PIC16F785 Data Sheet 20-Pin Flash-Based, 8-Bit CMOS Microcontroller with Two-Phase Asynchronous Feedback PWM Dual High-Speed Comparators and Dual Operational Amplifiers © 2005 Microchip Technology Inc. Preliminary DS41249B 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in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates.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’s products as critical components in life support systems is not authorized except with express written approval by Microchip. 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, microID, MPLAB, PIC, PICmicro, PICSTART, PRO MATE, PowerSmart, rfPIC, and SmartShunt are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB, PICMASTER, 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, dsPICDEM, dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, Linear Active Thermistor, MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM, PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo, PowerMate, PowerTool, rfLAB, rfPICDEM, Select Mode, Smart Serial, SmartTel, Total Endurance and WiperLock 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. © 2005, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received ISO/TS-16949:2002 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona and Mountain View, California in October 2003. The Company’s quality system processes and procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. DS41249B-page ii Preliminary © 2005 Microchip Technology Inc. PIC16F785 20-Pin Flash-Based 8-Bit CMOS Microcontroller High-Performance RISC CPU: Peripheral Features: • Only 35 instructions to learn: - All single-cycle instructions except branches • Operating speed: - DC – 20 MHz oscillator/clock input - DC – 200 ns instruction cycle • Interrupt capability • 8-level deep hardware stack • Direct, Indirect and Relative Addressing modes • High-speed Comparator module with: - Two independent analog comparators - Programmable on-chip voltage reference (CVREF) module (% of VDD) - 1.2V band gap voltage reference - Comparator inputs and outputs externally accessible - < 40 ns propagation delay - 2 mv offset, typical • Operational Amplifier module with 2 independent op amps: - 3 MHz GBWP, typical - All I/O pins externally accessible • Two-Phase Asynchronous Feedback PWM module: - Complementary output with programmable dead band delay - Infinite resolution analog duty cycle - Sync Output/Input for multi-phase PWM - FOSC/2 maximum PWM frequency • A/D Converter: - 10-bit resolution and 14 channels (2 internal) • 17 I/O pins and 1 input-only pin: - High-current source/sink for direct LED drive - Interrupt-on-pin change - Individually programmable weak pull-ups • Timer0: 8-bit timer/counter with 8-bit programmable prescaler • Enhanced Timer1: - 16-bit timer/counter with prescaler - External gate Input mode - Option to use OSC1 and OSC2 in LP mode as Timer1 oscillator, if INTOSC mode selected • Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler • Capture, Compare, PWM module: - 16-bit Capture, max resolution 12.5 ns - Compare, max resolution 200 ns - 10-bit PWM with 1 output channel, max frequency 20 kHz • In-Circuit Serial ProgrammingTM (ICSPTM) via two pins Special Microcontroller Features: • Precision Internal Oscillator: - Factory calibrated to ±1% - Software selectable frequency range of 8 MHz to 32 kHz - Software tunable - Two-Speed Start-up mode - Crystal fail detect for critical applications - Clock mode switching during operation for power savings • Power-saving Sleep mode • Wide operating voltage range (2.0V-5.5V) • Industrial and Extended temperature range • Power-on Reset (POR) • Power-up Timer (PWRT) and Oscillator Start-up Timer (OST) • Brown-out Reset (BOR) with software control option • Enhanced Low-Current Watchdog Timer (WDT) with on-chip oscillator (software selectable nominal 268 seconds with full prescaler) with software enable • Multiplexed Master Clear with pull-up/input pin • Programmable code protection • High-Endurance Flash/EEPROM cell: - 100,000 write Flash endurance - 1,000,000 write EEPROM endurance - Flash/Data EEPROM retention: > 40 years Low-Power Features: • Standby Current: - 30 nA @ 2.0V, typical • Operating Current: - 8.5 μA @ 32 kHz, 2.0V, typical - 100 μA @ 1 MHz, 2.0V, typical • Watchdog Timer Current: - 1 μA @ 2.0V, typical • Timer1 Oscillator Current: - 2 μA @ 32 kHz, 2.0V, typical © 2005 Microchip Technology Inc. Preliminary DS41249B-page 1 PIC16F785 Program Memory Data Memory Device I/O Flash SRAM EEPROM (words) (bytes) (bytes) PIC16F785 2048 128 256 17+1 10-bit A/D Operational Comparators CCP (ch) Amplifiers 12+2 2 2 TwoPhase PWM Timers 8/16-bit 1 2/1 1 Pin Diagram VDD RA5/T1CKI/OSC1/CLKIN RA4/AN3/T1G/OSC2/CLKOUT RA3/MCLR/VPP RC5/CCP1 RC4/C2OUT/PH2 RC3/AN7/C12IN3-/OP1 RC6/AN8/OP1RC7/AN9/OP1+ RB7/SYNC DS41249B-page 2 1 2 3 4 5 6 7 8 9 10 PIC16F785 20-pin PDIP, SOIC, SSOP 20 19 18 17 16 15 14 13 12 11 Preliminary VSS RA0/AN0/C1IN+/ICSPDAT RA1/AN1/C12IN0-/VREF/ICSPCLK RA2/AN2/T0CKI/INT/C1OUT RC0/AN4/C2IN+ RC1/AN5/C12IN1-/PH1 RC2/AN6/C12IN2-/OP2 RB4/AN10/OP2RB5/AN11/OP2+ RB6 © 2005 Microchip Technology Inc. PIC16F785 Table of Contents 1.0 Device Overview .......................................................................................................................................................................... 5 2.0 Memory Organization ................................................................................................................................................................... 9 3.0 Clock Sources ............................................................................................................................................................................ 23 4.0 I/O Ports ..................................................................................................................................................................................... 35 5.0 Timer0 Module ........................................................................................................................................................................... 49 6.0 Timer1 Module with Gate Control............................................................................................................................................... 51 7.0 Timer2 Module ........................................................................................................................................................................... 55 8.0 Capture/Compare/PWM (CCP) Module ..................................................................................................................................... 57 9.0 Comparator Module.................................................................................................................................................................... 63 10.0 Voltage References.................................................................................................................................................................... 71 11.0 Operational Amplifier (OPA) Module .......................................................................................................................................... 75 12.0 Analog-to-Digital Converter (A/D) Module.................................................................................................................................. 79 13.0 Two-Phase PWM ....................................................................................................................................................................... 91 14.0 Data EEPROM Memory ........................................................................................................................................................... 103 15.0 Special Features of the CPU.................................................................................................................................................... 107 16.0 Instruction Set Summary .......................................................................................................................................................... 127 17.0 Development Support............................................................................................................................................................... 137 18.0 Electrical Specifications............................................................................................................................................................ 143 19.0 AC and DC Characterization .................................................................................................................................................... 165 20.0 Packaging Information.............................................................................................................................................................. 167 Appendix A: Data Sheet Revision History.......................................................................................................................................... 171 Appendix B: Migrating from other PICmicro® DeviceS...................................................................................................................... 171 Index .................................................................................................................................................................................................. 173 On-Line Support................................................................................................................................................................................. 179 Systems Information and Upgrade Hot Line ...................................................................................................................................... 179 Reader Response .............................................................................................................................................................................. 180 Product Identification System ............................................................................................................................................................ 181 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 [email protected] 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. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 3 PIC16F785 NOTES: DS41249B-page 4 Preliminary © 2005 Microchip Technology Inc. PIC16F785 1.0 DEVICE OVERVIEW this Data Sheet and is highly recommended reading for a better understanding of the device architecture and operation of the peripheral modules. This document contains device specific information for the PIC16F785. Additional information may be found in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023), which may be obtained from your local Microchip Sales Representative or downloaded from the Microchip web site. The Reference Manual should be considered a complementary document to FIGURE 1-1: The PIC16F785 is covered by this Data Sheet. It is available in 20-pin PDIP, SOIC and SSOP packages. Figure 1-1 shows a block diagram of the PIC16F785 device. Table 1-1 shows the pinout description. PIC16F785 Block Diagram INT Configuration 13 8 Data Bus PORTA Program Counter Flash 2k X 14 Program Memory Program Bus RA0 RA1 RA2 RAM 128 bytes File Registers 8-Level Stack (13-bit) 14 RAM Addr RA3 RA4 RA5 PORTB 9 ADDR MUX Instruction reg 7 Direct Addr RB4 RB5 Indirect Addr 8 RB6 RB7 FSR Reg PORTC Status Reg RC0 8 RC1 RC2 3 MUX Power-up Timer 32 kHz Internal Oscillator Instruction Decode and Control Power-on Reset Timing Generation OSC2/CLKOUT RC4 Oscillator Start-up Timer OSC1/CLKIN RC3 RC5 ALU RC6 RC7 8 Watchdog Timer W Reg OP1 Brown-out Reset 8 Mhz Internal Oscillator OP1+ Dual Op Amps MCLR VDD VSS Timer1 Timer2 OP2EEDATA T1CKI Timer0 CCP T0CKI 256 bytes Data EEPROM EEADDR Two-Phase PWM AN0 AN1 AN2 AN3 AN4 AN5 AN6 AN7 AN3 AN8 AN9 AN10 AN11 © 2005 Microchip Technology Inc. Voltage Reference 2 Analog Comparators VREF C1IN- C1IN+ C1OUT C2IN- C2IN+ C2OUT Preliminary PH1 PH2 SYNC 8 Analog-to-Digital Converter OP2 OP2+ CCP1 T1G OP1- DS41249B-page 5 PIC16F785 TABLE 1-1: PIC16F785 PINOUT DESCRIPTION Name RA0/AN0/C1IN+/ICSPDAT RA1/AN1/C12IN0-/VREF/ICSPCLK RA2/AN2/T0CKI/INT/C1OUT RA3/MCLR/VPP RA4/AN3/T1G/OSC2/CLKOUT RA5/T1CKI/OSC1/CLKIN RB4/AN10/OP2- RB5/AN11/OP2+ Pin Function 19 18 17 4 3 2 13 12 Input Type Output Type Description RA0 TTL CMOS AN0 AN — A/D Channel 0 input PORTA I/O with prog. pull-up and interrupt-on-change Comparator 1 non-inverting input C1IN+ AN — ICSPDAT ST CMOS Serial Programming Data I/O RA1 TTL CMOS PORTA I/O with prog. pull-up and interrupt-on-change AN1 AN — A/D Channel 1 input C12IN0- AN — Comparator 1 and 2 inverting input VREF AN AN External Voltage Reference for A/D, buffered reference output Serial Programming Clock ICSPCLK ST — RA2 ST CMOS AN2 AN — T0CKI ST — Timer0 clock input INT ST — External Interrupt C1OUT — CMOS RA3 TTL — PORTA input with prog. pull-up and interrupt-on-change MCLR ST — Master Clear with internal pull-up Programming voltage PORTA I/O with prog. pull-up and interrupt-on-change A/D Channel 2 input Comparator 1 output VPP HV — RA4 TTL CMOS AN3 AN — T1G ST — OSC2 — XTAL Crystal/Resonator CLKOUT — CMOS FOSC/4 output RA5 TTL CMOS T1CKI ST — PORTA I/O with prog. pull-up and interrupt-on-change A/D Channel 3 input Timer1 gate PORTA I/O with prog. pull-up and interrupt-on-change Timer1 clock OSC1 XTAL — Crystal/Resonator CLKIN ST — External clock input/RC oscillator connection RB4 TTL CMOS AN10 AN — PORTB I/O A/D Channel 10 input OP2- — AN Op Amp 2 inverting input RB5 TTL CMOS AN11 AN — PORTB I/O A/D Channel 11 input OP2+ — AN Op Amp 2 non-inverting input RB6 11 RB6 TTL OD RB7/SYNC 10 RB7 TTL CMOS PORTB I/O SYNC ST CMOS Master PWM Sync output or slave PWM Sync input RC0/AN4/C2IN+ 16 RC0 TTL CMOS AN4 AN — A/D Channel 4 input Comparator 2 non-inverting input RC1/AN5/C12IN1-/PH1 RC2/AN6/C12IN2-/OP2 Legend: 15 14 PORTB I/O. Open drain output PORTC I/O C2IN+ AN — RC1 TTL CMOS AN5 AN — A/D Channel 5 input C12IN1- AN — Comparator 1 and 2 inverting input PH1 — CMOS RC2 TTL CMOS AN6 AN — A/D Channel 6 input C12IN2- AN — Comparator 1 and 2 inverting input OP2 — AN Op Amp 2 output PORTC I/O PWM phase 1 output PORTC I/O TTL = TTL input buffer, ST = Schmitt Trigger input buffer, AN = Analog, OD = Open Drain output, HV = High Voltage DS41249B-page 6 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 1-1: PIC16F785 PINOUT DESCRIPTION (CONTINUED) Name Input Type Output Type RC3 TTL CMOS AN7 AN — A/D Channel 7 input C12IN3- AN — Comparator 1 and 2 inverting input OP1 — AN Op Amp 1 output RC4 TTL CMOS PORTC I/O C2OUT — CMOS Comparator 2 output Pin Function RC3/AN7/C12IN3-/OP1 7 RC4/C2OUT/PH2 6 RC5/CCP1 5 RC6/AN8/OP1- 8 RC7/AN9/OP1+ 9 VDD Legend: PORTC I/O PH2 — CMOS PWM phase 2 output RC5 TTL CMOS PORTC I/O CCP1 ST CMOS Capture input/Compare output RC6 TTL CMOS AN8 AN — A/D Channel 8 input OP1- AN — Op Amp 1 inverting input RC7 AN9 VSS Description CMOS AN — PORTC I/O PORTC I/O A/D Channel 9 input OP1+ AN — Op Amp 1 non-inverting input 20 VSS Power — Ground reference 1 VDD Power — Positive supply TTL = TTL input buffer, ST = Schmitt Trigger input buffer, AN = Analog, OD = Open Drain output, HV = High Voltage TABLE 1-2: PIC16F785 PIN USAGE SUMMARY I/O Pin Analog Comp. Op Amps PWM Timers CCP RA0 19 RA1 RA2 Interrupt Pull-ups Basic AN0 C1IN+ — — — — IOC Y ICSPDAT 18 AN1/VREF C12IN0- — — — — IOC Y ICSPCLK 17 AN2 C1OUT — — T0CKI — INT/IOC Y — RA3(1) 4 — — — — — — IOC Y MCLR RA4 3 AN3 — — — T1G — IOC Y OSC2/CLKOUT RA5 2 — — — — T1CKI — IOC Y OSC1/CLKIN RB4 13 AN10 — OP2- — — — — — — RB5 12 AN11 — OP2+ — — — — — — RB6(2) 11 — — — — — — — — — RB7 10 — — — SYNC — — — — — RC0 16 AN4 C2IN+ — — — — — — — RC1 15 AN5 C12IN1- — PH1 — — — — — RC2 14 AN6 C12IN2- OP2 — — — — — — RC3 7 AN7 C12IN3- OP1 — — — — — — RC4 6 — C2OUT — PH2 — — — — — RC5 5 — — — — — CCP1 — — — RC6 8 AN8 — OP1- — — — — — — RC7 9 AN9 — OP1+ — — — — — — — 1 — — — — — — — — VDD — 20 — — — — — — — — VSS Note 1: 2: Input only. Open drain. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 7 PIC16F785 NOTES: DS41249B-page 8 Preliminary © 2005 Microchip Technology Inc. PIC16F785 2.0 MEMORY ORGANIZATION 2.1 Program Memory Organization 2.2 The PIC16F785 has a 13-bit program counter capable of addressing an 8k x 14 program memory space. Only the first 2k x 14 (0000h-07FFh) for the PIC16F785 is physically implemented. Accessing a location above these boundaries will cause a wrap around within the first 2k x 14 space. The Reset vector is at 0000h and the interrupt vector is at 0004h (see Figure 2-1). FIGURE 2-1: PROGRAM MEMORY MAP AND STACK FOR THE PIC16F785 PC<12:0> CALL, RETURN RETFIE, RETLW 13 Stack Level 1 Stack Level 2 Stack Level 8 Reset Vector Interrupt Vector Data Memory Organization The data memory (see Figure 2-2) is partitioned into four banks, which contain the General Purpose Registers (GPR) and the Special Function Registers (SFR). The Special Function Registers are located in the first 32 locations of each bank. Register locations 20h-7Fh in Bank 0 and A0h-BFh in Bank 1 are General Purpose Registers, implemented as static RAM. The last sixteen register locations in Bank 1 (F0h-FFh), Bank 2 (170h-17Fh), and Bank 3 (1F0h-1FFh) point to addresses 70h-7Fh in Bank 0. All other RAM is unimplemented and returns ‘0’ when read. Seven address bits are required to access any location in a data memory bank. Two additional bits are required to access the four banks. When data memory is accessed directly, the seven Least Significant address bits are contained within the opcode and the two Most Significant bits are contained in the STATUS register. RP0 and RP1 (STATUS<5> and STATUS<6>) are the two Most Significant data memory address bits and are also known as the bank select bits. Table 2-1 lists how to access the four banks of registers. TABLE 2-1: BANK SELECTION RP1 RP0 Bank0 0 0 Bank1 0 1 0004 Bank2 1 0 0005 Bank3 1 1 000H On-chip Program 2.2.1 Memory 07FFH 0800H 1FFFH GENERAL PURPOSE REGISTER FILE The register file banks are organized as 128 x 8 in the PIC16F785. Each register is accessed, either directly, by seven address bits within the opcode, or indirectly, through the File Select Register (FSR). When the FSR is used to access data memory, the eight Least Significant data memory address bits are contained in the FSR and the ninth Most Significant address bit is contained in the IRP bit (STATUS<7>) of the STATUS register. (see Section 2.4 “Indirect Addressing, INDF and FSR Registers”). 2.2.2 SPECIAL FUNCTION REGISTERS The Special Function Registers are registers used by the CPU and peripheral functions for controlling the desired operation of the device (see Table 2-2). These registers are static RAM. The special registers can be classified into two sets: core and peripheral. The Special Function Registers associated with the “core” are described in this section. Those related to the operation of the peripheral features are described in the section of that peripheral feature. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 9 PIC16F785 FIGURE 2-2: DATA MEMORY MAP OF THE PIC16F785 File Address Indirect addr.(1) TMR0 PCL STATUS FSR PORTA PORTB PORTC PCLATH INTCON PIR1 TMR1L TMR1H T1CON TMR2 T2CON CCPR1L CCPR1H CCP1CON WDTCON ADRESH ADCON0 File Address 00h 01h 02h 03h 04h 05h 06h 07h 08h 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 19h 1Ah 1Bh 1Ch Indirect addr.(1) OPTION_REG PCL STATUS FSR TRISA TRISB TRISC 1Dh 1Eh 1Fh 20h General Purpose Register 96 Bytes 6Fh 70h 7Fh Bank 0 File Address 80h 81h 82h 83h 84h 85h 86h 87h 88h 89h 8Ah 8Bh 8Ch 8Dh 8Eh 8Fh 90h 91h 92h 93h 94h 95h 96h 97h 98h 99h 9Ah 9Bh 9Ch Indirect addr.(1) TMR0 PCL STATUS FSR PORTA PORTB PORTC EECON2(1) ADRESL ADCON1 General Purpose Register 9Dh 9Eh 9Fh A0h OPA2CON 32 Bytes BFh C0h PCLATH INTCON PIE1 PCON OSCCON OSCTUNE ANSEL0 PR2 ANSEL1 WPUA IOCA REFCON VRCON EEDAT EEADR EECON1 accesses Bank 0 PCLATH INTCON PWMCON1 PWMCON0 PWMCLK PWMPH1 PWMPH2 CM1CON0 CM2CON0 CM2CON1 OPA1CON EFh F0h FFh Bank1 accesses Bank 0 Bank2 100h 101h 102h 103h 104h 105h 106h 107h 108h 109h 10Ah 10Bh 10Ch 10Dh 10Eh 10Fh 110h 111h 112h 113h 114h 115h 116h 117h 118h 119h 11Ah 11Bh 11Ch File Address Indirect addr.(1) OPTION_REG PCL STATUS FSR TRISA TRISB TRISC PCLATH INTCON 180h 181h 182h 183h 184h 185h 186h 187h 188h 189h 18Ah 18Bh 18Ch 18Dh 18Eh 18Fh 190h 191h 192h 193h 194h 195h 196h 197h 198h 199h 19Ah 19Bh 19Ch 11Dh 11Eh 11Fh 120h 19Dh 19Eh 19Fh 1A0h 16Fh 170h 17Fh 1EFh 1F0h 1FFh accesses Bank 0 Bank3 Unimplemented data memory locations, read as ‘0’. Note 1: Not a physical register. DS41249B-page 10 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 2-2: Addr Name PIC16F785 SPECIAL FUNCTION REGISTERS SUMMARY BANK 0 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Page Bank 0 00h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx 22,114 01h TMR0 Timer0 Module’s Register xxxx xxxx 49,114 02h PCL Program Counter's (PC) Least Significant Byte 0000 0000 21,114 03h STATUS 0001 1xxx 15,114 IRP RP1 RP0 TO PD Z DC C 04h FSR xxxx xxxx 22,114 05h PORTA(1) Indirect Data Memory Address Pointer — — RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 35,114 06h PORTB(1) RB7 RB6 RB5 RB4 — — — — xx00 ---- 42,114 07h PORTC(1) RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 00xx 0000 45,114 — 08h — Unimplemented — 09h — Unimplemented — — ---0 0000 21,114 0Ah PCLATH 0Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 17,114 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 19,114 — — 0Dh — 0Eh TMR1L 0Fh TMR1H 10h T1CON 11h TMR2 12h T2CON 13h CCPR1L 14h CCPR1H 15h CCP1CON 16h — Unimplemented 17h — Unimplemented 18h WDTCON — Write Buffer for Upper 5 bits of Program Counter Unimplemented — — Holding Register for the Least Significant Byte of the 16-bit TMR1 xxxx xxxx 51,114 Holding Register for the Most Significant Byte of the 16-bit TMR1 xxxx xxxx 51,114 53,114 T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 0000 0000 55,114 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 55,114 Capture/Compare/PWM Register1 Low Byte xxxx xxxx 57,114 Capture/Compare/PWM Register1 High Byte xxxx xxxx 57,114 --00 0000 57,114 — — — — Timer2 Module Register — TOUTPS3 — — — — DC1B1 — DC1B0 WDTPS3 CCP1M3 WDTPS2 CCP1M2 WDTPS1 CCP1M1 WDTPS0 CCP1M0 SWDTEN ---0 1000 122,114 19h — Unimplemented — — 1Ah — Unimplemented — — 1Bh — Unimplemented — — 1Ch — Unimplemented — — 1Dh — Unimplemented — — xxxx xxxx 81,114 0000 0000 83,114 1Eh ADRESH 1Fh ADCON0 Legend: Note 1: Most Significant 8 bits of the left justified A/D result or 2 bits of right justified result ADFM VCFG CHS3 CHS2 CHS1 CHS0 GO/DONE ADON – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Port pins with analog functions controlled by the ANSEL0 and ANSEL1 registers will read ‘0’ immediately after a Reset even though the data latches are either undefined (POR) or unchanged (other Resets). