBADEN is set and digital inputs when PBADEN is cleared. Alternate assignment for CCP2 when the CCP2MX Configuration bit is `0'. Default assignment is RC1. All other pin functions are disabled when ICSP or ICD are enabled. (c) 2008 Microchip Technology Inc. DS39631E-page 109 PIC18F2420/2520/4420/4520 TABLE 10-4: Name PORTB SUMMARY OF REGISTERS ASSOCIATED WITH PORTB Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0 LATB PORTB Data Latch Register (Read and Write to Data Latch) TRISB PORTB Data Direction Register INTCON GIE/GIEH PEIE/GIEL TMR0IE Reset Values on page 52 52 52 INT0IE INTEDG0 INTEDG1 INTEDG2 RBIE TMR0IF INT0IF RBIF 49 INTCON2 RBPU -- TMR0IP -- RBIP 49 INTCON3 INT2IP INT1IP -- INT2IE INT1IE -- INT2IF INT1IF 49 ADCON1 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTB. DS39631E-page 110 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 10.3 PORTC, TRISC and LATC Registers PORTC is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISC. Setting a TRISC bit (= 1) will make the corresponding PORTC pin an input (i.e., put the corresponding output driver in a high-impedance mode). Clearing a TRISC bit (= 0) will make the corresponding PORTC pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATC) is also memory mapped. Read-modify-write operations on the LATC register read and write the latched output value for PORTC. PORTC is multiplexed with several peripheral functions (Table 10-5). The pins have Schmitt Trigger input buffers. RC1 is normally configured by Configuration bit, CCP2MX, as the default peripheral pin of the CCP2 module (default/erased state, CCP2MX = 1). When enabling peripheral functions, care should be taken in defining TRIS bits for each PORTC pin. Some peripherals override the TRIS bit to make a pin an output, while other peripherals override the TRIS bit to make a pin an input. The user should refer to the corresponding peripheral section for additional information. (c) 2008 Microchip Technology Inc. Note: On a Power-on Reset, these pins are configured as digital inputs. The contents of the TRISC register are affected by peripheral overrides. Reading TRISC always returns the current contents, even though a peripheral device may be overriding one or more of the pins. EXAMPLE 10-3: CLRF PORTC CLRF LATC MOVLW 0CFh MOVWF TRISC INITIALIZING PORTC ; ; ; ; ; ; ; ; ; ; ; ; Initialize PORTC by clearing output data latches Alternate method to clear output data latches Value used to initialize data direction Set RC<3:0> as inputs RC<5:4> as outputs RC<7:6> as inputs DS39631E-page 111 PIC18F2420/2520/4420/4520 TABLE 10-5: Pin PORTC I/O SUMMARY Function TRIS Setting I/O I/O Type RC0 0 O DIG RC0/T1OSO/ T13CKI RC1/T1OSI/CCP2 RC2/CCP1/P1A 1 I ST x O ANA T13CKI 1 I ST Timer1/Timer3 counter input. RC1 0 O DIG LATC<1> data output. 1 I ST T1OSI x I ANA Timer1 oscillator input; enabled when Timer1 oscillator enabled. Disables digital I/O. CCP2(1) 0 O DIG CCP2 compare and PWM output; takes priority over port data. 1 I ST CCP2 capture input. 0 O DIG LATC<2> data output. 1 I ST PORTC<2> data input. 0 O DIG ECCP1 compare or PWM output; takes priority over port data. 1 I ST ECCP1 capture input. P1A(2) 0 O DIG ECCP1 Enhanced PWM output, channel A. May be configured for tri-state during Enhanced PWM shutdown events. Takes priority over port data. RC3 0 O DIG LATC<3> data output. 1 I ST PORTC<3> data input. 0 O DIG SPI clock output (MSSP module); takes priority over port data. RC2 SCK SCL RC4/SDI/SDA RC5/SDO RC7/RX/DT Legend: Note 1: 2: RC4 PORTC<0> data input. Timer1 oscillator output; enabled when Timer1 oscillator enabled. Disables digital I/O. PORTC<1> data input. 1 I ST SPI clock input (MSSP module). 0 O DIG I2CTM clock output (MSSP module); takes priority over port data. 1 I I2C/SMB 0 O DIG I2C clock input (MSSP module); input type depends on module setting. LATC<4> data output. 1 I ST PORTC<4> data input. SDI 1 I ST SPI data input (MSSP module). SDA 1 O DIG I2C data output (MSSP module); takes priority over port data. 1 I 0 O DIG 1 I ST PORTC<5> data input. SDO 0 O DIG SPI data output (MSSP module); takes priority over port data. RC6 0 O DIG LATC<6> data output. RC5 RC6/TX/CK LATC<0> data output. T1OSO CCP1 RC3/SCK/SCL Description I2C/SMB I2C data input (MSSP module); input type depends on module setting. LATC<5> data output. 1 I ST PORTC<6> data input. TX 1 O DIG Asynchronous serial transmit data output (EUSART module); takes priority over port data. User must configure as output. CK 1 O DIG Synchronous serial clock output (EUSART module); takes priority over port data. 1 I ST Synchronous serial clock input (EUSART module). 0 O DIG LATC<7> data output. 1 I ST PORTC<7> data input. RX 1 I ST Asynchronous serial receive data input (EUSART module). DT 1 O DIG Synchronous serial data output (EUSART module); takes priority over port data. 1 I ST Synchronous serial data input (EUSART module). User must configure as an input. RC7 DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; I2C/SMB = I2C/SMBus input buffer; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). Default assignment for CCP2 when the CCP2MX Configuration bit is set. Alternate assignment is RB3. Enhanced PWM output is available only on PIC18F4520 devices. DS39631E-page 112 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 10-6: Name PORTC SUMMARY OF REGISTERS ASSOCIATED WITH PORTC Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 Reset Values on page 52 LATC PORTC Data Latch Register (Read and Write to Data Latch) 52 TRISC PORTC Data Direction Register 52 (c) 2008 Microchip Technology Inc. DS39631E-page 113 PIC18F2420/2520/4420/4520 10.4 Note: PORTD, TRISD and LATD Registers PORTD is only available on 40/44-pin devices. PORTD is an 8-bit wide, bidirectional port. The corresponding Data Direction register is TRISD. Setting a TRISD bit (= 1) will make the corresponding PORTD pin an input (i.e., put the corresponding output driver in a high-impedance mode). Clearing a TRISD bit (= 0) will make the corresponding PORTD pin an output (i.e., put the contents of the output latch on the selected pin). The Data Latch register (LATD) is also memory mapped. Read-modify-write operations on the LATD register read and write the latched output value for PORTD. All pins on PORTD are implemented with Schmitt Trigger input buffers. Each pin is individually configurable as an input or output. Three of the PORTD pins are multiplexed with outputs P1B, P1C and P1D of the Enhanced CCP module. The operation of these additional PWM output pins is covered in greater detail in Section 16.0 "Enhanced Capture/Compare/PWM (ECCP) Module". Note: PORTD can also be configured as an 8-bit wide microprocessor port (Parallel Slave Port) by setting control bit, PSPMODE (TRISE<4>). In this mode, the input buffers are TTL. See Section 10.6 "Parallel Slave Port" for additional information on the Parallel Slave Port (PSP). Note: When the enhanced PWM mode is used with either dual or quad outputs, the PSP functions of PORTD are automatically disabled. EXAMPLE 10-4: CLRF PORTD CLRF LATD MOVLW 0CFh MOVWF TRISD INITIALIZING PORTD ; ; ; ; ; ; ; ; ; ; ; ; Initialize PORTD by clearing output data latches Alternate method to clear output data latches Value used to initialize data direction Set RD<3:0> as inputs RD<5:4> as outputs RD<7:6> as inputs On a Power-on Reset, these pins are configured as digital inputs. DS39631E-page 114 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 10-7: Pin RD0/PSP0 RD1/PSP1 RD2/PSP2 RD3/PSP3 RD4/PSP4 RD5/PSP5/P1B RD6/PSP6/P1C PORTD I/O SUMMARY Function TRIS Setting I/O I/O Type RD0 0 O DIG 1 I ST PORTD<0> data input. PSP0 x O DIG PSP read data output (LATD<0>); takes priority over port data. Legend: LATD<0> data output. x I TTL PSP write data input. RD1 0 O DIG LATD<1> data output. 1 I ST PORTD<1> data input. PSP1 x O DIG PSP read data output (LATD<1>); takes priority over port data. x I TTL PSP write data input. RD2 0 O DIG LATD<2> data output. 1 I ST PORTD<2> data input. PSP2 x O DIG PSP read data output (LATD<2>); takes priority over port data. x I TTL PSP write data input. RD3 0 O DIG LATD<3> data output. 1 I ST PORTD<3> data input. PSP3 x O DIG PSP read data output (LATD<3>); takes priority over port data. x I TTL PSP write data input. RD4 0 O DIG LATD<4> data output. 1 I ST PORTD<4> data input. PSP4 x O DIG PSP read data output (LATD<4>); takes priority over port data. x I TTL PSP write data input. RD5 0 O DIG LATD<5> data output. 1 I ST PORTD<5> data input. PSP5 x O DIG PSP read data output (LATD<5>); takes priority over port data. x I TTL PSP write data input. P1B 0 O DIG ECCP1 Enhanced PWM output, channel B; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. RD6 0 O DIG LATD<6> data output. 1 I ST PORTD<6> data input. x O DIG PSP read data output (LATD<6>); takes priority over port data. x I TTL PSP write data input. P1C 0 O DIG ECCP1 Enhanced PWM output, channel C; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. RD7 0 O DIG LATD<7> data output. 1 I ST PORTD<7> data input. PSP7 x O DIG PSP read data output (LATD<7>); takes priority over port data. x I TTL PSP write data input. P1D 0 O DIG ECCP1 Enhanced PWM output, channel D; takes priority over port and PSP data. May be configured for tri-state during Enhanced PWM shutdown events. PSP6 RD7/PSP7/P1D Description DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). (c) 2008 Microchip Technology Inc. DS39631E-page 115 PIC18F2420/2520/4420/4520 TABLE 10-8: Name PORTD LATD TRISD (1) TRISE CCP1CON SUMMARY OF REGISTERS ASSOCIATED WITH PORTD Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 Reset Values on page 52 PORTD Data Latch Register (Read and Write to Data Latch) 52 PORTD Data Direction Register 52 IBF OBF IBOV PSPMODE -- TRISE2 TRISE1 TRISE0 52 P1M1(1) P1M0(1) DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTD. Note 1: These registers and/or bits are unimplemented on 28-oin devices. DS39631E-page 116 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 10.5 PORTE, TRISE and LATE Registers Depending on the particular PIC18F2420/2520/4420/ 4520 device selected, PORTE is implemented in two different ways. For 40/44-pin devices, PORTE is a 4-bit wide port. Three pins (RE0/RD/AN5, RE1/WR/AN6 and RE2/CS/ AN7) are individually configurable as inputs or outputs. These pins have Schmitt Trigger input buffers. When selected as an analog input, these pins will read as `0's. The corresponding Data Direction register is TRISE. Setting a TRISE bit (= 1) will make the corresponding PORTE pin an input (i.e., put the corresponding output driver in a high-impedance mode). Clearing a TRISE bit (= 0) will make the corresponding PORTE pin an output (i.e., put the contents of the output latch on the selected pin). TRISE controls the direction of the RE pins, even when they are being used as analog inputs. The user must make sure to keep the pins configured as inputs when using them as analog inputs. Note: On a Power-on Reset, RE<2:0> are configured as analog inputs. The upper four bits of the TRISE register also control the operation of the Parallel Slave Port. Their operation is explained in Register 10-1. The Data Latch register (LATE) is also memory mapped. Read-modify-write operations on the LATE register, read and write the latched output value for PORTE. (c) 2008 Microchip Technology Inc. The fourth pin of PORTE (MCLR/VPP/RE3) is an input only pin. Its operation is controlled by the MCLRE Configuration bit. When selected as a port pin (MCLRE = 0), it functions as a digital input only pin; as such, it does not have TRIS or LAT bits associated with its operation. Otherwise, it functions as the device's Master Clear input. In either configuration, RE3 also functions as the programming voltage input during programming. Note: On a Power-on Reset, RE3 is enabled as a digital input only if Master Clear functionality is disabled. EXAMPLE 10-5: CLRF CLRF MOVLW MOVWF MOVLW MOVWF 10.5.1 PORTE ; ; ; LATE ; ; ; 0Ah ; ADCON1 ; 03h ; ; ; TRISE ; ; ; INITIALIZING PORTE Initialize PORTE by clearing output data latches Alternate method to clear output data latches Configure A/D for digital inputs Value used to initialize data direction Set RE<0> as inputs RE<1> as outputs RE<2> as inputs PORTE IN 28-PIN DEVICES For 28-pin devices, PORTE is only available when Master Clear functionality is disabled (MCLRE = 0). In these cases, PORTE is a single bit, input only port comprised of RE3 only. The pin operates as previously described. DS39631E-page 117 PIC18F2420/2520/4420/4520 REGISTER 10-1: R-0 TRISE REGISTER (40/44-PIN DEVICES ONLY) R-0 IBF OBF R/W-0 IBOV R/W-0 U-0 R/W-1 R/W-1 R/W-1 PSPMODE -- TRISE2 TRISE1 TRISE0 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 IBF: Input Buffer Full Status bit 1 = A word has been received and waiting to be read by the CPU 0 = No word has been received bit 6 OBF: Output Buffer Full Status bit 1 = The output buffer still holds a previously written word 0 = The output buffer has been read bit 5 IBOV: Input Buffer Overflow Detect bit (in Microprocessor mode) 1 = A write occurred when a previously input word has not been read (must be cleared in software) 0 = No overflow occurred bit 4 PSPMODE: Parallel Slave Port Mode Select bit 1 = Parallel Slave Port mode 0 = General purpose I/O mode bit 3 Unimplemented: Read as `0' bit 2 TRISE2: RE2 Direction Control bit 1 = Input 0 = Output bit 1 TRISE1: RE1 Direction Control bit 1 = Input 0 = Output bit 0 TRISE0: RE0 Direction Control bit 1 = Input 0 = Output DS39631E-page 118 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 10-9: PORTE I/O SUMMARY Pin Function TRIS Setting I/O I/O Type RE0 0 O DIG LATE<0> data output; not affected by analog input. 1 I ST PORTE<0> data input; disabled when analog input enabled. RE0/RD/AN5 RE1/WR/AN6 RE2/CS/AN7 MCLR/VPP/RE3(1) Legend: Note 1: 2: Description RD 1 I TTL PSP read enable input (PSP enabled). AN5 1 I ANA A/D input channel 5; default input configuration on POR. RE1 0 O DIG LATE<1> data output; not affected by analog input. 1 I ST PORTE<1> data input; disabled when analog input enabled. WR 1 I TTL PSP write enable input (PSP enabled). AN6 1 I ANA A/D input channel 6; default input configuration on POR. RE2 0 O DIG LATE<2> data output; not affected by analog input. 1 I ST PORTE<2> data input; disabled when analog input enabled. CS 1 I TTL PSP write enable input (PSP enabled). AN7 1 I ANA A/D input channel 7; default input configuration on POR. MCLR -- I ST External Master Clear input; enabled when MCLRE Configuration bit is set. VPP -- I ANA High-voltage detection; used for ICSPTM mode entry detection. Always available regardless of pin mode. RE3 --(2) I ST PORTE<3> data input; enabled when MCLRE Configuration bit is clear. DIG = Digital level output; TTL = TTL input buffer; ST = Schmitt Trigger input buffer; ANA = Analog level input/output; x = Don't care (TRIS bit does not affect port direction or is overridden for this option). RE3 is available on both 28-pin and 40/44-pin devices. All other PORTE pins are only implemented on 40/44-pin devices. RE3 does not have a corresponding TRIS bit to control data direction. TABLE 10-10: SUMMARY OF REGISTERS ASSOCIATED WITH PORTE Name Bit 2 Bit 1 Bit 0 RE2 RE1 RE0 Reset Values on page Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 PORTE -- -- -- -- RE3(1,2) LATE(2) -- -- -- -- -- TRISE IBF OBF IBOV PSPMODE -- TRISE2 TRISE1 TRISE0 52 ADCON1 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 51 LATE Data Latch Register 52 52 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PORTE. Note 1: Implemented only when Master Clear functionality is disabled (MCLRE Configuration bit = 0). 2: RE3 is the only PORTE bit implemented on both 28-pin and 40/44-pin devices. All other bits are implemented only when PORTE is implemented (i.e., 40/44-pin devices). (c) 2008 Microchip Technology Inc. DS39631E-page 119 PIC18F2420/2520/4420/4520 10.6 Note: Parallel Slave Port The Parallel Slave Port is only available on 40/44-pin devices. In addition to its function as a general I/O port, PORTD can also operate as an 8-bit wide Parallel Slave Port (PSP) or microprocessor port. PSP operation is controlled by the 4 upper bits of the TRISE register (Register 10-1). Setting control bit, PSPMODE (TRISE<4>), enables PSP operation as long as the Enhanced CCP module is not operating in dual output or quad output PWM mode. In Slave mode, the port is asynchronously readable and writable by the external world. The PSP can directly interface to an 8-bit microprocessor data bus. The external microprocessor can read or write the PORTD latch as an 8-bit latch. Setting the control bit, PSPMODE, enables the PORTE I/O pins to become control inputs for the microprocessor port. When set, port pin RE0 is the RD input, RE1 is the WR input and RE2 is the CS (Chip Select) input. For this functionality, the corresponding data direction bits of the TRISE register (TRISE<2:0>) must be configured as inputs (set). The A/D port configuration bits, PFCG<3:0> (ADCON1<3:0>), must also be set to a value in the range of `1010' through `1111'. The timing for the control signals in Write and Read modes is shown in Figure 10-3 and Figure 10-4, respectively. FIGURE 10-2: One bit of PORTD Data Bus WR LATD or WR PORTD Q RDx pin CK Data Latch RD PORTD TTL D ENEN RD LATD Set Interrupt Flag PSPIF (PIR1<7>) PORTE Pins Read A read from the PSP occurs when both the CS and RD lines are first detected low. The data in PORTD is read out and the OBF bit is clear. If the user writes new data to PORTD to set OBF, the data is immediately read out; however, the OBF bit is not set. DS39631E-page 120 D Q A write to the PSP occurs when both the CS and WR lines are first detected low and ends when either are detected high. The PSPIF and IBF flag bits are both set when the write ends. When either the CS or RD lines are detected high, the PORTD pins return to the input state and the PSPIF bit is set. User applications should wait for PSPIF to be set before servicing the PSP; when this happens, the IBF and OBF bits can be polled and the appropriate action taken. PORTD AND PORTE BLOCK DIAGRAM (PARALLEL SLAVE PORT) TTL RD Chip Select TTL CS Write Note: TTL WR I/O pins have diode protection to VDD and VSS. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 10-3: PARALLEL SLAVE PORT WRITE WAVEFORMS Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q4 Q1 Q2 Q3 Q4 CS WR RD PORTD<7:0> IBF OBF PSPIF FIGURE 10-4: PARALLEL SLAVE PORT READ WAVEFORMS Q1 Q2 Q3 Q4 Q1 Q2 Q3 CS WR RD PORTD<7:0> IBF OBF PSPIF TABLE 10-11: REGISTERS ASSOCIATED WITH PARALLEL SLAVE PORT Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page PORTD RD7 RD6 RD5 RD4 RD3 RD2 RD1 RD0 52 LATD PORTD Data Latch Register (Read and Write to Data Latch) 52 TRISD PORTD Data Direction Register 52 PORTE -- -- -- -- RE3 LATE -- -- -- -- -- IBF OBF IBOV PSPMODE -- TRISE2 TRISE1 TRISE0 52 TMR0IF INT0IE RBIE TMR0IF INT0IF RBIF 49 TRISE INTCON GIE/GIEH PEIE/GIEL RE2 RE1 RE0 LATE Data Latch Register 52 52 PIR1 PSPIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 51 ADCON1 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Parallel Slave Port. (c) 2008 Microchip Technology Inc. DS39631E-page 121 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 122 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 11.0 TIMER0 MODULE The Timer0 module incorporates the following features: * Software selectable operation as a timer or counter in both 8-bit or 16-bit modes * Readable and writable registers * Dedicated 8-bit, software programmable prescaler * Selectable clock source (internal or external) * Edge select for external clock * Interrupt-on-overflow REGISTER 11-1: The T0CON register (Register 11-1) controls all aspects of the module's operation, including the prescale selection. It is both readable and writable. A simplified block diagram of the Timer0 module in 8-bit mode is shown in Figure 11-1. Figure 11-2 shows a simplified block diagram of the Timer0 module in 16-bit mode. T0CON: TIMER0 CONTROL REGISTER R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 TMR0ON T08BIT T0CS T0SE PSA T0PS2 T0PS1 T0PS0 bit 7 bit 0 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 TMR0ON: Timer0 On/Off Control bit 1 = Enables Timer0 0 = Stops Timer0 bit 6 T08BIT: Timer0 8-Bit/16-Bit Control bit 1 = Timer0 is configured as an 8-bit timer/counter 0 = Timer0 is configured as a 16-bit timer/counter bit 5 T0CS: Timer0 Clock Source Select bit 1 = Transition on T0CKI pin 0 = Internal instruction cycle clock (CLKO) bit 4 T0SE: Timer0 Source Edge Select bit 1 = Increment on high-to-low transition on T0CKI pin 0 = Increment on low-to-high transition on T0CKI pin bit 3 PSA: Timer0 Prescaler Assignment bit 1 = TImer0 prescaler is not assigned. Timer0 clock input bypasses prescaler. 0 = Timer0 prescaler is assigned. Timer0 clock input comes from prescaler output. bit 2-0 T0PS<2:0>: Timer0 Prescaler Select bits 111 = 1:256 Prescale value 110 = 1:128 Prescale value 101 = 1:64 Prescale value 100 = 1:32 Prescale value 011 = 1:16 Prescale value 010 = 1:8 Prescale value 001 = 1:4 Prescale value 000 = 1:2 Prescale value (c) 2008 Microchip Technology Inc. DS39631E-page 123 PIC18F2420/2520/4420/4520 11.1 Timer0 Operation Timer0 can operate as either a timer or a counter; the mode is selected with the T0CS bit (T0CON<5>). In Timer mode (T0CS = 0), the module increments on every clock by default unless a different prescaler value is selected (see Section 11.3 "Prescaler"). If the TMR0 register is written to, the increment is inhibited for the following two instruction cycles. The user can work around this by writing an adjusted value to the TMR0 register. The Counter mode is selected by setting the T0CS bit (= 1). In this mode, Timer0 increments either on every rising or falling edge of pin RA4/T0CKI. The incrementing edge is determined by the Timer0 Source Edge Select bit, T0SE (T0CON<4>); clearing this bit selects the rising edge. Restrictions on the external clock input are discussed below. An external clock source can be used to drive Timer0; however, it must meet certain requirements to ensure that the external clock can be synchronized with the FIGURE 11-1: internal phase clock (TOSC). There is a delay between synchronization and the onset of incrementing the timer/counter. 11.2 Timer0 Reads and Writes in 16-Bit Mode TMR0H is not the actual high byte of Timer0 in 16-bit mode; it is actually a buffered version of the real high byte of Timer0 which is not directly readable nor writable (refer to Figure 11-2). TMR0H is updated with the contents of the high byte of Timer0 during a read of TMR0L. This provides the ability to read all 16 bits of Timer0 without having to verify that the read of the high and low byte were valid, due to a rollover between successive reads of the high and low byte. Similarly, a write to the high byte of Timer0 must also take place through the TMR0H Buffer register. The high byte is updated with the contents of TMR0H when a write occurs to TMR0L. This allows all 16 bits of Timer0 to be updated at once. TIMER0 BLOCK DIAGRAM (8-BIT MODE) FOSC/4 0 0 1 Programmable Prescaler T0CKI pin T0SE T0CS 1 Sync with Internal Clocks (2 TCY Delay) 8 3 T0PS<2:0> 8 PSA Note: Set TMR0IF on Overflow TMR0L Internal Data Bus Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale. FIGURE 11-2: FOSC/4 TIMER0 BLOCK DIAGRAM (16-BIT MODE) 0 0 1 T0CKI pin T0SE T0CS Programmable Prescaler 1 Sync with Internal Clocks TMR0 High Byte TMR0L 8 Set TMR0IF on Overflow (2 TCY Delay) 3 Read TMR0L T0PS<2:0> Write TMR0L PSA 8 8 TMR0H 8 8 Internal Data Bus Note: Upon Reset, Timer0 is enabled in 8-bit mode with clock input from T0CKI max. prescale. DS39631E-page 124 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 11.3 11.3.1 Prescaler An 8-bit counter is available as a prescaler for the Timer0 module. The prescaler is not directly readable or writable; its value is set by the PSA and T0PS<2:0> bits (T0CON<3:0>) which determine the prescaler assignment and prescale ratio. Clearing the PSA bit assigns the prescaler to the Timer0 module. When it is assigned, prescale values from 1:2 through 1:256 in power-of-2 increments are selectable. When assigned to the Timer0 module, all instructions writing to the TMR0 register (e.g., CLRF TMR0, MOVWF TMR0, BSF TMR0, etc.) clear the prescaler count. Note: Writing to TMR0 when the prescaler is assigned to Timer0 will clear the prescaler count but will not change the prescaler assignment. TABLE 11-1: Name SWITCHING PRESCALER ASSIGNMENT The prescaler assignment is fully under software control and can be changed "on-the-fly" during program execution. 11.4 Timer0 Interrupt The TMR0 interrupt is generated when the TMR0 register overflows from FFh to 00h in 8-bit mode, or from FFFFh to 0000h in 16-bit mode. This overflow sets the TMR0IF flag bit. The interrupt can be masked by clearing the TMR0IE bit (INTCON<5>). Before reenabling the interrupt, the TMR0IF bit must be cleared in software by the Interrupt Service Routine. Since Timer0 is shut down in Sleep mode, the TMR0 interrupt cannot awaken the processor from Sleep. REGISTERS ASSOCIATED WITH TIMER0 Bit 7 Bit 6 Bit 5 TMR0L Timer0 Register Low Byte TMR0H Timer0 Register High Byte INTCON GIE/GIEH PEIE/GIEL TMR0IE T0CON TMR0ON T08BIT TRISA RA7(1) RA6(1) Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page 50 50 INT0IE RBIE TMR0IF INT0IF RBIF 49 T0CS T0SE PSA T0PS2 T0PS1 T0PS0 50 RA5 RA4 RA3 RA2 RA1 RA0 52 Legend: Shaded cells are not used by Timer0. Note 1: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. (c) 2008 Microchip Technology Inc. DS39631E-page 125 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 126 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 12.0 TIMER1 MODULE The Timer1 timer/counter module incorporates these features: * Software selectable operation as a 16-bit timer or counter * Readable and writable 8-bit registers (TMR1H and TMR1L) * Selectable clock source (internal or external) with device clock or Timer1 oscillator internal options * Interrupt-on-overflow * Reset on CCP Special Event Trigger * Device clock status flag (T1RUN) REGISTER 12-1: A simplified block diagram of the Timer1 module is shown in Figure 12-1. A block diagram of the module's operation in Read/Write mode is shown in Figure 12-2. The module incorporates its own low-power oscillator to provide an additional clocking option. The Timer1 oscillator can also be used as a low-power clock source for the microcontroller in power-managed operation. Timer1 can also be used to provide Real-Time Clock (RTC) functionality to applications with only a minimal addition of external components and code overhead. Timer1 is controlled through the T1CON Control register (Register 12-1). It also contains the Timer1 Oscillator Enable bit (T1OSCEN). Timer1 can be enabled or disabled by setting or clearing control bit, TMR1ON (T1CON<0>). T1CON: TIMER1 CONTROL REGISTER R/W-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON bit 7 bit 0 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 RD16: 16-Bit Read/Write Mode Enable bit 1 = Enables register read/write of TImer1 in one 16-bit operation 0 = Enables register read/write of Timer1 in two 8-bit operations bit 6 T1RUN: Timer1 System Clock Status bit 1 = Device clock is derived from Timer1 oscillator 0 = Device clock is derived from another source bit 5-4 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: Timer1 Oscillator Enable bit 1 = Timer1 oscillator is enabled 0 = Timer1 oscillator is shut off The oscillator inverter and feedback resistor are turned off to eliminate power drain. bit 2 T1SYNC: Timer1 External Clock Input Synchronization Select bit When TMR1CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input When TMR1CS = 0: This bit is ignored. Timer1 uses the internal clock when TMR1CS = 0. bit 1 TMR1CS: Timer1 Clock Source Select bit 1 = External clock from pin RC0/T1OSO/T13CKI (on the rising edge) 0 = Internal clock (FOSC/4) bit 0 TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 (c) 2008 Microchip Technology Inc. DS39631E-page 127 PIC18F2420/2520/4420/4520 12.1 cycle (FOSC/4). When the bit is set, Timer1 increments on every rising edge of the Timer1 external clock input or the Timer1 oscillator, if enabled. Timer1 Operation Timer1 can operate in one of these modes: * Timer * Synchronous Counter * Asynchronous Counter When Timer1 is enabled, the RC1/T1OSI and RC0/ T1OSO/T13CKI pins become inputs. This means the values of TRISC<1:0> are ignored and the pins are read as `0'. The operating mode is determined by the clock select bit, TMR1CS (T1CON<1>). When TMR1CS is cleared (= 0), Timer1 increments on every internal instruction FIGURE 12-1: TIMER1 BLOCK DIAGRAM Timer1 Oscillator Timer1 Clock Input On/Off T1OSO/T13CKI 1 1 FOSC/4 Internal Clock T1OSI Synchronize Prescaler 1, 2, 4, 8 0 Detect 0 2 T1OSCEN(1) Sleep Input TMR1CS Timer1 On/Off T1CKPS<1:0> T1SYNC TMR1ON Clear TMR1 (CCP Special Event Trigger) Set TMR1IF on Overflow TMR1 High Byte TMR1L Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain. FIGURE 12-2: TIMER1 BLOCK DIAGRAM (16-BIT READ/WRITE MODE) Timer1 Clock Input Timer1 Oscillator 1 T1OSO/T13CKI 1 FOSC/4 Internal Clock T1OSI Synchronize Prescaler 1, 2, 4, 8 0 Detect 0 2 T1OSCEN(1) T1CKPS<1:0> T1SYNC TMR1ON Sleep Input TMR1CS Clear TMR1 (CCP Special Event Trigger) Timer1 On/Off TMR1 High Byte TMR1L 8 Set TMR1IF on Overflow Read TMR1L Write TMR1L 8 8 TMR1H 8 8 Internal Data Bus Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain. DS39631E-page 128 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 12.2 Timer1 16-Bit Read/Write Mode Timer1 can be configured for 16-bit reads and writes (see Figure 12-2). When the RD16 control bit (T1CON<7>) is set, the address for TMR1H is mapped to a buffer register for the high byte of Timer1. A read from TMR1L will load the contents of the high byte of Timer1 into the Timer1 high byte buffer. This provides the user with the ability to accurately read all 16 bits of Timer1 without having to determine whether a read of the high byte, followed by a read of the low byte, has become invalid due to a rollover between reads. TABLE 12-1: Osc Type LP CAPACITOR SELECTION FOR THE TIMER OSCILLATOR Freq 32 kHz C1 27 pF C2 (1) 27 pF(1) Note 1: Microchip suggests these values as a starting point in validating the oscillator circuit. 2: Higher capacitance increases the stability of the oscillator but also increases the start-up time. A write to the high byte of Timer1 must also take place through the TMR1H Buffer register. The Timer1 high byte is updated with the contents of TMR1H when a write occurs to TMR1L. This allows a user to write all 16 bits to both the high and low bytes of Timer1 at once. 3: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. The high byte of Timer1 is not directly readable or writable in this mode. All reads and writes must take place through the Timer1 High Byte Buffer register. Writes to TMR1H do not clear the Timer1 prescaler. The prescaler is only cleared on writes to TMR1L. 4: Capacitor values are for design guidance only. 12.3 Timer1 Oscillator An on-chip crystal oscillator circuit is incorporated between pins T1OSI (input) and T1OSO (amplifier output). It is enabled by setting the Timer1 Oscillator Enable bit, T1OSCEN (T1CON<3>). The oscillator is a lowpower circuit rated for 32 kHz crystals. It will continue to run during all power-managed modes. The circuit for a typical LP oscillator is shown in Figure 12-3. Table 12-1 shows the capacitor selection for the Timer1 oscillator. The user must provide a software time delay to ensure proper start-up of the Timer1 oscillator. FIGURE 12-3: EXTERNAL COMPONENTS FOR THE TIMER1 LP OSCILLATOR C1 27 pF PIC18FXXXX T1OSI XTAL 32.768 kHz T1OSO C2 27 pF Note: See the Notes with Table 12-1 for additional information about capacitor selection. 12.3.1 USING TIMER1 AS A CLOCK SOURCE The Timer1 oscillator is also available as a clock source in power-managed modes. By setting the clock select bits, SCS<1:0> (OSCCON<1:0>), to `01', the device switches to SEC_RUN mode; both the CPU and peripherals are clocked from the Timer1 oscillator. If the IDLEN bit (OSCCON<7>) is cleared and a SLEEP instruction is executed, the device enters SEC_IDLE mode. Additional details are available in Section 3.0 "Power-Managed Modes". Whenever the Timer1 oscillator is providing the clock source, the Timer1 system clock status flag, T1RUN (T1CON<6>), is set. This can be used to determine the controller's current clocking mode. It can also indicate the clock source being currently used by the Fail-Safe Clock Monitor. If the Clock Monitor is enabled and the Timer1 oscillator fails while providing the clock, polling the T1RUN bit will indicate whether the clock is being provided by the Timer1 oscillator or another source. 12.3.2 LOW-POWER TIMER1 OPTION The Timer1 oscillator can operate at two distinct levels of power consumption based on device configuration. When the LPT1OSC Configuration bit is set, the Timer1 oscillator operates in a low-power mode. When LPT1OSC is not set, Timer1 operates at a higher power level. Power consumption for a particular mode is relatively constant, regardless of the device's operating mode. The default Timer1 configuration is the higher power mode. As the low-power Timer1 mode tends to be more sensitive to interference, high noise environments may cause some oscillator instability. The low-power option is, therefore, best suited for low noise applications where power conservation is an important design consideration. (c) 2008 Microchip Technology Inc. DS39631E-page 129 PIC18F2420/2520/4420/4520 12.3.3 TIMER1 OSCILLATOR LAYOUT CONSIDERATIONS The Timer1 oscillator circuit draws very little power during operation. Due to the low-power nature of the oscillator, it may also be sensitive to rapidly changing signals in close proximity. The oscillator circuit, shown in Figure 12-3, should be located as close as possible to the microcontroller. There should be no circuits passing within the oscillator circuit boundaries other than VSS or VDD. If a high-speed circuit must be located near the oscillator (such as the CCP1 pin in Output Compare or PWM mode, or the primary oscillator using the OSC2 pin), a grounded guard ring around the oscillator circuit, as shown in Figure 12-4, may be helpful when used on a single-sided PCB or in addition to a ground plane. FIGURE 12-4: OSCILLATOR CIRCUIT WITH GROUNDED GUARD RING 12.5 If either of the CCP modules is configured to use Timer1 and generate a Special Event Trigger in Compare mode (CCP1M<3:0> or CCP2M<3:0> = 1011), this signal will reset Timer1. The trigger from CCP2 will also start an A/D conversion if the A/D module is enabled (see Section 15.3.4 "Special Event Trigger" for more information). The module must be configured as either a timer or a synchronous counter to take advantage of this feature. When used this way, the CCPRxH:CCPRxL register pair effectively becomes a Period register for Timer1. If Timer1 is running in Asynchronous Counter mode, this Reset operation may not work. In the event that a write to Timer1 coincides with a Special Event Trigger, the write operation will take precedence. Note: VDD VSS OSC1 OSC2 RC0 RC1 RC2 Note: Not drawn to scale. 12.4 Timer1 Interrupt The TMR1 register pair (TMR1H:TMR1L) increments from 0000h to FFFFh and rolls over to 0000h. The Timer1 interrupt, if enabled, is generated on overflow, which is latched in interrupt flag bit, TMR1IF (PIR1<0>). This interrupt can be enabled or disabled by setting or clearing the Timer1 Interrupt Enable bit, TMR1IE (PIE1<0>). Resetting Timer1 Using the CCP Special Event Trigger 12.6 The Special Event Triggers from the CCP2 module will not set the TMR1IF interrupt flag bit (PIR1<0>). Using Timer1 as a Real-Time Clock Adding an external LP oscillator to Timer1 (such as the one described in Section 12.3 "Timer1 Oscillator") gives users the option to include RTC functionality to their applications. This is accomplished with an inexpensive watch crystal to provide an accurate time base and several lines of application code to calculate the time. When operating in Sleep mode and using a battery or supercapacitor as a power source, it can completely eliminate the need for a separate RTC device and battery backup. The application code routine, RTCisr, shown in Example 12-1, demonstrates a simple method to increment a counter at one-second intervals using an Interrupt Service Routine. Incrementing the TMR1 register pair to overflow triggers the interrupt and calls the routine, which increments the seconds counter by one; additional counters for minutes and hours are incremented as the previous counter overflow. Since the register pair is 16 bits wide, counting up to overflow the register directly from a 32.768 kHz clock would take 2 seconds. To force the overflow at the required one-second intervals, it is necessary to preload it. The simplest method is to set the MSb of TMR1H with a BSF instruction. Note that the TMR1L register is never preloaded or altered; doing so may introduce cumulative error over many cycles. For this method to be accurate, Timer1 must operate in Asynchronous mode and the Timer1 overflow interrupt must be enabled (PIE1<0> = 1), as shown in the routine, RTCinit. The Timer1 oscillator must also be enabled and running at all times. DS39631E-page 130 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 12.7 Considerations in Asynchronous Counter Mode Following a Timer1 interrupt and an update to the TMR1 registers, the Timer1 module uses a falling edge on its clock source to trigger the next register update on the rising edge. If the update is completed after the clock input has fallen, the next rising edge will not be counted. If the application can reliably update TMR1 before the timer input goes low, no additional action is needed. Otherwise, an adjusted update can be performed following a later Timer1 increment. This can be done by EXAMPLE 12-1: monitoring TMR1L within the interrupt routine until it increments, and then updating the TMR1H:TMR1L register pair while the clock is low, or one-half of the period of the clock source. Assuming that Timer1 is being used as a Real-Time Clock, the clock source is a 32.768 kHz crystal oscillator; in this case, one half period of the clock is 15.25 s. The Real-Time Clock application code in Example 12-1 shows a typical ISR for Timer1, as well as the optional code required if the update cannot be done reliably within the required interval. IMPLEMENTING A REAL-TIME CLOCK USING A TIMER1 INTERRUPT SERVICE RTCinit MOVLW MOVWF CLRF MOVLW MOVWF CLRF CLRF MOVLW MOVWF BSF RETURN 80h TMR1H TMR1L b'00001111' T1CON secs mins .12 hours PIE1, TMR1IE RTCisr BTFSC BRA BTFSS BRA TMR1L,0 $-2 TMR1L,0 $-2 BSF BCF INCF MOVLW CPFSGT RETURN CLRF INCF MOVLW CPFSGT RETURN CLRF INCF MOVLW CPFSGT RETURN CLRF RETURN TMR1H, 7 PIR1, TMR1IF secs, F .59 secs secs mins, F .59 mins mins hours, F .23 hours hours (c) 2008 Microchip Technology Inc. ; Preload TMR1 register pair ; for 1 second overflow ; Configure for external clock, ; Asynchronous operation, external oscillator ; Initialize timekeeping registers ; ; Enable Timer1 interrupt ; ; ; ; ; ; ; Start ISR here Insert the next 4 lines of code when TMR1 can not be reliably updated before clock pulse goes low wait for TMR1L<0> to become clear (may already be clear) wait for TMR1L<0> to become set TMR1 has just incremented ; ; ; ; ; If TMR1 update can be completed before clock pulse goes low Preload for 1 sec overflow Clear interrupt flag Increment seconds 60 seconds elapsed? ; ; ; ; No, done Clear seconds Increment minutes 60 minutes elapsed? ; ; ; ; No, done clear minutes Increment hours 24 hours elapsed? ; No, done ; Reset hours ; Done DS39631E-page 131 PIC18F2420/2520/4420/4520 TABLE 12-2: Name REGISTERS ASSOCIATED WITH TIMER1 AS A TIMER/COUNTER Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 (1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 (1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 IPR1 PSPIE PSPIP TMR1L Timer1 Register Low Byte 50 TMR1H Timer1 Register High Byte 50 T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50 Legend: Shaded cells are not used by the Timer1 module. Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear. DS39631E-page 132 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 13.0 TIMER2 MODULE 13.1 The Timer2 module timer incorporates the following features: * 8-Bit Timer and Period registers (TMR2 and PR2, respectively) * Readable and writable (both registers) * Software programmable prescaler (1:1, 1:4 and 1:16) * Software programmable postscaler (1:1 through 1:16) * Interrupt on TMR2 to PR2 match * Optional use as the shift clock for the MSSP module The module is controlled through the T2CON register (Register 13-1), which enables or disables the timer and configures the prescaler and postscaler. Timer2 can be shut off by clearing control bit, TMR2ON (T2CON<2>), to minimize power consumption. A simplified block diagram of the module is shown in Figure 13-1. Timer2 Operation In normal operation, TMR2 is incremented from 00h on each clock (FOSC/4). A 4-bit counter/prescaler on the clock input gives direct input, divide-by-4 and divide-by16 prescale options; these are selected by the prescaler control bits, T2CKPS<1:0> (T2CON<1:0>). The value of TMR2 is compared to that of the Period register, PR2, on each clock cycle. When the two values match, the comparator generates a match signal as the timer output. This signal also resets the value of TMR2 to 00h on the next cycle and drives the output counter/postscaler (see Section 13.2 "Timer2 Interrupt"). The TMR2 and PR2 registers are both directly readable and writable. The TMR2 register is cleared on any device Reset, while the PR2 register initializes at FFh. Both the prescaler and postscaler counters are cleared on the following events: * a write to the TMR2 register * a write to the T2CON register * any device Reset (Power-on Reset, MCLR Reset, Watchdog Timer Reset or Brown-out Reset) TMR2 is not cleared when T2CON is written. REGISTER 13-1: T2CON: TIMER2 CONTROL REGISTER U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 -- T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 bit 7 bit 0 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 bit 7 Unimplemented: Read as `0' bit 6-3 T2OUTPS<3:0>: Timer2 Output Postscale Select bits 0000 = 1:1 Postscale 0001 = 1:2 Postscale * * * 1111 = 1:16 Postscale bit 2 TMR2ON: Timer2 On bit 1 = Timer2 is on 0 = Timer2 is off bit 1-0 T2CKPS<1:0>: Timer2 Clock Prescale Select bits 00 = Prescaler is 1 01 = Prescaler is 4 1x = Prescaler is 16 (c) 2008 Microchip Technology Inc. x = Bit is unknown DS39631E-page 133 PIC18F2420/2520/4420/4520 13.2 Timer2 Interrupt 13.3 Timer2 also can generate an optional device interrupt. The Timer2 output signal (TMR2 to PR2 match) provides the input for the 4-bit output counter/postscaler. This counter generates the TMR2 match interrupt flag which is latched in TMR2IF (PIR1<1>). The interrupt is enabled by setting the TMR2 Match Interrupt Enable bit, TMR2IE (PIE1<1>). Timer2 Output The unscaled output of TMR2 is available primarily to the CCP modules, where it is used as a time base for operations in PWM mode. Timer2 can optionally be used as the shift clock source for the MSSP module operating in SPI mode. Additional information is provided in Section 17.0 "Master Synchronous Serial Port (MSSP) Module". A range of 16 postscale options (from 1:1 through 1:16 inclusive) can be selected with the postscaler control bits, T2OUTPS<3:0> (T2CON<6:3>). FIGURE 13-1: TIMER2 BLOCK DIAGRAM 4 T2OUTPS<3:0> 1:1 to 1:16 Postscaler Set TMR2IF 2 T2CKPS<1:0> TMR2/PR2 Match Reset 1:1, 1:4, 1:16 Prescaler FOSC/4 TMR2 TMR2 Output (to PWM or MSSP) Comparator 8 PR2 8 8 Internal Data Bus TABLE 13-1: Name REGISTERS ASSOCIATED WITH TIMER2 AS A TIMER/COUNTER Bit 7 Bit 6 INTCON GIE/GIEH PEIE/GIEL Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 TMR2 T2CON PR2 Timer2 Register -- T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON 50 T2CKPS1 T2CKPS0 Timer2 Period Register 50 50 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Timer2 module. Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear. DS39631E-page 134 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 14.0 TIMER3 MODULE The Timer3 module timer/counter incorporates these features: * Software selectable operation as a 16-bit timer or counter * Readable and writable 8-bit registers (TMR3H and TMR3L) * Selectable clock source (internal or external) with device clock or Timer1 oscillator internal options * Interrupt-on-overflow * Module Reset on CCP Special Event Trigger REGISTER 14-1: A simplified block diagram of the Timer3 module is shown in Figure 14-1. A block diagram of the module's operation in Read/Write mode is shown in Figure 14-2. The Timer3 module is controlled through the T3CON register (Register 14-1). It also selects the clock source options for the CCP modules (see Section 15.1.1 "CCP Modules and Timer Resources" for more information). T3CON: TIMER3 CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 RD16 T3CCP2 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 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 RD16: 16-Bit Read/Write Mode Enable bit 1 = Enables register read/write of Timer3 in one 16-bit operation 0 = Enables register read/write of Timer3 in two 8-bit operations bit 6,3 T3CCP<2:1>: Timer3 and Timer1 to CCPx Enable bits 1x = Timer3 is the capture/compare clock source for the CCP modules 01 = Timer3 is the capture/compare clock source for CCP2; Timer1 is the capture/compare clock source for CCP1 00 = Timer1 is the capture/compare clock source for the CCP modules bit 5-4 T3CKPS<1:0>: Timer3 Input Clock Prescale Select bits 11 = 1:8 Prescale value 10 = 1:4 Prescale value 01 = 1:2 Prescale value 00 = 1:1 Prescale value bit 2 T3SYNC: Timer3 External Clock Input Synchronization Control bit (Not usable if the device clock comes from Timer1/Timer3.) When TMR3CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input When TMR3CS = 0: This bit is ignored. Timer3 uses the internal clock when TMR3CS = 0. bit 1 TMR3CS: Timer3 Clock Source Select bit 1 = External clock input from Timer1 oscillator or T13CKI (on the rising edge after the first falling edge) 0 = Internal clock (FOSC/4) bit 0 TMR3ON: Timer3 On bit 1 = Enables Timer3 0 = Stops Timer3 (c) 2008 Microchip Technology Inc. DS39631E-page 135 PIC18F2420/2520/4420/4520 14.1 The operating mode is determined by the clock select bit, TMR3CS (T3CON<1>). When TMR3CS is cleared (= 0), Timer3 increments on every internal instruction cycle (FOSC/4). When the bit is set, Timer3 increments on every rising edge of the Timer1 external clock input or the Timer1 oscillator, if enabled. Timer3 Operation Timer3 can operate in one of three modes: * Timer * Synchronous Counter * Asynchronous Counter FIGURE 14-1: As with Timer1, the RC1/T1OSI and RC0/T1OSO/ T13CKI pins become inputs when the Timer1 oscillator is enabled. This means the values of TRISC<1:0> are ignored and the pins are read as `0'. TIMER3 BLOCK DIAGRAM Timer1 Oscillator Timer1 Clock Input 1 T1OSO/T13CKI 1 FOSC/4 Internal Clock T1OSI Synchronize Prescaler 1, 2, 4, 8 Detect 0 0 2 T1OSCEN (1) Sleep Input TMR3CS Timer3 On/Off T3CKPS<1:0> T3SYNC TMR3ON CCP1/CCP2 Special Event Trigger CCP1/CCP2 Select from T3CON<6,3> Clear TMR3 Set TMR3IF on Overflow TMR3 High Byte TMR3L Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain. FIGURE 14-2: TIMER3 BLOCK DIAGRAM (16-BIT READ/WRITE MODE) Timer1 Clock Input Timer1 Oscillator 1 T13CKI/T1OSO 1 FOSC/4 Internal Clock T1OSI Synchronize Prescaler 1, 2, 4, 8 Detect 0 0 2 T1OSCEN(1) T3CKPS<1:0> T3SYNC TMR3ON Sleep Input TMR3CS CCP1/CCP2 Special Event Trigger CCP1/CCP2 Select from T3CON<6,3> Clear TMR3 Timer3 On/Off Set TMR3IF on Overflow TMR3 High Byte TMR3L 8 Read TMR1L Write TMR1L 8 8 TMR3H 8 8 Internal Data Bus Note 1: When enable bit, T1OSCEN, is cleared, the inverter and feedback resistor are turned off to eliminate power drain. DS39631E-page 136 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 14.2 Timer3 16-Bit Read/Write Mode 14.4 Timer3 Interrupt Timer3 can be configured for 16-bit reads and writes (see Figure 14-2). When the RD16 control bit (T3CON<7>) is set, the address for TMR3H is mapped to a buffer register for the high byte of Timer3. A read from TMR3L will load the contents of the high byte of Timer3 into the Timer3 High Byte Buffer register. This provides the user with the ability to accurately read all 16 bits of Timer1 without having to determine whether a read of the high byte, followed by a read of the low byte, has become invalid due to a rollover between reads. The TMR3 register pair (TMR3H:TMR3L) increments from 0000h to FFFFh and overflows to 0000h. The Timer3 interrupt, if enabled, is generated on overflow and is latched in interrupt flag bit, TMR3IF (PIR2<1>). This interrupt can be enabled or disabled by setting or clearing the Timer3 Interrupt Enable bit, TMR3IE (PIE2<1>). A write to the high byte of Timer3 must also take place through the TMR3H Buffer register. The Timer3 high byte is updated with the contents of TMR3H when a write occurs to TMR3L. This allows a user to write all 16 bits to both the high and low bytes of Timer3 at once. If either of the CCP modules is configured to use Timer3 and to generate a Special Event Trigger in Compare mode (CCP1M<3:0> or CCP2M<3:0> = 1011), this signal will reset Timer3. It will also start an A/D conversion if the A/D module is enabled (see Section 15.3.4 "Special Event Trigger" for more information). The high byte of Timer3 is not directly readable or writable in this mode. All reads and writes must take place through the Timer3 High Byte Buffer register. Writes to TMR3H do not clear the Timer3 prescaler. The prescaler is only cleared on writes to TMR3L. 14.3 Using the Timer1 Oscillator as the Timer3 Clock Source The Timer1 internal oscillator may be used as the clock source for Timer3. The Timer1 oscillator is enabled by setting the T1OSCEN (T1CON<3>) bit. To use it as the Timer3 clock source, the TMR3CS bit must also be set. As previously noted, this also configures Timer3 to increment on every rising edge of the oscillator source. 14.5 Resetting Timer3 Using the CCP Special Event Trigger The module must be configured as either a timer or synchronous counter to take advantage of this feature. When used this way, the CCPRxH:CCPRxL register pair effectively becomes a Period register for Timer3. If Timer3 is running in Asynchronous Counter mode, the Reset operation may not work. In the event that a write to Timer3 coincides with a Special Event Trigger from a CCP module, the write will take precedence. Note: The Special Event Triggers from the CCP2 module will not set the TMR3IF interrupt flag bit (PIR1<0>). The Timer1 oscillator is described in Section 12.0 "Timer1 Module". TABLE 14-1: Name INTCON REGISTERS ASSOCIATED WITH TIMER3 AS A TIMER/COUNTER Bit 7 Bit 6 GIE/GIEH PEIE/GIEL Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 TMR3L Timer3 Register Low Byte 51 TMR3H Timer3 Register High Byte 51 T1CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 50 T3CON RD16 T3CCP2 T3CKPS1 T3CKPS0 TMR3CS TMR3ON 51 T3CCP1 T3SYNC Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Timer3 module. (c) 2008 Microchip Technology Inc. DS39631E-page 137 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 138 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 15.0 CAPTURE/COMPARE/PWM (CCP) MODULES PIC18F2420/2520/4420/4520 devices all have two CCP (Capture/Compare/PWM) modules. Each module contains a 16-bit register which can operate as a 16-bit Capture register, a 16-bit Compare register or a PWM Master/Slave Duty Cycle register. In 28-pin devices, the two standard CCP modules (CCP1 and CCP2) operate as described in this chapter. In 40/ 44-pin devices, CCP1 is implemented as an Enhanced CCP module with standard Capture and Compare modes and Enhanced PWM modes. The ECCP implementation is discussed in Section 16.0 "Enhanced Capture/Compare/PWM (ECCP) Module". REGISTER 15-1: The capture and compare operations described in this chapter apply to all standard and Enhanced CCP modules. Note: Throughout this section and Section 16.0 "Enhanced Capture/Compare/PWM (ECCP) Module", references to the register and bit names for CCP modules are referred to generically by the use of `x' or `y' in place of the specific module number. Thus, "CCPxCON" might refer to the control register for CCP1, CCP2 or ECCP1. "CCPxCON" is used throughout these sections to refer to the module control register, regardless of whether the CCP module is a standard or enhanced implementation. CCPxCON: CCPx CONTROL REGISTER (28-PIN DEVICES) U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 -- -- DCxB1 DCxB0 CCPxM3 CCPxM2 CCPxM1 CCPxM0 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 DCxB<1:0>: PWM Duty Cycle bit 1 and bit 0 for CCPx Module Capture mode: Unused. Compare mode: Unused. PWM mode: These bits are the two LSbs (bit 1 and bit 0) of the 10-bit PWM duty cycle. The eight MSbs (DCxB<9:2>) of the duty cycle are found in CCPRxL. bit 3-0 CCPxM<3:0>: CCPx Module Mode Select bits 0000 = Capture/Compare/PWM disabled (resets CCPx module) 0001 = Reserved 0010 = Compare mode, toggle output on match (CCPxIF bit is set) 0011 = Reserved 0100 = Capture mode, every falling edge 0101 = Capture mode, every rising edge 0110 = Capture mode, every 4th rising edge 0111 = Capture mode, every 16th rising edge 1000 = Compare mode, initialize CCPx pin low; on compare match, force CCPx pin high (CCPxIF bit is set) 1001 = Compare mode, initialize CCPx pin high; on compare match, force CCPx pin low (CCPxIF bit is set) 1010 = Compare mode, generate software interrupt on compare match (CCPxIF bit is set, CCPx pin reflects I/O state) 1011 = Compare mode, trigger special event; reset timer; CCP2 match starts A/D conversion (CCPxIF bit is set) 11xx = PWM mode (c) 2008 Microchip Technology Inc. DS39631E-page 139 PIC18F2420/2520/4420/4520 15.1 CCP Module Configuration Each Capture/Compare/PWM module is associated with a control register (generically, CCPxCON) and a data register (CCPRx). The data register, in turn, is comprised of two 8-bit registers: CCPRxL (low byte) and CCPRxH (high byte). All registers are both readable and writable. 15.1.1 CCP MODULES AND TIMER RESOURCES The CCP modules utilize Timers 1, 2 or 3, depending on the mode selected. Timer1 and Timer3 are available to modules in Capture or Compare modes, while Timer2 is available for modules in PWM mode. TABLE 15-1: CCP MODE - TIMER RESOURCE CCP/ECCP Mode Timer Resource Capture Compare PWM Timer1 or Timer3 Timer1 or Timer3 Timer2 TABLE 15-2: The assignment of a particular timer to a module is determined by the Timer to CCP enable bits in the T3CON register (Register 14-1). Both modules may be active at any given time and may share the same timer resource if they are configured to operate in the same mode (Capture/Compare or PWM) at the same time. The interactions between the two modules are summarized in Figure 15-1 and Figure 15-2. In Timer1 in Asynchronous Counter mode, the capture operation will not work. 15.1.2 CCP2 PIN ASSIGNMENT The pin assignment for CCP2 (Capture input, Compare and PWM output) can change, based on device configuration. The CCP2MX Configuration bit determines which pin CCP2 is multiplexed to. By default, it is assigned to RC1 (CCP2MX = 1). If the Configuration bit is cleared, CCP2 is multiplexed with RB3. Changing the pin assignment of CCP2 does not automatically change any requirements for configuring the port pin. Users must always verify that the appropriate TRIS register is configured correctly for CCP2 operation, regardless of where it is located. INTERACTIONS BETWEEN CCP1 AND CCP2 FOR TIMER RESOURCES CCP1 Mode CCP2 Mode Interaction Capture Capture Each module can use TMR1 or TMR3 as the time base. The time base can be different for each CCP. Capture Compare CCP2 can be configured for the Special Event Trigger to reset TMR1 or TMR3 (depending upon which time base is used). Automatic A/D conversions on trigger event can also be done. Operation of CCP1 could be affected if it is using the same timer as a time base. Compare Capture CCP1 can be configured for the Special Event Trigger to reset TMR1 or TMR3 (depending upon which time base is used). Operation of CCP2 could be affected if it is using the same timer as a time base. Compare Compare Either module can be configured for the Special Event Trigger to reset the time base. Automatic A/D conversions on CCP2 trigger event can be done. Conflicts may occur if both modules are using the same time base. Capture PWM(1) None Compare PWM(1) None PWM(1) Capture None (1) PWM PWM(1) Note 1: Compare PWM(1) None Both PWMs will have the same frequency and update rate (TMR2 interrupt). Includes standard and Enhanced PWM operation. DS39631E-page 140 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 15.2 15.2.3 Capture Mode When the Capture mode is changed, a false capture interrupt may be generated. The user should keep the CCPxIE interrupt enable bit clear to avoid false interrupts. The interrupt flag bit, CCPxIF, should also be cleared following any such change in operating mode. In Capture mode, the CCPRxH:CCPRxL register pair captures the 16-bit value of the TMR1 or TMR3 register when an event occurs on the corresponding CCPx pin. An event is defined as one of the following: * * * * every falling edge every rising edge every 4th rising edge every 16th rising edge 15.2.4 Switching from one capture prescaler to another may generate an interrupt. Also, the prescaler counter will not be cleared; therefore, the first capture may be from a non-zero prescaler. Example 15-1 shows the recommended method for switching between capture prescalers. This example also clears the prescaler counter and will not generate the "false" interrupt. CCP PIN CONFIGURATION In Capture mode, the appropriate CCPx pin should be configured as an input by setting the corresponding TRIS direction bit. Note: 15.2.2 If RB3/CCP2 or RC1/CCP2 is configured as an output, a write to the port can cause a capture condition. EXAMPLE 15-1: TIMER1/TIMER3 MODE SELECTION The timers that are to be used with the capture feature (Timer1 and/or Timer3) must be running in Timer mode or Synchronized Counter mode. In Asynchronous Counter mode, the capture operation will not work. The timer to be used with each CCP module is selected in the T3CON register (see Section 15.1.1 "CCP Modules and Timer Resources"). FIGURE 15-1: CCP PRESCALER There are four prescaler settings in Capture mode; they are specified as part of the operating mode selected by the mode select bits (CCPxM<3:0>). Whenever the CCP module is turned off, or Capture mode is disabled, the prescaler counter is cleared. This means that any Reset will clear the prescaler counter. The event is selected by the mode select bits, CCPxM<3:0> (CCPxCON<3:0>). When a capture is made, the interrupt request flag bit, CCPxIF, is set; it must be cleared in software. If another capture occurs before the value in register CCPRx is read, the old captured value is overwritten by the new captured value. 15.2.1 SOFTWARE INTERRUPT CHANGING BETWEEN CAPTURE PRESCALERS (CCP2 SHOWN) CLRF MOVLW CCP2CON NEW_CAPT_PS MOVWF CCP2CON ; ; ; ; ; ; Turn CCP module off Load WREG with the new prescaler mode value and CCP ON Load CCP2CON with this value CAPTURE MODE OPERATION BLOCK DIAGRAM TMR3H Set CCP1IF T3CCP2 CCP1 pin Prescaler / 1, 4, 16 and Edge Detect CCP1CON<3:0> Q1:Q4 CCP2CON<3:0> 4 4 CCPR1L TMR1 Enable TMR1H TMR1L TMR3H TMR3L Set CCP2IF 4 T3CCP1 T3CCP2 CCP2 pin Prescaler / 1, 4, 16 TMR3 Enable CCPR1H T3CCP2 TMR3L and Edge Detect TMR3 Enable CCPR2H CCPR2L TMR1 Enable T3CCP2 T3CCP1 (c) 2008 Microchip Technology Inc. TMR1H TMR1L DS39631E-page 141 PIC18F2420/2520/4420/4520 15.3 15.3.2 Compare Mode TIMER1/TIMER3 MODE SELECTION In Compare mode, the 16-bit CCPRx register value is constantly compared against either the TMR1 or TMR3 register pair value. When a match occurs, the CCPx pin can be: Timer1 and/or Timer3 must be running in Timer mode or Synchronized Counter mode if the CCP module is using the compare feature. In Asynchronous Counter mode, the compare operation may not work. * * * * 15.3.3 driven high driven low toggled (high-to-low or low-to-high) remain unchanged (that is, reflects the state of the I/O latch) When the Generate Software Interrupt mode is chosen (CCPxM<3:0> = 1010), the corresponding CCPx pin is not affected. A CCP interrupt is generated when the CCPxIF interrupt flag is set while the CCPxIE bit is set. The action on the pin is based on the value of the mode select bits (CCPxM<3:0>). At the same time, the interrupt flag bit, CCPxIF, is set. 15.3.1 15.3.4 SPECIAL EVENT TRIGGER Both CCP modules are equipped with a Special Event Trigger. This is an internal hardware signal generated in Compare mode to trigger actions by other modules. The Special Event Trigger is enabled by selecting the Compare Special Event Trigger mode (CCPxM<3:0> = 1011). CCP PIN CONFIGURATION The user must configure the CCPx pin as an output by clearing the appropriate TRIS bit. Note: SOFTWARE INTERRUPT MODE Clearing the CCP2CON register will force the RB3 or RC1 compare output latch (depending on device configuration) to the default low level. This is not the PORTB or PORTC I/O data latch. For either CCP module, the Special Event Trigger resets the Timer register pair for whichever timer resource is currently assigned as the module's time base. This allows the CCPRx registers to serve as a programmable Period register for either timer. The Special Event Trigger for CCP2 can also start an A/D conversion. In order to do this, the A/D Converter must already be enabled. FIGURE 15-2: COMPARE MODE OPERATION BLOCK DIAGRAM CCPR1H Set CCP1IF CCPR1L Special Event Trigger (Timer1/Timer3 Reset) CCP1 pin Comparator Output Logic Compare Match S Q R TRIS Output Enable 4 CCP1CON<3:0> 0 TMR1H TMR1L 0 1 TMR3H TMR3L 1 T3CCP1 Special Event Trigger (Timer1/Timer3 Reset, A/D Trigger) T3CCP2 Set CCP2IF Comparator CCPR2H CCPR2L Compare Match CCP2 pin Output Logic 4 S Q R TRIS Output Enable CCP2CON<3:0> DS39631E-page 142 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 15-3: Name INTCON REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, TIMER1 AND TIMER3 Bit 7 Bit 6 Bit 5 GIE/GIEH PEIE/GIEL TMR0IE Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INT0IE RBIE TMR0IF INT0IF RBIF 49 IPEN SBOREN -- RI TO PD POR BOR 48 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 (1) PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 RCON PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 IPR2 TRISB PORTB Data Direction Register TRISC PORTC Data Direction Register 52 TMR1L Timer1 Register Low Byte 50 TMR1H Timer1 Register High Byte T1CON RD16 T1RUN Timer3 Register High Byte TMR3L Timer3 Register Low Byte RD16 T3CCP2 50 T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR3H T3CON 52 TMR1CS TMR1ON 50 51 51 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 51 CCPR1L Capture/Compare/PWM Register 1 Low Byte 51 CCPR1H Capture/Compare/PWM Register 1 High Byte 51 CCP1CON P1M1(1) P1M0(1) DC1B1 DC1B0 CCPR2L Capture/Compare/PWM Register 2 Low Byte CCPR2H Capture/Compare/PWM Register 2 High Byte CCP2CON -- -- DC2B1 DC2B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 51 51 51 CCP2M3 CCP2M2 CCP2M1 CCP2M0 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by Capture/Compare, Timer1 or Timer3. Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear. (c) 2008 Microchip Technology Inc. DS39631E-page 143 PIC18F2420/2520/4420/4520 15.4 15.4.1 PWM Mode In Pulse-Width Modulation (PWM) mode, the CCPx pin produces up to a 10-bit resolution PWM output. Since the CCP2 pin is multiplexed with a PORTB or PORTC data latch, the appropriate TRIS bit must be cleared to make the CCP2 pin an output. Clearing the CCP2CON register will force the RB3 or RC1 output latch (depending on device configuration) to the default low level. This is not the PORTB or PORTC I/O data latch. Note: Figure 15-3 shows a simplified block diagram of the CCP module in PWM mode. For a step-by-step procedure on how to set up the CCP module for PWM operation, see Section 15.4.4 "Setup for PWM Operation". FIGURE 15-3: SIMPLIFIED PWM BLOCK DIAGRAM The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the following formula: EQUATION 15-1: PWM Period = [(PR2) + 1] * 4 * TOSC * (TMR2 Prescale Value) PWM frequency is defined as 1/[PWM period]. When TMR2 is equal to PR2, the following three events occur on the next increment cycle: * TMR2 is cleared * The CCPx pin is set (exception: if PWM duty cycle = 0%, the CCPx pin will not be set) * The PWM duty cycle is latched from CCPRxL into CCPRxH Note: CCPxCON<5:4> Duty Cycle Registers CCPRxL 15.4.2 CCPRxH (Slave) CCPx Output R Comparator TMR2 (Note 1) Comparator S Clear Timer, CCPx pin and latch D.C. PR2 Q Corresponding TRIS bit Note 1: The 8-bit TMR2 value is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base. A PWM output (Figure 15-4) has a time base (period) and a time that the output stays high (duty cycle). The frequency of the PWM is the inverse of the period (1/period). FIGURE 15-4: PWM PERIOD The Timer2 postscalers (see Section 13.0 "Timer2 Module") are not used in the determination of the PWM frequency. The postscaler could be used to have a servo update rate at a different frequency than the PWM output. PWM DUTY CYCLE The PWM duty cycle is specified by writing to the CCPRxL register and to the CCPxCON<5:4> bits. Up to 10-bit resolution is available. The CCPRxL contains the eight MSbs and the CCPxCON<5:4> bits contain the two LSbs. This 10-bit value is represented by CCPRxL:CCPxCON<5:4>. The following equation is used to calculate the PWM duty cycle in time: EQUATION 15-2: PWM Duty Cycle = (CCPRXL:CCPXCON<5:4>) * TOSC * (TMR2 Prescale Value) CCPRxL and CCPxCON<5:4> can be written to at any time, but the duty cycle value is not latched into CCPRxH until after a match between PR2 and TMR2 occurs (i.e., the period is complete). In PWM mode, CCPRxH is a read-only register. PWM OUTPUT Period Duty Cycle TMR2 = PR2 TMR2 = Duty Cycle TMR2 = PR2 DS39631E-page 144 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 The CCPRxH register and a 2-bit internal latch are used to double-buffer the PWM duty cycle. This double-buffering is essential for glitchless PWM operation. EQUATION 15-3: F OSC log --------------- F PWM PWM Resolution (max) = -----------------------------bits log ( 2 ) When the CCPRxH and 2-bit latch match TMR2, concatenated with an internal 2-bit Q clock or 2 bits of the TMR2 prescaler, the CCPx pin is cleared. Note: The maximum PWM resolution (bits) for a given PWM frequency is given by the equation: TABLE 15-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz PWM Frequency Timer Prescaler (1, 4, 16) PR2 Value Maximum Resolution (bits) 15.4.3 If the PWM duty cycle value is longer than the PWM period, the CCPx pin will not be cleared. 2.44 kHz 9.77 kHz 39.06 kHz 312.50 kHz 416.67 kHz 16 4 1 1 1 1 FFh FFh FFh 3Fh 1Fh 17h 10 10 10 8 7 6.58 PWM AUTO-SHUTDOWN (CCP1 ONLY) The PWM auto-shutdown features of the Enhanced CCP module are also available to CCP1 in 28-pin devices. The operation of this feature is discussed in detail in Section 16.4.7 "Enhanced PWM Auto-Shutdown". Auto-shutdown features are not available for CCP2. 15.4.4 SETUP FOR PWM OPERATION The following steps should be taken when configuring the CCP module for PWM operation: 1. 2. 3. 4. 5. (c) 2008 Microchip Technology Inc. 156.25 kHz Set the PWM period by writing to the PR2 register. Set the PWM duty cycle by writing to the CCPRxL register and CCPxCON<5:4> bits. Make the CCPx pin an output by clearing the appropriate TRIS bit. Set the TMR2 prescale value, then enable Timer2 by writing to T2CON. Configure the CCPx module for PWM operation. DS39631E-page 145 PIC18F2420/2520/4420/4520 TABLE 15-5: Name INTCON REGISTERS ASSOCIATED WITH PWM AND TIMER2 Bit 7 Bit 6 GIE/GIEH PEIE/GIEL Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 IPEN SBOREN -- RI TO PD POR BOR 48 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE (1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 RCON TRISB PORTB Data Direction Register 52 TRISC PORTC Data Direction Register 52 TMR2 Timer2 Register 50 PR2 Timer2 Period Register 50 T2CON -- T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 CCPR1L Capture/Compare/PWM Register 1 Low Byte CCPR1H Capture/Compare/PWM Register 1 High Byte CCP1CON P1M1(1) P1M0(1) DC1B1 DC1B0 50 51 51 CCP1M3 CCP1M2 CCP1M1 CCP1M0 51 CCPR2L Capture/Compare/PWM Register 2 Low Byte 51 CCPR2H Capture/Compare/PWM Register 2 High Byte 51 CCP2CON ECCP1AS PWM1CON -- -- ECCPASE ECCPAS2 PRSEN PDC6(1) DC2B1 DC2B0 CCP2M3 CCP2M2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1) CCP2M1 51 PDC5(1) PDC4(1) PDC3(1) PDC2(1) 51 PDC1(1) CCP2M0 PDC0(1) 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by PWM or Timer2. Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear. DS39631E-page 146 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 16.0 ENHANCED CAPTURE/ COMPARE/PWM (ECCP) MODULE Note: The ECCP module is implemented only in 40/44-pin devices. In PIC18F4420/4520 devices, CCP1 is implemented as a standard CCP module with Enhanced PWM capabilities. These include the provision for 2 or 4 output channels, user-selectable polarity, dead-band control REGISTER 16-1: and automatic shutdown and restart. The enhanced features are discussed in detail in Section 16.4 "Enhanced PWM Mode". Capture, Compare and single output PWM functions of the ECCP module are the same as described for the standard CCP module. The control register for the Enhanced CCP module is shown in Register 16-2. It differs from the CCPxCON registers in PIC18F2420/2520 devices in that the two Most Significant bits are implemented to control PWM functionality. CCP1CON: ECCP CONTROL REGISTER (40/44-PIN DEVICES) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 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>: Enhanced PWM Output Configuration bits If CCP1M3:CCP1M2 = 00, 01, 10: xx = P1A assigned as capture/compare input/output; P1B, P1C, P1D assigned as port pins If CCP1M3:CCP1M2 = 11: 00 = Single output, P1A modulated; P1B, P1C, P1D assigned as port pins 01 = Full-bridge output forward, P1D modulated; P1A active; P1B, P1C inactive 10 = Half-bridge output, P1A, P1B modulated with dead-band control; P1C, P1D assigned as port pins 11 = Full-bridge output reverse, P1B modulated; P1C active; P1A, P1D inactive bit 5-4 DC1B<1:0>: PWM Duty Cycle bit 1 and bit 0 Capture mode: Unused. Compare mode: Unused. PWM mode: These bits are the two LSbs of the 10-bit PWM duty cycle. The eight MSbs of the duty cycle are found in CCPR1L. bit 3-0 CCP1M<3:0>: Enhanced CCP Mode Select bits 0000 = Capture/Compare/PWM off (resets ECCP module) 0001 = Reserved 0010 = Compare mode, toggle output on match 0011 = Capture mode 0100 = Capture mode, every falling edge 0101 = Capture mode, every rising edge 0110 = Capture mode, every 4th rising edge 0111 = Capture mode, every 16th rising edge 1000 = Compare mode, initialize CCP1 pin low; set output on compare match (set CCP1IF) 1001 = Compare mode, initialize CCP1 pin high; clear output on compare match (set CCP1IF) 1010 = Compare mode, generate software interrupt only; CCP1 pin reverts to I/O state 1011 = Compare mode, trigger special event (ECCP resets TMR1 or TMR3, sets CCP1IF bit) 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 (c) 2008 Microchip Technology Inc. DS39631E-page 147 PIC18F2420/2520/4420/4520 In addition to the expanded range of modes available through the CCP1CON register and ECCP1AS register, the ECCP module has an additional register associated with Enhanced PWM operation and auto-shutdown features. It is: * PWM1CON (PWM Dead-Band Delay) 16.1 ECCP Outputs and Configuration The Enhanced CCP module may have up to four PWM outputs, depending on the selected operating mode. These outputs, designated P1A through P1D, are multiplexed with I/O pins on PORTC and PORTD. The outputs that are active depend on the CCP operating mode selected. The pin assignments are summarized in Table 16-1. To configure the I/O pins as PWM outputs, the proper PWM mode must be selected by setting the P1M<1:0> and CCP1M<3:0> bits. The appropriate TRISC and TRISD direction bits for the port pins must also be set as outputs. 16.1.1 ECCP MODULES AND TIMER RESOURCES Like the standard CCP modules, the ECCP module can utilize Timers 1, 2 or 3, depending on the mode selected. Timer1 and Timer3 are available for modules in Capture or Compare modes, while Timer2 is available for modules in PWM mode. Interactions between the standard and Enhanced CCP modules are identical to those described for standard CCP modules. Additional details on timer resources are provided in Section 15.1.1 "CCP Modules and Timer Resources". TABLE 16-1: 16.2 Capture and Compare Modes Except for the operation of the Special Event Trigger discussed below, the Capture and Compare modes of the ECCP module are identical in operation to that of CCP2. These are discussed in detail in Section 15.2 "Capture Mode" and Section 15.3 "Compare Mode". No changes are required when moving between 28-pin and 40/44-pin devices. 16.2.1 SPECIAL EVENT TRIGGER The Special Event Trigger output of ECCP resets the TMR1 or TMR3 register pair, depending on which timer resource is currently selected. This allows the CCPR1 register to effectively be a 16-Bit Programmable Period register for Timer1 or Timer3. 16.3 Standard PWM Mode When configured in Single Output mode, the ECCP module functions identically to the standard CCP module in PWM mode, as described in Section 15.4 "PWM Mode". This is also sometimes referred to as "Compatible CCP" mode, as in Table 16-1. Note: When setting up single output PWM operations, users are free to use either of the processes described in Section 15.4.4 "Setup for PWM Operation" or Section 16.4.9 "Setup for PWM Operation". The latter is more generic and will work for either single or multi-output PWM. PIN ASSIGNMENTS FOR VARIOUS ECCP MODES ECCP Mode CCP1CON Configuration RC2 RD5 RD6 RD7 All 40/44-Pin Devices: Compatible CCP 00xx 11xx CCP1 RD5/PSP5 RD6/PSP6 RD7/PSP7 Dual PWM 10xx 11xx P1A P1B RD6/PSP6 RD7/PSP7 Quad PWM x1xx 11xx P1A P1B P1C P1D Legend: x = Don't care. Shaded cells indicate pin assignments not used by ECCP in a given mode. DS39631E-page 148 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 16.4 16.4.1 Enhanced PWM Mode The Enhanced PWM mode provides additional PWM output options for a broader range of control applications. The module is a backward compatible version of the standard CCP module and offers up to four outputs, designated P1A through P1D. Users are also able to select the polarity of the signal (either active-high or active-low). The module's output mode and polarity are configured by setting the P1M<1:0> and CCP1M<3:0> bits of the CCP1CON register. Figure 16-1 shows a simplified block diagram of PWM operation. All control registers are double-buffered and are loaded at the beginning of a new PWM cycle (the period boundary when Timer2 resets) in order to prevent glitches on any of the outputs. The exception is the PWM Dead-Band Delay register, PWM1CON, which is loaded at either the duty cycle boundary or the period boundary (whichever comes first). Because of the buffering, the module waits until the assigned timer resets instead of starting immediately. This means that Enhanced PWM waveforms do not exactly match the standard PWM waveforms, but are instead offset by one full instruction cycle (4 TOSC). PWM PERIOD The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the following equation. EQUATION 16-1: PWM Period = PWM frequency is defined as 1/[PWM period]. When TMR2 is equal to PR2, the following three events occur on the next increment cycle: * TMR2 is cleared * The CCP1 pin is set (if PWM duty cycle = 0%, the CCP1 pin will not be set) * The PWM duty cycle is copied from CCPR1L into CCPR1H Note: As before, the user must manually configure the appropriate TRIS bits for output. FIGURE 16-1: [(PR2) + 1] * 4 * TOSC * (TMR2 Prescale Value) The Timer2 postscaler (see Section 13.0 "Timer2 Module") is not used in the determination of the PWM frequency. The postscaler could be used to have a servo update rate at a different frequency than the PWM output. SIMPLIFIED BLOCK DIAGRAM OF THE ENHANCED PWM MODULE CCP1CON<5:4> Duty Cycle Registers CCP1M<3:0> 4 P1M1<1:0> 2 CCPR1L CCP1/P1A CCP1/P1A TRISx<x> CCPR1H (Slave) P1B R Comparator Q Output Controller P1B TRISx<x> P1C TMR2 Comparator PR2 (Note 1) P1C TRISx<x> S P1D Clear Timer, set CCP1 pin and latch D.C. P1D TRISx<x> PWM1CON Note: The 8-bit TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base. (c) 2008 Microchip Technology Inc. DS39631E-page 149 PIC18F2420/2520/4420/4520 16.4.2 PWM DUTY CYCLE EQUATION 16-3: The PWM duty cycle is specified by writing to the CCPR1L register and to the CCP1CON<5:4> bits. Up to 10-bit resolution is available. The CCPR1L contains the eight MSbs and the CCP1CON<5:4> bits contain the two LSbs. This 10-bit value is represented by CCPR1L:CCP1CON<5:4>. The PWM duty cycle is calculated by the following equation. ( log FOSC FPWM PWM Resolution (max) = log(2) Note: EQUATION 16-2: PWM Duty Cycle = 16.4.3 (CCPR1L:CCP1CON<5:4>) * TOSC * (TMR2 Prescale Value) CCPR1L and CCP1CON<5:4> can be written to at any time, but the duty cycle value is not copied into CCPR1H until a match between PR2 and TMR2 occurs (i.e., the period is complete). In PWM mode, CCPR1H is a read-only register. The CCPR1H register and a 2-bit internal latch are used to double-buffer the PWM duty cycle. This double-buffering is essential for glitchless PWM operation. When the CCPR1H and 2-bit latch match TMR2, concatenated with an internal 2-bit Q clock or two bits of the TMR2 prescaler, the CCP1 pin is cleared. The maximum PWM resolution (bits) for a given PWM frequency is given by the following equation. TABLE 16-2: ) bits If the PWM duty cycle value is longer than the PWM period, the CCP1 pin will not be cleared. PWM OUTPUT CONFIGURATIONS The P1M<1:0> bits in the CCP1CON register allow one of four configurations: * * * * Single Output Half-Bridge Output Full-Bridge Output, Forward mode Full-Bridge Output, Reverse mode The Single Output mode is the standard PWM mode discussed in Section 16.4 "Enhanced PWM Mode". The Half-Bridge and Full-Bridge Output modes are covered in detail in the sections that follow. The general relationship of the outputs in all configurations is summarized in Figure 16-2 and Figure 16-3. EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz PWM Frequency Timer Prescaler (1, 4, 16) PR2 Value Maximum Resolution (bits) DS39631E-page 150 2.44 kHz 9.77 kHz 39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz 16 4 1 1 1 1 FFh FFh FFh 3Fh 1Fh 17h 10 10 10 8 7 6.58 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 16-2: PWM OUTPUT RELATIONSHIPS (ACTIVE-HIGH STATE) 0 CCP1CON<7:6> 00 (Single Output) Duty Cycle SIGNAL PR2 + 1 Period P1A Modulated Delay(1) Delay(1) P1A Modulated 10 (Half-Bridge) P1B Modulated P1A Active 01 (Full-Bridge, Forward) P1B Inactive P1C Inactive P1D Modulated P1A Inactive 11 (Full-Bridge, Reverse) P1B Modulated P1C Active P1D Inactive FIGURE 16-3: PWM OUTPUT RELATIONSHIPS (ACTIVE-LOW STATE) CCP1CON<7:6> 00 (Single Output) SIGNAL 0 Duty Cycle PR2 + 1 Period P1A Modulated P1A Modulated 10 (Half-Bridge) Delay(1) Delay(1) P1B Modulated P1A Active 01 (Full-Bridge, Forward) P1B Inactive P1C Inactive P1D Modulated P1A Inactive 11 (Full-Bridge, Reverse) P1B Modulated P1C Active P1D Inactive Relationships: * Period = 4 * TOSC * (PR2 + 1) * (TMR2 Prescale Value) * Duty Cycle = TOSC * (CCPR1L<7:0>:CCP1CON<5:4>) * (TMR2 Prescale Value) * Delay = 4 * TOSC * (PWM1CON<6:0>) Note 1: Dead-band delay is programmed using the PWM1CON register (see Section 16.4.6 "Programmable Dead-Band Delay"). (c) 2008 Microchip Technology Inc. DS39631E-page 151 PIC18F2420/2520/4420/4520 16.4.4 HALF-BRIDGE MODE FIGURE 16-4: In the Half-Bridge Output mode, two pins are used as outputs to drive push-pull loads. The PWM output signal is output on the P1A pin, while the complementary PWM output signal is output on the P1B pin (Figure 16-4). This mode can be used for half-bridge applications, as shown in Figure 16-5, or for full-bridge applications where four power switches are being modulated with two PWM signals. In Half-Bridge Output mode, the programmable deadband delay can be used to prevent shoot-through current in half-bridge power devices. The value of bits, PDC<6:0>, sets the number of instruction cycles before the output is driven active. If the value is greater than the duty cycle, the corresponding output remains inactive during the entire cycle. See Section 16.4.6 "Programmable Dead-Band Delay" for more details of the dead-band delay operations. HALF-BRIDGE PWM OUTPUT Period Period Duty Cycle P1A(2) td td P1B(2) (1) (1) (1) td = Dead-Band Delay Note 1: At this time, the TMR2 register is equal to the PR2 register. 2: Output signals are shown as active-high. Since the P1A and P1B outputs are multiplexed with the PORTC<2> and PORTD<5> data latches, the TRISC<2> and TRISD<5> bits must be cleared to configure P1A and P1B as outputs. FIGURE 16-5: EXAMPLES OF HALF-BRIDGE OUTPUT MODE APPLICATIONS V+ Standard Half-Bridge Circuit ("Push-Pull") PIC18F4X2X FET Driver + V - P1A Load FET Driver + V - P1B VHalf-Bridge Output Driving a Full-Bridge Circuit V+ PIC18F4X2X FET Driver FET Driver P1A FET Driver Load FET Driver P1B V- DS39631E-page 152 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 16.4.5 FULL-BRIDGE MODE In Full-Bridge Output mode, four pins are used as outputs; however, only two outputs are active at a time. In the Forward mode, pin P1A is continuously active and pin P1D is modulated. In the Reverse mode, pin P1C is continuously active and pin P1B is modulated. These are illustrated in Figure 16-6. FIGURE 16-6: P1A, P1B, P1C and P1D outputs are multiplexed with the PORTC<2> and PORTD<7:5> data latches. The TRISC<2> and TRISD<7:5> bits must be cleared to make the P1A, P1B, P1C and P1D pins outputs. FULL-BRIDGE PWM OUTPUT Forward Mode Period P1A (2) Duty Cycle P1B(2) P1C(2) P1D(2) (1) (1) Reverse Mode Period Duty Cycle P1A(2) P1B(2) P1C(2) P1D(2) (1) (1) Note 1: At this time, the TMR2 register is equal to the PR2 register. Note 2: Output signal is shown as active-high. (c) 2008 Microchip Technology Inc. DS39631E-page 153 PIC18F2420/2520/4420/4520 FIGURE 16-7: EXAMPLE OF FULL-BRIDGE OUTPUT MODE APPLICATION V+ PIC18F4X2X FET Driver QC QA FET Driver P1A Load P1B FET Driver P1C FET Driver QD QB VP1D 16.4.5.1 Direction Change in Full-Bridge Mode In the Full-Bridge Output mode, the P1M1 bit in the CCP1CON register allows user to control the forward/ reverse direction. When the application firmware changes this direction control bit, the module will assume the new direction on the next PWM cycle. Just before the end of the current PWM period, the modulated outputs (P1B and P1D) are placed in their inactive state, while the unmodulated outputs (P1A and P1C) are switched to drive in the opposite direction. This occurs in a time interval of 4 TOSC * (Timer2 Prescale Value) before the next PWM period begins. The Timer2 prescaler will be either 1, 4 or 16, depending on the value of the T2CKPS<1:0> bits (T2CON<1:0>). During the interval from the switch of the unmodulated outputs to the beginning of the next period, the modulated outputs (P1B and P1D) remain inactive. This relationship is shown in Figure 16-8. Note that in the Full-Bridge Output mode, the CCP1 module does not provide any dead-band delay. In general, since only one output is modulated at all times, dead-band delay is not required. However, there is a situation where a dead-band delay might be required. This situation occurs when both of the following conditions are true: 1. 2. Figure 16-9 shows an example where the PWM direction changes from forward to reverse at a near 100% duty cycle. At time t1, the outputs P1A and P1D become inactive, while output P1C becomes active. In this example, since the turn-off time of the power devices is longer than the turn-on time, a shoot-through current may flow through power devices, QC and QD (see Figure 16-7), for the duration of `t'. The same phenomenon will occur to power devices, QA and QB, for PWM direction change from reverse to forward. If changing PWM direction at high duty cycle is required for an application, one of the following requirements must be met: 1. 2. Reduce PWM for a PWM period before changing directions. 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. The direction of the PWM output changes when the duty cycle of the output is at or near 100%. The turn-off time of the power switch, including the power device and driver circuit, is greater than the turn-on time. DS39631E-page 154 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 16-8: PWM DIRECTION CHANGE Period(1) SIGNAL Period P1A (Active-High) P1B (Active-High) DC P1C (Active-High) (Note 2) P1D (Active-High) DC Note 1: The direction bit in the CCP1 Control register (CCP1CON<7>) is written any time during the PWM cycle. 2: When changing directions, the P1A and P1C signals switch before the end of the current PWM cycle at intervals of 4 TOSC, 16 TOSC or 64 TOSC, depending on the Timer2 prescaler value. The modulated P1B and P1D signals are inactive at this time. FIGURE 16-9: PWM DIRECTION CHANGE AT NEAR 100% DUTY CYCLE Forward Period t1 Reverse Period P1A(1) P1B(1) DC P1C(1) P1D(1) DC tON(2) External Switch C(1) tOFF(3) External Switch D(1) Potential Shoot-Through Current(1) Note 1: 2: 3: t = tOFF - tON(2,3) All signals are shown as active-high. tON is the turn-on delay of power switch, QC, and its driver. tOFF is the turn-off delay of power switch, QD, and its driver. (c) 2008 Microchip Technology Inc. DS39631E-page 155 PIC18F2420/2520/4420/4520 16.4.6 Note: PROGRAMMABLE DEAD-BAND DELAY Programmable dead-band delay is not implemented in 28-pin devices with standard CCP modules. In half-bridge applications where all power switches are modulated at the PWM frequency at all times, the power switches normally require more time to turn off than to turn on. If both the upper and lower power switches are switched at the same time (one turned on and the other turned off), both switches may be on for a short period of time until one switch completely turns off. During this brief interval, a very high current (shootthrough current) may flow through both power switches, shorting the bridge supply. To avoid this potentially destructive shoot-through current from flowing during switching, turning on either of the power switches is normally delayed to allow the other switch to completely turn off. In the Half-Bridge Output mode, a digitally programmable dead-band delay is available to avoid shoot-through current from destroying the bridge power switches. The delay occurs at the signal transition from the nonactive state to the active state (see Figure 16-4 for illustration). Bits, PDC<6:0>, of the PWM1CON register (Register 16-2) set the delay period in terms of microcontroller instruction cycles (TCY or 4 TOSC). These bits are not available on 28-pin devices as the standard CCP module does not support half-bridge operation. 16.4.7 ENHANCED PWM AUTO-SHUTDOWN When the CCP1 is programmed for any of the Enhanced PWM modes, the active output pins may be configured for auto-shutdown. Auto-shutdown immediately places the Enhanced PWM output pins into a defined shutdown state when a shutdown event occurs. REGISTER 16-2: A shutdown event can be caused by either of the comparator modules, a low level on the Fault input pin (FLT0) or any combination of these three sources. The comparators may be used to monitor a voltage input proportional to a current being monitored in the bridge circuit. If the voltage exceeds a threshold, the comparator switches state and triggers a shutdown. Alternatively, a low digital signal on FLT0 can also trigger a shutdown. The auto-shutdown feature can be disabled by not selecting any auto-shutdown sources. The autoshutdown sources to be used are selected using the ECCPAS<2:0> bits (ECCP1AS<6:4>). When a shutdown occurs, the output pins are asynchronously placed in their shutdown states, specified by the PSSAC<1:0> and PSSBD<1:0> bits (ECCPAS<2:0>). Each pin pair (P1A/P1C and P1B/ P1D) may be set to drive high, drive low or be tri-stated (not driving). The ECCPASE bit (ECCP1AS<7>) is also set to hold the Enhanced PWM outputs in their shutdown states. The ECCPASE bit is set by hardware when a shutdown event occurs. If automatic restarts are not enabled, the ECCPASE bit is cleared by firmware when the cause of the shutdown clears. If automatic restarts are enabled, the ECCPASE bit is automatically cleared when the cause of the auto-shutdown has cleared. If the ECCPASE bit is set when a PWM period begins, the PWM outputs remain in their shutdown state for that entire PWM period. When the ECCPASE bit is cleared, the PWM outputs will return to normal operation at the beginning of the next PWM period. Note: Writing to the ECCPASE bit is disabled while a shutdown condition is active. PWM1CON: PWM DEAD-BAND DELAY REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 PRSEN PDC6(1) PDC5(1) PDC4(1) PDC3(1) PDC2(1) PDC1(1) PDC0(1) 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 PDC6:PDC0: PWM Delay Count bits(1) Delay time, in number of FOSC/4 (4 * TOSC) cycles, between the scheduled and actual time for a PWM signal to transition to active. Note 1: Reserved on 28-pin devices; maintain these bits clear. DS39631E-page 156 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 16-3: ECCP1AS: ECCP AUTO-SHUTDOWN CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 ECCPASE ECCPAS2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PSSBD1(1) PSSBD0(1) bit 7 bit 0 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 111 = FLT0 or Comparator 1 or Comparator 2 110 = FLT0 or Comparator 2 101 = FLT0 or Comparator 1 100 = FLT0 011 = Either Comparator 1 or 2 010 = Comparator 2 output 001 = Comparator 1 output 000 = Auto-shutdown is disabled bit 3-2 PSSAC<1:0>: Pins A and C Shutdown State Control bits 1x = Pins A and C are tri-state (40/44-pin devices); PWM output is tri-state (28-pin devices) 01 = Drive Pins A and C to `1' 00 = Drive Pins A and C to `0' bit 1-0 PSSBD<1:0>: Pins B and D Shutdown State Control bits(1) 1x = Pins B and D tri-state 01 = Drive Pins B and D to `1' 00 = Drive Pins B and D to `0' Note 1: Reserved on 28-pin devices; maintain these bits clear. (c) 2008 Microchip Technology Inc. DS39631E-page 157 PIC18F2420/2520/4420/4520 16.4.7.1 Auto-Shutdown and Automatic Restart The auto-shutdown feature can be configured to allow automatic restarts of the module following a shutdown event. This is enabled by setting the PRSEN bit of the PWM1CON register (PWM1CON<7>). In Shutdown mode with PRSEN = 1 (Figure 16-10), the ECCPASE bit will remain set for as long as the cause of the shutdown continues. When the shutdown condition clears, the ECCPASE bit is cleared. If PRSEN = 0 (Figure 16-11), once a shutdown condition occurs, the ECCPASE bit will remain set until it is cleared by firmware. Once ECCPASE is cleared, the Enhanced PWM will resume at the beginning of the next PWM period. Note: Writing to the ECCPASE bit is disabled while a shutdown condition is active. Independent of the PRSEN bit setting, if the autoshutdown source is one of the comparators, the shutdown condition is a level. The ECCPASE bit cannot be cleared as long as the cause of the shutdown persists. The Auto-Shutdown mode can be forced by writing a `1' to the ECCPASE bit. FIGURE 16-10: 16.4.8 START-UP CONSIDERATIONS When the ECCP module is used in the PWM mode, the application hardware must use the proper external pullup and/or pull-down resistors on the PWM output pins. When the microcontroller is released from Reset, all of the I/O pins are in the high-impedance state. The external circuits must keep the power switch devices in the OFF state until the microcontroller drives the I/O pins with the proper signal levels or activates the PWM output(s). The CCP1M<1:0> bits (CCP1CON<1:0>) allow the user to choose whether the PWM output signals are active-high or active-low for each pair of PWM output pins (P1A/P1C and P1B/P1D). The PWM output polarities must be selected before the PWM pins are configured as outputs. Changing the polarity configuration while the PWM pins are configured as outputs is not recommended, since it may result in damage to the application circuits. The P1A, P1B, P1C and P1D output latches may not be in the proper states when the PWM module is initialized. Enabling the PWM pins for output at the same time as the ECCP module may cause damage to the application circuit. The ECCP module must be enabled in the proper output mode and complete a full PWM cycle before configuring the PWM pins as outputs. The completion of a full PWM cycle is indicated by the TMR2IF bit being set as the second PWM period begins. PWM AUTO-SHUTDOWN (PRSEN = 1, AUTO-RESTART ENABLED) PWM Period Shutdown Event ECCPASE bit PWM Activity Normal PWM Start of PWM Period FIGURE 16-11: Shutdown Shutdown Event Occurs Event Clears PWM Resumes PWM AUTO-SHUTDOWN (PRSEN = 0, AUTO-RESTART DISABLED) PWM Period Shutdown Event ECCPASE bit PWM Activity Normal PWM Start of PWM Period DS39631E-page 158 ECCPASE Cleared by Shutdown Shutdown Firmware PWM Event Occurs Event Clears Resumes (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 16.4.9 SETUP FOR PWM OPERATION The following steps should be taken when configuring the ECCP module for PWM operation: 1. Configure the PWM pins, P1A and P1B (and P1C and P1D, if used), as inputs by setting the corresponding TRIS bits. 2. Set the PWM period by loading the PR2 register. 3. If auto-shutdown is required: * Disable auto-shutdown (ECCPASE = 0) * Configure source (FLT0, Comparator 1 or Comparator 2) * Wait for non-shutdown condition 4. Configure the ECCP module for the desired PWM mode and configuration by loading the CCP1CON register with the appropriate values: * Select one of the available output configurations and direction with the P1M<1:0> bits. * Select the polarities of the PWM output signals with the CCP1M<3:0> bits. 5. Set the PWM duty cycle by loading the CCPR1L register and CCP1CON<5:4> bits. 6. For Half-Bridge Output mode, set the deadband delay by loading PWM1CON<6:0> with the appropriate value. 7. If auto-shutdown operation is required, load the ECCP1AS register: * Select the auto-shutdown sources using the ECCPAS<2:0> bits. * Select the shutdown states of the PWM output pins using the PSSAC<1:0> and PSSBD<1:0> bits. * Set the ECCPASE bit (ECCP1AS<7>). * Configure the comparators using the CMCON register. * Configure the comparator inputs as analog inputs. 8. If auto-restart operation is required, set the PRSEN bit (PWM1CON<7>). 9. Configure and start TMR2: * Clear the TMR2 interrupt flag bit by clearing the TMR2IF bit (PIR1<1>). * Set the TMR2 prescale value by loading the T2CKPS bits (T2CON<1:0>). * Enable Timer2 by setting the TMR2ON bit (T2CON<2>). 10. Enable PWM outputs after a new PWM cycle has started: * Wait until TMRx overflows (TMRxIF bit is set). * Enable the CCP1/P1A, P1B, P1C and/or P1D pin outputs by clearing the respective TRIS bits. * Clear the ECCPASE bit (ECCP1AS<7>). (c) 2008 Microchip Technology Inc. 16.4.10 OPERATION IN POWER-MANAGED MODES In Sleep mode, all clock sources are disabled. Timer2 will not increment and the state of the module will not change. If the ECCP pin is driving a value, it will continue to drive that value. When the device wakes up, it will continue from this state. If Two-Speed Start-ups are enabled, the initial start-up frequency from INTOSC and the postscaler may not be stable immediately. In PRI_IDLE mode, the primary clock will continue to clock the ECCP module without change. In all other power-managed modes, the selected power-managed mode clock will clock Timer2. Other power-managed mode clocks will most likely be different than the primary clock frequency. 16.4.10.1 Operation with Fail-Safe Clock Monitor If the Fail-Safe Clock Monitor is enabled, a clock failure will force the device into the power-managed RC_RUN mode and the OSCFIF bit (PIR2<7>) will be set. The ECCP will then be clocked from the internal oscillator clock source, which may have a different clock frequency than the primary clock. See the previous section for additional details. 16.4.11 EFFECTS OF A RESET Both Power-on Reset and subsequent Resets will force all ports to Input mode and the CCP registers to their Reset states. This forces the Enhanced CCP module to reset to a state compatible with the standard CCP module. DS39631E-page 159 PIC18F2420/2520/4420/4520 TABLE 16-3: Name INTCON RCON REGISTERS ASSOCIATED WITH ECCP MODULE AND TIMER1 TO TIMER3 Bit 7 Bit 6 GIE/GIEH PEIE/GIEL IPEN SBOREN Reset Values on page Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 -- RI TO PD POR BOR 48 PIR1 PSPIF ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 TRISB PORTB Data Direction Register 52 TRISC PORTC Data Direction Register 52 TRISD PORTD Data Direction Register 52 TMR1L Timer1 Register Low Byte 50 TMR1H Timer1 Register High Byte 50 T1CON TMR2 T2CON RD16 T1RUN T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON Timer2 Register -- 50 50 T2OUTPS3 T2OUTPS2 T2OUTPS1 T2OUTPS0 TMR2ON T2CKPS1 T2CKPS0 50 PR2 Timer2 Period Register 50 TMR3L Timer3 Register Low Byte 51 TMR3H Timer3 Register High Byte T3CON RD16 T3CCP2 51 T3CKPS1 T3CKPS0 T3CCP1 T3SYNC TMR3CS TMR3ON 51 CCPR1L Capture/Compare/PWM Register 1 Low Byte 51 CCPR1H Capture/Compare/PWM Register 1 High Byte 51 CCP1CON ECCP1AS PWM1CON Legend: Note 1: P1M1 (1) P1M0(1) ECCPASE ECCPAS2 PRSEN PDC6(1) DC1B1 DC1B0 CCP1M3 CCP1M2 ECCPAS1 ECCPAS0 PSSAC1 PSSAC0 PDC5(1) PDC4(1) PDC3(1) PDC2(1) CCP1M1 CCP1M0 PSSBD1(1) PSSBD0(1) PDC1(1) PDC0(1) 51 51 51 -- = unimplemented, read as `0'. Shaded cells are not used during ECCP operation. These bits are unimplemented on 28-pin devices; always maintain these bits clear. DS39631E-page 160 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.0 17.1 MASTER SYNCHRONOUS SERIAL PORT (MSSP) MODULE Master SSP (MSSP) Module Overview The Master Synchronous Serial Port (MSSP) module is a serial interface, useful for communicating with other peripheral or microcontroller devices. These peripheral devices may be serial EEPROMs, shift registers, display drivers, A/D Converters, etc. The MSSP module can operate in one of two modes: * Serial Peripheral Interface (SPI) * Inter-Integrated Circuit (I2C) - Full Master mode - Slave mode (with general address call) 17.3 SPI Mode The SPI mode allows 8 bits of data to be synchronously transmitted and received simultaneously. All four modes of SPI are supported. To accomplish communication, typically three pins are used: * Serial Data Out (SDO) - RC5/SDO * Serial Data In (SDI) - RC4/SDI/SDA * Serial Clock (SCK) - RC3/SCK/SCL Additionally, a fourth pin may be used when in a Slave mode of operation: * Slave Select (SS) - RA5/SS Figure 17-1 shows the block diagram of the MSSP module when operating in SPI mode. FIGURE 17-1: MSSP BLOCK DIAGRAM (SPI MODE) The I2C interface supports the following modes in hardware: Internal Data Bus Read * Master mode * Multi-Master mode * Slave mode 17.2 Control Registers The MSSP module has three associated registers. These include a status register (SSPSTAT) and two control registers (SSPCON1 and SSPCON2). The use of these registers and their individual configuration bits differ significantly depending on whether the MSSP module is operated in SPI or I2C mode. Additional details are provided under the individual sections. Write SSPBUF reg RC4/SDI/SDA SSPSR reg RC5/SDO RA5/AN4/SS/ HLVDIN/C2OUT Shift Clock bit 0 SS Control Enable Edge Select 2 Clock Select RC3/SCK/ SCL SSPM<3:0> SMP:CKE 4 TMR2 Output 2 2 Edge Select Prescaler TOSC 4, 16, 64 ( ) Data to TX/RX in SSPSR TRIS bit (c) 2008 Microchip Technology Inc. DS39631E-page 161 PIC18F2420/2520/4420/4520 17.3.1 REGISTERS SSPSR is the shift register used for shifting data in or out. SSPBUF is the buffer register to which data bytes are written to or read from. The MSSP module has four registers for SPI mode operation. These are: In receive operations, SSPSR and SSPBUF together create a double-buffered receiver. When SSPSR receives a complete byte, it is transferred to SSPBUF and the SSPIF interrupt is set. * MSSP Control Register 1 (SSPCON1) * MSSP Status Register (SSPSTAT) * Serial Receive/Transmit Buffer Register (SSPBUF) * MSSP Shift Register (SSPSR) - Not directly accessible During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF and SSPSR. SSPCON1 and SSPSTAT are the control and status registers in SPI mode operation. The SSPCON1 register is readable and writable. The lower 6 bits of the SSPSTAT are read-only. The upper two bits of the SSPSTAT are read/write. REGISTER 17-1: R/W-0 SMP SSPSTAT: MSSP STATUS REGISTER (SPI MODE) R/W-0 R-0 R-0 R-0 R-0 R-0 R-0 (1) D/A P S R/W UA BF CKE 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 SMP: Sample bit SPI Master mode: 1 = Input data sampled at end of data output time 0 = Input data sampled at middle of data output time SPI Slave mode: SMP must be cleared when SPI is used in Slave mode. bit 6 CKE: SPI Clock Select bit(1) 1 = Transmit occurs on transition from active to Idle clock state 0 = Transmit occurs on transition from Idle to active clock state bit 5 D/A: Data/Address bit Used in I2CTM mode only. bit 4 P: Stop bit Used in I2C mode only. This bit is cleared when the MSSP module is disabled, SSPEN is cleared. bit 3 S: Start bit Used in I2C mode only. bit 2 R/W: Read/Write Information bit Used in I2C mode only. bit 1 UA: Update Address bit Used in I2C mode only. bit 0 BF: Buffer Full Status bit (Receive mode only) 1 = Receive complete, SSPBUF is full 0 = Receive not complete, SSPBUF is empty Note 1: Polarity of clock state is set by the CKP bit (SSPCON1<4>). DS39631E-page 162 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 17-2: R/W-0 WCOL SSPCON1: MSSP CONTROL REGISTER 1 (SPI MODE) R/W-0 R/W-0 (1) (2) SSPOV SSPEN R/W-0 CKP R/W-0 SSPM3 (3) R/W-0 SSPM2 (3) R/W-0 SSPM1 (3) R/W-0 SSPM0(3) 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 WCOL: Write Collision Detect bit 1 = The SSPxBUF register is written while it is still transmitting the previous word (must be cleared in software) 0 = No collision bit 6 SSPOV: Receive Overflow Indicator bit(1) SPI Slave mode: 1 = A new byte is received while the SSPBUF register is still holding the previous data. In case of overflow, the data in SSPSR is lost. Overflow can only occur in Slave mode. The user must read the SSPBUF, even if only transmitting data, to avoid setting overflow (must be cleared in software). 0 = No overflow bit 5 SSPEN: Master Synchronous Serial Port Enable bit(2) 1 = Enables serial port and configures SCK, SDO, SDI and SS as serial port pins 0 = Disables serial port and configures these pins as I/O port pins bit 4 CKP: Clock Polarity Select bit 1 = Idle state for clock is a high level 0 = Idle state for clock is a low level bit 3-0 SSPM<3:0>: Master Synchronous Serial Port Mode Select bits(3) 0101 = SPI Slave mode, clock = SCK pin; SS pin control disabled; SS can be used as I/O pin 0100 = SPI Slave mode, clock = SCK pin; SS pin control enabled 0011 = SPI Master mode, clock = TMR2 output/2 0010 = SPI Master mode, clock = FOSC/64 0001 = SPI Master mode, clock = FOSC/16 0000 = SPI Master mode, clock = FOSC/4 Note 1: 2: 3: In Master mode, the overflow bit is not set since each new reception (and transmission) is initiated by writing to the SSPBUF register. When enabled, these pins must be properly configured as input or output. Bit combinations not specifically listed here are either reserved or implemented in I2CTM mode only. (c) 2008 Microchip Technology Inc. DS39631E-page 163 PIC18F2420/2520/4420/4520 17.3.2 OPERATION When initializing the SPI, several options need to be specified. This is done by programming the appropriate control bits (SSPCON1<5:0> and SSPSTAT<7:6>). These control bits allow the following to be specified: * * * * Master mode (SCK is the clock output) Slave mode (SCK is the clock input) Clock Polarity (Idle state of SCK) Data Input Sample Phase (middle or end of data output time) * Clock Edge (output data on rising/falling edge of SCK) * Clock Rate (Master mode only) * Slave Select mode (Slave mode only) The MSSP consists of a transmit/receive shift register (SSPSR) and a buffer register (SSPBUF). The SSPSR shifts the data in and out of the device, MSb first. The SSPBUF holds the data that was written to the SSPSR until the received data is ready. Once the 8 bits of data have been received, that byte is moved to the SSPBUF register. Then, the Buffer Full detect bit, BF (SSPSTAT<0>) and the interrupt flag bit, SSPIF, are set. This double-buffering of the received data (SSPBUF) allows the next byte to start reception before reading the data that was just received. Any write to the SSPBUF register during transmission/reception of data EXAMPLE 17-1: LOOP Note: will be ignored and the write collision detect bit, WCOL (SSPCON1<7>), will be set. User software must clear the WCOL bit so that it can be determined if the following write(s) to the SSPBUF register completed successfully. When the application software is expecting to receive valid data, the SSPBUF should be read before the next byte of data to transfer is written to the SSPBUF. The Buffer Full bit, BF (SSPSTAT<0>), indicates when SSPBUF has been loaded with the received data (transmission is complete). When the SSPBUF is read, the BF bit is cleared. This data may be irrelevant if the SPI is only a transmitter. Generally, the MSSP interrupt is used to determine when the transmission/reception has completed. The SSPBUF must be read and/or written. If the interrupt method is not going to be used, then software polling can be done to ensure that a write collision does not occur. Example 17-1 shows the loading of the SSPBUF (SSPSR) for data transmission. The SSPSR is not directly readable or writable and can only be accessed by addressing the SSPBUF register. Additionally, the MSSP Status register (SSPSTAT) indicates the various status conditions. Note: The SSPBUF register cannot be used with read-modify-write instructions such as BCF, BTFSC and COMF, etc. LOADING THE SSPBUF (SSPSR) REGISTER BTFSS BRA MOVF SSPSTAT, BF LOOP SSPBUF, W ;Has data been received (transmit complete)? ;No ;WREG reg = contents of SSPBUF MOVWF RXDATA ;Save in user RAM, if data is meaningful MOVF MOVWF TXDATA, W SSPBUF ;W reg = contents of TXDATA ;New data to xmit To avoid lost data in Master mode, a read of the SSPBUF must be performed to clear the Buffer Full (BF) detect bit (SSPSTAT<0>) between each transmission. DS39631E-page 164 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.3.3 ENABLING SPI I/O 17.3.4 To enable the serial port, MSSP Enable bit, SSPEN (SSPCON1<5>), must be set. To reset or reconfigure SPI mode, clear the SSPEN bit, reinitialize the SSPCON registers and then set the SSPEN bit. This configures the SDI, SDO, SCK and SS pins as serial port pins. For the pins to behave as the serial port function, some must have their data direction bits (in the TRIS register) appropriately programmed as follows: * SDI is automatically controlled by the SPI module * SDO must have TRISC<5> bit cleared * SCK (Master mode) must have TRISC<3> bit cleared * SCK (Slave mode) must have TRISC<3> bit set * SS must have TRISA<5> bit set TYPICAL CONNECTION Figure 17-2 shows a typical connection between two microcontrollers. The master controller (Processor 1) initiates the data transfer by sending the SCK signal. Data is shifted out of both shift registers on their programmed clock edge and latched on the opposite edge of the clock. Both processors should be programmed to the same Clock Polarity (CKP), then both controllers would send and receive data at the same time. Whether the data is meaningful (or dummy data) depends on the application software. This leads to three scenarios for data transmission: * Master sends data - Slave sends dummy data * Master sends data - Slave sends data * Master sends dummy data - Slave sends data Any serial port function that is not desired may be overridden by programming the corresponding data direction (TRIS) register to the opposite value. FIGURE 17-2: SPI MASTER/SLAVE CONNECTION SPI Master SSPM<3:0> = 00xxb SPI Slave SSPM<3:0> = 010xb SDO SDI Serial Input Buffer (SSPBUF) SDI Shift Register (SSPSR) MSb Serial Input Buffer (SSPBUF) LSb (c) 2008 Microchip Technology Inc. Shift Register (SSPSR) MSb SCK PROCESSOR 1 SDO Serial Clock LSb SCK PROCESSOR 2 DS39631E-page 165 PIC18F2420/2520/4420/4520 17.3.5 MASTER MODE The master can initiate the data transfer at any time because it controls the SCK. The master determines when the slave (Processor 2, Figure 17-2) is to broadcast data by the software protocol. In Master mode, the data is transmitted/received as soon as the SSPBUF register is written to. If the SPI is only going to receive, the SDO output could be disabled (programmed as an input). The SSPSR register will continue to shift in the signal present on the SDI pin at the programmed clock rate. As each byte is received, it will be loaded into the SSPBUF register as if a normal received byte (interrupts and status bits appropriately set). This could be useful in receiver applications as a "Line Activity Monitor" mode. FIGURE 17-3: The clock polarity is selected by appropriately programming the CKP bit (SSPCON1<4>). This, then, would give waveforms for SPI communication as shown in Figure 17-3, Figure 17-5 and Figure 17-6, where the MSB is transmitted first. In Master mode, the SPI clock rate (bit rate) is user-programmable to be one of the following: * * * * FOSC/4 (or TCY) FOSC/16 (or 4 * TCY) FOSC/64 (or 16 * TCY) Timer2 output/2 This allows a maximum data rate (at 40 MHz) of 10.00 Mbps. Figure 17-3 shows the waveforms for Master mode. When the CKE bit is set, the SDO data is valid before there is a clock edge on SCK. The change of the input sample is shown based on the state of the SMP bit. The time when the SSPBUF is loaded with the received data is shown. SPI MODE WAVEFORM (MASTER MODE) Write to SSPBUF SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0) 4 Clock Modes SCK (CKP = 0 CKE = 1) SCK (CKP = 1 CKE = 1) SDO (CKE = 0) bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 SDO (CKE = 1) bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 SDI (SMP = 0) bit 0 bit 7 Input Sample (SMP = 0) SDI (SMP = 1) bit 7 bit 0 Input Sample (SMP = 1) SSPIF SSPSR to SSPBUF DS39631E-page 166 Next Q4 Cycle after Q2 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.3.6 SLAVE MODE In Slave mode, the data is transmitted and received as the external clock pulses appear on SCK. When the last bit is latched, the SSPIF interrupt flag bit is set. Before enabling the module in SPI Slave mode, the clock line must match the proper Idle state. The clock line can be observed by reading the SCK pin. The Idle state is determined by the CKP bit (SSPCON1<4>). While in Slave mode, the external clock is supplied by the external clock source on the SCK pin. This external clock must meet the minimum high and low times as specified in the electrical specifications. While in Sleep mode, the slave can transmit/receive data. When a byte is received, the device will wake-up from Sleep. 17.3.7 SLAVE SELECT SYNCHRONIZATION The SS pin allows a Synchronous Slave mode. The SPI must be in Slave mode with SS pin control enabled (SSPCON1<3:0> = 04h). The pin must not be driven low for the SS pin to function as an input. The data latch FIGURE 17-4: must be high. When the SS pin is low, transmission and reception are enabled and the SDO pin is driven. When the SS pin goes high, the SDO pin is no longer driven, even if in the middle of a transmitted byte and becomes a floating output. External pull-up/pull-down resistors may be desirable depending on the application. Note 1: When the SPI is in Slave mode with SS pin control enabled (SSPCON<3:0> = 0100), the SPI module will reset if the SS pin is set to VDD. 2: If the SPI is used in Slave mode with CKE set, then the SS pin control must be enabled. When the SPI module resets, the bit counter is forced to `0'. This can be done by either forcing the SS pin to a high level or clearing the SSPEN bit. To emulate two-wire communication, the SDO pin can be connected to the SDI pin. When the SPI needs to operate as a receiver, the SDO pin can be configured as an input. This disables transmissions from the SDO. The SDI can always be left as an input (SDI function) since it cannot create a bus conflict. SLAVE SYNCHRONIZATION WAVEFORM SS SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0) Write to SSPBUF SDO SDI (SMP = 0) bit 7 bit 6 bit 7 bit 0 bit 0 bit 7 bit 7 Input Sample (SMP = 0) SSPIF Interrupt Flag SSPSR to SSPBUF (c) 2008 Microchip Technology Inc. Next Q4 Cycle after Q2 DS39631E-page 167 PIC18F2420/2520/4420/4520 FIGURE 17-5: SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 0) SS Optional SCK (CKP = 0 CKE = 0) SCK (CKP = 1 CKE = 0) Write to SSPBUF SDO SDI (SMP = 0) bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 bit 0 bit 7 Input Sample (SMP = 0) SSPIF Interrupt Flag Next Q4 Cycle after Q2 SSPSR to SSPBUF FIGURE 17-6: SPI MODE WAVEFORM (SLAVE MODE WITH CKE = 1) SS Not Optional SCK (CKP = 0 CKE = 1) SCK (CKP = 1 CKE = 1) Write to SSPBUF SDO bit 7 SDI (SMP = 0) bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0 bit 0 Input Sample (SMP = 0) SSPIF Interrupt Flag SSPSR to SSPBUF DS39631E-page 168 Next Q4 Cycle after Q2 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.3.8 OPERATION IN POWER-MANAGED MODES 17.3.9 In SPI Master mode, module clocks may be operating at a different speed than when in full-power mode; in the case of Sleep mode, all clocks are halted. In most Idle modes, a clock is provided to the peripherals. That clock should be from the primary clock source, the secondary clock (Timer1 oscillator at 32.768 kHz) or the INTOSC source. See Section 2.7 "Clock Sources and Oscillator Switching" for additional information. In most cases, the speed that the master clocks SPI data is not important; however, this should be evaluated for each system. If MSSP interrupts are enabled, they can wake the controller from Sleep mode, or one of the Idle modes, when the master completes sending data. If an exit from Sleep or Idle mode is not desired, MSSP interrupts should be disabled. If the Sleep mode is selected, all module clocks are halted and the transmission/reception will remain in that state until the devices wakes. After the device returns to Run mode, the module will resume transmitting and receiving data. EFFECTS OF A RESET A Reset disables the MSSP module and terminates the current transfer. 17.3.10 BUS MODE COMPATIBILITY Table 17-1 shows the compatibility between the standard SPI modes and the states of the CKP and CKE control bits. TABLE 17-1: SPI BUS MODES Control Bits State Standard SPI Mode Terminology CKP CKE 0, 0 0 1 0, 1 0 0 1, 0 1 1 1, 1 1 0 There is also an SMP bit which controls when the data is sampled. In SPI Slave mode, the SPI Transmit/Receive Shift register operates asynchronously to the device. This allows the device to be placed in any power-managed mode and data to be shifted into the SPI Transmit/ Receive Shift register. When all 8 bits have been received, the MSSP interrupt flag bit will be set, and if enabled, will wake the device. TABLE 17-2: Name REGISTERS ASSOCIATED WITH SPI OPERATION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 (2) TRISA6(2) PORTA Data Direction Register TRISA TRISA7 TRISC PORTC Data Direction Register SSPBUF MSSP Receive Buffer/Transmit Register 52 52 50 SSPCON1 WCOL SSPOV SSPEN CKP SSPM3 SSPM2 SSPM1 SSPM0 50 SSPSTAT SMP CKE D/A P S R/W UA BF 50 Legend: Shaded cells are not used by the MSSP in SPI mode. Note 1: These bits are unimplemented in 28-pin devices; always maintain these bits clear. 2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. (c) 2008 Microchip Technology Inc. DS39631E-page 169 PIC18F2420/2520/4420/4520 17.4 I2C Mode 17.4.1 The MSSP module in I 2C mode fully implements all master and slave functions (including general call support) and provides interrupts on Start and Stop bits in hardware to determine a free bus (multi-master function). The MSSP module implements the standard mode specifications, as well as 7-Bit and 10-Bit Addressing modes. Two pins are used for data transfer: * Serial clock (SCL) - RC3/SCK/SCL * Serial data (SDA) - RC4/SDI/SDA The user must configure these pins as inputs or outputs through the TRISC<4:3> bits. FIGURE 17-7: MSSP BLOCK DIAGRAM (I2C MODE) Internal Data Bus Read Write SSPBUF reg RC3/SCK/SCL Shift Clock MSb LSb Match Detect Addr Match SSPADD reg Start and Stop bit Detect DS39631E-page 170 The MSSP module has six registers for I2C operation. These are: * * * * MSSP Control Register 1 (SSPCON1) MSSP Control Register 2 (SSPCON2) MSSP Status Register (SSPSTAT) Serial Receive/Transmit Buffer Register (SSPBUF) * MSSP Shift Register (SSPSR) - Not directly accessible * MSSP Address Register (SSPADD) SSPCON1, SSPCON2 and SSPSTAT are the control and status registers in I2C mode operation. The SSPCON1 and SSPCON2 registers are readable and writable. The lower 6 bits of the SSPSTAT are read-only. The upper two bits of the SSPSTAT are read/write. SSPSR is the shift register used for shifting data in or out. SSPBUF is the buffer register to which data bytes are written to or read from. SSPADD register holds the slave device address when the MSSP is configured in I2C Slave mode. When the MSSP is configured in Master mode, the lower seven bits of SSPADD act as the Baud Rate Generator reload value. In receive operations, SSPSR and SSPBUF together create a double-buffered receiver. When SSPSR receives a complete byte, it is transferred to SSPBUF and the SSPIF interrupt is set. SSPSR reg RC4/SDI/ SDA REGISTERS During transmission, the SSPBUF is not doublebuffered. A write to SSPBUF will write to both SSPBUF and SSPSR. Set, Reset S, P bits (SSPSTAT reg) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 17-3: R/W-0 SSPSTAT: MSSP STATUS REGISTER (I2CTM MODE) R/W-0 SMP CKE R-0 R-0 R-0 D/A (1) (1) P S R-0 R/W (2,3) R-0 R-0 UA BF 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 SMP: Slew Rate Control bit In Master or Slave mode: 1 = Slew rate control disabled for Standard Speed mode (100 kHz and 1 MHz) 0 = Slew rate control enabled for High-Speed mode (400 kHz) bit 6 CKE: SMBus Select bit In Master or Slave mode: 1 = Enable SMBus specific inputs 0 = Disable SMBus specific inputs bit 5 D/A: Data/Address bit In Master mode: Reserved. In Slave mode: 1 = Indicates that the last byte received or transmitted was data 0 = Indicates that the last byte received or transmitted was address bit 4 P: Stop bit(1) 1 = Indicates that a Stop bit has been detected last 0 = Stop bit was not detected last bit 3 S: Start bit(1) 1 = Indicates that a Start bit has been detected last 0 = Start bit was not detected last bit 2 R/W: Read/Write Information bit (I2C mode only)(2,3) In Slave mode: 1 = Read 0 = Write In Master mode: 1 = Transmit is in progress 0 = Transmit is not in progress bit 1 UA: Update Address bit (10-Bit Slave mode only) 1 = Indicates that the user needs to update the address in the SSPADD register 0 = Address does not need to be updated bit 0 BF: Buffer Full Status bit In Transmit mode: 1 = SSPBUF is full 0 = SSPBUF is empty In Receive mode: 1 = SSPBUF is full (does not include the ACK and Stop bits) 0 = SSPBUF is empty (does not include the ACK and Stop bits) Note 1: 2: 3: This bit is cleared on Reset and when SSPEN is cleared. This bit holds the R/W bit information following the last address match. This bit is only valid from the address match to the next Start bit, Stop bit or not ACK bit. ORing this bit with SEN, RSEN, PEN, RCEN or ACKEN will indicate if the MSSP is in Active mode. (c) 2008 Microchip Technology Inc. DS39631E-page 171 PIC18F2420/2520/4420/4520 REGISTER 17-4: R/W-0 WCOL SSPCON1: MSSP CONTROL REGISTER 1 (I2CTM MODE) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 SSPOV SSPEN(1) CKP SSPM3 SSPM2 SSPM1 SSPM0 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 WCOL: Write Collision Detect bit In Master Transmit mode: 1 = A write to the SSPBUF register was attempted while the I2C conditions were not valid for a transmission to be started (must be cleared in software) 0 = No collision In Slave Transmit mode: 1 = The SSPBUF register is written while it is still transmitting the previous word (must be cleared in software) 0 = No collision In Receive mode (Master or Slave modes): This is a "don't care" bit. bit 6 SSPOV: Receive Overflow Indicator bit In Receive mode: 1 = A byte is received while the SSPBUF register is still holding the previous byte (must be cleared in software) 0 = No overflow In Transmit mode: This is a "don't care" bit in Transmit mode. bit 5 SSPEN: Master Synchronous Serial Port Enable bit(1) 1 = Enables the serial port and configures the SDA and SCL pins as the serial port pins 0 = Disables serial port and configures these pins as I/O port pins bit 4 CKP: SCK Release Control bit In Slave mode: 1 = Releases clock 0 = Holds clock low (clock stretch), used to ensure data setup time In Master mode: Unused in this mode. bit 3-0 SSPM<3:0>: Master Synchronous Serial Port Mode Select bits(2) 1111 = I2C Slave mode, 10-bit address with Start and Stop bit interrupts enabled 1110 = I2C Slave mode, 7-bit address with Start and Stop bit interrupts enabled 1011 = I2C Firmware Controlled Master mode (Slave Idle) 1000 = I2C Master mode, clock = FOSC/(4 * (SSPADD + 1)) 0111 = I2C Slave mode, 10-bit address 0110 = I2C Slave mode, 7-bit address Bit combinations not specifically listed here are either reserved or implemented in SPI mode only. Note 1: When enabled, the SDA and SCL pins must be properly configured as inputs or outputs. DS39631E-page 172 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 17-5: SSPCON2: MSSP CONTROL REGISTER 2 (I2CTM MODE) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 GCEN ACKSTAT ACKDT(2) ACKEN(1) RCEN(1) PEN(1) RSEN(1) SEN(1) 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 GCEN: General Call Enable bit (Slave mode only) 1 = Enables interrupt when a general call address (0000h) is received in the SSPSR 0 = General call address disabled. bit 6 ACKSTAT: Acknowledge Status bit (Master Transmit mode only) 1 = Acknowledge was not received from slave 0 = Acknowledge was received from slave bit 5 ACKDT: Acknowledge Data bit (Master Receive mode only)(2) 1 = Not Acknowledge 0 = Acknowledge bit 4 ACKEN: Acknowledge Sequence Enable bit (Master Receive mode only)(1) 1 = Initiates Acknowledge sequence on SDA and SCL pins and transmit ACKDT data bit. Automatically cleared by hardware. 0 = Acknowledge sequence Idle bit 3 RCEN: Receive Enable bit (Master mode only)(1) 1 = Enables Receive mode for I2C 0 = Receive Idle bit 2 PEN: Stop Condition Enable bit (Master mode only)(1) 1 = Initiates Stop condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Stop condition Idle bit 1 RSEN: Repeated Start Condition Enable bit (Master mode only)(1) 1 = Initiates Repeated Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Repeated Start condition Idle bit 0 SEN: Start Condition Enable/Stretch Enable bit(1) In Master mode: 1 = Initiates Start condition on SDA and SCL pins. Automatically cleared by hardware. 0 = Start condition Idle In Slave mode: 1 = Clock stretching is enabled for both slave transmit and slave receive (stretch enabled) 0 = Clock stretching is disabled Note 1: 2: For bits ACKEN, RCEN, PEN, RSEN, SEN: If the I2C module is not in the Idle mode, these bits may not be set (no spooling) and the SSPBUF may not be written (or writes to the SSPBUF are disabled). Value that will be transmitted when the user initiates an Acknowledge sequence at the end of a receive. (c) 2008 Microchip Technology Inc. DS39631E-page 173 PIC18F2420/2520/4420/4520 17.4.2 OPERATION The MSSP module functions are enabled by setting the MSSP Enable bit, SSPEN (SSPCON1<5>). The SSPCON1 register allows control of the I 2C operation. Four mode selection bits (SSPCON1<3:0>) allow one of the following I 2C modes to be selected: I2C Master mode, clock = (FOSC/4) x (SSPADD + 1) I 2C Slave mode (7-bit addressing) I 2C Slave mode (10-bit addressing) I 2C Slave mode (7-bit addressing) with Start and Stop bit interrupts enabled * I 2C Slave mode (10-bit addressing) with Start and Stop bit interrupts enabled * I 2C Firmware Controlled Master mode, slave is Idle * * * * Selection of any I 2C mode, with the SSPEN bit set, forces the SCL and SDA pins to be open-drain, provided these pins are programmed to inputs by setting the appropriate TRISC bits. To ensure proper operation of the module, pull-up resistors must be provided externally to the SCL and SDA pins. 17.4.3 SLAVE MODE In Slave mode, the SCL and SDA pins must be configured as inputs (TRISC<4:3> set). The MSSP module will override the input state with the output data when required (slave-transmitter). The I 2C Slave mode hardware will always generate an interrupt on an address match. Through the mode select bits, the user can also choose to interrupt on Start and Stop bits When an address is matched, or the data transfer after an address match is received, the hardware automatically will generate the Acknowledge (ACK) pulse and load the SSPBUF register with the received value currently in the SSPSR register. 17.4.3.1 Once the MSSP module has been enabled, it waits for a Start condition to occur. Following the Start condition, the 8 bits are shifted into the SSPSR register. All incoming bits are sampled with the rising edge of the clock (SCL) line. The value of register SSPSR<7:1> is compared to the value of the SSPADD register. The address is compared on the falling edge of the eighth clock (SCL) pulse. If the addresses match and the BF and SSPOV bits are clear, the following events occur: 1. 2. 3. 4. In this case, the SSPSR register value is not loaded into the SSPBUF, but bit, SSPIF (PIR1<3>), is set. The BF bit is cleared by reading the SSPBUF register, while bit SSPOV is cleared through software. The SSPSR register value is loaded into the SSPBUF register. The Buffer Full bit, BF, is set. An ACK pulse is generated. MSSP Interrupt Flag bit, SSPIF (PIR1<3>), is set (interrupt is generated, if enabled) on the falling edge of the ninth SCL pulse. In 10-Bit Addressing mode, two address bytes need to be received by the slave. The five Most Significant bits (MSbs) of the first address byte specify if this is a 10-bit address. Bit, R/W (SSPSTAT<2>), must specify a write so the slave device will receive the second address byte. For a 10-bit address, the first byte would equal `11110 A9 A8 0', where `A9' and `A8' are the two MSbs of the address. The sequence of events for 10-Bit Addressing mode is as follows, with steps 7 through 9 for the slave-transmitter: 1. 2. 3. 4. 5. Any combination of the following conditions will cause the MSSP module not to give this ACK pulse: * The Buffer Full bit, BF (SSPSTAT<0>), was set before the transfer was received. * The overflow bit, SSPOV (SSPCON2<6>), was set before the transfer was received. Addressing 6. 7. 8. 9. Receive first (high) byte of address (bits, SSPIF, BF and UA (SSPSTAT<1>), are set). Update the SSPADD register with second (low) byte of address (clears UA bit and releases the SCL line). Read the SSPBUF register (clears BF bit) and clear flag bit, SSPIF. Receive second (low) byte of address (bits, SSPIF, BF and UA, are set). Update the SSPADD register with the first (high) byte of address. If match releases SCL line, this will clear bit, UA. Read the SSPBUF register (clears BF bit) and clear flag bit, SSPIF. Receive Repeated Start condition. Receive first (high) byte of address (bits, SSPIF and BF, are set). Read the SSPBUF register (clears BF bit) and clear flag bit, SSPIF. The SCL clock input must have a minimum high and low for proper operation. The high and low times of the I2C specification, as well as the requirement of the MSSP module, are shown in timing parameter 100 and parameter 101. DS39631E-page 174 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.3.2 Reception When the R/W bit of the address byte is clear and an address match occurs, the R/W bit of the SSPSTAT register is cleared. The received address is loaded into the SSPBUF register and the SDA line is held low (ACK). When the address byte overflow condition exists, then the no Acknowledge (ACK) pulse is given. An overflow condition is defined as either bit, BF (SSPSTAT<0>), is set, or bit, SSPOV (SSPCON1<6>), is set. An MSSP interrupt is generated for each data transfer byte. Flag bit, SSPIF (PIR1<3>), must be cleared in software. The SSPSTAT register is used to determine the status of the byte. If SEN is enabled (SSPCON2<0> = 1), RC3/SCK/SCL will be held low (clock stretch) following each data transfer. The clock must be released by setting bit, CKP (SSPCON<4>). See Section 17.4.4 "Clock Stretching" for more details. 17.4.3.3 Transmission When the R/W bit of the incoming address byte is set and an address match occurs, the R/W bit of the SSPSTAT register is set. The received address is loaded into the SSPBUF register. The ACK pulse will be sent on the ninth bit and the RC3/SCK/SCL pin is held low regardless of SEN (see Section 17.4.4 "Clock Stretching" for more detail). By stretching the clock, the master will be unable to assert another clock pulse until the slave is done preparing the transmit data. The transmit data must be loaded into the SSPBUF register which also loads the SSPSR register. Then the RC3/SCK/SCL pin should be enabled by setting bit, CKP (SSPCON1<4>). The eight data bits are shifted out on the falling edge of the SCL input. This ensures that the SDA signal is valid during the SCL high time (Figure 17-9). The ACK pulse from the master-receiver is latched on the rising edge of the ninth SCL input pulse. If the SDA line is high (not ACK), then the data transfer is complete. In this case, when the ACK is latched by the slave, the slave logic is reset (resets SSPSTAT register) and the slave monitors for another occurrence of the Start bit. If the SDA line was low (ACK), the next transmit data must be loaded into the SSPBUF register. Again, the RC3/SCK/SCL pin must be enabled by setting bit, CKP. An MSSP interrupt is generated for each data transfer byte. The SSPIF bit must be cleared in software and the SSPSTAT register is used to determine the status of the byte. The SSPIF bit is set on the falling edge of the ninth clock pulse. (c) 2008 Microchip Technology Inc. DS39631E-page 175 DS39631E-page 176 2 A6 3 4 A4 5 A3 Receiving Address A5 6 A2 (CKP does not reset to `0' when SEN = 0) CKP (SSPCON1<4>) SSPOV (SSPCON1<6>) BF (SSPSTAT<0>) (PIR1<3>) SSPIF 1 SCL S A7 7 A1 8 9 ACK R/W = 0 1 D7 3 4 D4 5 D3 Receiving Data D5 Cleared in software SSPBUF is read 2 D6 6 D2 7 D1 8 D0 9 ACK 1 D7 2 D6 3 4 D4 5 D3 Receiving Data D5 6 D2 7 D1 8 D0 Bus master terminates transfer P SSPOV is set because SSPBUF is still full. ACK is not sent. 9 ACK FIGURE 17-8: SDA PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 7-BIT ADDRESSING) (c) 2008 Microchip Technology Inc. (c) 2008 Microchip Technology Inc. 1 CKP 2 A6 Data in sampled BF (SSPSTAT<0>) SSPIF (PIR1<3>) S A7 3 A5 4 A4 5 A3 6 A2 Receiving Address 7 A1 8 R/W = 1 9 ACK 4 D4 5 D3 Cleared in software 3 D5 6 D2 SSPBUF is written in software 2 D6 CKP is set in software Clear by reading SCL held low while CPU responds to SSPIF 1 D7 Transmitting Data 7 8 D0 9 ACK From SSPIF ISR D1 1 D7 4 D4 5 D3 6 D2 CKP is set in software 7 8 D0 9 ACK From SSPIF ISR D1 Transmitting Data Cleared in software 3 D5 SSPBUF is written in software 2 D6 P FIGURE 17-9: SCL SDA PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING (TRANSMISSION, 7-BIT ADDRESSING) DS39631E-page 177 DS39631E-page 178 2 1 3 1 4 1 5 0 7 A8 UA is set indicating that the SSPADD needs to be updated 8 9 (CKP does not reset to `0' when SEN = 0) CKP (SSPCON1<4>) UA (SSPSTAT<1>) SSPOV (SSPCON1<6>) 6 A9 SSPBUF is written with contents of SSPSR Cleared in software BF (SSPSTAT<0>) (PIR1<3>) SSPIF 1 SCL S 1 ACK R/W = 0 A7 2 4 A4 5 A3 6 A2 8 9 A0 ACK UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with low byte of address 7 A1 Cleared in software 3 A5 Dummy read of SSPBUF to clear BF flag 1 A6 Receive Second Byte of Address 1 D7 4 5 6 Cleared in software 3 7 8 9 1 2 4 5 6 Cleared in software 3 D3 D2 Receive Data Byte D1 D0 ACK D7 D6 D5 D4 Cleared by hardware when SSPADD is updated with high byte of address 2 D3 D2 Receive Data Byte D6 D5 D4 Clock is held low until update of SSPADD has taken place 7 8 D1 D0 9 P Bus master terminates transfer SSPOV is set because SSPBUF is still full. ACK is not sent. ACK FIGURE 17-10: SDA Receive First Byte of Address Clock is held low until update of SSPADD has taken place PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING WITH SEN = 0 (RECEPTION, 10-BIT ADDRESSING) (c) 2008 Microchip Technology Inc. (c) 2008 Microchip Technology Inc. 2 CKP (SSPCON1<4>) UA (SSPSTAT<1>) BF (SSPSTAT<0>) (PIR1<3>) SSPIF 1 S SCL 1 4 1 5 0 6 7 A9 A8 8 UA is set indicating that the SSPADD needs to be updated SSPBUF is written with contents of SSPSR 3 1 Receive First Byte of Address 1 9 ACK 1 3 4 5 Cleared in software 2 7 UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with low byte of address 6 A6 A5 A4 A3 A2 A1 8 A0 Receive Second Byte of Address Dummy read of SSPBUF to clear BF flag A7 9 ACK 2 3 1 4 1 Cleared in software 1 1 5 0 6 8 9 ACK R/W=1 1 2 4 5 6 CKP is set in software 9 P Completion of data transmission clears BF flag 8 ACK Bus master terminates transfer CKP is automatically cleared in hardware, holding SCL low 7 D4 D3 D2 D1 D0 Cleared in software 3 D7 D6 D5 Transmitting Data Byte Clock is held low until CKP is set to `1' Write of SSPBUF BF flag is clear initiates transmit at the end of the third address sequence 7 A9 A8 Cleared by hardware when SSPADD is updated with high byte of address. Dummy read of SSPBUF to clear BF flag Sr 1 Receive First Byte of Address Clock is held low until update of SSPADD has taken place FIGURE 17-11: SDA R/W = 0 Clock is held low until update of SSPADD has taken place PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING (TRANSMISSION, 10-BIT ADDRESSING) DS39631E-page 179 PIC18F2420/2520/4420/4520 17.4.4 CLOCK STRETCHING Both 7-Bit and 10-Bit Slave modes implement automatic clock stretching during a transmit sequence. The SEN bit (SSPCON2<0>) allows clock stretching to be enabled during receives. Setting SEN will cause the SCL pin to be held low at the end of each data receive sequence. 17.4.4.1 Clock Stretching for 7-Bit Slave Receive Mode (SEN = 1) In 7-Bit Slave Receive mode, on the falling edge of the ninth clock at the end of the ACK sequence if the BF bit is set, the CKP bit in the SSPCON1 register is automatically cleared, forcing the SCL output to be held low. The CKP being cleared to `0' will assert the SCL line low. The CKP bit must be set in the user's Interrupt Service Routine (ISR) before reception is allowed to continue. By holding the SCL line low, the user has time to service the ISR and read the contents of the SSPBUF before the master device can initiate another receive sequence. This will prevent buffer overruns from occurring (see Figure 17-13). Note 1: If the user reads the contents of the SSPBUF before the falling edge of the ninth clock, thus clearing the BF bit, the CKP bit will not be cleared and clock stretching will not occur. 