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 11 PIC16F785 TABLE 2-3: Addr PIC16F785 SPECIAL FUNCTION REGISTERS SUMMARY BANK 1 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Page xxxx xxxx 22,114 1111 1111 16,114 0000 0000 21,114 0001 1xxx 15,114 Bank 1 80h INDF 81h OPTION_REG Addressing this location uses contents of FSR to address data memory (not a physical register) 82h PCL 83h STATUS 84h FSR 85h TRISA 86h TRISB TRISB7 TRISB6 TRISB5 TRISB4 — — 87h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Program Counter's (PC) Least Significant Byte IRP RP1 RP0 TO PD Z DC C Indirect Data Memory Address Pointer — — TRISA5 TRISA4 TRISA3 TRISA2 xxxx xxxx 22,114 TRISA0 --11 1111 36,114 — — 1111 ---- 42,114 TRISC1 TRISC0 1111 1111 45,114 — TRISA1 88h — Unimplemented — 89h — Unimplemented — — 8Ah PCLATH ---0 0000 21,114 8Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 17,114 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 18,114 8Dh 8Eh — — — — Write Buffer for Upper 5 bits of Program Counter Unimplemented — — ---1 --qq 20,114 PCON — — — SBOREN — 8Fh OSCCON — IRCF2 IRCF1 IRCF0 OSTS(1) HTS LTS SCS -110 q000 33,114 90h OSCTUNE — — — TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 28,114 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 82,114 1111 1111 55,114 ---- 1111 82,115 91h ANSEL0 92h PR2 93h ANSEL1 94h — WPUA 96h IOCA 98h POR BOR Timer2 Module Period Register 95h 97h — — REFCON — — — — ANS11 ANS10 ANS9 ANS8 Unimplemented — — — — WPUA5 WPUA4 WPUA3(2) WPUA2 WPUA1 WPUA0 --11 1111 36,115 — — IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0 --00 0000 37,115 Unimplemented — — BGST VRBB VREN VROE CVROE — — — --00 000- 73,115 99h VRCON C1VREN C2VREN VRR — VR3 VR2 VR1 VR0 000- 0000 72,115 9Ah EEDAT EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0 0000 0000 103,115 EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0 0000 0000 103,115 — — — — WRERR WREN WR RD ---- x000 104,115 ---- ---- 104,115 9Bh EEADR 9Ch EECON1 9Dh EECON2 EEPROM Control Register 2 (not a physical register) 9Eh ADRESL Least Significant 2 bits of the left justified A/D result or 8 bits of the right justified result 9Fh ADCON1 Legend: Note 1: 2: — ADCS2 ADCS1 ADCS0 — — — — xxxx xxxx 80,115 -000 ---- 84,115 – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe mode is enabled, otherwise this bit resets to ‘1’. RA3 pull-up is enabled when MCLRE is ‘1’ in Configuration Word. DS41249B-page 12 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 2-4: Addr Name PIC16F785 SPECIAL FUNCTION REGISTERS SUMMARY BANK 2 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Page Bank 2 100h INDF Addressing this location uses contents of FSR to address data memory (not a physical register) xxxx xxxx 22,114 101h TMR0 Timer0 Module’s Register xxxx xxxx 49,114 102h PCL Program Counter's (PC) Least Significant Byte 0000 0000 21,114 103h STATUS 0001 1xxx 15,114 IRP RP1 RP0 TO PD Z DC C 104h FSR xxxx xxxx 22,114 105h PORTA(1) Indirect Data Memory Address Pointer — — RA5 RA4 RA3 RA2 RA1 RA0 --x0 x000 35,114 106h PORTB(1) RB7 RB6 RB5 RB4 — — — — xx00 ---- 42,114 107h PORTC(1) RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 00xx 0000 45,114 — 108h — Unimplemented — 109h — Unimplemented — — ---0 0000 21,114 10Ah PCLATH 10Bh INTCON — — — GIE PEIE T0IE Write Buffer for Upper 5 bits of Program Counter 0000 0000 17,114 10Ch — Unimplemented — — 10Dh — Unimplemented — — 10Eh — Unimplemented — — 10Fh — Unimplemented — — 110h PWMCON1 111h PWMCON0 112h PWMCLK 113h PWMPH1 114h PWMPH2 — INTE RAIE T0IF INTF RAIF COMOD1 COMOD0 CMDLY4 CMDLY3 CMDLY2 CMDLY1 CMDLY0 -000 0000 100,115 PRSEN PASEN BLANK2 BLANK1 SYNC1 SYNC0 PH2EN PH1EN 0000 0000 93,115 PWMASE PWMP1 PWMP0 PER4 PER3 PER2 PER1 PER0 0000 0000 94,115 POL C2EN C1EN PH4 PH3 PH2 PH1 PH0 0000 0000 95,115 POL C2EN C1EN PH4 PH3 PH2 PH1 PH0 0000 0000 96,115 115h — Unimplemented — — 116h — Unimplemented — — 117h — Unimplemented — — 118h — Unimplemented — — 119h CM1CON0 C1CH0 0000 0000 65,115 11Ah CM2CON0 11Bh CM2CON1 11Ch OPA1CON 11Dh OPA2CON 11Eh — 11Fh — Legend: Note 1: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented Port pins with analog functions controlled by the ANSEL0 and ANSEL1 registers will read ‘0’ immediately after a Reset even though the data latches are either undefined (POR) or unchanged (other Resets). C1ON C1OUT C1OE C1POL C1SP C1R C2ON C2OUT C2OE C2POL C2SP C2R C2CH1 C2CH0 0000 0000 67,115 MC1OUT MC2OUT — — — — T1GSS C2SYNC 00-- --10 68,115 OPAON — — — — — — — 0--- ---- 76,115 OPAON — — — — — — — 0--- ---- 76,115 Unimplemented — — Unimplemented — — © 2005 Microchip Technology Inc. Preliminary C1CH1 DS41249B-page 13 PIC16F785 TABLE 2-5: Addr PIC16F785 SPECIAL FUNCTION REGISTERS SUMMARY BANK 3 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Page xxxx xxxx 22,114 1111 1111 16,114 0000 0000 21,114 0001 1xxx 15,114 Bank 3 180h INDF 181h OPTION_REG Addressing this location uses contents of FSR to address data memory (not a physical register) 182h PCL 183h STATUS 184h FSR 185h TRISA 186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 — — 187h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 Program Counter's (PC) Least Significant Byte IRP RP1 RP0 TO PD Z DC C Indirect Data Memory Address Pointer — — TRISA5 TRISA4 TRISA3 TRISA2 xxxx xxxx 22,114 TRISA0 --11 1111 36,114 — — 1111 ---- 42,114 TRISC1 TRISC0 1111 1111 45,114 — TRISA1 188h — Unimplemented — 189h — Unimplemented — — 18Ah PCLATH ---0 0000 21,114 18Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 17,114 18Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 18,114 — — — Write Buffer for Upper 5 bits of Program Counter 18Dh — Unimplemented — — 18Eh — Unimplemented — — 18Fh — Unimplemented — — 190h — Unimplemented — — 191h — Unimplemented — — 192h — Unimplemented — — 193h — Unimplemented — — 194h — Unimplemented — — 195h — Unimplemented — — 196h — Unimplemented — — 197h — Unimplemented — — 198h — Unimplemented — — 199h — Unimplemented — — 19Ah — Unimplemented — — 19Bh — Unimplemented — — 19Ch — Unimplemented — — 19Dh — Unimplemented — — 19Eh — Unimplemented — — 19Fh — Unimplemented — — Legend: – = Unimplemented locations read as ‘0’, u = unchanged, x = unknown, q = value depends on condition, shaded = unimplemented DS41249B-page 14 Preliminary © 2005 Microchip Technology Inc. PIC16F785 2.2.2.1 STATUS Register The STATUS register, shown in Register 2-1, contains: • the arithmetic status of the ALU • the Reset status • the bank select bits for data memory (SRAM) The STATUS register can be the destination for any instruction, like any other register. If the STATUS register is the destination for an instruction that affects the Z, DC or C bits, then the write to these three bits is disabled. These bits are set or cleared according to the device logic. Furthermore, the TO and PD bits are not writable. Therefore, the result of an instruction with the STATUS register as destination may be different than intended. REGISTER 2-1: For example, CLRF STATUS will clear the upper three bits and set the Z bit. This leaves the STATUS register as 000u u1uu (where u = unchanged). It is recommended, therefore, that only BCF, BSF, SWAPF and MOVWF instructions are used to alter the STATUS register, because these instructions do not affect any Status bits. For other instructions not affecting any Status bits, see Section 16.0 “Instruction Set Summary”. Note: The C and DC bits operate as a Borrow and Digit Borrow out bit, respectively, in subtraction. See the SUBLW and SUBWF instructions for examples. STATUS – STATUS REGISTER (ADDRESS: 03h, 83h, 103h OR 183h) R/W-0 R/W-0 R/W-0 R-1 R-1 R/W-x R/W-x R/W-x IRP RP1 RP0 TO PD Z DC(1) C(1) bit 7 bit 0 bit 7 IRP: Register Bank Select bit (used for indirect addressing) 1 = Bank 2,3 (100h-1FFh) 0 = Bank 0,1 (00h-FFh) bit 6-5 RP<1:0>: Register Bank Select bits (used for direct addressing) 11 = Bank 3 (180h-1FFh) 10 = Bank 2 (100h-17Fh) 01 = Bank 1 (80h-FFh) 00 = Bank 0 (00h-7Fh) bit 4 TO: Time-out bit 1 = After power-up, CLRWDT instruction, or SLEEP instruction 0 = A WDT time-out occurred bit 3 PD: Power-down bit 1 = After power-up or by the CLRWDT instruction 0 = By execution of the SLEEP instruction bit 2 Z: Zero bit 1 = The result of an arithmetic or logic operation is zero 0 = The result of an arithmetic or logic operation is not zero bit 1 DC: Digit Carry/Borrow bit (ADDWF, ADDLW,SUBLW,SUBWF instructions)(1) For borrow, the polarity is reversed. 1 = A carry-out from the 4th low-order bit of the result occurred 0 = No carry-out from the 4th low-order bit of the result bit 0 C: Carry/Borrow bit (ADDWF, ADDLW, SUBLW, SUBWF instructions)(1) 1 = A carry-out from the Most Significant bit of the result occurred 0 = No carry-out from the Most Significant bit of the result occurred Note 1: For Borrow, the polarity is reversed. A subtraction is executed by adding the two’s complement of the second operand. For rotate (RRF, RLF) instructions, this bit is loaded with either the high-order or low-order bit of the source register. Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 15 PIC16F785 2.2.2.2 Option Register Note: The Option (OPTION_REG) register, shown in Register 2-2, is a readable and writable register, which contains various control bits to configure: • • • • To achieve a 1:1 prescaler assignment for TMR0, assign the prescaler to the WDT by setting PSA bit to ‘1’ (OPTION_REG<3>). See Section 5.4 “Prescaler”. TMR0/WDT prescaler External RA2/INT interrupt TMR0 Weak pull-ups on PORTA REGISTER 2-2: OPTION_REG – OPTION REGISTER (ADDRESS: 81h OR 181h) R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 bit 7 bit 0 bit 7 RAPU: PORTA Pull-up Enable bit 1 = PORTA pull-ups are disabled 0 = PORTA pull-ups are enabled by individual port latch values in WPUA register bit 6 INTEDG: Interrupt Edge Select bit 1 = Interrupt on rising edge of RA2/AN2/T0CKI/INT/C1OUT pin 0 = Interrupt on falling edge of RA2/AN2/T0CKI/INT/C1OUT pin bit 5 T0CS: TMR0 Clock Source Select bit 1 = Transition on RA2/AN2/T0CKI/INT/C1OUT pin 0 = Internal instruction cycle clock (CLKOUT) bit 4 T0SE: TMR0 Source Edge Select bit 1 = Increment on high-to-low transition on RA2/AN2/T0CKI/INT/C1OUT pin 0 = Increment on low-to-high transition on RA2/AN2/T0CKI/INT/C1OUT pin bit 3 PSA: Prescaler Assignment bit 1 = Prescaler is assigned to the WDT 0 = Prescaler is assigned to the Timer0 module bit 2-0 PS<2:0>: Prescaler Rate Select bits Bit Value 000 001 010 011 100 101 110 111 TMR0 Rate WDT Rate(1) 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 1 : 256 1:1 1:2 1:4 1:8 1 : 16 1 : 32 1 : 64 1 : 128 Note 1: A dedicated 16-bit WDT postscaler is available for the PIC16F785. See Section 15.5 “Watchdog Timer (WDT)” for more information. Legend: DS41249B-page 16 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 2.2.2.3 INTCON Register Note: The Interrupt Control (INTCON) register, shown in Register 2-3, is a readable and writable register, which contains the various enable and flag bits for TMR0 register overflow, PORTA change and external RA2/INT pin interrupts. REGISTER 2-3: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit, GIE (INTCON<7>). User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. INTCON – INTERRUPT CONTROL REGISTER (ADDRESS: 0Bh, 8Bh, 103h OR 183h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 GIE PEIE T0IE INTE RAIE(1) T0IF(2) INTF RAIF bit 7 bit 0 bit 7 GIE: Global Interrupt Enable bit 1 = Enables all unmasked interrupts 0 = Disables all interrupts bit 6 PEIE: Peripheral Interrupt Enable bit 1 = Enables all unmasked peripheral interrupts 0 = Disables all peripheral interrupts bit 5 T0IE: TMR0 Overflow Interrupt Enable bit 1 = Enables the TMR0 interrupt 0 = Disables the TMR0 interrupt bit 4 INTE: RA2/AN2/T0CKI/INT/C1OUT External Interrupt Enable bit 1 = Enables the RA2/AN2/T0CKI/INT/C1OUT external interrupt 0 = Disables the RA2/AN2/T0CKI/INT/C1OUT external interrupt bit 3 RAIE: PORTA Change Interrupt Enable bit(1) 1 = Enables the PORTA change interrupt 0 = Disables the PORTA change interrupt bit 2 T0IF: TMR0 Overflow Interrupt Flag bit(2) 1 = TMR0 register has overflowed (must be cleared in software) 0 = TMR0 register did not overflow bit 1 INTF: RA2/AN2/T0CKI/INT/C1OUT External Interrupt Flag bit 1 = The RA2/AN2/T0CKI/INT/C1OUT external interrupt occurred (must be cleared in software) 0 = The RA2/AN2/T0CKI/INT/C1OUT external interrupt did not occur bit 0 RAIF: PORTA Change Interrupt Flag bit 1 = When at least one of the PORTA <5:0> pins changed state (must be cleared in software) 0 = None of the PORTA <5:0> pins have changed state Note 1: IOCA register must also be enabled. 2: T0IF bit is set when Timer0 rolls over. Timer0 is unchanged on Reset and should be initialized before clearing T0IF bit. Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 17 PIC16F785 2.2.2.4 PIE1 Register The Peripheral Interrupt Enable (PIE1) Register 1, shown in Register 2-4, contains the interrupt enable bits, as shown in Register 2-4. REGISTER 2-4: Note: Bit PEIE (INTCON<6>) must be set to enable any peripheral interrupt. PIE1 – PERIPHERAL INTERRUPT ENABLE REGISTER 1 (ADDRESS: 8Ch) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE bit 7 bit 0 bit 7 EEIE: EE Write Complete Interrupt Enable bit 1 = Enables the EE write complete interrupt 0 = Disables the EE write complete interrupt bit 6 ADIE: A/D Converter Interrupt Enable bit 1 = Enables the A/D converter interrupt 0 = Disables the A/D converter interrupt bit 5 CCP1IE: CCP1 Interrupt Enable bit 1 = Enables the CCP1 interrupt 0 = Disables the CCP1 interrupt bit 4 C2IE: Comparator 2 Interrupt Enable bit 1 = Enables the Comparator 2 interrupt 0 = Disables the Comparator 2 interrupt bit 3 C1IE: Comparator 1 Interrupt Enable bit 1 = Enables the Comparator 1 interrupt 0 = Disables the Comparator 1 interrupt bit 2 OSFIE: Oscillator Fail Interrupt Enable bit 1 = Enables the Oscillator Fail interrupt 0 = Disables the Oscillator Fail interrupt bit 1 TMR2IE: Timer2 to PR2 Match Interrupt Enable bit 1 = Enables the Timer2 to PR2 match interrupt 0 = Disables the Timer2 to PR2 match interrupt bit 0 TMR1IE: Timer1 Overflow Interrupt Enable bit 1 = Enables the Timer1 overflow interrupt 0 = Disables the Timer1 overflow interrupt Legend: DS41249B-page 18 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 2.2.2.5 PIR1 Register The Peripheral Interrupt (PIR1) Register 1 contains the interrupt flag bits, as shown in Register 2-5. REGISTER 2-5: Note: Interrupt flag bits are set when an interrupt condition occurs, regardless of the state of its corresponding enable bit or the global enable bit, GIE (INTCON<7>). User software should ensure the appropriate interrupt flag bits are clear prior to enabling an interrupt. PIR1 – PERIPHERAL INTERRUPT REGISTER 1 (ADDRESS: 0Ch) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF bit 7 bit 0 bit 7 EEIF: EEPROM Write Operation Interrupt Flag bit 1 = The write operation completed (must be cleared in software) 0 = The write operation has not completed or has not been started bit 6 ADIF: A/D Interrupt Flag bit 1 = A/D conversion complete 0 = A/D conversion has not completed or has not been started bit 5 CCP1IF: CCP1 Interrupt Flag bit Capture mode: 1 = A TMR1 register capture occurred (must be cleared in software) 0 = No TMR1 register 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 4 C2IF: Comparator 2 Interrupt Flag bit 1 = Comparator 2 output has changed (must be cleared in software) 0 = Comparator 2 output has not changed bit 3 C1IF: Comparator 1 Interrupt Flag bit 1 = Comparator 1 output has changed (must be cleared in software) 0 = Comparator 1 output has not changed bit 2 OSFIF: Oscillator Fail Interrupt Flag bit 1 = System oscillator failed, clock input has changed to INTOSC (must be cleared in software) 0 = System clock operating bit 1 TMR2IF: Timer2 to PR2 Match Interrupt Flag bit 1 = Timer2 to PR2 match occurred (must be cleared in software) 0 = Timer2 to PR2 match has not occurred bit 0 TMR1IF: Timer1 Overflow Interrupt Flag bit 1 = Timer1 register overflowed (must be cleared in software) 0 = Timer1 has not overflowed 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 19 PIC16F785 2.2.2.6 PCON Register The Power Control (PCON) register (see Table 15-2) contains flag bits to differentiate between a: • • • • Power-on Reset (POR) Brown-out Reset (BOR) Watchdog Timer Reset (WDT) External MCLR Reset The PCON register bits are shown in Register 2-6. REGISTER 2-6: PCON – POWER CONTROL REGISTER (ADDRESS: 8Eh) U-0 U-0 U-0 R/W-1 U-0 U-0 R/W-0 R/W-x — — — SBOREN(1) — — POR BOR bit 7 bit 0 bit 7-5 Unimplemented: Read as ‘0’ bit 4 SBOREN: Software BOR Enable bit(1) 1 = BOR enabled 0 = BOR disabled bit 3-2 Unimplemented: Read as ‘0’ bit 1 POR: Power-on Reset Status bit 1 = No Power-on Reset occurred 0 = A Power-on Reset occurred (must be set in software after a Power-on Reset occurs) bit 0 BOR: Brown-out Reset Status bit 1 = No Brown-out Reset occurred 0 = A Brown-out Reset occurred (must be set in software after a Brown-out Reset occurs) Note 1: BOREN<1:0> = 01 in Configuration Word for this bit to control the BOR. Legend: DS41249B-page 20 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 2.3 FIGURE 2-3: PCL and PCLATH The Program Counter (PC) specifies the address of the instruction to fetch for execution. The program counter is 13 bits wide. The low byte is called the PCL register. The PCL register is readable and writable. The high byte of the PC (PC<12:8>) is called the PCH register. This register contains PC<12:8> bits which are not directly readable or writable. All updates to the PCH register go through the PCLATH register. On any Reset, the PC is cleared. Figure 2-3 shows the two situations for the loading of the PC. The upper example in Figure 2-3 shows how the PC is loaded on a write to PCL (PCLATH<4:0> → PCH). The lower example in Figure 2-3 shows how the PC is loaded during a CALL or GOTO instruction (PCLATH<4:3> → PCH). LOADING OF PC IN DIFFERENT SITUATIONS PCH PCL 12 8 7 0 PC 8 PCLATH<4:0> 5 Instruction with PCL as Destination ALU result PCLATH PCH 12 11 10 PCL 8 0 7 PC GOTO, CALL 2 PCLATH<4:3> 11 Opcode <10:0> PCLATH 2.3.1 MODIFYING PCL Executing any instruction with the PCL register as the destination simultaneously causes the Program Counter PC<12:8> bits (PCH) to be replaced by the contents of the PCLATH register. This allows the entire contents of the program counter to be changed by first writing the desired upper 5 bits to the PCLATH register. When the lower 8 bits are then written to the PCL register, all 13 bits of the program counter will change to the values contained in the PCLATH register and those being written to the PCL register. A computed GOTO is accomplished by adding an offset to the program counter (ADDWF PCL). Care should be exercised when jumping into a look-up table or program branch table (computed GOTO) by modifying the PCL register. Assuming that PCLATH is set to the table start address, if the table length is greater than 255 instructions, or if the lower 8 bits of the memory address rolls over from 0xFF to 0x00 in the middle of the table, then PCLATH must be incremented for each address rollover that occurs between the table beginning and the target location within the table. 2.3.3 The PIC16F785 family has an 8-level x 13-bit wide hardware stack (see Figure 2-1). The stack space is not part of either program or data space and the Stack Pointer is not readable or writable. The PC is PUSHed onto the stack when a CALL instruction is executed or an interrupt causes a branch. The stack is POPed in the event of a RETURN, RETLW or a RETFIE instruction execution. PCLATH is not affected by a PUSH or POP operation. The stack operates as a circular buffer. This means that after the stack has been PUSHed eight times, the ninth PUSH overwrites the value that was stored from the first PUSH. The tenth PUSH overwrites the second PUSH (and so on). Note 1: There are no Status bits to indicate stack overflow or stack underflow conditions. For more information refer to Application Note AN556, “Implementing a Table Read” (DS00556). 2.3.2 STACK 2: There are no instructions/mnemonics called PUSH or POP. These are actions that occur from the execution of the CALL, RETURN, RETLW and RETFIE instructions or the vectoring to an interrupt address. PROGRAM MEMORY PAGING The CALL and GOTO instructions provide 11 bits of address to allow branching within any 2K program memory page. When doing a CALL or GOTO instruction, the upper bit of the address is provided by PCLATH<3> (page select bit). When doing a CALL or GOTO instruction the user must ensure that the page select bit is programmed so that the desired destination program memory page is addressed. When the CALL instruction (or interrupt) is executed, the entire 13-bit PC return address is PUSHed onto the stack. Therefore, manipulation of the PCLATH<3> bit is not required for the RETURN or RETFIE instructions which POP the address from the stack. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 21 PIC16F785 2.4 Indirect Addressing, INDF and FSR Registers A simple program to clear RAM location 20h-2Fh using indirect addressing is shown in Example 2-1. The INDF register is not a physical register. Addressing the INDF register will cause indirect addressing. EXAMPLE 2-1: MOVLW MOVWF NEXT CLRF INCF BTFSS GOTO CONTINUE Indirect addressing is possible by using the INDF register. Any instruction using the INDF register actually accesses data pointed to by the File Select Register (FSR). Reading INDF itself indirectly will produce 00h. Writing to the INDF register indirectly results in a no operation (although Status bits may be affected). An effective 9-bit address is obtained by concatenating the 8-bit FSR and the IRP bit (STATUS<7>), as shown in Figure 2-4. FIGURE 2-4: INDIRECT ADDRESSING 0x20 FSR INDF FSR FSR,4 NEXT DIRECT/INDIRECT ADDRESSING PIC16F785 Direct Addressing RP1RP0 ;initialize pointer ;to RAM ;clear INDF register ;increment pointer ;all done? ;no clear next ;yes continue Indirect Addressing From Opcode 6 Bank Select 0 IRP 7 Bank Select Location Select 00 01 10 File Select Register 0 Location Select 11 00H 180H Data Memory 7FH 1FFH Bank 0 Note: Bank 1 Bank 2 Bank 3 For memory map detail see Figure 2-2. DS41249B-page 22 Preliminary © 2005 Microchip Technology Inc. PIC16F785 3.0 CLOCK SOURCES The PIC16F785 can be configured in one of eight clock modes. 3.1 Overview 1. 2. The PIC16F785 has a wide variety of clock sources and selection features to allow it to be used in a wide range of applications while maximizing performance and minimizing power consumption. Figure 3-1 illustrates a block diagram of the PIC16F785 clock sources. 3. 4. 5. Clock sources can be configured from external oscillators, quartz crystal resonators, ceramic resonators and Resistor-Capacitor (RC) circuits. In addition, the system clock source can be configured from one of two internal oscillators, with a choice of speeds selectable via software. Additional clock features include: 6. 7. 8. • Selectable system clock source between external or internal via software. • Two-speed Clock Start-up mode, which minimizes latency between external oscillator start-up and code execution. • Fail-Safe Clock Monitor (FSCM) designed to detect a failure of the external clock source (LP, XT, HS, EC or RC modes) and switch to the internal oscillator. FIGURE 3-1: EC – External clock with I/O on RA4. LP – 32.768 kHz Watch Crystal or Ceramic Resonator Oscillator mode. XT – Medium Gain Crystal or Ceramic Resonator Oscillator mode. HS – High Gain Crystal or Ceramic Resonator mode. RC – External Resistor-Capacitor (RC) with FOSC/4 output on RA4 RCIO – External Resistor-Capacitor with I/O on RA4. INTOSC – Internal Oscillator with FOSC/4 output on RA4 and I/O on RA5. INTOSCIO – Internal Oscillator with I/O on RA4 and RA5. Clock Source modes are configured by the FOSC<2:0> bits in the Configuration Word (see Section 15.0 “Special Features of the CPU”). Once the PIC16F785 is programmed and the Clock Source mode configured, it cannot be changed in software. PIC16F785 CLOCK SOURCE BLOCK DIAGRAM FOSC<2:0> (Configuration Word) SCS (OSCCON<0>) External Oscillator OSC2 Sleep IRCF<2:0> (OSCCON<6:4>) 8 MHz Internal Oscillator 4 MHz MUX LP, XT, HS, RC, RCIO, EC OSC1 System Clock (CPU and Peripherals) 111 110 101 1 MHz 100 500 kHz 250 kHz 125 kHz LFINTOSC 31 kHz 31 kHz 011 MUX HFINTOSC 8 MHz Postscaler 2 MHz 010 001 000 Power-up Timer (PWRT) Watchdog Timer (WDT) Fail-Safe Clock Monitor (FSCM) © 2005 Microchip Technology Inc. Preliminary DS41249B-page 23 PIC16F785 3.2 Clock Source Modes Clock Source modes can be classified as external or internal. 3.3 External Clock Modes 3.3.1 OSCILLATOR START-UP TIMER (OST) When the PIC16F785 is configured for any of the Crystal Oscillator modes (LP, XT or HS), the Oscillator Start-up Timer (OST) is enabled, which extends the reset period to allow the oscillator additional time to stabilize. The OST counts 1024 clock periods present on the OSC1 pin following a Power-on Reset (POR), a wake from Sleep, or when the Power-up Timer (PWRT) has expired (if the PWRT is enabled). During this time, the program counter does not increment and program execution is suspended. The OST ensures that the oscillator circuit, using a quartz crystal resonator or ceramic resonator, has started and is providing a stable system clock to the PIC16F785. Table 3-1 shows examples where the oscillator delay is invoked. • External Clock modes rely on external circuitry for the clock source. Examples are oscillator modules (EC mode), quartz crystal resonators or ceramic resonators (LP, XT, and HS modes), and resistorcapacitor (RC mode) circuits. • Internal clock sources are contained internally within the PIC16F785. The PIC16F785 has two internal oscillators; the 8 MHz High-frequency Internal Oscillator (HFINTOSC) and 31 kHz Lowfrequency Internal Oscillator (LFINTOSC). The system clock can be selected between external or internal clock sources via the System Clock Selection (SCS) bit (see Section 3.5 “Clock Switching”). In order to minimize latency between external oscillator start-up and code execution, the Two-speed Clock Start-up mode can be selected (see Section 3.6 “TwoSpeed Clock Start-up Mode”). TABLE 3-1: OSCILLATOR DELAY EXAMPLES Switch From Switch To Frequency Sleep/POR INTRC INTOSC 31 kHz 125 kHz-8 MHz Sleep EC, RC DC – 20 MHz LFINTOSC (31 kHz) EC, RC DC – 20 MHz Sleep/POR LP, XT, HS 31 kHz-20 MHz 1024 Clock Cycles (OST) LFINTOSC (31 kHz) INTOSC 125 kHz-8 MHz 1 μs (approx.) Note 1: 3.3.2 Oscillator Delay Comments 5 μs-10 μs (approx.) CPU Start-up(1) Following a wake-up from Sleep mode or POR, CPU start-up is invoked to allow the CPU to become ready for code execution. The 5 μs-10 μs start-up delay is based on a 1 MHz System Clock. EC MODE FIGURE 3-2: The External Clock (EC) mode allows an externally generated logic level as the system clock source. When operating in this mode, an external clock source is connected to OSC1 pin and the RA4 pin is available for general purpose I/O. Figure 3-2 shows the pin connections for EC mode. EXTERNAL CLOCK (EC) MODE OPERATION OSC1/CLKIN PIC16F785 Clock from Ext. System RA4 I/O (OSC2) The Oscillator Start-up Timer (OST) is disabled when EC mode is selected. Therefore, there is no delay in operation after a Power-on Reset (POR) or wake-up from Sleep. Because the PIC16F785 design is fully static, stopping the external clock input will have the effect of halting the device while leaving all data intact. Upon restarting the external clock, the device will resume operation as if no time had elapsed. DS41249B-page 24 Preliminary © 2005 Microchip Technology Inc. PIC16F785 3.3.3 FIGURE 3-4: LP, XT, HS MODES The LP, XT and HS modes support the use of quartz crystal resonators or ceramic resonators connected to the OSC1 and OSC2 pins (Figure 3-1). The mode selects a low, medium, or high gain setting of the internal inverter-amplifier to support various resonator types and speed. LP Oscillator mode selects the lowest gain setting of the internal inverter-amplifier. LP mode current consumption is the least of the three modes. This mode is best suited to drive resonators with a low drive level specification, for example, tuning fork type crystals. XT Oscillator mode selects the intermediate gain setting of the internal inverter-amplifier. XT mode current consumption is the medium of the three modes. This mode is best suited to drive resonators with a medium drive level specification, for example, AT-cut quartz crystal resonators. HS Oscillator mode selects the highest gain setting of the internal inverter-amplifier. HS mode current consumption is the highest of the three modes. This mode is best suited for resonators that require a high drive setting, for example, AT-cut quartz crystal resonators or ceramic resonators. CERAMIC RESONATOR OPERATION (XT OR HS MODE) OSC1 PIC16F785 C1 RP(3) RF(2) Sleep OSC2 RS(1) C2 Ceramic Resonator To Internal Logic Note 1: A series resistor (RS) may be required for ceramic resonators with low drive level. 2: The value of RF varies with the Oscillator mode selected (typically between 2 MΩ to 10 MΩ). 3: An additional parallel feedback resistor (RP) may be required for proper ceramic resonator operation (typical value 1 MΩ). Figure 3-3 and Figure 3-4 show typical circuits for quartz crystal and ceramic resonators, respectively. FIGURE 3-3: QUARTZ CRYSTAL OPERATION (LP, XT OR HS MODE) OSC1 PIC16F785 C1 Quartz Crystal OSC2 RF(2) Sleep RS(1) C2 To Internal Logic Note 1: A series resistor (RS) may be required for quartz crystals with low drive level. 2: The value of RF varies with the Oscillator mode selected (typically between 2 MΩ to 10 MΩ). Note 1: Quartz crystal characteristics vary according to type, package and manufacturer. The user should consult the manufacturer data sheets for specifications and recommended application. 2: Always verify oscillator performance over the VDD and temperature range that is expected for the application. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 25 PIC16F785 TABLE 3-2: Mode CERAMIC RESONATORS 3.3.4 Freq OSC1 (C1) OSC2 (C2) XT 455 kHz 2.0 MHz 68-100 pF 15-68 pF 68-100 pF 15-68 pF HS 4.0 MHz 8.0 MHz 16.0 MHz 10-68 pF 15-68 pF 10-22 pF 10-68 pF 15-68 pF 10-22 pF Note: These values are for design guidance only. See notes following this table. TABLE 3-3: CAPACITOR SELECTION FOR CRYSTAL OSCILLATOR Crystal Freq Cap. Range C1 LP 32 kHz 15-33 pF 15-33 pF XT 200 kHz 47-68 pF 47-68 pF 1 MHz 15-33 pF 15-33 pF 4 MHz 15-33 pF 15-33 pF 4 MHz 15-33 pF 15-33 pF 8 MHz 15-33 pF 15-33 pF 20 MHz 15-33 pF 15-33 pF Osc Type HS Note: Cap. Range C2 These values are for design guidance only. See notes following this table. Note 1: Higher capacitance increases the stability of the oscillator, but also increases the start-up time. 2: Since each resonator/crystal has its own characteristics, the user should consult the resonator/crystal manufacturer for appropriate values of external components. 3: RS may be required to avoid overdriving crystals with low drive level specification. EXTERNAL RC MODES The External Resistor-Capacitor (RC) modes support the use of an external RC circuit. This allows the designer maximum flexibility in frequency choice while keeping costs to a minimum when clock accuracy is not required. There are two modes, RC and RCIO. In RC mode, the RC circuit connects to the OSC1 pin. The OSC2/CLKOUT pin outputs the RC oscillator frequency divided by 4. This signal may be used to provide a clock for external circuitry, synchronization, calibration, test or other application requirements. Figure 3-5 shows the RC mode connections. FIGURE 3-5: RC MODE VDD REXT Internal Clock OSC1 CEXT PIC16F785 VSS OSC2/CLKOUT FOSC/4 Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ (VDD ≥ 3.0V) 10 kΩ ≤ L ≤ 100 kΩ (VDD < 3.0V) CEXT > 20 pF In RCIO mode, the RC circuit is connected to the OSC1 pin. The OSC2 pin becomes an additional general purpose I/O pin. The I/O pin becomes bit 4 of PORTA (RA4). Figure 3-6 shows the RCIO mode connections. FIGURE 3-6: RCIO MODE VDD REXT OSC1 Internal Clock CEXT PIC16F785 VSS RA4 I/O (OSC2) Recommended values: 3 kΩ ≤ REXT ≤ 100 kΩ (VDD ≥ 3.0V) 10 kΩ ≤ REXT ≤ 100 kΩ (VDD < 3.0V) CEXT > 20 pF The RC oscillator frequency is a function of the supply voltage, the resistor (REXT) and capacitor (CEXT) values and the operating temperature. In addition to this, the oscillator frequency will vary from unit-to-unit due to normal threshold voltage. Furthermore, the difference in lead frame capacitance between package types will also affect the oscillation frequency or low CEXT values. The user also needs to take into account variation due to tolerance of external RC components used. DS41249B-page 26 Preliminary © 2005 Microchip Technology Inc. PIC16F785 3.4 3.4.2.1 Internal Clock Modes The PIC16F785 has two independent, internal oscillators that can be configured or selected as the system clock source. 1. 2. The HFINTOSC (High-frequency Internal Oscillator) is factory calibrated and operates at 8 MHz. The frequency of the HFINTOSC can be user adjusted ±12% via software using the OSCTUNE register (Register 3-1). The LFINTOSC (Low-frequency Internal Oscillator) is uncalibrated and operates at approximately 31 kHz. The system clock speed can be selected via software using the Internal Oscillator Frequency Select (IRCF) bits. The 8 MHz High-frequency Internal Oscillator (HFINTOSC) is factory calibrated. The HFINTOSC calibration bits are stored in the Calibration Word (CALIB) located in program memory location 2008h. The Calibration Word is not erased using the specified bulk erase sequence in the “PIC16F785/PS200 Memory Programming Specification” (DS41237) and does not require reprogramming. Reference the “PIC16F785/ PS200 Memory Programming Specification” (DS41237) for more information on the Calibration Word register. Note: The system clock can be selected between external or internal clock sources via the System Clock Selection (SCS) bit (see Section 3.5 “Clock Switching”). 3.4.1 Calibration Bits Address 2008h is beyond the user program memory space. It belongs to the special Configuration Memory space (2000h3FFFh), which can be accessed only during programming. See “PIC16F785/PS200 Memory Programming Specification” (DS41237) for more information. INTRC AND INTRCIO MODES The INTRC and INTRCIO modes configure the internal oscillators as the system clock source when the device is programmed using the Oscillator Selection (FOSC) bits in the Configuration Word (Register 12-1). In INTRC mode, the OSC1 pin is available for general purpose I/O. The OSC2/CLKOUT pin outputs the selected internal oscillator frequency divided by 4. The CLKOUT signal may be used to provide a clock for external circuitry, synchronization, calibration, test or other application requirements. In INTRCIO mode, the OSC1 and OSC2 pins are available for general purpose I/O. 3.4.2 HFINTOSC The High-frequency Internal Oscillator (HFINTOSC) is a factory calibrated 8 MHz internal clock source. The frequency of the HFINTOSC can be altered approximately ±12% via software using the OSCTUNE register (Register 3-1). The output of the HFINTOSC connects to a postscaler and multiplexer (see Figure 3-1). One of seven frequencies can be selected via software using the IRCF bits (see Section 3.4.4 “Frequency Select Bits (IRCF)”). The HFINTOSC is enabled by selecting any frequency between 8 MHz and 125 kHz (IRCF ≠ 000) as the system clock source (SCS = 1) or when Two-Speed Start-up is enabled (IESO = 1 and IRCF ≠ 000). The HF Internal Oscillator (HTS) bit, (OSCCON<2>), indicates whether the HFINTOSC is stable or not. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 27 PIC16F785 3.4.2.2 OSCTUNE Register The HFINTOSC is factory calibrated but can be adjusted in software by writing to the OSCTUNE register (Register 3-1). The OSCTUNE register has a tuning range of ±12%. The default value of the OSCTUNE register is ‘0’. The value is a 5-bit two’s complement number. Due to process variation, the monotonicity and frequency step cannot be specified. REGISTER 3-1: When the OSCTUNE register is modified, the HFINTOSC frequency will begin shifting to the new frequency. The HFINTOSC clock will stabilize within 1 ms. Code execution continues during this shift. There is no indication that the shift has occurred. OSCTUNE does not affect the LFINTOSC frequency. Operation of features that depend on the LFINTOSC clock source frequency, such as the Power-up Timer (PWRT), Watchdog Timer (WDT), Fail-Safe Clock Monitor (FSCM) and peripherals, are not affected by the change in frequency. OSCTUNE – OSCILLATOR TUNING REGISTER (ADDRESS 90h) U-0 U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — — — TUN4 TUN3 TUN2 TUN1 TUN0 bit 7 bit 7-5 bit 4-0 Unimplemented: Read as ‘0’ TUN<4:0>: Frequency Tuning bits 01111 = Maximum frequency 01110 = • • • 00001 = 00000 = Center frequency. Oscillator module is running at the calibrated frequency. 11111 = • • • 10000 = Minimum frequency Legend: R = Readable bit - n = Value at POR DS41249B-page 28 bit 0 W = Writable bit ‘1’ = Bit is set Preliminary U = Unimplemented bit, read as ‘0’ ‘0’ = Bit is cleared x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 3.4.3 LFINTOSC 3.4.5 The Low-frequency Internal Oscillator (LFINTOSC) is an uncalibrated (approximate) 31 kHz internal clock source. The output of the LFINTOSC connects to a postscaler and multiplexer (see Figure 3-1). 31 kHz can be selected via software using the IRCF bits (see Section 3.4.4 “Frequency Select Bits (IRCF)”). The LFINTOSC is also the frequency for the Power-up Timer (PWRT), Watchdog Timer (WDT) and Fail-Safe Clock Monitor (FSCM). The LFINTOSC is enabled by selecting 31 kHz (IRCF = 000) as the system clock source (SCS = 1), or when any of the following are enabled: • • • • Two-Speed Start-up (IESO = 1 and IRCF = 000) Power-up Timer (PWRT) Watchdog Timer (WDT) Fail-Safe Clock Monitor (FSCM) 3.4.4 1. 2. IRCF bits are modified. If the new clock is shut down, a 10 μs clock startup delay is started. Clock switch circuitry waits for a falling edge of the current clock. CLKOUT is held low and the clock switch circuitry waits for a rising edge in the new clock. CLKOUT is now connected with the new clock. HTS/LTS bits are updated as required. Clock switch is complete. 3. 5. FREQUENCY SELECT BITS (IRCF) The output of the 8 MHz HFINTOSC and 31 kHz LFINTOSC connect to a postscaler and multiplexer (see Figure 3-1). The Internal Oscillator Frequency select bits IRCF<2:0> (OSCCON<6:4>) select the frequency output of the internal oscillators. One of eight frequencies can be selected via software: • • • • • • • • When switching between the LFINTOSC and the HFINTOSC, the new oscillator may already be shut down to save power. If this is the case, there is a 10 μs delay after the IRCF bits are modified before the frequency selection takes place. The LTS/HTS bits will reflect the current active status of the LFINTOSC and the HFINTOSC oscillators. The timing of a frequency selection is as follows: 4. The LF Internal Oscillator (LTS) bit, (OSCCON<1>), indicates whether the LFINTOSC is stable or not. 6. If the internal oscillator speed selected is between 8 MHz and 125 kHz, there is no start-up delay before the new frequency is selected. This is because the old and the new frequencies are derived from the HFINTOSC via the postscaler and multiplexer. Note: 8 MHz 4 MHz (Default after Reset) 2 MHz 1 MHz 500 kHz 250 kHz 125 kHz 31 kHz Note: HF AND LF INTOSC CLOCK SWITCH TIMING Care must be taken to ensure an invalid voltage or frequency selection is not selected. An example of an invalid configuration is selecting 8 MHz when VDD is 2.0V. Following any Reset, the IRCF bits are set to ‘110’ and the frequency selection is forced to 4 MHz. The user can modify the IRCF bits to select a different frequency. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 29 PIC16F785 3.5 Clock Switching The system clock source can be switched between external and internal clock sources via software using the System Clock Select (SCS) bit. 3.5.1 SYSTEM CLOCK SELECT (SCS) BIT The System Clock Select (SCS) bit, (OSCCON<0>), selects the system clock source that is used for the CPU and peripherals. • When SCS = 0, the system clock source is determined by configuration of the FOSC<2:0> bits in Configuration Word (CONFIG). • When SCS = 1, the system clock source is chosen by the internal oscillator frequency selected by the IRCF bits. After a Reset, SCS is always cleared. Note: 3.5.2 3.6.1 Any automatic clock switch, which may occur from Two-Speed Start-up or Fail-Safe Clock Monitor, does not update the SCS bit. The user can monitor the OSTS (OSCCON<3>) to determine the current system clock source. OSCILLATOR START-UP TIME-OUT STATUS BIT Two-Speed Clock Start-up Mode Two-Speed Start-up mode provides additional power savings by minimizing the latency between external oscillator start-up and code execution. In applications that make heavy use of the Sleep mode, Two-Speed Start-up will remove the external oscillator start-up time from the time spent awake and can reduce the overall power consumption of the device. This mode allows the application to wake-up from Sleep, perform a few instructions using the INTOSC as the clock source and go back to Sleep without waiting for the primary oscillator to become stable. Note: Executing a SLEEP instruction will abort the Oscillator Start-up Time and will cause the OSTS bit (OSCCON<3>) to remain clear. DS41249B-page 30 TWO-SPEED START-UP MODE CONFIGURATION Two-Speed Start-up mode is configured by the following settings: The Oscillator Start-up Time-out Status (OSTS) bit, (OSCCON<3>), indicates whether the system clock is running from the external clock source as defined by the FOSC bits, or from internal clock source. In particular, OSTS indicates that the Oscillator Start-up Timer (OST) has timed out for LP, XT or HS modes. 3.6 When the PIC16F785 is configured for LP, XT or HS modes, the Oscillator Start-up Timer (OST) is enabled (see Section 3.3.1 “Oscillator Start-up Timer (OST)”). The OST timer will suspend program execution until 1024 oscillations are counted. TwoSpeed Start-up mode minimizes the delay in code execution by operating from the internal oscillator as the OST is counting. When the OST count reaches 1024 and the OSTS bit (OSCCON<3>) is set, program execution switches to the external oscillator. • IESO = 1 (CONFIG<10>) Internal/External Switch Over bit. • SCS = 0. • FOSC configured for LP, XT or HS mode. Two-Speed Start-up mode is entered after: • Power-on Reset (POR) and, if enabled, after PWRT has expired, or • Wake-up from Sleep. If the external clock oscillator is configured to be anything other than LP, XT or HS mode, then TwoSpeed Start-up is disabled. This is because the external clock oscillator does not require any stabilization time after POR or an exit from Sleep. 