2: The CKP bit can be set in software regardless of the state of the BF bit. The user should be careful to clear the BF bit in the ISR before the next receive sequence in order to prevent an overflow condition. 17.4.4.2 17.4.4.3 Clock Stretching for 7-Bit Slave Transmit Mode 7-Bit Slave Transmit mode implements clock stretching by clearing the CKP bit after the falling edge of the ninth clock if the BF bit is clear. This occurs regardless of the state of the SEN bit. The user's ISR must set the CKP bit before transmission is allowed to continue. By holding the SCL line low, the user has time to service the ISR and load the contents of the SSPBUF before the master device can initiate another transmit sequence (see Figure 17-9). Note 1: If the user loads the contents of SSPBUF, setting the BF bit before the falling edge of the ninth clock, the CKP bit will not be cleared and clock stretching will not occur. 2: The CKP bit can be set in software regardless of the state of the BF bit. 17.4.4.4 Clock Stretching for 10-Bit Slave Transmit Mode In 10-Bit Slave Transmit mode, clock stretching is controlled during the first two address sequences by the state of the UA bit, just as it is in 10-Bit Slave Receive mode. The first two addresses are followed by a third address sequence which contains the high-order bits of the 10-bit address and the R/W bit set to `1'. After the third address sequence is performed, the UA bit is not set, the module is now configured in Transmit mode and clock stretching is controlled by the BF flag as in 7-Bit Slave Transmit mode (see Figure 17-11). Clock Stretching for 10-Bit Slave Receive Mode (SEN = 1) In 10-Bit Slave Receive mode during the address sequence, clock stretching automatically takes place but CKP is not cleared. During this time, if the UA bit is set after the ninth clock, clock stretching is initiated. The UA bit is set after receiving the upper byte of the 10-bit address and following the receive of the second byte of the 10-bit address with the R/W bit cleared to `0'. The release of the clock line occurs upon updating SSPADD. Clock stretching will occur on each data receive sequence as described in 7-bit mode. Note: If the user polls the UA bit and clears it by updating the SSPADD register before the falling edge of the ninth clock occurs and if the user hasn't cleared the BF bit by reading the SSPBUF register before that time, then the CKP bit will still NOT be asserted low. Clock stretching on the basis of the state of the BF bit only occurs during a data sequence, not an address sequence. DS39631E-page 180 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.4.5 Clock Synchronization and the CKP bit When the CKP bit is cleared, the SCL output is forced to `0'. However, clearing the CKP bit will not assert the SCL output low until the SCL output is already sampled low. Therefore, the CKP bit will not assert the SCL line until an external I2C master device has FIGURE 17-12: already asserted the SCL line. The SCL output will remain low until the CKP bit is set and all other devices on the I2C bus have deasserted SCL. This ensures that a write to the CKP bit will not violate the minimum high time requirement for SCL (see Figure 17-12). CLOCK SYNCHRONIZATION TIMING Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 SDA DX DX - 1 SCL CKP Master device asserts clock Master device deasserts clock WR SSPCONx (c) 2008 Microchip Technology Inc. DS39631E-page 181 DS39631E-page 182 CKP (SSPCON1<4>) SSPOV (SSPCON1<6>) BF (SSPSTAT<0>) (PIR1<3>) SSPIF 1 SCL S A7 2 A6 3 4 A4 5 A3 6 A2 Receiving Address A5 7 A1 8 9 ACK R/W = 0 3 4 D4 5 D3 Receiving Data D5 Cleared in software 2 D6 If BF is cleared prior to the falling edge of the 9th clock, CKP will not be reset to `0' and no clock stretching will occur SSPBUF is read 1 D7 6 D2 7 D1 9 ACK 1 D7 BF is set after falling edge of the 9th clock, CKP is reset to `0' and clock stretching occurs 8 D0 3 4 D4 5 D3 Receiving Data D5 CKP written to `1' in software 2 D6 Clock is held low until CKP is set to `1' 6 D2 7 D1 8 D0 Bus master terminates transfer P SSPOV is set because SSPBUF is still full. ACK is not sent. 9 ACK Clock is not held low because ACK = 1 FIGURE 17-13: SDA Clock is not held low because buffer full bit is clear prior to falling edge of 9th clock PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 7-BIT ADDRESSING) (c) 2008 Microchip Technology Inc. (c) 2008 Microchip Technology Inc. 2 1 3 1 4 1 5 0 CKP (SSPCON1<4>) UA (SSPSTAT<1>) SSPOV (SSPCON1<6>) 6 7 A9 A8 8 UA is set indicating that the SSPADD needs to be updated SSPBUF is written with contents of SSPSR Cleared in software BF (SSPSTAT<0>) (PIR1<3>) SSPIF 1 SCL S 1 9 ACK R/W = 0 A7 2 4 A4 5 A3 6 A2 Cleared in software 3 A5 7 A1 8 A0 Note: An update of the SSPADD register before the falling edge of the ninth clock will have no effect on UA and UA will remain set. UA is set indicating that SSPADD needs to be updated Cleared by hardware when SSPADD is updated with low byte of address after falling edge of ninth clock Dummy read of SSPBUF to clear BF flag 1 A6 Receive Second Byte of Address 9 ACK 2 4 5 6 Cleared in software 3 D3 D2 7 8 Note: An update of the SSPADD register before the falling edge of the ninth clock will have no effect on UA and UA will remain set. 9 ACK 1 4 5 6 Cleared in software 3 CKP written to `1' in software 2 D3 D2 Receive Data Byte D7 D6 D5 D4 Clock is held low until CKP is set to `1' D1 D0 Cleared by hardware when SSPADD is updated with high byte of address after falling edge of ninth clock Dummy read of SSPBUF to clear BF flag 1 D7 D6 D5 D4 Receive Data Byte Clock is held low until update of SSPADD has taken place 7 8 9 Bus master terminates transfer P SSPOV is set because SSPBUF is still full. ACK is not sent. D1 D0 ACK Clock is not held low because ACK = 1 FIGURE 17-14: SDA Receive First Byte of Address Clock is held low until update of SSPADD has taken place PIC18F2420/2520/4420/4520 I2CTM SLAVE MODE TIMING WITH SEN = 1 (RECEPTION, 10-BIT ADDRESSING) DS39631E-page 183 PIC18F2420/2520/4420/4520 17.4.5 GENERAL CALL ADDRESS SUPPORT If the general call address matches, the SSPSR is transferred to the SSPBUF, the BF flag bit is set (eighth bit) and on the falling edge of the ninth bit (ACK bit), the SSPIF interrupt flag bit is set. The addressing procedure for the I2C bus is such that the first byte after the Start condition usually determines which device will be the slave addressed by the master. The exception is the general call address which can address all devices. When this address is used, all devices should, in theory, respond with an Acknowledge. When the interrupt is serviced, the source for the interrupt can be checked by reading the contents of the SSPBUF. The value can be used to determine if the address was device specific or a general call address. In 10-bit mode, the SSPADD is required to be updated for the second half of the address to match and the UA bit is set (SSPSTAT<1>). If the general call address is sampled when the GCEN bit is set, while the slave is configured in 10-Bit Addressing mode, then the second half of the address is not necessary, the UA bit will not be set and the slave will begin receiving data after the Acknowledge (Figure 17-15). The general call address is one of eight addresses reserved for specific purposes by the I2C protocol. It consists of all `0's with R/W = 0. The general call address is recognized when the General Call Enable bit, GCEN, is enabled (SSPCON2<7> is set). Following a Start bit detect, 8 bits are shifted into the SSPSR and the address is compared against the SSPADD. It is also compared to the general call address and fixed in hardware. FIGURE 17-15: SLAVE MODE GENERAL CALL ADDRESS SEQUENCE (7 OR 10-BIT ADDRESSING MODE) Address is compared to General Call Address after ACK, set interrupt R/W = 0 ACK D7 General Call Address SDA SCL S 1 2 3 4 5 6 7 8 9 1 Receiving Data ACK D6 D5 D4 D3 D2 D1 D0 2 3 4 5 6 7 8 9 SSPIF BF (SSPSTAT<0>) Cleared in software SSPBUF is read SSPOV (SSPCON1<6>) `0' GCEN (SSPCON2<7>) `1' DS39631E-page 184 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 MASTER MODE Note: Master mode is enabled by setting and clearing the appropriate SSPM bits in SSPCON1 and by setting the SSPEN bit. In Master mode, the SCL and SDA lines are manipulated by the MSSP hardware. Master mode of operation is supported by interrupt generation on the detection of the Start and Stop conditions. The Stop (P) and Start (S) bits are cleared from a Reset or when the MSSP module is disabled. Control of the I 2C bus may be taken when the P bit is set, or the bus is Idle, with both the S and P bits clear. The following events will cause the MSSP Interrupt Flag bit, SSPIF, to be set (MSSP interrupt, if enabled): In Firmware Controlled Master mode, user code conducts all I 2C bus operations based on Start and Stop bit conditions. * * * * * Once Master mode is enabled, the user has six options. 1. 2. 3. 4. 5. 6. Assert a Start condition on SDA and SCL. Assert a Repeated Start condition on SDA and SCL. Write to the SSPBUF register initiating transmission of data/address. Configure the I2C port to receive data. Generate an Acknowledge condition at the end of a received byte of data. Generate a Stop condition on SDA and SCL. FIGURE 17-16: The MSSP module, when configured in I2C Master mode, does not allow queueing of events. For instance, the user is not allowed to initiate a Start condition and immediately write the SSPBUF register to initiate transmission before the Start condition is complete. In this case, the SSPBUF will not be written to and the WCOL bit will be set, indicating that a write to the SSPBUF did not occur. Start condition Stop condition Data transfer byte transmitted/received Acknowledge transmit Repeated Start MSSP BLOCK DIAGRAM (I2CTM MASTER MODE) Internal Data Bus Read SSPM<3:0> SSPADD<6:0> Write SSPBUF SDA Baud Rate Generator Shift Clock SDA In SCL In Bus Collision (c) 2008 Microchip Technology Inc. LSb Start bit, Stop bit, Acknowledge Generate Start bit Detect Stop bit Detect Write Collision Detect Clock Arbitration State Counter for end of XMIT/RCV Clock Cntl SCL Receive Enable SSPSR MSb Clock Arbitrate/WCOL Detect (hold off clock source) 17.4.6 Set/Reset, S, P, WCOL (SSPSTAT); Set SSPIF, BCLIF; Reset ACKSTAT, PEN (SSPCON2) DS39631E-page 185 PIC18F2420/2520/4420/4520 17.4.6.1 I2C Master Mode Operation The master device generates all of the serial clock pulses and the Start and Stop conditions. A transfer is ended with a Stop condition or with a Repeated Start condition. Since the Repeated Start condition is also the beginning of the next serial transfer, the I2C bus will not be released. In Master Transmitter mode, serial data is output through SDA, while SCL outputs the serial clock. The first byte transmitted contains the slave address of the receiving device (7 bits) and the Read/Write (R/W) bit. In this case, the R/W bit will be logic `0'. Serial data is transmitted 8 bits at a time. After each byte is transmitted, an Acknowledge bit is received. Start and Stop conditions are output to indicate the beginning and the end of a serial transfer. In Master Receive mode, the first byte transmitted contains the slave address of the transmitting device (7 bits) and the R/W bit. In this case, the R/W bit will be logic `1'. Thus, the first byte transmitted is a 7-bit slave address followed by a `1' to indicate the receive bit. Serial data is received via SDA, while SCL outputs the serial clock. Serial data is received 8 bits at a time. After each byte is received, an Acknowledge bit is transmitted. Start and Stop conditions indicate the beginning and end of transmission. The Baud Rate Generator used for the SPI mode operation is used to set the SCL clock frequency for either 100 kHz, 400 kHz or 1 MHz I2C operation. See Section 17.4.7 "Baud Rate" for more detail. DS39631E-page 186 A typical transmit sequence would go as follows: 1. The user generates a Start condition by setting the Start Enable bit, SEN (SSPCON2<0>). 2. SSPIF is set. The MSSP module will wait the required start time before any other operation takes place. 3. The user loads the SSPBUF with the slave address to transmit. 4. Address is shifted out the SDA pin until all 8 bits are transmitted. 5. The MSSP module shifts in the ACK bit from the slave device and writes its value into the SSPCON2 register (SSPCON2<6>). 6. The MSSP module generates an interrupt at the end of the ninth clock cycle by setting the SSPIF bit. 7. The user loads the SSPBUF with eight bits of data. 8. Data is shifted out the SDA pin until all 8 bits are transmitted. 9. The MSSP module shifts in the ACK bit from the slave device and writes its value into the SSPCON2 register (SSPCON2<6>). 10. The MSSP module generates an interrupt at the end of the ninth clock cycle by setting the SSPIF bit. 11. The user generates a Stop condition by setting the Stop Enable bit, PEN (SSPCON2<2>). 12. Interrupt is generated once the Stop condition is complete. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.7 BAUD RATE 2 In I C Master mode, the Baud Rate Generator (BRG) reload value is placed in the lower 7 bits of the SSPADD register (Figure 17-17). When a write occurs to SSPBUF, the Baud Rate Generator will automatically begin counting. The BRG counts down to 0 and stops until another reload has taken place. The BRG count is decremented twice per instruction cycle (TCY) on the Q2 and Q4 clocks. In I2C Master mode, the BRG is reloaded automatically. FIGURE 17-17: Once the given operation is complete (i.e., transmission of the last data bit is followed by ACK), the internal clock will automatically stop counting and the SCL pin will remain in its last state. Table 17-3 demonstrates clock rates based on instruction cycles and the BRG value loaded into SSPADD. BAUD RATE GENERATOR BLOCK DIAGRAM SSPM<3:0> SSPM<3:0> Reload SCL Control CLKO TABLE 17-3: Note 1: SSPADD<6:0> Reload BRG Down Counter FOSC/4 I2CTM CLOCK RATE W/BRG FCY FCY * 2 BRG Value FSCL (2 Rollovers of BRG) 10 MHz 20 MHz 18h 400 kHz(1) 10 MHz 20 MHz 1Fh 312.5 kHz 10 MHz 20 MHz 63h 100 kHz 4 MHz 8 MHz 09h 400 kHz(1) 4 MHz 8 MHz 0Ch 308 kHz 4 MHz 8 MHz 27h 100 kHz 1 MHz 2 MHz 02h 333 kHz(1) 1 MHz 2 MHz 09h 100 kHz 1 MHz 2 MHz 00h 1 MHz(1) The I2C interface does not conform to the 400 kHz I2C specification (which applies to rates greater than 100 kHz) in all details, but may be used with care where higher rates are required by the application. (c) 2008 Microchip Technology Inc. DS39631E-page 187 PIC18F2420/2520/4420/4520 17.4.7.1 Clock Arbitration Clock arbitration occurs when the master, during any receive, transmit or Repeated Start/Stop condition, deasserts the SCL pin (SCL allowed to float high). When the SCL pin is allowed to float high, the Baud Rate Generator (BRG) is suspended from counting until the SCL pin is actually sampled high. When the FIGURE 17-18: SCL pin is sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and begins counting. This ensures that the SCL high time will always be at least one BRG rollover count in the event that the clock is held low by an external device (Figure 17-18). BAUD RATE GENERATOR TIMING WITH CLOCK ARBITRATION SDA DX DX - 1 SCL deasserted but slave holds SCL low (clock arbitration) SCL allowed to transition high SCL BRG decrements on Q2 and Q4 cycles BRG Value 03h 02h 01h 00h (hold off) 03h 02h SCL is sampled high, reload takes place and BRG starts its count BRG Reload DS39631E-page 188 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.8 I2C MASTER MODE START CONDITION TIMING Note: To initiate a Start condition, the user sets the Start Enable bit, SEN (SSPCON2<0>). If the SDA and SCL pins are sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and starts its count. If SCL and SDA are both sampled high when the Baud Rate Generator times out (TBRG), the SDA pin is driven low. The action of the SDA being driven low while SCL is high is the Start condition and causes the S bit (SSPSTAT<3>) to be set. Following this, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and resumes its count. When the Baud Rate Generator times out (TBRG), the SEN bit (SSPCON2<0>) will be automatically cleared by hardware; the Baud Rate Generator is suspended, leaving the SDA line held low and the Start condition is complete. FIGURE 17-19: 17.4.8.1 If, at the beginning of the Start condition, the SDA and SCL pins are already sampled low, or if during the Start condition, the SCL line is sampled low before the SDA line is driven low, a bus collision occurs, the Bus Collision Interrupt Flag, BCLIF, is set, the Start condition is aborted and the I2C module is reset into its Idle state. WCOL Status Flag If the user writes the SSPBUF when a Start sequence is in progress, the WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). Note: Because queueing of events is not allowed, writing to the lower 5 bits of SSPCON2 is disabled until the Start condition is complete. FIRST START BIT TIMING Write to SEN bit occurs here Set S bit (SSPSTAT<3>) SDA = 1, SCL = 1 TBRG At completion of Start bit, hardware clears SEN bit and sets SSPIF bit TBRG Write to SSPBUF occurs here 1st bit SDA 2nd bit TBRG SCL TBRG S (c) 2008 Microchip Technology Inc. DS39631E-page 189 PIC18F2420/2520/4420/4520 17.4.9 I2C MASTER MODE REPEATED START CONDITION TIMING Note 1: If RSEN is programmed while any other event is in progress, it will not take effect. A Repeated Start condition occurs when the RSEN bit (SSPCON2<1>) is programmed high and the I2C logic module is in the Idle state. When the RSEN bit is set, the SCL pin is asserted low. When the SCL pin is sampled low, the Baud Rate Generator is loaded with the contents of SSPADD<5:0> and begins counting. The SDA pin is released (brought high) for one Baud Rate Generator count (TBRG). When the Baud Rate Generator times out, if SDA is sampled high, the SCL pin will be deasserted (brought high). When SCL is sampled high, the Baud Rate Generator is reloaded with the contents of SSPADD<6:0> and begins counting. SDA and SCL must be sampled high for one TBRG. This action is then followed by assertion of the SDA pin (SDA = 0) for one TBRG while SCL is high. Following this, the RSEN bit (SSPCON2<1>) will be automatically cleared and the Baud Rate Generator will not be reloaded, leaving the SDA pin held low. As soon as a Start condition is detected on the SDA and SCL pins, the S bit (SSPSTAT<3>) will be set. The SSPIF bit will not be set until the Baud Rate Generator has timed out. 2: A bus collision during the Repeated Start condition occurs if: * SDA is sampled low when SCL goes from low-to-high. * SCL goes low before SDA is asserted low. This may indicate that another master is attempting to transmit a data `1'. Immediately following the SSPIF bit getting set, the user may write the SSPBUF with the 7-bit address in 7-bit mode or the default first address in 10-bit mode. After the first eight bits are transmitted and an ACK is received, the user may then transmit an additional eight bits of address (10-bit mode) or eight bits of data (7-bit mode). 17.4.9.1 WCOL Status Flag If the user writes the SSPBUF when a Repeated Start sequence is in progress, the WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). Because queueing of events is not allowed, writing of the lower 5 bits of SSPCON2 is disabled until the Repeated Start condition is complete. Note: FIGURE 17-20: REPEATED START CONDITION WAVEFORM Write to SSPCON2 occurs here. SDA = 1, SCL (no change). S bit set by hardware SDA = 1, SCL = 1 TBRG TBRG At completion of Start bit, hardware clears RSEN bit and sets SSPIF TBRG 1st bit SDA RSEN bit set by hardware on falling edge of ninth clock, end of Xmit Write to SSPBUF occurs here TBRG SCL TBRG Sr = Repeated Start DS39631E-page 190 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.10 I2C MASTER MODE TRANSMISSION Transmission of a data byte, a 7-bit address or the other half of a 10-bit address is accomplished by simply writing a value to the SSPBUF register. This action will set the Buffer Full flag bit, BF, and allow the Baud Rate Generator to begin counting and start the next transmission. Each bit of address/data will be shifted out onto the SDA pin after the falling edge of SCL is asserted (see data hold time specification parameter 106). SCL is held low for one Baud Rate Generator rollover count (TBRG). Data should be valid before SCL is released high (see data setup time specification parameter 107). When the SCL pin is released high, it is held that way for TBRG. The data on the SDA pin must remain stable for that duration and some hold time after the next falling edge of SCL. After the eighth bit is shifted out (the falling edge of the eighth clock), the BF flag is cleared and the master releases SDA. This allows the slave device being addressed to respond with an ACK bit during the ninth bit time if an address match occurred, or if data was received properly. The status of ACK is written into the ACKDT bit on the falling edge of the ninth clock. If the master receives an Acknowledge, the Acknowledge Status bit, ACKSTAT, is cleared. If not, the bit is set. After the ninth clock, the SSPIF bit is set and the master clock (Baud Rate Generator) is suspended until the next data byte is loaded into the SSPBUF, leaving SCL low and SDA unchanged (Figure 17-21). After the write to the SSPBUF, each bit of the address will be shifted out on the falling edge of SCL until all seven address bits and the R/W bit are completed. On the falling edge of the eighth clock, the master will deassert the SDA pin, allowing the slave to respond with an Acknowledge. On the falling edge of the ninth clock, the master will sample the SDA pin to see if the address was recognized by a slave. The status of the ACK bit is loaded into the ACKSTAT status bit (SSPCON2<6>). Following the falling edge of the ninth clock transmission of the address, the SSPIF is set, the BF flag is cleared and the Baud Rate Generator is turned off until another write to the SSPBUF takes place, holding SCL low and allowing SDA to float. 17.4.10.1 BF Status Flag 17.4.10.3 ACKSTAT Status Flag In Transmit mode, the ACKSTAT bit (SSPCON2<6>) is cleared when the slave has sent an Acknowledge (ACK = 0) and is set when the slave does not Acknowledge (ACK = 1). A slave sends an Acknowledge when it has recognized its address (including a general call), or when the slave has properly received its data. 17.4.11 I2C MASTER MODE RECEPTION Master mode reception is enabled by programming the Receive Enable bit, RCEN (SSPCON2<3>). Note: The MSSP module must be in an Idle state before the RCEN bit is set or the RCEN bit will be disregarded. The Baud Rate Generator begins counting and on each rollover, the state of the SCL pin changes (high-to-low/ low-to-high) and data is shifted into the SSPSR. After the falling edge of the eighth clock, the receive enable flag is automatically cleared, the contents of the SSPSR are loaded into the SSPBUF, the BF flag bit is set, the SSPIF flag bit is set and the Baud Rate Generator is suspended from counting, holding SCL low. The MSSP is now in Idle state awaiting the next command. When the buffer is read by the CPU, the BF flag bit is automatically cleared. The user can then send an Acknowledge bit at the end of reception by setting the Acknowledge Sequence Enable bit, ACKEN (SSPCON2<4>). 17.4.11.1 BF Status Flag In receive operation, the BF bit is set when an address or data byte is loaded into SSPBUF from SSPSR. It is cleared when the SSPBUF register is read. 17.4.11.2 SSPOV Status Flag In receive operation, the SSPOV bit is set when 8 bits are received into the SSPSR and the BF flag bit is already set from a previous reception. 17.4.11.3 WCOL Status Flag If the user writes the SSPBUF when a receive is already in progress (i.e., SSPSR is still shifting in a data byte), the WCOL bit is set and the contents of the buffer are unchanged (the write doesn't occur). In Transmit mode, the BF bit (SSPSTAT<0>) is set when the CPU writes to SSPBUF and is cleared when all 8 bits are shifted out. 17.4.10.2 WCOL Status Flag If the user writes the SSPBUF when a transmit is already in progress (i.e., SSPSR is still shifting out a data byte), the WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). WCOL must be cleared in software. (c) 2008 Microchip Technology Inc. DS39631E-page 191 DS39631E-page 192 S R/W PEN SEN BF (SSPSTAT<0>) SSPIF SCL SDA A6 A5 A4 A3 A2 A1 3 4 5 Cleared in software 2 6 7 8 9 After Start condition, SEN cleared by hardware SSPBUF written 1 D7 1 SCL held low while CPU responds to SSPIF ACK = `0' R/W = 0 SSPBUF written with 7-bit address and R/W start transmit A7 Transmit Address to Slave 3 D5 4 D4 5 D3 6 D2 7 D1 8 D0 SSPBUF is written in software Cleared in software service routine from MSSP interrupt 2 D6 Transmitting Data or Second Half of 10-Bit Address From slave, clear ACKSTAT bit SSPCON2<6> P Cleared in software 9 ACK ACKSTAT in SSPCON2 = 1 FIGURE 17-21: SEN = 0 Write SSPCON2<0> SEN = 1 Start condition begins PIC18F2420/2520/4420/4520 I 2C MASTER MODE WAVEFORM (TRANSMISSION, 7 OR 10-BIT ADDRESSING) (c) 2008 Microchip Technology Inc. (c) 2008 Microchip Technology Inc. S ACKEN SSPOV BF (SSPSTAT<0>) SDA = 0, SCL = 1 while CPU responds to SSPIF SSPIF SCL SDA 1 A7 2 4 5 Cleared in software 3 6 A6 A5 A4 A3 A2 Transmit Address to Slave 7 A1 8 9 R/W = 0 ACK ACK from Slave 2 3 5 6 7 8 D0 9 ACK 2 3 4 5 6 7 Cleared in software Set SSPIF interrupt at end of Acknowledge sequence Data shifted in on falling edge of CLK 1 D7 D6 D5 D4 D3 D2 D1 Cleared in software Set SSPIF at end of receive 9 ACK is not sent ACK Bus master terminates transfer Set P bit (SSPSTAT<4>) and SSPIF Set SSPIF interrupt at end of Acknowledge sequence P PEN bit = 1 written here SSPOV is set because SSPBUF is still full 8 D0 RCEN cleared automatically Set ACKEN, start Acknowledge sequence SDA = ACKDT = 1 Receiving Data from Slave RCEN = 1, start next receive ACK from Master SDA = ACKDT = 0 Last bit is shifted into SSPSR and contents are unloaded into SSPBUF Cleared in software Set SSPIF interrupt at end of receive 4 Cleared in software 1 D7 D6 D5 D4 D3 D2 D1 Receiving Data from Slave RCEN cleared automatically Master configured as a receiver by programming SSPCON2<3> (RCEN = 1) FIGURE 17-22: SEN = 0 Write to SSPBUF occurs here, start XMIT Write to SSPCON2<0> (SEN = 1), begin Start condition Write to SSPCON2<4> to start Acknowledge sequence SDA = ACKDT (SSPCON2<5>) = 0 PIC18F2420/2520/4420/4520 I 2C MASTER MODE WAVEFORM (RECEPTION, 7-BIT ADDRESSING) DS39631E-page 193 PIC18F2420/2520/4420/4520 17.4.12 ACKNOWLEDGE SEQUENCE TIMING 17.4.13 A Stop bit is asserted on the SDA pin at the end of a receive/transmit by setting the Stop Sequence Enable bit, PEN (SSPCON2<2>). At the end of a receive/ transmit, the SCL line is held low after the falling edge of the ninth clock. When the PEN bit is set, the master will assert the SDA line low. When the SDA line is sampled low, the Baud Rate Generator is reloaded and counts down to 0. When the Baud Rate Generator times out, the SCL pin will be brought high and one TBRG (Baud Rate Generator rollover count) later, the SDA pin will be deasserted. When the SDA pin is sampled high while SCL is high, the P bit (SSPSTAT<4>) is set. A TBRG later, the PEN bit is cleared and the SSPIF bit is set (Figure 17-24). An Acknowledge sequence is enabled by setting the Acknowledge Sequence Enable bit, ACKEN (SSPCON2<4>). When this bit is set, the SCL pin is pulled low and the contents of the Acknowledge data bit are presented on the SDA pin. If the user wishes to generate an Acknowledge, then the ACKDT bit should be cleared. If not, the user should set the ACKDT bit before starting an Acknowledge sequence. The Baud Rate Generator then counts for one rollover period (TBRG) and the SCL pin is deasserted (pulled high). When the SCL pin is sampled high (clock arbitration), the Baud Rate Generator counts for TBRG. The SCL pin is then pulled low. Following this, the ACKEN bit is automatically cleared, the Baud Rate Generator is turned off and the MSSP module then goes into Idle mode (Figure 17-23). 17.4.12.1 17.4.13.1 WCOL Status Flag If the user writes the SSPBUF when a Stop sequence is in progress, then the WCOL bit is set and the contents of the buffer are unchanged (the write doesn't occur). WCOL Status Flag If the user writes the SSPBUF when an Acknowledge sequence is in progress, then WCOL is set and the contents of the buffer are unchanged (the write doesn't occur). FIGURE 17-23: STOP CONDITION TIMING ACKNOWLEDGE SEQUENCE WAVEFORM Acknowledge sequence starts here, write to SSPCON2 ACKEN = 1, ACKDT = 0 ACKEN automatically cleared TBRG TBRG SDA ACK D0 SCL 8 9 SSPIF SSPIF set at the end of receive Cleared in software Cleared in software SSPIF set at the end of Acknowledge sequence Note: TBRG = one Baud Rate Generator period. FIGURE 17-24: STOP CONDITION RECEIVE OR TRANSMIT MODE SCL = 1 for TBRG, followed by SDA = 1 for TBRG after SDA sampled high. P bit (SSPSTAT<4>) is set. Write to SSPCON2, set PEN PEN bit (SSPCON2<2>) is cleared by hardware and the SSPIF bit is set Falling edge of 9th clock TBRG SCL SDA ACK P TBRG TBRG TBRG SCL brought high after TBRG SDA asserted low before rising edge of clock to setup Stop condition Note: TBRG = one Baud Rate Generator period. DS39631E-page 194 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.14 SLEEP OPERATION 17.4.17 2 While in Sleep mode, the I C module can receive addresses or data and when an address match or complete byte transfer occurs, wake the processor from Sleep (if the MSSP interrupt is enabled). 17.4.15 EFFECTS OF A RESET A Reset disables the MSSP module and terminates the current transfer. 17.4.16 MULTI-MASTER MODE In Multi-Master mode, the interrupt generation on the detection of the Start and Stop conditions allows the determination of when the bus is free. The Stop (P) and Start (S) bits are cleared from a Reset or when the MSSP module is disabled. Control of the I 2C bus may be taken when the P bit (SSPSTAT<4>) is set, or the bus is Idle, with both the S and P bits clear. When the bus is busy, enabling the MSSP interrupt will generate the interrupt when the Stop condition occurs. In multi-master operation, the SDA line must be monitored for arbitration to see if the signal level is the expected output level. This check is performed in hardware with the result placed in the BCLIF bit. The states where arbitration can be lost are: * * * * * Address Transfer Data Transfer A Start Condition A Repeated Start Condition An Acknowledge Condition MULTI -MASTER COMMUNICATION, BUS COLLISION AND BUS ARBITRATION Multi-Master mode support is achieved by bus arbitration. When the master outputs address/data bits onto the SDA pin, arbitration takes place when the master outputs a `1' on SDA by letting SDA float high and another master asserts a `0'. When the SCL pin floats high, data should be stable. If the expected data on SDA is a `1' and the data sampled on the SDA pin = 0, then a bus collision has taken place. The master will set the Bus Collision Interrupt Flag, BCLIF and reset the I2C port to its Idle state (Figure 17-25). If a transmit was in progress when the bus collision occurred, the transmission is halted, the BF flag is cleared, the SDA and SCL lines are deasserted and the SSPBUF can be written to. When the user services the bus collision Interrupt Service Routine and if the I2C bus is free, the user can resume communication by asserting a Start condition. If a Start, Repeated Start, Stop or Acknowledge condition was in progress when the bus collision occurred, the condition is aborted, the SDA and SCL lines are deasserted and the respective control bits in the SSPCON2 register are cleared. When the user services the bus collision Interrupt Service Routine and if the I2C bus is free, the user can resume communication by asserting a Start condition. The master will continue to monitor the SDA and SCL pins. If a Stop condition occurs, the SSPIF bit will be set. A write to the SSPBUF will start the transmission of data at the first data bit, regardless of where the transmitter left off when the bus collision occurred. In Multi-Master mode, the interrupt generation on the detection of Start and Stop conditions allows the determination of when the bus is free. Control of the I2C bus can be taken when the P bit is set in the SSPSTAT register, or the bus is Idle and the S and P bits are cleared. FIGURE 17-25: BUS COLLISION TIMING FOR TRANSMIT AND ACKNOWLEDGE Data changes while SCL = 0 SDA line pulled low by another source SDA released by master Sample SDA. While SCL is high, data doesn't match what is driven by the master. Bus collision has occurred. SDA SCL Set bus collision interrupt (BCLIF) BCLIF (c) 2008 Microchip Technology Inc. DS39631E-page 195 PIC18F2420/2520/4420/4520 17.4.17.1 Bus Collision During a Start Condition During a Start condition, a bus collision occurs if: a) b) SDA or SCL is sampled low at the beginning of the Start condition (Figure 17-26). SCL is sampled low before SDA is asserted low (Figure 17-27). During a Start condition, both the SDA and the SCL pins are monitored. If the SDA pin is sampled low during this count, the BRG is reset and the SDA line is asserted early (Figure 17-28). If, however, a `1' is sampled on the SDA pin, the SDA pin is asserted low at the end of the BRG count. The Baud Rate Generator is then reloaded and counts down to 0; if the SCL pin is sampled as `0' during this time, a bus collision does not occur. At the end of the BRG count, the SCL pin is asserted low. Note: If the SDA pin is already low, or the SCL pin is already low, then all of the following occur: * the Start condition is aborted, * the BCLIF flag is set and * the MSSP module is reset to its Idle state (Figure 17-26). The Start condition begins with the SDA and SCL pins deasserted. When the SDA pin is sampled high, the Baud Rate Generator is loaded from SSPADD<6:0> and counts down to 0. If the SCL pin is sampled low while SDA is high, a bus collision occurs because it is assumed that another master is attempting to drive a data `1' during the Start condition. FIGURE 17-26: The reason that bus collision is not a factor during a Start condition is that no two bus masters can assert a Start condition at the exact same time. Therefore, one master will always assert SDA before the other. This condition does not cause a bus collision because the two masters must be allowed to arbitrate the first address following the Start condition. If the address is the same, arbitration must be allowed to continue into the data portion, Repeated Start or Stop conditions. BUS COLLISION DURING START CONDITION (SDA ONLY) SDA goes low before the SEN bit is set. Set BCLIF, S bit and SSPIF set because SDA = 0, SCL = 1. SDA SCL Set SEN, enable Start condition if SDA = 1, SCL = 1 SEN cleared automatically because of bus collision. MSSP module reset into Idle state. SEN BCLIF SDA sampled low before Start condition. Set BCLIF. S bit and SSPIF set because SDA = 0, SCL = 1. SSPIF and BCLIF are cleared in software S SSPIF SSPIF and BCLIF are cleared in software DS39631E-page 196 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 17-27: BUS COLLISION DURING START CONDITION (SCL = 0) SDA = 0, SCL = 1 TBRG TBRG SDA Set SEN, enable Start sequence if SDA = 1, SCL = 1 SCL SCL = 0 before SDA = 0, bus collision occurs. Set BCLIF. SEN SCL = 0 before BRG time-out, bus collision occurs. Set BCLIF. BCLIF Interrupt cleared in software S `0' `0' SSPIF `0' `0' FIGURE 17-28: BRG RESET DUE TO SDA ARBITRATION DURING START CONDITION SDA = 0, SCL = 1 Set S Less than TBRG SDA Set SSPIF TBRG SDA pulled low by other master. Reset BRG and assert SDA. SCL S SCL pulled low after BRG time-out SEN BCLIF Set SEN, enable Start sequence if SDA = 1, SCL = 1 `0' S SSPIF SDA = 0, SCL = 1, set SSPIF (c) 2008 Microchip Technology Inc. Interrupts cleared in software DS39631E-page 197 PIC18F2420/2520/4420/4520 17.4.17.2 Bus Collision During a Repeated Start Condition If SDA is low, a bus collision has occurred (i.e., another master is attempting to transmit a data `0', Figure 17-29). If SDA is sampled high, the BRG is reloaded and begins counting. If SDA goes from high-to-low before the BRG times out, no bus collision occurs because no two masters can assert SDA at exactly the same time. During a Repeated Start condition, a bus collision occurs if: a) b) A low level is sampled on SDA when SCL goes from low level to high level. SCL goes low before SDA is asserted low, indicating that another master is attempting to transmit a data `1'. If SCL goes from high-to-low before the BRG times out and SDA has not already been asserted, a bus collision occurs. In this case, another master is attempting to transmit a data `1' during the Repeated Start condition, see Figure 17-30. When the user deasserts SDA and the pin is allowed to float high, the BRG is loaded with SSPADD<6:0> and counts down to 0. The SCL pin is then deasserted and when sampled high, the SDA pin is sampled. FIGURE 17-29: If, at the end of the BRG time-out, both SCL and SDA are still high, the SDA pin is driven low and the BRG is reloaded and begins counting. At the end of the count, regardless of the status of the SCL pin, the SCL pin is driven low and the Repeated Start condition is complete. BUS COLLISION DURING A REPEATED START CONDITION (CASE 1) SDA SCL Sample SDA when SCL goes high. If SDA = 0, set BCLIF and release SDA and SCL. RSEN BCLIF Cleared in software `0' S `0' SSPIF FIGURE 17-30: BUS COLLISION DURING REPEATED START CONDITION (CASE 2) TBRG TBRG SDA SCL BCLIF SCL goes low before SDA, set BCLIF. Release SDA and SCL. Interrupt cleared in software RSEN S `0' SSPIF DS39631E-page 198 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 17.4.17.3 Bus Collision During a Stop Condition The Stop condition begins with SDA asserted low. When SDA is sampled low, the SCL pin is allowed to float. When the pin is sampled high (clock arbitration), the Baud Rate Generator is loaded with SSPADD<6:0> and counts down to 0. After the BRG times out, SDA is sampled. If SDA is sampled low, a bus collision has occurred. This is due to another master attempting to drive a data `0' (Figure 17-31). If the SCL pin is sampled low before SDA is allowed to float high, a bus collision occurs. This is another case of another master attempting to drive a data `0' (Figure 17-32). Bus collision occurs during a Stop condition if: a) b) After the SDA pin has been deasserted and allowed to float high, SDA is sampled low after the BRG has timed out. After the SCL pin is deasserted, SCL is sampled low before SDA goes high. FIGURE 17-31: BUS COLLISION DURING A STOP CONDITION (CASE 1) TBRG TBRG TBRG SDA SDA sampled low after TBRG, set BCLIF SDA asserted low SCL PEN BCLIF P `0' SSPIF `0' FIGURE 17-32: BUS COLLISION DURING A STOP CONDITION (CASE 2) TBRG TBRG TBRG SDA Assert SDA SCL SCL goes low before SDA goes high, set BCLIF PEN BCLIF P `0' SSPIF `0' (c) 2008 Microchip Technology Inc. DS39631E-page 199 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 200 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.0 ENHANCED UNIVERSAL SYNCHRONOUS ASYNCHRONOUS RECEIVER TRANSMITTER (EUSART) The Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART) module is one of the two serial I/O modules. (Generically, the USART is also known as a Serial Communications Interface or SCI.) The EUSART can be configured as a full-duplex asynchronous system that can communicate with peripheral devices, such as CRT terminals and personal computers. It can also be configured as a halfduplex, synchronous system that can communicate with peripheral devices, such as A/D or D/A integrated circuits, serial EEPROMs, etc. The Enhanced USART module implements additional features, including automatic baud rate detection and calibration, automatic wake-up on Sync Break reception and 12-bit Break character transmit. These make it ideally suited for use in Local Interconnect Network bus (LIN bus) systems. The pins of the Enhanced USART are multiplexed with PORTC. In order to configure RC6/TX/CK and RC7/RX/DT as an EUSART: * bit SPEN (RCSTA<7>) must be set (= 1) * bit TRISC<7> must be set (= 1) * bit TRISC<6> must be set (= 1) Note: The EUSART control will automatically reconfigure the pin from input to output as needed. The operation of the Enhanced USART module is controlled through three registers: * Transmit Status and Control (TXSTA) * Receive Status and Control (RCSTA) * Baud Rate Control (BAUDCON) These are detailed on the following pages in Register 18-1, Register 18-2 and Register 18-3, respectively. The EUSART can be configured in the following modes: * Asynchronous (full duplex) with: - Auto-wake-up on character reception - Auto-baud calibration - 12-bit Break character transmission * Synchronous - Master (half duplex) with selectable clock polarity * Synchronous - Slave (half duplex) with selectable clock polarity (c) 2008 Microchip Technology Inc. DS39631E-page 201 PIC18F2420/2520/4420/4520 REGISTER 18-1: TXSTA: TRANSMIT STATUS AND CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-1 R/W-0 CSRC TX9 TXEN(1) SYNC SENDB BRGH TRMT TX9D 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 CSRC: Clock Source Select bit Asynchronous mode: Don't care. Synchronous mode: 1 = Master mode (clock generated internally from BRG) 0 = Slave mode (clock from external source) bit 6 TX9: 9-Bit Transmit Enable bit 1 = Selects 9-bit transmission 0 = Selects 8-bit transmission bit 5 TXEN: Transmit Enable bit(1) 1 = Transmit enabled 0 = Transmit disabled bit 4 SYNC: EUSART Mode Select bit 1 = Synchronous mode 0 = Asynchronous mode bit 3 SENDB: Send Break Character bit Asynchronous mode: 1 = Send Sync Break on next transmission (cleared by hardware upon completion) 0 = Sync Break transmission completed Synchronous mode: Don't care. bit 2 BRGH: High Baud Rate Select bit Asynchronous mode: 1 = High speed 0 = Low speed Synchronous mode: Unused in this mode. bit 1 TRMT: Transmit Shift Register Status bit 1 = TSR empty 0 = TSR full bit 0 TX9D: 9th Bit of Transmit Data Can be address/data bit or a parity bit. Note 1: SREN/CREN overrides TXEN in Sync mode. DS39631E-page 202 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 18-2: RCSTA: RECEIVE STATUS AND CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R-0 R-0 R-x SPEN RX9 SREN CREN ADDEN FERR OERR RX9D bit 7 bit 0 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 SPEN: Serial Port Enable bit 1 = Serial port enabled (configures RX/DT and TX/CK pins as serial port pins) 0 = Serial port disabled (held in Reset) bit 6 RX9: 9-Bit Receive Enable bit 1 = Selects 9-bit reception 0 = Selects 8-bit reception bit 5 SREN: Single Receive Enable bit Asynchronous mode: Don't care. Synchronous mode - Master: 1 = Enables single receive 0 = Disables single receive This bit is cleared after reception is complete. Synchronous mode - Slave: Don't care. bit 4 CREN: Continuous Receive Enable bit Asynchronous mode: 1 = Enables receiver 0 = Disables receiver Synchronous mode: 1 = Enables continuous receive until enable bit, CREN, is cleared (CREN overrides SREN) 0 = Disables continuous receive bit 3 ADDEN: Address Detect Enable bit Asynchronous mode 9-Bit (RX9 = 1): 1 = Enables address detection, enables interrupt and loads the receive buffer when RSR<8> is set 0 = Disables address detection, all bytes are received and ninth bit can be used as parity bit Asynchronous mode 9-Bit (RX9 = 0): Don't care. bit 2 FERR: Framing Error bit 1 = Framing error (can be cleared by reading RCREG register and receiving next valid byte) 0 = No framing error bit 1 OERR: Overrun Error bit 1 = Overrun error (can be cleared by clearing bit, CREN) 0 = No overrun error bit 0 RX9D: 9th Bit of Received Data This can be address/data bit or a parity bit and must be calculated by user firmware. (c) 2008 Microchip Technology Inc. DS39631E-page 203 PIC18F2420/2520/4420/4520 REGISTER 18-3: BAUDCON: BAUD RATE CONTROL REGISTER R/W-0 R-1 R/W-0 R/W-0 R/W-0 U-0 R/W-0 R/W-0 ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 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 ABDOVF: Auto-Baud Acquisition Rollover Status bit 1 = A BRG rollover has occurred during Auto-Baud Rate Detect mode (must be cleared in software) 0 = No BRG rollover has occurred bit 6 RCIDL: Receive Operation Idle Status bit 1 = Receive operation is Idle 0 = Receive operation is active bit 5 RXDTP: Data/Receive Polarity Select bit Asynchronous mode: 1 = Receive data (RX) is inverted (active-low) 0 = Receive data (RX) is not inverted (active-high) Synchronous mode: 1 = Data (DT) is inverted (active-low) 0 = Data (DT) is not inverted (active-high) bit 4 TXCKP: Clock and Data Polarity Select bit Asynchronous mode: 1 = Idle state for transmit (TX) is a low level 0 = Idle state for transmit (TX) is a high level Synchronous mode: 1 = Idle state for clock (CK) is a high level 0 = Idle state for clock (CK) is a low level bit 3 BRG16: 16-Bit Baud Rate Register Enable bit 1 = 16-bit Baud Rate Generator - SPBRGH and SPBRG 0 = 8-bit Baud Rate Generator - SPBRG only (Compatible mode), SPBRGH value ignored bit 2 Unimplemented: Read as `0' bit 1 WUE: Wake-up Enable bit Asynchronous mode: 1 = EUSART will continue to sample the RX pin - interrupt generated on falling edge; bit cleared in hardware on following rising edge 0 = RX pin not monitored or rising edge detected Synchronous mode: Unused in this mode. bit 0 ABDEN: Auto-Baud Detect Enable bit Asynchronous mode: 1 = Enable baud rate measurement on the next character. Requires reception of a Sync field (55h); cleared in hardware upon completion. 0 = Baud rate measurement disabled or completed Synchronous mode: Unused in this mode. DS39631E-page 204 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.1 Baud Rate Generator (BRG) The BRG is a dedicated, 8-bit or 16-bit generator that supports both the Asynchronous and Synchronous modes of the EUSART. By default, the BRG operates in 8-bit mode; setting the BRG16 bit (BAUDCON<3>) selects 16-bit mode. The SPBRGH:SPBRG register pair controls the period of a free-running timer. In Asynchronous mode, bits, BRGH (TXSTA<2>) and BRG16 (BAUDCON<3>), also control the baud rate. In Synchronous mode, BRGH is ignored. Table 18-1 shows the formula for computation of the baud rate for different EUSART modes which only apply in Master mode (internally generated clock). Given the desired baud rate and FOSC, the nearest integer value for the SPBRGH:SPBRG registers can be calculated using the formulas in Table 18-1. From this, the error in baud rate can be determined. An example calculation is shown in Example 18-1. Typical baud rates and error values for the various Asynchronous modes are shown in Table 18-2. It may be TABLE 18-1: advantageous to use the high baud rate (BRGH = 1) or the 16-bit BRG to reduce the baud rate error, or achieve a slow baud rate for a fast oscillator frequency. Writing a new value to the SPBRGH:SPBRG registers causes the BRG timer to be reset (or cleared). This ensures the BRG does not wait for a timer overflow before outputting the new baud rate. 18.1.1 OPERATION IN POWER-MANAGED MODES The device clock is used to generate the desired baud rate. When one of the power-managed modes is entered, the new clock source may be operating at a different frequency. This may require an adjustment to the value in the SPBRG register pair. 18.1.2 SAMPLING The data on the RX pin is sampled three times by a majority detect circuit to determine if a high or a low level is present at the RX pin. BAUD RATE FORMULAS Configuration Bits BRG/EUSART Mode Baud Rate Formula 8-Bit/Asynchronous FOSC/[64 (n + 1)] SYNC BRG16 BRGH 0 0 0 0 0 1 8-Bit/Asynchronous 0 1 0 16-Bit/Asynchronous 0 1 1 16-Bit/Asynchronous 1 0 x 8-Bit/Synchronous 1 1 x 16-Bit/Synchronous FOSC/[16 (n + 1)] FOSC/[4 (n + 1)] Legend: x = Don't care, n = value of SPBRGH:SPBRG register pair (c) 2008 Microchip Technology Inc. DS39631E-page 205 PIC18F2420/2520/4420/4520 EXAMPLE 18-1: CALCULATING BAUD RATE ERROR For a device with FOSC of 16 MHz, desired baud rate of 9600, Asynchronous mode, 8-bit BRG: Desired Baud Rate = FOSC/(64 ([SPBRGH:SPBRG] + 1)) Solving for SPBRGH:SPBRG: X = ((FOSC/Desired Baud Rate)/64) - 1 = ((16000000/9600)/64) - 1 = [25.042] = 25 Calculated Baud Rate = 16000000/(64 (25 + 1)) = 9615 Error = (Calculated Baud Rate - Desired Baud Rate)/Desired Baud Rate = (9615 - 9600)/9600 = 0.16% TABLE 18-2: REGISTERS ASSOCIATED WITH BAUD RATE GENERATOR Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page TXSTA CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 RCSTA SPEN Name BAUDCON ABDOVF RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the BRG. DS39631E-page 206 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES SYNC = 0, BRGH = 0, BRG16 = 0 BAUD RATE (K) FOSC = 40.000 MHz FOSC = 20.000 MHz SPBRG Value Actual Rate (K) SPBRG Value FOSC = 10.000 MHz Actual Rate (K) SPBRG Value FOSC = 8.000 MHz Actual Rate (K) SPBRG Value Actual Rate (K) % Error 0.3 -- -- -- -- -- -- -- -- -- -- -- -- 1.2 -- -- -- 1.221 1.73 255 1.202 0.16 129 1.201 -0.16 103 2.4 2.441 1.73 255 2.404 0.16 129 2.404 0.16 64 2.403 -0.16 51 9.6 9.615 0.16 64 9.766 1.73 31 9.766 1.73 15 9.615 -0.16 12 19.2 19.531 1.73 31 19.531 1.73 15 19.531 1.73 7 -- -- -- 57.6 56.818 -1.36 10 62.500 8.51 4 52.083 -9.58 2 -- -- -- 115.2 125.000 8.51 4 104.167 -9.58 2 78.125 -32.18 1 -- -- -- (decimal) % Error (decimal) % Error (decimal) % Error (decimal) SYNC = 0, BRGH = 0, BRG16 = 0 BAUD RATE (K) FOSC = 4.000 MHz FOSC = 2.000 MHz (decimal) 0.16 207 0.300 -0.16 103 0.300 -0.16 51 0.16 51 1.201 -0.16 25 1.201 -0.16 12 2.404 0.16 25 2.403 -0.16 12 -- -- -- 9.6 8.929 -6.99 6 -- -- -- -- -- -- 19.2 20.833 8.51 2 -- -- -- -- -- -- % Error 0.3 0.300 1.2 1.202 2.4 SPBRG Value % Error SPBRG Value FOSC = 1.000 MHz Actual Rate (K) Actual Rate (K) (decimal) Actual Rate (K) % Error SPBRG Value (decimal) 57.6 62.500 8.51 0 -- -- -- -- -- -- 115.2 62.500 -45.75 0 -- -- -- -- -- -- SYNC = 0, BRGH = 1, BRG16 = 0 BAUD RATE (K) FOSC = 40.000 MHz FOSC = 20.000 MHz (decimal) Actual Rate (K) % Error -- -- -- -- -- -- -- -- -- 9.766 1.73 255 Actual Rate (K) % Error 0.3 -- 1.2 -- 2.4 9.6 SPBRG Value SPBRG Value FOSC = 10.000 MHz (decimal) Actual Rate (K) % Error -- -- -- -- -- -- -- -- -- 9.615 0.16 SPBRG Value FOSC = 8.000 MHz (decimal) Actual Rate (K) % Error SPBRG Value -- -- -- -- -- -- -- -- -- 2.441 1.73 255 2.403 -0.16 207 129 9.615 0.16 64 9.615 -0.16 51 25 (decimal) -- 19.2 19.231 0.16 129 19.231 0.16 64 19.531 1.73 31 19.230 -0.16 57.6 58.140 0.94 42 56.818 -1.36 21 56.818 -1.36 10 55.555 3.55 8 115.2 113.636 -1.36 21 113.636 -1.36 10 125.000 8.51 4 -- -- -- SYNC = 0, BRGH = 1, BRG16 = 0 BAUD RATE (K) FOSC = 4.000 MHz Actual Rate (K) % Error FOSC = 2.000 MHz SPBRG Value (decimal) Actual Rate (K) % Error SPBRG Value (decimal) FOSC = 1.000 MHz Actual Rate (K) % Error SPBRG Value (decimal) 0.3 -- -- -- -- -- -- 0.300 -0.16 207 1.2 1.202 0.16 207 1.201 -0.16 103 1.201 -0.16 51 2.4 2.404 0.16 103 2.403 -0.16 51 2.403 -0.16 25 9.6 9.615 0.16 25 9.615 -0.16 12 -- -- -- 19.2 19.231 0.16 12 -- -- -- -- -- -- 57.6 62.500 8.51 3 -- -- -- -- -- -- 115.2 125.000 8.51 1 -- -- -- -- -- -- (c) 2008 Microchip Technology Inc. DS39631E-page 207 PIC18F2420/2520/4420/4520 TABLE 18-3: BAUD RATES FOR ASYNCHRONOUS MODES (CONTINUED) SYNC = 0, BRGH = 0, BRG16 = 1 BAUD RATE (K) FOSC = 40.000 MHz Actual Rate (K) % Error FOSC = 20.000 MHz SPBRG Value (decimal) Actual Rate (K) % Error FOSC = 10.000 MHz (decimal) Actual Rate (K) SPBRG Value % Error FOSC = 8.000 MHz (decimal) Actual Rate (K) % Error SPBRG Value SPBRG Value (decimal) 0.3 0.300 0.00 8332 0.300 0.02 4165 0.300 0.02 2082 0.300 -0.04 1.2 1.200 0.02 2082 1.200 -0.03 1041 1.200 -0.03 520 1.201 -0.16 1665 415 2.4 2.402 0.06 1040 2.399 -0.03 520 2.404 0.16 259 2.403 -0.16 207 9.6 9.615 0.16 259 9.615 0.16 129 9.615 0.16 64 9.615 -0.16 51 25 19.2 19.231 0.16 129 19.231 0.16 64 19.531 1.73 31 19.230 -0.16 57.6 58.140 0.94 42 56.818 -1.36 21 56.818 -1.36 10 55.555 3.55 8 115.2 113.636 -1.36 21 113.636 -1.36 10 125.000 8.51 4 -- -- -- SYNC = 0, BRGH = 0, BRG16 = 1 BAUD RATE (K) FOSC = 4.000 MHz FOSC = 2.000 MHz (decimal) Actual Rate (K) % Error 0.04 832 0.300 0.16 207 1.201 2.404 0.16 103 9.6 9.615 0.16 19.2 19.231 57.6 62.500 115.2 125.000 FOSC = 1.000 MHz (decimal) Actual Rate (K) % Error -0.16 415 0.300 -0.16 -0.16 103 1.201 -0.16 51 2.403 -0.16 51 2.403 -0.16 25 25 9.615 -0.16 12 -- -- -- 0.16 12 -- -- -- -- -- -- 8.51 3 -- -- -- -- -- -- 8.51 1 -- -- -- -- -- -- Actual Rate (K) % Error 0.3 0.300 1.2 1.202 2.4 SPBRG Value SPBRG Value SPBRG Value (decimal) 207 SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1 BAUD RATE (K) FOSC = 40.000 MHz FOSC = 20.000 MHz (decimal) Actual Rate (K) % Error 0.00 33332 0.300 0.00 8332 1.200 0.02 4165 Actual Rate (K) % Error 0.3 0.300 1.2 1.200 2.4 2.400 SPBRG Value FOSC = 10.000 MHz (decimal) Actual Rate (K) % Error 0.00 16665 0.300 0.02 4165 1.200 2.400 0.02 2082 2.402 SPBRG Value FOSC = 8.000 MHz (decimal) Actual Rate (K) % Error 0.00 8332 0.300 -0.01 6665 0.02 2082 1.200 -0.04 1665 0.06 1040 2.400 -0.04 832 SPBRG Value SPBRG Value (decimal) 9.6 9.606 0.06 1040 9.596 -0.03 520 9.615 0.16 259 9.615 -0.16 207 19.2 19.193 -0.03 520 19.231 0.16 259 19.231 0.16 129 19.230 -0.16 103 57.6 57.803 0.35 172 57.471 -0.22 86 58.140 0.94 42 57.142 0.79 34 115.2 114.943 -0.22 86 116.279 0.94 42 113.636 -1.36 21 117.647 -2.12 16 SYNC = 0, BRGH = 1, BRG16 = 1 or SYNC = 1, BRG16 = 1 BAUD RATE (K) 0.3 1.2 FOSC = 4.000 MHz Actual Rate (K) % Error 0.300 1.200 0.01 0.04 FOSC = 2.000 MHz (decimal) Actual Rate (K) % Error 3332 832 0.300 1.201 -0.04 -0.16 SPBRG Value FOSC = 1.000 MHz (decimal) Actual Rate (K) % Error 1665 415 0.300 1.201 -0.04 -0.16 832 207 103 SPBRG Value SPBRG Value (decimal) 2.4 2.404 0.16 415 2.403 -0.16 207 2.403 -0.16 9.6 9.615 0.16 103 9.615 -0.16 51 9.615 -0.16 25 19.2 19.231 0.16 51 19.230 -0.16 25 19.230 -0.16 12 57.6 58.824 2.12 16 55.555 3.55 8 -- -- -- 115.2 111.111 -3.55 8 -- -- -- -- -- -- DS39631E-page 208 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.1.3 AUTO-BAUD RATE DETECT The Enhanced USART module supports the automatic detection and calibration of baud rate. This feature is active only in Asynchronous mode and while the WUE bit is clear. Note 1: If the WUE bit is set with the ABDEN bit, Auto-Baud Rate Detection will occur on the byte following the Break character. 2: It is up to the user to determine that the incoming character baud rate is within the range of the selected BRG clock source. Some combinations of oscillator frequency and EUSART baud rates are not possible due to bit error rates. Overall system timing and communication baud rates must be taken into consideration when using the Auto-Baud Rate Detection feature. The automatic baud rate measurement sequence (Figure 18-1) begins whenever a Start bit is received and the ABDEN bit is set. The calculation is self-averaging. In the Auto-Baud Rate Detect (ABD) mode, the clock to the BRG is reversed. Rather than the BRG clocking the incoming RX signal, the RX signal is timing the BRG. In ABD mode, the internal Baud Rate Generator is used as a counter to time the bit period of the incoming serial byte stream. Once the ABDEN bit is set, the state machine will clear the BRG and look for a Start bit. The Auto-Baud Rate Detect must receive a byte with the value 55h (ASCII "U", which is also the LIN bus Sync character) in order to calculate the proper bit rate. The measurement is taken over both a low and a high bit time in order to minimize any effects caused by asymmetry of the incoming signal. After a Start bit, the SPBRG begins counting up, using the preselected clock source on the first rising edge of RX. After eight bits on the RX pin or the fifth rising edge, an accumulated value totalling the proper BRG period is left in the SPBRGH:SPBRG register pair. Once the 5th edge is seen (this should correspond to the Stop bit), the ABDEN bit is automatically cleared. If a rollover of the BRG occurs (an overflow from FFFFh to 0000h), the event is trapped by the ABDOVF status bit (BAUDCON<7>). It is set in hardware by BRG rollovers and can be set or cleared by the user in software. ABD mode remains active after rollover events and the ABDEN bit remains set (Figure 18-2). TABLE 18-4: BRG COUNTER CLOCK RATES BRG16 BRGH BRG Counter Clock 0 0 FOSC/512 0 1 FOSC/128 1 0 FOSC/128 1 1 FOSC/32 Note: During the ABD sequence, SPBRG and SPBRGH are both used as a 16-bit counter, independent of BRG16 setting. 18.1.3.1 ABD and EUSART Transmission Since the BRG clock is reversed during ABD acquisition, the EUSART transmitter cannot be used during ABD. This means that whenever the ABDEN bit is set, TXREG cannot be written to. Users should also ensure that ABDEN does not become set during a transmit sequence. Failing to do this may result in unpredictable EUSART operation. While calibrating the baud rate period, the BRG registers are clocked at 1/8th the preconfigured clock rate. Note that the BRG clock will be configured by the BRG16 and BRGH bits. Independent of the BRG16 bit setting, both the SPBRG and SPBRGH will be used as a 16-bit counter. This allows the user to verify that no carry occurred for 8-bit modes by checking for 00h in the SPBRGH register. Refer to Table 18-4 for counter clock rates to the BRG. While the ABD sequence takes place, the EUSART state machine is held in Idle. The RCIF interrupt is set once the fifth rising edge on RX is detected. The value in the RCREG needs to be read to clear the RCIF interrupt. The contents of RCREG should be discarded. (c) 2008 Microchip Technology Inc. DS39631E-page 209 PIC18F2420/2520/4420/4520 FIGURE 18-1: BRG Value AUTOMATIC BAUD RATE CALCULATION XXXXh RX pin 0000h 001Ch Start Edge #1 Bit 1 Bit 0 Edge #2 Bit 3 Bit 2 Edge #3 Bit 5 Bit 4 Edge #4 Bit 7 Bit 6 Edge #5 Stop Bit BRG Clock Auto-Cleared Set by User ABDEN bit RCIF bit (Interrupt) Read RCREG SPBRG XXXXh 1Ch SPBRGH XXXXh 00h Note: The ABD sequence requires the EUSART module to be configured in Asynchronous mode and WUE = 0. FIGURE 18-2: BRG OVERFLOW SEQUENCE BRG Clock ABDEN bit RX pin Start Bit 0 ABDOVF bit FFFFh BRG Value DS39631E-page 210 XXXXh 0000h 0000h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.2 Once the TXREG register transfers the data to the TSR register (occurs in one TCY), the TXREG register is empty and the TXIF flag bit (PIR1<4>) is set. This interrupt can be enabled or disabled by setting or clearing the interrupt enable bit, TXIE (PIE1<4>). TXIF will be set regardless of the state of TXIE; it cannot be cleared in software. TXIF is also not cleared immediately upon loading TXREG, but becomes valid in the second instruction cycle following the load instruction. Polling TXIF immediately following a load of TXREG will return invalid results. EUSART Asynchronous Mode The Asynchronous mode of operation is selected by clearing the SYNC bit (TXSTA<4>). In this mode, the EUSART uses standard Non-Return-to-Zero (NRZ) format (one Start bit, eight or nine data bits and one Stop bit). The most common data format is 8 bits. An on-chip, dedicated 8-bit/16-bit Baud Rate Generator can be used to derive standard baud rate frequencies from the oscillator. The EUSART transmits and receives the LSb first. The EUSART's transmitter and receiver are functionally independent but use the same data format and baud rate. The Baud Rate Generator produces a clock, either x16 or x64 of the bit shift rate depending on the BRGH and BRG16 bits (TXSTA<2> and BAUDCON<3>). Parity is not supported by the hardware but can be implemented in software and stored as the 9th data bit. While TXIF indicates the status of the TXREG register, another bit, TRMT (TXSTA<1>), shows the status of the TSR register. TRMT is a read-only bit which is set when the TSR register is empty. No interrupt logic is tied to this bit so the user has to poll this bit in order to determine if the TSR register is empty. Note 1: The TSR register is not mapped in data memory so it is not available to the user. When operating in Asynchronous mode, the EUSART module consists of the following important elements: * * * * * * * 2: Flag bit, TXIF, is set when enable bit, TXEN, is set. Baud Rate Generator Sampling Circuit Asynchronous Transmitter Asynchronous Receiver Auto-Wake-up on Sync Break Character 12-Bit Break Character Transmit Auto-Baud Rate Detection 18.2.1 To set up an Asynchronous Transmission: 1. 2. EUSART ASYNCHRONOUS TRANSMITTER 3. 4. The EUSART transmitter block diagram is shown in Figure 18-3. The heart of the transmitter is the Transmit (Serial) Shift Register (TSR). The Shift register obtains its data from the Read/Write Transmit Buffer register, TXREG. The TXREG register is loaded with data in software. The TSR register is not loaded until the Stop bit has been transmitted from the previous load. As soon as the Stop bit is transmitted, the TSR is loaded with new data from the TXREG register (if available). FIGURE 18-3: 5. 6. 7. 8. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. Enable the asynchronous serial port by clearing bit, SYNC, and setting bit, SPEN. If interrupts are desired, set enable bit, TXIE. If 9-bit transmission is desired, set transmit bit, TX9. Can be used as address/data bit. Enable the transmission by setting bit, TXEN, which will also set bit, TXIF. If 9-bit transmission is selected, the ninth bit should be loaded in bit, TX9D. Load data to the TXREG register (starts transmission). If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. EUSART TRANSMIT BLOCK DIAGRAM Data Bus TXIF TXREG Register TXIE 8 MSb (8) LSb * * * Pin Buffer and Control 0 TSR Register TX pin Interrupt TXEN Baud Rate CLK TRMT BRG16 SPBRGH SPBRG Baud Rate Generator (c) 2008 Microchip Technology Inc. SPEN TX9 TX9D DS39631E-page 211 PIC18F2420/2520/4420/4520 FIGURE 18-4: ASYNCHRONOUS TRANSMISSION Write to TXREG Word 1 BRG Output (Shift Clock) TX (pin) Start bit bit 0 bit 1 bit 7/8 Stop bit Word 1 TXIF bit (Transmit Buffer Reg. Empty Flag) 1 TCY Word 1 Transmit Shift Reg TRMT bit (Transmit Shift Reg. Empty Flag) FIGURE 18-5: ASYNCHRONOUS TRANSMISSION (BACK TO BACK) Write to TXREG Word 2 Word 1 BRG Output (Shift Clock) TX (pin) Start bit bit 0 bit 1 1 TCY TXIF bit (Interrupt Reg. Flag) bit 7/8 Stop bit Start bit bit 0 Word 2 Word 1 1 TCY Word 1 Transmit Shift Reg. TRMT bit (Transmit Shift Reg. Empty Flag) Word 2 Transmit Shift Reg. Note: This timing diagram shows two consecutive transmissions. TABLE 18-5: Name REGISTERS ASSOCIATED WITH ASYNCHRONOUS TRANSMISSION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCSTA TXREG EUSART Transmit Register 51 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 BAUDCON ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 TXSTA Legend: -- = unimplemented locations read as `0'. Shaded cells are not used for asynchronous transmission. Note 1: Reserved in 28-pin devices; always maintain these bits clear. DS39631E-page 212 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.2.2 EUSART ASYNCHRONOUS RECEIVER 18.2.3 The receiver block diagram is shown in Figure 18-6. The data is received on the RX pin and drives the data recovery block. The data recovery block is actually a high-speed shifter operating at x16 times the baud rate, whereas the main receive serial shifter operates at the bit rate or at FOSC. This mode would typically be used in RS-232 systems. This mode would typically be used in RS-485 systems. To set up an Asynchronous Reception with Address Detect Enable: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. 2. Enable the asynchronous serial port by clearing the SYNC bit and setting the SPEN bit. 3. If interrupts are required, set the RCEN bit and select the desired priority level with the RCIP bit. 4. Set the RX9 bit to enable 9-bit reception. 5. Set the ADDEN bit to enable address detect. 6. Enable reception by setting the CREN bit. 7. The RCIF bit will be set when reception is complete. The interrupt will be Acknowledged if the RCIE and GIE bits are set. 8. Read the RCSTA register to determine if any error occurred during reception, as well as read bit 9 of data (if applicable). 9. Read RCREG to determine if the device is being addressed. 10. If any error occurred, clear the CREN bit. 11. If the device has been addressed, clear the ADDEN bit to allow all received data into the receive buffer and interrupt the CPU. To set up an Asynchronous Reception: 1. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRGH and BRG16 bits, as required, to achieve the desired baud rate. 2. Enable the asynchronous serial port by clearing bit, SYNC, and setting bit, SPEN. 3. If interrupts are desired, set enable bit, RCIE. 4. If 9-bit reception is desired, set bit, RX9. 5. Enable the reception by setting bit, CREN. 6. Flag bit, RCIF, will be set when reception is complete and an interrupt will be generated if enable bit, RCIE, was set. 7. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. 8. Read the 8-bit received data by reading the RCREG register. 9. If any error occurred, clear the error by clearing enable bit, CREN. 10. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. FIGURE 18-6: SETTING UP 9-BIT MODE WITH ADDRESS DETECT EUSART RECEIVE BLOCK DIAGRAM CREN OERR FERR x64 Baud Rate CLK BRG16 SPBRGH SPBRG Baud Rate Generator / 64 or / 16 or /4 RSR Register MSb Stop (8) 7 * * * 1 LSb 0 Start RX9 Pin Buffer and Control Data Recovery RX RX9D RCREG Register FIFO SPEN 8 Interrupt RCIF Data Bus RCIE (c) 2008 Microchip Technology Inc. DS39631E-page 213 PIC18F2420/2520/4420/4520 FIGURE 18-7: ASYNCHRONOUS RECEPTION Start bit RX (pin) bit 0 bit 7/8 Stop bit bit 1 Rcv Shift Reg Rcv Buffer Reg Start bit bit 0 bit 7/8 Start bit bit 7/8 Stop bit Word 2 RCREG Word 1 RCREG Read Rcv Buffer Reg RCREG Stop bit RCIF (Interrupt Flag) OERR bit CREN Note: This timing diagram shows three words appearing on the RX input. causing the OERR (overrun) bit to be set. TABLE 18-6: Name The RCREG (receive buffer) is read after the third word REGISTERS ASSOCIATED WITH ASYNCHRONOUS RECEPTION Bit 7 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 Bit 6 INTCON GIE/GIEH PEIE/GIEL PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCSTA RCREG EUSART Receive Register 51 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D BAUDCON ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 TXSTA 51 51 Legend: -- = unimplemented locations read as `0'. Shaded cells are not used for asynchronous reception. Note 1: Reserved in 28-pin devices; always maintain these bits clear. 18.2.4 AUTO-WAKE-UP ON SYNC BREAK CHARACTER During Sleep mode, all clocks to the EUSART are suspended. Because of this, the Baud Rate Generator is inactive and a proper byte reception cannot be performed. The auto-wake-up feature allows the controller to wake-up due to activity on the RX/DT line while the EUSART is operating in Asynchronous mode. The auto-wake-up feature is enabled by setting the WUE bit (BAUDCON<1>). Once set, the typical receive sequence on RX/DT is disabled and the EUSART remains in an Idle state, monitoring for a wake-up event independent of the CPU mode. A wake-up event consists of a high-to-low transition on the RX/DT line. (This coincides with the start of a Sync Break or a Wake-up Signal character for the LIN protocol.) DS39631E-page 214 Following a wake-up event, the module generates an RCIF interrupt. The interrupt is generated synchronously to the Q clocks in normal operating modes (Figure 18-8) and asynchronously, if the device is in Sleep mode (Figure 18-9). The interrupt condition is cleared by reading the RCREG register. The WUE bit is automatically cleared once a low-tohigh transition is observed on the RX line following the wake-up event. At this point, the EUSART module is in Idle mode and returns to normal operation. This signals to the user that the Sync Break event is over. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.2.4.1 Special Considerations Using Auto-Wake-up 18.2.4.2 Since auto-wake-up functions by sensing rising edge transitions on RX/DT, information with any state changes before the Stop bit may signal a false End-ofCharacter (EOC) and cause data or framing errors. To work properly, therefore, the initial character in the transmission must be all `0's. This can be 00h (8 bytes) for standard RS-232 devices or 000h (12 bits) for LIN bus. The timing of WUE and RCIF events may cause some confusion when it comes to determining the validity of received data. As noted, setting the WUE bit places the EUSART in an Idle mode. The wake-up event causes a receive interrupt by setting the RCIF bit. The WUE bit is cleared after this when a rising edge is seen on RX/DT. The interrupt condition is then cleared by reading the RCREG register. Ordinarily, the data in RCREG will be dummy data and should be discarded. Oscillator start-up time must also be considered, especially in applications using oscillators with longer start-up intervals (i.e., XT or HS mode). The Sync Break (or Wake-up Signal) character must be of sufficient length and be followed by a sufficient interval to allow enough time for the selected oscillator to start and provide proper initialization of the EUSART. FIGURE 18-8: Special Considerations Using the WUE Bit The fact that the WUE bit has been cleared (or is still set) and the RCIF flag is set should not be used as an indicator of the integrity of the data in RCREG. Users should consider implementing a parallel method in firmware to verify received data integrity. To assure that no actual data is lost, check the RCIDL bit to verify that a receive operation is not in process. If a receive operation is not occurring, the WUE bit may then be set just prior to entering the Sleep mode. AUTO-WAKE-UP BIT (WUE) TIMINGS DURING NORMAL OPERATION Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 OSC1 Bit Set by User Auto-Cleared WUE bit(1) RX/DT Line RCIF Cleared Due to User Read of RCREG Note 1: The EUSART remains in Idle while the WUE bit is set. FIGURE 18-9: AUTO-WAKE-UP BIT (WUE) TIMINGS DURING SLEEP Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 OSC1 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Bit Set by User Auto-Cleared WUE bit(2) RX/DT Line Note 1 RCIF Sleep Command Executed Note 1: 2: Sleep Ends Cleared Due to User Read of RCREG If the wake-up event requires long oscillator warm-up time, the auto-clear of the WUE bit can occur before the oscillator is ready. This sequence should not depend on the presence of Q clocks. The EUSART remains in Idle while the WUE bit is set. (c) 2008 Microchip Technology Inc. DS39631E-page 215 PIC18F2420/2520/4420/4520 18.2.5 BREAK CHARACTER SEQUENCE The EUSART module has the capability of sending the special Break character sequences that are required by the LIN bus standard. The Break character transmit consists of a Start bit, followed by twelve `0' bits and a Stop bit. The frame Break character is sent whenever the SENDB and TXEN bits (TXSTA<3> and TXSTA<5>) are set while the Transmit Shift register is loaded with data. Note that the value of data written to TXREG will be ignored and all `0's will be transmitted. The SENDB bit is automatically reset by hardware after the corresponding Stop bit is sent. This allows the user to preload the transmit FIFO with the next transmit byte following the Break character (typically, the Sync character in the LIN specification). Note that the data value written to the TXREG for the Break character is ignored. The write simply serves the purpose of initiating the proper sequence. The TRMT bit indicates when the transmit operation is active or Idle, just as it does during normal transmission. See Figure 18-10 for the timing of the Break character sequence. 18.2.5.1 Break and Sync Transmit Sequence The following sequence will send a message frame header made up of a Break, followed by an Auto-Baud Sync byte. This sequence is typical of a LIN bus master. FIGURE 18-10: Write to TXREG 1. 2. 3. 4. 5. Configure the EUSART for the desired mode. Set the TXEN and SENDB bits to set up the Break character. Load the TXREG with a dummy character to initiate transmission (the value is ignored). Write `55h' to TXREG to load the Sync character into the transmit FIFO buffer. After the Break has been sent, the SENDB bit is reset by hardware. The Sync character now transmits in the preconfigured mode. When the TXREG becomes empty, as indicated by the TXIF, the next data byte can be written to TXREG. 18.2.6 RECEIVING A BREAK CHARACTER The Enhanced USART module can receive a Break character in two ways. The first method forces configuration of the baud rate at a frequency of 9/13 the typical speed. This allows for the Stop bit transition to be at the correct sampling location (13 bits for Break versus Start bit and 8 data bits for typical data). The second method uses the auto-wake-up feature described in Section 18.2.4 "Auto-Wake-up on Sync Break Character". By enabling this feature, the EUSART will sample the next two transitions on RX/DT, cause an RCIF interrupt and receive the next data byte followed by another interrupt. Note that following a Break character, the user will typically want to enable the Auto-Baud Rate Detect feature. For both methods, the user can set the ABD bit once the TXIF interrupt is observed. SEND BREAK CHARACTER SEQUENCE Dummy Write BRG Output (Shift Clock) TX (pin) Start Bit Bit 0 Bit 1 Bit 11 Stop Bit Break TXIF bit (Transmit Buffer Reg. Empty Flag) TRMT bit (Transmit Shift Reg. Empty Flag) SENDB Sampled Here Auto-Cleared SENDB (Transmit Shift Reg. Empty Flag) DS39631E-page 216 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.3 Once the TXREG register transfers the data to the TSR register (occurs in one TCY), the TXREG is empty and the TXIF flag bit (PIR1<4>) is set. The interrupt can be enabled or disabled by setting or clearing the interrupt enable bit, TXIE (PIE1<4>). TXIF is set regardless of the state of enable bit, TXIE; it cannot be cleared in software. It will reset only when new data is loaded into the TXREG register. EUSART Synchronous Master Mode The Synchronous Master mode is entered by setting the CSRC bit (TXSTA<7>). In this mode, the data is transmitted in a half-duplex manner (i.e., transmission and reception do not occur at the same time). When transmitting data, the reception is inhibited and vice versa. Synchronous mode is entered by setting bit, SYNC (TXSTA<4>). In addition, enable bit, SPEN (RCSTA<7>), is set in order to configure the TX and RX pins to CK (clock) and DT (data) lines, respectively. While flag bit, TXIF, indicates the status of the TXREG register, another bit, TRMT (TXSTA<1>), shows the status of the TSR register. TRMT is a read-only bit which is set when the TSR is empty. No interrupt logic is tied to this bit so the user has to poll this bit in order to determine if the TSR register is empty. The TSR is not mapped in data memory so it is not available to the user. The Master mode indicates that the processor transmits the master clock on the CK line. Clock polarity is selected with the TXCKP bit (BAUDCON<4>); setting TXCKP sets the Idle state on CK as high, while clearing the bit sets the Idle state as low. This option is provided to support Microwire devices with this module. 18.3.1 To set up a Synchronous Master Transmission: 1. EUSART SYNCHRONOUS MASTER TRANSMISSION 2. The EUSART transmitter block diagram is shown in Figure 18-3. The heart of the transmitter is the Transmit (Serial) Shift Register (TSR). The Shift register obtains its data from the Read/Write Transmit Buffer register, TXREG. The TXREG register is loaded with data in software. The TSR register is not loaded until the last bit has been transmitted from the previous load. As soon as the last bit is transmitted, the TSR is loaded with new data from the TXREG (if available). FIGURE 18-11: 3. 4. 5. 6. 7. 8. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRG16 bit, as required, to achieve the desired baud rate. Enable the synchronous master serial port by setting bits, SYNC, SPEN and CSRC. If interrupts are desired, set enable bit, TXIE. If 9-bit transmission is desired, set bit, TX9. Enable the transmission by setting bit, TXEN. If 9-bit transmission is selected, the ninth bit should be loaded in bit, TX9D. Start transmission by loading data to the TXREG register. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. SYNCHRONOUS TRANSMISSION Q1 Q2 Q3Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 RC7/RX/DT bit 0 bit 1 bit 2 Q3 Q4 Q1 Q2 Q3 Q4 Q1Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 bit 7 Word 1 bit 0 bit 1 bit 7 Word 2 RC6/TX/CK pin (TXCKP = 0) RC6/TX/CK pin (TXCKP = 1) Write to TXREG Reg Write Word 1 Write Word 2 TXIF bit (Interrupt Flag) TRMT bit TXEN bit Note: `1' `1' Sync Master mode, SPBRG = 0, continuous transmission of two 8-bit words. (c) 2008 Microchip Technology Inc. DS39631E-page 217 PIC18F2420/2520/4420/4520 FIGURE 18-12: SYNCHRONOUS TRANSMISSION (THROUGH TXEN) RC7/RX/DT pin bit 0 bit 1 bit 2 bit 6 bit 7 RC6/TX/CK pin Write to TXREG reg TXIF bit TRMT bit TXEN bit TABLE 18-7: Name REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER TRANSMISSION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCSTA TXREG EUSART Transmit Register 51 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 BAUDCON ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 TXSTA Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous master transmission. Note 1: Reserved in 28-pin devices; always maintain these bits clear. DS39631E-page 218 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.3.2 EUSART SYNCHRONOUS MASTER RECEPTION 3. 4. 5. 6. Ensure bits, CREN and SREN, are clear. If interrupts are desired, set enable bit, RCIE. If 9-bit reception is desired, set bit, RX9. If a single reception is required, set bit, SREN. For continuous reception, set bit, CREN. 7. Interrupt flag bit, RCIF, will be set when reception is complete and an interrupt will be generated if the enable bit, RCIE, was set. 8. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. 9. Read the 8-bit received data by reading the RCREG register. 10. If any error occurred, clear the error by clearing bit, CREN. 11. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. Once Synchronous mode is selected, reception is enabled by setting either the Single Receive Enable bit, SREN (RCSTA<5>), or the Continuous Receive Enable bit, CREN (RCSTA<4>). Data is sampled on the RX pin on the falling edge of the clock. If enable bit, SREN, is set, only a single word is received. If enable bit, CREN, is set, the reception is continuous until CREN is cleared. If both bits are set, then CREN takes precedence. To set up a Synchronous Master Reception: 1. 2. Initialize the SPBRGH:SPBRG registers for the appropriate baud rate. Set or clear the BRG16 bit, as required, to achieve the desired baud rate. Enable the synchronous master serial port by setting bits, SYNC, SPEN and CSRC. FIGURE 18-13: SYNCHRONOUS RECEPTION (MASTER MODE, SREN) Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 RC7/RX/DT pin bit 0 bit 1 bit 2 bit 3 bit 4 bit 5 bit 6 bit 7 RC6/TX/CK pin (TXCKP = 0) RC6/TX/CK pin (TXCKP = 1) Write to bit SREN SREN bit CREN bit `0' `0' RCIF bit (Interrupt) Read RXREG Note: Timing diagram demonstrates Sync Master mode with bit, SREN = 1, and bit, BRGH = 0. TABLE 18-8: Name REGISTERS ASSOCIATED WITH SYNCHRONOUS MASTER RECEPTION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D RCSTA RCREG TXSTA EUSART Receive Register CSRC BAUDCON ABDOVF 51 51 TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous master reception. Note 1: Reserved in 28-pin devices; always maintain these bits clear. (c) 2008 Microchip Technology Inc. DS39631E-page 219 PIC18F2420/2520/4420/4520 18.4 To set up a Synchronous Slave Transmission: EUSART Synchronous Slave Mode 1. Synchronous Slave mode is entered by clearing bit, CSRC (TXSTA<7>). This mode differs from the Synchronous Master mode in that the shift clock is supplied externally at the CK pin (instead of being supplied internally in Master mode). This allows the device to transfer or receive data while in any low-power mode. 18.4.1 EUSART SYNCHRONOUS SLAVE TRANSMISSION 2. 3. 4. 5. 6. The operation of the Synchronous Master and Slave modes is identical, except in the case of the Sleep mode. 7. 8. If two words are written to the TXREG and then the SLEEP instruction is executed, the following will occur: a) b) c) d) e) Enable the synchronous slave serial port by setting bits, SYNC and SPEN, and clearing bit, CSRC. Clear bits, CREN and SREN. If interrupts are desired, set enable bit, TXIE. If 9-bit transmission is desired, set bit, TX9. Enable the transmission by setting enable bit, TXEN. If 9-bit transmission is selected, the ninth bit should be loaded in bit, TX9D. Start transmission by loading data to the TXREG register. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. The first word will immediately transfer to the TSR register and transmit. The second word will remain in the TXREG register. Flag bit, TXIF, will not be set. When the first word has been shifted out of TSR, the TXREG register will transfer the second word to the TSR and flag bit, TXIF, will now be set. If enable bit, TXIE, is set, the interrupt will wake the chip from Sleep. If the global interrupt is enabled, the program will branch to the interrupt vector. TABLE 18-9: Name REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE TRANSMISSION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INT0IE RBIE TMR0IF INT0IF RBIF 49 INTCON GIE/GIEH PEIE/GIEL TMR0IE PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCSTA TXREG TXSTA EUSART Transmit Register 51 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 BAUDCON ABDOVF SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous slave transmission. Note 1: Reserved in 28-pin devices; always maintain these bits clear. DS39631E-page 220 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 18.4.2 EUSART SYNCHRONOUS SLAVE RECEPTION To set up a Synchronous Slave Reception: 1. The operation of the Synchronous Master and Slave modes is identical, except in the case of Sleep, or any Idle mode and bit, SREN, which is a "don't care" in Slave mode. If receive is enabled by setting the CREN bit prior to entering Sleep or any Idle mode, then a word may be received while in this low-power mode. Once the word is received, the RSR register will transfer the data to the RCREG register; if the RCIE enable bit is set, the interrupt generated will wake the chip from the low-power mode. If the global interrupt is enabled, the program will branch to the interrupt vector. 2. 3. 4. 5. 6. 7. 8. 9. Enable the synchronous master serial port by setting bits, SYNC and SPEN, and clearing bit, CSRC. If interrupts are desired, set enable bit, RCIE. If 9-bit reception is desired, set bit, RX9. To enable reception, set enable bit, CREN. Flag bit, RCIF, will be set when reception is complete. An interrupt will be generated if enable bit, RCIE, was set. Read the RCSTA register to get the 9th bit (if enabled) and determine if any error occurred during reception. Read the 8-bit received data by reading the RCREG register. If any error occurred, clear the error by clearing bit, CREN. If using interrupts, ensure that the GIE and PEIE bits in the INTCON register (INTCON<7:6>) are set. TABLE 18-10: REGISTERS ASSOCIATED WITH SYNCHRONOUS SLAVE RECEPTION Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 PSPIE(1) ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 SPEN RX9 SREN CREN ADDEN FERR OERR RX9D 51 RCSTA RCREG TXSTA EUSART Receive Register 51 CSRC TX9 TXEN SYNC SENDB BRGH TRMT TX9D 51 BAUDCON ABDOVF RCIDL RXDTP TXCKP BRG16 -- WUE ABDEN 51 SPBRGH EUSART Baud Rate Generator Register High Byte 51 SPBRG EUSART Baud Rate Generator Register Low Byte 51 Legend: -- = unimplemented, read as `0'. Shaded cells are not used for synchronous slave reception. Note 1: Reserved in 28-pin devices; always maintain these bits clear. (c) 2008 Microchip Technology Inc. DS39631E-page 221 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 222 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 19.0 10-BIT ANALOG-TO-DIGITAL CONVERTER (A/D) MODULE The Analog-to-Digital (A/D) Converter module has 10 inputs for the 28-pin devices and 13 for the 40/44-pin devices. This module allows conversion of an analog input signal to a corresponding 10-bit digital number. The ADCON0 register, shown in Register 19-1, controls the operation of the A/D module. The ADCON1 register, shown in Register 19-2, configures the functions of the port pins. The ADCON2 register, shown in Register 19-3, configures the A/D clock source, programmed acquisition time and justification. The module has five registers: * * * * * A/D Result High Register (ADRESH) A/D Result Low Register (ADRESL) A/D Control Register 0 (ADCON0) A/D Control Register 1 (ADCON1) A/D Control Register 2 (ADCON2) REGISTER 19-1: ADCON0: A/D CONTROL REGISTER 0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 -- -- CHS3 CHS2 CHS1 CHS0 GO/DONE ADON bit 7 bit 0 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 bit 7-6 Unimplemented: Read as `0' bit 5-2 CHS<3:0>: Analog Channel Select bits 0000 = Channel 0 (AN0) 0001 = Channel 1 (AN1) 0010 = Channel 2 (AN2) 0011 = Channel 3 (AN3) 0100 = Channel 4 (AN4) 0101 = Channel 5 (AN5)(1,2) 0110 = Channel 6 (AN6)(1,2) 0111 = Channel 7 (AN7)(1,2) 1000 = Channel 8 (AN8) 1001 = Channel 9 (AN9) 1010 = Channel 10 (AN10) 1011 = Channel 11 (AN11) 1100 = Channel 12 (AN12) 1101 = Unimplemented)(2) 1110 = Unimplemented)(2) 1111 = Unimplemented)(2) bit 1 GO/DONE: A/D Conversion Status bit When ADON = 1: 1 = A/D conversion in progress 0 = A/D Idle bit 0 ADON: A/D On bit 1 = A/D Converter module is enabled 0 = A/D Converter module is disabled Note 1: 2: x = Bit is unknown These channels are not implemented on 28-pin devices. Performing a conversion on unimplemented channels will return a floating input measurement. (c) 2008 Microchip Technology Inc. DS39631E-page 223 PIC18F2420/2520/4420/4520 REGISTER 19-2: ADCON1: A/D CONTROL REGISTER 1 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-q(1) R/W-q(1) R/W-q(1) -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 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 PCFG3: PCFG0 AN6(2) AN5(2) AN4 AN3 AN2 AN1 AN0 PCFG<3:0>: A/D Port Configuration Control bits: AN7(2) bit 3-0 AN8 VCFG0: Voltage Reference Configuration bit (VREF+ source) 1 = VREF+ (AN3) 0 = VDD AN9 bit 4 AN10 VCFG1: Voltage Reference Configuration bit (VREF- source) 1 = VREF- (AN2) 0 = VSS AN11 Unimplemented: Read as `0' bit 5 AN12 bit 7-6 0000(1) 0001 0010 0011 0100 0101 0110 A A A D D D D D A A A A D D D D A A A A A D D D A A A A A A D D A A A A A A A D A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A A D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D D A D D D D D D D A A D D D D D D A A A D D D D D A A A A D D D D A A A A A D D D A A A A A A D D A A A A A A A D 0111(1) 1000 1001 1010 1011 1100 1101 1110 1111 A = Analog input Note 1: 2: x = Bit is unknown D = Digital I/O The POR value of the PCFG bits depends on the value of the PBADEN Configuration bit. When PBADEN = 1, PCFG<2:0> = 000; when PBADEN = 0, PCFG<2:0> = 111. AN5 through AN7 are available only on 40/44-pin devices. DS39631E-page 224 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 19-3: ADCON2: A/D CONTROL REGISTER 2 R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 ADFM -- ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0 bit 7 bit 0 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 bit 7 ADFM: A/D Result Format Select bit 1 = Right justified 0 = Left justified bit 6 Unimplemented: Read as `0' bit 5-3 ACQT<2:0>: A/D Acquisition Time Select bits 111 = 20 TAD 110 = 16 TAD 101 = 12 TAD 100 = 8 TAD 011 = 6 TAD 010 = 4 TAD 001 = 2 TAD 000 = 0 TAD(1) bit 2-0 ADCS<2:0>: A/D Conversion Clock Select bits 111 = FRC (clock derived from A/D RC oscillator)(1) 110 = FOSC/64 101 = FOSC/16 100 = FOSC/4 011 = FRC (clock derived from A/D RC oscillator)(1) 010 = FOSC/32 001 = FOSC/8 000 = FOSC/2 Note 1: x = Bit is unknown If the A/D FRC clock source is selected, a delay of one TCY (instruction cycle) is added before the A/D clock starts. This allows the SLEEP instruction to be executed before starting a conversion. (c) 2008 Microchip Technology Inc. DS39631E-page 225 PIC18F2420/2520/4420/4520 The analog reference voltage is software selectable to either the device's positive and negative supply voltage (VDD and VSS), or the voltage level on the RA3/AN3/ VREF+ and RA2/AN2/VREF-/CVREF pins. A device Reset forces all registers to their Reset state. This forces the A/D module to be turned off and any conversion in progress is aborted. Each port pin associated with the A/D Converter can be configured as an analog input, or as a digital I/O. The ADRESH and ADRESL registers contain the result of the A/D conversion. When the A/D conversion is complete, the result is loaded into the ADRESH:ADRESL register pair, the GO/DONE bit (ADCON0 register) is cleared and the A/D Interrupt Flag bit, ADIF, is set. The block diagram of the A/D module is shown in Figure 19-1. The A/D Converter has a unique feature of being able to operate while the device is in Sleep mode. To operate in Sleep, the A/D conversion clock must be derived from the A/D's internal RC oscillator. The output of the sample and hold is the input into the converter, which generates the result via successive approximation. FIGURE 19-1: A/D BLOCK DIAGRAM CHS<3:0> 1100 1011 1010 1001 (Input Voltage) Reference Voltage VREF+ VREF- AN9 AN8 AN7(1) 0110 AN6(1) 0101 AN5(1) 0100 AN4 0011 AN3 0001 VDD(2) AN10 0111 0010 VCFG<1:0> AN11 1000 VAIN 10-Bit A/D Converter AN12 0000 AN2 AN1 AN0 X0 X1 1X 0X VSS(2) Note 1: 2: Channels, AN5 through AN7, are not available on 28-pin devices. I/O pins have diode protection to VDD and VSS. DS39631E-page 226 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 Wait for A/D conversion to complete, by either: * Polling for the GO/DONE bit to be cleared OR * Waiting for the A/D interrupt Read A/D Result registers (ADRESH:ADRESL); clear bit, ADIF, if required. For next conversion, go to step 1 or step 2, as required. The A/D conversion time per bit is defined as TAD. A minimum wait of 2 TAD is required before the next acquisition starts. 6. 7. FIGURE 19-2: 3FFh 1. 3FEh FIGURE 19-3: 002h 001h 1023 LSB 1023.5 LSB 1022 LSB 1022.5 LSB 3 LSB Analog Input Voltage ANALOG INPUT MODEL VDD Rs VAIN 2 LSB 000h 2.5 LSB 3. 4. A/D TRANSFER FUNCTION 003h 0.5 LSB 2. Configure the A/D module: * Configure analog pins, voltage reference and digital I/O (ADCON1) * Select A/D input channel (ADCON0) * Select A/D acquisition time (ADCON2) * Select A/D conversion clock (ADCON2) * Turn on A/D module (ADCON0) Configure A/D interrupt (if desired): * Clear ADIF bit * Set ADIE bit * Set GIE bit Wait the required acquisition time (if required). Start conversion: * Set GO/DONE bit (ADCON0 register) Digital Code Output The following steps should be followed to perform an A/D conversion: 1 LSB After the A/D module has been configured as desired, the selected channel must be acquired before the conversion is started. The analog input channels must have their corresponding TRIS bits selected as an input. To determine acquisition time, see Section 19.1 "A/D Acquisition Requirements". After this acquisition time has elapsed, the A/D conversion can be started. An acquisition time can be programmed to occur between setting the GO/DONE bit and the actual start of the conversion. 5. 1.5 LSB The value in the ADRESH:ADRESL registers is not modified for a Power-on Reset. The ADRESH:ADRESL registers will contain unknown data after a Power-on Reset. ANx VT = 0.6V RIC 1k CPIN 5 pF Sampling Switch VT = 0.6V SS RSS ILEAKAGE 100 nA CHOLD = 25 pF VSS Legend: CPIN = Input Capacitance VT = Threshold Voltage ILEAKAGE = Leakage Current at the pin due to various junctions = Interconnect Resistance RIC = Sampling Switch SS = Sample/Hold Capacitance (from DAC) CHOLD RSS = Sampling Switch Resistance (c) 2008 Microchip Technology Inc. VDD 6V 5V 4V 3V 2V 1 2 3 4 Sampling Switch (k) DS39631E-page 227 PIC18F2420/2520/4420/4520 19.1 A/D Acquisition Requirements For the A/D Converter to meet its specified accuracy, the charge holding capacitor (CHOLD) must be allowed to fully charge to the input channel voltage level. The analog input model is shown in Figure 19-3. The source impedance (RS) and the internal sampling switch (RSS) impedance directly affect the time required to charge the capacitor CHOLD. The sampling switch (RSS) impedance varies over the device voltage (VDD). The source impedance affects the offset voltage at the analog input (due to pin leakage current). The maximum recommended impedance for analog sources is 2.5 k. After the analog input channel is selected (changed), the channel must be sampled for at least the minimum acquisition time before starting a conversion. EQUATION 19-1: CHOLD Rs Conversion Error VDD Temperature = = = = 25 pF 2.5 k 1/2 LSb 5V Rss = 2 k 85C (system max.) ACQUISITION TIME = Amplifier Settling Time + Holding Capacitor Charging Time + Temperature Coefficient = TAMP + TC + TCOFF EQUATION 19-2: VHOLD or TC Example 19-3 shows the calculation of the minimum required acquisition time TACQ. This calculation is based on the following application system assumptions: When the conversion is started, the holding capacitor is disconnected from the input pin. Note: TACQ To calculate the minimum acquisition time, Equation 19-1 may be used. This equation assumes that 1/2 LSb error is used (1024 steps for the A/D). The 1/2 LSb error is the maximum error allowed for the A/D to meet its specified resolution. A/D MINIMUM CHARGING TIME = (VREF - (VREF/2048)) * (1 - e(-TC/CHOLD(RIC + RSS + RS))) = -(CHOLD)(RIC + RSS + RS) ln(1/2048) EQUATION 19-3: CALCULATING THE MINIMUM REQUIRED ACQUISITION TIME TACQ = TAMP + TC + TCOFF TAMP = 0.2 s TCOFF = (Temp - 25C)(0.02 s/C) (85C - 25C)(0.02 s/C) 1.2 s Temperature coefficient is only required for temperatures > 25C. Below 25C, TCOFF = 0 s. TC = -(CHOLD)(RIC + RSS + RS) ln(1/2047) s -(25 pF) (1 k + 2 k + 2.5 k) ln(0.0004883) s 1.05 s TACQ = 0.2 s + 1 s + 1.2 s 2.4 s DS39631E-page 228 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 19.2 Selecting and Configuring Acquisition Time 19.3 Selecting the A/D Conversion Clock The ADCON2 register allows the user to select an acquisition time that occurs each time the GO/DONE bit is set. It also gives users the option to use an automatically determined acquisition time. The A/D conversion time per bit is defined as TAD. The A/D conversion requires 11 TAD per 10-bit conversion. The source of the A/D conversion clock is software selectable. There are seven possible options for TAD: Acquisition time may be set with the ACQT<2:0> bits (ADCON2<5:3>), which provides a range of 2 to 20 TAD. When the GO/DONE bit is set, the A/D module continues to sample the input for the selected acquisition time, then automatically begins a conversion. Since the acquisition time is programmed, there may be no need to wait for an acquisition time between selecting a channel and setting the GO/DONE bit. * * * * * * * Manual acquisition is selected when ACQT<2:0> = 000. When the GO/DONE bit is set, sampling is stopped and a conversion begins. The user is responsible for ensuring the required acquisition time has passed between selecting the desired input channel and setting the GO/DONE bit. This option is also the default Reset state of the ACQT<2:0> bits and is compatible with devices that do not offer programmable acquisition times. For correct A/D conversions, the A/D conversion clock (TAD) must be as short as possible, but greater than the minimum TAD (see parameter 130 for more information). 2 TOSC 4 TOSC 8 TOSC 16 TOSC 32 TOSC 64 TOSC Internal RC Oscillator Table 19-1 shows the resultant TAD times derived from the device operating frequencies and the A/D clock source selected. In either case, when the conversion is completed, the GO/DONE bit is cleared, the ADIF flag is set and the A/D begins sampling the currently selected channel again. If an acquisition time is programmed, there is nothing to indicate if the acquisition time has ended or if the conversion has begun. TABLE 19-1: TAD vs. DEVICE OPERATING FREQUENCIES AD Clock Source (TAD) Operation ADCS<2:0> PIC18F2X20/4X20 PIC18LF2X2X/4X20(4) 2 TOSC 000 2.86 MHz 1.43 kHz 4 TOSC 100 5.71 MHz 2.86 MHz 8 TOSC 001 11.43 MHz 5.72 MHz 16 TOSC 101 22.86 MHz 11.43 MHz 32 TOSC 010 40.0 MHz 22.86 MHz 64 TOSC 110 40.0 MHz 22.86 MHz RC(3) Note 1: 2: 3: 4: Maximum Device Frequency x11 1.00 MHz(1) 1.00 MHz(2) The RC source has a typical TAD time of 1.2 s. The RC source has a typical TAD time of 2.5 s. For device frequencies above 1 MHz, the device must be in Sleep for the entire conversion or the A/D accuracy may be out of specification. Low-power (PIC18LFXXXX) devices only. (c) 2008 Microchip Technology Inc. DS39631E-page 229 PIC18F2420/2520/4420/4520 19.4 Operation in Power-Managed Modes The selection of the automatic acquisition time and A/D conversion clock is determined in part by the clock source and frequency while in a power-managed mode. If the A/D is expected to operate while the device is in a power-managed mode, the ACQT<2:0> and ADCS<2:0> bits in ADCON2 should be updated in accordance with the clock source to be used in that mode. After entering the mode, an A/D acquisition or conversion may be started. Once started, the device should continue to be clocked by the same clock source until the conversion has been completed. If desired, the device may be placed into the corresponding Idle mode during the conversion. If the device clock frequency is less than 1 MHz, the A/D RC clock source should be selected. Operation in Sleep mode requires the A/D FRC clock to be selected. If the ACQT<2:0> bits are set to `000' and a conversion is started, the conversion will be delayed one instruction cycle to allow execution of the SLEEP instruction and entry to Sleep mode. The IDLEN bit (OSCCON<7>) must have already been cleared prior to starting the conversion. DS39631E-page 230 19.5 Configuring Analog Port Pins The ADCON1, TRISA, TRISB and TRISE registers all configure the A/D port pins. The port pins needed as analog inputs must have their corresponding TRIS bits set (input). If the TRIS bit is cleared (output), the digital output level (VOH or VOL) will be converted. The A/D operation is independent of the state of the CHS<3:0> bits and the TRIS bits. Note 1: When reading the PORT register, all pins configured as analog input channels will read as cleared (a low level). Pins configured as digital inputs will convert as analog inputs. Analog levels on a digitally configured input will be accurately converted. 2: Analog levels on any pin defined as a digital input may cause the digital input buffer to consume current out of the device's specification limits. 3: The PBADEN bit, in Configuration Register 3H, configures PORTB pins to reset as analog or digital pins by controlling how the PCFG bits in ADCON1 are reset. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 19.6 After the A/D conversion is completed or aborted, a 2 TAD wait is required before the next acquisition can be started. After this wait, acquisition on the selected channel is automatically started. A/D Conversions Figure 19-4 shows the operation of the A/D Converter after the GO/DONE bit has been set and the ACQT<2:0> bits are cleared. A conversion is started after the following instruction to allow entry into Sleep mode before the conversion begins. Figure 19-5 shows the operation of the A/D Converter after the GO/DONE bit has been set and the ACQT<2:0> bits are set to `010', and selecting a 4 TAD acquisition time before the conversion starts. 19.7 Discharge The discharge phase is used to initialize the value of the capacitor array. The array is discharged before every sample. This feature helps to optimize the unitygain amplifier, as the circuit always needs to charge the capacitor array, rather than charge/discharge based on previous measure values. Clearing the GO/DONE bit during a conversion will abort the current conversion. The A/D Result register pair will NOT be updated with the partially completed A/D conversion sample. This means the ADRESH:ADRESL registers will continue to contain the value of the last completed conversion (or the last value written to the ADRESH:ADRESL registers). FIGURE 19-4: The GO/DONE bit should NOT be set in the same instruction that turns on the A/D. Note: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 000, TACQ = 0) TCY - TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 TAD9 TAD10 TAD11 TAD1 b4 b1 b0 b6 b7 b2 b9 b8 b3 b5 Conversion starts Discharge Holding capacitor is disconnected from analog input (typically 100 ns) Set GO/DONE bit On the following cycle: ADRESH:ADRESL are loaded, GO/DONE bit is cleared, ADIF bit is set, holding capacitor is connected to analog input. FIGURE 19-5: A/D CONVERSION TAD CYCLES (ACQT<2:0> = 010, TACQ = 4 TAD) TAD Cycles TACQT Cycles 1 2 3 Automatic Acquisition Time 4 1 2 3 4 5 6 7 8 9 10 11 b9 b8 b7 b6 b5 b4 b3 b2 b1 b0 Conversion starts (Holding capacitor is disconnected) Set GO/DONE bit (Holding capacitor continues acquiring input) (c) 2008 Microchip Technology Inc. TAD1 Discharge On the following cycle: ADRESH:ADRESL are loaded, GO/DONE bit is cleared, ADIF bit is set, holding capacitor is connected to analog input. DS39631E-page 231 PIC18F2420/2520/4420/4520 19.8 Use of the CCP2 Trigger An A/D conversion can be started by the Special Event Trigger of the CCP2 module. This requires that the CCP2M<3:0> bits (CCP2CON<3:0>) be programmed as `1011' and that the A/D module is enabled (ADON bit is set). When the trigger occurs, the GO/DONE bit will be set, starting the A/D acquisition and conversion, and the Timer1 (or Timer3) counter will be reset to zero. Timer1 (or Timer3) is reset to automatically repeat the A/D acquisition period with minimal software overhead (moving ADRESH:ADRESL to the desired location). TABLE 19-2: Name The appropriate analog input channel must be selected and the minimum acquisition period is either timed by the user, or an appropriate TACQ time is selected before the Special Event Trigger sets the GO/DONE bit (starts a conversion). If the A/D module is not enabled (ADON is cleared), the Special Event Trigger will be ignored by the A/D module, but will still reset the Timer1 (or Timer3) counter. REGISTERS ASSOCIATED WITH A/D OPERATION Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page INTCON GIE/GIEH PEIE/GIEL TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR1 PSPIF(1) ADIF RCIF TXIF SSPIF CCP1IF TMR2IF TMR1IF 52 PIE1 (1) PSPIE ADIE RCIE TXIE SSPIE CCP1IE TMR2IE TMR1IE 52 IPR1 PSPIP(1) ADIP RCIP TXIP SSPIP CCP1IP TMR2IP TMR1IP 52 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 IPR2 ADRESH A/D Result Register High Byte ADRESL A/D Result Register Low Byte ADCON0 51 51 -- -- CHS3 CHS2 CHS1 CHS0 GO/DONE ADON 51 ADCON1 -- -- VCFG1 VCFG0 PCFG3 PCFG2 PCFG1 PCFG0 51 ADCON2 ADFM -- ACQT2 ACQT1 ACQT0 ADCS2 ADCS1 ADCS0 51 PORTA RA7(2) RA6(2) RA5 RA4 RA3 RA2 RA1 RA0 52 TRISA TRISA7(2) TRISA6(2) PORTB RB7 RB6 RB2 RB1 RB0 52 PORTA Data Direction Register RB5 RB4 RB3 TRISB PORTB Data Direction Register LATB PORTB Data Latch Register (Read and Write to Data Latch) 52 52 52 PORTE(4) -- -- -- -- RE3(3) RE2 RE1 RE0 52 TRISE(4) IBF OBF IBOV PSPMODE -- TRISE2 TRISE1 TRISE0 52 LATE(4) -- -- -- -- -- PORTE Data Latch Register 52 Legend: -- = unimplemented, read as `0'. Shaded cells are not used for A/D conversion. Note 1: These bits are unimplemented on 28-pin devices; always maintain these bits clear. 2: PORTA<7:6> and their direction bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits read as `0'. 3: RE3 port bit is available only as an input pin when the MCLRE Configuration bit is `0'. 4: These registers are not implemented on 28-pin devices. DS39631E-page 232 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 20.0 COMPARATOR MODULE The analog comparator module contains two comparators that can be configured in a variety of ways. The inputs can be selected from the analog inputs multiplexed with pins, RA0 through RA5, as well as the on-chip voltage reference (see Section 21.0 "Comparator Voltage Reference Module"). The digital outputs (normal or inverted) are available at the pin level and can also be read through the control register. REGISTER 20-1: R-0 C2OUT bit 7 The CMCON register (Register 20-1) selects the comparator input and output configuration. Block diagrams of the various comparator configurations are shown in Figure 20-1. CMCON: COMPARATOR CONTROL REGISTER R-0 R/W-0 R/W-0 R/W-0 R/W-1 R/W-1 C1OUT C2INV C1INV CIS CM2 CM1 R/W-1 CM0 bit 0 Legend: R = Readable bit -n = Value at POR W = Writable bit `1' = Bit is set bit 7 C2OUT: Comparator 2 Output bit When C2INV = 0: 1 = C2 VIN+ > C2 VIN0 = C2 VIN+ < C2 VINWhen C2INV = 1: 1 = C2 VIN+ < C2 VIN0 = C2 VIN+ > C2 VIN- bit 6 C1OUT: Comparator 1 Output bit When C1INV = 0: 1 = C1 VIN+ > C1 VIN0 = C1 VIN+ < C1 VINWhen C1INV = 1: 1 = C1 VIN+ < C1 VIN0 = C1 VIN+ > C1 VIN- bit 5 C2INV: Comparator 2 Output Inversion bit 1 = C2 output inverted 0 = C2 output not inverted C1INV: Comparator 1 Output Inversion bit 1 = C1 output inverted 0 = C1 output not inverted bit 4 bit 3 bit 2-0 U = Unimplemented bit, read as `0' `0' = Bit is cleared x = Bit is unknown CIS: Comparator Input Switch bit When CM<2:0> = 110: 1 = C1 VIN- connects to RA3/AN3/VREF+ C2 VIN- connects to RA2/AN2/VREF-/CVREF 0 = C1 VIN- connects to RA0/AN0 C2 VIN- connects to RA1/AN1 CM<2:0>: Comparator Mode bits Figure 20-1 shows the Comparator modes and the CM<2:0> bit settings. (c) 2008 Microchip Technology Inc. DS39631E-page 233 PIC18F2420/2520/4420/4520 20.1 Comparator Configuration There are eight modes of operation for the comparators, shown in Figure 20-1. Bits CM<2:0> of the CMCON register are used to select these modes. The TRISA register controls the data direction of the comparator pins for each mode. If the Comparator mode is FIGURE 20-1: Comparators Off (POR Default Value) CM<2:0> = 111 A VIN- RA3/AN3/ A VREF+ VIN+ A VIN- RA1/AN1 RA2/AN2/ A VREF-/CVREF VIN+ C1 Off (Read as `0') C2 Off (Read as `0') Two Independent Comparators CM<2:0> = 010 A VIN- RA3/AN3/ A VREF+ VIN+ A VIN- RA2/AN2/ A VREF-/CVREF VIN+ RA0/AN0 Comparator interrupts should be disabled during a Comparator mode change; otherwise, a false interrupt may occur. Note: COMPARATOR I/O OPERATING MODES Comparators Reset CM<2:0> = 000 RA0/AN0 changed, the comparator output level may not be valid for the specified mode change delay shown in Section 26.0 "Electrical Characteristics". C1 RA0/AN0 D VIN- RA3/AN3/ VREF+ D VIN+ RA1/AN1 D VIN- D RA2/AN2/ VREF-/CVREF VIN+ C1 Off (Read as `0') C2 Off (Read as `0') Two Independent Comparators with Outputs CM<2:0> = 011 C1OUT RA0/AN0 RA3/AN3/ VREF+ A VIN- A VIN+ C1 C1OUT C2 C2OUT RA4/T0CKI/C1OUT* RA1/AN1 C2 C2OUT A VIN- RA2/AN2/ A VREF-/CVREF VIN+ RA1/AN1 RA5/AN4/SS/HLVDIN/C2OUT* Two Common Reference Comparators CM<2:0> = 100 A VIN- RA3/AN3/ A VREF+ VIN+ A VIN- RA2/AN2/ D VREF-/CVREF VIN+ RA0/AN0 C1 Two Common Reference Comparators with Outputs CM<2:0> = 101 C1OUT RA0/AN0 RA3/AN3/ VREF+ A VIN- A VIN+ C1 C1OUT C2 C2OUT RA4/T0CKI/C1OUT* RA1/AN1 C2 C2OUT A VIN- RA2/AN2/ D VREF-/CVREF VIN+ RA1/AN1 RA5/AN4/SS/HLVDIN/C2OUT* One Independent Comparator with Output CM<2:0> = 001 A VIN- RA3/AN3/ A VREF+ VIN+ RA0/AN0 C1 C1OUT RA4/T0CKI/C1OUT* D VIN- RA2/AN2/ D VREF-/CVREF VIN+ RA1/AN1 Four Inputs Multiplexed to Two Comparators CM<2:0> = 110 RA0/AN0 A RA3/AN3/ VREF+ A RA1/AN1 A A RA2/AN2/ VREF-/CVREF C2 Off (Read as `0') CIS = 0 CIS = 1 VIN- CIS = 0 CIS = 1 VIN- VIN+ VIN+ C1 C1OUT C2 C2OUT CVREF From VREF Module A = Analog Input, port reads zeros always D = Digital Input CIS (CMCON<3>) is the Comparator Input Switch * Setting the TRISA<5:4> bits will disable the comparator outputs by configuring the pins as inputs. DS39631E-page 234 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 20.2 20.3.2 Comparator Operation A single comparator is shown in Figure 20-2, along with the relationship between the analog input levels and the digital output. When the analog input at VIN+ is less than the analog input VIN-, the output of the comparator is a digital low level. When the analog input at VIN+ is greater than the analog input VIN-, the output of the comparator is a digital high level. The shaded areas of the output of the comparator in Figure 20-2 represent the uncertainty, due to input offsets and response time. 20.3 Comparator Reference Depending on the comparator operating mode, either an external or internal voltage reference may be used. The analog signal present at VIN- is compared to the signal at VIN+ and the digital output of the comparator is adjusted accordingly (Figure 20-2). FIGURE 20-2: SINGLE COMPARATOR VIN+ + VIN- - Output VINVIN+ Output 20.3.1 INTERNAL REFERENCE SIGNAL The comparator module also allows the selection of an internally generated voltage reference from the comparator voltage reference module. This module is described in more detail in Section 21.0 "Comparator Voltage Reference Module". The internal reference is only available in the mode where four inputs are multiplexed to two comparators (CM<2:0> = 110). In this mode, the internal voltage reference is applied to the VIN+ pin of both comparators. 20.4 Comparator Response Time Response time is the minimum time, after selecting a new reference voltage or input source, before the comparator output has a valid level. If the internal reference is changed, the maximum delay of the internal voltage reference must be considered when using the comparator outputs. Otherwise, the maximum delay of the comparators should be used (see Section 26.0 "Electrical Characteristics"). 20.5 Comparator Outputs The comparator outputs are read through the CMCON register. These bits are read-only. The comparator outputs may also be directly output to the RA4 and RA5 I/O pins. When enabled, multiplexers in the output path of the RA4 and RA5 pins will switch and the output of each pin will be the unsynchronized output of the comparator. The uncertainty of each of the comparators is related to the input offset voltage and the response time given in the specifications. Figure 20-3 shows the comparator output block diagram. The TRISA bits will still function as an output enable/ disable for the RA4 and RA5 pins while in this mode. EXTERNAL REFERENCE SIGNAL When external voltage references are used, the comparator module can be configured to have the comparators operate from the same or different reference sources. However, threshold detector applications may require the same reference. The reference signal must be between VSS and VDD and can be applied to either pin of the comparator(s). (c) 2008 Microchip Technology Inc. The polarity of the comparator outputs can be changed using the C2INV and C1INV bits (CMCON<4:5>). Note 1: When reading the PORT register, all pins configured as analog inputs will read as `0'. Pins configured as digital inputs will convert an analog input according to the Schmitt Trigger input specification. 2: Analog levels on any pin defined as a digital input may cause the input buffer to consume more current than is specified. DS39631E-page 235 PIC18F2420/2520/4420/4520 + To RA4 or RA5 pin - Port pins COMPARATOR OUTPUT BLOCK DIAGRAM MULTIPLEX FIGURE 20-3: D Q Bus Data CxINV Read CMCON EN D Q EN CL From Other Comparator Reset 20.6 Comparator Interrupts The comparator interrupt flag is set whenever there is a change in the output value of either comparator. Software will need to maintain information about the status of the output bits, as read from CMCON<7:6>, to determine the actual change that occurred. The CMIF bit (PIR2<6>) is the Comparator Interrupt Flag. The CMIF bit must be reset by clearing it. Since it is also possible to write a `1' to this register, a simulated interrupt may be initiated. Both the CMIE bit (PIE2<6>) and the PEIE bit (INTCON<6>) must be set to enable the interrupt. In addition, the GIE bit (INTCON<7>) must also be set. If any of these bits are clear, the interrupt is not enabled, though the CMIF bit will still be set if an interrupt condition occurs. Note: If a change in the CMCON register (C1OUT or C2OUT) should occur when a read operation is being executed (start of the Q2 cycle), then the CMIF (PIR2<6>) interrupt flag may not get set. The user, in the Interrupt Service Routine, can clear the interrupt in the following manner: a) b) Set CMIF bit 20.7 Comparator Operation During Sleep When a comparator is active and the device is placed in Sleep mode, the comparator remains active and the interrupt is functional if enabled. This interrupt will wake-up the device from Sleep mode when enabled. Each operational comparator will consume additional current, as shown in the comparator specifications. To minimize power consumption while in Sleep mode, turn off the comparators (CM<2:0> = 111) before entering Sleep. If the device wakes up from Sleep, the contents of the CMCON register are not affected. 20.8 Effects of a Reset A device Reset forces the CMCON register to its Reset state, causing the comparator modules to be turned off (CM<2:0> = 111). However, the input pins (RA0 through RA3) are configured as analog inputs by default on device Reset. The I/O configuration for these pins is determined by the setting of the PCFG<3:0> bits (ADCON1<3:0>). Therefore, device current is minimized when analog inputs are present at Reset time. Any read or write of CMCON will end the mismatch condition. Clear flag bit, CMIF. A mismatch condition will continue to set flag bit, CMIF. Reading CMCON will end the mismatch condition and allow flag bit, CMIF, to be cleared. DS39631E-page 236 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 20.9 range by more than 0.6V in either direction, one of the diodes is forward biased and a latch-up condition may occur. A maximum source impedance of 10 k is recommended for the analog sources. Any external component connected to an analog input pin, such as a capacitor or a Zener diode, should have very little leakage current. Analog Input Connection Considerations A simplified circuit for an analog input is shown in Figure 20-4. Since the analog pins are connected to a digital output, they have reverse biased diodes to VDD and VSS. The analog input, therefore, must be between VSS and VDD. If the input voltage deviates from this FIGURE 20-4: COMPARATOR ANALOG INPUT MODEL VDD VT = 0.6V RS < 10k RIC Comparator Input AIN CPIN 5 pF VA VT = 0.6V ILEAKAGE 100 nA VSS CPIN VT ILEAKAGE RIC RS VA Legend: TABLE 20-1: Name CMCON CVRCON INTCON = = = = = = Input Capacitance Threshold Voltage Leakage Current at the pin due to various junctions Interconnect Resistance Source Impedance Analog Voltage REGISTERS ASSOCIATED WITH COMPARATOR MODULE Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51 CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51 TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 52 GIE/GIEH PEIE/GIEL PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OSCFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 RA7(1) RA6(1) RA5 RA4 RA3 RA2 RA1 RA0 52 LATA7(1) LATA6(1) PORTA LATA TRISA TRISA7 (1) PORTA Data Latch Register (Read and Write to Data Latch) TRISA6(1) PORTA Data Direction Register 52 52 Legend: -- = unimplemented, read as `0'. Shaded cells are unused by the comparator module. Note 1: PORTA<7:6> and their direction and latch bits are individually configured as port pins based on various primary oscillator modes. When disabled, these bits are read as `0'. (c) 2008 Microchip Technology Inc. DS39631E-page 237 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 238 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 21.0 COMPARATOR VOLTAGE REFERENCE MODULE The comparator voltage reference is a 16-tap resistor ladder network that provides a selectable reference voltage. Although its primary purpose is to provide a reference for the analog comparators, it may also be used independently of them. A block diagram of the module is shown in Figure 21-1. The resistor ladder is segmented to provide two ranges of CVREF values and has a power-down function to conserve power when the reference is not being used. The module's supply reference can be provided from either device VDD/VSS or an external voltage reference. is selected by the CVRR bit (CVRCON<5>). The primary difference between the ranges is the size of the steps selected by the CVREF Selection bits (CVR<3:0>), with one range offering finer resolution. The equations used to calculate the output of the comparator voltage reference are as follows: If CVRR = 1: CVREF = ((CVR<3:0>)/24) x CVRSRC If CVRR = 0: CVREF = (CVRSRC x 1/4) + (((CVR<3:0>)/32) x CVRSRC) Configuring the Comparator Voltage Reference The comparator reference supply voltage can come from either VDD and VSS, or the external VREF+ and VREF- that are multiplexed with RA2 and RA3. The voltage source is selected by the CVRSS bit (CVRCON<4>). The voltage reference module is controlled through the CVRCON register (Register 21-1). The comparator voltage reference provides two ranges of output voltage, each with 16 distinct levels. The range to be used The settling time of the comparator voltage reference must be considered when changing the CVREF output (see Table 26-3 in Section 26.0 "Electrical Characteristics"). 21.1 REGISTER 21-1: CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 CVREN CVROE(1) CVRR CVRSS CVR3 CVR2 CVR1 CVR0 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 CVREN: Comparator Voltage Reference Enable bit 1 = CVREF circuit powered on 0 = CVREF circuit powered down bit 6 CVROE: Comparator VREF Output Enable bit(1) 1 = CVREF voltage level is also output on the RA2/AN2/VREF-/CVREF pin 0 = CVREF voltage is disconnected from the RA2/AN2/VREF-/CVREF pin bit 5 CVRR: Comparator VREF Range Selection bit 1 = 0 to 0.667 CVRSRC, with CVRSRC/24 step size (low range) 0 = 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size (high range) bit 4 CVRSS: Comparator VREF Source Selection bit 1 = Comparator reference source, CVRSRC = (VREF+) - (VREF-) 0 = Comparator reference source, CVRSRC = VDD - VSS bit 3-0 CVR3:CVR0: Comparator VREF Value Selection bits (0 (CVR<3:0>) 15) When CVRR = 1: CVREF = ((CVR<3:0>)/24) * (CVRSRC) When CVRR = 0: CVREF = (CVRSRC/4) + ((CVR<3:0>)/32) * (CVRSRC) Note 1: CVROE overrides the TRISA<2> bit setting. (c) 2008 Microchip Technology Inc. DS39631E-page 239 PIC18F2420/2520/4420/4520 FIGURE 21-1: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM VREF+ VDD CVRSS = 1 8R CVRSS = 0 CVR<3:0> R CVREN R R 16-to-1 MUX R 16 Steps R CVREF R R CVRR VREF- 8R CVRSS = 1 CVRSS = 0 21.2 Voltage Reference Accuracy/Error The full range of voltage reference cannot be realized due to the construction of the module. The transistors on the top and bottom of the resistor ladder network (Figure 21-1) keep CVREF from approaching the reference source rails. The voltage reference is derived from the reference source; therefore, the CVREF output changes with fluctuations in that source. The tested absolute accuracy of the voltage reference can be found in Section 26.0 "Electrical Characteristics". 21.3 Operation During Sleep When the device wakes up from Sleep through an interrupt or a Watchdog Timer time-out, the contents of the CVRCON register are not affected. To minimize current consumption in Sleep mode, the voltage reference should be disabled. 21.4 Effects of a Reset A device Reset disables the voltage reference by clearing bit, CVREN (CVRCON<7>). This Reset also disconnects the reference from the RA2 pin by clearing bit, CVROE (CVRCON<6>) and selects the high-voltage range by clearing bit, CVRR (CVRCON<5>). The CVR value select bits are also cleared. 21.5 Connection Considerations The voltage reference module operates independently of the comparator module. The output of the reference generator may be connected to the RA2 pin if the CVROE bit is set. Enabling the voltage reference output onto RA2 when it is configured as a digital input will increase current consumption. Connecting RA2 as a digital output with CVRSS enabled will also increase current consumption. The RA2 pin can be used as a simple D/A output with limited drive capability. Due to the limited current drive capability, a buffer must be used on the voltage reference output for external connections to VREF. Figure 21-2 shows an example buffering technique. DS39631E-page 240 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 21-2: COMPARATOR VOLTAGE REFERENCE OUTPUT BUFFER EXAMPLE PIC18FXXXX CVREF Module R(1) Voltage Reference Output Impedance Note 1: TABLE 21-1: Name CVRCON CMCON TRISA + - RA2 CVREF Output R is dependent upon the comparator voltage reference configuration bits, CVRCON<3:0> and CVRCON<5>. REGISTERS ASSOCIATED WITH COMPARATOR VOLTAGE REFERENCE Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Reset Values on page CVREN CVROE CVRR CVRSS CVR3 CVR2 CVR1 CVR0 51 C2OUT C1OUT C2INV C1INV CIS CM2 CM1 CM0 51 TRISA7(1) TRISA6(1) PORTA Data Direction Register 52 Legend: Shaded cells are not used with the comparator voltage reference. Note 1: PORTA pins are enabled based on oscillator configuration. (c) 2008 Microchip Technology Inc. DS39631E-page 241 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 242 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 22.0 HIGH/LOW-VOLTAGE DETECT (HLVD) PIC18F2420/2520/4420/4520 devices have a High/Low-Voltage Detect module (HLVD). This is a programmable circuit that allows the user to specify both a device voltage trip point and the direction of change from that point. If the device experiences an excursion past the trip point in that direction, an interrupt flag is set. If the interrupt is enabled, the program execution will branch to the interrupt vector address and the software can then respond to the interrupt. REGISTER 22-1: R/W-0 The block diagram for the HLVD module is shown in Figure 22-1. HLVDCON: HIGH/LOW-VOLTAGE DETECT CONTROL REGISTER U-0 VDIRMAG The High/Low-Voltage Detect Control register (Register 22-1) completely controls the operation of the HLVD module. This allows the circuitry to be "turned off" by the user under software control, which minimizes the current consumption for the device. R-0 -- IRVST R/W-0 R/W-0 R/W-1 R/W-0 R/W-1 HLVDEN HLVDL3(1) HLVDL2(1) HLVDL1(1) HLVDL0(1) 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 VDIRMAG: Voltage Direction Magnitude Select bit 1 = Event occurs when voltage equals or exceeds trip point (HLVDL<3:0>) 0 = Event occurs when voltage equals or falls below trip point (HLVDL<3:0>) bit 6 Unimplemented: Read as `0' bit 5 IRVST: Internal Reference Voltage Stable Flag bit 1 = Indicates that the voltage detect logic will generate the interrupt flag at the specified voltage range 0 = Indicates that the voltage detect logic will not generate the interrupt flag at the specified voltage range and the HLVD interrupt should not be enabled bit 4 HLVDEN: High/Low-Voltage Detect Power Enable bit 1 = HLVD enabled 0 = HLVD disabled bit 3-0 HLVDL<3:0>: Voltage Detection Limit bits(1) 1111 = External analog input is used (input comes from the HLVDIN pin) 1110 = Maximum setting . . . 0000 = Minimum setting Note 1: See Table 26-4 for specifications. (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 243 PIC18F2420/2520/4420/4520 The module is enabled by setting the HLVDEN bit. Each time that the HLVD module is enabled, the circuitry requires some time to stabilize. The IRVST bit is a read-only bit and is used to indicate when the circuit is stable. The module can only generate an interrupt after the circuit is stable and IRVST is set. event, depending on the configuration of the module. When the supply voltage is equal to the trip point, the voltage tapped off of the resistor array is equal to the internal reference voltage generated by the voltage reference module. The comparator then generates an interrupt signal by setting the HLVDIF bit. The VDIRMAG bit determines the overall operation of the module. When VDIRMAG is cleared, the module monitors for drops in VDD below a predetermined set point. When the bit is set, the module monitors for rises in VDD above the set point. The trip point voltage is software programmable to any one of 16 values. The trip point is selected by programming the HLVDL<3:0> bits (HLVDCON<3:0>). 22.1 Operation When the HLVD module is enabled, a comparator uses an internally generated reference voltage as the set point. The set point is compared with the trip point, where each node in the resistor divider represents a trip point voltage. The "trip point" voltage is the voltage level at which the device detects a high or low-voltage FIGURE 22-1: VDD The HLVD module has an additional feature that allows the user to supply the trip voltage to the module from an external source. This mode is enabled when bits, HLVDL<3:0>, are set to `1111'. In this state, the comparator input is multiplexed from the external input pin, HLVDIN. This gives users flexibility because it allows them to configure the High/Low-Voltage Detect interrupt to occur at any voltage in the valid operating range. HLVD MODULE BLOCK DIAGRAM (WITH EXTERNAL INPUT) Externally Generated Trip Point VDD HLVDCON Register HLVDEN HLVDIN 16-to-1 MUX HLVDIN HLVDL<3:0> VDIRMAG Set HLVDIF HLVDEN BOREN DS39631E-page 244 Internal Voltage Reference Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 22.2 HLVD Setup The following steps are needed to set up the HLVD module: 1. 2. 3. 4. 5. Write the value to the HLVDL<3:0> bits that selects the desired HLVD trip point. Set the VDIRMAG bit to detect high voltage (VDIRMAG = 1) or low voltage (VDIRMAG = 0). Enable the HLVD module by setting the HLVDEN bit. Clear the HLVD interrupt flag (PIR2<2>), which may have been set from a previous interrupt. Enable the HLVD interrupt, if interrupts are desired, by setting the HLVDIE and GIE bits (PIE2<2> and INTCON<7>). An interrupt will not be generated until the IRVST bit is set. 22.3 22.4 Current Consumption When the module is enabled, the HLVD comparator and voltage divider are enabled and will consume static current. The total current consumption, when enabled, is specified in electrical specification parameter D022B. FIGURE 22-2: Depending on the application, the HLVD module does not need to be operating constantly. To decrease the current requirements, the HLVD circuitry may only need to be enabled for short periods where the voltage is checked. After doing the check, the HLVD module may be disabled. HLVD Start-up Time The internal reference voltage of the HLVD module, specified in electrical specification parameter D420, may be used by other internal circuitry, such as the programmable Brown-out Reset. If the HLVD or other circuits using the voltage reference are disabled to lower the device's current consumption, the reference voltage circuit will require time to become stable before a low or high-voltage condition can be reliably detected. This start-up time, TIRVST, is an interval that is independent of device clock speed. It is specified in electrical specification parameter 36. The HLVD interrupt flag is not enabled until TIRVST has expired and a stable reference voltage is reached. For this reason, brief excursions beyond the set point may not be detected during this interval (refer to Figure 22-2 or Figure 22-3). LOW-VOLTAGE DETECT OPERATION (VDIRMAG = 0) CASE 1: HLVDIF may not be set VDD VLVD HLVDIF Enable HLVD TIRVST IRVST Internal Reference is Stable HLVDIF Cleared in Software CASE 2: VDD VLVD HLVDIF Enable HLVD TIRVST IRVST Internal Reference is Stable HLVDIF Cleared in Software HLVDIF cleared in software, HLVDIF remains set since HLVD condition still exists (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 245 PIC18F2420/2520/4420/4520 FIGURE 22-3: HIGH-VOLTAGE DETECT OPERATION (VDIRMAG = 1) CASE 1: HLVDIF may not be set VLVD VDD HLVDIF Enable HLVD TIRVST IRVST HLVDIF Cleared in Software Internal Reference is Stable CASE 2: VLVD VDD HLVDIF Enable HLVD TIRVST IRVST Internal Reference is Stable HLVDIF Cleared in Software HLVDIF cleared in software, HLVDIF remains set since HLVD condition still exists FIGURE 22-4: Applications In many applications, the ability to detect a drop below, or rise above, a particular threshold is desirable. For example, the HLVD module could be periodically enabled to detect Universal Serial Bus (USB) attach or detach. This assumes the device is powered by a lower voltage source than the USB when detached. An attach would indicate a high-voltage detect from, for example, 3.3V to 5V (the voltage on USB) and vice versa for a detach. This feature could save a design a few extra components and an attach signal (input pin). For general battery applications, Figure 22-4 shows a possible voltage curve. Over time, the device voltage decreases. When the device voltage reaches voltage, VA, the HLVD logic generates an interrupt at time, TA. The interrupt could cause the execution of an ISR, which would allow the application to perform "housekeeping tasks" and perform a controlled shutdown before the device voltage exits the valid operating range at TB. The HLVD, thus, would give the application a time window, represented by the difference between TA and TB, to safely exit. DS39631E-page 246 TYPICAL LOW-VOLTAGE DETECT APPLICATION VA VB Voltage 22.5 Time TA TB Legend: VA = HLVD trip point VB = Minimum valid device operating voltage Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 22.6 Operation During Sleep 22.7 When enabled, the HLVD circuitry continues to operate during Sleep. If the device voltage crosses the trip point, the HLVDIF bit will be set and the device will wake-up from Sleep. Device execution will continue from the interrupt vector address if interrupts have been globally enabled. TABLE 22-1: Effects of a Reset A device Reset forces all registers to their Reset state. This forces the HLVD module to be turned off. REGISTERS ASSOCIATED WITH HIGH/LOW-VOLTAGE DETECT MODULE Name Bit 7 Bit 6 HLVDCON VDIRMAG -- INTCON GIE/GIEH PEIE/GIEL Reset Values on Page Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 IRVST HLVDEN HLVDL3 HLVDL2 HLVDL1 HLVDL0 50 TMR0IE INT0IE RBIE TMR0IF INT0IF RBIF 49 PIR2 OSCFIF CMIF -- EEIF BCLIF HLVDIF TMR3IF CCP2IF 52 PIE2 OCSFIE CMIE -- EEIE BCLIE HLVDIE TMR3IE CCP2IE 52 IPR2 OSCFIP CMIP -- EEIP BCLIP HLVDIP TMR3IP CCP2IP 52 Legend: -- = unimplemented, read as `0'. Shaded cells are unused by the HLVD module. (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 247 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 248 Advance Information (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 23.0 SPECIAL FEATURES OF THE CPU PIC18F2420/2520/4420/4520 devices include several features intended to maximize reliability and minimize cost through elimination of external components. These are: * Oscillator Selection * Resets: - Power-on Reset (POR) - Power-up Timer (PWRT) - Oscillator Start-up Timer (OST) - Brown-out Reset (BOR) * Interrupts * Watchdog Timer (WDT) * Fail-Safe Clock Monitor * Two-Speed Start-up * Code Protection * ID Locations * In-Circuit Serial Programming All of these features are enabled and configured by setting the appropriate Configuration register bits. 23.1 Configuration Bits The Configuration bits can be programmed (read as `0') or left unprogrammed (read as `1') to select various device configurations. These bits are mapped starting at program memory location, 300000h. The user will note that address 300000h is beyond the user program memory space. In fact, it belongs to the configuration memory space (300000h-3FFFFFh), which can only be accessed using table reads and table writes. The oscillator can be configured for the application depending on frequency, power, accuracy and cost. All of the options are discussed in detail in Section 2.0 "Oscillator Configurations". A complete discussion of device Resets and interrupts is available in previous sections of this data sheet. In addition to their Power-up and Oscillator Start-up Timers provided for Resets, PIC18F2420/2520/4420/ 4520 devices have a Watchdog Timer, which is either permanently enabled via the Configuration bits or software controlled (if configured as disabled). TABLE 23-1: The inclusion of an internal RC oscillator also provides the additional benefits of a Fail-Safe Clock Monitor (FSCM) and Two-Speed Start-up. FSCM provides for background monitoring of the peripheral clock and automatic switchover in the event of its failure. TwoSpeed Start-up enables code to be executed almost immediately on start-up, while the primary clock source completes its start-up delays. Programming the Configuration registers is done in a manner similar to programming the Flash memory. The WR bit in the EECON1 register starts a self-timed write to the Configuration register. In normal operation mode, a TBLWT instruction with the TBLPTR pointing to the Configuration register sets up the address and the data for the Configuration register write. Setting the WR bit starts a long write to the Configuration register. The Configuration registers are written a byte at a time. To write or erase a configuration cell, a TBLWT instruction can write a `1' or a `0' into the cell. For additional details on Flash programming, refer to Section 6.5 "Writing to Flash Program Memory". CONFIGURATION BITS AND DEVICE IDs File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 FOSC1 FOSC0 Default/ Unprogrammed Value 300001h CONFIG1H IESO FCMEN -- -- FOSC3 FOSC2 300002h CONFIG2L -- -- -- BORV1 BORV0 BOREN1 -- -- -- WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN -- -- -- -- LPT1OSC PBADEN CCP2MX 1--- -011 10-- -1-1 BOREN0 PWRTEN 00-- 0111 ---1 1111 300003h CONFIG2H 300005h CONFIG3H MCLRE 300006h CONFIG4L DEBUG XINST -- -- -- LVP -- STVREN 300008h CONFIG5L -- -- -- -- CP3(1) CP2(1) CP1 CP0 ---- 1111 300009h CONFIG5H CPD CPB -- -- -- -- -- -- 11-- ---- 30000Ah CONFIG6L -- -- -- -- WRT3(1) WRT2(1) WRT1 WRT0 ---- 1111 30000Bh CONFIG6H WRTD WRTB WRTC -- -- -- -- -- 111- ---- (1) (1) ---1 1111 30000Ch CONFIG7L -- -- -- -- EBTR1 EBTR0 ---- 1111 30000Dh CONFIG7H -- EBTRB -- -- -- -- -- -- -1-- ---- 3FFFFEh DEVID1 DEV2 DEV1 DEV0 REV4 REV3 REV2 REV1 REV0 xxxx xxxx(2) 3FFFFFh DEVID2 DEV10 DEV9 DEV8 DEV7 DEV6 DEV5 DEV4 DEV3 xxxx xxxx(2) Legend: x = unknown, u = unchanged, -- = unimplemented, q = value depends on condition. Shaded cells are unimplemented, read as `0'. Unimplemented in PIC18F2420/4420 devices; maintain this bit set. See Register 23-12 for DEVID1 values. DEVID registers are read-only and cannot be programmed by the user. Note 1: 2: (c) 2008 Microchip Technology Inc. EBTR3 EBTR2 DS39631E-page 249 PIC18F2420/2520/4420/4520 REGISTER 23-1: CONFIG1H: CONFIGURATION REGISTER 1 HIGH (BYTE ADDRESS 300001h) R/P-0 R/P-0 U-0 U-0 R/P-0 R/P-1 R/P-1 R/P-1 IESO FCMEN -- -- FOSC3 FOSC2 FOSC1 FOSC0 bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 IESO: Internal/External Oscillator Switchover bit 1 = Oscillator Switchover mode enabled 0 = Oscillator Switchover mode disabled bit 6 FCMEN: Fail-Safe Clock Monitor Enable bit 1 = Fail-Safe Clock Monitor enabled 0 = Fail-Safe Clock Monitor disabled bit 5-4 Unimplemented: Read as `0' bit 3-0 FOSC<3:0>: Oscillator Selection bits 11xx = External RC oscillator, CLKO function on RA6 101x = External RC oscillator, CLKO function on RA6 1001 = Internal oscillator block, CLKO function on RA6; port function on RA7 1000 = Internal oscillator block, port function on RA6 and RA7 0111 = External RC oscillator, port function on RA6 0110 = HS oscillator, PLL enabled (Clock Frequency = 4 x FOSC1) 0101 = EC oscillator, port function on RA6 0100 = EC oscillator, CLKO function on RA6 0011 = External RC oscillator, CLKO function on RA6 0010 = HS oscillator 0001 = XT oscillator 0000 = LP oscillator DS39631E-page 250 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 23-2: U-0 CONFIG2L: CONFIGURATION REGISTER 2 LOW (BYTE ADDRESS 300002h) U-0 -- -- U-0 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 -- BORV1(1) BORV0(1) BOREN1(2) BOREN0(2) PWRTEN(2) bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7-5 Unimplemented: Read as `0' bit 4-3 BORV<1:0>: Brown-out Reset Voltage bits(1) 11 = Minimum setting . . . 