3.6.2 1. 2. 3. 4. 5. 6. 7. TWO-SPEED START-UP SEQUENCE Wake-up from Power-on Reset or Sleep. Instructions begin execution by the internal oscillator at the frequency set in the IRCF bits (OSCCON<6:4>). OST enabled to count 1024 clock cycles. OST timed out, wait for falling edge of the internal oscillator. OSTS is set. System clock held low until the next falling edge of new clock (LP, XT or HS mode). System clock is switched to external clock source. 3.6.3 CHECKING EXTERNAL/INTERNAL CLOCK STATUS Checking the state of the OSTS bit (OSCCON<3>) will confirm if the PIC16F785 is running from the external clock source as defined by the FOSC bits in the Configuration Word (CONFIG) or the internal oscillator. Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 3-7: TWO-SPEED START-UP Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 INTOSC TOST OSC1 0 1 1022 1023 OSC2 PC Program Counter PC + 1 PC + 2 System Clock 3.7 Fail-Safe Clock Monitor The Fail-Safe Clock Monitor (FSCM) is designed to allow the device to continue to operate in the event of an oscillator failure. The FSCM can detect oscillator failure at any point after the device has exited a Reset or Sleep condition and the Oscillator Start-up Timer (OST) has expired. FIGURE 3-8: FSCM BLOCK DIAGRAM Clock Monitor Latch (CM) (edge-triggered) Primary Clock LFINTOSC Oscillator ÷ 64 31 kHz (~32 μs) 488 Hz (~2 ms) S Q C Q The frequency of the internal oscillator will depend upon the value contained in the IRCF bits (OSCCON<6:4>). Upon entering the Fail-Safe condition, the OSTS bit (OSCCON<3>) is automatically cleared to reflect that the internal oscillator is active and the WDT is cleared. The SCS bit (OSCCON<0>) is not updated. Enabling FSCM does not affect the LTS bit. The FSCM sample clock is generated by dividing the LFINTOSC clock by 64. This will allow enough time between FSCM sample clocks for a system clock edge to occur. Figure 3-8 shows the FSCM block diagram. On the rising edge of the sample clock, the monitoring latch (CM = 0) will be cleared. On a falling edge of the primary system clock, the monitoring latch will be set (CM = 1). In the event that a falling edge of the sample clock occurs, and the monitoring latch is not set, a clock failure has been detected. The assigned internal oscillator is enabled when FSCM is enabled as reflected by the IRCF bits. Note: Clock Failure Detected Two-Speed Start-up is automatically enabled when the Fail-Safe Clock Monitor mode is enabled. The FSCM function is enabled by setting the FCMEN bit in Configuration Word (CONFIG). It is applicable to all external clock options (LP, XT, HS, EC, RC or I/O modes). In the event of an external clock failure, the FSCM will set the OSFIF bit (PIR1<2>) and generate an oscillator fail interrupt if the OSFIE bit (PIE1<2>) is set. The device will then switch the system clock to the internal oscillator. The system clock will continue to come from the internal oscillator unless the external clock recovers and the Fail-Safe condition is exited. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 31 PIC16F785 3.7.1 FAIL-SAFE CONDITION CLEARING The Fail-Safe condition is cleared after a Reset, the execution of a SLEEP instruction, or a modification of the SCS bit. While in Fail-Safe condition, the PIC16F785 uses the internal oscillator as the system clock source. The IRCF bits (OSCCON<6:4>) can be modified to adjust the internal oscillator frequency without exiting the Fail-Safe condition. The Fail-Safe condition must be cleared before the OSFIF flag can be cleared. FIGURE 3-9: FSCM TIMING DIAGRAM Sample Clock Oscillator Failure System Clock Output CM Output (Q) Failure Detected OSCFIF CM Test Note: 3.7.2 CM Test CM Test The system clock is normally at a much higher frequency than the sample clock. The relative frequencies in this example have been chosen for clarity. RESET OR WAKE-UP FROM SLEEP The FSCM is designed to detect oscillator failure at any point after the device has exited a Reset or Sleep condition and the Oscillator Start-up Timer (OST) has expired. If the external clock is EC or RC mode, monitoring will begin immediately following these events. For LP, XT or HS mode, the external oscillator may require a start-up time considerably longer than the FSCM sample clock time; a false clock failure may be detected (see Figure 3-9). To prevent this, the internal oscillator is automatically configured as the system clock and functions until the external clock is stable (the OST has timed out). This is identical to TwoSpeed Start-up mode. Once the external oscillator is stable, the LFINTOSC returns to its role as the FSCM source. Note: Due to the wide range of oscillator start-up times, the Fail-Safe circuit is not active during oscillator start-up (i.e., after exiting Reset or Sleep). After an appropriate amount of time, the user should check the OSTS bit (OSCCON<3>) to verify the oscillator start-up and system clock switchover has successfully completed. DS41249B-page 32 Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 3-2: OSCCON – OSCILLATOR CONTROL REGISTER (ADDRESS: 8Fh) U-0 R/W-1 R/W-1 R/W-0 R-q R-0 R-0 R/W-0 — IRCF2 IRCF1 IRCF0 OSTS(1) HTS LTS SCS bit 7 bit 7 bit 6-4 bit 0 Unimplemented: Read as ‘0’ IRCF<2:0>: Internal Oscillator Frequency Select bits 000 = 31 kHz 001 = 125 kHz 010 = 250 kHz 011 = 500 kHz 100 = 1 MHz 101 = 2 MHz 110 = 4 MHz 111 = 8 MHz OSTS: Oscillator Start-up Time-out Status bit(1) 1 = Device is running from the external system clock defined by FOSC<2:0> 0 = Device is running from the internal system clock (HFINTOSC or LFINTOSC) HTS: HFINTOSC (High Frequency – 8 MHz to 125 kHz) Status bit 1 = HFINTOSC is stable 0 = HFINTOSC is not stable LTS: LFINTOSC (Low Frequency – 31 kHz) Stable bit 1 = LFINTOSC is stable 0 = LFINTOSC is not stable SCS: System Clock Select bit 1 = Internal oscillator is used for system clock 0 = Clock source defined by FOSC<2:0> bit 3 bit 2 bit 1 bit 0 Note 1: Bit resets to ‘0’ with Two-Speed Start-up and LP, XT or HS selected as the Oscillator mode or Fail-Safe mode is enabled, otherwise this bit resets to ‘1’. Legend: q = value depends on condition 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 TABLE 3-4: Address SUMMARY OF REGISTERS ASSOCIATED WITH CLOCK SOURCES Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets 0000 0000 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 8Fh OSCCON — IRCF2 IRCF1 IRCF0 OSTS HTS LTS SCS -110 q000 -110 q000 90h OSCTUNE 2007h(1) CONFIG Legend: Note 1: — — — TUN4 TUN3 TUN2 TUN1 TUN0 ---0 0000 ---u uuuu CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 — — x = unknown, u = unchanged, – = unimplemented locations read as ‘0’, q = value depends on condition. Shaded cells are not used by oscillators. See Register 15-1 for operation of all Configuration Word bits. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 33 PIC16F785 NOTES: DS41249B-page 34 Preliminary © 2005 Microchip Technology Inc. PIC16F785 4.0 I/O PORTS There are seventeen general purpose I/O pins and one input only pin available. Depending on which peripherals are enabled, some or all of the pins may not be available as general purpose I/O. In general, when a peripheral is enabled, the associated pin may not be used as a general purpose I/O pin. Note: 4.1 Additional information on I/O ports may be found in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). 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. I/O pins configured as analog inputs always read ‘0’. When RA1 is configured as a voltage reference output, the RA1 digital output driver will automatically be disabled while not affecting the TRISA<1> value. Note: PORTA and TRISA Registers PORTA is a 6-bit wide, bidirectional port. The corresponding data direction register is TRISA (Register 4-2). Setting a TRISA bit (= 1) will make the corresponding PORTA pin an input (i.e., 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). The exception is RA3, which is input only and its TRIS bit will always read as ‘1’. Example 4-1 shows how to initialize PORTA. EXAMPLE 4-1: Reading the PORTA register (Register 4-1) reads the status of the pins, whereas writing to it will write to the port latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read; this value is modified and then written to the port data latch. RA3 reads ‘0’ when MCLRE = 1. REGISTER 4-1: The ANSEL0 (91h) register must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. INITIALIZING PORTA BCF BCF CLRF MOVLW ANDWF BSF MOVLW MOVWF STATUS,RP0 STATUS,RP1 PORTA F8h ANSEL0,f STATUS,RP0 0Ch TRISA BCF STATUS,RP0 ;Bank 0 ; ;Init PORTA ;Set RA<2:0> to ; digital I/O ;Bank 1 ;Set RA<3:2> as inputs ; and set RA<5:4,1:0> ; as outputs ;Bank 0 PORTA – PORTA REGISTER (ADDRESS: 05h, 105h) U-0 U-0 R/W-x R/W-x(1) R/W-x R/W-x(1) R/W-x(1) R/W-x(1) — — RA5 RA4 RA3 RA2 RA1 RA0 bit 7 bit 0 bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 RA<5:0>: PORTA I/O Pin bits 1 = Port pin is greater than VIH 0 = Port pin is less than VIL Note 1: Data latches are unknown after a POR, but each port bit reads ‘0’ when the corresponding analog select bit is ‘1’ (see Register 12-1). Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 35 PIC16F785 REGISTER 4-2: TRISA – PORTA TRI-STATE REGISTER (ADDRESS: 85h, 185h) U-0 U-0 — — R/W-1 R/W-1 R-1 TRISA5(2) TRISA4(2) TRISA3(1) R/W-1 R/W-1 R/W-1 TRISA2 TRISA1 TRISA0 bit 7 bit 0 bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 TRISA<5:0>: PORTA Tri-State Control bit(1, 2) 1 = PORTA pin configured as an input (tri-stated) 0 = PORTA pin configured as an output Note 1: TRISA<3> always reads ‘1’. 2: TRISA<5:4> always reads ‘1’ in XT, HS and LP OSC modes. Legend: 4.2 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Additional Pin Functions 4.2.1 Every PORTA pin on the PIC16F785 has an interrupton-change option and a weak pull-up option. The next three sections describe these functions. REGISTER 4-3: x = Bit is unknown WEAK PULL-UPS Each of the PORTA pins has an individually configurable internal weak pull-up. Control bits WPUAx enable or disable each pull-up. Refer to Register 4-3. Each 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 by the RAPU bit (OPTION_REG<7>). The weak pull-up on RA3 is automatically enabled when RA3 is configured as MCLR. WPUA – WEAK PULL-UP REGISTER (ADDRESS: 95h)(1, 2) U-0 U-0 — — R/W-1 R/W-1 R/W-1 WPUA5(4) WPUA4(4) WPUA3(3) R/W-1 R/W-1 R/W-1 WPUA2 WPUA1 WPUA0 bit 7 bit 0 bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 WPUA<5:0>: Weak Pull-up Register bits 1 = Pull-up enabled 0 = Pull-up disabled Note 1: Global RAPU must be enabled for individual pull-ups to be enabled. 2: The weak pull-up device is automatically disabled if the pin is in Output mode (TRISA = 0). 3: The RA3 pull-up is automatically enabled when configured as MCLR in the Configuration Word. 4: WPUA<5:4> always reads ‘1’ in XT, HS and LP OSC modes. Legend: DS41249B-page 36 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 4.2.2 INTERRUPT-ON-CHANGE Each of the PORTA pins is individually configurable as an interrupt-on-change pin. Control bits IOCAx enable or disable the interrupt function for each pin. Refer to Register 4-4. The interrupt-on-change is disabled on a Power-on Reset. For enabled interrupt-on-change pins, the values are compared with the old value latched on the last read of PORTA. The ‘mismatch’ outputs of the last read are OR'd together to set, the PORTA Change Interrupt flag bit (RAIF) in the INTCON register (Register 2-3). This interrupt can wake the device from Sleep. The user, in the Interrupt Service Routine, clears the interrupt by: a) Any read or write of PORTA. This will end the mismatch condition, then, Clear the flag bit RAIF. b) A mismatch condition will continue to set flag bit RAIF. Reading PORTA will end the mismatch condition and allow flag bit RAIF to be cleared. The latch holding the last read value is neither affected by an MCLR nor BOR Reset. After these resets, the RAIF flag will continue to be set if a mismatch is present. Note: REGISTER 4-4: If a change on the I/O pin should occur when the read operation is being executed (start of the Q2 cycle), then the RAIF interrupt flag may not get set. IOCA – INTERRUPT-ON-CHANGE PORTA REGISTER (ADDRESS: 96h)(1) U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — — IOCA5(2) IOCA4(2) IOCA3 IOCA2 IOCA1 IOCA0 bit 7 bit 0 bit 7-6 Unimplemented: Read as ‘0’ bit 5-0 IOCA<5:0>: Interrupt-on-change PORTA Control bits(2) 1 = Interrupt-on-change enabled 0 = Interrupt-on-change disabled Note 1: Global interrupt enable (GIE) must be enabled for individual interrupts to be recognized. 2: IOCA<5:4> always reads ‘1’ in XT, HS and LP OSC modes. 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 37 PIC16F785 4.2.3 PORTA PIN DESCRIPTIONS AND DIAGRAMS Each PORTA pin is multiplexed with other functions. The pins and their combined functions are briefly described here. For specific information about individual functions such as the comparator or the A/D, refer to the appropriate section in this Data Sheet. 4.2.3.1 RA0/AN0/C1IN+/ICSPDAT Figure 4-1 shows the diagram for this pin. The RA0 pin is configurable to function as one of the following: • • • • Data Bus WR WPUA a general purpose I/O an analog input for the A/D an analog input to Comparators 1 and 2 a voltage reference input for the A/D a buffered or unbuffered voltage reference output In-Circuit Serial Programming clock Weak D Weak Q CK Q RAPU RD WPUA D WR PORTA D CK Q I/O pin D CK Q D VDD Q VDD Q I/O pin WR TRISA VDD RAPU RD WPUA WR PORTA BLOCK DIAGRAM OF RA1 ANS1 Data Bus WR WPUA VDD CK Q • • • • • • VROE*VREN CVROE BLOCK DIAGRAM OF RA0 Q Figure 4-1 shows the diagram for this pin. The RA1 pin is configurable to function as one of the following: VROUT ANS0 D RA1/AN1/C12IN0-/VREF/ICSPCLK FIGURE 4-2: a general purpose I/O an analog input for the A/D an analog input to Comparator 1 In-Circuit Serial Programming™ data FIGURE 4-1: 4.2.3.2 WR TRISA Q CK Q VSS Q CK Q RD TRISA VSS ANS0 RD PORTA RD TRISA Q D D Q EN RD PORTA Q D WR IOCA D Q D Q EN WR IOCA CK Q RD IOCA CK Q Q RD IOCA D EN Q Q Q1 Q1 D Q3 Interrupt-onchange EN D Q3 Interrupt-onchange EN EN RD PORTA To Comparators To A/D Converter RD PORTA To Comparator To A/D Converter DS41249B-page 38 Preliminary © 2005 Microchip Technology Inc. PIC16F785 4.2.3.3 4.2.3.4 RA2/AN2/T0CKI/INT/C1OUT RA3/MCLR/VPP Figure 4-3 shows the diagram for this pin. The RA2 pin is configurable to function as one of the following: Figure 4-4 shows the diagram for this pin. The RA3 pin is configurable to function as one of the following: • • • • • • a general purpose input • as Master Clear Reset with weak pull-up a general purpose I/O an analog input for the A/D the clock input for TMR0 an external edge triggered interrupt a digital output from Comparator 1 FIGURE 4-4: Data Bus D BLOCK DIAGRAM OF RA3 Q MCLRE VDD FIGURE 4-3: BLOCK DIAGRAM OF RA2 C1OE ANS2 WR WPUA D CK Weak Q Q RAPU MCLRE Input pin VSS MCLRE D RAPU Weak Reset RD PORTA WR IOCA CK VSS Q Q D Q EN D CK VDD Q Q D CK RD IOCA Q 1 D EN 0 WR TRISA Q RD TRISA VDD RD WPUA WR PORTA CK RD WPUA C1OUT Data Bus WR WPUA I/O pin Interrupt-onChange Q Q1 D Q Q3 EN Q VSS RD PORTA ANS2 RD TRISA RD PORTA Q D D Q EN WR IOCA CK Q Q RD IOCA D EN Q Q1 D Q3 Interrupt-onChange EN RD PORTA To TMR0 To INT To A/D Converter © 2005 Microchip Technology Inc. Preliminary DS41249B-page 39 PIC16F785 4.2.3.5 4.2.3.6 RA4/AN3/T1G/OSC2/CLKOUT RA5/T1CKI/OSC1/CLKIN Figure 4-5 shows the diagram for this pin. The RA4 pin is configurable to function as one of the following: Figure 4-6 shows the diagram for this pin. The RA5 pin is configurable to function as one of the following: • • • • • • • • • a general purpose I/O an analog input for the A/D a TMR1 gate input a crystal/resonator connection a clock output a general purpose I/O a TMR1 clock input a crystal/resonator connection a clock input FIGURE 4-6: FIGURE 4-5: ANS3 Data Bus WR WPUA D CK BLOCK DIAGRAM OF RA5 BLOCK DIAGRAM OF RA4 INTOSC Mode CLK(1) Modes Q VDD Q Data Bus Weak WR WPUA D CLK modes(1) VDD Q CK Weak Q RAPU RD WPUA Oscillator Circuit VDD OSC1 RAPU RD WPUA VDD Oscillator Circuit OSC2 FOSC/4 D WR PORTA CK D 0 Q Q 1 I/O pin CLKOUT Enable INTOSC/ RC/EC(2) CK CK INTOSC Mode RD TRISA (2) ANS3 RD PORTA RD PORTA D CK Q Q CLKOUT Enable D I/O pin Q D S Q WR TRISA RD TRISA WR IOCA CK VSS VSS D S Q WR TRISA WR PORTA Q Q Q WR IOCA EN Q Q RD IOCA Q Q D EN Q D EN Q1 Q D EN Q1 D Q3 Interrupt-onChange Q3 Interrupt-onCHANGE CK RD IOCA D EN Q Q D EN RD PORTA RD PORTA To TMR1 or CLKGEN To T1G To A/D Converter Note Note 1: CLK modes are XT, HS, LP, LPTMR1 and CLKOUT Enable. 1: CLK modes are XT, HS, LP and LPTMR1. 2: When using Timer1 with LP oscillator, the Schmitt Trigger is bypassed. 2: With CLKOUT option. DS41249B-page 40 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 4-1: Addr SUMMARY OF REGISTERS ASSOCIATED WITH PORTA Name Bit 7 05h, 105h PORTA — 10h T1CON T1GINV 0Bh, 8Bh INTCON 81h, 181h OPTION_REG 85h, 185h TRISA 91h ANSEL0 95h 96h Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 — RA5 RA4 RA3 RA2 RA1 RA0 TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON Value on: POR, BOR Value on all other Resets --xx xxxx --uu uuuu 0000 0000 0000 0000 GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111 — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 WPUA — — WPUA5 WPUA4 WPUA3 WPUA2 WPUA1 WPUA0 --11 1111 --11 1111 IOCA — — IOCA5 IOCA4 IOCA3 IOCA2 IOCA1 IOCA0 --00 0000 --00 0000 — — BGST VRBB VREN VROE CVROE — --00 000- --00 000- C1ON C1OUT C1OE C1POL C1SP C1R C1CH1 C1CH0 0000 0000 0000 0000 — — — — T1GSS C2SYNC 00-- --10 00-- --10 98h REFCON 119h CM1CON0 11Bh CM2CON1 Legend: Bit 6 MC1OUT MC2OUT x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTA. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 41 PIC16F785 4.3 PORTB and TRISB Registers PORTB is a 4-bit wide, bidirectional port. The corresponding data direction register is TRISB (Register 4-6). 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). Example 4-2 shows how to initialize PORTB. Reading the PORTB register (Register 4-5) reads the status of the pins, whereas writing to it will write to the port latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the port data latch. The TRISB register controls the direction of the PORTB pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISB register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. Note: EXAMPLE 4-2: Pin RB6 is an open drain output. All other PORTB pins have full CMOS output drivers. REGISTER 4-5: The ANSEL1 (93h) register must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. BCF BCF CLRF BSF BCF BCF MOVLW MOVWF STATUS,RP0 STATUS,RP1 PORTB STATUS,RP0 ANSEL1,2 ANSEL1,3 30h TRISB BCF STATUS,RP0 INITIALIZING PORTB ;Bank 0 ; ;Init PORTB ;Bank 1 ;digital I/O - RB4 ;digital I/O - RB5 ;Set RB<5:4> as inputs ;and set RB<7:6> ;as outputs ;Bank 0 PORTB – PORTB REGISTER (ADDRESS: 06h, 106h) R/W-x R/W-x R/W-x(1) R/W-x(1) U-0 U-0 U-0 U-0 RB7 RB6 RB5 RB4 — — — — bit 7 bit 0 bit 7-4 RB<7:4>: PORTB General Purpose I/O Pin bits 1 = Port pin is greater than VIH 0 = Port pin is less than VIL bit 3-0 Unimplemented: Read as ‘0’ Note 1: Data latches are unknown after a POR, but each port bit reads ‘0’ when the corresponding analog select bit is ‘1’ (see Register 12-2 on page 82). Legend: REGISTER 4-6: 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 TRISB – PORTB TRI-STATE REGISTER (ADDRESS: 86h, 186h) R/W-1 R/W-1 R/W-1 R/W-1 U-0 U-0 U-0 U-0 TRISB7 TRISB6 TRISB5 TRISB4 — — — — bit 7 bit 0 bit 7-4 TRISB<7:4>: PORTB Tri-State Control bits 1 = PORTB pin configured as an input (tri-stated) 0 = PORTB pin configured as an output bit 3-0 Unimplemented: Read as ‘0’ Legend: DS41249B-page 42 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 4.3.1 PORTB PIN DESCRIPTIONS AND DIAGRAMS Each PORTB pin is multiplexed with other functions. The pins and their combined functions are briefly described here. For specific information about individual functions such as the PWM, operational amplifier, or the A/D, refer to the appropriate section in this Data Sheet. 4.3.1.1 • a general purpose I/O • an analog input to the A/D • an analog input to Op Amp 2 4.3.1.2 The RB6 pin is configurable to function as the following: • an open drain general purpose I/O FIGURE 4-8: BLOCK DIAGRAM OF RB6 Data Bus WR PORTB Q CK Q I/O Pin N WR TRISB RB5/AN11/OP2+ Q CK Q VSS VSS RD TRISB Q • a general purpose I/O • an analog input to the A/D • an analog input to Op Amp 2 FIGURE 4-7: D D The RB5/AN11/OP2+ pin is configurable to function as one of the following: D EN RD PORTB BLOCK DIAGRAM OF RB4 AND RB5 4.3.1.4 RB7/SYNC The RB7/SYNC pin is configurable to function as one of the following: Data Bus D CK • a general purpose I/O • PWM synchronization input and output VDD Q Q FIGURE 4-9: I/O Pin D WR TRISB RB6 RB4/AN10/OP2- The RB4/AN10/OP2- pin is configurable to function as one of the following: WR PORTB 4.3.1.3 CK Q BLOCK DIAGRAM OF RB7 PH1EN PH2EN PWM Master Q VSS ANS10 (RB4) ANS11 (RB5) RD TRISB Q Sync out Data Bus D D EN WR PORTB CK VDD Q Q 1 RD PORTB 0 D To A/D Converter To Op Amp 2 WR TRISB CK I/O Pin Q Q VSS RD TRISB Q D EN RD PORTB to PWM Sync Input © 2005 Microchip Technology Inc. Preliminary DS41249B-page 43 PIC16F785 TABLE 4-2: Address SUMMARY OF REGISTERS ASSOCIATED WITH PORTB Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets uuuu ---- 06h, 106h PORTB RB7 RB6 RB5 RB4 — — — — xxxx ---- 86h, 186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 — — — — 1111 ---- 1111 ---- 93h ANSEL1 — — — — ANS11 ANS10 ANS9 ANS8 ---- 1111 ---- 1111 111h PWMCON0 PRSEN PASEN BLANK2 BLANK1 SYNC1 SYNC0 PH2EN PH1EN 0000 0000 0000 0000 11Dh OPA2CON OPAON — — — — — — — 0--- ---- 0--- ---- Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTB. DS41249B-page 44 Preliminary © 2005 Microchip Technology Inc. PIC16F785 4.4 PORTC and TRISC Registers PORTC is an 8-bit wide, bidirectional port. The corresponding data direction register is TRISC (Register 4-8). 