00 = Maximum setting bit 2-1 BOREN<1:0>: Brown-out Reset Enable bits(2) 11 = Brown-out Reset enabled in hardware only (SBOREN is disabled) 10 = Brown-out Reset enabled in hardware only and disabled in Sleep mode (SBOREN is disabled) 01 = Brown-out Reset enabled and controlled by software (SBOREN is enabled) 00 = Brown-out Reset disabled in hardware and software bit 0 PWRTEN: Power-up Timer Enable bit(2) 1 = PWRT disabled 0 = PWRT enabled Note 1: 2: See Section 26.1 "DC Characteristics: Supply Voltage" for specifications. The Power-up Timer is decoupled from Brown-out Reset, allowing these features to be independently controlled. (c) 2008 Microchip Technology Inc. DS39631E-page 251 PIC18F2420/2520/4420/4520 REGISTER 23-3: CONFIG2H: CONFIGURATION REGISTER 2 HIGH (BYTE ADDRESS 300003h) U-0 U-0 U-0 R/P-1 R/P-1 R/P-1 R/P-1 R/P-1 -- -- -- WDTPS3 WDTPS2 WDTPS1 WDTPS0 WDTEN bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7-5 Unimplemented: Read as `0' bit 4-1 WDTPS<3:0>: Watchdog Timer Postscale Select bits 1111 = 1:32,768 1110 = 1:16,384 1101 = 1:8,192 1100 = 1:4,096 1011 = 1:2,048 1010 = 1:1,024 1001 = 1:512 1000 = 1:256 0111 = 1:128 0110 = 1:64 0101 = 1:32 0100 = 1:16 0011 = 1:8 0010 = 1:4 0001 = 1:2 0000 = 1:1 bit 0 WDTEN: Watchdog Timer Enable bit 1 = WDT enabled 0 = WDT disabled (control is placed on the SWDTEN bit) DS39631E-page 252 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 23-4: CONFIG3H: CONFIGURATION REGISTER 3 HIGH (BYTE ADDRESS 300005h) R/P-1 U-0 U-0 U-0 U-0 R/P-0 R/P-1 R/P-1 MCLRE -- -- -- -- LPT1OSC PBADEN CCP2MX bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 MCLRE: MCLR Pin Enable bit 1 = MCLR pin enabled; RE3 input pin disabled 0 = RE3 input pin enabled; MCLR disabled bit 6-3 Unimplemented: Read as `0' bit 2 LPT1OSC: Low-Power Timer1 Oscillator Enable bit 1 = Timer1 configured for low-power operation 0 = Timer1 configured for higher power operation bit 1 PBADEN: PORTB A/D Enable bit (Affects ADCON1 Reset state. ADCON1 controls PORTB<4:0> pin configuration.) 1 = PORTB<4:0> pins are configured as analog input channels on Reset 0 = PORTB<4:0> pins are configured as digital I/O on Reset bit 0 CCP2MX: CCP2 MUX bit 1 = CCP2 input/output is multiplexed with RC1 0 = CCP2 input/output is multiplexed with RB3 REGISTER 23-5: CONFIG4L: CONFIGURATION REGISTER 4 LOW (BYTE ADDRESS 300006h) R/P-1 R/P-0 U-0 U-0 U-0 R/P-1 U-0 R/P-1 DEBUG XINST -- -- -- LVP -- STVREN bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 DEBUG: Background Debugger Enable bit 1 = Background debugger disabled, RB6 and RB7 configured as general purpose I/O pins 0 = Background debugger enabled, RB6 and RB7 are dedicated to In-Circuit Debug bit 6 XINST: Extended Instruction Set Enable bit 1 = Instruction set extension and Indexed Addressing mode enabled 0 = Instruction set extension and Indexed Addressing mode disabled (Legacy mode) bit 5-3 Unimplemented: Read as `0' bit 2 LVP: Single-Supply ICSPTM Enable bit 1 = Single-Supply ICSP enabled 0 = Single-Supply ICSP disabled bit 1 Unimplemented: Read as `0' bit 0 STVREN: Stack Full/Underflow Reset Enable bit 1 = Stack full/underflow will cause Reset 0 = Stack full/underflow will not cause Reset (c) 2008 Microchip Technology Inc. DS39631E-page 253 PIC18F2420/2520/4420/4520 REGISTER 23-6: U-0 CONFIG5L: CONFIGURATION REGISTER 5 LOW (BYTE ADDRESS 300008h) U-0 -- -- U-0 -- U-0 -- R/C-1 R/C-1 (1) (1) CP3 CP2 R/C-1 R/C-1 CP1 CP0 bit 7 bit 0 Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' -n = Value when device is unprogrammed u = Unchanged from programmed state bit 7-4 Unimplemented: Read as `0' bit 3 CP3: Code Protection bit(1) 1 = Block 3 (006000-007FFFh) not code-protected 0 = Block 3 (006000-007FFFh) code-protected bit 2 CP2: Code Protection bit(1) 1 = Block 2 (004000-005FFFh) not code-protected 0 = Block 2 (004000-005FFFh) code-protected bit 1 CP1: Code Protection bit 1 = Block 1 (002000-003FFFh) not code-protected 0 = Block 1 (002000-003FFFh) code-protected bit 0 CP0: Code Protection bit 1 = Block 0 (000800-001FFFh) not code-protected 0 = Block 0 (000800-001FFFh) code-protected Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set. REGISTER 23-7: CONFIG5H: CONFIGURATION REGISTER 5 HIGH (BYTE ADDRESS 300009h) R/C-1 R/C-1 U-0 U-0 U-0 U-0 U-0 U-0 CPD CPB -- -- -- -- -- -- bit 7 bit 0 Legend: R = Readable bit C = Clearable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 CPD: Data EEPROM Code Protection bit 1 = Data EEPROM not code-protected 0 = Data EEPROM code-protected bit 6 CPB: Boot Block Code Protection bit 1 = Boot block (000000-0007FFh) not code-protected 0 = Boot block (000000-0007FFh) code-protected bit 5-0 Unimplemented: Read as `0' DS39631E-page 254 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 23-8: U-0 CONFIG6L: CONFIGURATION REGISTER 6 LOW (BYTE ADDRESS 30000Ah) U-0 -- -- U-0 -- U-0 -- R/C-1 WRT3 (1) R/C-1 (1) WRT2 R/C-1 R/C-1 WRT1 WRT0 bit 7 bit 0 Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' -n = Value when device is unprogrammed u = Unchanged from programmed state bit 7-4 Unimplemented: Read as `0' bit 3 WRT3: Write Protection bit(1) 1 = Block 3 (006000-007FFFh) not write-protected 0 = Block 3 (006000-007FFFh) write-protected bit 2 WRT2: Write Protection bit(1) 1 = Block 2 (004000-005FFFh) not write-protected 0 = Block 2 (004000-005FFFh) write-protected bit 1 WRT1: Write Protection bit 1 = Block 1 (002000-003FFFh) not write-protected 0 = Block 1 (002000-003FFFh) write-protected bit 0 WRT0: Write Protection bit 1 = Block 0 (000800-001FFFh) not write-protected 0 = Block 0 (000800-001FFFh) write-protected Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set. REGISTER 23-9: R/C-1 WRTD CONFIG6H: CONFIGURATION REGISTER 6 HIGH (BYTE ADDRESS 30000Bh) R/C-1 R/C-1 U-0 U-0 U-0 U-0 U-0 WRTB WRTC(1) -- -- -- -- -- bit 7 bit 0 Legend: R = Readable bit C = Clearable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 WRTD: Data EEPROM Write Protection bit 1 = Data EEPROM not write-protected 0 = Data EEPROM write-protected bit 6 WRTB: Boot Block Write Protection bit 1 = Boot block (000000-0007FFh) not write-protected 0 = Boot block (000000-0007FFh) write-protected bit 5 WRTC: Configuration Register Write Protection bit(1) 1 = Configuration registers (300000-3000FFh) not write-protected 0 = Configuration registers (300000-3000FFh) write-protected bit 4-0 Unimplemented: Read as `0' Note 1: This bit is read-only in normal execution mode; it can be written only in Program mode. (c) 2008 Microchip Technology Inc. DS39631E-page 255 PIC18F2420/2520/4420/4520 REGISTER 23-10: CONFIG7L: CONFIGURATION REGISTER 7 LOW (BYTE ADDRESS 30000Ch) U-0 U-0 U-0 U-0 R/C-1 R/C-1 R/C-1 R/C-1 -- -- -- -- EBTR3(1) EBTR2(1) EBTR1 EBTR0 bit 7 bit 0 Legend: R = Readable bit C = Clearable bit U = Unimplemented bit, read as `0' -n = Value when device is unprogrammed u = Unchanged from programmed state bit 7-4 Unimplemented: Read as `0' bit 3 EBTR3: Table Read Protection bit(1) 1 = Block 3 (006000-007FFFh) not protected from table reads executed in other blocks 0 = Block 3 (006000-007FFFh) protected from table reads executed in other blocks bit 2 EBTR2: Table Read Protection bit(1) 1 = Block 2 (004000-005FFFh) not protected from table reads executed in other blocks 0 = Block 2 (004000-005FFFh) protected from table reads executed in other blocks bit 1 EBTR1: Table Read Protection bit 1 = Block 1 (002000-003FFFh) not protected from table reads executed in other blocks 0 = Block 1 (002000-003FFFh) protected from table reads executed in other blocks bit 0 EBTR0: Table Read Protection bit 1 = Block 0 (000800-001FFFh) not protected from table reads executed in other blocks 0 = Block 0 (000800-001FFFh) protected from table reads executed in other blocks Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set. REGISTER 23-11: CONFIG7H: CONFIGURATION REGISTER 7 HIGH (BYTE ADDRESS 30000Dh) U-0 R/C-1 U-0 U-0 U-0 U-0 U-0 U-0 -- EBTRB -- -- -- -- -- -- bit 7 bit 0 Legend: R = Readable bit C = Clearable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7 Unimplemented: Read as `0' bit 6 EBTRB: Boot Block Table Read Protection bit 1 = Boot block (000000-0007FFh) not protected from table reads executed in other blocks 0 = Boot block (000000-0007FFh) protected from table reads executed in other blocks bit 5-0 Unimplemented: Read as `0' DS39631E-page 256 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 23-12: DEVID1: DEVICE ID REGISTER 1 FOR PIC18F2420/2520/4420/4520 R R R R R R R R DEV2 DEV1 DEV0 REV4 REV3 REV2 REV1 REV0 bit 7 bit 0 Legend: R = Readable bit P = Programmable bit -n = Value when device is unprogrammed U = Unimplemented bit, read as `0' u = Unchanged from programmed state bit 7-5 DEV<2:0>: Device ID bits 110 = PIC18F4420 100 = PIC18F4520 010 = PIC18F2420 000 = PIC18F2520 bit 4-0 REV<4:0>: Revision ID bits These bits are used to indicate the device revision. REGISTER 23-13: DEVID2: DEVICE ID REGISTER 2 FOR PIC18F2420/2520/4420/4520 R R R R R R R R DEV10(1) DEV9(1) DEV8(1) DEV7(1) DEV6(1) DEV5(1) DEV4(1) DEV3(1) bit 7 bit 0 Legend: R = Read-only bit P = Programmable bit -n = Value when device is unprogrammed bit 7-0 Note 1: U = Unimplemented bit, read as `0' u = Unchanged from programmed state DEV<10:3>: Device ID bits(1) These bits are used with the DEV<2:0> bits in Device ID Register 1 to identify the part number. 0001 0001 = PIC18F2420/2520 devices 0001 0000 = PIC18F4420/4520 devices These values for DEV<10:3> may be shared with other devices. The specific device is always identified by using the entire DEV<10:0> bit sequence. (c) 2008 Microchip Technology Inc. DS39631E-page 257 PIC18F2420/2520/4420/4520 23.2 Watchdog Timer (WDT) For PIC18F2420/2520/4420/4520 devices, the WDT is driven by the INTRC source. When the WDT is enabled, the clock source is also enabled. The nominal WDT period is 4 ms and has the same stability as the INTRC oscillator. The 4 ms period of the WDT is multiplied by a 16-bit postscaler. Any output of the WDT postscaler is selected by a multiplexer, controlled by bits in Configuration Register 2H. Available periods range from 4 ms to 131.072 seconds (2.18 minutes). The WDT and postscaler are cleared when any of the following events occur: a SLEEP or CLRWDT instruction is executed, the IRCF bits (OSCCON<6:4>) are changed or a clock failure has occurred. FIGURE 23-1: Note 1: The CLRWDT and SLEEP instructions clear the WDT and postscaler counts when executed. 2: Changing the setting of the IRCF bits (OSCCON<6:4>) clears the WDT and postscaler counts. 3: When a CLRWDT instruction is executed, the postscaler count will be cleared. 23.2.1 CONTROL REGISTER Register 23-14 shows the WDTCON register. This is a readable and writable register which contains a control bit that allows software to override the WDT enable Configuration bit, but only if the Configuration bit has disabled the WDT. WDT BLOCK DIAGRAM SWDTEN WDTEN Enable WDT WDT Counter INTRC Source Wake-up from Power-Managed Modes /128 Change on IRCF bits Programmable Postscaler 1:1 to 1:32,768 CLRWDT Reset WDT Reset All Device Resets WDTPS<3:0> 4 Sleep DS39631E-page 258 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 REGISTER 23-14: WDTCON: WATCHDOG TIMER CONTROL REGISTER U-0 U-0 U-0 U-0 U-0 U-0 U-0 R/W-0 -- -- -- -- -- -- -- SWDTEN(1) 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 bit 7-1 Unimplemented: Read as `0' bit 0 SWDTEN: Software Controlled Watchdog Timer Enable bit(1) 1 = Watchdog Timer is on 0 = Watchdog Timer is off Note 1: This bit has no effect if the Configuration bit, WDTEN, is enabled. TABLE 23-2: Name RCON WDTCON x = Bit is unknown SUMMARY OF WATCHDOG TIMER REGISTERS Bit 0 Reset Values on page POR BOR 48 -- SWDTEN(2) 50 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 IPEN SBOREN(1) -- RI TO PD -- -- -- -- -- -- Legend: -- = unimplemented, read as `0'. Shaded cells are not used by the Watchdog Timer. Note 1: The SBOREN bit is only available when the BOREN<1:0> Configuration bits = 01; otherwise, it is disabled and reads as `0'. See Section 4.4 "Brown-out Reset (BOR)". 2: This bit has no effect if the Configuration bit, WDTEN, is enabled. (c) 2008 Microchip Technology Inc. DS39631E-page 259 PIC18F2420/2520/4420/4520 23.3 In all other power-managed modes, Two-Speed Startup is not used. The device will be clocked by the currently selected clock source until the primary clock source becomes available. The setting of the IESO bit is ignored. Two-Speed Start-up The Two-Speed Start-up feature helps to minimize the latency period from oscillator start-up to code execution by allowing the microcontroller to use the INTOSC oscillator as a clock source until the primary clock source is available. It is enabled by setting the IESO Configuration bit. 23.3.1 Two-Speed Start-up should be enabled only if the primary oscillator mode is LP, XT, HS or HSPLL (Crystal-Based modes). Other sources do not require an OST start-up delay; for these, Two-Speed Start-up should be disabled. While using the INTOSC oscillator in Two-Speed Startup, the device still obeys the normal command sequences for entering power-managed modes, including multiple SLEEP instructions (refer to Section 3.1.4 "Multiple Sleep Commands"). In practice, this means that user code can change the SCS<1:0> bit settings or issue SLEEP instructions before the OST times out. This would allow an application to briefly wake-up, perform routine "housekeeping" tasks and return to Sleep before the device starts to operate from the primary oscillator. When enabled, Resets and wake-ups from Sleep mode cause the device to configure itself to run from the internal oscillator block as the clock source, following the time-out of the Power-up Timer after a Power-on Reset is enabled. This allows almost immediate code execution while the primary oscillator starts and the OST is running. Once the OST times out, the device automatically switches to PRI_RUN mode. User code can also check if the primary clock source is currently providing the device clocking by checking the status of the OSTS bit (OSCCON<3>). If the bit is set, the primary oscillator is providing the clock. Otherwise, the internal oscillator block is providing the clock during wake-up from Reset or Sleep mode. To use a higher clock speed on wake-up, the INTOSC or postscaler clock sources can be selected to provide a higher clock speed by setting bits, IRCF<2:0>, immediately after Reset. For wake-ups from Sleep, the INTOSC or postscaler clock sources can be selected by setting the IRCF<2:0> bits prior to entering Sleep mode. FIGURE 23-2: SPECIAL CONSIDERATIONS FOR USING TWO-SPEED START-UP TIMING TRANSITION FOR TWO-SPEED START-UP (INTOSC TO HSPLL) Q1 Q3 Q2 Q4 Q2 Q3 Q4 Q1 Q2 Q3 Q1 INTOSC Multiplexer OSC1 TOST(1) TPLL(1) 1 PLL Clock Output 2 n-1 n Clock Transition(2) CPU Clock Peripheral Clock Program Counter PC Wake from Interrupt Event Note 1: 2: DS39631E-page 260 PC + 2 PC + 6 PC + 4 OSTS bit Set TOST = 1024 TOSC; TPLL = 2 ms (approx). These intervals are not shown to scale. Clock transition typically occurs within 2-4 TOSC. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 23.4 Fail-Safe Clock Monitor The Fail-Safe Clock Monitor (FSCM) allows the microcontroller to continue operation in the event of an external oscillator failure by automatically switching the device clock to the internal oscillator block. The FSCM function is enabled by setting the FCMEN Configuration bit. When FSCM is enabled, the INTRC oscillator runs at all times to monitor clocks to peripherals and provide a backup clock in the event of a clock failure. Clock monitoring (shown in Figure 23-3) is accomplished by creating a sample clock signal, which is the INTRC output divided by 64. This allows ample time between FSCM sample clocks for a peripheral clock edge to occur. The peripheral device clock and the sample clock are presented as inputs to the Clock Monitor latch (CM). The CM is set on the falling edge of the device clock source, but cleared on the rising edge of the sample clock. FIGURE 23-3: FSCM BLOCK DIAGRAM Clock Monitor Latch (CM) (edge-triggered) Peripheral Clock INTRC Source / 64 (32 s) 488 Hz (2.048 ms) S Q C Q Clock Failure Detected Clock failure is tested for on the falling edge of the sample clock. If a sample clock falling edge occurs while CM is still set, a clock failure has been detected (Figure 23-4). This causes the following: * the FSCM generates an oscillator fail interrupt by setting bit, OSCFIF (PIR2<7>); * the device clock source is switched to the internal oscillator block (OSCCON is not updated to show the current clock source - this is the fail-safe condition) and * the WDT is reset. During switchover, the postscaler frequency from the internal oscillator block may not be sufficiently stable for timing sensitive applications. In these cases, it may be desirable to select another clock configuration and enter an alternate power-managed mode. This can be done to (c) 2008 Microchip Technology Inc. attempt a partial recovery or execute a controlled shutdown. See Section 3.1.4 "Multiple Sleep Commands" and Section 23.3.1 "Special Considerations for Using Two-Speed Start-up" for more details. To use a higher clock speed on wake-up, the INTOSC or postscaler clock sources can be selected to provide a higher clock speed by setting bits, IRCF<2:0>, immediately after Reset. For wake-ups from Sleep, the INTOSC or postscaler clock sources can be selected by setting the IRCF<2:0> bits prior to entering Sleep mode. The FSCM will detect failures of the primary or secondary clock sources only. If the internal oscillator block fails, no failure would be detected, nor would any action be possible. 23.4.1 FSCM AND THE WATCHDOG TIMER Both the FSCM and the WDT are clocked by the INTRC oscillator. Since the WDT operates with a separate divider and counter, disabling the WDT has no effect on the operation of the INTRC oscillator when the FSCM is enabled. As already noted, the clock source is switched to the INTOSC clock when a clock failure is detected. Depending on the frequency selected by the IRCF<2:0> bits, this may mean a substantial change in the speed of code execution. If the WDT is enabled with a small prescale value, a decrease in clock speed allows a WDT time-out to occur and a subsequent device Reset. For this reason, fail-safe clock events also reset the WDT and postscaler, allowing it to start timing from when execution speed was changed and decreasing the likelihood of an erroneous time-out. 23.4.2 EXITING FAIL-SAFE OPERATION The fail-safe condition is terminated by either a device Reset or by entering a power-managed mode. On Reset, the controller starts the primary clock source specified in Configuration Register 1H (with any required start-up delays that are required for the oscillator mode, such as the OST or PLL timer). The INTOSC multiplexer provides the device clock until the primary clock source becomes ready (similar to a TwoSpeed Start-up). The clock source is then switched to the primary clock (indicated by the OSTS bit in the OSCCON register becoming set). The Fail-Safe Clock Monitor then resumes monitoring the peripheral clock. The primary clock source may never become ready during start-up. In this case, operation is clocked by the INTOSC multiplexer. The OSCCON register will remain in its Reset state until a power-managed mode is entered. DS39631E-page 261 PIC18F2420/2520/4420/4520 FIGURE 23-4: FSCM TIMING DIAGRAM Sample Clock Oscillator Failure Device Clock Output CM Output (Q) Failure Detected OSCFIF CM Test Note: 23.4.3 FSCM INTERRUPTS IN POWER-MANAGED MODES By entering a power-managed mode, the clock multiplexer selects the clock source selected by the OSCCON register. Fail-Safe Clock Monitoring of the powermanaged clock source resumes in the power-managed mode. If an oscillator failure occurs during power-managed operation, the subsequent events depend on whether or not the oscillator failure interrupt is enabled. If enabled (OSCFIF = 1), code execution will be clocked by the INTOSC multiplexer. An automatic transition back to the failed clock source will not occur. If the interrupt is disabled, subsequent interrupts while in Idle mode will cause the CPU to begin executing instructions while being clocked by the INTOSC source. 23.4.4 CM Test CM Test The device clock is normally at a much higher frequency than the sample clock. The relative frequencies in this example have been chosen for clarity. POR OR WAKE FROM SLEEP The FSCM is designed to detect oscillator failure at any point after the device has exited Power-on Reset (POR) or low-power Sleep mode. When the primary device clock is EC, RC or INTRC modes, monitoring can begin immediately following these events. time considerably longer than the FCSM sample clock time, a false clock failure may be detected. To prevent this, the internal oscillator block is automatically configured as the device clock and functions until the primary clock is stable (the OST and PLL timers have timed out). This is identical to Two-Speed Start-up mode. Once the primary clock is stable, the INTRC returns to its role as the FSCM source. Note: The same logic that prevents false oscillator failure interrupts on POR, or wake from Sleep, will also prevent the detection of the oscillator's failure to start at all following these events. This can be avoided by monitoring the OSTS bit and using a timing routine to determine if the oscillator is taking too long to start. Even so, no oscillator failure interrupt will be flagged. As noted in Section 23.3.1 "Special Considerations for Using Two-Speed Start-up", it is also possible to select another clock configuration and enter an alternate power-managed mode while waiting for the primary clock to become stable. When the new powermanaged mode is selected, the primary clock is disabled. For oscillator modes involving a crystal or resonator (HS, HSPLL, LP or XT), the situation is somewhat different. Since the oscillator may require a start-up DS39631E-page 262 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 23.5 Each of the five blocks has three code protection bits associated with them. They are: Program Verification and Code Protection The overall structure of the code protection on the PIC18 Flash devices differs significantly from other PIC(R) devices. * Code-Protect bit (CPn) * Write-Protect bit (WRTn) * External Block Table Read bit (EBTRn) The user program memory is divided into five blocks. One of these is a boot block of 2 Kbytes. The remainder of the memory is divided into four blocks on binary boundaries. Figure 23-5 shows the program memory organization for 16 and 32-Kbyte devices and the specific code protection bit associated with each block. The actual locations of the bits are summarized in Table 23-3. FIGURE 23-5: CODE-PROTECTED PROGRAM MEMORY FOR PIC18F2420/2520/4420/4520 MEMORY SIZE/DEVICE Block Code Protection Controlled By: 16 Kbytes 32 Kbytes Address (PIC18F2420/4420) (PIC18F2520/4520) Range Boot Block Boot Block Block 0 Block 0 000000h 0007FFh CPB, WRTB, EBTRB 000800h CP0, WRT0, EBTR0 001FFFh 002000h Block 1 Block 1 CP1, WRT1, EBTR1 003FFFh 004000h CP2, WRT2, EBTR2 Block 2 005FFFh 006000h Block 3 CP3, WRT3, EBTR3 007FFFh Unimplemented Read `0's Unimplemented Read `0's (Unimplemented Memory Space) 1FFFFFh TABLE 23-3: SUMMARY OF CODE PROTECTION REGISTERS File Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 CP3(1) CP2(1) CP1 CP0 300008h CONFIG5L -- -- -- -- 300009h CONFIG5H CPD CPB -- -- -- -- -- -- 30000Ah CONFIG6L -- -- -- -- WRT3(1) WRT2(1) WRT1 WRT0 30000Bh CONFIG6H WRTD WRTB WRTC -- -- -- -- -- 30000Ch CONFIG7L -- -- -- -- EBTR3(1) EBTR2(1) EBTR1 EBTR0 30000Dh CONFIG7H -- EBTRB -- -- -- -- -- -- Legend: Shaded cells are unimplemented. Note 1: Unimplemented in PIC18F2420/4420 devices; maintain this bit set. (c) 2008 Microchip Technology Inc. DS39631E-page 263 PIC18F2420/2520/4420/4520 23.5.1 PROGRAM MEMORY CODE PROTECTION The program memory may be read to, or written from, any location using the table read and table write instructions. The Device ID may be read with table reads. The Configuration registers may be read and written with the table read and table write instructions. instruction that executes from a location outside of that block is not allowed to read and will result in reading `0's. Figures 23-6 through 23-8 illustrate table write and table read protection. Note: In normal execution mode, the CPn bits have no direct effect. CPn bits inhibit external reads and writes. A block of user memory may be protected from table writes if the WRTn Configuration bit is `0'. The EBTRn bits control table reads. For a block of user memory with the EBTRn bit set to `0', a table read instruction that executes from within that block is allowed to read. A table read FIGURE 23-6: Code protection bits may only be written to a `0' from a `1' state. It is not possible to write a `1' to a bit in the `0' state. Code protection bits are only set to `1' by a full chip erase or block erase function. The full chip erase and block erase functions can only be initiated via ICSP or an external programmer. TABLE WRITE (WRTn) DISALLOWED Register Values Program Memory Configuration Bit Settings 000000h 0007FFh 000800h TBLPTR = 0008FFh PC = 001FFEh WRTB, EBTRB = 11 WRT0, EBTR0 = 01 TBLWT* 001FFFh 002000h WRT1, EBTR1 = 11 003FFFh 004000h PC = 005FFEh WRT2, EBTR2 = 11 TBLWT* 005FFFh 006000h WRT3, EBTR3 = 11 007FFFh Results: All table writes disabled to Blockn whenever WRTn = 0. DS39631E-page 264 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 23-7: EXTERNAL BLOCK TABLE READ (EBTRn) DISALLOWED Register Values Program Memory Configuration Bit Settings 000000h WRTB, EBTRB = 11 0007FFh 000800h TBLPTR = 0008FFh WRT0, EBTR0 = 10 001FFFh 002000h PC = 003FFEh WRT1, EBTR1 = 11 TBLRD* 003FFFh 004000h WRT2, EBTR2 = 11 005FFFh 006000h WRT3, EBTR3 = 11 007FFFh Results: All table reads from external blocks to Blockn are disabled whenever EBTRn = 0. TABLAT register returns a value of `0'. FIGURE 23-8: EXTERNAL BLOCK TABLE READ (EBTRn) ALLOWED Register Values Program Memory Configuration Bit Settings 000000h 0007FFh 000800h TBLPTR = 0008FFh PC = 001FFEh WRTB, EBTRB = 11 WRT0, EBTR0 = 10 TBLRD* 001FFFh 002000h WRT1, EBTR1 = 11 003FFFh 004000h WRT2, EBTR2 = 11 005FFFh 006000h WRT3, EBTR3 = 11 007FFFh Results: Table reads permitted within Blockn, even when EBTRBn = 0. TABLAT register returns the value of the data at the location TBLPTR. (c) 2008 Microchip Technology Inc. DS39631E-page 265 PIC18F2420/2520/4420/4520 23.5.2 DATA EEPROM CODE PROTECTION The entire data EEPROM is protected from external reads and writes by two bits: CPD and WRTD. CPD inhibits external reads and writes of data EEPROM. WRTD inhibits internal and external writes to data EEPROM. The CPU can always read data EEPROM under normal operation, regardless of the protection bit settings. 23.5.3 CONFIGURATION REGISTER PROTECTION The Configuration registers can be write-protected. The WRTC bit controls protection of the Configuration registers. In normal execution mode, the WRTC bit is read-only. WRTC can only be written via ICSP or an external programmer. 23.6 ID Locations Eight memory locations (200000h-200007h) are designated as ID locations, where the user can store checksum or other code identification numbers. These locations are both readable and writable during normal execution through the TBLRD and TBLWT instructions, or during program/verify. The ID locations can be read when the device is code-protected. 23.7 In-Circuit Serial Programming PIC18F2420/2520/4420/4520 devices can be serially programmed while in the end application circuit. This is simply done with two lines for clock and data and three other lines for power, ground and the programming voltage. This allows customers to manufacture boards with unprogrammed devices and then program the microcontroller just before shipping the product. This also allows the most recent firmware or a custom firmware to be programmed. 23.8 In-Circuit Debugger When the DEBUG Configuration bit is programmed to a `0', the In-Circuit Debugger functionality is enabled. This function allows simple debugging functions when used with MPLAB(R) IDE. When the microcontroller has this feature enabled, some resources are not available for general use. Table 23-4 shows which resources are required by the background debugger. TABLE 23-4: DEBUGGER RESOURCES I/O pins: 23.9 Single-Supply ICSP Programming The LVP Configuration bit enables Single-Supply ICSP Programming (formerly known as Low-Voltage ICSP Programming or LVP). When Single-Supply Programming is enabled, the microcontroller can be programmed without requiring high voltage being applied to the MCLR/VPP/RE3 pin, but the RB5/KBI1/PGM pin is then dedicated to controlling Program mode entry and is not available as a general purpose I/O pin. While programming, using Single-Supply Programming mode, VDD is applied to the MCLR/VPP/RE3 pin as in normal execution mode. To enter Programming mode, VDD is applied to the PGM pin. Note 1: High-voltage programming is always available, regardless of the state of the LVP bit or the PGM pin, by applying VIHH to the MCLR pin. 2: By default, Single-Supply ICSP is enabled in unprogrammed devices (as supplied from Microchip) and erased devices. 3: When Single-Supply Programming is enabled, the RB5 pin can no longer be used as a general purpose I/O pin. 4: When LVP is enabled, externally pull the PGM pin to VSS to allow normal program execution. If Single-Supply ICSP Programming mode will not be used, the LVP bit can be cleared. RB5/KBI1/PGM then becomes available as the digital I/O pin, RB5. The LVP bit may be set or cleared only when using standard high-voltage programming (VIHH applied to the MCLR/ VPP/RE3 pin). Once LVP has been disabled, only the standard high-voltage programming is available and must be used to program the device. Memory that is not code-protected can be erased using either a block erase, or erased row by row, then written at any specified VDD. If code-protected memory is to be erased, a block erase is required. If a block erase is to be performed when using Low-Voltage Programming, the device must be supplied with VDD of 4.5V to 5.5V. RB6, RB7 Stack: 2 levels Program Memory: 512 bytes Data Memory: 10 bytes DS39631E-page 266 To use the In-Circuit Debugger function of the microcontroller, the design must implement In-Circuit Serial Programming connections to MCLR/VPP/RE3, VDD, VSS, RB7 and RB6. This will interface to the In-Circuit Debugger module available from Microchip or one of the third party development tool companies. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 24.0 INSTRUCTION SET SUMMARY PIC18F2420/2520/4420/4520 devices incorporate the standard set of 75 PIC18 core instructions, as well as an extended set of 8 new instructions, for the optimization of code that is recursive or that utilizes a software stack. The extended set is discussed later in this section. 24.1 Standard Instruction Set The standard PIC18 instruction set adds many enhancements to the previous PIC(R) MCU instruction sets, while maintaining an easy migration from these PIC MCU instruction sets. Most instructions are a single program memory word (16 bits), but there are four instructions that require two program memory locations. Each single-word instruction is a 16-bit word divided into an opcode, which specifies the instruction type and one or more operands, which further specify the operation of the instruction. The instruction set is highly orthogonal and is grouped into four basic categories: * * * * Byte-oriented operations Bit-oriented operations Literal operations Control operations The PIC18 instruction set summary in Table 24-2 lists byte-oriented, bit-oriented, literal and control operations. Table 24-1 shows the opcode field descriptions. Most byte-oriented instructions have three operands: 1. 2. 3. The file register (specified by `f') The destination of the result (specified by `d') The accessed memory (specified by `a') The file register designator `f' specifies which file register is to be used by the instruction. The destination designator `d' specifies where the result of the operation is to be placed. If `d' is zero, the result is placed in the WREG register. If `d' is one, the result is placed in the file register specified in the instruction. All bit-oriented instructions have three operands: 1. 2. 3. The file register (specified by `f') The bit in the file register (specified by `b') The accessed memory (specified by `a') The literal instructions may use some of the following operands: * A literal value to be loaded into a file register (specified by `k') * The desired FSR register to load the literal value into (specified by `f') * No operand required (specified by `--') The control instructions may use some of the following operands: * A program memory address (specified by `n') * The mode of the CALL or RETURN instructions (specified by `s') * The mode of the table read and table write instructions (specified by `m') * No operand required (specified by `--') All instructions are a single word, except for four double-word instructions. These instructions were made double-word to contain the required information in 32 bits. In the second word, the 4 MSbs are `1's. If this second word is executed as an instruction (by itself), it will execute as a NOP. All single-word instructions are executed in a single instruction cycle, unless a conditional test is true or the program counter is changed as a result of the instruction. In these cases, the execution takes two instruction cycles, with the additional instruction cycle(s) executed as a NOP. The double-word instructions execute in two instruction cycles. One instruction cycle consists of four oscillator periods. Thus, for an oscillator frequency of 4 MHz, the normal instruction execution time is 1 s. If a conditional test is true, or the program counter is changed as a result of an instruction, the instruction execution time is 2 s. Two-word branch instructions (if true) would take 3 s. Figure 24-1 shows the general formats that the instructions can have. All examples use the convention `nnh' to represent a hexadecimal number. The Instruction Set Summary, shown in Table 24-2, lists the standard instructions recognized by the Microchip Assembler (MPASMTM). Section 24.1.1 "Standard Instruction Set" provides a description of each instruction. The bit field designator `b' selects the number of the bit affected by the operation, while the file register designator `f' represents the number of the file in which the bit is located. (c) 2008 Microchip Technology Inc. DS39631E-page 267 PIC18F2420/2520/4420/4520 TABLE 24-1: OPCODE FIELD DESCRIPTIONS Field Description a RAM access bit a = 0: RAM location in Access RAM (BSR register is ignored) a = 1: RAM bank is specified by BSR register bbb Bit address within an 8-bit file register (0 to 7). BSR Bank Select Register. Used to select the current RAM bank. C, DC, Z, OV, N ALU Status bits: Carry, Digit Carry, Zero, Overflow, Negative. d Destination select bit d = 0: store result in WREG d = 1: store result in file register f dest Destination: either the WREG register or the specified register file location. f 8-bit Register file address (00h to FFh) or 2-bit FSR designator (0h to 3h). fs 12-bit Register file address (000h to FFFh). This is the source address. fd 12-bit Register file address (000h to FFFh). This is the destination address. GIE Global Interrupt Enable bit. k Literal field, constant data or label (may be either an 8-bit, 12-bit or a 20-bit value). label Label name. mm The mode of the TBLPTR register for the table read and table write instructions. Only used with table read and table write instructions: * No change to register (such as TBLPTR with table reads and writes) *+ Post-Increment register (such as TBLPTR with table reads and writes) *- Post-Decrement register (such as TBLPTR with table reads and writes) Pre-Increment register (such as TBLPTR with table reads and writes) +* n The relative address (2's complement number) for relative branch instructions or the direct address for Call/Branch and Return instructions. PC Program Counter. PCL Program Counter Low Byte. PCH Program Counter High Byte. PCLATH Program Counter High Byte Latch. PCLATU Program Counter Upper Byte Latch. PD Power-down bit. PRODH Product of Multiply High Byte. PRODL Product of Multiply Low Byte. s Fast Call/Return mode select bit s = 0: do not update into/from shadow registers s = 1: certain registers loaded into/from shadow registers (Fast mode) TBLPTR 21-bit Table Pointer (points to a Program Memory location). TABLAT 8-bit Table Latch. TO Time-out bit. TOS Top-of-Stack. u Unused or unchanged. WDT Watchdog Timer. WREG Working register (accumulator). x Don't care (`0' or `1'). The assembler will generate code with x = 0. It is the recommended form of use for compatibility with all Microchip software tools. zs 7-bit offset value for indirect addressing of register files (source). 7-bit offset value for indirect addressing of register files (destination). zd { } Optional argument. [text] Indicates an indexed address. (text) The contents of text. [expr]<n> Specifies bit n of the register indicated by the pointer expr. Assigned to. < > Register bit field. In the set of. italics User-defined term (font is Courier New). DS39631E-page 268 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 24-1: GENERAL FORMAT FOR INSTRUCTIONS Byte-oriented file register operations 15 10 9 OPCODE Example Instruction 8 7 d 0 a f (FILE #) ADDWF MYREG, W, B d = 0 for result destination to be WREG register d = 1 for result destination to be file register (f) a = 0 to force Access Bank a = 1 for BSR to select bank f = 8-bit file register address Byte to Byte move operations (2-word) 15 12 11 0 OPCODE 15 f (Source FILE #) 12 11 MOVFF MYREG1, MYREG2 0 f (Destination FILE #) 1111 f = 12-bit file register address Bit-oriented file register operations 15 12 11 9 8 7 0 OPCODE b (BIT #) a f (FILE #) BSF MYREG, bit, B b = 3-bit position of bit in file register (f) a = 0 to force Access Bank a = 1 for BSR to select bank f = 8-bit file register address Literal operations 15 8 7 0 OPCODE k (literal) MOVLW 7Fh k = 8-bit immediate value Control operations CALL, GOTO and Branch operations 15 8 7 0 OPCODE 15 n<7:0> (literal) 12 11 GOTO Label 0 n<19:8> (literal) 1111 n = 20-bit immediate value 15 8 7 S OPCODE 15 0 n<7:0> (literal) 12 11 CALL MYFUNC 0 n<19:8> (literal) 1111 S = Fast bit 15 11 10 OPCODE 15 0 n<10:0> (literal) 8 7 OPCODE (c) 2008 Microchip Technology Inc. BRA MYFUNC 0 n<7:0> (literal) BC MYFUNC DS39631E-page 269 PIC18F2420/2520/4420/4520 TABLE 24-2: PIC18FXXXX INSTRUCTION SET Mnemonic, Operands 16-Bit Instruction Word Description Cycles MSb LSb Status Affected Notes BYTE-ORIENTED OPERATIONS ADDWF ADDWFC ANDWF CLRF COMF CPFSEQ CPFSGT CPFSLT DECF DECFSZ DCFSNZ INCF INCFSZ INFSNZ IORWF MOVF MOVFF f, d, a f, d, a f, d, a f, a f, d, a f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a f, d, a fs, fd MOVWF MULWF NEGF RLCF RLNCF RRCF RRNCF SETF SUBFWB f, a f, a f, a f, d, a f, d, a f, d, a f, d, a f, a f, d, a SUBWF SUBWFB f, d, a f, d, a SWAPF TSTFSZ XORWF f, d, a f, a f, d, a Note 1: When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. 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. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction. 2: 3: 4: DS39631E-page 270 Add WREG and f Add WREG and Carry bit to f AND WREG with f Clear f Complement f Compare f with WREG, Skip = Compare f with WREG, Skip > Compare f with WREG, Skip < Decrement f Decrement f, Skip if 0 Decrement f, Skip if Not 0 Increment f Increment f, Skip if 0 Increment f, Skip if Not 0 Inclusive OR WREG with f Move f Move fs (source) to 1st word fd (destination) 2nd word Move WREG to f Multiply WREG with f Negate f Rotate Left f through Carry Rotate Left f (No Carry) Rotate Right f through Carry Rotate Right f (No Carry) Set f Subtract f from WREG with Borrow Subtract WREG from f Subtract WREG from f with Borrow Swap Nibbles in f Test f, Skip if 0 Exclusive OR WREG with f 1 1 1 1 1 1 (2 or 3) 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 (2 or 3) 1 (2 or 3) 1 1 2 C, DC, Z, OV, N C, DC, Z, OV, N Z, N Z Z, N None None None C, DC, Z, OV, N None None C, DC, Z, OV, N None None Z, N Z, N None 1, 2 1, 2 1,2 2 1, 2 4 4 1, 2 1, 2, 3, 4 1, 2, 3, 4 1, 2 1, 2, 3, 4 4 1, 2 1, 2 1 1 1 1 1 1 1 1 1 1 0010 0010 0001 0110 0001 0110 0110 0110 0000 0010 0100 0010 0011 0100 0001 0101 1100 1111 0110 0000 0110 0011 0100 0011 0100 0110 0101 01da 00da 01da 101a 11da 001a 010a 000a 01da 11da 11da 10da 11da 10da 00da 00da ffff ffff 111a 001a 110a 01da 01da 00da 00da 100a 01da ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff 1 1 0101 0101 11da 10da ffff ffff ffff C, DC, Z, OV, N ffff C, DC, Z, OV, N 1, 2 1 1 (2 or 3) 1 0011 0110 0001 10da 011a 10da ffff ffff ffff ffff None ffff None ffff Z, N 4 1, 2 None None C, DC, Z, OV, N C, Z, N Z, N C, Z, N Z, N None C, DC, Z, OV, N 1, 2 1, 2 1, 2 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 24-2: PIC18FXXXX INSTRUCTION SET (CONTINUED) 16-Bit Instruction Word Mnemonic, Operands Description Cycles MSb LSb Status Affected Notes BIT-ORIENTED OPERATIONS BCF BSF BTFSC BTFSS BTG f, b, a f, b, a f, b, a f, b, a f, d, a Bit Clear f Bit Set f Bit Test f, Skip if Clear Bit Test f, Skip if Set Bit Toggle f 1 1 1 (2 or 3) 1 (2 or 3) 1 1001 1000 1011 1010 0111 bbba bbba bbba bbba bbba ffff ffff ffff ffff ffff ffff ffff ffff ffff ffff None None None None None 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 1 (2) 2 1 (2) 2 0010 0110 0011 0111 0101 0001 0100 0nnn 0000 110s kkkk 0000 0000 1111 kkkk 0000 xxxx 0000 0000 1nnn 0000 0000 nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0000 0000 kkkk kkkk 0000 xxxx 0000 0000 nnnn 1111 0001 nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn nnnn kkkk kkkk 0100 0111 kkkk kkkk 0000 xxxx 0110 0101 nnnn 1111 000s None None None None None None None None None None 1 1 1 1 2 1 2 1110 1110 1110 1110 1110 1110 1110 1101 1110 1110 1111 0000 0000 1110 1111 0000 1111 0000 0000 1101 0000 0000 2 2 1 0000 0000 0000 1100 0000 0000 kkkk 0001 0000 1, 2 1, 2 3, 4 3, 4 1, 2 CONTROL OPERATIONS BC BN BNC BNN BNOV BNZ BOV BRA BZ CALL n n n n n n n n n n, s CLRWDT DAW GOTO -- -- n NOP NOP POP PUSH RCALL RESET RETFIE -- -- -- -- n s Branch if Carry Branch if Negative Branch if Not Carry Branch if Not Negative Branch if Not Overflow Branch if Not Zero Branch if Overflow Branch Unconditionally Branch if Zero Call Subroutine 1st word 2nd word Clear Watchdog Timer Decimal Adjust WREG Go to Address 1st word 2nd word No Operation No Operation Pop Top of Return Stack (TOS) Push Top of Return Stack (TOS) Relative Call Software Device Reset Return from Interrupt Enable RETLW RETURN SLEEP k s -- Return with Literal in WREG Return from Subroutine Go into Standby mode Note 1: When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. 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. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction. 2: 3: 4: (c) 2008 Microchip Technology Inc. 1 1 2 TO, PD C None None None None None None All GIE/GIEH, PEIE/GIEL kkkk None 001s None 0011 TO, PD 4 DS39631E-page 271 PIC18F2420/2520/4420/4520 TABLE 24-2: PIC18FXXXX INSTRUCTION SET (CONTINUED) 16-Bit Instruction Word Mnemonic, Operands Description Cycles MSb LSb Status Affected Notes LITERAL OPERATIONS ADDLW ANDLW IORLW LFSR k k k f, k MOVLB MOVLW MULLW RETLW SUBLW XORLW k k k k k k Add Literal and WREG AND Literal with WREG Inclusive OR Literal with WREG Move Literal (12-bit) 2nd word to FSR(f) 1st word Move Literal to BSR<3:0> Move Literal to WREG Multiply Literal with WREG Return with Literal in WREG Subtract WREG from Literal Exclusive OR Literal with WREG 1 1 1 2 1 1 1 2 1 1 0000 0000 0000 1110 1111 0000 0000 0000 0000 0000 0000 1111 1011 1001 1110 0000 0001 1110 1101 1100 1000 1010 kkkk kkkk kkkk 00ff kkkk 0000 kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk kkkk C, DC, Z, OV, N Z, N Z, N None 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 1000 1001 1010 1011 1100 1101 1110 1111 None None None None None None None None None None None None C, DC, Z, OV, N Z, N DATA MEMORY PROGRAM MEMORY OPERATIONS TBLRD* TBLRD*+ TBLRD*TBLRD+* TBLWT* TBLWT*+ TBLWT*TBLWT+* Note 1: 2: 3: 4: Table Read Table Read with Post-Increment Table Read with Post-Decrement Table Read with Pre-Increment Table Write Table Write with Post-Increment Table Write with Post-Decrement Table Write with Pre-Increment 2 2 When a PORT register is modified as a function of itself (e.g., MOVF PORTB, 1, 0), the value used will be that value present on the pins themselves. For example, if the data latch is `1' for a pin configured as input and is driven low by an external device, the data will be written back with a `0'. If this instruction is executed on the TMR0 register (and where applicable, `d' = 1), the prescaler will be cleared if assigned. 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. Some instructions are two-word instructions. The second word of these instructions will be executed as a NOP unless the first word of the instruction retrieves the information embedded in these 16 bits. This ensures that all program memory locations have a valid instruction. DS39631E-page 272 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 24.1.1 STANDARD INSTRUCTION SET ADDLW ADD Literal to W ADDWF ADD W to f Syntax: ADDLW Syntax: ADDWF Operands: 0 f 255 d [0,1] a [0,1] Operation: (W) + (f) dest Status Affected: N, OV, C, DC, Z k Operands: 0 k 255 Operation: (W) + k W Status Affected: N, OV, C, DC, Z Encoding: 0000 1111 kkkk kkkk Description: The contents of W are added to the 8-bit literal `k' and the result is placed in W. Words: 1 Cycles: 1 Encoding: 0010 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write to W Example: ADDLW = 25h ffff Words: 1 Cycles: 1 Before Instruction W ffff Add W to register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 15h W = 10h After Instruction 01da Description: Q Cycle Activity: Decode f {,d {,a}} Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: ADDWF REG, 0, 0 Before Instruction W = REG = After Instruction W REG Note: = = 17h 0C2h 0D9h 0C2h All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in symbolic addressing. If a label is used, the instruction format then becomes: {label} instruction argument(s). (c) 2008 Microchip Technology Inc. DS39631E-page 273 PIC18F2420/2520/4420/4520 ADDWFC ADD W and Carry bit to f ANDLW AND Literal with W Syntax: ADDWFC Syntax: ANDLW Operands: 0 f 255 d [0,1] a [0,1] f {,d {,a}} Operation: (W) + (f) + (C) dest Status Affected: N,OV, C, DC, Z Encoding: 0010 Description: 00da ffff Add W, the Carry flag and data memory location `f'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed in data memory location `f'. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Operands: 0 k 255 Operation: (W) .AND. k W Status Affected: N, Z Encoding: ffff k 0000 1011 kkkk kkkk Description: The contents of W are ANDed with the 8-bit literal `k'. The result is placed in W. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read literal `k' Process Data Write to W Example: ANDLW 05Fh Before Instruction W = After Instruction W = A3h 03h Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: ADDWFC Before Instruction Carry bit = REG = W = After Instruction Carry bit = REG = W = DS39631E-page 274 REG, 0, 1 1 02h 4Dh 0 02h 50h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 ANDWF AND W with f BC Branch if Carry Syntax: ANDWF Syntax: BC Operands: 0 f 255 d [0,1] a [0,1] Operands: -128 n 127 Operation: if Carry bit is `1', (PC) + 2 + 2n PC Status Affected: None f {,d {,a}} Operation: (W) .AND. (f) dest Status Affected: N, Z Encoding: 0001 Description: Encoding: 01da ffff ffff The contents of W are ANDed with register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: ANDWF REG, 0, 0 Before Instruction W = REG = After Instruction W REG = = 17h C2h 02h C2h (c) 2008 Microchip Technology Inc. n 1110 Description: 0010 nnnn nnnn If the Carry bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Cycles: 1(2) Q Cycle Activity: If Jump: Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data Write to PC No operation No operation No operation No operation If No Jump: Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation Example: HERE Before Instruction PC After Instruction If Carry PC If Carry PC BC 5 = address (HERE) = = = = 1; address (HERE + 12) 0; address (HERE + 2) DS39631E-page 275 PIC18F2420/2520/4420/4520 BCF Bit Clear f BN Branch if Negative Syntax: BCF Syntax: BN Operands: 0 f 255 0b7 a [0,1] Operands: -128 n 127 Operation: if Negative bit is `1', (PC) + 2 + 2n PC Status Affected: None f, b {,a} Operation: 0 f<b> Status Affected: None Encoding: Encoding: 1001 Description: bbba ffff ffff Bit `b' in register `f' is cleared. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: BCF Before Instruction FLAG_REG = After Instruction FLAG_REG = DS39631E-page 276 FLAG_REG, 7, 0 n 1110 Description: 0110 nnnn nnnn If the Negative bit is `1', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Cycles: 1(2) Q Cycle Activity: If Jump: Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data Write to PC No operation No operation No operation No operation If No Jump: Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation C7h 47h Example: HERE Before Instruction PC After Instruction If Negative PC If Negative PC BN Jump = address (HERE) = = = = 1; address (Jump) 0; address (HERE + 2) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 BNC Branch if Not Carry BNN Branch if Not Negative Syntax: BNC Syntax: BNN n n Operands: -128 n 127 Operands: -128 n 127 Operation: if Carry bit is `0', (PC) + 2 + 2n PC Operation: if Negative bit is `0', (PC) + 2 + 2n PC Status Affected: None Status Affected: None Encoding: 1110 0011 nnnn nnnn Encoding: 1110 0111 nnnn nnnn Description: If the Carry bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Description: If the Negative bit is `0', then the program will branch. The 2's complement number `2n' is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Words: 1 Cycles: 1(2) Cycles: 1(2) Q Cycle Activity: If Jump: Q Cycle Activity: If Jump: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data Write to PC Decode Read literal `n' Process Data Write to PC No operation No operation No operation No operation No operation No operation No operation No operation Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation Decode Read literal `n' Process Data No operation If No Jump: Example: If No Jump: HERE Before Instruction PC After Instruction If Carry PC If Carry PC BNC Jump = address (HERE) = = = = 0; address (Jump) 1; address (HERE + 2) (c) 2008 Microchip Technology Inc. Example: HERE Before Instruction PC After Instruction If Negative PC If Negative PC BNN Jump = address (HERE) = = = = 0; address (Jump) 1; address (HERE + 2) DS39631E-page 277 PIC18F2420/2520/4420/4520 BNOV Branch if Not Overflow BNZ Branch if Not Zero Syntax: BNOV Syntax: BNZ n n Operands: -128 n 127 Operands: -128 n 127 Operation: if Overflow bit is `0', (PC) + 2 + 2n PC Operation: if Zero bit is `0', (PC) + 2 + 2n PC Status Affected: None Status Affected: None Encoding: 1110 0101 nnnn nnnn Encoding: 1110 0001 nnnn nnnn Description: If the Overflow bit is `0', then the program will branch. The 2's complement number, `2n', is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Description: If the Zero bit is `0', then the program will branch. The 2's complement number, `2n', is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Words: 1 Cycles: 1(2) Cycles: 1(2) Q Cycle Activity: If Jump: Q Cycle Activity: If Jump: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data Write to PC Decode Read literal `n' Process Data Write to PC No operation No operation No operation No operation No operation No operation No operation No operation Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation Decode Read literal `n' Process Data No operation If No Jump: If No Jump: Example: HERE Before Instruction PC After Instruction If Overflow PC If Overflow PC DS39631E-page 278 BNOV Jump = address (HERE) = = = = 0; address (Jump) 1; address (HERE + 2) Example: HERE Before Instruction PC After Instruction If Zero PC If Zero PC BNZ Jump = address (HERE) = = = = 0; address (Jump) 1; address (HERE + 2) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 BRA Unconditional Branch BSF Bit Set f Syntax: BRA Syntax: BSF Operands: 0 f 255 0b7 a [0,1] Operation: 1 f<b> Status Affected: None n Operands: -1024 n 1023 Operation: (PC) + 2 + 2n PC Status Affected: None Encoding: 1101 Description: 0nnn nnnn nnnn Add the 2's complement number, `2n', to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is a two-cycle instruction. Words: 1 Cycles: 2 Encoding: 1000 Q1 Q2 Q3 Q4 Read literal `n' Process Data Write to PC No operation No operation No operation No operation Example: bbba ffff ffff Description: Bit `b' in register `f' is set. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Decode f, b {,a} Q Cycle Activity: HERE Before Instruction PC After Instruction PC BRA Jump = address (HERE) = address (Jump) Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: BSF Before Instruction FLAG_REG After Instruction FLAG_REG (c) 2008 Microchip Technology Inc. FLAG_REG, 7, 1 = 0Ah = 8Ah DS39631E-page 279 PIC18F2420/2520/4420/4520 BTFSC Bit Test File, Skip if Clear BTFSS Bit Test File, Skip if Set Syntax: BTFSC f, b {,a} Syntax: BTFSS f, b {,a} Operands: 0 f 255 0b7 a [0,1] Operands: 0 f 255 0b<7 a [0,1] Operation: skip if (f<b>) = 0 Operation: skip if (f<b>) = 1 Status Affected: None Status Affected: None Encoding: 1011 Description: bbba ffff ffff Encoding: 1010 If bit `b' in register `f' is `0', then the next instruction is skipped. If bit `b' is `0', then the next instruction fetched during the current instruction execution is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Description: Words: 1 Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Cycles: 1(2) Note: Q Cycle Activity: bbba ffff ffff If bit `b' in register `f' is `1', then the next instruction is skipped. If bit `b' is `1', then the next instruction fetched during the current instruction execution is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 3 cycles if skip and followed by a 2-word instruction. Q Cycle Activity: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data No operation Decode Read register `f' Process Data No operation Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation If skip: If skip: If skip and followed by 2-word instruction: If skip and followed by 2-word instruction: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation Example: HERE FALSE TRUE Before Instruction PC After Instruction If FLAG<1> PC If FLAG<1> PC DS39631E-page 280 BTFSC : : FLAG, 1, 0 = address (HERE) = = = = 0; address (TRUE) 1; address (FALSE) Example: HERE FALSE TRUE Before Instruction PC After Instruction If FLAG<1> PC If FLAG<1> PC BTFSS : : FLAG, 1, 0 = address (HERE) = = = = 0; address (FALSE) 1; address (TRUE) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 BTG Bit Toggle f BOV Branch if Overflow Syntax: BTG f, b {,a} Syntax: BOV Operands: 0 f 255 0b<7 a [0,1] Operands: -128 n 127 Operation: if Overflow bit is `1', (PC) + 2 + 2n PC Status Affected: None Operation: (f<b>) f<b> Status Affected: None Encoding: 0111 Description: Encoding: bbba ffff ffff Bit `b' in data memory location `f' is inverted. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. n 1110 0100 nnnn nnnn Description: If the Overflow bit is `1', then the program will branch. The 2's complement number, `2n', is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Cycles: 1(2) Q Cycle Activity: If Jump: Words: 1 Q1 Q2 Q3 Q4 Cycles: 1 Decode Read literal `n' Process Data Write to PC No operation No operation No operation No operation Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: BTG PORTC, Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation 4, 0 Before Instruction: PORTC = 0111 0101 [75h] After Instruction: PORTC = 0110 0101 [65h] (c) 2008 Microchip Technology Inc. If No Jump: Example: HERE Before Instruction PC After Instruction If Overflow PC If Overflow PC BOV Jump = address (HERE) = = = = 1; address (Jump) 0; address (HERE + 2) DS39631E-page 281 PIC18F2420/2520/4420/4520 BZ Branch if Zero CALL Subroutine Call Syntax: BZ Syntax: CALL k {,s} n Operands: -128 n 127 Operands: Operation: if Zero bit is `1', (PC) + 2 + 2n PC 0 k 1048575 s [0,1] Operation: Status Affected: None (PC) + 4 TOS, k PC<20:1>; if s = 1, (W) WS, (STATUS) STATUSS, (BSR) BSRS Status Affected: None Encoding: 1110 Description: 0000 nnnn nnnn If the Zero bit is `1', then the program will branch. The 2's complement number, `2n', is added to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is then a two-cycle instruction. Words: 1 Cycles: 1(2) Encoding: 1st word (k<7:0>) 2nd word(k<19:8>) Q1 Q2 Q3 Q4 Read literal `n' Process Data Write to PC No operation No operation No operation No operation If No Jump: Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data No operation Example: HERE Before Instruction PC After Instruction If Zero PC If Zero PC DS39631E-page 282 BZ k7kkk kkkk 110s k19kkk Subroutine call of entire 2-Mbyte memory range. First, return address (PC + 4) is pushed onto the return stack. If `s' = 1, the W, STATUS and BSR registers are also pushed into their respective shadow registers, WS, STATUSS and BSRS. If `s' = 0, no update occurs (default). Then, the 20-bit value `k' is loaded into PC<20:1>. CALL is a two-cycle instruction. Words: 2 Cycles: 2 Q Cycle Activity: Q1 Decode Q2 Q3 Q4 Read literal PUSH PC to `k'<7:0>, stack Jump = address (HERE) = = = = 1; address (Jump) 0; address (HERE + 2) kkkk0 kkkk8 Description: Q Cycle Activity: If Jump: Decode 1110 1111 No operation Example: No operation HERE Before Instruction PC = After Instruction PC = TOS = WS = BSRS = STATUSS = No operation CALL Read literal `k'<19:8>, Write to PC No operation THERE, 1 address (HERE) address (THERE) address (HERE + 4) W BSR STATUS (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 CLRF Clear f Syntax: CLRF Operands: 0 f 255 a [0,1] f {,a} Operation: 000h f, 1Z Status Affected: Z Encoding: 0110 Description: 101a ffff ffff Clears the contents of the specified register. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' CLRF Before Instruction FLAG_REG After Instruction FLAG_REG Clear Watchdog Timer Syntax: CLRWDT Operands: None Operation: 000h WDT, 000h WDT postscaler, 1 TO, 1 PD Status Affected: TO, PD Encoding: FLAG_REG, 1 = 5Ah = 00h (c) 2008 Microchip Technology Inc. 0000 Description: 0000 0000 0100 CLRWDT instruction resets the Watchdog Timer. It also resets the postscaler of the WDT. Status bits, TO and PD, are set. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode No operation Process Data No operation Example: Q Cycle Activity: Example: CLRWDT CLRWDT Before Instruction WDT Counter After Instruction WDT Counter WDT Postscaler TO PD = ? = = = = 00h 0 1 1 DS39631E-page 283 PIC18F2420/2520/4420/4520 COMF Complement f CPFSEQ Compare f with W, Skip if f = W Syntax: COMF Syntax: CPFSEQ Operands: 0 f 255 a [0,1] Operation: (f) - (W), skip if (f) = (W) (unsigned comparison) Status Affected: None f {,d {,a}} 0 f 255 d [0,1] a [0,1] Operands: Operation: (f) dest Status Affected: N, Z Encoding: 0001 11da ffff ffff 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 register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Encoding: 0110 f {,a} 001a ffff ffff Description: Compares the contents of data memory location `f' to the contents of W by performing an unsigned subtraction. If `f' = W, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q Cycle Activity: Example: COMF Before Instruction REG = After Instruction REG = W = Q1 Q2 Q3 Q4 Decode Read register `f' Process Data No operation REG, 0, 0 13h If skip: 13h ECh Q1 Q2 Q3 No No No operation operation operation If skip and followed by 2-word instruction: Q1 Q2 Q3 No No No operation operation operation No No No operation operation operation Example: DS39631E-page 284 HERE NEQUAL EQUAL Q4 No operation Q4 No operation No operation CPFSEQ REG, 0 : : Before Instruction PC Address W REG After Instruction = = = HERE ? ? If REG PC If REG PC = = = W; Address (EQUAL) W; Address (NEQUAL) (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 CPFSGT Compare f with W, Skip if f > W CPFSLT Compare f with W, Skip if f < W Syntax: CPFSGT Syntax: CPFSLT Operands: 0 f 255 a [0,1] Operands: 0 f 255 a [0,1] Operation: (f) - (W), skip if (f) > (W) (unsigned comparison) Operation: (f) - (W), skip if (f) < (W) (unsigned comparison) Status Affected: None Status Affected: None Encoding: 0110 Description: Words: f {,a} 010a ffff ffff Compares the contents of data memory location `f' to the contents of the W by performing an unsigned subtraction. If the contents of `f' are greater than the contents of WREG, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Encoding: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q2 Read register `f' Q3 Process Data Q4 No operation Q1 Q2 Q3 No No No operation operation operation If skip and followed by 2-word instruction: Q1 Q2 Q3 No No No operation operation operation No No No operation operation operation Q4 No operation Example: HERE NGREATER GREATER CPFSGT REG, 0 : : Before Instruction PC W After Instruction = = Address (HERE) ? If REG PC If REG PC > = = W; Address (GREATER) W; Address (NGREATER) (c) 2008 Microchip Technology Inc. ffff ffff Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data No operation Q1 Q2 Q3 Q4 No operation No operation No operation No operation If skip: If skip and followed by 2-word instruction: If skip: Q4 No operation No operation 000a Compares the contents of data memory location `f' to the contents of W by performing an unsigned subtraction. If the contents of `f' are less than the contents of W, then the fetched instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). Q Cycle Activity: Q1 Decode 0110 Description: 1 Cycles: f {,a} Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation Example: HERE NLESS LESS CPFSLT REG, 1 : : Before Instruction PC W After Instruction = = Address (HERE) ? If REG PC If REG PC < = = W; Address (LESS) W; Address (NLESS) DS39631E-page 285 PIC18F2420/2520/4420/4520 DAW Decimal Adjust W Register DECF Decrement f Syntax: DAW Syntax: DECF f {,d {,a}} Operands: None Operands: Operation: If [W<3:0> > 9] or [DC = 1] then, (W<3:0>) + 6 W<3:0>; else, (W<3:0>) W<3:0>; 0 f 255 d [0,1] a [0,1] Operation: (f) - 1 dest Status Affected: C, DC, N, OV, Z If [W<7:4> + DC > 9] or [C = 1] then, (W<7:4>) + 6 + DC W<7:4>; else, (W<7:4>) + DC W<7:4> Status Affected: Encoding: 0000 0000 0000 DAW adjusts the 8-bit value in W, resulting from the earlier addition of two variables (each in packed BCD format) and produces a correct packed BCD result. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register W Process Data Write W Example 1: DAW = = = A5h 0 0 05h 1 0 ffff Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Before Instruction W = C = DC = After Instruction ffff Decrement register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 0111 Description: 01da Description: C Encoding: W C DC Example 2: 0000 Example: DECF Before Instruction CNT = Z = After Instruction CNT = Z = CNT, 1, 0 01h 0 00h 1 Before Instruction W = C = DC = After Instruction W C DC = = = DS39631E-page 286 CEh 0 0 34h 1 0 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 DECFSZ Decrement f, Skip if 0 DCFSNZ Decrement f, Skip if Not 0 Syntax: DECFSZ f {,d {,a}} Syntax: DCFSNZ Operands: 0 f 255 d [0,1] a [0,1] Operands: 0 f 255 d [0,1] a [0,1] Operation: (f) - 1 dest, skip if result = 0 Operation: (f) - 1 dest, skip if result 0 Status Affected: None Status Affected: None Encoding: 0010 11da ffff ffff Description: The contents of register `f' are decremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Encoding: 0100 Description: Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Q1 Q2 Q3 Q4 No operation No operation No operation No operation Words: 1 Cycles: 1(2) Note: Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation HERE DECFSZ GOTO Example: CNT, 1, 1 LOOP CONTINUE Before Instruction PC = After Instruction CNT = If CNT = PC = If CNT PC = Address (HERE) CNT - 1 0; Address (CONTINUE) 0; Address (HERE + 2) (c) 2008 Microchip Technology Inc. ffff ffff 3 cycles if skip and followed by a 2-word instruction. Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Q1 Q2 Q3 Q4 No operation No operation No operation No operation If skip: If skip and followed by 2-word instruction: 11da The contents of register `f' are decremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is not `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Q Cycle Activity: Q1 f {,d {,a}} If skip: If skip and followed by 2-word instruction: Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation Example: HERE ZERO NZERO Before Instruction TEMP After Instruction TEMP If TEMP PC If TEMP PC DCFSNZ : : TEMP, 1, 0 = ? = = = = TEMP - 1, 0; Address (ZERO) 0; Address (NZERO) DS39631E-page 287 PIC18F2420/2520/4420/4520 GOTO Unconditional Branch INCF Increment f Syntax: GOTO k Syntax: INCF Operands: 0 k 1048575 Operands: Operation: k PC<20:1> Status Affected: None 0 f 255 d [0,1] a [0,1] Operation: (f) + 1 dest Status Affected: C, DC, N, OV, Z Encoding: 1st word (k<7:0>) 2nd word(k<19:8>) 1110 1111 Description: 1111 k19kkk k7kkk kkkk kkkk0 kkkk8 GOTO allows an unconditional branch Encoding: 0010 2 Cycles: 2 Q1 Q2 Q3 Q4 Read literal `k'<7:0>, No operation Read literal `k'<19:8>, Write to PC No operation No operation No operation No operation ffff ffff The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Decode 10da Description: anywhere within entire 2-Mbyte memory range. The 20-bit value `k' is loaded into PC<20:1>. GOTO is always a two-cycle instruction. Words: f {,d {,a}} Q Cycle Activity: Example: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination GOTO THERE After Instruction PC = Address (THERE) Example: INCF Before Instruction CNT = Z = C = DC = After Instruction CNT = Z = C = DC = DS39631E-page 288 CNT, 1, 0 FFh 0 ? ? 00h 1 1 1 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 INCFSZ Increment f, Skip if 0 INFSNZ Syntax: INCFSZ Syntax: INFSNZ 0 f 255 d [0,1] a [0,1] f {,d {,a}} Increment f, Skip if Not 0 f {,d {,a}} Operands: 0 f 255 d [0,1] a [0,1] Operands: Operation: (f) + 1 dest, skip if result = 0 Operation: (f) + 1 dest, skip if result 0 Status Affected: None Status Affected: None Encoding: 0011 11da ffff ffff Encoding: 0100 Description: ffff ffff The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is not `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Description: The contents of register `f' are incremented. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If the result is `0', the next instruction, which is already fetched, is discarded and a NOP is executed instead, making it a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. Cycles: 1(2) Note: Q Cycle Activity: 10da 3 cycles if skip and followed by a 2-word instruction. Q Cycle Activity: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Decode Read register `f' Process Data Write to destination Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation If skip: If skip: If skip and followed by 2-word instruction: If skip and followed by 2-word instruction: Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation No operation Example: HERE NZERO ZERO Before Instruction PC = After Instruction CNT = If CNT = PC = If CNT PC = INCFSZ : : Address (HERE) CNT + 1 0; Address (ZERO) 0; Address (NZERO) (c) 2008 Microchip Technology Inc. CNT, 1, 0 Example: HERE ZERO NZERO Before Instruction PC = After Instruction REG = If REG PC = If REG = PC = INFSNZ REG, 1, 0 Address (HERE) REG + 1 0; Address (NZERO) 0; Address (ZERO) DS39631E-page 289 PIC18F2420/2520/4420/4520 IORLW Inclusive OR Literal with W IORWF Inclusive OR W with f Syntax: IORLW k Syntax: IORWF Operands: 0 k 255 Operands: Operation: (W) .OR. k W Status Affected: N, Z 0 f 255 d [0,1] a [0,1] Operation: (W) .OR. (f) dest Status Affected: N, Z Encoding: 0000 1001 kkkk kkkk Description: The contents of W are ORed with the 8-bit literal `k'. The result is placed in W. Words: 1 Cycles: 1 Encoding: 0001 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write to W Example: IORLW W = ffff Words: 1 Cycles: 1 35h 9Ah BFh ffff Inclusive OR W with register `f'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Before Instruction W = After Instruction 00da Description: Q Cycle Activity: Decode f {,d {,a}} Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: IORWF Before Instruction RESULT = W = After Instruction RESULT = W = DS39631E-page 290 RESULT, 0, 1 13h 91h 13h 93h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 LFSR Load FSR MOVF Move f Syntax: LFSR f, k Syntax: MOVF Operands: 0f2 0 k 4095 Operands: Operation: k FSRf 0 f 255 d [0,1] a [0,1] Status Affected: None Operation: f dest Status Affected: N, Z Encoding: 1110 1111 1110 0000 00ff k7kkk k11kkk kkkk Description: The 12-bit literal `k' is loaded into the File Select Register pointed to by `f'. Words: 2 Cycles: 2 Encoding: 0101 Q1 Q2 Q3 Q4 Read literal `k' MSB Process Data Write literal `k' MSB to FSRfH Decode Read literal `k' LSB Process Data Write literal `k' to FSRfL Example: After Instruction FSR2H FSR2L 03h ABh ffff ffff The contents of register `f' are moved to a destination dependent upon the status of `d'. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). Location `f' can be anywhere in the 256-byte bank. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 LFSR 2, 3ABh = = 00da Description: Q Cycle Activity: Decode f {,d {,a}} Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write W Example: MOVF Before Instruction REG W After Instruction REG W (c) 2008 Microchip Technology Inc. REG, 0, 0 = = 22h FFh = = 22h 22h DS39631E-page 291 PIC18F2420/2520/4420/4520 MOVFF Move f to f MOVLB Move Literal to Low Nibble in BSR Syntax: MOVFF fs,fd Syntax: MOVLW k Operands: 0 fs 4095 0 fd 4095 Operands: 0 k 255 Operation: k BSR None Operation: (fs) fd Status Affected: Status Affected: None Encoding: Encoding: 1st word (source) 2nd word (destin.) 1100 1111 Description: ffff ffff ffff ffff ffffs ffffd The contents of source register `fs' are moved to destination register `fd'. Location of source `fs' can be anywhere in the 4096-byte data space (000h to FFFh) and location of destination `fd' can also be anywhere from 000h to FFFh. Either source or destination can be W (a useful special situation). MOVFF is particularly useful for transferring a data memory location to a peripheral register (such as the transmit buffer or an I/O port). The MOVFF instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. Words: 2 Cycles: 2 (3) 0000 0001 kkkk kkkk Description: The 8-bit literal `k' is loaded into the Bank Select Register (BSR). The value of BSR<7:4> always remains `0', regardless of the value of k7:k4. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read literal `k' Process Data Write literal `k' to BSR MOVLB 5 Example: Before Instruction BSR Register = After Instruction BSR Register = 02h 05h Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' (src) Process Data No operation Decode No operation No operation Write register `f' (dest) No dummy read Example: MOVFF Before Instruction REG1 REG2 After Instruction REG1 REG2 DS39631E-page 292 REG1, REG2 = = 33h 11h = = 33h 33h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 MOVLW Move Literal to W MOVWF Move W to f Syntax: MOVLW k Syntax: MOVWF Operands: 0 k 255 Operands: Operation: kW 0 f 255 a [0,1] Status Affected: None Encoding: 0000 Description: 1110 kkkk kkkk The 8-bit literal `k' is loaded into W. Words: 1 Cycles: 1 Operation: (W) f Status Affected: None Encoding: 0110 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write to W Example: MOVLW = ffff ffff Move data from W to register `f'. Location `f' can be anywhere in the 256-byte bank. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 5Ah After Instruction W 111a Description: Q Cycle Activity: Decode f {,a} 5Ah Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: MOVWF REG, 0 Before Instruction W = REG = After Instruction W REG (c) 2008 Microchip Technology Inc. = = 4Fh FFh 4Fh 4Fh DS39631E-page 293 PIC18F2420/2520/4420/4520 MULLW Multiply Literal with W MULWF Multiply W with f Syntax: MULLW Syntax: MULWF Operands: 0 f 255 a [0,1] Operation: (W) x (f) PRODH:PRODL Status Affected: None k Operands: 0 k 255 Operation: (W) x k PRODH:PRODL Status Affected: None Encoding: 0000 Description: 1101 kkkk kkkk An unsigned multiplication is carried out between the contents of W and the 8-bit literal `k'. The 16-bit result is placed in the PRODH:PRODL register pair. PRODH contains the high byte. W is unchanged. None of the Status flags are affected. Note that neither Overflow nor Carry is possible in this operation. A zero result is possible but not detected. Words: 1 Cycles: 1 Encoding: 0000 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write registers PRODH: PRODL Example: MULLW W PRODH PRODL After Instruction W PRODH PRODL = = = E2h ? ? = = = E2h ADh 08h ffff ffff An unsigned multiplication is carried out between the contents of W and the register file location `f'. The 16-bit result is stored in the PRODH:PRODL register pair. PRODH contains the high byte. Both W and `f' are unchanged. None of the Status flags are affected. Note that neither Overflow nor Carry is possible in this operation. A zero result is possible but not detected. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 0C4h Before Instruction 001a Description: Q Cycle Activity: Decode f {,a} Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write registers PRODH: PRODL Example: MULWF REG, 1 Before Instruction W REG PRODH PRODL After Instruction W REG PRODH PRODL DS39631E-page 294 = = = = C4h B5h ? ? = = = = C4h B5h 8Ah 94h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 NEGF Negate f NOP No Operation Syntax: NEGF Syntax: NOP Operands: 0 f 255 a [0,1] f {,a} Operands: None Operation: No operation None Operation: (f)+1f Status Affected: Status Affected: N, OV, C, DC, Z Encoding: Encoding: 0110 Description: 110a ffff Location `f' is negated using two's complement. The result is placed in the data memory location `f'. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 0000 1111 ffff 0000 xxxx Description: No operation. Words: 1 Cycles: 1 0000 xxxx 0000 xxxx Q Cycle Activity: Q1 Q2 Q3 Q4 Decode No operation No operation No operation Example: None. Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: NEGF Before Instruction REG = After Instruction REG = REG, 1 0011 1010 [3Ah] 1100 0110 [C6h] (c) 2008 Microchip Technology Inc. DS39631E-page 295 PIC18F2420/2520/4420/4520 POP Pop Top of Return Stack PUSH Push Top of Return Stack Syntax: POP Syntax: PUSH Operands: None Operands: None Operation: (TOS) bit bucket Operation: (PC + 2) TOS Status Affected: None Status Affected: None Encoding: 0000 0000 0000 0110 Description: The TOS value is pulled off the return stack and is discarded. The TOS value then becomes the previous value that was pushed onto the return stack. This instruction is provided to enable the user to properly manage the return stack to incorporate a software stack. Words: 1 Cycles: 1 Encoding: 0000 0101 The PC + 2 is pushed onto the top of the return stack. The previous TOS value is pushed down on the stack. This instruction allows implementing a software stack by modifying TOS and then pushing it onto the return stack. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode No operation POP TOS value No operation POP GOTO NEW Q1 Q2 Q3 Q4 Decode PUSH PC + 2 onto return stack No operation No operation Example: Before Instruction TOS Stack (1 level down) = = 0031A2h 014332h After Instruction TOS PC = = 014332h NEW DS39631E-page 296 0000 Description: Q Cycle Activity: Example: 0000 PUSH Before Instruction TOS PC = = 345Ah 0124h After Instruction PC TOS Stack (1 level down) = = = 0126h 0126h 345Ah (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 RCALL Relative Call RESET Reset Syntax: RCALL Syntax: RESET n Operands: -1024 n 1023 Operands: None Operation: (PC) + 2 TOS, (PC) + 2 + 2n PC Operation: Reset all registers and flags that are affected by a MCLR Reset. Status Affected: None Status Affected: All Encoding: 1101 Description: 1nnn nnnn nnnn Subroutine call with a jump up to 1K from the current location. First, return address (PC + 2) is pushed onto the stack. Then, add the 2's complement number `2n' to the PC. Since the PC will have incremented to fetch the next instruction, the new address will be PC + 2 + 2n. This instruction is a two-cycle instruction. Words: 1 Cycles: 2 Encoding: 0000 Q1 Q2 Q3 Q4 Decode Read literal `n' Process Data Write to PC No operation No operation 1111 1111 This instruction provides a way to execute a MCLR Reset in software. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Start Reset No operation No operation Example: Q Cycle Activity: 0000 Description: After Instruction Registers = Flags* = RESET Reset Value Reset Value PUSH PC to stack No operation Example: No operation HERE RCALL Jump Before Instruction PC = Address (HERE) After Instruction PC = Address (Jump) TOS = Address (HERE + 2) (c) 2008 Microchip Technology Inc. DS39631E-page 297 PIC18F2420/2520/4420/4520 RETFIE Return from Interrupt RETLW Return Literal to W Syntax: RETFIE {s} Syntax: RETLW k Operands: s [0,1] Operands: 0 k 255 Operation: (TOS) PC, 1 GIE/GIEH or PEIE/GIEL; if s = 1, (WS) W, (STATUSS) STATUS, (BSRS) BSR, PCLATU, PCLATH are unchanged Operation: k W, (TOS) PC, PCLATU, PCLATH are unchanged Status Affected: None Status Affected: 0000 0000 0001 1 Cycles: 2 Q Cycle Activity: Q2 Q3 Q4 Decode No operation No operation POP PC from stack Set GIEH or GIEL No operation RETFIE After Interrupt PC W BSR STATUS GIE/GIEH, PEIE/GIEL DS39631E-page 298 kkkk kkkk W is loaded with the 8-bit literal `k'. The program counter is loaded from the top of the stack (the return address). The high address latch (PCLATH) remains unchanged. Words: 1 Cycles: 2 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read literal `k' Process Data POP PC from stack, Write to W No operation No operation No operation No operation Example: Q1 Example: 1100 Description: 000s Return from interrupt. Stack is popped and Top-of-Stack (TOS) is loaded into the PC. Interrupts are enabled by setting either the high or low-priority global interrupt enable bit. If `s' = 1, the contents of the shadow registers, WS, STATUSS and BSRS, are loaded into their corresponding registers, W, STATUS and BSR. If `s' = 0, no update of these registers occurs (default). Words: No operation 0000 GIE/GIEH, PEIE/GIEL. Encoding: Description: Encoding: No operation No operation 1 = = = = = TOS WS BSRS STATUSS 1 CALL TABLE ; ; ; ; : TABLE ADDWF PCL ; RETLW k0 ; RETLW k1 ; : : RETLW kn ; Before Instruction W = After Instruction W = W contains table offset value W now has table value W = offset Begin table End of table 07h value of kn (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 RETURN Return from Subroutine RLCF Rotate Left f through Carry Syntax: RETURN {s} Syntax: RLCF Operands: s [0,1] Operands: Operation: (TOS) PC; if s = 1, (WS) W, (STATUSS) STATUS, (BSRS) BSR, PCLATU, PCLATH are unchanged 0 f 255 d [0,1] a [0,1] Operation: (f<n>) dest<n + 1>, (f<7>) C, (C) dest<0> Status Affected: C, N, Z Status Affected: None Encoding: 0000 Encoding: 0000 0001 001s Description: Return from subroutine. The stack is popped and the top of the stack (TOS) is loaded into the program counter. If `s'= 1, the contents of the shadow registers, WS, STATUSS and BSRS, are loaded into their corresponding registers, W, STATUS and BSR. If `s' = 0, no update of these registers occurs (default). Words: 1 Cycles: 2 0011 Description: Q Cycle Activity: Q1 Q2 Q3 Q4 Decode No operation Process Data POP PC from stack No operation No operation No operation No operation f {,d {,a}} 01da ffff ffff The contents of register `f' are rotated one bit to the left through the Carry flag. If `d' is `0', the result is placed in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. register f C Words: 1 Cycles: 1 Q Cycle Activity: Example: RETURN After Instruction: PC = TOS Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: Before Instruction REG = C = After Instruction REG = W = C = (c) 2008 Microchip Technology Inc. RLCF REG, 0, 0 1110 0110 0 1110 0110 1100 1100 1 DS39631E-page 299 PIC18F2420/2520/4420/4520 RLNCF Rotate Left f (No Carry) RRCF Rotate Right f through Carry Syntax: RLNCF Syntax: RRCF Operands: 0 f 255 d [0,1] a [0,1] Operands: 0 f 255 d [0,1] a [0,1] Operation: (f<n>) dest<n + 1>, (f<7>) dest<0> Operation: Status Affected: N, Z (f<n>) dest<n - 1>, (f<0>) C, (C) dest<7> Status Affected: C, N, Z Encoding: 0100 Description: f {,d {,a}} 01da ffff ffff The contents of register `f' are rotated one bit to the left. If `d' is `0', the result is placed in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Encoding: 0011 Description: register f Words: 1 Cycles: 1 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Before Instruction REG = After Instruction REG = DS39631E-page 300 00da RLNCF Words: 1 Cycles: 1 0101 0111 ffff register f Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination RRCF REG, 0, 0 REG, 1, 0 1010 1011 ffff The contents of register `f' are rotated one bit to the right through the Carry flag. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. C Q Cycle Activity: Example: f {,d {,a}} Example: Before Instruction REG = C = After Instruction REG = W = C = 1110 0110 0 1110 0110 0111 0011 0 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 RRNCF Rotate Right f (No Carry) SETF Syntax: RRNCF Syntax: SETF Operands: 0 f 255 d [0,1] a [0,1] Operands: 0 f 255 a [0,1] Operation: (f<n>) dest<n - 1>, (f<0>) dest<7> FFh f Operation: Status Affected: None Status Affected: f {,d {,a}} Encoding: N, Z Encoding: 0100 Description: 00da ffff ffff The contents of register `f' are rotated one bit to the right. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed back in register `f' (default). If `a' is `0', the Access Bank will be selected, overriding the BSR value. If `a' is `1', then the bank will be selected as per the BSR value (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. register f Words: 1 Cycles: 1 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination RRNCF Before Instruction REG = After Instruction REG = Example 2: f {,a} 0110 100a ffff ffff Description: The contents of the specified register are set to FFh. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write register `f' Example: Q Cycle Activity: Example 1: Set f SETF Before Instruction REG After Instruction REG REG, 1 = 5Ah = FFh REG, 1, 0 1101 0111 1110 1011 RRNCF REG, 0, 0 Before Instruction W = REG = After Instruction W REG = = ? 1101 0111 1110 1011 1101 0111 (c) 2008 Microchip Technology Inc. DS39631E-page 301 PIC18F2420/2520/4420/4520 SLEEP Enter Sleep mode SUBFWB Subtract f from W with Borrow Syntax: SLEEP Syntax: SUBFWB Operands: None Operands: Operation: 00h WDT, 0 WDT postscaler, 1 TO, 0 PD 0 f 255 d [0,1] a [0,1] Operation: (W) - (f) - (C) dest Status Affected: N, OV, C, DC, Z Status Affected: TO, PD Encoding: 0000 Encoding: 0000 0000 0011 Description: The Power-Down status bit (PD) is cleared. The Time-out status bit (TO) is set. Watchdog Timer and its postscaler are cleared. The processor is put into Sleep mode with the oscillator stopped. Words: 1 Cycles: 1 0101 Q1 Q2 Q3 Q4 No operation Process Data Go to Sleep Example: SLEEP Before Instruction TO = ? ? PD = After Instruction 1 TO = 0 PD = If WDT causes wake-up, this bit is cleared. DS39631E-page 302 01da ffff ffff Description: Subtract register `f' and Carry flag (borrow) from W (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Decode f {,d {,a}} Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination SUBFWB REG, 1, 0 Example 1: Before Instruction REG = 3 W = 2 C = 1 After Instruction REG = FF W = 2 C = 0 Z = 0 N = 1 ; result is negative Example 2: SUBFWB REG, 0, 0 Before Instruction REG = 2 W = 5 C = 1 After Instruction REG = 2 W = 3 C = 1 Z = 0 N = 0 ; result is positive SUBFWB REG, 1, 0 Example 3: Before Instruction REG = 1 W = 2 C = 0 After Instruction REG = 0 W = 2 C = 1 Z = 1 ; result is zero N = 0 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 SUBLW Subtract W from Literal SUBWF Subtract W from f Syntax: SUBLW k Syntax: SUBWF Operands: 0 k 255 Operands: Operation: k - (W) W Status Affected: N, OV, C, DC, Z 0 f 255 d [0,1] a [0,1] Operation: (f) - (W) dest Status Affected: N, OV, C, DC, Z Encoding: 0000 1000 kkkk kkkk Description W is subtracted from the 8-bit literal `k'. The result is placed in W. Words: 1 Cycles: 1 Encoding: 0101 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write to W Example 1: Before Instruction W = C = After Instruction W = C = Z = N = Example 2: Before Instruction W = C = After Instruction W = C = Z = N = Example 3: Before Instruction W = C = After Instruction W = C = Z = N = SUBLW 02h 1 Cycles: 1 Q Cycle Activity: 02h ? 00h 1 ; result is zero 1 0 SUBLW ffff Words: 01h ? SUBLW ffff Subtract W from register `f' (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. 02h 01h 1 ; result is positive 0 0 11da Description: Q Cycle Activity: Decode f {,d {,a}} 02h 03h ? FFh ; (2's complement) 0 ; result is negative 0 1 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination SUBWF REG, 1, 0 Example 1: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 2: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 3: Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = (c) 2008 Microchip Technology Inc. 3 2 ? 1 2 1 0 0 ; result is positive SUBWF REG, 0, 0 2 2 ? 2 0 1 1 0 SUBWF ; result is zero REG, 1, 0 1 2 ? FFh ;(2's complement) 2 0 ; result is negative 0 1 DS39631E-page 303 PIC18F2420/2520/4420/4520 SUBWFB Subtract W from f with Borrow SWAPF Swap f Syntax: SUBWFB Syntax: SWAPF f {,d {,a}} Operands: 0 f 255 d [0,1] a [0,1] Operands: 0 f 255 d [0,1] a [0,1] Operation: (f) - (W) - (C) dest Operation: Status Affected: N, OV, C, DC, Z (f<3:0>) dest<7:4>, (f<7:4>) dest<3:0> Status Affected: None Encoding: 0101 Description: f {,d {,a}} 10da ffff ffff Subtract W and the Carry flag (borrow) from register `f' (2's complement method). If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Decode Q2 Read register `f' Example 1: SUBWFB Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 2: Q4 Write to destination (0001 1001) (0000 1101) 0Ch 0Dh 1 0 0 (0000 1011) (0000 1101) 10da ffff ffff The upper and lower nibbles of register `f' are exchanged. If `d' is `0', the result is placed in W. If `d' is `1', the result is placed in register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination REG, 1, 0 19h 0Dh 1 0011 Description: Example: SWAPF Before Instruction REG = After Instruction REG = REG, 1, 0 53h 35h ; result is positive SUBWFB REG, 0, 0 Before Instruction REG = W = C = After Instruction REG = W = C = Z = N = Example 3: 1Bh 1Ah 0 (0001 1011) (0001 1010) 1Bh 00h 1 1 0 (0001 1011) SUBWFB Before Instruction REG = W = C = After Instruction REG = W C Z N Q3 Process Data Encoding: = = = = DS39631E-page 304 ; result is zero REG, 1, 0 03h 0Eh 1 (0000 0011) (0000 1101) F5h (1111 0100) ; [2's comp] (0000 1101) 0Eh 0 0 1 ; result is negative (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TBLRD Table Read TBLRD Table Read (Continued) Syntax: TBLRD ( *; *+; *-; +*) Example1: TBLRD Operands: None Operation: if TBLRD *, (Prog Mem (TBLPTR)) TABLAT, TBLPTR - No Change; if TBLRD *+, (Prog Mem (TBLPTR)) TABLAT, (TBLPTR) + 1 TBLPTR; if TBLRD *-, (Prog Mem (TBLPTR)) TABLAT, (TBLPTR) - 1 TBLPTR; if TBLRD +*, (TBLPTR) + 1 TBLPTR, (Prog Mem (TBLPTR)) TABLAT Before Instruction TABLAT TBLPTR MEMORY (00A356h) After Instruction TABLAT TBLPTR Example2: 0000 0000 0000 TBLRD = = = 55h 00A356h 34h = = 34h 00A357h +* ; Before Instruction TABLAT TBLPTR MEMORY (01A357h) MEMORY (01A358h) After Instruction TABLAT TBLPTR Status Affected: None Encoding: *+ ; = = = = AAh 01A357h 12h 34h = = 34h 01A358h 10nn nn=0 * =1 *+ =2 *=3 +* Description: This instruction is used to read the contents of Program Memory (P.M.). To address the program memory, a pointer called Table Pointer (TBLPTR) is used. The TBLPTR (a 21-bit pointer) points to each byte in the program memory. TBLPTR has a 2-Mbyte address range. TBLPTR<0> = 0:Least Significant Byte of Program Memory Word TBLPTR<0> = 1:Most Significant Byte of Program Memory Word The TBLRD instruction can modify the value of TBLPTR as follows: * no change * post-increment * post-decrement * pre-increment Words: 1 Cycles: 2 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode No operation No operation No operation No operation No operation (Read Program Memory) No operation No operation (Write TABLAT) (c) 2008 Microchip Technology Inc. DS39631E-page 305 PIC18F2420/2520/4420/4520 TBLWT Table Write TBLWT Table Write (Continued) Syntax: TBLWT ( *; *+; *-; +*) Example1: TBLWT *+; Operands: None Operation: if TBLWT*, (TABLAT) Holding Register, TBLPTR - No Change; if TBLWT*+, (TABLAT) Holding Register, (TBLPTR) + 1 TBLPTR; if TBLWT*-, (TABLAT) Holding Register, (TBLPTR) - 1 TBLPTR; if TBLWT+*, (TBLPTR) + 1 TBLPTR, (TABLAT) Holding Register Status Affected: Before Instruction TABLAT = 55h TBLPTR = 00A356h HOLDING REGISTER (00A356h) = FFh After Instructions (table write completion) TABLAT = 55h TBLPTR = 00A357h HOLDING REGISTER (00A356h) = 55h Example 2: None Encoding: 0000 0000 0000 11nn nn=0 * =1 *+ =2 *=3 +* Description: This instruction uses the 3 LSBs of TBLPTR to determine which of the 8 holding registers the TABLAT is written to. The holding registers are used to program the contents of Program Memory (P.M.). (Refer to Section 6.0 "Flash Program Memory" for additional details on programming Flash memory.) The TBLPTR (a 21-bit pointer) points to each byte in the program memory. TBLPTR has a 2-MByte address range. The LSb of the TBLPTR selects which byte of the program memory location to access. TBLPTR<0> = 0:Least Significant Byte of Program Memory Word TBLPTR<0> = 1:Most Significant Byte of Program Memory Word The TBLWT instruction can modify the value of TBLPTR as follows: * no change * post-increment * post-decrement * pre-increment Words: 1 Cycles: 2 TBLWT +*; Before Instruction TABLAT = 34h TBLPTR = 01389Ah HOLDING REGISTER (01389Ah) = FFh HOLDING REGISTER (01389Bh) = FFh After Instruction (table write completion) TABLAT = 34h TBLPTR = 01389Bh HOLDING REGISTER (01389Ah) = FFh HOLDING REGISTER (01389Bh) = 34h Q Cycle Activity: Q1 Decode Q2 Q3 Q4 No No No operation operation operation No No No No operation operation operation operation (Write to (Read Holding TABLAT) Register ) DS39631E-page 306 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TSTFSZ Test f, Skip if 0 XORLW Exclusive OR Literal with W Syntax: TSTFSZ f {,a} Syntax: XORLW k Operands: 0 f 255 a [0,1] Operands: 0 k 255 Operation: (W) .XOR. k W Status Affected: N, Z Operation: skip if f = 0 Status Affected: None Encoding: Encoding: 0110 Description: 011a ffff ffff If `f' = 0, the next instruction fetched during the current instruction execution is discarded and a NOP is executed, making this a two-cycle instruction. If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1(2) Note: 3 cycles if skip and followed by a 2-word instruction. 0000 1010 kkkk kkkk Description: The contents of W are XORed with the 8-bit literal `k'. The result is placed in W. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read literal `k' Process Data Write to W Example: XORLW 0AFh Before Instruction W = After Instruction W = B5h 1Ah Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data No operation Q1 Q2 Q3 Q4 No operation No operation No operation No operation If skip: If skip and followed by 2-word instruction: Q1 Q2 Q3 Q4 No operation No operation No operation No operation No operation No operation No operation No operation Example: HERE NZERO ZERO Before Instruction PC After Instruction If CNT PC If CNT PC TSTFSZ : : CNT, 1 = Address (HERE) = = = 00h, Address (ZERO) 00h, Address (NZERO) (c) 2008 Microchip Technology Inc. DS39631E-page 307 PIC18F2420/2520/4420/4520 XORWF Exclusive OR W with f Syntax: XORWF Operands: 0 f 255 d [0,1] a [0,1] Operation: (W) .XOR. (f) dest Status Affected: N, Z Encoding: 0001 f {,d {,a}} 10da ffff ffff Description: Exclusive OR the contents of W with register `f'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in the register `f' (default). If `a' is `0', the Access Bank is selected. If `a' is `1', the BSR is used to select the GPR bank (default). If `a' is `0' and the extended instruction set is enabled, this instruction operates in Indexed Literal Offset Addressing mode whenever f 95 (5Fh). See Section 24.2.3 "Byte-Oriented and Bit-Oriented Instructions in Indexed Literal Offset Mode" for details. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination Example: XORWF Before Instruction REG = W = After Instruction REG = W = DS39631E-page 308 REG, 1, 0 AFh B5h 1Ah B5h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 24.2 A summary of the instructions in the extended instruction set is provided in Table 24-3. Detailed descriptions are provided in Section 24.2.2 "Extended Instruction Set". The opcode field descriptions in Table 24-1 (page 268) apply to both the standard and extended PIC18 instruction sets. Extended Instruction Set In addition to the standard 75 instructions of the PIC18 instruction set, PIC18F2420/2520/4420/4520 devices also provide an optional extension to the core CPU functionality. The added features include eight additional instructions that augment indirect and indexed addressing operations and the implementation of Indexed Literal Offset Addressing mode for many of the standard PIC18 instructions. Note: The additional features of the extended instruction set are disabled by default. To enable them, users must set the XINST Configuration bit. The instructions in the extended set can all be classified as literal operations, which either manipulate the File Select Registers, or use them for indexed addressing. Two of the instructions, ADDFSR and SUBFSR, each have an additional special instantiation for using FSR2. These versions (ADDULNK and SUBULNK) allow for automatic return after execution. 24.2.1 EXTENDED INSTRUCTION SYNTAX Most of the extended instructions use indexed arguments, using one of the File Select Registers and some offset to specify a source or destination register. When an argument for an instruction serves as part of indexed addressing, it is enclosed in square brackets ("[ ]"). This is done to indicate that the argument is used as an index or offset. MPASMTM Assembler will flag an error if it determines that an index or offset value is not bracketed. The extended instructions are specifically implemented to optimize re-entrant program code (that is, code that is recursive or that uses a software stack) written in high-level languages, particularly C. Among other things, they allow users working in high-level languages to perform certain operations on data structures more efficiently. These include: When the extended instruction set is enabled, brackets are also used to indicate index arguments in byteoriented and bit-oriented instructions. This is in addition to other changes in their syntax. For more details, see Section 24.2.3.1 "Extended Instruction Syntax with Standard PIC18 Commands". * Dynamic allocation and deallocation of software stack space when entering and leaving subroutines * Function Pointer invocation * Software Stack Pointer manipulation * Manipulation of variables located in a software stack TABLE 24-3: The instruction set extension and the Indexed Literal Offset Addressing mode were designed for optimizing applications written in C; the user may likely never use these instructions directly in assembler. The syntax for these commands is provided as a reference for users who may be reviewing code that has been generated by a compiler. Note: In the past, square brackets have been used to denote optional arguments in the PIC18 and earlier instruction sets. In this text and going forward, optional arguments are denoted by braces ("{ }"). EXTENSIONS TO THE PIC18 INSTRUCTION SET 16-Bit Instruction Word Mnemonic, Operands ADDFSR ADDULNK CALLW MOVSF f, k k MOVSS zs, zd PUSHL k SUBFSR SUBULNK f, k k zs, fd Description Cycles MSb Add Literal to FSR Add Literal to FSR2 and Return Call Subroutine using WREG Move zs (source) to 1st word fd (destination) 2nd word Move zs (source) to 1st word 2nd word zd (destination) Store Literal at FSR2, Decrement FSR2 Subtract Literal from FSR Subtract Literal from FSR2 and Return (c) 2008 Microchip Technology Inc. 1 2 2 2 LSb Status Affected 1000 1000 0000 1011 ffff 1011 xxxx 1010 ffkk 11kk 0001 0zzz ffff 1zzz xzzz kkkk kkkk kkkk 0100 zzzz ffff zzzz zzzz kkkk None None None None 1 1110 1110 0000 1110 1111 1110 1111 1110 1 2 1110 1110 1001 1001 ffkk 11kk kkkk kkkk None None 2 None None DS39631E-page 309 PIC18F2420/2520/4420/4520 24.2.2 EXTENDED INSTRUCTION SET ADDFSR Add Literal to FSR ADDULNK Syntax: ADDFSR f, k Syntax: ADDULNK k Operands: 0 k 63 f [ 0, 1, 2 ] Operands: 0 k 63 Operation: FSR(f) + k FSR(f) Status Affected: None Encoding: 1110 Add Literal to FSR2 and Return FSR2 + k FSR2, Operation: (TOS) PC Status Affected: 1000 ffkk kkkk Description: The 6-bit literal `k' is added to the contents of the FSR specified by `f'. Words: 1 Cycles: 1 None Encoding: 1110 Q1 Q2 Q3 Q4 Read literal `k' Process Data Write to FSR Example: ADDFSR 2, 23h Before Instruction FSR2 = 03FFh After Instruction FSR2 = 0422h kkkk Words: 1 Cycles: 2 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read literal `k' Process Data Write to FSR No Operation No Operation No Operation No Operation Example: Note: 11kk The 6-bit literal `k' is added to the contents of FSR2. A RETURN is then executed by loading the PC with the TOS. The instruction takes two cycles to execute; a NOP is performed during the second cycle. This may be thought of as a special case of the ADDFSR instruction, where f = 3 (binary `11'); it operates only on FSR2. Q Cycle Activity: Decode 1000 Description: ADDULNK 23h Before Instruction FSR2 = PC = 03FFh 0100h After Instruction FSR2 = PC = 0422h (TOS) All PIC18 instructions may take an optional label argument preceding the instruction mnemonic for use in symbolic addressing. If a label is used, the instruction syntax then becomes: {label} instruction argument(s). DS39631E-page 310 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 CALLW Subroutine Call Using WREG MOVSF Syntax: CALLW Syntax: MOVSF [zs], fd Operands: None Operands: Operation: (PC + 2) TOS, (W) PCL, (PCLATH) PCH, (PCLATU) PCU 0 zs 127 0 fd 4095 Operation: ((FSR2) + zs) fd Status Affected: None Status Affected: None Encoding: 0000 0000 0001 0100 Description First, the return address (PC + 2) is pushed onto the return stack. Next, the contents of W are written to PCL; the existing value is discarded. Then, the contents of PCLATH and PCLATU are latched into PCH and PCU, respectively. The second cycle is executed as a NOP instruction while the new next instruction is fetched. Unlike CALL, there is no option to update W, STATUS or BSR. Words: 1 Cycles: 2 Move Indexed to f Encoding: 1st word (source) 2nd word (destin.) Q1 Q2 Q3 Q4 Read WREG PUSH PC to stack No operation No operation No operation No operation No operation HERE Before Instruction PC = PCLATH = PCLATU = W = After Instruction PC = TOS = PCLATH = PCLATU = W = 2 Cycles: 2 Q Cycle Activity: Q1 Decode address (HERE) 10h 00h 06h (c) 2008 Microchip Technology Inc. zzzzs ffffd Words: CALLW 001006h address (HERE + 2) 10h 00h 06h 0zzz ffff The contents of the source register are moved to destination register `fd'. The actual address of the source register is determined by adding the 7-bit literal offset `zs' in the first word to the value of FSR2. The address of the destination register is specified by the 12-bit literal `fd' in the second word. Both addresses can be anywhere in the 4096-byte data space (000h to FFFh). The MOVSF instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. If the resultant source address points to an indirect addressing register, the value returned will be 00h. Decode Example: 1011 ffff Description: Q Cycle Activity: Decode 1110 1111 Q2 Q3 Determine Determine source addr source addr No operation No operation No dummy read Example: MOVSF Before Instruction FSR2 Contents of 85h REG2 After Instruction FSR2 Contents of 85h REG2 Q4 Read source reg Write register `f' (dest) [05h], REG2 = 80h = = 33h 11h = 80h = = 33h 33h DS39631E-page 311 PIC18F2420/2520/4420/4520 MOVSS Move Indexed to Indexed PUSHL Syntax: Syntax: PUSHL k Operands: MOVSS [zs], [zd] 0 zs 127 0 zd 127 Operands: 0 k 255 Operation: ((FSR2) + zs) ((FSR2) + zd) Operation: k (FSR2), FSR2 - 1 FSR2 Status Affected: None Status Affected: None Encoding: 1st word (source) 2nd word (dest.) 1110 1111 Description 1011 xxxx 1zzz xzzz zzzzs zzzzd The contents of the source register are moved to the destination register. The addresses of the source and destination registers are determined by adding the 7-bit literal offsets `zs' or `zd', respectively, to the value of FSR2. Both registers can be located anywhere in the 4096-byte data memory space (000h to FFFh). The MOVSS instruction cannot use the PCL, TOSU, TOSH or TOSL as the destination register. If the resultant source address points to an indirect addressing register, the value returned will be 00h. If the resultant destination address points to an indirect addressing register, the instruction will execute as a NOP. Words: 2 Cycles: 2 Q Cycle Activity: Q1 Decode Decode Q2 Q3 Determine Determine source addr source addr Determine dest addr Example: Encoding: 1111 1010 kkkk kkkk Description: The 8-bit literal `k' is written to the data memory address specified by FSR2. FSR2 is decremented by 1 after the operation. This instruction allows users to push values onto a software stack. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read `k' Process data Write to destination Example: PUSHL 08h Before Instruction FSR2H:FSR2L Memory (01ECh) = = 01ECh 00h After Instruction FSR2H:FSR2L Memory (01ECh) = = 01EBh 08h Q4 Read source reg Write to dest reg MOVSS [05h], [06h] Before Instruction FSR2 Contents of 85h Contents of 86h After Instruction FSR2 Contents of 85h Contents of 86h DS39631E-page 312 Determine dest addr Store Literal at FSR2, Decrement FSR2 = 80h = 33h = 11h = 80h = 33h = 33h (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 SUBFSR Subtract Literal from FSR SUBULNK Syntax: SUBFSR f, k Syntax: SUBULNK k Operands: 0 k 63 Operands: 0 k 63 f [ 0, 1, 2 ] Operation: Operation: FSR(f) - k FSRf Status Affected: None Encoding: 1110 FSR2 - k FSR2, (TOS) PC Status Affected: None 1001 ffkk kkkk Description: The 6-bit literal `k' is subtracted from the contents of the FSR specified by `f'. Words: 1 Cycles: 1 Encoding: 1110 Q1 Q2 Q3 Q4 Decode Read register `f' Process Data Write to destination SUBFSR 2, 23h 1001 11kk kkkk Description: The 6-bit literal `k' is subtracted from the contents of the FSR2. A RETURN is then executed by loading the PC with the TOS. The instruction takes two cycles to execute; a NOP is performed during the second cycle. This may be thought of as a special case of the SUBFSR instruction, where f = 3 (binary `11'); it operates only on FSR2. Words: 1 Cycles: 2 Q Cycle Activity: Example: Subtract Literal from FSR2 and Return Q Cycle Activity: Before Instruction FSR2 = Q1 Q2 Q3 Q4 03FFh Decode After Instruction FSR2 = Read register `f' Process Data Write to destination 03DCh No Operation No Operation No Operation No Operation Example: (c) 2008 Microchip Technology Inc. SUBULNK 23h Before Instruction FSR2 = PC = 03FFh 0100h After Instruction FSR2 = PC = 03DCh (TOS) DS39631E-page 313 PIC18F2420/2520/4420/4520 24.2.3 Note: BYTE-ORIENTED AND BIT-ORIENTED INSTRUCTIONS IN INDEXED LITERAL OFFSET MODE Enabling the PIC18 instruction set extension may cause legacy applications to behave erratically or fail entirely. In addition to eight new commands in the extended set, enabling the extended instruction set also enables Indexed Literal Offset Addressing mode (Section 5.5.1 "Indexed Addressing with Literal Offset"). This has a significant impact on the way that many commands of the standard PIC18 instruction set are interpreted. When the extended set is disabled, addresses embedded in opcodes are treated as literal memory locations: either as a location in the Access Bank (`a' = 0), or in a GPR bank designated by the BSR (`a' = 1). When the extended instruction set is enabled and `a' = 0, however, a file register argument of 5Fh or less is interpreted as an offset from the pointer value in FSR2 and not as a literal address. For practical purposes, this means that all instructions that use the Access RAM bit as an argument - that is, all byte-oriented and bitoriented instructions, or almost half of the core PIC18 instructions - may behave differently when the extended instruction set is enabled. When the content of FSR2 is 00h, the boundaries of the Access RAM are essentially remapped to their original values. This may be useful in creating backward compatible code. If this technique is used, it may be necessary to save the value of FSR2 and restore it when moving back and forth between C and assembly routines in order to preserve the Stack Pointer. Users must also keep in mind the syntax requirements of the extended instruction set (see Section 24.2.3.1 "Extended Instruction Syntax with Standard PIC18 Commands"). Although the Indexed Literal Offset Addressing mode can be very useful for dynamic stack and pointer manipulation, it can also be very annoying if a simple arithmetic operation is carried out on the wrong register. Users who are accustomed to the PIC18 programming must keep in mind that, when the extended instruction set is enabled, register addresses of 5Fh or less are used for Indexed Literal Offset Addressing. Representative examples of typical byte-oriented and bit-oriented instructions in the Indexed Literal Offset Addressing mode are provided on the following page to show how execution is affected. The operand conditions shown in the examples are applicable to all instructions of these types. DS39631E-page 314 24.2.3.1 Extended Instruction Syntax with Standard PIC18 Commands When the extended instruction set is enabled, the file register argument, `f', in the standard byte-oriented and bit-oriented commands is replaced with the literal offset value, `k'. As already noted, this occurs only when `f' is less than or equal to 5Fh. When an offset value is used, it must be indicated by square brackets ("[ ]"). As with the extended instructions, the use of brackets indicates to the compiler that the value is to be interpreted as an index or an offset. Omitting the brackets, or using a value greater than 5Fh within brackets, will generate an error in the MPASM Assembler. If the index argument is properly bracketed for Indexed Literal Offset Addressing, the Access RAM argument is never specified; it will automatically be assumed to be `0'. This is in contrast to standard operation (extended instruction set disabled) when `a' is set on the basis of the target address. Declaring the Access RAM bit in this mode will also generate an error in the MPASM Assembler. The destination argument, `d', functions as before. In the latest versions of the MPASM assembler, language support for the extended instruction set must be explicitly invoked. This is done with either the command line option, /y, or the PE directive in the source listing. 24.2.4 CONSIDERATIONS WHEN ENABLING THE EXTENDED INSTRUCTION SET It is important to note that the extensions to the instruction set may not be beneficial to all users. In particular, users who are not writing code that uses a software stack may not benefit from using the extensions to the instruction set. Additionally, the Indexed Literal Offset Addressing mode may create issues with legacy applications written to the PIC18 assembler. This is because instructions in the legacy code may attempt to address registers in the Access Bank below 5Fh. Since these addresses are interpreted as literal offsets to FSR2 when the instruction set extension is enabled, the application may read or write to the wrong data addresses. When porting an application to the PIC18F2420/2520/ 4420/4520, it is very important to consider the type of code. A large, re-entrant application that is written in `C' and would benefit from efficient compilation will do well when using the instruction set extensions. Legacy applications that heavily use the Access Bank will most likely not benefit from using the extended instruction set. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 ADDWF ADD W to Indexed (Indexed Literal Offset mode) BSF Bit Set Indexed (Indexed Literal Offset mode) Syntax: ADDWF Syntax: BSF [k], b Operands: 0 k 95 d [0,1] Operands: 0 f 95 0b7 Operation: (W) + ((FSR2) + k) dest Operation: 1 ((FSR2) + k)<b> Status Affected: N, OV, C, DC, Z Status Affected: None Encoding: [k] {,d} 0010 Description: 01d0 kkkk kkkk The contents of W are added to the contents of the register indicated by FSR2, offset by the value `k'. If `d' is `0', the result is stored in W. If `d' is `1', the result is stored back in register `f' (default). Encoding: 1000 bbb0 kkkk kkkk Description: Bit `b' of the register indicated by FSR2, offset by the value `k', is set. Words: 1 Cycles: 1 Q Cycle Activity: Words: 1 Q1 Q2 Q3 Q4 Cycles: 1 Decode Read register `f' Process Data Write to destination Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read `k' Process Data Write to destination Example: ADDWF [OFST] , 0 Before Instruction W OFST FSR2 Contents of 0A2Ch After Instruction W Contents of 0A2Ch = = = 17h 2Ch 0A00h = 20h = 37h = 20h Example: BSF Before Instruction FLAG_OFST FSR2 Contents of 0A0Ah After Instruction Contents of 0A0Ah [FLAG_OFST], 7 = = 0Ah 0A00h = 55h = D5h SETF Set Indexed (Indexed Literal Offset mode) Syntax: SETF [k] Operands: 0 k 95 Operation: FFh ((FSR2) + k) Status Affected: None Encoding: 0110 1000 kkkk kkkk Description: The contents of the register indicated by FSR2, offset by `k', are set to FFh. Words: 1 Cycles: 1 Q Cycle Activity: Q1 Q2 Q3 Q4 Decode Read `k' Process Data Write register Example: SETF Before Instruction OFST FSR2 Contents of 0A2Ch After Instruction Contents of 0A2Ch (c) 2008 Microchip Technology Inc. [OFST] = = 2Ch 0A00h = 00h = FFh DS39631E-page 315 PIC18F2420/2520/4420/4520 24.2.5 SPECIAL CONSIDERATIONS WITH MICROCHIP MPLAB(R) IDE TOOLS The latest versions of Microchip's software tools have been designed to fully support the extended instruction set of the PIC18F2420/2520/4420/4520 family of devices. This includes the MPLAB C18 C compiler, MPASM assembly language and MPLAB Integrated Development Environment (IDE). When selecting a target device for software development, MPLAB IDE will automatically set default Configuration bits for that device. The default setting for the XINST Configuration bit is `0', disabling the extended instruction set and Indexed Literal Offset Addressing mode. For proper execution of applications developed to take advantage of the extended instruction set, XINST must be set during programming. DS39631E-page 316 To develop software for the extended instruction set, the user must enable support for the instructions and the Indexed Addressing mode in their language tool(s). Depending on the environment being used, this may be done in several ways: * A menu option, or dialog box within the environment, that allows the user to configure the language tool and its settings for the project * A command line option * A directive in the source code These options vary between different compilers, assemblers and development environments. Users are encouraged to review the documentation accompanying their development systems for the appropriate information. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 25.0 DEVELOPMENT SUPPORT The PIC(R) microcontrollers are supported with a full range of hardware and software development tools: * Integrated Development Environment - MPLAB(R) IDE Software * Assemblers/Compilers/Linkers - MPASMTM Assembler - MPLAB C18 and MPLAB C30 C Compilers - MPLINKTM Object Linker/ MPLIBTM Object Librarian - MPLAB ASM30 Assembler/Linker/Library * Simulators - MPLAB SIM Software Simulator * Emulators - MPLAB ICE 2000 In-Circuit Emulator - MPLAB REAL ICETM In-Circuit Emulator * In-Circuit Debugger - MPLAB ICD 2 * Device Programmers - PICSTART(R) Plus Development Programmer - MPLAB PM3 Device Programmer - PICkitTM 2 Development Programmer * Low-Cost Demonstration and Development Boards and Evaluation Kits 25.1 MPLAB Integrated Development Environment Software The MPLAB IDE software brings an ease of software development previously unseen in the 8/16-bit microcontroller market. The MPLAB IDE is a Windows(R) operating system-based application that contains: * A single graphical interface to all debugging tools - Simulator - Programmer (sold separately) - Emulator (sold separately) - In-Circuit Debugger (sold separately) * A full-featured editor with color-coded context * A multiple project manager * Customizable data windows with direct edit of contents * High-level source code debugging * Visual device initializer for easy register initialization * Mouse over variable inspection * Drag and drop variables from source to watch windows * Extensive on-line help * Integration of select third party tools, such as HI-TECH Software C Compilers and IAR C Compilers The MPLAB IDE allows you to: * Edit your source files (either assembly or C) * One touch assemble (or compile) and download to PIC MCU emulator and simulator tools (automatically updates all project information) * Debug using: - Source files (assembly or C) - Mixed assembly and C - Machine code MPLAB IDE supports multiple debugging tools in a single development paradigm, from the cost-effective simulators, through low-cost in-circuit debuggers, to full-featured emulators. This eliminates the learning curve when upgrading to tools with increased flexibility and power. (c) 2008 Microchip Technology Inc. DS39631E-page 317 PIC18F2420/2520/4420/4520 25.2 MPASM Assembler The MPASM Assembler is a full-featured, universal macro assembler for all PIC MCUs. The MPASM Assembler generates relocatable object files for the MPLINK Object Linker, Intel(R) standard HEX files, MAP files to detail memory usage and symbol reference, absolute LST files that contain source lines and generated machine code and COFF files for debugging. The MPASM Assembler features include: * Integration into MPLAB IDE projects * User-defined macros to streamline assembly code * Conditional assembly for multi-purpose source files * Directives that allow complete control over the assembly process 25.5 MPLAB ASM30 Assembler produces relocatable machine code from symbolic assembly language for dsPIC30F devices. MPLAB C30 C Compiler uses the assembler to produce its object file. The assembler generates relocatable object files that can then be archived or linked with other relocatable object files and archives to create an executable file. Notable features of the assembler include: * * * * * * Support for the entire dsPIC30F instruction set Support for fixed-point and floating-point data Command line interface Rich directive set Flexible macro language MPLAB IDE compatibility 25.6 25.3 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 microcontrollers and the dsPIC30 and dsPIC33 family of digital signal controllers. These compilers provide powerful integration capabilities, superior code optimization and ease of use not found with other compilers. For easy source level debugging, the compilers provide symbol information that is optimized to the MPLAB IDE debugger. 25.4 MPLINK Object Linker/ MPLIB Object Librarian The MPLINK Object Linker combines relocatable objects created by the MPASM Assembler and the MPLAB C18 C Compiler. It can link relocatable objects from precompiled libraries, using directives from a linker script. MPLAB ASM30 Assembler, Linker and Librarian MPLAB SIM Software Simulator The MPLAB SIM Software Simulator allows code development in a PC-hosted environment by simulating the PIC MCUs and dsPIC(R) DSCs on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a comprehensive stimulus controller. Registers can be logged to files for further run-time analysis. The trace buffer and logic analyzer display extend the power of the simulator to record and track program execution, actions on I/O, most peripherals and internal registers. The MPLAB SIM Software Simulator fully supports symbolic debugging using the MPLAB C18 and MPLAB C30 C Compilers, and the MPASM and MPLAB ASM30 Assemblers. The software simulator offers the flexibility to develop and debug code outside of the hardware laboratory environment, making it an excellent, economical software development tool. The MPLIB Object Librarian manages the creation and modification of library files of precompiled code. When a routine from a library is called from a source file, only the modules that contain that routine will be linked in with the application. This allows large libraries to be used efficiently in many different applications. The object linker/library features include: * Efficient linking of single libraries instead of many smaller files * Enhanced code maintainability by grouping related modules together * Flexible creation of libraries with easy module listing, replacement, deletion and extraction DS39631E-page 318 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 25.7 MPLAB ICE 2000 High-Performance In-Circuit Emulator The MPLAB ICE 2000 In-Circuit Emulator is intended to provide the product development engineer with a complete microcontroller design tool set for PIC microcontrollers. Software control of the MPLAB ICE 2000 In-Circuit Emulator is advanced by the MPLAB Integrated Development Environment, which allows editing, building, downloading and source debugging from a single environment. The MPLAB ICE 2000 is a full-featured emulator system with enhanced trace, trigger and data monitoring features. Interchangeable processor modules allow the system to be easily reconfigured for emulation of different processors. The architecture of the MPLAB ICE 2000 In-Circuit Emulator allows expansion to support new PIC microcontrollers. The MPLAB ICE 2000 In-Circuit Emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. The PC platform and Microsoft(R) Windows(R) 32-bit operating system were chosen to best make these features available in a simple, unified application. 25.8 MPLAB REAL ICE In-Circuit Emulator System MPLAB REAL ICE In-Circuit Emulator System is Microchip's next generation high-speed emulator for Microchip Flash DSC and MCU devices. It debugs and programs PIC(R) Flash MCUs and dsPIC(R) Flash DSCs with the easy-to-use, powerful graphical user interface of the MPLAB Integrated Development Environment (IDE), included with each kit. The MPLAB REAL ICE probe is connected to the design engineer's PC using a high-speed USB 2.0 interface and is connected to the target with either a connector compatible with the popular MPLAB ICD 2 system (RJ11) or with the new high-speed, noise tolerant, LowVoltage Differential Signal (LVDS) interconnection (CAT5). 25.9 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 costeffective, in-circuit Flash debugging from the graphical user interface of the MPLAB Integrated Development Environment. This enables a designer to develop and debug source code by setting breakpoints, single stepping 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. 25.10 MPLAB PM3 Device Programmer The MPLAB PM3 Device Programmer is a universal, CE compliant device programmer with programmable voltage verification at VDDMIN and VDDMAX for maximum reliability. It features a large LCD display (128 x 64) for menus and error messages and a modular, detachable socket assembly to support various package types. The ICSPTM cable assembly is included as a standard item. In Stand-Alone mode, the MPLAB PM3 Device Programmer can read, verify and program PIC devices without a PC connection. It can also set code protection in this mode. The MPLAB PM3 connects to the host PC via an RS-232 or USB cable. The MPLAB PM3 has high-speed communications and optimized algorithms for quick programming of large memory devices and incorporates an SD/MMC card for file storage and secure data applications. MPLAB REAL ICE is field upgradeable through future firmware downloads in MPLAB IDE. In upcoming releases of MPLAB IDE, new devices will be supported, and new features will be added, such as software breakpoints 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. (c) 2008 Microchip Technology Inc. DS39631E-page 319 PIC18F2420/2520/4420/4520 25.11 PICSTART Plus Development Programmer 25.13 Demonstration, Development and Evaluation Boards The PICSTART Plus Development Programmer is an easy-to-use, low-cost, prototype programmer. It connects to the PC via a COM (RS-232) port. MPLAB Integrated Development Environment software makes using the programmer simple and efficient. The PICSTART Plus Development Programmer supports most PIC devices in DIP packages up to 40 pins. Larger pin count devices, such as the PIC16C92X and PIC17C76X, may be supported with an adapter socket. The PICSTART Plus Development Programmer is CE compliant. A wide variety of demonstration, development and evaluation boards for various PIC MCUs and dsPIC DSCs allows quick application development on fully functional systems. Most boards include prototyping areas for adding custom circuitry and provide application firmware and source code for examination and modification. 25.12 PICkit 2 Development Programmer The PICkitTM 2 Development Programmer is a low-cost programmer and selected Flash device debugger with an easy-to-use interface for programming many of Microchip's baseline, mid-range and PIC18F families of Flash memory microcontrollers. The PICkit 2 Starter Kit includes a prototyping development board, twelve sequential lessons, software and HI-TECH's PICCTM Lite C compiler, and is designed to help get up to speed quickly using PIC(R) microcontrollers. The kit provides everything needed to program, evaluate and develop applications using Microchip's powerful, mid-range Flash memory family of microcontrollers. DS39631E-page 320 The boards support a variety of features, including LEDs, temperature sensors, switches, speakers, RS-232 interfaces, LCD displays, potentiometers and additional EEPROM memory. The demonstration and development boards can be used in teaching environments, for prototyping custom circuits and for learning about various microcontroller applications. In addition to the PICDEMTM and dsPICDEMTM demonstration/development board series of circuits, Microchip has a line of evaluation kits and demonstration software for analog filter design, KEELOQ(R) security ICs, CAN, IrDA(R), PowerSmart battery management, SEEVAL(R) evaluation system, Sigma-Delta ADC, flow rate sensing, plus many more. Check the Microchip web page (www.microchip.com) for the complete list of demonstration, development and evaluation kits. (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings() Ambient temperature under bias.............................................................................................................-40C to +125C Storage temperature .............................................................................................................................. -65C to +150C Voltage on any pin with respect to VSS (except VDD and MCLR) ................................................... -0.3V to (VDD + 0.3V) Voltage on VDD with respect to VSS ......................................................................................................... -0.3V to +7.5V Voltage on MCLR with respect to VSS (Note 2) ......................................................................................... 0V to +13.25V Total power dissipation (Note 1) ...............................................................................................................................1.0W Maximum current out of VSS pin ...........................................................................................................................300 mA Maximum current into VDD pin ..............................................................................................................................250 mA Input clamp current, IIK (VI < 0 or VI > VDD)...................................................................................................................... 20 mA Output clamp current, IOK (VO < 0 or VO > VDD) .............................................................................................................. 20 mA Maximum output current sunk by any I/O pin..........................................................................................................25 mA Maximum output current sourced by any I/O pin ....................................................................................................25 mA Maximum current sunk by all ports .......................................................................................................................200 mA Maximum current sourced by all ports ..................................................................................................................200 mA Note 1: Power dissipation is calculated as follows: Pdis = VDD x {IDD - IOH} + {(VDD - VOH) x IOH} + (VOL x IOL) 2: Voltage spikes below VSS at the MCLR/VPP/RE3 pin, inducing currents greater than 80 mA, may cause latch-up. Thus, a series resistor of 50-100 should be used when applying a "low" level to the MCLR/VPP/ RE3 pin, rather than pulling this pin directly to VSS. NOTICE: Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. (c) 2008 Microchip Technology Inc. DS39631E-page 321 PIC18F2420/2520/4420/4520 FIGURE 26-1: PIC18F2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL) 6.0V 5.5V Voltage 5.0V PIC18F2420/2520/4420/4520 4.5V 4.2V 4.0V 3.5V 3.0V 2.5V 2.0V 40 MHz Frequency FIGURE 26-2: PIC18F2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (EXTENDED) 6.0V 5.5V Voltage 5.0V PIC18F2420/2520/4420/4520 4.5V 4.2V 4.0V 3.5V 3.0V 2.5V 2.0V 25 MHz Frequency DS39631E-page 322 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-3: PIC18LF2420/2520/4420/4520 VOLTAGE-FREQUENCY GRAPH (INDUSTRIAL) 6.0V 5.5V Voltage 5.0V 4.5V PIC18LF2420/2520/4420/4520 4.2V 4.0V 3.5V 3.0V 2.5V 2.0V 40 MHz 4 MHz Frequency FMAX = (16.36 MHz/V) (VDDAPPMIN - 2.0V) + 4 MHz Note: VDDAPPMIN is the minimum voltage of the PIC(R) device in the application. (c) 2008 Microchip Technology Inc. DS39631E-page 323 PIC18F2420/2520/4420/4520 26.1 DC Characteristics: Supply Voltage PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. D001 Symbol VDD Characteristic Min Typ Max Units Conditions Supply Voltage PIC18LF2X2X/4X20 2.0 -- 5.5 V HS, XT, RC and LP Oscillator mode PIC18F2X20/4X20 4.2 -- 5.5 V D002 VDR RAM Data Retention 1.5 -- -- V Voltage(1) VDD Start Voltage -- -- 0.7 V See section on Power-on Reset for details D003 VPOR to Ensure Internal Power-on Reset Signal D004 SVDD VDD Rise Rate 0.05 -- -- V/ms See section on Power-on Reset for details to Ensure Internal Power-on Reset Signal VBOR Brown-out Reset Voltage D005 PIC18LF2X2X/4X20 BORV<1:0> = 11 2.00 2.11 2.22 V BORV<1:0> = 10 2.65 2.79 2.93 V D005 All Devices BORV<1:0> = 01(2) 4.11 4.33 4.55 V BORV<1:0> = 00 4.36 4.59 4.82 V Legend: Shading of rows is to assist in readability of the table. Note 1: This is the limit to which VDD can be lowered in Sleep mode, or during a device Reset, without losing RAM data. 2: With BOR enabled, full-speed operation (FOSC = 40 MHz) is supported until a BOR occurs. This is valid although VDD may be below the minimum voltage for this frequency. DS39631E-page 324 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units Power-Down Current (IPD)(1) PIC18LF2X2X/4X20 0.1 0.1 0.5 0.5 A A -40C +25C 0.2 0.1 0.1 0.3 0.1 2.5 0.7 0.7 3.5 1.0 A A A A A +85C -40C +25C +85C -40C PIC18LF2X2X/4X20 All devices Legend: Note 1: 2: 3: 4: Conditions VDD = 2.0V (Sleep mode) VDD = 3.0V (Sleep mode) 0.2 1.0 A +25C VDD = 5.0V (Sleep mode) 0.7 10 A +85C Extended devices only 10 100 A +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. (c) 2008 Microchip Technology Inc. DS39631E-page 325 PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units 13 13 14 42 34 28 103 82 67 71 320 25 22 25 61 46 45 160 130 120 230 440 A A A A A A A A A A A Conditions Supply Current (IDD)(2) PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only PIC18LF2X2X/4X20 Legend: Note 1: 2: 3: 4: -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C VDD = 2.0V VDD = 3.0V FOSC = 31 kHz (RC_RUN mode, INTRC source) VDD = 5.0V VDD = 2.0V 330 440 A +25C 330 440 A +85C PIC18LF2X2X/4X20 630 800 A -40C FOSC = 1 MHz 590 720 A +25C VDD = 3.0V (RC_RUN mode, 570 700 A +85C INTOSC source) All devices 1.2 1.6 mA -40C 1.0 1.5 mA +25C VDD = 5.0V 1.0 1.5 mA +85C Extended devices only 1.0 1.5 mA +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. DS39631E-page 326 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units Conditions Supply Current (IDD)(2) PIC18LF2X2X/4X20 Legend: Note 1: 2: 3: 4: 0.8 1.1 mA -40C 0.8 1.1 mA +25C VDD = 2.0V 0.8 1.1 mA +85C PIC18LF2X2X/4X20 1.3 1.7 mA -40C FOSC = 4 MHz VDD = 3.0V 1.3 1.7 mA +25C (RC_RUN mode, 1.3 1.7 mA +85C INTOSC source) All devices 2.5 3.5 mA -40C 2.5 3.5 mA +25C VDD = 5.0V 2.5 3.5 mA +85C Extended devices only 2.5 3.5 mA +125C PIC18LF2X2X/4X20 2.9 5 A -40C VDD = 2.0V 3.1 5 A +25C 3.6 9.5 A +85C PIC18LF2X2X/4X20 4.5 8 A -40C FOSC = 31 kHz 4.8 8 A +25C VDD = 3.0V (RC_IDLE mode, 5.8 15 A +85C INTRC source) All devices 9.2 16 A -40C 9.8 16 A +25C VDD = 5.0V 11.0 35 A +85C Extended devices only 21 160 A +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. (c) 2008 Microchip Technology Inc. DS39631E-page 327 PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Supply Current (IDD)(2) PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only Legend: Note 1: 2: 3: 4: Typ Max Units 165 175 190 250 270 290 500 520 550 0.6 340 350 360 520 540 580 1.0 1.1 1.1 1.1 250 250 270 360 360 380 700 700 700 1 500 500 500 800 800 850 1.6 1.4 1.4 2.0 A A A A A A A A A mA A A A A A A mA mA mA mA Conditions -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C VDD = 2.0V VDD = 3.0V FOSC = 1 MHz (RC_IDLE mode, INTOSC source) VDD = 5.0V VDD = 2.0V VDD = 3.0V FOSC = 4 MHz (RC_IDLE mode, INTOSC source) VDD = 5.0V Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. DS39631E-page 328 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units Conditions 250 260 250 550 480 460 1.2 1.1 1.0 1.0 0.72 350 350 350 650 640 600 1.5 1.4 1.3 3.0 1.0 A A A A A A mA mA mA mA mA -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C 0.74 0.74 1.3 1.3 1.3 2.7 2.6 2.5 2.6 8.4 11 1.0 1.0 1.8 1.8 1.8 4.0 4.0 4.0 5.0 13 16 mA mA mA mA mA mA mA mA mA mA mA +25C +85C -40C +25C +85C -40C +25C +85C +125C +125C +125C Supply Current (IDD)(2) PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only Extended devices only VDD = 2.0V VDD = 3.0V FOSC = 1 MHZ (PRI_RUN, EC oscillator) VDD = 5.0V VDD = 2.0V VDD = 3.0V FOSC = 4 MHz (PRI_RUN, EC oscillator) VDD = 5.0V VDD = 4.2V VDD = 5.0V FOSC = 25 MHz (PRI_RUN, EC oscillator) All devices Legend: Note 1: 2: 3: 4: 15 20 mA -40C VDD = 4.2V 15 20 mA +25C FOSC = 40 MHZ 15 20 mA +85C (PRI_RUN, All devices 20 25 mA -40C EC oscillator) 20 25 mA +25C VDD = 5.0V 20 25 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. (c) 2008 Microchip Technology Inc. DS39631E-page 329 PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units 7.5 7.4 7.3 8.0 10 10 10 10 12 12 mA mA mA mA mA Conditions Supply Current (IDD)(2) All devices Extended devices only All devices Legend: Note 1: 2: 3: 4: -40C +25C +85C +125C -40C VDD = 4.2V FOSC = 4 MHZ, 16 MHz internal (PRI_RUN HS+PLL) FOSC = 4 MHZ, 10 12 mA +25C 16 MHz internal VDD = 5.0V 9.7 12 mA +85C (PRI_RUN HS+PLL) Extended devices only 10 14 mA +125C All devices 15 20 mA -40C FOSC = 10 MHZ, VDD = 4.2V 15 20 mA +25C 40 MHz internal (PRI_RUN HS+PLL) 15 20 mA +85C All devices 20 25 mA -40C FOSC = 10 MHZ, 20 25 mA +25C 40 MHz internal VDD = 5.0V (PRI_RUN HS+PLL) 20 25 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. DS39631E-page 330 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Supply Current (IDD)(2) PIC18LF2X2X/4X20 65 100 A -40C 65 70 120 120 130 230 235 240 260 260 255 270 420 430 450 0.9 0.9 0.9 1 2.8 4.3 100 110 140 140 160 300 300 300 500 360 360 360 620 620 650 1.2 1.2 1.2 1.3 6.0 8.0 A A A A A A A A A A A A A A A mA mA mA mA mA mA +25C +85C -40C +25C +85C -40C +25C +85C +125C -40C +25C +85C -40C +25C +85C -40C +25C +85C +125C +125C +125C 6.0 6.2 6.6 8.1 10 10 10 13 mA mA mA mA -40C +25C +85C -40C PIC18LF2X2X/4X20 All devices Extended devices only PIC18LF2X2X/4X20 PIC18LF2X2X/4X20 All devices Extended devices only Extended devices only All devices All devices Legend: Note 1: 2: 3: 4: Units Conditions VDD = 2.0V VDD = 3.0V FOSC = 1 MHz (PRI_IDLE mode, EC oscillator) VDD = 5.0V VDD = 2.0V VDD = 3.0V FOSC = 4 MHz (PRI_IDLE mode, EC oscillator) VDD = 5.0V VDD = 4.2V VDD = 5.0V VDD = 4.2V FOSC = 25 MHz (PRI_IDLE mode, EC oscillator) FOSC = 40 MHz (PRI_IDLE mode, EC oscillator) VDD = 5.0V 9.1 12 mA +25C 8.3 12 mA +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. (c) 2008 Microchip Technology Inc. DS39631E-page 331 PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Supply Current (IDD)(2) PIC18LF2X2X/4X20 Legend: Note 1: 2: 3: 4: Typ Max Units 10 11 25 21 A A Conditions -40C(3) +25C VDD = 2.0V 12 25 A +85C PIC18LF2X2X/4X20 42 57 A -40C(3) FOSC = 32 kHz(3) 33 45 A +25C VDD = 3.0V (SEC_RUN mode, Timer1 as clock) 29 45 A +85C (3) All devices 105 150 A -40C 81 130 A +25C VDD = 5.0V 67 130 A +85C PIC18LF2X2X/4X20 3.0 12 A -40C(3) 3.0 6 A +25C VDD = 2.0V 3.7 10 A +85C PIC18LF2X2X/4X20 5.0 15 A -40C(3) FOSC = 32 kHz(3) 5.4 10 A +25C VDD = 3.0V (SEC_IDLE mode, Timer1 as clock) 6.3 15 A +85C (3) All devices 8.5 25 A -40C 9.0 20 A +25C VDD = 5.0V 10.5 30 A +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. DS39631E-page 332 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device Typ Max Units Conditions Module Differential Currents (IWDT, IBOR, ILVD, IOSCB, IAD) A/D Converter 0.2 1.0 A -40C to +85C 0.2 1.0 A -40C to +85C 0.2 1.0 A -40C to +85C D026 (IAD) D022 (IWDT) D022A (IBOR) D022B (ILVD) Legend: Note 1: 2: 3: 4: Watchdog Timer 0.5 1.3 1.4 1.6 1.9 4.0 2.2 2.2 2.3 3.5 A A A A A -40C to +125C -40C +25C +85C -40C 2.0 2.2 3.0 3.5 3.5 4.0 3.5 3.5 7.5 7.5 7.8 10 A A A A A A +25C +85C -40C +25C +85C +125C VDD = 2.0V VDD = 3.0V A/D on, not converting VDD = 5.0V VDD = 2.0V VDD = 3.0V VDD = 5.0V Brown-out Reset(4) 35 50 A -40C to +85C VDD = 3.0V 40 55 A -40C to +85C 55 65 A -40C to +125C VDD = 5.0V 0 2 A -40C to +85C Sleep mode, BOREN<1:0> = 10 0 5 A -40C to +125C 38 A -40C to +85C VDD = 2.0V High/Low-Voltage 22 Detect(4) 25 40 A -40C to +85C VDD = 3.0V 29 45 A -40C to +85C VDD = 5.0V 30 45 A -40C to +125C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. (c) 2008 Microchip Technology Inc. DS39631E-page 333 PIC18F2420/2520/4420/4520 26.2 DC Characteristics: Power-Down and Supply Current PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial, Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial -40C TA +125C for extended Param No. Device D025L (IOSCB) Legend: Note 1: 2: 3: 4: Timer1 Oscillator Typ Max Units 4.5 0.9 0.9 9.0 1.6 1.6 A A A Conditions -40C(3) -10C +25C VDD = 2.0V 32 kHz on Timer1 0.9 1.8 A +85C 4.8 10 A -40C(3) 1.0 2.0 A -10C VDD = 3.0V 32 kHz on Timer1 1.0 2.0 A +25C 1.0 2.6 A +85C 6.0 11 A -40C(3) 1.6 4.0 A -10C VDD = 5.0V 32 kHz on Timer1 1.6 4.0 A +25C 1.6 4.0 A +85C Shading of rows is to assist in readability of the table. The power-down current in Sleep mode does not depend on the oscillator type. Power-down current is measured with the part in Sleep mode, with all I/O pins in high-impedance state and tied to VDD or VSS and all features that add delta current disabled (such as WDT, Timer1 Oscillator, BOR, etc.). The supply current is mainly a function of operating voltage, frequency and mode. Other factors, such as I/O pin loading and switching rate, oscillator type and circuit, internal code execution pattern and temperature, also have an impact on the current consumption. The test conditions for all IDD measurements in active operation mode are: OSC1 = external square wave, from rail-to-rail; all I/O pins tri-stated, pulled to VDD or VSS; MCLR = VDD; WDT enabled/disabled as specified. When operation below -10C is expected, use T1OSC High-Power mode, where LPT1OSC (CONFIG3H<2>) = 0. When operation will always be above -10C, then the low-power Timer1 oscillator may be selected. BOR and HLVD enable internal band gap reference. With both modules enabled, current consumption will be less than the sum of both specifications. DS39631E-page 334 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.3 DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial DC CHARACTERISTICS Param Symbol No. VIL Characteristic Min Max Units Conditions VSS 0.15 VDD V VDD < 4.5V -- 0.8 V 4.5V VDD 5.5V VSS 0.2 VDD V VSS 0.3 VDD V I2CTM enabled SMBus enabled Input Low Voltage I/O Ports: D030 with TTL Buffer D030A D031 with Schmitt Trigger Buffer D031A RC3 and RC4 VSS 0.8 V D032 MCLR VSS 0.2 VDD V D033 OSC1 VSS 0.3 VDD V HS, HSPLL modes D033A D033B D034 OSC1 OSC1 T13CKI VSS VSS VSS 0.2 VDD 0.3 0.3 V V V RC, EC modes(1) XT, LP modes 0.25 VDD + 0.8V VDD V VDD < 4.5V 2.0 VDD V 4.5V VDD 5.5V 0.8 VDD VDD V 0.7 VDD VDD V I2C enabled 2.1 VDD V SMBus enabled VDD V D031B VIH Input High Voltage I/O Ports: D040 with TTL Buffer D040A D041 with Schmitt Trigger Buffer D041A RC3 and RC4 D041B D042 MCLR 0.8 VDD D043 OSC1 0.7 VDD VDD V HS, HSPLL modes D043A D043B D043C D044 OSC1 OSC1 OSC1 T13CKI 0.8 VDD 0.9 VDD 1.6 1.6 VDD VDD VDD VDD V V V V EC mode RC mode(1) XT, LP modes -- 200 nA 50 nA VDD < 5.5V, VSS VPIN VDD, Pin at high-impedance VDD < 3V, VSS VPIN VDD, Pin at high-impedance IIL D060 Input Leakage Current(2,3) I/O Ports D061 D063 D070 Note 1: 2: 3: MCLR -- 1 A Vss VPIN VDD OSC1 -- 1 A Vss VPIN VDD 50 400 A VDD = 5V, VPIN = VSS IPU Weak Pull-up Current IPURB PORTB Weak Pull-up Current In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the PIC(R) device be driven with an external clock while in RC mode. 