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). Example 4-3 shows how to initialize PORTC. Reading the PORTC register (Register 4-7) reads the status of the pins, whereas writing to it will write to the port latch. All write operations are read-modify-write operations. Therefore, a write to a port implies that the port pins are read, this value is modified and then written to the port data latch. The TRISC register controls the direction of the PORTC pins, even when they are being used as analog inputs. The user must ensure the bits in the TRISC register are maintained set when using them as analog inputs. I/O pins configured as analog input always read ‘0’. REGISTER 4-7: When RC4 or RC5 is configured as an op amp output, the corresponding RC4 or RC5 digital output driver will automatically be disabled regardless of the TRISC<4> or TRISC<5> value. Note: The ANSEL0 (91h) and ANSEL1 (93h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. EXAMPLE 4-3: INITIALIZING PORTC BCF BCF CLRF BSF CLRF CLRF MOVLW MOVWF STATUS,RP0 STATUS,RP1 PORTC STATUS,RP0 ANSEL0 ANSEL1 0Ch TRISC BCF STATUS,RP0 ;Bank 0 ;Init PORTC ;Bank 1 ;digital I/O ;digital I/O ;Set RC<3:2> as inputs ; and set RC<5:4,1:0> ; as outputs ;Bank 0 PORTC – PORTC REGISTER (ADDRESS: 07h, 107h) R/W-x(1) R/W-x(1) R/W-x R/W-x R/W-x(1) R/W-x(1) R/W-x(1) R/W-x(1) RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 bit 7 bit 7-0 bit 0 RC<7:0>: PORTC General Purpose I/O Pin bits 1 = Port pin is greater than VIH 0 = Port pin is less than VIL Note 1: Data latches are unknown after a POR, but each port bit reads ‘0’ when the corresponding analog select bit is ‘1’ (see Registers 12-1 and 12-2 on page 82). Legend: REGISTER 4-8: 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 TRISC – PORTC TRI-STATE REGISTER (ADDRESS: 87h, 187h) R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 bit 7 bit 7-0 bit 0 TRISC<7:0>: PORTC Tri-State Control bits 1 = PORTC pin configured as an input (tri-stated) 0 = PORTC pin configured as an output Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 45 PIC16F785 4.4.1 PORTC PIN DESCRIPTIONS AND DIAGRAMS Each PORTC pin is multiplexed with other functions. The pins and their combined functions are briefly described here. For specific information about individual functions such as the comparator or the A/D, refer to the appropriate section in this Data Sheet. 4.4.1.1 4.4.1.4 RC1/AN5/C12IN1-/PH1 The RC1 is configurable to function as one of the following: • • • • a general purpose I/O an analog input for the A/D Converter an analog input to Comparators 1 and 2 a digital output from the Two-Phase PWM RC0/AN4/C2IN+ The RC0 is configurable to function as one of the following: • a general purpose I/O • an analog input for the A/D Converter • the non-inverting input to Comparator 2 4.4.1.2 FIGURE 4-11: PH1EN PH1 Data Bus D RC6/AN8/OP1- The RC6/AN8/OP1- pin is configurable to function as one of the following: • a general purpose I/O • an analog input for the A/D • the inverting input for Op Amp 1 4.4.1.3 BLOCK DIAGRAM OF RC1 WR PORTC CK VDD Q Q 1 0 D WR TRISC CK I/O Pin Q Q VSS ANS5 RC7/AN9/OP1+ The RC7/AN9/OP1+ pin is configurable to function as one of the following: • a general purpose I/O • an analog input for the A/D • the non-inverting input for Op Amp 1 RD TRISC Q D EN RD PORTC To Comparators FIGURE 4-10: BLOCK DIAGRAM OF RC0, RC6 AND RC7 To A/D Converter Data Bus D WR PORTC CK VDD Q Q I/O Pin D WR TRISC CK Q Q VSS ANS4 (RC0) ANS8 (RC6) ANS9 (RC7) RD TRISC Q D EN RD PORTC To Comparators (RC0) To A/D Converter To Op Amp1 (RC6, RC7) DS41249B-page 46 Preliminary © 2005 Microchip Technology Inc. PIC16F785 4.4.1.5 4.4.1.7 RC2/AN6/C12IN2-/OP2 RC4/C2OUT/PH2 The RC2 is configurable to function as one of the following: The RC4 is configurable to function as one of the following: • • • • • a general purpose I/O • a digital output from Comparator 2 • a digital output from the Two-Phase PWM a general purpose I/O an analog input for the A/D Converter an analog input to Comparators 1 and 2 an analog output from Op Amp 2 FIGURE 4-13: 4.4.1.6 The RC3 is configurable to function as one of the following: • • • • BLOCK DIAGRAM OF RC4 RC3/AN7/C12IN3-/OP1 a general purpose I/O an analog input for the A/D Converter an analog input to Comparators 1 and 2 an analog output for Op Amp 1 FIGURE 4-12: C2OE PH2EN PH2 1 C2OUT 0 Data Bus BLOCK DIAGRAM OF RC2 AND RC3 D WR PORTC CK VDD Q Q 1 Op Amp out 0 OPAON Data Bus D D WR PORTC CK WR TRISC VDD Q WR TRISC CK Q VSS RD TRISC Q I/O Pin D CK I/O Pin Q Q D Q EN Q VSS ANS6 (RC2) ANS7 (RC3) RD TRISC Q RD PORTC D EN RD PORTC To Comparators To A/D Converter © 2005 Microchip Technology Inc. Preliminary DS41249B-page 47 PIC16F785 4.4.1.8 RC5/CCP1 FIGURE 4-14: The RC5 is configurable to function as one of the following: CCP1CON<1> CCP1CON<3> • a general purpose I/O • a digital input for the capture/compare • a digital output for the CCP CCP1CON<2> BLOCK DIAGRAM OF RC5 CCP out Data Bus D WR PORTC VDD Q CK Q 1 0 D WR TRISC I/O Pin Q CK Q VSS RD TRISC Q D EN RD PORTC to CCP Capture Input TABLE 4-3: Address SUMMARY OF REGISTERS ASSOCIATED WITH PORTC Name 07h, 107h PORTC 15h CCP1CON Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 RC3 RC2 RC1 RC0 Value on: POR, BOR Value on all other Resets Bit 7 Bit 6 RC7 RC6 RC5 RC4 — — DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 xxxx xxxx uuuu uuuu 0000 0000 0000 0000 87h, 187h TRISC 91h ANSEL0 93h ANSEL1 — — — — ANS11 ANS10 ANS9 ANS8 ---- 1111 ---- 1111 111h PWMCON0 PRSEN PASEN BLANK2 BLANK1 SYNC1 SYNC0 PH2EN PH1EN 0000 0000 0000 0000 11Ch OPA1CON OPAON — — — — — — — 0--- ---- 0--- ---- 11Dh OPA2CON OPAON — — — — — — — 0--- ---- 0--- ---- Legend: x = unknown, u = unchanged, – = unimplemented locations read as ‘0’. Shaded cells are not used by PORTC. DS41249B-page 48 Preliminary © 2005 Microchip Technology Inc. PIC16F785 5.0 TIMER0 MODULE Counter mode is selected by setting the T0CS bit (OPTION_REG<5>). In this mode, the Timer0 module will increment either on every rising or falling edge of pin RA2/AN2/T0CKI/INT/C1OUT. The incrementing edge is determined by the source edge (T0SE) control bit (OPTION_REG<4>). Clearing the T0SE bit selects the rising edge. The Timer0 module timer/counter has the following features: • • • • • • 8-bit timer/counter Readable and writable 8-bit software programmable prescaler Internal or external clock select Interrupt on overflow from FFh to 00h Edge select for external clock Note 1: Counter mode has specific external clock requirements. Additional information on these requirements is available in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). Figure 5-1 is a block diagram of the Timer0 module and the prescaler shared with the WDT. Note: 2: The ANSEL0 (91h) register must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. Additional information on the Timer0 module is available in the “PICmicro® MidRange MCU Family Reference Manual” (DS33023). 5.2 5.1 Timer0 Operation A Timer0 interrupt is generated when the TMR0 register timer/counter overflows from FFh to 00h. This overflow sets the T0IF bit (INTCON<2>). The interrupt can be masked by clearing the T0IE bit (INTCON<5>). The T0IF bit must be cleared in software by the Timer0 module Interrupt Service Routine before re-enabling this interrupt. The Timer0 interrupt cannot wake the processor from Sleep since the timer is shut-off during Sleep. Timer mode is selected by clearing the T0CS bit (OPTION_REG<5>). In Timer mode, the Timer0 module will increment every instruction cycle (without prescaler). If TMR0 is written, 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. FIGURE 5-1: Timer0 Interrupt BLOCK DIAGRAM OF THE TIMER0/WDT PRESCALER CLKOUT (= FOSC/4) Data Bus 0 8 RA2/AN2/T0CKI/INT/C1OUT 1 SYNC 2 Cycles 1 TMR0 0 T0SE(1) T0CS(1) 0 8-bit Prescaler PSA Set Flag bit T0IF on Overflow (1) 1 WDTE 8 PSA(1) SWDTEN PS<0:2>(1) 16-bit Prescaler 31 kHz INTRC 1 WDT Time-out 0 16 Watchdog Timer PSA(1) WDTPS<3:0>(2) Note 1: T0SE, T0CS, PSA, PS<2:0> are bits in the OPTION_REG (see Register 2-2). 2: WDTPS<3:0> are bits in the WDTCON register (see Register 15-2). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 49 PIC16F785 5.3 EXAMPLE 5-1: Using Timer0 with an External Clock BCF STATUS,RP0 BCF STATUS,RP1 CLRWDT CLRF TMR0 When no prescaler is used, the external clock input is the same as the prescaler output. The synchronization of T0CKI, with the internal phase clocks, is accomplished by sampling the prescaler output on the Q2 and Q4 cycles of the internal phase clocks. Therefore, it is necessary for T0CKI to be high for at least 2TOSC (and a small RC delay of 20 ns) and low for at least 2TOSC (and a small RC delay of 20 ns). Refer to the electrical specification of the desired device. 5.4 BSF ;Bank 0 ; ;Clear WDT ;Clear TMR0 and ; prescaler ;Bank 1 STATUS,RP0 MOVLW b’00101111’ MOVWF OPTION_REG CLRWDT MOVLW MOVWF BCF Prescaler An 8-bit counter is available as a prescaler for the Timer0 module, or as a postscaler for the Watchdog Timer. For simplicity, this counter will be referred to as “prescaler” throughout this Data Sheet. The prescaler assignment is controlled in software by the control bit PSA (OPTION_REG<3>). Clearing the PSA bit will assign the prescaler to Timer0. Prescale values are selectable via the PS<2:0> bits (OPTION_REG<2:0>). ;Required if desired ; PS2:PS0 is ; 000 or 001 ; ;Set postscaler to ; desired WDT rate ;Bank 0 b’00101xxx’ OPTION_REG STATUS,RP0 To change prescaler from the WDT to the TMR0 module, use the sequence shown in Example 5-2. This precaution must be taken even if the WDT is disabled. EXAMPLE 5-2: The prescaler is not readable or writable. When assigned to the Timer0 module, all instructions writing to the TMR0 register (e.g., CLRF 1, MOVWF 1, BSF 1,x....etc.) will clear the prescaler. When assigned to WDT, a CLRWDT instruction will clear the prescaler along with the Watchdog Timer. 5.4.1 CHANGING PRESCALER (TIMER0→WDT) CHANGING PRESCALER (WDT→TIMER0) CLRWDT SWITCHING PRESCALER ASSIGNMENT BSF BCF STATUS,RP0 STATUS,RP1 MOVLW b’xxxx0xxx’ MOVWF BCF OPTION_REG STATUS,RP0 ;Clear WDT and ; prescaler ;Bank 1 ; ;Select TMR0, ; prescale, and ; clock source ; ;Bank 0 The prescaler assignment is fully under software control (i.e., it can be changed “on the fly” during program execution). To avoid an unintended device Reset, the following instruction sequence (Example 5-1 and Example 5-2) must be executed when changing the prescaler assignment between Timer0 and WDT. TABLE 5-1: Addr REGISTERS ASSOCIATED WITH TIMER0 Name 01h, 101h TMR0 0Bh, 8Bh INTCON 81h, 181h Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Timer0 Module Register Value on: POR, BOR Value on all other Resets xxxx xxxx uuuu uuuu GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 OPTION_REG RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111 91h ANSEL0 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 85h, 185h TRISA — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111 Legend: – = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Timer0 module. DS41249B-page 50 Preliminary © 2005 Microchip Technology Inc. PIC16F785 6.0 TIMER1 MODULE WITH GATE CONTROL The Timer1 Control register (T1CON), shown in Register 6-1, is used to enable/disable Timer1 and select the various features of the Timer1 module. The Timer1 module is the 16-bit counter of the PIC16F785. Figure 6-1 shows the basic block diagram of the Timer1 module. Timer1 has the following features: Note: Additional information on timer modules is available in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). • • • • • • • 16-bit timer/counter (TMR1H:TMR1L) Readable and writable Internal or external clock selection Synchronous or asynchronous operation Interrupt on overflow from FFFFh to 0000h Wake-up upon overflow (Asynchronous mode) Optional external enable input: - Selectable gate source; T1G or C2 output (T1GSS) - Selectable gate polarity (T1GINV) • Optional LP oscillator FIGURE 6-1: TIMER1 ON THE PIC16F785 BLOCK DIAGRAM TMR1ON TMR1GE T1GINV TMR1ON TMR1GE Set flag bit TMR1IF on Overflow To C2 Comparator Module TMR1 Clock TMR1(1) TMR1H RA5/T1CKI/OSC1/CLKIN 0 TMR1L Synchronized clock input 1 Oscillator T1SYNC * 1 RA4/AN3/T1G/OSC2/CLKOUT T1OSCEN INTOSC Without CLKOUT FOSC/4 Internal Clock Prescaler 1, 2, 4, 8 Synchronize det 0 2 T1CKPS<1:0> Sleep input TMR1CS 1 LP Sleep SYNCC2OUT(2) * Note 1: 2: ST Buffer is low power type when using LP OSC, or high-speed type when using T1CKI. 0 T1GSS Timer1 increments on the rising edge. SYNCC2OUT is the synchronized output from Comparator 2 (See Figure 9-2 on 66). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 51 PIC16F785 6.1 Timer1 Modes of Operation The interrupt is cleared by clearing the TMR1IF in the Interrupt Service Routine. Timer1 can operate in one of three modes: Note: • 16-bit Timer with prescaler • 16-bit Synchronous counter • 16-bit Asynchronous counter In Timer mode, Timer1 is incremented on every instruction cycle. In Counter mode, Timer1 is incremented on the rising edge of the external clock input T1CKI. In addition, the Counter mode clock can be synchronized to the microcontroller system clock or run asynchronously. In Counter and Timer modules, the counter/timer clock can be gated by the Timer1 gate, which can be selected as either the T1G pin or Comparator 2 output. If an external clock oscillator is needed (and the microcontroller is using the LP oscillator or INTOSC without CLKOUT), Timer1 can use the LP oscillator as a clock source. Note: In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge after any one or more of the following conditions. •Timer1 enabled after POR Reset •Write to TMR1H or TMR1L •Timer1 is disabled (TMR1ON = 0) when T1CKI is high then Timer1 is enabled (TMR1ON = 1) when T1CKI is low. Timer1 Interrupt The Timer1 register pair (TMR1H:TMR1L) increments to FFFFh and rolls over to 0000h. When Timer1 rolls over, the Timer1 interrupt flag bit (PIR1<0>) is set. To enable the interrupt on rollover, you must set these bits: Timer1 Prescaler Timer1 has four prescaler options allowing 1, 2, 4 or 8 divisions of the clock input. The T1CKPS bits (T1CON<5:4>) control the prescale counter. The prescale counter is not directly readable or writable; however, the prescaler counter is cleared upon a write to TMR1H or TMR1L. 6.4 Timer1 Gate Timer1 gate source is software configurable to be T1G pin or the output of Comparator 2. This allows the device to directly time external events using T1G or analog events using Comparator 2. See CM2CON1 (Register 9-3) for selecting the Timer1 gate source. This feature can simplify the software for a Delta-Sigma A/D Converter and many other applications. For more information on Delta-Sigma A/D Converters, see the Microchip web site (www.microchip.com). Note: See Figure 6-2. 6.2 6.3 The TMR1H:TMR1L register pair and the TMR1IF bit should be cleared before enabling interrupts. TMR1GE bit (T1CON<6>) must be set to use either T1G or C2OUT as the Timer1 gate source. See Register 9-3 for more information on selecting the Timer1 gate source. Timer1 gate can be inverted using the T1GINV bit (T1CON<7>), whether it originates from the T1G pin or Comparator 2 output. This configures Timer1 to measure either the active high or active low time between events. • Timer1 Interrupt Enable bit (PIE1<0>) • PEIE bit (INTCON<6>) • GIE bit (INTCON<7>) FIGURE 6-2: TIMER1 INCREMENTING EDGE T1CKI = 1 when TMR1 Enabled T1CKI = 0 when TMR1 Enabled Note 1: 2: Arrows indicate counter increments. See note box in Section 6.1. DS41249B-page 52 Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 6-1: T1CON – TIMER1 CONTROL REGISTER (ADDRESS: 10h) R/W-0 R/W-0 R/W-0 T1GINV(1) TMR1GE(2) T1CKPS1 R/W-0 R/W-0 T1CKPS0 T1OSCEN R/W-0 R/W-0 R/W-0 T1SYNC TMR1CS TMR1ON bit 7 bit 0 bit 7 T1GINV: Timer1 Gate Invert bit (1) 1 = Timer1 gate is high true (see bit 6) 0 = Timer1 gate is low true (see bit 6) bit 6 TMR1GE: Timer1 Gate Enable bit (2) If TMR1ON = 0: This bit is ignored If TMR1ON = 1: 1 = Timer1 is on if Timer1 gate is true (see bit 7) 0 = Timer1 is on independent of Timer1 gate bit 5-4 T1CKPS<1:0>: Timer1 Input Clock Prescale Select bits 11 = 1:8 Prescale Value 10 = 1:4 Prescale Value 01 = 1:2 Prescale Value 00 = 1:1 Prescale Value bit 3 T1OSCEN: LP Oscillator Enable Control bit If System Clock is INTOSC without CLKOUT or LP mode: 1 = LP oscillator is enabled for Timer1 clock 0 = LP oscillator is off Else: This bit is ignored bit 2 T1SYNC: Timer1 External Clock Input Synchronization Control bit TMR1CS = 1: 1 = Do not synchronize external clock input 0 = Synchronize external clock input TMR1CS = 0: This bit is ignored. Timer1 uses the internal clock. bit 1 TMR1CS: Timer1 Clock Source Select bit 1 = External clock from T1CKI pin (on the rising edge) 0 = Internal clock (FOSC/4) bit 0 TMR1ON: Timer1 On bit 1 = Enables Timer1 0 = Stops Timer1 Note 1: T1GINV bit inverts the Timer1 gate logic, regardless of source. 2: TMR1GE bit must be set to use either T1G pin or C2OUT, as selected by T1GSS bit (CM2CON1<1>), as a Timer1 gate source. Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 53 PIC16F785 6.5 Timer1 Operation in Asynchronous Counter Mode 6.6 A crystal oscillator circuit is built-in between pins OSC1 (input) and OSC2 (amplifier output). It is enabled by setting control bit T1OSCEN (T1CON<3>). The oscillator is a low power oscillator rated for 32.768 kHz. It will continue to run during Sleep. It is primarily intended for a 32.768 kHz tuning fork crystal. If control bit T1SYNC (T1CON<2>) is set, the external clock input is not synchronized. The timer continues to increment asynchronous to the internal phase clocks. The timer will continue to run during Sleep and can generate an interrupt on overflow, which will wake-up the processor. However, special precautions in software are needed to read/write the timer (Section 6.5.1 “Reading and Writing Timer1 in Asynchronous Counter Mode”). Note: The Timer1 oscillator is shared with the system LP oscillator. Thus, Timer1 can use this mode only when the primary system clock is also the LP oscillator or is derived from the internal oscillator. As with the system LP oscillator, the user must provide a software time delay to ensure proper oscillator start-up. The ANSEL0 (91h) register must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. 6.5.1 Sleep mode will not disable the system clock when the system clock and Timer1 share the LP oscillator. TRISA<5> and TRISA<4> bits are set when the Timer1 oscillator is enabled. RA5 and RA4 read as ‘0’ and TRISA<5> and TRISA<4> bits read as ‘1’. READING AND WRITING TIMER1 IN ASYNCHRONOUS COUNTER MODE Note: Reading TMR1H or TMR1L while the timer is running from an external asynchronous clock will ensure a valid read (taken care of in hardware). However, the user should keep in mind that reading the 16-bit timer in two 8-bit values itself, poses certain problems, since the timer may overflow between the reads. 6.7 The oscillator requires a start-up and stabilization time before use. Thus, T1OSCEN should be set and a suitable delay observed prior to enabling Timer1. Timer1 Operation During Sleep Timer1 can only operate during Sleep when setup in Asynchronous Counter mode. In this mode, an external crystal or clock source can be used to increment the counter. To setup the timer to wake the device: For writes, it is recommended that the user simply stop the timer and write the desired values. A write contention may occur by writing to the timer registers, while the register is incrementing. This may produce an unpredictable value in the timer register. • Timer1 must be on (T1CON<0>) • TMR1IE bit (PIE1<0>) must be set • PEIE bit (INTCON<6>) must be set Reading the 16-bit value requires some care. Examples in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023) show how to read and write Timer1 when it is running in Asynchronous mode. TABLE 6-1: Timer1 Oscillator The device will wake-up on an overflow. If the GIE bit (INTCON<7>) is set, the device will wake-up and jump to the Interrupt Service Routine (0004h) on an overflow. If the GIE bit is clear, execution will continue with the next instruction. REGISTERS ASSOCIATED WITH TIMER1 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets 0Bh, 8Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu 0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu 10h T1CON 11Bh CM2CON1 MC1OUT MC2OUT — — — 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE 91h ANSEL0 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 Addr Legend: T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu — T1GSS C2SYNC 00-- --10 00-- --10 OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 ANS1 ANS0 1111 1111 1111 1111 x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the Timer1 module. DS41249B-page 54 Preliminary © 2005 Microchip Technology Inc. PIC16F785 7.0 TIMER2 MODULE 7.1 The Timer2 module timer is an 8-bit timer with the following features: • • • • • 8-bit timer (TMR2 register) 8-bit period register (PR2) Readable and writable (both registers) Software programmable prescaler (1:1, 1:4, 1:16) Software programmable postscaler (1:1 to 1:16 by 1’s) • Interrupt on TMR2 match with PR2 Timer2 has a control register shown in Register 7-1. TMR2 can be shut-off by clearing control bit TMR2ON (T2CON<2>) to minimize power consumption. Figure 7-1 is a simplified block diagram of the Timer2 module. The prescaler and postscaler selection of Timer2 are controlled by this register. REGISTER 7-1: Timer2 Operation Timer2 can be used as the PWM time base for the PWM mode of the CCP module. The TMR2 register is readable and writable, and is cleared on any device Reset. The input clock (FOSC/4) has a prescale option of 1:1, 1:4 or 1:16, selected by control bits T2CKPS<1:0> (T2CON<1:0>). The match output of TMR2 goes through a 4-bit postscaler (which gives a 1:1 to 1:16 scaling inclusive) to generate a TMR2 interrupt (latched in flag bit TMR2IF, (PIR1<1>)). The prescaler and postscaler counters are cleared when any of the following occurs: • 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. T2CON – TIMER2 CONTROL REGISTER (ADDRESS: 12h) U-0 R/W-0 R/W-0 R/W-0 R/W-0 — TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 R/W-0 R/W-0 TMR2ON T2CKPS1 R/W-0 T2CKPS0 bit 7 bit 0 bit 7 Unimplemented: Read as ‘0’ bit 6-3 TOUTPS<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 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 55 PIC16F785 7.2 Timer2 Interrupt The Timer2 module has an 8-bit period register, PR2. Timer2 increments from 00h until it matches PR2 and then resets to 00h on the next increment cycle. PR2 is a readable and writable register. The PR2 register is initialized to FFh upon Reset. FIGURE 7-1: TIMER2 BLOCK DIAGRAM Sets Flag bit TMR2IF TMR2 Output Prescaler 1:1, 1:4, 1:16 FOSC/4 2 Reset TMR2 Postscaler 1:1 to 1:16 Comparator EQ T2CKPS<1:0> 4 PR2 TOUTPS<3:0> TABLE 7-1: Addr 0Bh, 8Bh Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 0000 0000 0000 0000 -000 0000 -000 0000 0000 0000 0000 0000 1111 1111 1111 1111 0Ch PIR1 11h TMR2 12h T2CON 8Ch PIE1 92h PR2 Legend: REGISTERS ASSOCIATED WITH TIMER2 Holding Register for the 8-bit TMR2 Register — EEIE TOUTPS3 TOUTPS2 ADIE CCP1IE TOUTPS1 TOUTPS0 C2IE C1IE TMR2ON T2CKPS1 T2CKPS0 Timer2 Module Period register OSFIE TMR2IE TMR1IE x = unknown, u = unchanged, – = unimplemented, read as ‘0’. Shaded cells are not used by the Timer2 module. DS41249B-page 56 Preliminary © 2005 Microchip Technology Inc. PIC16F785 8.0 CAPTURE/COMPARE/PWM (CCP) MODULE TABLE 8-1: The Capture/Compare/PWM (CCP) module contains a 16-bit register which can operate as a: • 16-bit Capture register • 16-bit Compare register • PWM Master/Slave Duty Cycle register CCP MODE – TIMER RESOURCES REQUIRED CCP Mode Timer Resource Capture Timer1 Compare Timer1 PWM Timer2 Capture/Compare/PWM Register 1 (CCPR1) is comprised of two 8-bit registers: CCPR1L (low byte) and CCPR1H (high byte). The CCP1CON register controls the operation of CCP. The special event trigger is generated by a compare match and will clear both TMR1H and TMR1L registers. REGISTER 8-1: CCP1CON – CCP OPERATION REGISTER (ADDRESS: 15h) U-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — — DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 bit 7 bit 7-6 bit 5-4 bit 3-0 bit 0 Unimplemented: Read as ‘0’. DC1B<1:0>: PWM Duty Cycle Least Significant bits Capture mode: Unused Compare mode: Unused PWM mode: These bits are the two LSbs of the PWM duty cycle. The eight MSbs are found in CCPR1L. CCP1M<3:0>: CCP Mode Select bits 0000 = Capture/Compare/PWM off (resets CCP module) 0001 = Unused (reserved) 0010 = Compare mode, toggle output on match (CCP1IF bit is set) 0011 = Unused (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, set output on match (CCP1IF bit is set) 1001 = Compare mode, clear output on match (CCP1IF bit is set) 1010 = Compare mode, generate software interrupt on match (CCP1IF bit is set, CCP1 pin is unaffected) 1011 = Compare mode, trigger special event (CCP1IF bit is set; TMR1 is reset, and A/D conversion is started if the A/D module is enabled. CCP1 pin is unaffected.) 110x = PWM mode: CCP1 output is high true. 111x = PWM mode: CCP1 output is low true. Legend: R = Readable bit - n = Value at POR © 2005 Microchip Technology Inc. W = Writable bit ‘1’ = Bit is set Preliminary U = Unimplemented bit, read as ‘0’ ‘0’ = Bit is cleared x = Bit is unknown DS41249B-page 57 PIC16F785 8.1 8.1.4 Capture Mode In Capture mode, CCPR1H:CCPR1L captures the 16-bit value of the TMR1 register when an event occurs on pin RC5/CCP1. An event is defined as one of the following and is configured by CCP1CON<3:0>: • • • • Every falling edge Every rising edge Every 4th rising edge Every 16th rising edge When a capture is made, the interrupt request flag bit CCP1IF (PIR1<5>) is set. The interrupt flag must be cleared in software. If another capture occurs before the value in register CCPR1 is read, the old captured value is overwritten by the new captured value. 8.1.1 CCP1 PIN CONFIGURATION In Capture mode, the RC5/CCP1 pin should be configured as an input by setting the TRISC<5> bit. Note: If the RC5/CCP1 pin is configured as an output, a write to the port can cause a capture condition. FIGURE 8-1: Prescaler ÷ 1, 4, 16 CCPR1H and Edge Detect CCPR1L EXAMPLE 8-1: CLRF MOVLW MOVWF CHANGING BETWEEN CAPTURE PRESCALERS CCP1CON ;Turn CCP module off NEW_CAPT_PS ;Load the W reg with ; the new prescaler ; move value and CCP ON CCP1CON ;Load CCP1CON with this ; value Compare Mode • Driven high • Driven low • Remains unchanged The action on the pin is based on the value of control bits CCP1M<3:0> (CCP1CON<3:0>). At the same time, interrupt flag bit CCP1IF (PIR1<5>) is set. Capture Enable TMR1H 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 nonzero prescaler. Example 8-1 shows the recommended method for switching between capture prescalers. This example also clears the prescaler counter and will not generate the “false” interrupt. In Compare mode, the 16-bit CCPR1 register value is constantly compared against the TMR1 register pair value. When a match occurs, the RC5/CCP1 pin is: Set Flag bit CCP1IF (PIR1<5>) RC5/CCP1 pin There are four prescaler settings specified by bits CCP1M<3:0> (CCP1CON<3:0>). Whenever the CCP module is turned off, or the CCP module is not in Capture mode, the prescaler counter is cleared. Any Reset will clear the prescaler counter. 8.2 CAPTURE MODE OPERATION BLOCK DIAGRAM CCP PRESCALER TMR1L CCP1CON<3:0> FIGURE 8-2: Q’s 8.1.2 COMPARE MODE OPERATION BLOCK DIAGRAM TIMER1 MODE SELECTION CCP1CON<3:0> Mode Select Timer1 must be running in Timer mode or Synchronized Counter mode for the CCP module to use the capture feature. In Asynchronous Counter mode, the capture operation may not work. 8.1.3 Set Flag bit CCP1IF (PIR1<5>) 4 CCPR1H CCPR1L RC5/CCP1 Pin SOFTWARE INTERRUPT Q When the Capture mode is changed, a false capture interrupt may be generated. The user should keep bit CCP1IE (PIE1<5>) clear to avoid false interrupts and should clear the flag bit CCP1IF (PIR1<5>) following any such change in Operating mode. S R Output Logic Match Comparator TMR1H TRISC<5> Output Enable TMR1L Special Event Trigger Special Event Trigger will: • clear TMR1H and TMR1L registers • NOT set interrupt flag bit TMR1F (PIR1<0>) • set the GO/DONE bit (ADCON0<1>) DS41249B-page 58 Preliminary © 2005 Microchip Technology Inc. PIC16F785 8.2.1 CCP1 PIN CONFIGURATION 8.2.4 The user must configure the RC5/CCP1 pin as an output by clearing the TRISC<5> bit. Note: In this mode (CCP1M<3:0> = 1011), an internal hardware trigger is generated, which may be used to initiate an action. See Register 8-1. Clearing the CCP1CON register will force the RC5/CCP1 compare output latch to the default low level. This is not the PORTC I/O data latch. 8.2.2 The special event trigger output of the CCP occurs immediately upon a match between the TMR1H, TMR1L register pair and CCPR1H, CCPR1L register pair. The TMR1H, TMR1L register pair is not reset until the next rising edge of the TMR1 clock. This allows the CCPR1H, CCPR1L register pair to effectively provide a 16-bit programmable period register for Timer1. The special event trigger output also starts an A/D conversion provided that the A/D module is enabled. TIMER1 MODE SELECTION Timer1 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. 8.2.3 Note 1: The special event trigger from the CCP module will not set interrupt flag bit TMR1IF (PIR1<0>). SOFTWARE INTERRUPT MODE When Generate Software Interrupt mode is chosen (CCP1M<3:0> = 1010), the RC5/CCP1 pin is not affected. The CCP1IF (PIR1<5>) bit is set, causing a CCP interrupt (if enabled). See Register 8-1. TABLE 8-2: SPECIAL EVENT TRIGGER 2: Removing the match condition by changing the contents of the CCPR1H and CCPR1L register pair between the clock edge that generates the special event trigger and the clock edge that generates the TMR1 Reset, will preclude the Reset from occurring. REGISTERS ASSOCIATED WITH CAPTURE, COMPARE, AND TIMER1 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets 0Bh 8Bh INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu 0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu 10h T1CON Addr T1GINV TMR1GE T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON 0000 0000 uuuu uuuu — — — — T1GSS C2SYNC 11Bh CM2CON1 MC1OUT MC2OUT 00-- --10 00-- --10 13h CCPR1L Capture/Compare/PWM Register 1 Low Byte xxxx xxxx uuuu uuuu 14h CCPR1H Capture/Compare/PWM Register 1 High Byte xxxx xxxx uuuu uuuu 15h CCP1CON 87h, 187h TRISC 8Ch PIE1 Legend: — — DC1B1 DC1B0 CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000 TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 – = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the Capture, Compare or Timer1 module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 59 PIC16F785 8.3 8.3.1 CCP PWM Mode In Pulse Width Modulation (PWM) mode, the CCP module produces up to a 10-bit resolution PWM output on the RC5/CCP1 pin. Since the RC5/CCP1 pin is multiplexed with the PORTC data latch, the TRISC<5> must be cleared to make the RC5/CCP1 pin an output. Note: The PWM period is specified by writing to the PR2 register. The PWM period can be calculated using the formula of Equation 8-1. EQUATION 8-1: Clearing the CCP1CON register will force the PWM output latch to the default inactive levels. This is not the PORTC I/O data latch. Figure 8-3 shows a simplified block diagram of PWM operation. For a step by step procedure on how to set up the CCP module for PWM operation, see Section 8.3.5 “Setup for PWM Operation”. FIGURE 8-3: SIMPLIFIED PWM BLOCK DIAGRAM CCP1CON<5:4> PWM PERIOD PWM period = [ ( PR2 ) + 1 ] • 4 • T OSC • (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 RC5/CCP1 pin is set. (exception: if PWM duty cycle = 0%, the pin will not be set) • The PWM duty cycle is latched from CCPR1L into CCPR1H Note: Duty Cycle Registers PWM PERIOD CCPR1L CCPR1H (Slave) The Timer2 postscaler (see Section 7.1 “Timer2 Operation”) 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. RC5/CCP1 Comparator TMR2 (1) R Q S TRISC<5> Comparator Clear Timer2, toggle PWM pin and latch duty cycle PR2 Note 1: The 8-bit timer TMR2 register is concatenated with the 2-bit internal Q clock, or 2 bits of the prescaler, to create the 10-bit time base. The PWM output (Figure 8-4) 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 8-4: CCP PWM OUTPUT Period Duty Cycle TMR2 = PR2 TMR2 = Duty Cycle TMR2 = 0 DS41249B-page 60 Preliminary © 2005 Microchip Technology Inc. PIC16F785 8.3.2 PWM DUTY CYCLE The PWM duty cycle is specified by writing to the CCPR1L register and to the DC1B<1:0> (CCP1CON<5:4>) bits. Up to 10 bits of resolution is available. The CCPR1L contains the eight MSbs and the DC1B<1:0> contains the two LSbs. CCPR1L and DC1B<1:0> can be written to at any time. In PWM mode, CCPR1H is a read-only register. This 10-bit value is represented by CCPR1L (CCP1CON<5:4>). Equation 8-2 is used to calculate the PWM duty cycle in time. EQUATION 8-2: PWM DUTY CYCLE CCPR1L and DC1B<1:0> can be written to at any time, but the duty cycle value is not latched into CCPR1H until after 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. Because of the buffering, the module waits until the 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). When the CCPR1H and 2-bit latch match TMR2, concatenated with an internal 2-bit Q clock or 2 bits of the TMR2 prescaler, the RC5/CCP1 pin is cleared. PWM duty cycle = ( CCPR1L:CCP1CON<5:4> ) • T OSC • (TMR2 prescale value) The maximum PWM resolution is a function of PR2 as shown by Equation 8-3. EQUATION 8-3: PWM RESOLUTION [ 4 ( PR2 + 1 ) ] bits Resolution = log ----------------------------------------log ( 2 ) Note: TABLE 8-3: If the PWM duty cycle value is longer than the PWM period, the assigned PWM pin(s) will remain unchanged. EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz) PWM Frequency Timer Prescale (1, 4, 16) PR2 Value Maximum Resolution (bits) 1.22 kHz(1) 4.88 kHz(1) 19.53 kHz 78.12 kHz 156.3 kHz 208.3 kHz 16 4 1 1 1 1 0xFF 0xFF 0xFF 0x3F 0x1F 0x17 10 10 10 8 7 6.6 Note 1: Changing duty cycle will cause a glitch. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 61 PIC16F785 8.3.3 OPERATION IN SLEEP MODE 8.3.5 In Sleep mode, all clock sources are disabled. Timer2 will not increment and the state of the module will not change. If the RC5/CCP1 pin is driving a value, it will continue to drive that value. When the device wakes up, it will continue from this state. 8.3.3.1 The following steps should be taken when configuring the CCP module for PWM operation: 1. Configure the PWM pin (RC5/CCP1) as an input by setting the TRISC<5> bit. Set the PWM period by loading the PR2 register. Configure the CCP module for the PWM mode by loading the CCP1CON register with the appropriate values. Set the PWM duty cycle by loading the CCPR1L register and CCP1CON<5:4> bits. 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>). Enable PWM output after a new PWM cycle has started: • Wait until TMR2 overflows (TMR2IF bit is set). • Enable the RC5/CCP1 pin output by clearing the TRISC<5> bit. 2. 3. OPERATION WITH FAIL-SAFE CLOCK MONITOR If the Fail-Safe Clock Monitor is enabled, a clock failure will force the CCP to be clocked from the internal oscillator clock source, which may have a different clock frequency than the primary clock. 4. 5. See Section 3.0 “Clock Sources” for additional details. 8.3.4 EFFECTS OF RESET Any Reset will force all ports to Input mode and the CCP registers to their Reset states. 6. TABLE 8-4: REGISTERS ASSOCIATED WITH CCP AND TIMER2 Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets INTCON GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF Addr 0Bh, 8Bh SETUP FOR PWM OPERATION 0Ch PIR1 11h TMR2 12h T2CON 13h CCPR1L Capture/Compare/PWM Register 1 Low Byte 14h CCPR1H Capture/Compare/PWM Register 1 High Byte xxxx xxxx uuuu uuuu 15h CCP1CON CCP1M0 0000 0000 0000 0000 87h TRISC 8Ch PIE1 92h PR2 Legend: Timer2 Module Register — TOUTPS3 TOUTPS2 — — TRISC7 EEIE TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 0000 0000 0000 0000 -000 0000 -000 0000 xxxx xxxx uuuu uuuu DC1B1 DC1B0 CCP1M3 CCP1M2 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 --11 1111 --11 1111 ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 1111 1111 1111 1111 Timer2 Module Period Register CCP1M1 0000 0000 0000 0000 – = Unimplemented locations, read as ‘0’, u = unchanged, x = unknown. Shaded cells are not used by the CCP or Timer2 modules. DS41249B-page 62 Preliminary © 2005 Microchip Technology Inc. PIC16F785 9.0 COMPARATOR MODULE The Comparator module has two separate voltage comparators: Comparator 1 (C1) and Comparator 2 (C2). The polarity of the comparator output can be inverted by setting the C1POL bit (CM1CON0<4>). Clearing C1POL results in a non-inverted output. A complete table showing the output state versus input conditions and the polarity bit is shown in Table 9-1. Each comparator offers the following list of features: • • • • • • • • • • Control and Configuration register Comparator output available externally Programmable output polarity Interrupt-on-change flags Wake-up from Sleep Configurable as feedback input to the PWM Programmable four input multiplexer Programmable two input reference selections Programmable speed/power Output synchronization to Timer1 clock input (Comparator C2 only) 9.1 TABLE 9-1: Input Condition C1POL C1OUT C1VN > C1VP 0 0 C1VN < C1VP 0 1 C1VN > C1VP 1 1 C1VN < C1VP 1 0 Note 1: The internal output of the comparator is latched at the end of each instruction cycle. External outputs are not latched. Control Registers Both comparators have separate control and Configuration registers: CM1CON0 for C1 and CM2CON0 for C2. In addition, Comparator C2 has a second control register, CM2CON1, for synchronization control and simultaneous reading of both comparator outputs. 9.1.1 C1 OUTPUT STATE VERSUS INPUT CONDITIONS COMPARATOR C1 CONTROL REGISTER 2: The C1 interrupt will operate correctly with C1OE set or cleared. 3: To output C1 on RA2/AN2/T0CKI/INT/ C1OUT:(C1OE = 1) and (C1ON = 1) and (TRISA<2> = 0). C1SP (CM1CON0<3>) configures the speed of the comparator. When C1SP is set, the comparator operates at its normal speed. Clearing C1SP operates the comparator in a slower, low-power mode. The CM1CON0 register (shown in Register 9-1) contains the control and Status bits for the following: • • • • • Comparator enable Comparator input selection Comparator reference selection Output mode Comparator speed Setting C1ON (CM1CON0<7>) enables Comparator C1 for operation. Bits C1CH<1:0> (CM1CON0<1:0>) select the comparator input from the four analog pins AN<7:5,1>. Note: To use AN<7:5,1> as analog inputs the appropriate bits must be programmed to ‘1’ in the ANSEL0 register. Setting C1R (CM1CON0<2>) selects the C1VREF output of the comparator voltage reference module as the reference voltage for the comparator. Clearing C1R selects the C1IN+ input on the RA0/AN0/C1IN+/ ICSPDAT pin. The output of the comparator is available internally via the C1OUT flag (CM1CON0<6>). To make the output available for an external connection, the C1OE bit (CM1CON0<5>) must be set. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 63 PIC16F785 FIGURE 9-1: COMPARATOR C1 SIMPLIFIED BLOCK DIAGRAM C1CH<1:0> C1POL 2 D RA1/AN1/C12IN0-/VREF/ICSPCLK RC1/AN5/C12IN1-/PH1 Q1 0 RC2/AN6/C12IN2-/OP2 1 MUX 2 RC3/AN7/C12IN3-/OP1 3 Q EN To Data Bus RD_CM1CON0 Set C1IF D Q Q3*RD_CM1CON0 C1ON(1) C1R EN CL NRESET To PWM Logic C1OE C1SP C1VN RA0/AN0/C1IN+/ICSPDAT C1VREF 0 MUX 1 C1OUT C1VP C1 RA2/AN2/T0CKI/INT/C1OUT(2) C1POL Note 1: 2: DS41249B-page 64 When C1ON = 0, the C1 comparator will produce a ‘0’ output to the XOR Gate. Output shown for reference only. For more detail, see Figure 4-3. Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 9-1: CM1CON0 – COMPARATOR C1 CONTROL REGISTER 0 (ADDRESS: 119h) R/W-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 C1ON C1OUT C1OE C1POL C1SP C1R C1CH1 C1CH0 bit 7 bit 0 bit 7 C1ON: Comparator C1 Enable bit 1 = C1 Comparator is enabled 0 = C1 Comparator is disabled bit 6 C1OUT: Comparator C1 Output bit If C1POL = 1 (inverted polarity): C1OUT = 1, C1VP < C1VN C1OUT = 0, C1VP > C1VN If C1POL = 0 (non-inverted polarity): C1OUT = 1, C1VP > C1VN C1OUT = 0, C1VP < C1VN bit 5 C1OE: Comparator C1 Output Enable bit 1 = C1OUT is present on the RA2/AN2/T0CKI/INT/C1OUT pin(1) 0 = C1OUT is internal only bit 4 C1POL: Comparator C1 Output Polarity Select bit 1 = C1OUT logic is inverted 0 = C1OUT logic is not inverted bit 3 C1SP: Comparator C1 Speed Select bit 1 = C1 operates in normal speed mode 0 = C1 operates in low-power, slow speed mode bit 2 C1R: Comparator C1 Reference Select bit (non-inverting input) 1 = C1VP connects to C1VREF output 0 = C1VP connects to RA0/AN0/C1IN+/ICSPDAT bit 1-0 C1CH<1:0>: Comparator C1 Channel Select bits 00 = C1VN of C1 connects to RA1/AN1/C12IN0-/VREF/ICSPCLK 01 = C1VN of C1 connects to RC1/AN5/C12IN1-/PH1 10 = C1VN of C1 connects to RC2/AN6/C12IN2-/OP2 11 = C1VN of C1 connects to RC3/AN7/C12IN3-/OP1 Note 1: C1OUT will only drive RA2/AN2/T0CKI/INT/C1OUT if: (C1OE = 1) and (C1ON = 1) and (TRISA<2> = 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 65 PIC16F785 9.1.2 COMPARATOR C2 CONTROL REGISTERS The comparator output, C2OUT, can be inverted by setting the C2POL bit (CM2CON0<4>). Clearing C2POL results in a non-inverted output. The CM2CON0 register is a functional copy of the CM1CON0 register described in Section 9.1.1 “Comparator C1 Control Register”. A second control register, CM2CON1, is also present for control of an additional synchronizing feature, as well as mirrors of both comparator outputs. 9.1.2.1 A complete table showing the output state versus input conditions and the polarity bit is shown in Table 9-2. TABLE 9-2: Control Register CM2CON0 C2 OUTPUT STATE VERSUS INPUT CONDITIONS Input Condition C2POL C2OUT The CM2CON0 register, shown in Register 9-2, contains the control and Status bits for Comparator C2. C2VN > C2VP 0 0 C2VN < C2VP 0 1 Setting C2ON (CM2CON0<7>) enables Comparator C2 for operation. C2VN > C2VP 1 1 C2VN < C2VP 1 0 Bits C2CH<1:0> (CM2CON0<1:0>) select the comparator input from the four analog pins, AN<7:5,1>. Note: To use AN<7:5,1> as analog inputs, the appropriate bits must be programmed to 1 in the ANSEL0 register. Note 1: The internal output of the comparator is latched at the end of each instruction cycle. External outputs are not latched. C2R (CM2CON0<2>) selects the reference to be used with the comparator. Setting C2R (CM2CON0<2>) selects the C2VREF output of the comparator voltage reference module as the reference voltage for the comparator. Clearing C2R selects the C2IN+ input on the RC0/AN4/C2IN+ pin. 2: The C2 interrupt will operate correctly with C2OE set or cleared. An external output is not required for the C2 interrupt. 