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. Negative current is defined as current sourced by the pin. (c) 2008 Microchip Technology Inc. DS39631E-page 335 PIC18F2420/2520/4420/4520 26.3 DC Characteristics: PIC18F2420/2520/4420/4520 (Industrial) PIC18LF2420/2520/4420/4520 (Industrial) (Continued) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial DC CHARACTERISTICS Param Symbol No. VOL Characteristic Min Max Units Conditions Output Low Voltage D080 I/O Ports -- 0.6 V IOL = 8.5 mA, VDD = 4.5V, -40C to +85C D083 OSC2/CLKO (RC, RCIO, EC, ECIO modes) -- 0.6 V IOL = 1.6 mA, VDD = 4.5V, -40C to +85C VOH Output High Voltage(3) D090 I/O Ports VDD - 0.7 -- V IOH = -3.0 mA, VDD = 4.5V, -40C to +85C D092 OSC2/CLKO (RC, RCIO, EC, ECIO modes) VDD - 0.7 -- V IOH = -1.3 mA, VDD = 4.5V, -40C to +85C -- 15 pF In XT, HS and LP modes when external clock is used to drive OSC1 Capacitive Loading Specs on Output Pins D100 COSC2 OSC2 pin D101 CIO All I/O pins and OSC2 (in RC mode) -- 50 pF To meet the AC Timing Specifications D102 CB SCL, SDA -- 400 pF I2CTM Specification Note 1: 2: 3: In RC oscillator configuration, the OSC1/CLKI pin is a Schmitt Trigger input. It is not recommended that the PIC(R) device be driven with an external clock while in RC mode. 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. Negative current is defined as current sourced by the pin. DS39631E-page 336 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 26-1: MEMORY PROGRAMMING REQUIREMENTS Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial DC CHARACTERISTICS Param No. Sym Characteristic Min Typ Max Units Conditions Data EEPROM Memory D120 ED Byte Endurance 100K 1M -- D121 VDRW VDD for Read/Write VMIN -- 5.5 E/W -40C to +85C V D122 TDEW Erase/Write Cycle Time -- 4 -- ms D123 TRETD Characteristic Retention 40 -- -- Year Provided no other specifications are violated D124 TREF Number of Total Erase/Write Cycles before Refresh(1) 1M 10M -- E/W -40C to +85C D125 IDDP Supply Current during Programming -- 10 -- mA E/W -40C to +85C Using EECON to read/write VMIN = Minimum operating voltage Program Flash Memory D130 EP Cell Endurance 10K 100K -- D131 VPR VDD for Read VMIN -- 5.5 V D132 VIE VDD for Block Erase 3.0 -- 5.5 V Using ICSPTM port, +25C D132A VIW VDD for Externally Timed Erase or Write 4.5 -- 5.5 V Using ICSPTM port, +25C D132B VPEW VDD for Self-Timed Write VMIN -- 5.5 V VMIN = Minimum operating voltage D133 ICSP Block Erase Cycle Time -- 4 -- ms VDD 4.5V D133A TIW ICSP Erase or Write Cycle Time (externally timed) 1 -- -- ms VDD 4.5V, +25C D133A TIW Self-Timed Write Cycle Time -- 2 -- ms 40 100 -- Year Provided no other specifications are violated -- 10 -- mA TIE D134 TRETD Characteristic Retention D135 IDDP Supply Current during Programming VMIN = Minimum operating voltage Data in "Typ" column is at 5.0V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Refer to Section 7.8 "Using the Data EEPROM" for a more detailed discussion on data EEPROM endurance. (c) 2008 Microchip Technology Inc. DS39631E-page 337 PIC18F2420/2520/4420/4520 TABLE 26-2: COMPARATOR SPECIFICATIONS Operating Conditions: 3.0V < VDD < 5.5V, -40C < TA < +85C (unless otherwise stated). Param No. Sym Characteristics Min Typ Max Units Comments D300 VIOFF Input Offset Voltage -- 5.0 10 mV D301 VICM Input Common Mode Voltage 0 -- VDD - 1.5 V D302 CMRR Common Mode Rejection Ratio 55 -- -- dB 300 TRESP Response Time(1) -- 150 400 ns PIC18FXXXX -- 150 600 ns PIC18LFXXXX, VDD = 2.0V -- -- 10 s 300A 301 Note 1: TMC2OV Comparator Mode Change to Output Valid Response time measured with one comparator input at (VDD - 1.5)/2, while the other input transitions from VSS to VDD. TABLE 26-3: VOLTAGE REFERENCE SPECIFICATIONS Operating Conditions: 3.0V < VDD < 5.5V, -40C < TA < +85C (unless otherwise stated). Param No. Sym Characteristics Min Typ Max Units VDD/24 -- VDD/32 LSb VRES Resolution D311 VRAA Absolute Accuracy -- -- 1/2 LSb D312 VRUR Unit Resistor Value (R) -- 2k -- TSET Time(1) -- -- 10 s D310 310 Note 1: Settling Comments Settling time measured while CVRR = 1 and CVR3:CVR0 transitions from `0000' to `1111'. DS39631E-page 338 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-4: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS VDD (HLVDIF can be cleared in software) VLVD (HLVDIF set by hardware) HLVDIF(1) Note 1: VDIRMAG = 0. TABLE 26-4: HIGH/LOW-VOLTAGE DETECT CHARACTERISTICS Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Param Sym No. D420 Characteristic Min Typ Max Units HLVD Voltage on VDD HLVDL<3:0> = 0000 Transition High-to-Low HLVDL<3:0> = 0001 2.06 2.17 2.28 V 2.12 2.23 2.34 V HLVDL<3:0> = 0010 2.24 2.36 2.48 V HLVDL<3:0> = 0011 2.32 2.44 2.56 V HLVDL<3:0> = 0100 2.47 2.60 2.73 V HLVDL<3:0> = 0101 2.65 2.79 2.93 V HLVDL<3:0> = 0110 2.74 2.89 3.04 V HLVDL<3:0> = 0111 2.96 3.12 3.28 V HLVDL<3:0> = 1000 3.22 3.39 3.56 V HLVDL<3:0> = 1001 3.37 3.55 3.73 V HLVDL<3:0> = 1010 3.52 3.71 3.90 V HLVDL<3:0> = 1011 3.70 3.90 4.10 V HLVDL<3:0> = 1100 3.90 4.11 4.32 V HLVDL<3:0> = 1101 4.11 4.33 4.55 V HLVDL<3:0> = 1110 4.36 4.59 4.82 V (c) 2008 Microchip Technology Inc. Conditions DS39631E-page 339 PIC18F2420/2520/4420/4520 26.4 26.4.1 AC (Timing) Characteristics TIMING PARAMETER SYMBOLOGY The timing parameter symbols have been created using one of the following formats: 1. TppS2ppS 2. TppS T F Frequency Lowercase letters (pp) and their meanings: pp cc CCP1 ck CLKO cs CS di SDI do SDO dt Data in io I/O port mc MCLR Uppercase letters and their meanings: S F Fall H High I Invalid (High-impedance) L Low I2C only AA output access BUF Bus free 2 TCC:ST (I C specifications only) CC HD Hold ST DAT DATA input hold STA Start condition DS39631E-page 340 3. TCC:ST 4. Ts (I2C specifications only) (I2C specifications only) T Time osc rd rw sc ss t0 t1 wr OSC1 RD RD or WR SCK SS T0CKI T13CKI WR P R V Z Period Rise Valid High-impedance High Low High Low SU Setup STO Stop condition (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 26.4.2 TIMING CONDITIONS Note: The temperature and voltages specified in Table 26-5 apply to all timing specifications unless otherwise noted. Figure 26-5 specifies the load conditions for the timing specifications. TABLE 26-5: TEMPERATURE AND VOLTAGE SPECIFICATIONS - AC AC CHARACTERISTICS FIGURE 26-5: Because of space limitations, the generic terms "PIC18FXXXX" and "PIC18LFXXXX" are used throughout this section to refer to the PIC18F2420/2520/4420/4520 and PIC18LF2420/2520/4420/4520 families of devices specifically and only those devices. Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Operating voltage VDD range as described in DC specification Section 26.1 and Section 26.3. LF parts operate for industrial temperatures only. LOAD CONDITIONS FOR DEVICE TIMING SPECIFICATIONS Load Condition 2 Load Condition 1 VDD/2 RL CL Pin VSS CL Pin RL = 464 VSS (c) 2008 Microchip Technology Inc. CL = 50 pF for all pins except OSC2/CLKO and including D and E outputs as ports DS39631E-page 341 PIC18F2420/2520/4420/4520 26.4.3 TIMING DIAGRAMS AND SPECIFICATIONS FIGURE 26-6: EXTERNAL CLOCK TIMING (ALL MODES EXCEPT PLL) Q4 Q1 Q2 Q3 Q4 Q1 OSC1 1 3 4 3 4 2 CLKO TABLE 26-6: Param. No. 1A EXTERNAL CLOCK TIMING REQUIREMENTS Symbol FOSC Characteristic Min Max Units External CLKI Frequency(1) DC 1 MHz XT, RC Oscillator mode DC 25 MHz HS Oscillator mode DC 31.25 kHz LP Oscillator mode DC 40 MHz EC Oscillator mode DC 4 MHz RC Oscillator mode 0.1 4 MHz XT Oscillator mode 4 25 MHz HS Oscillator mode 4 10 MHz HS + PLL Oscillator mode LP Oscillator mode Oscillator Frequency 1 TOSC (1) External CLKI Period(1) Oscillator Period(1) 2 3 4 Note 1: TCY Instruction Cycle Time(1) TOSL, TOSH External Clock in (OSC1) High or Low Time TOSR, TOSF External Clock in (OSC1) Rise or Fall Time Conditions 5 200 kHz 1000 -- ns XT, RC Oscillator mode 40 -- ns HS Oscillator mode 32 -- s LP Oscillator mode 25 -- ns EC Oscillator mode 250 -- ns RC Oscillator mode 0.25 10 s XT Oscillator mode 40 250 ns HS Oscillator mode 100 250 ns HS + PLL Oscillator mode 5 200 s LP Oscillator mode 100 -- ns TCY = 4/FOSC, Industrial 160 -- ns TCY = 4/FOSC, Extended 30 -- ns XT Oscillator mode 2.5 -- s LP Oscillator mode 10 -- ns HS Oscillator mode -- 20 ns XT Oscillator mode -- 50 ns LP Oscillator mode -- 7.5 ns HS Oscillator mode Instruction cycle period (TCY) equals four times the input oscillator time base period for all configurations except PLL. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device executing code. Exceeding these specified limits may result in an unstable oscillator operation and/or higher than expected current consumption. All devices are tested to operate at "min." values with an external clock applied to the OSC1/CLKI pin. When an external clock input is used, the "max." cycle time limit is "DC" (no clock) for all devices. DS39631E-page 342 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 TABLE 26-7: Param No. PLL CLOCK TIMING SPECIFICATIONS (VDD = 4.2V TO 5.5V) Sym Characteristic Min Typ Max 4 16 -- -- 10 40 Units F10 F11 FOSC Oscillator Frequency Range FSYS On-Chip VCO System Frequency F12 trc PLL Start-up Time (Lock Time) -- -- 2 ms CLK CLKO Stability (Jitter) -2 -- +2 % F13 Conditions MHz HS mode only MHz HS mode only Data in "Typ" column is at 5V, 25C unless otherwise stated. These parameters are for design guidance only and are not tested. TABLE 26-8: AC CHARACTERISTICS: INTERNAL RC ACCURACY PIC18F2420/2520/4420/4520 (INDUSTRIAL) PIC18LF2420/2520/4420/4520 (INDUSTRIAL) PIC18LF2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial PIC18F2420/2520/4420/4520 (Industrial) Standard Operating Conditions (unless otherwise stated) Operating temperature -40C TA +85C for industrial Param No. Device Min Typ Max Units Conditions INTOSC Accuracy @ Freq = 8 MHz, 4 MHz, 2 MHz, 1 MHz, 500 kHz, 250 kHz, 125 kHz, 31 kHz(1) PIC18LF2420/2520/4420/4520 -2 +/-1 2 % -5 +/-1 5 % -2 +/-1 2 % -5 +/-1 5 % -40C to +85C VDD = 4.5-5.5V PIC18LF2420/2520/4420/4520 26.562 -- 35.938 kHz -40C to +85C VDD = 2.7-3.3V PIC18F2420/2520/4420/4520 26.562 -- 35.938 kHz -40C to +85C VDD = 4.5-5.5V PIC18F2420/2520/4420/4520 +25C VDD = 2.7-3.3V -40C to +85C VDD = 2.7-3.3V +25C VDD = 4.5-5.5V INTRC Accuracy @ Freq = 31 kHz Legend: Note 1: Shading of rows is to assist in readability of the table. Frequency calibrated at 25C. OSCTUNE register can be used to compensate for temperature drift. (c) 2008 Microchip Technology Inc. DS39631E-page 343 PIC18F2420/2520/4420/4520 FIGURE 26-7: CLKO AND I/O TIMING Q1 Q4 Q2 Q3 OSC1 11 10 CLKO 13 14 19 12 18 16 I/O pin (Input) 15 17 I/O pin (Output) Note: 20, 21 Refer to Figure 26-5 for load conditions. TABLE 26-9: Param No. 10 New Value Old Value CLKO AND I/O TIMING REQUIREMENTS Symbol Characteristic TosH2ckL OSC1 to CLKO Min Typ Max -- 75 200 Units Conditions ns (Note 1) 11 TosH2ckH OSC1 to CLKO -- 75 200 ns (Note 1) 12 TckR CLKO Rise Time -- 35 100 ns (Note 1) 13 TckF CLKO Fall Time -- 35 100 ns (Note 1) 14 TckL2ioV CLKO to Port Out Valid -- -- 0.5 TCY + 20 ns (Note 1) 15 TioV2ckH Port In Valid before CLKO 16 TckH2ioI 17 TosH2ioV OSC1 (Q1 cycle) to Port Out Valid 18 TosH2ioI 18A Port In Hold after CLKO OSC1 (Q2 cycle) to Port Input Invalid (I/O in hold time) 0.25 TCY + 25 -- -- ns (Note 1) 0 -- -- ns (Note 1) -- 50 150 ns PIC18FXXXX 100 -- -- ns PIC18LFXXXX 200 -- -- ns 19 TioV2osH Port Input Valid to OSC1 (I/O in setup time) 0 -- -- ns 20 TioR Port Output Rise Time -- 10 25 ns TioF Port Output Fall Time 22 TINP INTx pin High or Low Time 23 TRBP RB<7:4> Change INTx High or Low Time TCY 20A 21 21A PIC18FXXXX PIC18LFXXXX -- -- 60 ns PIC18FXXXX -- 10 25 ns -- -- 60 ns TCY -- -- ns -- -- ns PIC18LFXXXX VDD = 2.0V VDD = 2.0V VDD = 2.0V These parameters are asynchronous events not related to any internal clock edges. Note 1: Measurements are taken in RC mode, where CLKO output is 4 x TOSC. DS39631E-page 344 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-8: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER AND POWER-UP TIMER TIMING VDD MCLR 30 Internal POR 33 PWRT Time-out 32 OSC Time-out Internal Reset Watchdog Timer Reset 31 34 34 I/O pins Note: Refer to Figure 26-5 for load conditions. FIGURE 26-9: BROWN-OUT RESET TIMING BVDD VDD 35 VIRVST Enable Internal Reference Voltage Internal Reference Voltage Stable 36 TABLE 26-10: RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER AND BROWN-OUT RESET REQUIREMENTS Param. Symbol No. Characteristic Min Typ Max Units 2 3.4 -- 4.1 -- 4.71 s ms 1024 TOSC -- 1024 TOSC -- 55.6 65.5 75.4 ms -- 2 -- s Conditions 30 31 TmcL TWDT 32 TOST MCLR Pulse Width (low) Watchdog Timer Time-out Period (no postscaler) Oscillation Start-up Timer Period 33 TPWRT Power-up Timer Period 34 TIOZ I/O High-Impedance from MCLR Low or Watchdog Timer Reset 35 36 TBOR TIRVST Brown-out Reset Pulse Width Time for Internal Reference Voltage to become Stable 200 -- -- 20 -- 50 s s VDD BVDD (see D005) 37 38 TLVD TCSD High/Low-Voltage Detect Pulse Width CPU Start-up Time 200 -- -- 10 -- -- s s VDD VLVD 39 TIOBST Time for INTOSC to Stabilize -- 1 -- s (c) 2008 Microchip Technology Inc. TOSC = OSC1 period DS39631E-page 345 PIC18F2420/2520/4420/4520 FIGURE 26-10: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS T0CKI 41 40 42 T1OSO/T13CKI 46 45 47 48 TMR0 or TMR1 Note: Refer to Figure 26-5 for load conditions. TABLE 26-11: TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS Param No. Symbol Characteristic 40 Tt0H T0CKI High Pulse Width 41 Tt0L T0CKI Low Pulse Width 42 Tt0P T0CKI Period No prescaler With prescaler No prescaler With prescaler 45 Tt1H 47 -- ns 10 -- ns 0.5 TCY + 20 -- ns ns -- ns With prescaler Greater of: 20 ns or (TCY + 40)/N -- ns T13CKI Synchronous, no prescaler High Time Synchronous, PIC18FXXXX with prescaler PIC18LFXXXX 0.5 TCY + 20 -- ns 10 -- ns 25 -- ns 30 -- ns PIC18FXXXX T13CKI Low Time Synchronous, no prescaler 50 -- ns 0.5 TCY + 5 -- ns N = prescale value (1, 2, 4,..., 256) VDD = 2.0V VDD = 2.0V Synchronous, with prescaler PIC18FXXXX 10 -- ns PIC18LFXXXX 25 -- ns Asynchronous PIC18FXXXX 30 -- ns PIC18LFXXXX 50 -- ns VDD = 2.0V Greater of: 20 ns or (TCY + 40)/N -- ns N = prescale value (1, 2, 4, 8) Tt1P T13CKI Input Period Ft1 T13CKI Oscillator Input Frequency Range Synchronous Tcke2tmrI Delay from External T13CKI Clock Edge to Timer Increment DS39631E-page 346 0.5 TCY + 20 -- Asynchronous 48 Units Conditions 10 No prescaler PIC18LFXXXX Tt1L Max TCY + 10 Asynchronous 46 Min 60 -- ns DC 50 kHz 2 TOSC 7 TOSC -- VDD = 2.0V (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-11: CAPTURE/COMPARE/PWM TIMINGS (ALL CCP MODULES) CCPx (Capture Mode) 50 51 52 CCPx (Compare or PWM Mode) 53 Note: 54 Refer to Figure 26-5 for load conditions. TABLE 26-12: CAPTURE/COMPARE/PWM REQUIREMENTS (ALL CCP MODULES) Param Symbol No. 50 51 TccL TccH Characteristic Min Max Units CCPx Input Low No prescaler Time With PIC18FXXXX prescaler PIC18LFXXXX 0.5 TCY + 20 -- ns 10 -- ns 20 -- ns CCPx Input High Time 0.5 TCY + 20 -- ns No prescaler With prescaler 52 TccP CCPx Input Period 53 TccR CCPx Output Fall Time 54 TccF CCPx Output Fall Time (c) 2008 Microchip Technology Inc. Conditions VDD = 2.0V PIC18FXXXX 10 -- ns PIC18LFXXXX 20 -- ns VDD = 2.0V 3 TCY + 40 N -- ns N = prescale value (1, 4 or 16) PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns VDD = 2.0V VDD = 2.0V DS39631E-page 347 PIC18F2420/2520/4420/4520 FIGURE 26-12: PARALLEL SLAVE PORT TIMING (PIC18F4420/4520) RE2/CS RE0/RD RE1/WR 65 RD<7:0> 62 64 63 Note: Refer to Figure 26-5 for load conditions. TABLE 26-13: PARALLEL SLAVE PORT REQUIREMENTS (PIC18F4420, PIC18F4520) Param. No. Symbol Characteristic 62 TdtV2wrH Data In Valid before WR or CS (setup time) 63 TwrH2dtI WR or CS to Data-In Invalid (hold time) Min Max Units 20 -- ns PIC18FXXXX 20 -- ns PIC18LFXXXX 35 -- ns 80 ns ns TrdL2dtV RD and CS to Data-Out Valid -- 65 TrdH2dtI RD or CS to Data-Out Invalid 10 30 66 TibfINH Inhibit of the IBF Flag bit being Cleared from WR or CS -- 3 TCY 64 DS39631E-page 348 Conditions VDD = 2.0V (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-13: EXAMPLE SPI MASTER MODE TIMING (CKE = 0) SS 70 SCK (CKP = 0) 71 72 78 79 79 78 SCK (CKP = 1) 80 bit 6 - - - - - -1 MSb SDO LSb 75, 76 SDI MSb In bit 6 - - - -1 LSb In 74 73 Note: Refer to Figure 26-5 for load conditions. TABLE 26-14: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 0) Param No. Symbol Characteristic Min Max Units 70 TssL2scH, TssL2scL SS to SCK or SCK Input TCY -- ns 73 TdiV2scH, TdiV2scL Setup Time of SDI Data Input to SCK Edge 20 -- ns 73A Tb2b Last Clock Edge of Byte 1 to the 1st Clock Edge of Byte 2 1.5 TCY + 40 -- ns 74 TscH2diL, TscL2diL Hold Time of SDI Data Input to SCK Edge 40 -- ns 75 TdoR SDO Data Output Rise Time -- 25 ns 76 TdoF SDO Data Output Fall Time 78 TscR SCK Output Rise Time (Master mode) PIC18FXXXX PIC18LFXXXX -- 45 ns -- 25 ns PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns 79 TscF SCK Output Fall Time (Master mode) -- 25 ns 80 TscH2doV, TscL2doV SDO Data Output Valid after SCK Edge PIC18FXXXX -- 50 ns PIC18LFXXXX -- 100 ns Note 1: 2: Conditions (Note 2) VDD = 2.0V VDD = 2.0V VDD = 2.0V Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. (c) 2008 Microchip Technology Inc. DS39631E-page 349 PIC18F2420/2520/4420/4520 FIGURE 26-14: EXAMPLE SPI MASTER MODE TIMING (CKE = 1) SS 81 SCK (CKP = 0) 71 72 79 73 SCK (CKP = 1) 80 78 MSb SDO bit 6 - - - - - -1 LSb bit 6 - - - -1 LSb In 75, 76 SDI MSb In 74 Note: Refer to Figure 26-5 for load conditions. TABLE 26-15: EXAMPLE SPI MODE REQUIREMENTS (MASTER MODE, CKE = 1) Param. No. Symbol Characteristic 73 TdiV2scH, TdiV2scL Setup Time of SDI Data Input to SCK Edge 73A Tb2b Last Clock Edge of Byte 1 to the 1st Clock Edge of Byte 2 74 TscH2diL, TscL2diL 75 TdoR Min Max Units 20 -- ns 1.5 TCY + 40 -- ns Hold Time of SDI Data Input to SCK Edge 40 -- ns SDO Data Output Rise Time PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns -- 25 ns PIC18FXXXX -- 25 ns PIC18LFXXXX 76 TdoF SDO Data Output Fall Time 78 TscR SCK Output Rise Time (Master mode) -- 45 ns 79 TscF SCK Output Fall Time (Master mode) -- 25 ns 80 TscH2doV, TscL2doV SDO Data Output Valid after SCK Edge PIC18FXXXX -- 50 ns PIC18LFXXXX -- 100 ns TdoV2scH, TdoV2scL SDO Data Output Setup to SCK Edge TCY -- ns 81 Note 1: 2: Conditions (Note 2) VDD = 2.0V VDD = 2.0V VDD = 2.0V Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. DS39631E-page 350 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-15: EXAMPLE SPI SLAVE MODE TIMING (CKE = 0) SS 70 SCK (CKP = 0) 83 71 72 78 79 79 78 SCK (CKP = 1) 80 MSb SDO bit 6 - - - - - -1 LSb 77 75, 76 MSb In SDI bit 6 - - - -1 LSb In 74 73 Refer to Figure 26-5 for load conditions. Note: TABLE 26-16: EXAMPLE SPI MODE REQUIREMENTS (SLAVE MODE TIMING, CKE = 0) Param No. Symbol Characteristic 70 TssL2scH, SS to SCK or SCK Input TssL2scL 71 TscH 71A 72 TscL 72A Min 3 TCY Max Units Conditions -- ns SCK Input High Time (Slave mode) Continuous 1.25 TCY + 30 -- ns Single Byte 40 -- ns SCK Input Low Time (Slave mode) Continuous 1.25 TCY + 30 -- ns Single Byte 40 -- ns 20 -- ns 73 TdiV2scH, Setup Time of SDI Data Input to SCK Edge TdiV2scL 73A Tb2b -- ns 74 TscH2diL, Hold Time of SDI Data Input to SCK Edge TscL2diL 40 -- ns 75 TdoR PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40 SDO Data Output Rise Time 76 TdoF -- 25 ns 77 TssH2doZ SS to SDO Output High-Impedance 10 50 ns 80 TscH2doV, SDO Data Output Valid after SCK Edge PIC18FXXXX TscL2doV PIC18LFXXXX -- 50 ns -- 100 ns 1.5 TCY + 40 -- ns 83 Note 1: 2: SDO Data Output Fall Time TscH2ssH, SS after SCK edge TscL2ssH (Note 1) (Note 1) (Note 2) VDD = 2.0V VDD = 2.0V Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. (c) 2008 Microchip Technology Inc. DS39631E-page 351 PIC18F2420/2520/4420/4520 FIGURE 26-16: EXAMPLE SPI SLAVE MODE TIMING (CKE = 1) 82 SS SCK (CKP = 0) 70 83 71 72 SCK (CKP = 1) 80 MSb SDO bit 6 - - - - - -1 LSb 75, 76 SDI MSb In Note: 77 bit 6 - - - -1 LSb In 74 Refer to Figure 26-5 for load conditions. TABLE 26-17: EXAMPLE SPI SLAVE MODE REQUIREMENTS (CKE = 1) Param No. Symbol Characteristic 70 TssL2scH, SS to SCK or SCK Input TssL2scL 71 TscH 71A 72 TscL 72A Min Max Units Conditions 3 TCY -- ns SCK Input High Time (Slave mode) Continuous 1.25 TCY + 30 -- ns Single Byte 40 -- ns SCK Input Low Time (Slave mode) Continuous 1.25 TCY + 30 -- ns Single Byte 40 -- ns (Note 1) -- ns (Note 2) -- ns Last Clock Edge of Byte 1 to the First Clock Edge of Byte 2 1.5 TCY + 40 73A Tb2b 74 TscH2diL, Hold Time of SDI Data Input to SCK Edge TscL2diL 75 TdoR SDO Data Output Rise Time 40 PIC18FXXXX -- 25 ns PIC18LFXXXX -- 45 ns 76 TdoF -- 25 ns 77 TssH2doZ SS to SDO Output High-Impedance 10 50 ns 80 TscH2doV, SDO Data Output Valid after SCK TscL2doV Edge PIC18FXXXX -- 50 ns PIC18LFXXXX -- 100 ns 82 TssL2doV SDO Data Output Valid after SS Edge PIC18FXXXX -- 50 ns -- 100 ns 83 TscH2ssH, SS after SCK Edge TscL2ssH 1.5 TCY + 40 -- ns Note 1: 2: SDO Data Output Fall Time PIC18LFXXXX (Note 1) VDD = 2.0V VDD = 2.0V VDD = 2.0V Requires the use of Parameter #73A. Only if Parameter #71A and #72A are used. DS39631E-page 352 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 I2CTM BUS START/STOP BITS TIMING FIGURE 26-17: SCL 91 93 90 92 SDA Stop Condition Start Condition Note: Refer to Figure 26-5 for load conditions. TABLE 26-18: I2CTM BUS START/STOP BITS REQUIREMENTS (SLAVE MODE) Param. Symbol No. 90 91 92 93 TSU:STA THD:STA TSU:STO Characteristic Max Units Conditions ns Only relevant for Repeated Start condition ns After this period, the first clock pulse is generated Start Condition 100 kHz mode 4700 -- Setup Time 400 kHz mode 600 -- Start Condition 100 kHz mode 4000 -- Hold Time 400 kHz mode 600 -- Stop Condition 100 kHz mode 4700 -- Setup Time 400 kHz mode 600 -- 100 kHz mode 4000 -- 400 kHz mode 600 -- THD:STO Stop Condition Hold Time FIGURE 26-18: Min ns ns I2CTM BUS DATA TIMING 103 102 100 101 SCL 90 106 107 91 92 SDA In 110 109 109 SDA Out Note: Refer to Figure 26-5 for load conditions. (c) 2008 Microchip Technology Inc. DS39631E-page 353 PIC18F2420/2520/4420/4520 TABLE 26-19: I2CTM BUS DATA REQUIREMENTS (SLAVE MODE) Param. Symbol No. 100 THIGH 101 91 106 107 92 109 110 2: -- s s -- -- 100 kHz mode 4.7 -- s 400 kHz mode 1.3 -- s MSSP module 1.5 TCY -- -- 1000 ns 20 + 0.1 CB 300 ns 100 kHz mode -- 300 ns 400 kHz mode 20 + 0.1 CB 300 ns CB is specified to be from 10 to 400 pF TSU:STA Start Condition Setup Time 100 kHz mode 4.7 -- s 400 kHz mode 0.6 -- s Only relevant for Repeated Start condition THD:STA Start Condition Hold Time 100 kHz mode 4.0 -- s 400 kHz mode 0.6 -- s THD:DAT Data Input Hold Time 100 kHz mode 0 -- ns 400 kHz mode 0 0.9 s TSU:DAT Data Input Setup Time 100 kHz mode 250 -- ns 400 kHz mode 100 -- ns TSU:STO Stop Condition Setup Time 100 kHz mode 4.7 -- s 400 kHz mode 0.6 -- s TAA 100 kHz mode -- 3500 ns 400 kHz mode -- -- ns CB Note 1: 4.0 Conditions 0.6 TBUF D102 Units 1.5 TCY TF 90 100 kHz mode Max MSSP module TR 103 Clock High Time Min 400 kHz mode TLOW 102 Characteristic Clock Low Time SDA and SCL Rise 100 kHz mode Time 400 kHz mode SDA and SCL Fall Time Output Valid from Clock Bus Free Time 100 kHz mode 4.7 -- s 400 kHz mode 1.3 -- s -- 400 pF Bus Capacitive Loading CB is specified to be from 10 to 400 pF After this period, the first clock pulse is generated (Note 2) (Note 1) Time the bus must be free before a new transmission can start As a transmitter, the device must provide this internal minimum delay time to bridge the undefined region (min. 300 ns) of the falling edge of SCL to avoid unintended generation of Start or Stop conditions. A Fast mode I2C bus device can be used in a Standard mode I2C bus system, but the requirement TSU:DAT 250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line, TR max. + TSU:DAT = 1000 + 250 = 1250 ns (according to the Standard mode I2C bus specification), before the SCL line is released. DS39631E-page 354 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 MASTER SSP I2CTM BUS START/STOP BITS TIMING WAVEFORMS FIGURE 26-19: SCL 93 91 90 92 SDA Stop Condition Start Condition Note: Refer to Figure 26-5 for load conditions. TABLE 26-20: MASTER SSP I2CTM BUS START/STOP BITS REQUIREMENTS Param. Symbol No. 90 91 TSU:STA Characteristic ns Only relevant for Repeated Start condition ns After this period, the first clock pulse is generated 100 kHz mode 2(TOSC)(BRG + 1) -- 400 kHz mode 2(TOSC)(BRG + 1) -- 1 MHz mode(1) 2(TOSC)(BRG + 1) -- 100 kHz mode 2(TOSC)(BRG + 1) -- 400 kHz mode 2(TOSC)(BRG + 1) -- 1 MHz mode(1) 2(TOSC)(BRG + 1) -- 100 kHz mode 2(TOSC)(BRG + 1) -- 400 kHz mode 2(TOSC)(BRG + 1) -- 1 MHz mode(1) 2(TOSC)(BRG + 1) -- 100 kHz mode 2(TOSC)(BRG + 1) -- 400 kHz mode 2(TOSC)(BRG + 1) -- 1 MHz mode(1) 2(TOSC)(BRG + 1) -- THD:STA Start Condition TSU:STO Stop Condition THD:STO Stop Condition Hold Time Note 1: Maximum pin capacitance = 10 pF for all FIGURE 26-20: Units Setup Time Setup Time 93 Max Start Condition Hold Time 92 Min I2C Conditions ns ns pins. MASTER SSP I2CTM BUS DATA TIMING 103 102 100 101 SCL 90 106 91 107 92 SDA In 109 109 110 SDA Out Note: Refer to Figure 26-5 for load conditions. (c) 2008 Microchip Technology Inc. DS39631E-page 355 PIC18F2420/2520/4420/4520 TABLE 26-21: MASTER SSP I2CTM BUS DATA REQUIREMENTS Param. Symbol No. 100 101 THIGH TLOW Characteristic Min Max Units Clock High Time 100 kHz mode 2(TOSC)(BRG + 1) -- ms 400 kHz mode 2(TOSC)(BRG + 1) -- ms 1 MHz mode(1) 2(TOSC)(BRG + 1) -- ms Clock Low Time 100 kHz mode 2(TOSC)(BRG + 1) -- ms 400 kHz mode 2(TOSC)(BRG + 1) -- ms (1) 2(TOSC)(BRG + 1) -- ms 100 kHz mode -- 1000 ns 400 kHz mode 20 + 0.1 CB 300 ns 1 MHz mode(1) -- 300 ns 1 MHz mode 102 103 90 91 TR TF TSU:STA SDA and SCL Rise Time SDA and SCL Fall Time Start Condition Setup Time THD:STA Start Condition Hold Time 100 kHz mode -- 300 ns 400 kHz mode 20 + 0.1 CB 300 ns 1 MHz mode(1) -- 100 ns 100 kHz mode 2(TOSC)(BRG + 1) -- ms 400 kHz mode 2(TOSC)(BRG + 1) -- ms 1 MHz mode(1) 2(TOSC)(BRG + 1) -- ms 100 kHz mode 2(TOSC)(BRG + 1) -- ms 400 kHz mode 2(TOSC)(BRG + 1) -- ms 1 MHz mode(1) 2(TOSC)(BRG + 1) -- ms 0 -- ns 106 THD:DAT Data Input Hold Time 100 kHz mode 400 kHz mode 0 0.9 ms 107 TSU:DAT 100 kHz mode 250 -- ns 92 TSU:STO Stop Condition Setup Time 109 110 D102 Note 1: 2: TAA TBUF CB Data Input Setup Time Output Valid from Clock Bus Free Time 400 kHz mode 100 -- ns 100 kHz mode 2(TOSC)(BRG + 1) -- ms 400 kHz mode 2(TOSC)(BRG + 1) -- ms 1 MHz mode(1) 2(TOSC)(BRG + 1) -- ms 100 kHz mode -- 3500 ns 400 kHz mode -- 1000 ns (1) 1 MHz mode -- -- ns 100 kHz mode 4.7 -- ms 400 kHz mode 1.3 -- ms -- 400 pF Bus Capacitive Loading Conditions CB is specified to be from 10 to 400 pF CB is specified to be from 10 to 400 pF Only relevant for Repeated Start condition After this period, the first clock pulse is generated (Note 2) Time the bus must be free before a new transmission can start 2C Maximum pin capacitance = 10 pF for all I pins. A Fast mode I2C bus device can be used in a Standard mode I2C bus system, but parameter 107 250 ns must then be met. This will automatically be the case if the device does not stretch the LOW period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line, parameter 102 + parameter 107 = 1000 + 250 = 1250 ns (for 100 kHz mode), before the SCL line is released. DS39631E-page 356 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-21: EUSART SYNCHRONOUS TRANSMISSION (MASTER/SLAVE) TIMING RC6/TX/CK pin 121 121 RC7/RX/DT pin 120 Note: 122 Refer to Figure 26-5 for load conditions. TABLE 26-22: EUSART SYNCHRONOUS TRANSMISSION REQUIREMENTS Param No. 120 121 122 Symbol Characteristic TckH2dtV SYNC XMIT (MASTER & SLAVE) Clock High to Data Out Valid Tckrf Tdtrf Min Max Units PIC18FXXXX -- 40 ns PIC18LFXXXX -- 100 ns Clock Out Rise Time and Fall Time (Master mode) PIC18FXXXX -- 20 ns PIC18LFXXXX -- 50 ns Data Out Rise Time and Fall Time PIC18FXXXX -- 20 ns PIC18LFXXXX -- 50 ns (c) 2008 Microchip Technology Inc. Conditions VDD = 2.0V VDD = 2.0V VDD = 2.0V DS39631E-page 357 PIC18F2420/2520/4420/4520 FIGURE 26-22: EUSART SYNCHRONOUS RECEIVE (MASTER/SLAVE) TIMING RC6/TX/CK pin 125 RC7/RX/DT pin 126 Note: Refer to Figure 26-5 for load conditions. TABLE 26-23: EUSART SYNCHRONOUS RECEIVE REQUIREMENTS Param. No. Symbol Characteristic Min Max Units 125 TdtV2ckl SYNC RCV (MASTER & SLAVE) Data Hold before CK (DT hold time) 10 -- ns 126 TckL2dtl Data Hold after CK (DT hold time) 15 -- ns Conditions TABLE 26-24: A/D CONVERTER CHARACTERISTICS: PIC18F2420/2520/4420/4520 (INDUSTRIAL) PIC18LF2420/2520/4420/4520 (INDUSTRIAL) Param Symbol No. Characteristic Min Typ Max Units Conditions VREF 3.0V A01 NR Resolution -- -- 10 A03 EIL Integral Linearity Error -- -- <1 LSb VREF 3.0V A04 EDL Differential Linearity Error -- -- <1 LSb VREF 3.0V A06 EOFF Offset Error -- -- <2.0 LSb VREF 3.0V A07 EGN Gain Error -- -- <1 LSb VREF 3.0V A10 -- Monotonicity A20 VREF Reference Voltage Range (VREFH - VREFL) 1.8 3 -- -- A21 VREFH Reference Voltage High VSS A22 VREFL Reference Voltage Low A25 VAIN Analog Input Voltage A30 ZAIN Recommended Impedance of Analog Voltage Source A40 IAD A/D Current from PIC18FXXXX VDD PIC18LFXX20 A50 IREF Note 1: 2: VREF Input Current(2) Guaranteed(1) bit -- VSS VAIN VREF -- -- V V VDD < 3.0V VDD 3.0V -- VREFH V VSS - 0.3V -- VDD - 3.0V V VREFL -- VREFH V -- -- 2.5 k -- 180 -- A -- 90 -- A -- -- -- -- 5 150 A A Average current during conversion During VAIN acquisition. During A/D conversion cycle. The A/D conversion result never decreases with an increase in the input voltage and has no missing codes. VREFH current is from RA3/AN3/VREF+ pin or VDD, whichever is selected as the VREFH source. VREFL current is from RA2/AN2/VREF-/CVREF pin or VSS, whichever is selected as the VREFL source. DS39631E-page 358 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 26-23: A/D CONVERSION TIMING BSF ADCON0, GO (Note 2) 131 Q4 130 132 (1) A/D CLK 9 A/D DATA 8 7 ... ... 2 1 0 NEW_DATA OLD_DATA ADRES TCY ADIF GO DONE SAMPLING STOPPED SAMPLE Note 1: If the A/D clock source is selected as RC, a time of TCY is added before the A/D clock starts. This allows the SLEEP instruction to be executed. 2: This is a minimal RC delay (typically 100 ns), which also disconnects the holding capacitor from the analog input. TABLE 26-25: A/D CONVERSION REQUIREMENTS Param Symbol No. 130 TAD Characteristic A/D Clock Period Min Max Units 0.7 25.0(1) s TOSC based, VREF 3.0V PIC18LFXXXX 1.4 25.0(1) s VDD = 2.0V; TOSC based, VREF full range PIC18FXXXX -- 1 s A/D RC mode VDD = 2.0V; A/D RC mode PIC18FXXXX PIC18LFXXXX -- 3 s 131 TCNV Conversion Time (not including acquisition time) (Note 2) 11 12 TAD 132 TACQ Acquisition Time (Note 3) 1.4 -- s 135 TSWC Switching Time from Convert Sample -- (Note 4) TBD TDIS Discharge Time 0.2 -- Note 1: 2: 3: 4: Conditions -40C to +85C s The time of the A/D clock period is dependent on the device frequency and the TAD clock divider. ADRES register may be read on the following TCY cycle. The time for the holding capacitor to acquire the "New" input voltage when the voltage changes full scale after the conversion (VDD to VSS or VSS to VDD). The source impedance (RS) on the input channels is 50. On the following cycle of the device clock. (c) 2008 Microchip Technology Inc. DS39631E-page 359 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 360 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 27.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES 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. Note: "Typical" represents the mean of the distribution at 25C. "Maximum" or "minimum" represents (mean + 3) or (mean - 3) respectively, where is a standard deviation, over the whole temperature range. FIGURE 27-1: SLEEP MODE 100 Test instrument results are compressed to about 0.05 A for actual values below 0.05 mA. Measurements below 0.01 mA are suspect and considered unmeasurable . This is supported by the instrument specifications. 10 5.5 5.0 Ipd (uA) 4.5 4.0 3.5 1 3.0 2.5 2.0 0.1 0.01 -50 -25 0 25 50 75 100 125 Temp (C) (c) 2008 Microchip Technology Inc. DS39631E-page 361 PIC18F2420/2520/4420/4520 FIGURE 27-2: TYPICAL IPD vs. VDD ACROSS TEMPERATURE (SLEEP MODE) 100 10 IPD (uA) 125C 85C 1 25C 0.1 -40C 0.01 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 5.0 5.5 VDD (V) FIGURE 27-3: MAXIMUM IPD vs. VDD ACROSS TEMPERATURE (SLEEP MODE) 100 125C 10 IPD (uA) 85C 1 25C -40C 0.1 0.01 2.0 2.5 3.0 3.5 4.0 4.5 VDD (V) DS39631E-page 362 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-4: TYPICAL T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP, T1OSC IN LOW-POWER MODE) 3.0 2.5 IPD (uA) 2.0 85C 1.5 25C 1.0 -10C 0.5 0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-5: MAXIMUM T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP, TIOSC IN LOW-POWER MODE) 4 3 IPD (uA) 85C 25C -10C 2 1 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 363 PIC18F2420/2520/4420/4520 FIGURE 27-6: TYPICAL T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP, T1OSC IN HIGH-POWER MODE) 16 14 12 IPD (uA) 10 8 85C 25C 6 -40C 4 2 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 DD FIGURE 27-7: MAXIMUM T1OSC DELTA CURRENT vs. VDD ACROSS TEMP. (DEVICE IN SLEEP, T1OSC IN HIGH-POWER MODE) 30 25 IPD (uA) 20 15 85C 10 25C -40C 5 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 V DD (V) DS39631E-page 364 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-8: TYPICAL BOR DELTA CURRENT vs. VDD ACROSS TEMP. (BORV = 2.7V, SLEEP MODE) 55.00 50.00 Device Held in RESET 45.00 MAX IPD (uA) MAX (85C) 40.00 TYP (25C) 35.00 MIN (-40C) 30.00 Device in SLEEP 25.00 20.00 2 2.5 3 3.5 4 4.5 5 5.5 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 365 PIC18F2420/2520/4420/4520 FIGURE 27-9: TYPICAL WDT CURRENT vs. VDD ACROSS TEMPERATURE (WDT DELTA CURRENT IN SLEEP MODE) 6.00 125C 5.00 25C -40C 4.00 IPD (uA) 85C 3.00 2.00 1.00 0.00 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-10: MAXIMUM WDT CURRENT vs. VDD ACROSS TEMPERATURE (WDT DELTA CURRENT IN SLEEP MODE) 12.0 10.0 125C 8.0 IPD (uA) 85C 6.0 25C -40C 4.0 2.0 0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) DS39631E-page 366 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-11: TYPICAL IDD ACROSS VDD (RC_RUN MODE, +25C) 10 4.2V 8 MHz IDD (mA) 4 MHz 2 MHz 1 MHz 1 500 kHz 250 kHz 125 kHz 0.1 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-12: MAXIMUM IDD ACROSS VDD (RC_RUN MODE, +85C) 10 8 MHz 4.2V IDD (mA) 4 MHz 2 MHz 1 MHz 1 500 kHz 250 kHz 125 kHz 0.1 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 367 PIC18F2420/2520/4420/4520 FIGURE 27-13: TYPICAL AND MAXIMUM IDD ACROSS VDD (RC_RUN MODE, 31 kHz) IDD (uA) 1000 Maximum (-40C) 100 Typical (25C) 10 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-14: TYPICAL IDD ACROSS VDD (RC_IDLE MODE, +25C) 10 4.2V 1 8 MHz 4 MHz IDD (mA) 2 MHz 1 MHz 250 kHz 125 kHz 0.1 500 kHz 0.01 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) DS39631E-page 368 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-15: MAXIMUM IDD ACROSS VDD (RC_IDLE MODE, -40C TO +85C) 10 4.2V IDD (mA) 8 MHz 4 MHz 1 2 MHz 1 MHz 500 kHz 250 kHz 125 kHz 0.1 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-16: TYPICAL AND MAXIMUM IDD ACROSS VDD (RC_IDLE MODE, 31 kHz) 25 20 IDD (uA) 15 Maximum (85C) 10 Typical (25C) 5 0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 369 PIC18F2420/2520/4420/4520 FIGURE 27-17: TYPICAL AND MAXIMUM SEC_RUN CURRENT vs. VDD ACROSS TEMPERATURE (T1OSC IN LOW-POWER MODE) 140.0 120.0 Max (-10C) IDD (uA) 100.0 80.0 60.0 Typ (25C) Typ (85C) Typ (-10C) 40.0 20.0 0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) FIGURE 27-18: TYPICAL AND MAXIMUM SEC_IDLE CURRENT vs. VDD ACROSS TEMPERATURE (T1OSC IN LOW-POWER MODE) 14.0 12.0 Typ (25C) 10.0 IDD (uA) Max (85C) 8.0 Typ (85C) 6.0 Typ (-10C) 4.0 2.0 0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) DS39631E-page 370 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-19: TYPICAL IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_RUN MODE (EC CLOCK), +25C) 3.0 2.5 5.5V 5.0V IDD (mA) 2.0 4.5V 4.0V 1.5 3.5V 3.0V 1.0 2.5V 2.0V 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Fosc (MHz) FIGURE 27-20: MAXIMUM IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_RUN MODE (EC CLOCK), -40C TO +125C) 4.5 5.5V IDD (mA) 4.0 3.5 5.0V 3.0 4.5V 2.5 4.0V 2.0 3.5V 1.5 3.0V 1.0 2.5V 2.0V 0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Fosc (MHz) (c) 2008 Microchip Technology Inc. DS39631E-page 371 PIC18F2420/2520/4420/4520 FIGURE 27-21: TYPICAL IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_RUN MODE (EC CLOCK), +25C) 20 5.5V 18 5.0V 16 4.5V 14 4.0V IDD (mA) 12 10 3.5V 8 6 3.0V 4 2.5V 2 2.0V 0 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Fosc (MHz) FIGURE 27-22: MAXIMUM IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_RUN MODE (EC CLOCK), -40C TO +125C) 24 22 5.5V 20 5.0V 18 4.5V IDD (mA) 16 4.0V 14 12 10 3.5V 8 6 3.0V 4 2.5V 2 2.0V 0 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Fosc (MHz) DS39631E-page 372 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-23: TYPICAL IDD vs. FOSC, HS/PLL (PRI_RUN MODE, +25C) 24 22 20 18 5.5V IDD (mA) 16 5.0V 14 4.5V 12 4.2V 10 8 6 4 16 18 20 22 24 26 28 30 32 34 36 38 40 34 36 38 40 Fosc (MHz) FIGURE 27-24: MAXIMUM IDD vs. FOSC, HS/PLL (PRI_RUN MODE, -40C) 24 22 20 5.5V 18 5.0V I DD (mA) 16 4.5V 14 4.2V 12 10 8 6 4 16 18 20 22 24 26 28 30 32 Fosc (MHz) (c) 2008 Microchip Technology Inc. DS39631E-page 373 PIC18F2420/2520/4420/4520 FIGURE 27-25: TYPICAL IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_IDLE MODE, +25C) 1.1 1.0 0.9 5.5V 0.8 5.0V IDD (mA) 0.7 4.5V 0.6 4.0V 0.5 3.5V 0.4 3.0V 2.5V 0.3 2.0V 0.2 0.1 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Fosc (MHz) FIGURE 27-26: MAXIMUM IDD vs. FOSC, 500 kHz TO 4 MHz (PRI_IDLE MODE, -40C TO +125C) 1.2 1.1 1.0 5.5V 0.9 5.0V IDD (mA) 0.8 4.5V 0.7 4.0V 0.6 3.5V 0.5 3.0V 0.4 2.5V 0.3 2.0V 0.2 0.1 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Fosc (MHz) DS39631E-page 374 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-27: TYPICAL IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_IDLE MODE, +25C) 12 11 IDD (mA) 10 9 5.5V 8 5.0V 7 4.5V 4.0V 6 5 3.5V 4 3 3.0V 2 2.5V 1 2.0V 0 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Fosc (MHz) FIGURE 27-28: MAXIMUM IDD vs. FOSC, 4 MHz TO 40 MHz (PRI_IDLE MODE, -40C TO +125C) 12 11 10 5.5V 9 5.0V 8 IDD (mA) 4.5V 7 4.0V 6 5 3.5V 4 3 3.0V 2 2.5V 1 2.0V 0 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40 Fosc (MHz) (c) 2008 Microchip Technology Inc. DS39631E-page 375 PIC18F2420/2520/4420/4520 FIGURE 27-29: TYPICAL IDD vs. FOSC, HS/PLL (PRI_IDLE MODE, +25C) 12 11 10 9 IDD (mA) 8 5.5V 7 5.0V 6 4.5V 4.2V 5 4 3 2 1 0 16 18 20 22 24 26 28 30 32 34 36 38 40 34 36 38 40 Fosc (MHz) FIGURE 27-30: MAXIMUM IDD vs. FOSC, HS/PLL (PRI_IDLE MODE, -40C) 12 11 10 9 5.5V 8 IDD (mA) 5.0V 7 4.5V 4.2V 6 5 4 3 2 1 0 16 18 20 22 24 26 28 30 32 Fosc (MHz) DS39631E-page 376 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-31: VIN (ST) vs. VDD, +25C (-40C TO +125C) 4.0 3.5 3.0 VIH Min (-40C) VIH Typ (25C) VIH Max (125C) VIN (V) 2.5 2.0 1.5 1.0 VIL Min (125C) 0.5 VIL Max (-40C) VIL Typ (25C) 0.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 4.5 5.0 5.5 VDD (V) FIGURE 27-32: VIN (TTL) vs. VDD, +25C (-40C TO +125C) 1.6 VIH Max (-40C) 1.4 VIH Typ (25C) VIH Min (125C) 1.2 VIN (V) 1.0 0.8 0.6 0.4 0.2 0.0 2.0 2.5 3.0 3.5 4.0 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 377 PIC18F2420/2520/4420/4520 FIGURE 27-33: VOL vs. IOL (VDD = 3.0V, -40C TO +85C) 2.0 1.8 1.6 1.4 Max (85C) VOL (V) 1.2 1.0 0.8 Typ (25C) 0.6 0.4 Min (-40C) 0.2 0.0 0 5 10 15 20 25 20 25 IOL (-ma) FIGURE 27-34: VOL vs. IOL (VDD = 5.0V, -40C TO +125C) 2.0 1.8 1.6 1.4 VOL (V) 1.2 1.0 0.8 Max (85C) 0.6 Typ (25C) 0.4 0.2 Min (-40C) 0.0 0 5 10 15 I OL (-ma) DS39631E-page 378 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-35: VOH vs. IOH (VDD = 3.0V, -40C TO +85C) 3.0 2.5 2.0 VOH (V) Max (-40C) 1.5 Typ (25C) Min (85C) 1.0 0.5 0.0 0 5 10 15 20 25 I OH (-ma) FIGURE 27-36: VOH vs. IOH (VDD = 5.0V, -40C TO +125C) 5.0 4.5 Max (-40C) 4.0 3.5 Typ (25C) VOH (V) 3.0 2.5 Min (125C) 2.0 1.5 1.0 0.5 0.0 0 5 10 15 20 25 I OH (-ma) (c) 2008 Microchip Technology Inc. DS39631E-page 379 PIC18F2420/2520/4420/4520 FIGURE 27-37: INTOSC FREQUENCY vs. VDD, TEMPERATURE (-40C, +25C, +85C, +125C) 8.4 Max Freq 8.3 8.2 125C Typ 85C Typ Freq (MHz) 8.1 25C Typ 8.0 -40C Typ 7.9 7.8 Min Freq 7.7 7.6 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 5.0 5.5 VDD (V) FIGURE 27-38: INTRC vs. VDD ACROSS TEMPERATURE (-40C TO +125C) 40 39 38 37 Max (125C) 36 Freq (kHz) 35 34 Max (-40C) 33 32 31 Typ (25C) 30 Min (85C) 29 28 27 Min (125C) 26 25 2.0 2.5 3.0 3.5 4.0 4.5 VDD (V) DS39631E-page 380 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 FIGURE 27-39: WDT PERIOD vs. VDD ACROSS TEMPERATURE (1:1 POSTSCALER, -40C TO +125C) 4.6 Longest 4.4 4.2 Shortest (85C) Typical (25C) Shortest (125C) Period (ms) 4.0 3.8 3.6 3.4 3.2 3.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VDD (V) (c) 2008 Microchip Technology Inc. DS39631E-page 381 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 382 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 28.0 PACKAGING INFORMATION 28.1 Package Marking Information 28-Lead SPDIP Example PIC18F2520-I/SP e3 0810017 XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX YYWWNNN 28-Lead SOIC Example XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXX YYWWNNN 28-Lead QFN Example XXXXXXXX XXXXXXXX YYWWNNN 18F2420 -I/ML e3 0810017 Legend: XX...X Y YY WW NNN e3 * Note: PIC18F2520-E/SO e3 0810017 Customer-specific information Year code (last digit of calendar year) Year code (last 2 digits of calendar year) Week code (week of January 1 is week `01') Alphanumeric traceability code Pb-free JEDEC designator for Matte Tin (Sn) This package is Pb-free. The Pb-free JEDEC designator ( e3 ) can be found on the outer packaging for this package. In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line, thus limiting the number of available characters for customer-specific information. (c) 2008 Microchip Technology Inc. DS39631E-page 383 PIC18F2420/2520/4420/4520 Package Marking Information (Continued) 40-Lead PDIP Example PIC18F4420-I/P e3 0810017 XXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXX YYWWNNN 44-Lead QFN XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX YYWWNNN 44-Lead TQFP XXXXXXXXXX XXXXXXXXXX XXXXXXXXXX YYWWNNN DS39631E-page 384 Example PIC18F4520 -I/ML e3 0810017 Example PIC18F4420 -I/PT e3 0810017 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 28.2 Package Details The following sections give the technical details of the packages. !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 N NOTE 1 E1 1 2 3 D E A2 A L c b1 A1 b e eB 6&! '! 9'&! 7"') %! 7,8. 7 7 & ; < & & 7: 1, = = - 1!& & = = . - -- ##4 "# & 4!! "# >#& ##4>#& . < : 9& - -? 9 - < ) ) < 1 = = & & 9# 6 4!! 9#>#& 9 * 9#>#& : * + - !" !"#$%&" ' ()"&'"!&) &#*& & & # +%&, & !& - '! !#.# &"#' #%! & "! ! #%! & "! !! &$#/ !# '! #& .0 1,2 1!'! &$& "! **& "&& ! (c) 2008 Microchip Technology Inc. * ,1 DS39631E-page 385 PIC18F2420/2520/4420/4520 # # $ % &'( #) !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 D N E E1 NOTE 1 1 2 3 e b h A2 A h c L A1 L1 6&! '! 9'&! 7"') %! 99. . 7 7: 7 ; < & : 8 & = = = = = - ##4 4!! &# %%+ 1, : >#& . ##4>#& . 1, : 9& 1, , '% @ & A 3 &9& 9 3 & & 9 3 & ? -1, = = .3 I B = <B < = -- 9#>#& ) - = # %& D B = B # %&1 && ' E B = 9# 4!! B !" !"#$%&" ' ()"&'"!&) &#*& & & # +%&, & !& - '! !#.# &"#' #%! & "! ! #%! & "! !! &$#'' !# '! #& .0 1,2 1!'! &$& "! **& "&& ! .32 % '! ("!"*& "&& (% % '& " !! DS39631E-page 386 * ,1 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 * +% ! , - ./. *+! 0 1 '(( ) ,1 !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 D D2 EXPOSED PAD e E b E2 2 2 1 1 N K N NOTE 1 L BOTTOM VIEW TOP VIEW A A3 A1 6&! '! 9'&! 7"') %! 99. . 7 7 7: ; < & : 8 & < &# %% , && 4!! - : >#& . .$ . !##>#& : 9& .$ !##9& ?1, .3 ?1, -? - ?1, -? - , &&>#& ) - - - , &&9& 9 , &&& .$ !## C = !" !"#$%&" ' ()"&'"!&) &#*& & & # 4!!*!"&# - '! #& .0 1,2 1!'! &$& "! **& "&& ! .32 % '! ("!"*& "&& (% % '& " !! (c) 2008 Microchip Technology Inc. = * ,1 DS39631E-page 387 PIC18F2420/2520/4420/4520 * +% ! , - ./. *+! 0 1 '(( ) ,1 !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 DS39631E-page 388 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 2 . !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 N NOTE 1 E1 1 2 3 D E A2 A L c b1 A1 b e eB 6&! '! 9'&! 7"') %! 7,8. 7 7 & ; & & 7: 1, = = = 1!& & = = . = ? ##4 "# & 4!! "# >#& ##4>#& . < = < : 9& < = 9 = < = ) - = ) = - 1 = = & & 9# 6 4!! 9#>#& 9 * 9#>#& : * + !" !"#$%&" ' ()"&'"!&) &#*& & & # +%&, & !& - '! !#.# &"#' #%! & "! ! #%! & "! !! &$#/ !# '! #& .0 1,2 1!'! &$& "! **& "&& ! (c) 2008 Microchip Technology Inc. * ,?1 DS39631E-page 389 PIC18F2420/2520/4420/4520 22 * +% ! , - / *+! !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 D D2 EXPOSED PAD e E E2 b 2 2 1 N 1 N NOTE 1 TOP VIEW K L BOTTOM VIEW A A3 A1 6&! '! 9'&! 7"') %! 99. . 7 7 7: ; & : 8 & < &# %% , && 4!! - : >#& . .$ . !##>#& : 9& .$ !##9& ?1, .3 <1, ?- ? ?< <1, ?- ? , &&>#& ) - -< , &&9& 9 - , &&& .$ !## C = !" !"#$%&" ' ()"&'"!&) &#*& & & # 4!!*!"&# - '! #& .0 1,2 1!'! &$& "! **& "&& ! .32 % '! ("!"*& "&& (% % '& " !! DS39631E-page 390 ?< = * ,-1 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 22 * +% ! , - / *+! !" 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 (c) 2008 Microchip Technology Inc. DS39631E-page 391 PIC18F2420/2520/4420/4520 22 31 !" * +4 3 5/5/5 % ' 3*+ 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 D D1 E e E1 N b NOTE 1 1 2 3 NOTE 2 A c L A1 6&! '! 9'&! 7"') %9#! A2 L1 99. . 7 7 7: ; 9#& : 8 & = = = ? ##4 4!! &# %% 3 &9& 9 3 & & 9 3 & : >#& I <1, .3 B -B B . 1, : 9& 1, ##4>#& . 1, ##49& 1, 9# = 9#>#& 4!! ) - - # %& D B B -B # %&1 && ' E B B -B !" !"#$%&" ' ()"&'"!&) &#*& & & # , '% !& ! & D!E' - '! !#.# &"#' #%! & "! ! #%! & "! !! &$#'' !# '! #& .0 1,2 1!'! &$& "! **& "&& ! .32 % '! ("!"*& "&& (% % '& " !! DS39631E-page 392 * ,?1 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 22 31 !" * +4 3 5/5/5 % ' 3*+ 3 & ' !&" & 4# *!( !!& 4 %& &#& && 255***' '5 4 (c) 2008 Microchip Technology Inc. DS39631E-page 393 PIC18F2420/2520/4420/4520 NOTES: DS39631E-page 394 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 APPENDIX A: REVISION HISTORY Revision A (June 2004) Original data sheet for PIC18F2420/2520/4420/4520 devices. APPENDIX B: DEVICE DIFFERENCES The differences between the devices listed in this data sheet are shown in Table B-1. Revision B (January 2007) This revision includes updates to the packaging diagrams. Revision C (June 2007) This revision includes updates to Section 6.0 "Flash Program Memory", Section 23.0 "Special Features of the CPU", Section 26.0 "Electrical Characteristics" and minor corrections applicable to Timer1, EUSART and the packaging diagrams. Also added the 125C specifications. Revision D (July 2007) This revision updated the extended temperature information in Section 26.0 "Electrical Characteristics". Revision E (October 2008) This revision updated Section 26.0 "Electrical Characteristics", Section 27.0 "DC and AC Characteristics Graphs and Tables" and Section 28.0 "Packaging Information". TABLE B-1: DEVICE DIFFERENCES Features PIC18F2420 PIC18F2520 PIC18F4420 PIC18F4520 Program Memory (Bytes) 16384 32768 16384 32768 Program Memory (Instructions) 8192 16384 8192 16384 Interrupt Sources 19 19 20 20 Ports A, B, C, (E) Ports A, B, C, (E) Ports A, B, C, D, E Ports A, B, C, D, E Capture/Compare/PWM Modules 2 2 1 1 Enhanced Capture/Compare/PWM Modules 0 0 1 1 I/O Ports Parallel Communications (PSP) No No Yes Yes 10-Bit Analog-to-Digital Module 10 Input Channels 10 Input Channels 13 Input Channels 13 Input Channels 28-Pin SPDIP 28-Pin SOIC 28-Pin QFN 28-Pin SPDIP 28-Pin SOIC 28-Pin QFN 40-Pin PDIP 44-Pin TQFP 44-Pin QFN 40-Pin PDIP 44-Pin TQFP 44-Pin QFN Packages (c) 2008 Microchip Technology Inc. DS39631E-page 395 PIC18F2420/2520/4420/4520 APPENDIX C: MIGRATION FROM MID-RANGE TO ENHANCED DEVICES A detailed discussion of the differences between the mid-range MCU devices (i.e., PIC16CXXX) and the enhanced devices (i.e., PIC18FXXX) is provided in AN716, "Migrating Designs from PIC16C74A/74B to PIC18C442". The changes discussed, while device specific, are generally applicable to all mid-range to enhanced device migrations. APPENDIX D: MIGRATION FROM HIGH-END TO ENHANCED DEVICES A detailed discussion of the migration pathway and differences between the high-end MCU devices (i.e., PIC17CXXX) and the enhanced devices (i.e., PIC18FXXX) is provided in AN726, "PIC17CXXX to PIC18CXXX Migration". This Application Note is available as Literature Number DS00726. This Application Note is available as Literature Number DS00716. DS39631E-page 396 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 INDEX A A/D ....................................................................................223 Acquisition Requirements .........................................228 ADCON0 Register.....................................................223 ADCON1 Register.....................................................223 ADCON2 Register.....................................................223 ADRESH Register............................................. 223, 226 ADRESL Register .....................................................223 Analog Port Pins, Configuring ...................................230 Associated Registers ................................................232 Configuring the Module .............................................227 Conversion Clock (TAD) ............................................229 Conversion Status (GO/DONE Bit) ...........................226 Conversions ..............................................................231 Converter Characteristics..........................................359 Converter Interrupt, Configuring................................227 Discharge ..................................................................231 Operation in Power-Managed Modes .......................230 Selecting and Configuring Acquisition Time..............229 Special Event Trigger (CCP) .....................................232 Special Event Trigger (ECCP) ..................................148 Use of the CCP2 Trigger ...........................................232 Absolute Maximum Ratings...............................................321 AC (Timing) Characteristics ..............................................340 Load Conditions for Device Timing Specifications ........................................341 Parameter Symbology...............................................340 Temperature and Voltage Specifications ..................341 Timing Conditions .....................................................341 AC Characteristics Internal RC Accuracy ................................................343 Access Bank Mapping with Indexed Literal Offset Mode ..................72 ACKSTAT..........................................................................191 ACKSTAT Status Flag.......................................................191 ADCON0 Register .............................................................223 GO/DONE Bit ............................................................226 ADCON1 Register .............................................................223 ADCON2 Register .............................................................223 ADDFSR............................................................................310 ADDLW .............................................................................273 ADDULNK .........................................................................310 ADDWF .............................................................................273 ADDWFC...........................................................................274 ADRESH Register .............................................................223 ADRESL Register...................................................... 223, 226 Analog-to-Digital Converter. See A/D. ANDLW .............................................................................274 ANDWF .............................................................................275 Assembler MPASM Assembler ...................................................318 Auto-Wake-up on Sync Break Character ..........................214 B Bank Select Register (BSR) ................................................59 Baud Rate Generator ........................................................187 BC .....................................................................................275 BCF ...................................................................................276 BF......................................................................................191 BF Status Flag...................................................................191 DS39631E-page 397 Block Diagrams A/D............................................................................ 226 Analog Input Model ................................................... 227 Baud Rate Generator................................................ 187 Capture Mode Operation .......................................... 141 Comparator Analog Input Model ............................... 237 Comparator I/O Operating Modes ............................ 234 Comparator Output ................................................... 236 Comparator Voltage Reference ................................ 240 Comparator Voltage Reference Output Buffer Example ................................................. 241 Compare Mode Operation ........................................ 142 Device Clock............................................................... 28 Enhanced PWM........................................................ 149 EUSART Receive ..................................................... 213 EUSART Transmit .................................................... 211 External Power-on Reset Circuit (Slow VDD Power-up).......................................... 43 Fail-Safe Clock Monitor (FSCM) ............................... 261 Generic I/O Port........................................................ 105 High/Low-Voltage Detect with External Input ........... 244 Interrupt Logic ............................................................. 92 MSSP (I2C Master Mode) ......................................... 185 MSSP (I2C Mode) ..................................................... 170 MSSP (SPI Mode) .................................................... 161 On-Chip Reset Circuit ................................................. 41 PIC18F2420/2520....................................................... 10 PIC18F4420/4520....................................................... 11 PLL (HS Mode) ........................................................... 25 PORTD and PORTE (Parallel Slave Port) ................ 120 PWM Operation (Simplified) ..................................... 144 Reads from Flash Program Memory........................... 77 Single Comparator .................................................... 235 Table Read Operation ................................................ 73 Table Write Operation................................................. 74 Table Writes to Flash Program Memory ..................... 79 Timer0 in 16-Bit Mode .............................................. 124 Timer0 in 8-Bit Mode ................................................ 124 Timer1....................................................................... 128 Timer1 (16-Bit Read/Write Mode) ............................. 128 Timer2....................................................................... 134 Timer3....................................................................... 136 Timer3 (16-Bit Read/Write Mode) ............................. 136 Watchdog Timer ....................................................... 258 BN ..................................................................................... 276 BNC .................................................................................. 277 BNN .................................................................................. 277 BNOV................................................................................ 278 BNZ................................................................................... 278 BOR. See Brown-out Reset. BOV .................................................................................. 281 BRA................................................................................... 279 Break Character (12-Bit) Transmit and Receive ............... 216 BRG. See Baud Rate Generator. Brown-out Reset (BOR) ...................................................... 44 Detecting..................................................................... 44 Disabling in Sleep Mode ............................................. 44 Software Enabled ....................................................... 44 BSF ................................................................................... 279 BTFSC .............................................................................. 280 BTFSS .............................................................................. 280 BTG................................................................................... 281 BZ ..................................................................................... 282 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 C C Compilers MPLAB C18 .............................................................. 318 MPLAB C30 .............................................................. 318 CALL ................................................................................. 282 CALLW.............................................................................. 311 Capture (CCP Module)...................................................... 141 Associated Registers ................................................ 143 CCP Pin Configuration .............................................. 141 CCPRxH:CCPRxL Registers .................................... 141 Prescaler ................................................................... 141 Software Interrupt ..................................................... 141 Timer1/Timer3 Mode Selection ................................. 141 Capture (ECCP Module) ................................................... 148 Capture/Compare/PWM (CCP)......................................... 139 Capture Mode. See Capture. CCP Mode and Timer Resources ............................. 140 CCPRxH Register ..................................................... 140 CCPRxL Register...................................................... 140 Compare Mode. See Compare. Interaction of Two CCP Modules .............................. 140 Module Configuration ................................................ 140 Clock Sources ..................................................................... 28 Selecting the 31 kHz Source....................................... 29 Selection Using OSCCON Register ............................ 29 CLRF................................................................................. 283 CLRWDT........................................................................... 283 Code Examples 16 x 16 Signed Multiply Routine ................................. 90 16 x 16 Unsigned Multiply Routine ............................. 90 8 x 8 Signed Multiply Routine ..................................... 89 8 x 8 Unsigned Multiply Routine ................................. 89 Changing Between Capture Prescalers .................... 141 Computed GOTO Using an Offset Value .................... 56 Data EEPROM Read .................................................. 85 Data EEPROM Refresh Routine ................................. 86 Data EEPROM Write .................................................. 85 Erasing a Flash Program Memory Row ...................... 78 Fast Register Stack..................................................... 56 How to Clear RAM (Bank 1) Using Indirect Addressing ............................................. 68 Implementing a Real-Time Clock Using a Timer1 Interrupt Service ................................ 131 Initializing PORTA..................................................... 105 Initializing PORTB..................................................... 108 Initializing PORTC..................................................... 111 Initializing PORTD..................................................... 114 Initializing PORTE..................................................... 117 Loading the SSPBUF (SSPSR) Register .................. 164 Reading a Flash Program Memory Word ................... 77 Saving STATUS, WREG and BSR Registers in RAM .............................................. 103 Writing to Flash Program Memory ........................ 80-81 Code Protection ................................................................ 249 COMF................................................................................ 284 Comparator ....................................................................... 233 Analog Input Connection Considerations.................. 237 Associated Registers ................................................ 237 Configuration............................................................. 234 Effects of a Reset...................................................... 236 Interrupts................................................................... 236 Operation .................................................................. 235 Operation During Sleep ............................................ 236 Outputs ..................................................................... 235 Reference ................................................................. 235 DS39631E-page 398 External Signal ................................................. 235 Internal Signal................................................... 235 Response Time......................................................... 235 Comparator Specifications................................................ 338 Comparator Voltage Reference ........................................ 239 Accuracy and Error ................................................... 240 Associated Registers ................................................ 241 Configuring ............................................................... 239 Connection Considerations....................................... 240 Effects of a Reset ..................................................... 240 Operation During Sleep ............................................ 240 Compare (CCP Module) ................................................... 142 Associated Registers ................................................ 143 CCPRx Register ....................................................... 142 Pin Configuration ...................................................... 142 Software Interrupt ..................................................... 142 Special Event Trigger ............................... 137, 142, 232 Timer1/Timer3 Mode Selection................................. 142 Compare (ECCP Module)................................................. 148 Special Event Trigger ............................................... 148 Computed GOTO................................................................ 56 Configuration Bits ............................................................. 249 Configuration Register Protection..................................... 266 Context Saving During Interrupts...................................... 103 CPFSEQ ........................................................................... 284 CPFSGT ........................................................................... 285 CPFSLT ............................................................................ 285 Crystal Oscillator/Ceramic Resonator................................. 23 Customer Change Notification Service............................. 407 Customer Notification Service .......................................... 407 Customer Support............................................................. 407 D Data Addressing Modes ..................................................... 68 Comparing Addressing Modes with the Extended Instruction Set Enabled ...................... 71 Direct .......................................................................... 68 Indexed Literal Offset ................................................. 70 Instructions Affected ........................................... 70 Indirect ........................................................................ 68 Inherent and Literal..................................................... 68 Data EEPROM Code Protection ........................................................ 266 Data EEPROM Memory...................................................... 83 Associated Registers .................................................. 