3: For C2 output on RC4/C2OUT/PH2: (C2OE = 1) and (C2ON = 1) and (TRISA<4> = 0). The output of the comparator is available internally via the C2OUT bit (CM2CON0<6>). To make the output available for an external connection, the C2OE bit (CM2CON0<5>) must be set. FIGURE 9-2: C2SP (CM2CON0<3>) configures the speed of the comparator. When C2SP is set, the comparator operates at its normal speed. Clearing C2SP operates the comparator in low-power mode. COMPARATOR C2 SIMPLIFIED BLOCK DIAGRAM C2POL D Q1 EN RD_CM2CON0 2 C2CH<1:0> Set C2IF D Q3*RD_CM2CON0 RA1/AN1/C12IN0-/VREF/ICSPCLK C2ON(1) 0 RC1/AN5/C12IN1-/PH1 RC2/AN6/C12IN2-/OP2 1 MUX 2 RC3/AN7/C12IN3-/OP1 3 C2R C2SP C2VREF Note DS41249B-page 66 1: 2: 3: 0 MUX 1 Q EN CL NRESET C2VN C2VP To PWM Logic C2OUT C2 C2SYNC C2POL D RC0/AN4/C2IN+ To Data Bus Q Q 0 MUX 1 From TMR1 Clock C20E RC4/C2OUT/PH2(3) SYNCC2OUT(2) When C2ON = 0, the C2 comparator will produce a ‘0’ output to the XOR Gate. Timer1 gate control (see Figure 6-1). Output shown for reference only. For more detail, see Figure 4-13. Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 9-2: CM2CON0 – COMPARATOR C2 CONTROL REGISTER 0 (ADDRESS: 11AH) R/W-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 C2ON C2OUT C2OE C2POL C2SP C2R C2CH1 C2CH0 bit 7 bit 0 bit 7 C2ON: Comparator C2 Enable bit 1 = C2 Comparator is enabled 0 = C2 Comparator is disabled bit 6 C2OUT: Comparator C2 Output bit If C2POL = 1 (inverted polarity): C2OUT = 1, C2VP < C2VN C2OUT = 0, C2VP > C2VN If C2POL = 0 (non-inverted polarity): C2OUT = 1, C2VP > C2VN C2OUT = 0, C2VP < C2VN bit 5 C2OE: Comparator C2 Output Enable bit 1 = C2OUT is present on RC4/C2OUT/PH2(1) 0 = C2OUT is internal only bit 4 C2POL: Comparator C2 Output Polarity Select bit 1 = C2OUT logic is inverted 0 = C2OUT logic is not inverted bit 3 C2SP: Comparator C2 Speed Select bit 1 = C2 operates in normal speed mode 0 = C2 operates in low power, slow speed mode. bit 2 C2R: Comparator C2 Reference Select bits (non-inverting input) 1 = C2VP connects to C2VREF 0 = C2VP connects to RC0/AN4/C2IN+ bit 1-0 C2CH<1:0>: Comparator C2 Channel Select bits 00 = C2VN of C2 connects to RA1/AN1/C12IN0-/VREF/ICSPCLK 01 = C2VN of C2 connects to RC1/AN5/C12IN1-/PH1 10 = C2VN of C2 connects to RC2/AN6/C12IN2-/OP2 11 = C2VN of C2 connects to RC3/AN7/C12IN3-/OP1 Note 1: C2OUT will only drive RC4/C2OUT/PH2 if: (C2OE = 1) and (C2ON = 1) and (TRISC<4> = 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 67 PIC16F785 9.1.2.2 Control Register CM2CON1 Comparator C2 has one additional feature: its output can be synchronized to the Timer1 clock input. Setting C2SYNC (CM2CON1<0>) synchronizes the output of Comparator 2 to the falling edge of Timer1’s clock input (see Figure 9-2 and Register 9-3). The CM2CON1 register also contains mirror copies of both comparator outputs, MC1OUT and MC2OUT (CM2CON1<7:6>). The ability to read both outputs simultaneously from a single register eliminates the timing skew of reading separate registers. Note: REGISTER 9-3: Obtaining the status of C1OUT or C2OUT by reading CM2CON1 does not affect the comparator interrupt mismatch registers. CM2CON1 – COMPARATOR C2 CONTROL REGISTER 1 (ADDRESS: 11Bh) R-0 R-0 MC1OUT MC2OUT U-0 U-0 U-0 U-0 R/W-1 R/W-0 — — — — T1GSS C2SYNC bit 7 bit 0 bit 7 MC1OUT: Mirror Copy of C1OUT bit (CM1CON0<6>) bit 6 MC2OUT: Mirror Copy of C2OUT bit (CM2CON0<6>) bit 5-2 Unimplemented: Read as ‘0’ bit 1 T1GSS: Timer1 Gate Source Select bit 1 = Timer1 gate source is RA4/AN3/T1G/OSC2/CLKOUT 0 = Timer1 gate source is SYNCC2OUT. bit 0 C2SYNC: C2 Output Synchronous Mode bit 1 = C2 output is synchronous to falling edge of TMR1 clock 0 = C2 output is asynchronous Legend: DS41249B-page 68 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 9.2 Comparator Outputs 9.3 The comparator outputs are read through the CM1CON0, COM2CON0 or CM2CON1 registers. CM1CON0 and CM2CON0 each contain the individual comparator output of Comparator 1 and Comparator 2, respectively. CM2CON2 contains a mirror copy of both comparator outputs facilitating a simultaneous read of both comparators. These bits are read-only. The comparator outputs may also be directly output to the RA2/AN2/T0CKI/INT/C1OUT and RC4/C2OUT/PH2 I/O pins. When enabled, multiplexers in the output path of the RA2 and RC4 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 9-1 and Figure 9-2 show the output block diagrams for Comparators 1 and 2, respectively. The TRIS bits will still function as an output enable/ disable for the RA2/AN2/T0CKI/INT/C1OUT and RC4/ C2OUT/PH2 pins while in this mode. The polarity of the comparator outputs can be changed using the C1POL and C2POL bits (CMxCON0<4>). Timer1 gate source can be configured to use the T1G pin or Comparator 2 output as selected by the T1GSS bit (CM2CON1<1>). The Timer1 gate feature can be used to time the duration or interval of analog events. The output of Comparator 2 can also be synchronized with Timer1 by setting the C2SYNC bit (CM2CON1<0>). When enabled, the output of Comparator 2 is latched on the falling edge of Timer1 clock source. If a prescaler is used with Timer1, Comparator 2 is latched after the prescaler. To prevent a race condition, the Comparator 2 output is latched on the falling edge of the Timer1 clock source and Timer1 increments on the rising edge of its clock source. See the Comparator 2 Block Diagram (Figure 9-2) and the Timer1 Block Diagram (Figure 6-1) for more information. It is recommended to synchronize Comparator 2 with Timer1 by setting the C2SYNC bit when Comparator 2 is used as the Timer1 gate source. This ensures Timer1 does not miss an increment if Comparator 2 changes during an increment. Comparator Interrupts The comparator interrupt flags are set whenever there is a change in the output value of its respective comparator. Software will need to maintain information about the status of the output bits, as read from CM2CON0<7:6>, to determine the actual change that has occurred. The CxIF bits, PIR1<4:3>, are the Comparator Interrupt Flags. Each comparator interrupt bit must be reset in software by clearing it to ‘0’. Since it is also possible to write a ‘1’ to this register, a simulated interrupt may be initiated. The CxIE bits (PIE1<4:3>) and the PEIE bit (INTCON<6>) must be set to enable the interrupts. In addition, the GIE bit must also be set. If any of these bits are cleared, the interrupt is not enabled, though the CxIF bits will still be set if an interrupt condition occurs. The comparator interrupt of the PIC16F785 differs from previous designs in that the interrupt flag is set by the mismatch edge and not the mismatch level. This means that the interrupt flag can be reset without the additional step of reading or writing the CMxCON0 register to clear the mismatch registers. When the mismatch registers are not cleared, an interrupt will not occur when the comparator output returns to the previous state. When the mismatch registers are cleared, an interrupt will occur when the comparator returns to the previous state. Note 1: If a change in the CMxCON0 register (CxOUT) should occur when a read operation is being executed (start of the Q2 cycle), then the CxIF (PIR1<4:3>) interrupt flag may not get set. 2: When either comparator is first enabled, bias circuitry in the Comparator module may cause an invalid output from the comparator until the bias circuitry is stable. Allow about 1 μs for bias settling then clear the mismatch condition and interrupt flags before enabling comparator interrupts. 9.4 Effects of Reset A Reset forces all registers to their Reset state. This disables both comparators. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 69 PIC16F785 NOTES: DS41249B-page 70 Preliminary © 2005 Microchip Technology Inc. PIC16F785 10.0 VOLTAGE REFERENCES 10.1.2 There are two voltage references available in the PIC16F785: The voltage referred to as the comparator reference (CVREF) is a variable voltage based on VDD; The voltage referred to as the VR reference (VR) is a fixed voltage derived from a stable band gap source. Each source may be individually routed internally to the comparators or output, buffered or unbuffered, on the RA1/AN1/C12IN0-/VREF/ICSPCLK pin. 10.1 Comparator Reference The comparator module also allows the selection of an internally generated voltage reference for one of the comparator inputs. The VRCON register (Register 10-1) controls the voltage reference module shown in Figure 10-1. 10.1.1 VOLTAGE REFERENCE ACCURACY/ERROR The full range of VSS to VDD cannot be realized due to the construction of the module. The transistors on the top and bottom of the resistor ladder network (Figure 10-1) keep CVREF from approaching VSS or VDD. The exception is when the module is disabled by clearing all CVROE, C1VREN and C2VREN bits. When disabled, the reference voltage is VSS when VR<3:0> is ‘0000’ and the VRR (VRCON<5>) bit is set. This allows the comparators to detect a zero-crossing and not consume CVREF module current. The voltage reference is VDD derived and therefore, the CVREF output changes with fluctuations in VDD. The tested absolute accuracy of the comparator voltage reference can be found in Table 18-8. CONFIGURING THE VOLTAGE REFERENCE The voltage reference can output 32 distinct voltage levels, 16 in a high range and 16 in a low range. The following equation determines the output voltages: EQUATION 10-1: CVREF OUTPUT VOLTAGE VRR = 1 (low range): CVREF = VR<3:0> X VDD/24 VRR = 0 (high range): CVREF = (VDD/4) + (VR<3:0> X VDD/32) FIGURE 10-1: COMPARATOR VOLTAGE REFERENCE BLOCK DIAGRAM 16 Stages 8R R R R R VDD 8R VRR 16-1 Analog MUX CVREN(1) 15 CVREF · · · 0 VR3:VR0 CVROE C1VREN C1VREF to Comparator 1 Input 1 0 C2VREN C2VREF to Comparator 2 Input 1 0 © 2005 Microchip Technology Inc. VR 1.2 V Note 1: See Register 10-1, bits 3-0. Preliminary DS41249B-page 71 PIC16F785 REGISTER 10-1: VRCON – VOLTAGE REFERENCE CONTROL REGISTER (ADDRESS: 99H) R/W-0 R/W-0 (1) C1VREN (1) C2VREN R/W-0 U-0 R/W-0 R/W-0 R/W-0 R/W-0 VRR — VR3 VR2 VR1 VR0 bit 7 bit 0 bit 7 C1VREN: Comparator 1 Voltage Reference Enable bit(1) 1 = CVREF circuit powered on and routed to C1VREF input of comparator 1 0 = 1.2 Volt VR routed to C1VREF input of comparator 1 bit 6 C2VREN: Comparator 2 Voltage Reference Enable bit(1) 1 = CVREF circuit powered on and routed to C2VREF input of comparator 2 0 = 1.2 Volt VR routed to C2VREF input of comparator 2 bit 5 VRR: Comparator Voltage Reference CVREF Range Selection bit 1 = Low Range 0 = High Range bit 4 Unimplemented: Read as ‘0’ bit 3-0 VR<3:0>: Comparator Voltage Reference CVREF Value Selection 0 ≤ VR<3:0> ≤ 15 When VRR = 1 and CVREN = 1: CVREF = (VR<3:0> x VDD/24) When VRR = 0 and CVREN = 1: CVREF = (VDD/4) + (VR<3:0> x VDD/32) When CxVREN = 0 and VREN = 1: CxVREF = 1.2V from VR module Note 1: When C1VREN, C2VREN and CVROE (Register 10-2) are all low, the CVREF circuit is powered down and does not contribute to IDD current. Legend: DS41249B-page 72 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ -n = Value at POR ‘1’ = bit is set ‘0’ = bit is cleared Preliminary x = bit is unknown © 2005 Microchip Technology Inc. PIC16F785 10.2 VR Reference Module The VR Reference module generates a 1.2V nominal output voltage for use by the ADC and comparators. The output voltage can also be brought out to the VREF pin for user applications. This module uses a band gap as a reference. See Table 18-9 for detailed specifications. Register 10-2 shows the control register for the VR module. REGISTER 10-2: REFCON – VOLTAGE REFERENCE CONTROL REGISTER (ADDRESS: 98h) U-0 U-0 R-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 — — BGST VRBB VREN VROE CVROE — bit 7 bit 0 bit 7-6 Unimplemented: Read as ‘0’ bit 5 BGST: Band Gap Reference Voltage Stable Flag bit 1 = Reference is stable 0 = Reference is not stable bit 4 VRBB: Voltage Reference Buffer Bypass bit 1 = VREF output is not buffered. Power is removed from buffer amplifier. 0 = VREF output is buffered(1) bit 3 VREN: Voltage Reference Enable bit (VR = 1.2V nominal) 1 = VR reference is enabled 0 = VR reference is disabled and does not consume any current bit 2 VROE: Voltage Reference Output Enable bit If CVROE = 0: 1 = VREF output on RA1/AN1/C12IN0-/VREF/ICSPCLK pin is 1.2 volt VR analog reference 0 = Disabled, 1.2 volt VR analog reference is used internally only If CVROE = 1: VROE has no effect. bit 1 CVROE: Comparator Voltage Reference Output Enable bit (see Figure 10-2) 1 = VREF output on RA1/AN1/C12IN0-/VREF/ICSPCLK pin is CVREF voltage 0 = VREF output on RA1/AN1/C12IN0-/VREF/ICSPCLK pin is controlled by VROE bit 0 Unimplemented: Read as ‘0’ Note 1: Buffer amplifier common mode limitations require VREF ≤ (VDD - 1.4)V for buffered output. Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 73 PIC16F785 10.2.1 VR STABILIZATION PERIOD When the Voltage Reference module is enabled, it will require some time for the reference and its amplifier circuits to stabilize. The user program must include a small delay routine to allow the module to settle. See Section 18.0 “Electrical Specifications” for the minimum delay requirement. FIGURE 10-2: VR REFERENCE BLOCK DIAGRAM VREN CVREF VRBB(1) CVROE (CVROE + (VREN*VROE)) 1 EN VROUT 1 0 Voltage Reference VRIN 1X RA1/AN1/C12IN0-/VREF 0 Analog Buffer RDY VR To CVREF MUX BGST Note 1: Buffered output requires VRIN = (VDD - 1.4)V. TABLE 10-1: Address REGISTERS ASSOCIATED WITH THE COMPARATOR AND VOLTAGE REFERENCE MODULES Value on: POR, BOR Value on all other Resets Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 CM1CON0 C1ON C1OUT C1OE C1POL C1SP C1R C1CH1 C1CH0 11Ah CM2CON0 C2ON C2OUT C2OE C2POL C2SP C2R C2CH1 C2CH0 0000 0000 0000 0000 11Bh CM2CON1 MC1OUT MC2OUT — — — — T1GSS C2SYNC 00-- --10 00-- --10 85h, 185h TRISA — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111 87h, 187h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111 05h, 105h PORTA — — RA5 RA4 RA3 RA2 RA1 RA0 --xx xxxx --uu uuuu 07h, 107h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx uuuu uuuu 91h ANSEL0 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 ---0 0000 ---0 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 ---0 0000 ---0 — — BGST VRBB VREN VROE CVROE — --00 000- --00 000- VRR — VR3 VR2 VR1 VR0 000- 0000 000- 0000 119h 8Ch PIE1 98h REFCON 99h VRCON — C1VREN C2VREN 0000 0000 0000 0000 Legend: x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used for comparator. DS41249B-page 74 Preliminary © 2005 Microchip Technology Inc. PIC16F785 11.0 OPERATIONAL AMPLIFIER (OPA) MODULE 11.2 The OPA module is enabled by setting the OPAON bit (OPAxCON<7>). When enabled, OPAON forces the output driver of RC3/AN7/C12IN3-/OP1 for OPA1, and RC2/AN6/C12IN2-/OP2 for OPA2, into tri-state to prevent contention between the driver and the OPA output. The OPA module has the following features: • Two independent Operational Amplifiers • External connections to all ports • 3 MHz Gain Bandwidth Product (GBWP) 11.1 Note: Control Registers The OPA1CON register, shown in Register 11-1, controls OPA1. OPA2CON, shown in Register 11-2, controls OPA2. FIGURE 11-1: OPAxCON Register When OPA1 or OPA2 is enabled, the RC3/AN7/C12IN3-/OP1 pin, or RC2/AN6/C12IN2-/OP2 pin, respectively, is driven by the op amp output, not by the PORTC driver. Refer to Table 18-11 for the electrical specifications for the op amp output drive capability. OPA MODULE BLOCK DIAGRAM OPA1CON<OPAON> RC7/AN9/OP1+ OPA1 RC6/AN8/OP1RC3/AN7/C12IN3-/OP1 TO ADC and Comparator MUXs OPA2CON<OPAON> RB5/AN11/OP2+ OPA2 RB4/AN10/OP2RC2/AN6/C12IN2-/OP2 TO ADC and Comparator MUXs © 2005 Microchip Technology Inc. Preliminary DS41249B-page 75 PIC16F785 REGISTER 11-1: OPA1CON – OP AMP 1 CONTROL REGISTER (ADDRESS: 11Ch) R/W-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0 OPAON — — — — — — — bit 7 bit 0 bit 7 OPAON: Op Amp Enable bit 1 = Op Amp 1 is enabled 0 = Op Amp 1 is disabled bit 6-0 Unimplemented: Read as ‘0’ Legend: REGISTER 11-2: 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 OPA2CON – OP AMP 2 CONTROL REGISTER (ADDRESS: 11Dh) R/W-0 U-0 U-0 U-0 U-0 U-0 U-0 U-0 OPAON — — — — — — — bit 7 bit 0 bit 7 OPAON: Op Amp Enable bit 1 = Op Amp 2 is enabled 0 = Op Amp 2 is disabled bit 6-0 Unimplemented: Read as ‘0’ Legend: DS41249B-page 76 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 11.3 Effects of a Reset Leakage current is a measure of the small source or sink currents on the OPA+ and OPA- inputs. To minimize the effect of leakage currents, the effective impedances connected to the OPA+ and OPA- inputs should be kept as small as possible and equal. A device Reset forces all registers to their Reset state. This disables both op amps. 11.4 OPA Module Performance Input offset voltage is a measure of the voltage difference between the OPA+ and OPA- inputs in a closed loop circuit with the OPA in its linear region. The offset voltage will appear as a DC offset in the output equal to the input offset voltage, multiplied by the gain of the circuit. The input offset voltage is also affected by the common mode voltage. Common AC and DC performance specifications for the OPA module: • • • • • Common Mode Voltage Range Leakage Current Input Offset Voltage Open Loop Gain Gain Bandwidth Product (GBWP) Open loop gain is the ratio of the output voltage to the differential input voltage, (OPA+) - (OPA-). The gain is greatest at DC and falls off with frequency. Common mode voltage range is the specified voltage range for the OPA+ and OPA- inputs, for which the OPA module will perform to within its specifications. The OPA module is designed to operate with input voltages between 0 and VDD-1.4V. Behavior for common mode voltages greater than VDD-1.4V, or below 0V, are beyond the normal operating range. TABLE 11-1: Address Gain Bandwidth Product or GBWP is the frequency at which the open loop gain falls off to 0 dB. 11.5 Effects of Sleep When enabled, the op amps continue to operate and consume current while the processor is in Sleep mode. REGISTERS ASSOCIATED WITH THE OPA MODULE Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets — — — — — — — 0--- ---- 0--- ---0--- ---- 11Ch OPA1CON OPAON 11Dh OPA2CON OPAON — — — — — — — 0--- ---- 91h ANSEL0 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 93h ANSEL1 — — — — ANS11 ANS10 ANS9 ANS8 ---- 1111 ---- 1111 — — 86h, 186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 1111 ---- 1111 ---- 87h, 187h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111 Legend: — — x = unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used for the OPA module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 77 PIC16F785 NOTES: DS41249B-page 78 Preliminary © 2005 Microchip Technology Inc. PIC16F785 12.0 ANALOG-TO-DIGITAL CONVERTER (A/D) MODULE The analog-to-digital converter (A/D) allows conversion of an analog input signal to a 10-bit binary representation of that signal. The PIC16F785 has twelve analog I/O inputs, plus two internal inputs, multiplexed into one sample and hold circuit. The output of the sample and hold is connected to the input of the converter. The converter generates a binary result via successive approximation and stores the result in a 10-bit register. The voltage reference used in the conversion is software selectable to either VDD or a voltage applied by the VREF pin. Figure 12-1 shows the block diagram of the A/D on the PIC16F785. FIGURE 12-1: A/D BLOCK DIAGRAM VDD VCFG = 0 VREF RA0/AN0/C1IN+/ICSPDAT VCFG = 1 0 RA1/AN1/C12IN0-/VREF/ICSPCLK RA2/AN2/T0CKI/INT/C1OUT RA4/AN3/T1G/OSC2/CLKOUT RC0/AN4/C2IN+ RC1/AN5/C12IN1-/PH1 RC2/AN6/C12IN2-/OP2 A/D RC3/AN7/C12IN3-/OP1 10 GO/DONE RC6/AN8/OP1RC7/AN9/OP1+ ADFM RB4/AN10/OP2- 10 ADON(1) RB5/AN11/OP2+ ADRESH CVREF 13 VR CHS<3:0> © 2005 Microchip Technology Inc. ADRESL VSS Note 1: When ADON = 0 all input channels are disconnected from ADC (no loading). Preliminary DS41249B-page 79 PIC16F785 12.1 A/D Configuration and Operation There are four registers available to control the functionality of the A/D module: 1. 2. 3. 4. ANSEL0 (Register 12-1) ANSEL1 (Register 12-2) ADCON0 (Register 12-3) ADCON1 (Register 12-4) 12.1.1 12.1.2 Analog voltages on any pin that is defined as a digital input may cause the input buffer to conduct excess current. CHANNEL SELECTION There are fourteen analog channels on the PIC16F785. The CHS<3:0> bits (ADCON0<5:2>) control which channel is connected to the sample and hold circuit. TABLE 12-1: VOLTAGE REFERENCE There are two options for the voltage reference to the A/D converter: either VDD is used or an analog voltage applied to VREF is used. The VCFG bit (ADCON0<6>) controls the voltage reference selection. If VCFG is set, then the voltage on the VREF pin is the reference; otherwise, VDD is the reference. 