87 EEADR Register ......................................................... 83 EECON1 and EECON2 Registers .............................. 83 Operation During Code-Protect .................................. 86 Protection Against Spurious Write .............................. 86 Reading ...................................................................... 85 Using .......................................................................... 86 Write Verify ................................................................. 85 Writing ........................................................................ 85 Data Memory ...................................................................... 59 Access Bank............................................................... 62 and the Extended Instruction Set ............................... 70 Bank Select Register (BSR) ....................................... 59 General Purpose Registers ........................................ 62 Map for PIC18F2420/4420 ......................................... 60 Map for PIC18F2520/4520 ......................................... 61 Special Function Registers ......................................... 63 DAW ................................................................................. 286 DC and AC Characteristics Graphs and Tables ................................................... 361 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 DC Characteristics ............................................................335 Power-Down and Supply Current..............................325 Supply Voltage ..........................................................324 DCFSNZ............................................................................287 DECF.................................................................................286 DECFSZ ............................................................................287 Development Support........................................................317 Device Differences ............................................................395 Device Overview ...................................................................7 Details on Individual Family Members ..........................8 Features (table).............................................................9 New Core Features .......................................................7 Other Special Features .................................................8 Device Reset Timers ...........................................................45 Oscillator Start-up Timer (OST) ..................................45 PLL Lock Time-out ......................................................45 Power-up Timer (PWRT).............................................45 Time-out Sequence .....................................................45 Direct Addressing ................................................................69 E Effect on Standard PIC MCU Instructions .........................314 Effects of Power-Managed Modes on Various Clock Sources................................................31 Electrical Characteristics ...................................................321 Enhanced Capture/Compare/PWM (ECCP) .....................147 Associated Registers ................................................160 Capture and Compare Modes...................................148 Capture Mode. See Capture (ECCP Module). Outputs and Configuration ........................................148 Pin Configurations for ECCP.....................................148 PWM Mode. See PWM (ECCP Module). Standard PWM Mode................................................148 Timer Resources.......................................................148 Enhanced PWM Mode. See PWM (ECCP Module). Enhanced Universal Synchronous Asynchronous Receiver Transmitter (EUSART). See EUSART. Equations A/D Acquisition Time .................................................228 A/D Minimum Charging Time ....................................228 Calculating the Minimum Required Acquisition Time................................................228 Errata.....................................................................................6 EUSART Asynchronous Mode .................................................211 12-Bit Break Transmit and Receive ..................216 Associated Registers, Receive .........................214 Associated Registers, Transmit ........................212 Auto-Wake-up on Sync Break...........................214 Receiver ............................................................213 Setting up 9-Bit Mode with Address Detect .........................................213 Transmitter ........................................................211 Baud Rate Generator Operation in Power-Managed Mode .................205 Baud Rate Generator (BRG) .....................................205 Associated Registers ........................................206 Auto-Baud Rate Detect .....................................209 Baud Rate Error, Calculating ............................206 Baud Rates, Asynchronous Modes...................207 High Baud Rate Select (BRGH Bit)...................205 Sampling ...........................................................205 DS39631E-page 399 Synchronous Master Mode ....................................... 217 Associated Registers, Receive ......................... 219 Associated Registers, Transmit ........................ 218 Reception.......................................................... 219 Transmission .................................................... 217 Synchronous Slave Mode ......................................... 220 Associated Registers, Receive ......................... 221 Associated Registers, Transmit ........................ 220 Reception.......................................................... 221 Transmission .................................................... 220 Extended Instruction Set ADDFSR ................................................................... 310 ADDULNK................................................................. 310 and Using MPLAB IDE Tools.................................... 316 CALLW ..................................................................... 311 Considerations for Use ............................................. 314 MOVSF ..................................................................... 311 MOVSS..................................................................... 312 PUSHL ...................................................................... 312 SUBFSR ................................................................... 313 SUBULNK................................................................. 313 Syntax....................................................................... 309 External Clock Input............................................................ 24 F Fail-Safe Clock Monitor............................................. 249, 261 Exiting Operation ...................................................... 261 Interrupts in Power-Managed Modes........................ 262 POR or Wake from Sleep ......................................... 262 WDT During Oscillator Failure .................................. 261 Fast Register Stack............................................................. 56 Firmware Instructions........................................................ 267 Flash Program Memory ...................................................... 73 Associated Registers .................................................. 81 Control Registers ........................................................ 74 EECON1 and EECON2 ...................................... 74 TABLAT (Table Latch) Register.......................... 76 TBLPTR (Table Pointer) Register....................... 76 Erase Sequence ......................................................... 78 Erasing........................................................................ 78 Operation During Code-Protect .................................. 81 Reading ...................................................................... 77 Table Pointer Boundaries Based on Operation......................... 76 Table Pointer Boundaries ........................................... 76 Table Reads and Table Writes ................................... 73 Write Sequence .......................................................... 79 Writing To ................................................................... 79 Protection Against Spurious Writes .................... 81 Unexpected Termination..................................... 81 Write Verify ......................................................... 81 FSCM. See Fail-Safe Clock Monitor. G General Call Address Support .......................................... 184 GOTO ............................................................................... 288 H Hardware Multiplier ............................................................. 89 Introduction ................................................................. 89 Operation .................................................................... 89 Performance Comparison ........................................... 89 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 High/Low-Voltage Detect Applications............................................................... 246 Associated Registers ................................................ 247 Characteristics .......................................................... 339 Current Consumption ................................................ 245 Effects of a Reset...................................................... 247 Operation .................................................................. 244 During Sleep ..................................................... 247 Setup......................................................................... 245 Start-up Time ............................................................ 245 Typical Application .................................................... 246 HLVD. See High/Low-Voltage Detect. I I/O Ports ............................................................................ 105 I2C Mode (MSSP) Acknowledge Sequence Timing................................ 194 Baud Rate Generator ................................................ 187 Bus Collision During a Repeated Start Condition ................... 198 During a Stop Condition.................................... 199 Clock Arbitration........................................................ 188 Clock Stretching ........................................................ 180 10-Bit Slave Receive Mode (SEN = 1).............. 180 10-Bit Slave Transmit Mode.............................. 180 7-Bit Slave Receive Mode (SEN = 1)................ 180 7-Bit Slave Transmit Mode................................ 180 Clock Synchronization and the CKP bit (SEN = 1) ............................................. 181 Effects of a Reset...................................................... 195 General Call Address Support .................................. 184 I2C Clock Rate w/BRG .............................................. 187 Master Mode ............................................................. 185 Operation .......................................................... 186 Reception.......................................................... 191 Repeated Start Condition Timing...................... 190 Start Condition Timing ...................................... 189 Transmission..................................................... 191 Multi-Master Communication, Bus Collision and Arbitration .................................... 195 Multi-Master Mode .................................................... 195 Operation .................................................................. 174 Read/Write Bit Information (R/W Bit) ................ 174, 175 Registers................................................................... 170 Serial Clock (RC3/SCK/SCL) .................................... 175 Slave Mode ............................................................... 174 Addressing ........................................................ 174 Reception.......................................................... 175 Transmission..................................................... 175 Sleep Operation ........................................................ 195 Stop Condition Timing............................................... 194 ID Locations .............................................................. 249, 266 INCF.................................................................................. 288 INCFSZ ............................................................................. 289 In-Circuit Debugger ........................................................... 266 In-Circuit Serial Programming (ICSP) ....................... 249, 266 Indexed Literal Offset Addressing and Standard PIC18 Instructions .............................. 314 Indexed Literal Offset Mode .............................................. 314 Indirect Addressing ............................................................. 69 INFSNZ ............................................................................. 289 Initialization Conditions for all Registers ....................... 49-52 Instruction Cycle.................................................................. 57 Clocking Scheme ........................................................ 57 Instruction Flow/Pipelining .................................................. 57 Instruction Set ................................................................... 267 DS39631E-page 400 ADDLW..................................................................... 273 ADDWF..................................................................... 273 ADDWF (Indexed Literal Offset Mode) ..................... 315 ADDWFC .................................................................. 274 ANDLW..................................................................... 274 ANDWF..................................................................... 275 BC............................................................................. 275 BCF .......................................................................... 276 BN............................................................................. 276 BNC .......................................................................... 277 BNN .......................................................................... 277 BNOV ....................................................................... 278 BNZ .......................................................................... 278 BOV .......................................................................... 281 BRA .......................................................................... 279 BSF........................................................................... 279 BSF (Indexed Literal Offset Mode) ........................... 315 BTFSC ...................................................................... 280 BTFSS ...................................................................... 280 BTG .......................................................................... 281 BZ ............................................................................. 282 CALL......................................................................... 282 CLRF ........................................................................ 283 CLRWDT .................................................................. 283 COMF ....................................................................... 284 CPFSEQ ................................................................... 284 CPFSGT ................................................................... 285 CPFSLT .................................................................... 285 DAW ......................................................................... 286 DCFSNZ ................................................................... 287 DECF ........................................................................ 286 DECFSZ ................................................................... 287 Extended Instruction Set .......................................... 309 General Format......................................................... 269 GOTO ....................................................................... 288 INCF ......................................................................... 288 INCFSZ..................................................................... 289 INFSNZ..................................................................... 289 IORLW ...................................................................... 290 IORWF...................................................................... 290 LFSR ........................................................................ 291 MOVF ....................................................................... 291 MOVFF ..................................................................... 292 MOVLB ..................................................................... 292 MOVLW .................................................................... 293 MOVWF .................................................................... 293 MULLW..................................................................... 294 MULWF..................................................................... 294 NEGF........................................................................ 295 NOP .......................................................................... 295 Opcode Field Descriptions........................................ 268 POP .......................................................................... 296 PUSH........................................................................ 296 RCALL ...................................................................... 297 RESET...................................................................... 297 RETFIE ..................................................................... 298 RETLW ..................................................................... 298 RETURN................................................................... 299 RLCF ........................................................................ 299 RLNCF...................................................................... 300 RRCF........................................................................ 300 RRNCF ..................................................................... 301 SETF ........................................................................ 301 SETF (Indexed Literal Offset Mode) ......................... 315 SLEEP ...................................................................... 302 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 Standard Instructions ................................................267 SUBFWB...................................................................302 SUBLW .....................................................................303 SUBWF .....................................................................303 SUBWFB...................................................................304 SWAPF .....................................................................304 TBLRD ......................................................................305 TBLWT ......................................................................306 TSTFSZ.....................................................................307 XORLW .....................................................................307 XORWF.....................................................................308 INTCON Registers ........................................................ 93-95 Inter-Integrated Circuit. See I2C. Internal Oscillator Block.......................................................26 Adjustment ..................................................................26 INTIO Modes...............................................................26 INTOSC Frequency Drift .............................................26 INTOSC Output Frequency.........................................26 OSCTUNE Register ....................................................26 PLL in INTOSC Modes................................................26 Internal RC Oscillator Use with WDT ...........................................................258 Internet Address ................................................................407 Interrupt Sources...............................................................249 A/D Conversion Complete.........................................227 Capture Complete (CCP) ..........................................141 Compare Complete (CCP) ........................................142 Interrupt-on-Change (RB7:RB4) ...............................108 INTx Pin ....................................................................103 PORTB, Interrupt-on-Change ...................................103 TMR0 ........................................................................103 TMR0 Overflow .........................................................125 TMR1 Overflow .........................................................127 TMR2 to PR2 Match (PWM) ............................. 144, 149 TMR3 Overflow ................................................. 135, 137 Interrupts .............................................................................91 Interrupts, Flag Bits Interrupt-on-Change (RB7:RB4) Flag (RBIF Bit) ..........................................................108 INTOSC, INTRC. See Internal Oscillator Block. IORLW...............................................................................290 IORWF ..............................................................................290 IPR Registers ............................................................100-101 L LFSR .................................................................................291 Low-Voltage ICSP Programming. See Single-Supply ICSP Programming M Master Clear (MCLR) ..........................................................43 Master Synchronous Serial Port (MSSP). See MSSP. Memory Organization ..........................................................53 Data Memory...............................................................59 Program Memory ........................................................53 Memory Programming Requirements ...............................337 Microchip Internet Web Site ..............................................407 Migration from High-End to Enhanced Devices ................396 Migration from Mid-Range to Enhanced Devices..............396 MOVF ................................................................................291 MOVFF..............................................................................292 MOVLB..............................................................................292 MOVLW.............................................................................293 MOVSF..............................................................................311 MOVSS .............................................................................312 MOVWF.............................................................................293 DS39631E-page 401 MPLAB ASM30 Assembler, Linker, Librarian ................... 318 MPLAB ICD 2 In-Circuit Debugger ................................... 319 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator .................................... 319 MPLAB Integrated Development Environment Software .............................................. 317 MPLAB PM3 Device Programmer .................................... 319 MPLAB REAL ICE In-Circuit Emulator System................. 319 MPLINK Object Linker/MPLIB Object Librarian ................ 318 MSSP ACK Pulse ........................................................ 174, 175 Control Registers (general)....................................... 161 I2C Mode. See I2C Mode. Module Overview ...................................................... 161 SPI Master/Slave Connection ................................... 165 SPI Mode. See SPI Mode. SSPBUF Register ..................................................... 166 SSPSR Register ....................................................... 166 MULLW ............................................................................. 294 MULWF............................................................................. 294 N NEGF ................................................................................ 295 NOP .................................................................................. 295 O Oscillator Configuration....................................................... 23 EC............................................................................... 23 ECIO ........................................................................... 23 HS............................................................................... 23 HSPLL ........................................................................ 23 Internal Oscillator Block .............................................. 26 INTIO1 ........................................................................ 23 INTIO2 ........................................................................ 23 LP ............................................................................... 23 RC............................................................................... 23 RCIO ........................................................................... 23 XT ............................................................................... 23 Oscillator Selection ........................................................... 249 Oscillator Start-up Timer (OST) .................................... 31, 45 Oscillator Switching............................................................. 28 Oscillator Transitions .......................................................... 29 Oscillator, Timer1...................................................... 127, 137 Oscillator, Timer3.............................................................. 135 P Packaging Information ...................................................... 383 Details....................................................................... 385 Marking ..................................................................... 383 Parallel Slave Port (PSP).......................................... 114, 120 Associated Registers ................................................ 121 CS (Chip Select) ....................................................... 120 PORTD ..................................................................... 120 RD (Read Input)........................................................ 120 Select (PSPMODE Bit) ..................................... 114, 120 WR (Write Input) ....................................................... 120 PICSTART Plus Development Programmer ..................... 320 PIE Registers ................................................................ 98-99 Pin Functions MCLR/VPP/RE3 .................................................... 12, 16 OSC1/CLKI/RA7 ................................................... 12, 16 OSC2/CLKO/RA6 ................................................. 12, 16 RA0/AN0 ............................................................... 13, 17 RA1/AN1 ............................................................... 13, 17 RA2/AN2/VREF-/CVREF ......................................... 13, 17 RA3/AN3/VREF+.................................................... 13, 17 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 RA4/T0CKI/C1OUT............................................... 13, 17 RA5/AN4/SS/HLVDIN/C2OUT .............................. 13, 17 RB0/INT0/FLT0/AN12 ........................................... 14, 18 RB1/INT1/AN10 .................................................... 14, 18 RB2/INT2/AN8 ...................................................... 14, 18 RB3/AN9/CCP2 .................................................... 14, 18 RB4/KBI0/AN11 .................................................... 14, 18 RB5/KBI1/PGM ..................................................... 14, 18 RB6/KBI2/PGC ..................................................... 14, 18 RB7/KBI3/PGD ..................................................... 14, 18 RC0/T1OSO/T13CKI ............................................ 15, 19 RC1/T1OSI/CCP2 ................................................. 15, 19 RC2/CCP1 .................................................................. 15 RC2/CCP1/P1A .......................................................... 19 RC3/SCK/SCL ...................................................... 15, 19 RC4/SDI/SDA ....................................................... 15, 19 RC5/SDO .............................................................. 15, 19 RC6/TX/CK ........................................................... 15, 19 RC7/RX/DT ........................................................... 15, 19 RD0/PSP0................................................................... 20 RD1/PSP1................................................................... 20 RD2/PSP2................................................................... 20 RD3/PSP3................................................................... 20 RD4/PSP4................................................................... 20 RD5/PSP5/P1B........................................................... 20 RD6/PSP6/P1C........................................................... 20 RD7/PSP7/P1D........................................................... 20 RE0/RD/AN5 ............................................................... 21 RE1/WR/AN6 .............................................................. 21 RE2/CS/AN7 ............................................................... 21 VDD........................................................................ 15, 21 VSS ........................................................................ 15, 21 Pinout I/O Descriptions PIC18F2420/2520....................................................... 12 PIC18F4420/4520....................................................... 16 PIR Registers ................................................................ 96-97 PLL Frequency Multiplier .................................................... 25 HSPLL Oscillator Mode............................................... 25 Use with INTOSC........................................................ 25 POP................................................................................... 296 POR. See Power-on Reset. PORTA Associated Registers ................................................ 107 LATA Register........................................................... 105 PORTA Register ....................................................... 105 TRISA Register ......................................................... 105 PORTB Associated Registers ................................................ 110 LATB Register........................................................... 108 PORTB Register ....................................................... 108 RB7:RB4 Interrupt-on-Change Flag (RBIF Bit) .......................................................... 108 TRISB Register ......................................................... 108 PORTC Associated Registers ................................................ 113 LATC Register .......................................................... 111 PORTC Register ....................................................... 111 RC3/SCK/SCL Pin .................................................... 175 TRISC Register ......................................................... 111 PORTD Associated Registers ................................................ 116 LATD Register .......................................................... 114 Parallel Slave Port (PSP) Function ........................... 114 PORTD Register ....................................................... 114 TRISD Register ......................................................... 114 DS39631E-page 402 PORTE Associated Registers ................................................ 119 LATE Register .......................................................... 117 PORTE Register ....................................................... 117 PSP Mode Select (PSPMODE Bit) ........................... 114 TRISE Register......................................................... 117 Power-Managed Modes...................................................... 33 and A/D Operation .................................................... 230 and EUSART Operation ........................................... 205 and Multiple Sleep Commands................................... 34 and PWM Operation ................................................. 159 and SPI Operation .................................................... 169 Clock Transitions and Status Indicators ..................... 34 Effects on Clock Sources............................................ 31 Entering ...................................................................... 33 Exiting Idle and Sleep Modes ..................................... 39 by Interrupt ......................................................... 39 by Reset ............................................................. 39 by WDT Time-out ............................................... 39 Without a Start-up Delay .................................... 40 Idle Modes .................................................................. 37 PRI_IDLE............................................................ 38 RC_IDLE ............................................................ 39 SEC_IDLE .......................................................... 38 Run Modes ................................................................. 34 PRI_RUN............................................................ 34 RC_RUN............................................................. 35 SEC_RUN .......................................................... 34 Selecting ..................................................................... 33 Sleep Mode ................................................................ 37 Summary (table) ......................................................... 33 Power-on Reset (POR)....................................................... 43 Power-up Timer (PWRT) ............................................ 45 Time-out Sequence .................................................... 45 Power-up Delays ................................................................ 31 Power-up Timer (PWRT) .................................................... 31 Prescaler Timer2 ...................................................................... 150 Prescaler, Timer0 ............................................................. 125 Prescaler, Timer2 ............................................................. 145 PRI_IDLE Mode.................................................................. 38 PRI_RUN Mode .................................................................. 34 Program Counter ................................................................ 54 PCL, PCH and PCU Registers ................................... 54 PCLATH and PCLATU Registers ............................... 54 Program Memory and Extended Instruction Set ..................................... 72 Code Protection ........................................................ 264 Instructions ................................................................. 58 Two-Word ........................................................... 58 Interrupt Vector ........................................................... 53 Look-up Tables ........................................................... 56 Map and Stack (diagram) ........................................... 53 Reset Vector ............................................................... 53 Program Verification and Code Protection ....................... 263 Associated Registers ................................................ 263 Programming, Device Instructions.................................... 267 PSP. See Parallel Slave Port. Pulse-Width Modulation. See PWM (CCP Module) and PWM (ECCP Module). PUSH................................................................................ 296 PUSH and POP Instructions............................................... 55 PUSHL.............................................................................. 312 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 PWM (CCP Module) Associated Registers ................................................146 Auto-Shutdown (CCP1 Only) ....................................145 Duty Cycle.................................................................144 Example Frequencies/Resolutions............................145 Period ........................................................................144 Setup for PWM Operation .........................................145 TMR2 to PR2 Match..................................................144 PWM (ECCP Module) .......................................................149 CCPR1H:CCPR1L Registers ....................................149 Direction Change in Full-Bridge Output Mode .....................................................154 Duty Cycle.................................................................150 Effects of a Reset......................................................159 Enhanced PWM Auto-Shutdown...............................156 Example Frequencies/Resolutions............................150 Full-Bridge Mode.......................................................153 Full-Bridge Output Mode Application Example .........154 Half-Bridge Mode ......................................................152 Half-Bridge Output Mode Applications Example .......152 Operation in Power-Managed Modes .......................159 Operation with Fail-Safe Clock Monitor.....................159 Output Configurations ...............................................150 Output Relationships (Active-High) ...........................151 Output Relationships (Active-Low) ............................151 Period ........................................................................149 Programmable Dead-Band Delay .............................156 Setup for PWM Operation .........................................159 Start-up Considerations ............................................158 TMR2 to PR2 Match..................................................149 Q Q Clock...................................................................... 145, 150 R RAM. See Data Memory. RBIF Bit .............................................................................108 RC Oscillator .......................................................................25 RCIO Oscillator Mode .................................................25 RC_IDLE Mode ...................................................................39 RC_RUN Mode ...................................................................35 RCALL...............................................................................297 RCON Register Bit Status During Initialization .....................................48 Reader Response .............................................................408 Register File ........................................................................62 Register File Summary.................................................. 64-66 Registers ADCON0 (A/D Control 0) ..........................................223 ADCON1 (A/D Control 1) ..........................................224 ADCON2 (A/D Control 2) ..........................................225 BAUDCON (Baud Rate Control) ...............................204 CCP1CON (ECCP Control, 40/44-Pin Devices)............................................147 CCPxCON (CCPx Control, 28-Pin Devices) .............139 CMCON (Comparator Control)..................................233 CONFIG1H (Configuration 1 High) ...........................250 CONFIG2H (Configuration 2 High) ...........................252 CONFIG2L (Configuration 2 Low) .............................251 CONFIG3H (Configuration 3 High) ...........................253 CONFIG4L (Configuration 4 Low) .............................253 CONFIG5H (Configuration 5 High) ...........................254 CONFIG5L (Configuration 5 Low) .............................254 CONFIG6H (Configuration 6 High) ...........................255 CONFIG6L (Configuration 6 Low) .............................255 CONFIG7H (Configuration 7 High) ...........................256 DS39631E-page 403 CONFIG7L (Configuration 7 Low) ............................ 256 CVRCON (Comparator Voltage Reference Control) ........................................... 239 DEVID1 (Device ID 1) ............................................... 257 DEVID2 (Device ID 2) ............................................... 257 ECCP1AS (ECCP Auto-Shutdown Control) ............. 157 EECON1 (EEPROM Control 1) ............................ 75, 84 HLVDCON (High/Low-Voltage Detect Control) ........ 243 INTCON (Interrupt Control)......................................... 93 INTCON2 (Interrupt Control 2).................................... 94 INTCON3 (Interrupt Control 3).................................... 95 IPR1 (Peripheral Interrupt Priority 1) ........................ 100 IPR2 (Peripheral Interrupt Priority 2) ........................ 101 OSCCON (Oscillator Control) ..................................... 30 OSCTUNE (Oscillator Tuning) .................................... 27 PIE1 (Peripheral Interrupt Enable 1)........................... 98 PIE2 (Peripheral Interrupt Enable 2)........................... 99 PIR1 (Peripheral Interrupt Request (Flag) 1) .............. 96 PIR2 (Peripheral Interrupt Request (Flag) 2) .............. 97 PWM1CON (PWM Dead-Band Delay) ..................... 156 RCON (Reset Control) ........................................ 42, 102 RCSTA (Receive Status and Control) ...................... 203 SSPCON1 (MSSP Control 1, I2C Mode) .................. 172 SSPCON1 (MSSP Control 1, SPI Mode).................. 163 SSPCON2 (MSSP Control 2, I2C Mode) .................. 173 SSPSTAT (MSSP Status, I2C Mode) ....................... 171 SSPSTAT (MSSP Status, SPI Mode) ....................... 162 STATUS...................................................................... 67 STKPTR (Stack Pointer) ............................................. 55 T0CON (Timer0 Control) .......................................... 123 T1CON (Timer1 Control) .......................................... 127 T2CON (Timer2 Control) .......................................... 133 T3CON (Timer3 Control) .......................................... 135 TRISE (PORTE/PSP Control)................................... 118 TXSTA (Transmit Status and Control) ...................... 202 WDTCON (Watchdog Timer Control) ....................... 259 RESET .............................................................................. 297 Reset State of Registers ..................................................... 48 Resets......................................................................... 41, 249 Brown-out Reset (BOR) ............................................ 249 Oscillator Start-up Timer (OST) ................................ 249 Power-on Reset (POR) ............................................. 249 Power-up Timer (PWRT) .......................................... 249 RETFIE ............................................................................. 298 RETLW ............................................................................. 298 RETURN ........................................................................... 299 Return Address Stack ......................................................... 54 Return Stack Pointer (STKPTR) ......................................... 55 Revision History ................................................................ 395 RLCF................................................................................. 299 RLNCF .............................................................................. 300 RRCF ................................................................................ 300 RRNCF ............................................................................. 301 S SCK................................................................................... 161 SDI .................................................................................... 161 SDO .................................................................................. 161 SEC_IDLE Mode................................................................. 38 SEC_RUN Mode................................................................. 34 Serial Clock, SCK ............................................................. 161 Serial Data In (SDI)........................................................... 161 Serial Data Out (SDO) ...................................................... 161 Serial Peripheral Interface. See SPI Mode. SETF................................................................................. 301 Slave Select (SS).............................................................. 161 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 Slave Select Synchronization............................................ 167 SLEEP............................................................................... 302 Sleep OSC1 and OSC2 Pin States ....................................... 31 Software Simulator (MPLAB SIM)..................................... 318 Special Event Trigger. See Compare (ECCP Mode). Special Event Trigger. See Compare (ECCP Module). Special Features of the CPU............................................. 249 Special Function Registers Map ............................................................................. 63 SPI Mode (MSSP) Associated Registers ................................................ 169 Bus Mode Compatibility ............................................ 169 Effects of a Reset...................................................... 169 Enabling SPI I/O ....................................................... 165 Master Mode ............................................................. 166 Master/Slave Connection .......................................... 165 Operation .................................................................. 164 Operation in Power-Managed Modes ....................... 169 Serial Clock............................................................... 161 Serial Data In ............................................................ 161 Serial Data Out ......................................................... 161 Slave Mode ............................................................... 167 Slave Select .............................................................. 161 Slave Select Synchronization ................................... 167 SPI Clock .................................................................. 166 Typical Connection ................................................... 165 SS ..................................................................................... 161 SSPOV.............................................................................. 191 SSPOV Status Flag........................................................... 191 SSPSTAT Register R/W Bit .............................................................. 174, 175 Stack Full/Underflow Resets ............................................... 56 STATUS Register................................................................ 67 SUBFSR............................................................................ 313 SUBFWB........................................................................... 302 SUBLW ............................................................................. 303 SUBULNK ......................................................................... 313 SUBWF ............................................................................. 303 SUBWFB........................................................................... 304 SWAPF ............................................................................. 304 T Table Pointer Operations with TBLRD and TBLWT .................................................... 76 Table Reads/Table Writes................................................... 56 TBLRD .............................................................................. 305 TBLWT .............................................................................. 306 Time-out in Various Situations (table) ................................. 45 Timer0 ............................................................................... 123 Associated Registers ................................................ 125 Operation .................................................................. 124 Overflow Interrupt ..................................................... 125 Prescaler ................................................................... 125 Prescaler Assignment (PSA Bit) ............................... 125 Prescaler Select (T0PS2:T0PS0 Bits) ...................... 125 Prescaler. See Prescaler, Timer0. Reads and Writes in 16-Bit Mode ............................. 124 Source Edge Select (T0SE Bit)................................. 124 Source Select (T0CS Bit) .......................................... 124 Switching Prescaler Assignment............................... 125 DS39631E-page 404 Timer1............................................................................... 127 16-Bit Read/Write Mode ........................................... 129 Associated Registers ................................................ 132 Considerations in Asynchronous Counter Mode................................................... 131 Interrupt .................................................................... 130 Operation .................................................................. 128 Oscillator........................................................... 127, 129 Oscillator Layout Considerations .............................. 130 Overflow Interrupt ..................................................... 127 Resetting, Using the CCP Special Event Trigger .................................................... 130 Special Event Trigger (ECCP) .................................. 148 TMR1H Register ....................................................... 127 TMR1L Register........................................................ 127 Use as a Real-Time Clock ........................................ 130 Timer2............................................................................... 133 Associated Registers ................................................ 134 Interrupt .................................................................... 134 Operation .................................................................. 133 Output ....................................................................... 134 PR2 Register .................................................... 144, 149 TMR2 to PR2 Match Interrupt........................... 144, 149 Timer3............................................................................... 135 16-Bit Read/Write Mode ........................................... 137 Associated Registers ................................................ 137 Operation .................................................................. 136 Oscillator........................................................... 135, 137 Overflow Interrupt ............................................. 135, 137 Special Event Trigger (CCP) .................................... 137 TMR3H Register ....................................................... 135 TMR3L Register........................................................ 135 Timing Diagrams A/D Conversion......................................................... 360 Acknowledge Sequence ........................................... 194 Asynchronous Reception.......................................... 214 Asynchronous Transmission..................................... 212 Asynchronous Transmission (Back to Back) ............ 212 Automatic Baud Rate Calculation ............................. 210 Auto-Wake-up Bit (WUE) During Normal Operation ............................................. 215 Auto-Wake-up Bit (WUE) During Sleep .................... 215 Baud Rate Generator with Clock Arbitration............. 188 BRG Overflow Sequence.......................................... 210 BRG Reset Due to SDA Arbitration During Start Condition ...................................... 197 Brown-out Reset (BOR)............................................ 345 Bus Collision During a Repeated Start Condition (Case 1) ................................... 198 Bus Collision During a Repeated Start Condition (Case 2) ................................... 198 Bus Collision During a Start Condition (SCL = 0) .......................................... 197 Bus Collision During a Stop Condition (Case 1)............................................ 199 Bus Collision During a Stop Condition (Case 2)............................................ 199 Bus Collision During Start Condition (SDA only) ........................................ 196 Bus Collision for Transmit and Acknowledge ........... 195 Capture/Compare/PWM (All CCP Modules)............. 347 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 CLKO and I/O............................................................344 Clock Synchronization...............................................181 Clock/Instruction Cycle................................................57 EUSART Synchronous Receive (Master/Slave)...................................................359 EUSART Synchronous Transmission (Master/Slave)...................................................358 Example SPI Master Mode (CKE = 0).......................349 Example SPI Master Mode (CKE = 1).......................350 Example SPI Slave Mode (CKE = 0).........................351 Example SPI Slave Mode (CKE = 1).........................353 External Clock (All Modes Except PLL) ....................342 Fail-Safe Clock Monitor (FSCM) ...............................262 First Start Bit Timing..................................................189 Full-Bridge PWM Output ...........................................153 Half-Bridge PWM Output...........................................152 High/Low-Voltage Detect Characteristics..................339 High-Voltage Detect Operation (VDIRMAG = 1) .......246 I2C Bus Data .............................................................354 I2C Bus Start/Stop Bits..............................................354 I2C Master Mode (7 or 10-Bit Transmission).............192 I2C Master Mode (7-Bit Reception) ...........................193 I2C Slave Mode (10-Bit Reception, SEN = 0)............178 I2C Slave Mode (10-Bit Reception, SEN = 1)............183 I2C Slave Mode (10-Bit Transmission) ......................179 I2C Slave Mode (7-Bit Reception, SEN = 0)..............176 I2C Slave Mode (7-Bit Reception, SEN = 1)..............182 I2C Slave Mode (7-Bit Transmission) ........................177 I2C Slave Mode General Call Address Sequence (7 or 10-Bit Addressing Mode) .........184 I2C Stop Condition Receive or Transmit Mode .........194 Low-Voltage Detect Operation (VDIRMAG = 0)........245 Master SSP I2C Bus Data .........................................356 Master SSP I2C Bus Start/Stop Bits..........................356 Parallel Slave Port (PIC18F4420/4520) ....................348 Parallel Slave Port (PSP) Read ................................121 Parallel Slave Port (PSP) Write.................................121 PWM Auto-Shutdown (PRSEN = 0, Auto-Restart Disabled)......................................158 PWM Auto-Shutdown (PRSEN = 1, Auto-Restart Enabled).......................................158 PWM Direction Change.............................................155 PWM Direction Change at Near 100% Duty Cycle...............................................155 PWM Output..............................................................144 Repeated Start Condition..........................................190 Reset, Watchdog Timer, Oscillator Start-up Timer, Power-up Timer .....................................345 Send Break Character Sequence .............................216 Slave Synchronization...............................................167 Slow Rise Time (MCLR Tied to VDD, VDD Rise > TPWRT) .............................................47 SPI Mode (Master Mode) ..........................................166 SPI Mode (Slave Mode, CKE = 0).............................168 SPI Mode (Slave Mode, CKE = 1).............................168 Synchronous Reception (Master Mode, SREN)........219 Synchronous Transmission .......................................217 Synchronous Transmission (Through TXEN) ...........218 Time-out Sequence on POR w/PLL Enabled (MCLR Tied to VDD) ............................................47 Time-out Sequence on Power-up (MCLR Not Tied to VDD, Case 1) ........................46 Time-out Sequence on Power-up (MCLR Not Tied to VDD, Case 2) ........................46 DS39631E-page 405 Time-out Sequence on Power-up (MCLR Tied to VDD, VDD Rise < TPWRT) ............ 46 Timer0 and Timer1 External Clock ........................... 346 Transition for Entry to Idle Mode................................. 38 Transition for Entry to SEC_RUN Mode ..................... 35 Transition for Entry to Sleep Mode ............................. 37 Transition for Two-Speed Start-up (INTOSC to HSPLL) ......................................... 260 Transition for Wake from Idle to Run Mode ........................................................... 38 Transition for Wake from Sleep (HSPLL) ................... 37 Transition from RC_RUN Mode to PRI_RUN Mode .................................................. 36 Transition from SEC_RUN Mode to PRI_RUN Mode (HSPLL) ................................... 35 Transition to RC_RUN Mode ...................................... 36 Timing Diagrams and Specifications................................. 342 A/D Conversion Requirements ................................. 360 Capture/Compare/PWM (CCP) Requirements ................................................... 347 CLKO and I/O Requirements .................................... 344 EUSART Synchronous Receive Requirements ................................................... 359 EUSART Synchronous Transmission Requirements ................................................... 358 Example SPI Mode Requirements (Master Mode, CKE = 0) ................................... 349 Example SPI Mode Requirements (Master Mode, CKE = 1) ................................... 350 Example SPI Mode Requirements (Slave Mode, CKE = 0) ..................................... 352 Example SPI Mode Requirements (Slave Mode, CKE = 1) ..................................... 353 External Clock Requirements ................................... 342 I2C Bus Data Requirements (Slave Mode) ............... 355 Master SSP I2C Bus Data Requirements ................................................... 357 Master SSP I2C Bus Start/Stop Bits Requirements ................................................... 356 Parallel Slave Port Requirements (PIC18F4420/4520) .......................................... 348 PLL Clock ................................................................. 343 Reset, Watchdog Timer, Oscillator Start-up Timer, Power-up Timer and Brown-out Reset Requirements ......................................... 345 Timer0 and Timer1 External Clock Requirements ................................................... 346 Top-of-Stack Access........................................................... 54 TRISE Register PSPMODE Bit........................................................... 114 TSTFSZ ............................................................................ 307 Two-Speed Start-up.................................................. 249, 260 Two-Word Instructions Example Cases........................................................... 58 TXSTA Register BRGH Bit .................................................................. 205 V Voltage Reference Specifications ..................................... 338 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 W X Watchdog Timer (WDT) ............................................ 249, 258 Associated Registers ................................................ 259 Control Register ........................................................ 258 During Oscillator Failure ........................................... 261 Programming Considerations ................................... 258 WCOL ....................................................... 189, 190, 191, 194 WCOL Status Flag .................................... 189, 190, 191, 194 WWW Address.................................................................. 407 WWW, On-Line Support........................................................ 6 XORLW............................................................................. 307 XORWF ............................................................................ 308 DS39631E-page 406 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 THE MICROCHIP WEB SITE CUSTOMER SUPPORT Microchip provides online support via our WWW site at www.microchip.com. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information: Users of Microchip products can receive assistance through several channels: * Product Support - Data sheets and errata, application notes and sample programs, design resources, user's guides and hardware support documents, latest software releases and archived software * General Technical Support - Frequently Asked Questions (FAQ), technical support requests, online discussion groups, Microchip consultant program member listing * Business of Microchip - Product selector and ordering guides, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives * * * * * Distributor or Representative Local Sales Office Field Application Engineer (FAE) Technical Support Development Systems Information Line Customers should contact their distributor, representative or field application engineer (FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document. Technical support is available through the web site at: http://support.microchip.com CUSTOMER CHANGE NOTIFICATION SERVICE Microchip's customer notification service helps keep customers current on Microchip products. Subscribers will receive e-mail notification whenever there are changes, updates, revisions or errata related to a specified product family or development tool of interest. To register, access the Microchip web site at www.microchip.com, click on Customer Change Notification and follow the registration instructions. (c) 2008 Microchip Technology Inc. DS39631E-page 407 PIC18F2420/2520/4420/4520 READER RESPONSE It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150. Please list the following information, and use this outline to provide us with your comments about this document. To: Technical Publications Manager RE: Reader Response Total Pages Sent ________ From: Name Company Address City / State / ZIP / Country Telephone: (_______) _________ - _________ FAX: (______) _________ - _________ Application (optional): Would you like a reply? Y N Device: PIC18F2420/2520/4420/4520 Literature Number: DS39631E Questions: 1. What are the best features of this document? 2. How does this document meet your hardware and software development needs? 3. Do you find the organization of this document easy to follow? If not, why? 4. What additions to the document do you think would enhance the structure and subject? 5. What deletions from the document could be made without affecting the overall usefulness? 6. Is there any incorrect or misleading information (what and where)? 7. How would you improve this document? DS39631E-page 408 (c) 2008 Microchip Technology Inc. PIC18F2420/2520/4420/4520 PIC18F2420/2520/4420/4520 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 Device Temperature Range Package Pattern Examples: a) b) Device PIC18F2420/2520(1), PIC18F4420/4520(1), PIC18F2420/2520T(2), PIC18F4420/4520T(2); VDD range 4.2V to 5.5V PIC18LF2420/2520(1), PIC18LF4420/4520(1), PIC18LF2420/2520T(2), PIC18LF4420/4520T(2); VDD range 2.0V to 5.5V Temperature Range I E = = Package PT SO SP P ML = = = = = Pattern c) PIC18LF4520-I/P 301 = Industrial temp., PDIP package, Extended VDD limits, QTP pattern #301. PIC18LF2420-I/SO = Industrial temp., SOIC package, Extended VDD limits. PIC18F4420-I/P = Industrial temp., PDIP package, normal VDD limits. -40C to +85C (Industrial) -40C to +125C (Extended) TQFP (Thin Quad Flatpack) SOIC Skinny Plastic DIP PDIP QFN Note 1: 2: F = Standard Voltage Range LF = Wide Voltage Range T = in tape and reel TQFP packages only. QTP, SQTP, Code or Special Requirements (blank otherwise) (c) 2008 Microchip Technology Inc. Advance Information DS39631E-page 409 WORLDWIDE SALES AND SERVICE AMERICAS ASIA/PACIFIC ASIA/PACIFIC EUROPE Corporate Office 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-792-7200 Fax: 480-792-7277 Technical Support: http://support.microchip.com Web Address: www.microchip.com Asia Pacific Office Suites 3707-14, 37th Floor Tower 6, The Gateway Harbour City, Kowloon Hong Kong Tel: 852-2401-1200 Fax: 852-2401-3431 India - Bangalore Tel: 91-80-4182-8400 Fax: 91-80-4182-8422 India - New Delhi Tel: 91-11-4160-8631 Fax: 91-11-4160-8632 Austria - Wels Tel: 43-7242-2244-39 Fax: 43-7242-2244-393 Denmark - Copenhagen Tel: 45-4450-2828 Fax: 45-4485-2829 India - Pune Tel: 91-20-2566-1512 Fax: 91-20-2566-1513 France - Paris Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 Japan - Yokohama Tel: 81-45-471- 6166 Fax: 81-45-471-6122 Germany - Munich Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Korea - Daegu Tel: 82-53-744-4301 Fax: 82-53-744-4302 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Atlanta Duluth, GA Tel: 678-957-9614 Fax: 678-957-1455 Boston Westborough, MA Tel: 774-760-0087 Fax: 774-760-0088 Chicago Itasca, IL Tel: 630-285-0071 Fax: 630-285-0075 Dallas Addison, TX Tel: 972-818-7423 Fax: 972-818-2924 Detroit Farmington Hills, MI Tel: 248-538-2250 Fax: 248-538-2260 Kokomo Kokomo, IN Tel: 765-864-8360 Fax: 765-864-8387 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 Santa Clara Santa Clara, CA Tel: 408-961-6444 Fax: 408-961-6445 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 China - Beijing Tel: 86-10-8528-2100 Fax: 86-10-8528-2104 China - Chengdu Tel: 86-28-8665-5511 Fax: 86-28-8665-7889 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 China - Nanjing Tel: 86-25-8473-2460 Fax: 86-25-8473-2470 Malaysia - Kuala Lumpur Tel: 60-3-6201-9857 Fax: 60-3-6201-9859 China - Qingdao Tel: 86-532-8502-7355 Fax: 86-532-8502-7205 Malaysia - Penang Tel: 60-4-227-8870 Fax: 60-4-227-4068 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 Philippines - Manila Tel: 63-2-634-9065 Fax: 63-2-634-9069 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 Taiwan - Hsin Chu Tel: 886-3-572-9526 Fax: 886-3-572-6459 China - Wuhan Tel: 86-27-5980-5300 Fax: 86-27-5980-5118 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 China - Xiamen Tel: 86-592-2388138 Fax: 86-592-2388130 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 China - Xian Tel: 86-29-8833-7252 Fax: 86-29-8833-7256 Thailand - Bangkok Tel: 66-2-694-1351 Fax: 66-2-694-1350 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 Spain - Madrid Tel: 34-91-708-08-90 Fax: 34-91-708-08-91 UK - Wokingham Tel: 44-118-921-5869 Fax: 44-118-921-5820 China - Zhuhai Tel: 86-756-3210040 Fax: 86-756-3210049 01/02/08 DS39631E-page 410 (c) 2008 Microchip Technology Inc.