12.1.4 ANALOG PORT PINS The ANS<11:0> bits (ANSEL1<3:0> and ANSEL0<7:0>) and the TRISA<4,2:0>, TRISB<5:4> and TRISC<7:6,3:0>> bits control the operation of the A/D port pins. Set the corresponding TRISx bits to ‘1’ to set the pin output driver to its high-impedance state. Likewise, set the corresponding ANSx bit to disable the digital input buffer. Note: 12.1.3 CONVERSION CLOCK The A/D conversion cycle requires 11 TAD. The source of the conversion clock is software selectable via the ADCS bits (ADCON1<6:4>). There are seven possible clock options: • • • • • • • FOSC/2 FOSC/4 FOSC/8 FOSC/16 FOSC/32 FOSC/64 FRC (dedicated internal oscillator) For correct conversion, the A/D conversion clock (1/TAD) must be selected to ensure a minimum TAD of 1.6 μs. Table 12-1 shows a few TAD calculations for selected frequencies. TAD VS. DEVICE OPERATING FREQUENCIES A/D Clock Source (TAD) Device Frequency Operation ADCS2:ADCS0 20 MHz 5 MHz 4 MHz 1.25 MHz 2 TOSC 000 100 ns(2) 400 ns(2) 500 ns(2) 1.6 μs 4 TOSC 100 200 ns(2) ns(2) μs(2) 3.2 μs 8 TOSC 001 400 ns(2) 1.6 μs 2.0 μs 6.4 μs 101 ns(2) 3.2 μs 4.0 μs 12.8 μs(3) 16 TOSC 800 800 1.0 μs(3) 25.6 μs(3) 32 TOSC 010 1.6 μs 6.4 μs 64 TOSC 110 3.2 μs 12.8 μs(3) 16.0 μs(3) 51.2 μs(3) μs(1,4) μs(1,4) 2-6 μs(1,4) A/D RC Legend: Note 1: 2: 3: 4: x11 2-6 μs(1,4) 2-6 8.0 2-6 Shaded cells are outside of recommended range. The A/D RC source has a typical TAD time of 4 μs for VDD > 3.0V. These values violate the minimum required TAD time. For faster conversion times, the selection of another clock source is recommended. When the device frequency is greater than 1 MHz, the A/D RC clock source is only recommended if the conversion will be performed during Sleep. DS41249B-page 80 Preliminary © 2005 Microchip Technology Inc. PIC16F785 12.1.5 STARTING A CONVERSION If the conversion must be aborted, the GO/DONE bit can be cleared in software. The ADRESH:ADRESL registers will not be updated with the partially complete A/D conversion sample. Instead, the ADRESH:ADRESL registers will retain the value of the previous conversion. After an aborted conversion, a 2 TAD delay is required before another acquisition can be initiated. Following the delay, an input acquisition is automatically started on the selected channel. The A/D conversion is initiated by setting the GO/DONE bit (ADCON0<1>). When the conversion is complete, the A/D module: • Clears the GO/DONE bit • Sets the ADIF flag (PIR1<6>) • Generates an interrupt (if enabled) Note: FIGURE 12-2: The GO/DONE bit should not be set in the same instruction that turns on the A/D. A/D CONVERSION TAD CYCLES TCY to TAD TAD1 TAD2 TAD3 TAD4 TAD5 TAD6 TAD7 TAD8 b9 b8 b7 b6 b5 b4 b3 TAD9 TAD10 TAD11 b2 b1 b0 Conversion Starts Holding Capacitor is Disconnected from Analog Input (typically 100 ns) Set GO bit 12.1.6 ADRESH and ADRESL registers are loaded, GO bit is cleared, ADIF bit is set, Holding capacitor is connected to analog input CONVERSION OUTPUT The A/D conversion can be supplied in two formats: left or right justified. The ADFM bit (ADCON0<7>) controls the output format. Figure 12-3 shows the output formats. FIGURE 12-3: 10-BIT A/D RESULT FORMAT ADRESH (ADDRESS:1Eh) (ADFM = 0) ADRESL (ADDRESS:9Eh) MSB LSB bit 7 bit 0 bit 7 10-bit A/D Result (ADFM = 1) bit 0 Unimplemented: Read as ‘0’ MSB bit 7 LSB bit 0 Unimplemented: Read as ‘0’ © 2005 Microchip Technology Inc. Preliminary bit 7 bit 0 10-bit A/D Result DS41249B-page 81 PIC16F785 REGISTER 12-1: ANSEL0 – ANALOG SELECT REGISTER (ADDRESS: 91h) R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 R/W-1 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 bit 7 bit 7-0 bit 0 ANS<7:0>: Analog Select bits Analog select between analog or digital function on pins AN<7:0>, respectively. 1 = Analog input. Pin is assigned as analog input.(1) 0 = Digital I/O. Pin is assigned to port or special function. Note 1: Setting a pin to an analog input automatically disables the digital input circuitry, weak pull-ups, and interrupt-on-change, if available. The corresponding TRIS bit must be set to Input mode in order to allow external control of the voltage on the pin. Port reads of pins configured assigned as analog inputs will read as ‘0’. Legend: REGISTER 12-2: 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 ANSEL1 – ANALOG SELECT REGISTER (ADDRESS: 93h) U-0 U-0 U-0 U-0 R/W-1 R/W-1 R/W-1 R/W-1 — — — — ANS11 ANS10 ANS9 ANS8 bit 7 bit 0 bit 7-4 Unimplemented: Read as ‘0’ bit 3-0 ANS<11:8>: Analog Select bits Analog select between analog or digital function on pins AN<11:8>, respectively. 1 = Analog input. Pin is assigned as analog input.(1) 0 = Digital I/O. Pin is assigned to port or special function. Note 1: Setting a pin to an analog input automatically disables the digital input circuitry, weak pull-ups, and interrupt-on-change, if available. The corresponding TRIS bit must be set to Input mode in order to allow external control of the voltage on the pin. Port reads of pins assigned as analog inputs will read as ‘0’. Legend: TABLE 12-2: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared ANALOG SELECT CROSS REFERENCE Mode Analog Select x = Bit is unknown Reference ANS11 ANS10 ANS9 ANS8 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 Analog Channel AN11 AN10 AN9 AN8 AN7 AN6 AN5 AN4 AN3 AN2 AN1 AN0 I/O Pin RB5 RB4 RC7 RC6 RC3 RC2 RC1 RC0 RA4 RA2 RA1 RA0 DS41249B-page 82 Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 12-3: ADCON0 – A/D CONTROL REGISTER (ADDRESS: 1Fh) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 ADFM VCFG CHS3 CHS2 CHS1 CHS0 GO/DONE ADON bit 7 bit 0 bit 7 ADFM: A/D Result Formed Select bit 1 = Right justified 0 = Left justified bit 6 VCFG: Voltage Reference bit 1 = VREF pin 0 = VDD bit 5-2 CHS<3:0>: Analog Channel Select bits 0000 = Channel 00 (AN0) 0001 = Channel 01 (AN1) 0010 = Channel 02 (AN2) 0011 = Channel 03 (AN3) 0100 = Channel 04 (AN4) 0101 = Channel 05 (AN5) 0110 = Channel 06 (AN6) 0111 = Channel 07 (AN7) 1000 = Channel 08 (AN8) 1001 = Channel 09 (AN9) 1010 = Channel 10 (AN10) 1011 = Channel 11 (AN11) 1100 = CVREF 1101 = VR 1110 = Reserved. Do not use. 1111 = Reserved. Do not use. bit 1 GO/DONE: A/D Conversion Status bit 1 = A/D conversion cycle in progress. Setting this bit starts an A/D conversion cycle. This bit is automatically cleared by hardware when the A/D conversion has completed. 0 = A/D conversion completed/not in progress bit 0 ADON: A/D Enable bit 1 = A/D converter module is enabled 0 = A/D converter is shut-off and consumes no operating current 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 83 PIC16F785 REGISTER 12-4: ADCON1 – A/D CONTROL REGISTER 1 (ADDRESS: 9Fh) U-0 R/W-0 R/W-0 R/W-0 U-0 U-0 U-0 U-0 — ADCS2 ADCS1 ADCS0 — — — — bit 7 bit 0 bit 7 Unimplemented: Read as ‘0’ bit 6-4 ADCS<2:0>: A/D Conversion Clock Select bits 000 = FOSC/2 001 = FOSC/8 010 = FOSC/32 x11 = FRC (clock derived from a dedicated internal oscillator = 500 kHz max) 100 = FOSC/4 101 = FOSC/16 110 = FOSC/64 bit 3-0 Unimplemented: Read as ‘0’ Legend: DS41249B-page 84 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 12.1.7 CONFIGURING THE A/D EXAMPLE 12-1: 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 inputs. To determine sample time, see Tables 18-15 and 18-16. After this sample time has elapsed, the A/D conversion can be started. These steps should be followed for an A/D conversion: 1. 2. 3. 4. 5. 6. 7. Configure the A/D module: • Configure analog/digital I/O (ANSx) • Select A/D conversion clock (ADCON1<6:4>) • Configure voltage reference (ADCON0<6>) • Select A/D input channel (ADCON0<5:2>) • Select result format (ADCON0<7>) • Turn on A/D module (ADCON0<0>) Configure A/D interrupt (if desired): • Clear ADIF bit (PIR1<6>) • Set ADIE bit (PIE1<6>) • Set PEIE and GIE bits (INTCON<7:6>) Wait the required acquisition time. Start conversion: • Set GO/DONE bit (ADCON0<1>) Wait for A/D conversion to complete, by either: • Polling for the GO/DONE bit to be cleared (with interrupts disabled); OR • Waiting for the A/D interrupt Read A/D Result register pair (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. © 2005 Microchip Technology Inc. A/D CONVERSION ;This code block configures the A/D ;for polling, Vdd reference, R/C clock ;and RA0 input. ; ;Conversion start and wait for complete ;polling code included. ; BCF STATUS,RP1 ;Bank 1 BSF STATUS,RP0 ; MOVLW B’01110000’ ;A/D RC clock MOVWF ADCON1 BSF TRISA,0 ;Set RA0 to input BSF ANSEL0,0 ;Set RA0 to analog BCF STATUS,RP0 ;Bank 0 MOVLW B’10000001’ ;Right, Vdd Vref, AN0 MOVWF ADCON0 CALL SampleTime ;Wait min sample time BSF ADCON0,GO ;Start conversion BTFSC ADCON0,GO ;Is conversion done? GOTO $-1 ;No, test again MOVF ADRESH,W ;Read upper 2 bits MOVWF RESULTHI BSF STATUS,RP0 ;Bank 1 MOVF ADRESL,W ;Read lower 8 bits BCF STATUS,RP0 ;Bank 0 MOVWF RESULTLO Preliminary DS41249B-page 85 PIC16F785 12.2 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 12-4. The source impedance (RS) and the internal sampling switch (RSS) impedance directly affect the time required to charge the capacitor CHOLD. The sampling switch (RSS) impedance varies over the device voltage (VDD), see Figure 12-4. The maximum recommended impedance for analog sources is 10 kΩ. As the impedance is decreased, the acquisition time may EQUATION 12-1: be decreased. After the analog input channel is selected (changed), this acquisition must be done before the conversion can be started. To calculate the minimum acquisition time, Equation 12-1 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. To calculate the minimum acquisition time, TACQ, see the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). ACQUISITION TIME EXAMPLE Temperature = 50°C and external impedance of 10k Ω 5.0V V DD Assumptions: T ACQ = Amplifier Settling Time + Hold Capacitor Charging Time + Temperature Coefficient = T AMP + T C + T COFF = 2µs + T C + [ ( Temperature - 25°C ) ( 0.05µs/°C ) ] The value for TC can be approximated with the following equations: 1 V AP P LIED ⎛⎝ 1 – ------------⎞⎠ = V C HOLD 2047 ;[1] VCHOLD charged to within 1/2 lsb –T C ----------⎞ ⎛ RC V A PP LIED ⎜ 1 – e ⎟ = V CHOLD ⎝ ⎠ ;[2] VCHOLD charge response to VAPPLIED – Tc ---------⎞ ⎛ 1 RC V A PP LIE D ⎜ 1 – e ⎟ = V AP PLIE D ⎛⎝ 1 – ------------⎞⎠ 2047 ⎝ ⎠ ;combining [1] and [2] Solving for TC: T C = –C HOLD ( R IC + R SS + R S ) ln(1/2047) = – 10pF ( 1k Ω + 7k Ω + 10k Ω ) ln(0.0004885) = 1.37 µs Therefore: T ACQ = 2µ S + 1.37µ S + [ ( 50°C- 25°C ) ( 0.05µ S /°C ) ] = 4.67µ S Note 1: The reference voltage (VREF) has no effect on the equation, since it cancels itself out. 2: The charge holding capacitor (CHOLD) is not discharged after each conversion. 3: The maximum recommended impedance for analog sources is 10 kΩ. This is required to meet the pin leakage specification. DS41249B-page 86 Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 12-4: ANALOG INPUT MODEL VDD RS VA ANx CPIN 5 pF VT = 0.6V VT = 0.6V RIC ≤ 1k Sampling Switch SS RSS CHOLD = DAC capacitance = 10 pF ILEAKAGE ± 500 nA VSS Legend: CPIN = Input Capacitance VT = Threshold Voltage I LEAKAGE = Leakage current at the pin due to various junctions RIC = Interconnect Resistance SS = Sampling Switch CHOLD = Sample/Hold Capacitance (from DAC) © 2005 Microchip Technology Inc. Preliminary 6V 5V VDD 4V 3V 2V RSS 5 6 7 8 9 10 11 Sampling Switch (kΩ) DS41249B-page 87 PIC16F785 12.3 A/D Operation During Sleep The A/D Converter module can operate during Sleep. This requires the A/D clock source to be set to the FRC option. When the RC clock source is selected, the A/D waits one instruction before starting the conversion. This allows the SLEEP instruction to be executed, thus eliminating much of the switching noise from the conversion. When the conversion is complete, the GO/DONE bit is cleared and the result is loaded into the ADRESH:ADRESL registers. If the A/D interrupt is enabled (ADIE and PEIE bits set), the device awakens from Sleep. If the GIE bit (INTCON<7>) is set, the program counter is set to the interrupt vector (0004h). If GIE is clear, the next instruction is executed. If the A/D interrupt is not enabled, the A/D module is turned off, although the ADON bit remains set. FIGURE 12-5: When the A/D clock source is something other than RC, a SLEEP instruction causes the present conversion to be aborted and the A/D module is turned off. The ADON bit remains set. A/D TRANSFER FUNCTION Full-Scale Range 3FFh 3FEh A/D Output Code 3FDh 3FCh 1 LSB ideal 3FBh Full-Scale Transition 004h 003h 002h 001h 000h Analog Input Voltage 1 LSB ideal 0V DS41249B-page 88 Zero-Scale Transition Preliminary VREF © 2005 Microchip Technology Inc. PIC16F785 12.4 Effects of Reset The appropriate analog input channel must be selected and the minimum acquisition done before the “special event trigger” sets the GO/DONE bit (starts a conversion). A device Reset forces all registers to their Reset state. Thus, the A/D module is turned off and any pending conversion is aborted. The ADRESH:ADRESL registers are unchanged. 12.5 If the A/D module is not enabled (ADON is cleared), then the “special event trigger” will be ignored by the A/D module, but will still reset the Timer1 counter. See Section 8.0 “Capture/Compare/PWM (CCP) Module” for more information. Use of the CCP Trigger An A/D conversion can be started by the “special event trigger” of the CCP module. This requires that the CCP1M3:CCP1M0 bits (CCP1CON<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 conversion and the Timer1 counter will be reset to zero. Timer1 is reset to automatically repeat the A/D acquisition period with minimal software overhead (moving the ADRESH:ADRESL to the desired location). TABLE 12-3: Addr Name SUMMARY OF A/D REGISTERS Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets 05h,105h PORTA — — RA5 RA4 RA3 RA2 RA1 RA0 --xx xxxx --uu uuuu 06h,106h PORTB RB7 RB6 RB5 RB4 — — — — xxxx ---- uuuu ---- 07h,107h PORTC RC7 RC6 RC5 RC4 RC3 RC2 RC1 RC0 xxxx xxxx uuuu uuuu GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 xxxx xxxx uuuu uuuu 0Bh,8Bh, INTCON 10Bh,18Bh 0Ch PIR1 1Eh ADRESH 1Fh ADCON0 85h,185h TRISA Most Significant 8 bits of the left justified A/D result or 2 bits of the right justified result ADFM VCFG CHS3 CHS2 CHS1 CHS0 GO/DONE ADON 0000 0000 0000 0000 — — TRISA5 TRISA4 TRISA3 TRISA2 TRISA1 TRISA0 --11 1111 --11 1111 86h,186h TRISB TRISB7 TRISB6 TRISB5 TRISB4 — — — — 1111 ---- 1111 ---- 87h,187h TRISC TRISC7 TRISC6 TRISC5 TRISC4 TRISC3 TRISC2 TRISC1 TRISC0 1111 1111 1111 1111 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 91h ANSEL0 ANS7 ANS6 ANS5 ANS4 ANS3 ANS2 ANS1 ANS0 1111 1111 1111 1111 93h ANSEL1 — — — — ANS11 ANS10 ANS9 ANS8 ---- 1111 ---- 1111 9Eh ADRESL 9Fh ADCON1 Legend: Least Significant 2 bits of the left justified A/D result or 8 bits of the right justified result — ADCS2 ADCS1 ADCS0 — — — — xxxx xxxx uuuu uuuu -000 ---- -000 ---- x = unknown, u = unchanged, – = unimplemented read as ‘0’. Shaded cells are not used for A/D module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 89 PIC16F785 NOTES: DS41249B-page 90 Preliminary © 2005 Microchip Technology Inc. PIC16F785 13.0 TWO-PHASE PWM EQUATION 13-2: The two-phase PWM (Pulse Width Modulator) is a stand-alone peripheral that supports: • Single or dual-phase PWM • Single complementary output PWM with overlap/ delay • Sync input/output to cascade devices for additional phases Setting either, or both, of the PH1EN or PH2EN bits of the PWMCON0 register will activate the PWM module (see Register 13-1). If PH1 is used then TRISC<1> must be cleared to configure the pin as an output. The same is true for TRISC<4> when using PH2. Both PH1EN and PH2EN must be set when using Complementary mode. 13.1 PWM Period The PWM period is derived from the main clock (FOSC), the PWM prescaler and the period counter (see Figure 13-1). The prescale bits (PWMP<1:0>, see Register 13-2) determine the value of the clock divider which divides the system clock (FOSC) to the pwm_clk. This pwm_clk is used to drive the PWM counter. In Master mode, the PWM counter is reset when the count reaches the period count (PER<4:0>, see Register 13-2), which determines the frequency of the PWM. The relationship between the PWM frequency, prescale and period count is shown in Equation 13-1. EQUATION 13-1: PWM FREQUENCY Fosc PWM FREQ = --------------------------------------------------PWMP (2 ⋅ ( PER + 1 ) ) The maximum PWM frequency is FOSC/2, since the period count must be greater than zero. In Slave mode, the period counter is reset by the SYNC input, which is the master device period counter reset. For proper operation, the slave period count should be equal to or greater than that of the master. 13.2 PWM Phase Each enabled phase output is driven active when the phase counter matches the corresponding PWM phase count (PH<4:0>, see Register 13-3 and Register 13-4). The phase output remains true until terminated by a feedback signal from either of the comparators or the auto-shutdown activates. PHASE RESOLUTION 360 Phase DEG = ------------------------( PER + 1 ) 13.3 PWM Duty Cycle Each PWM output is driven inactive, terminating the drive period, by asynchronous feedback through the internal comparators. The duty cycle resolution is in effect infinitely adjustable. Either or both comparators can be used to reset the PWM by setting the corresponding comparator enable bit (CxEN, see Register 13-3). Duty cycles of 100% can be obtained by suppressing the feedback which would otherwise terminate the pulse. The comparator outputs can be “held off”, or blanked, by enabling the corresponding BLANK bit (BLANKx, see Register 13-1) for each phase. The blank bit disables the comparator outputs for 1/2 of a system clock (FOSC), thus ensuring at least Tosc/2 active time for the PWM output. Blanking avoids early termination of the PWM output which may result due to switching transients at the beginning of the cycle. 13.4 Master/Slave Operation Multiple chips can operate together to achieve additional phases by operating one as the master and the others as slaves. When the PWM is configured as a master, the RB7/SYNC pin is an output and generates a high output for one pwm_clk period at the end of each PWM period (see Figure 13-4). When the PWM is configured as a slave, the RB7/ SYNC pin is an input. The high input from a master in this configuration resets the PWM period counter which synchronizes the slave unit at the end of each PWM period. Proper operation of a slave device requires a common external FOSC clock source to drive the master and slave. The PWM prescale value of the slave device must also be identical to that of the master. As mentioned previously, the slave period count value must be greater than or equal to that of the master. The PWM Counter will be reset and held at zero when both PH1EN and PH2EN (PWMCON0<1:0>) are false. If the PWM is configured as a slave, the PWM Counter will remain reset at zero until the first SYNC input is received. Phase granularity is a function of the period count value. For example, if PER<4:0> = 3, each output can be shifted in 90° steps (see Equation 13-2). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 91 PIC16F785 13.5 Active PWM Output Level The PWMASE bit (see Register 13-2) is set by hardware when a shutdown event occurs. If automatic restarts are not enabled (PRSEN = 0, see Register 13-1), PWM operation will not resume until the PWMASE bit is cleared by firmware after the shutdown condition clears. The PWMASE bit can not be cleared as long as the shutdown condition exists. If automatic restarts are not enabled, the auto-shutdown mode can be forced by writing a ‘1’ to the PWMASE bit. The PWM output signal can be made active high or low by setting or resetting the corresponding POL bit (see Register 13-3 and Register 13-4). When POL is ‘1’ the active output state is VOL. When POL is ‘0’ the active output state is VOH. 13.6 Auto-Shutdown and Auto-Restart If automatic restarts are enabled (PRSEN = 1), the PWMASE bit is automatically cleared and PWM operation resumes when the auto-shutdown event clears (VIH on the RA2/AN2/T0CKI/INT/C1OUT pin). When the PWM is enabled, the PWM outputs may be configured for auto-shutdown by setting the PASEN bit (see Register 13-1). VIL on the RA2/AN2/T0CKI/INT/ C1OUT pin will cause a shutdown event if auto-shutdown is enabled. An auto-shutdown event immediately places the PWM outputs in the inactive state (see Section 13.5 “Active PWM Output Level”) and the PWM phase and period counters are reset and held to zero. FIGURE 13-1: TWO-PHASE PWM SIMPLIFIED BLOCK DIAGRAM PH1EN PH2EN PWMP<1:0> PWMASE ÷1,2,4,8 FOSC Prescale pwm_clk MASTER SHUTDOWN PASEN S Phase Counter 0 Res 1 M 5 RB7/SYNC PER<4:0> pwm_count 5 PWMPH1<POL> 5 BLANK1 S PWMPH1<4:0> Q SHUTDOWN PH1EN R pha1 (1) RC1/AN5/C12IN1-/PH1 PWMPH1<C1EN> C1OUT PWMPH1<C2EN> C2OUT PWMPH2<POL> 5 BLANK2 PWMPH2<4:0> SHUTDOWN PH2EN S Q R(1) pha2 RC4/C2OUT/PH2 PWMPH2<C1EN> PWMPH2<C2EN> Note 1: Reset dominant. DS41249B-page 92 Preliminary © 2005 Microchip Technology Inc. PIC16F785 REGISTER 13-1: PWMCON0 – PWM CONTROL REGISTER 0 (ADDRESS: 111h) 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 PASEN BLANK2 BLANK1 SYNC1 SYNC0 PH2EN PH1EN bit 7 bit 0 bit 7 PRSEN: PWM Restart Enable bit 1 = Upon auto-shutdown, the PWMASE shutdown bit clears automatically once the shutdown condition goes away. The PWM restarts automatically. 0 = Upon auto-shutdown, the PWMASE must be cleared in firmware to restart the PWM. bit 6 PASEN: PWM Auto-Shutdown Enable bit 0 = PWM auto-shutdown is disabled 1 = VIL on INT pin will cause auto-shutdown event bit 5 BLANK2: PH2 Blanking bit(1) 1 = The PH2 pin is active for a minimum of 1/2 of an FOSC clock period after it is set 0 = The PH2 pin is reset as soon as the comparator trigger is active bit 4 BLANK1: PH1 Blanking bit(1) 1 = The PH1 pin is active for a minimum of 1/2 of an FOSC clock period after it is set 0 = The PH1 pin is reset as soon as the comparator trigger is active bit 3-2 SYNC<1:0>: SYNC Pin Function bits 0X = SYNC pin not used for PWM. PWM acts as its own master. RB7/SYNC pin is available for general purpose I/O. 10 = SYNC pin acts as system slave, receiving the PWM counter reset pulse 11 = SYNC pin acts as system master, driving the PWM counter reset pulse bit 1 PH2EN: PH2 Pin Enabled bit 1 = The PH2 pin is driven by the PWM signal 0 = The PH2 pin is not used for PWM functions bit 0 PH1EN: PH1 Pin Enabled bit 1 = The PH1 pin is driven by the PWM signal 0 = The PH1 pin is not used for PWM functions Note 1: Blanking is disabled when operating in complementary mode. See COMOD<1:0> bits in the PWMCON1 register (Register 13-5) for more information. Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 93 PIC16F785 REGISTER 13-2: PWMCLK – PWM CLOCK CONTROL REGISTER (ADDRESS: 112h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 PWMASE PWMP1 PWMP0 PER4 PER3 PER2 PER1 PER0 bit 7 bit 0 bit 7 PWMASE: PWM Auto-Shutdown event Status bit 0 = PWM outputs are operating 1 = A shutdown event has occured. PWM outputs are inactive. bit 6-5 PWMP<1:0>: PWM Clock Prescaler bits 00 = pwm_clk = FOSC ÷ 1 01 = pwm_clk = FOSC ÷ 2 10 = pwm_clk = FOSC ÷ 4 11 = pwm_clk = FOSC ÷ 8 bit 4-0 PER<4:0>: PWM Period bits 00000 = Not used. (Period = 1/pwm_clk) 00001 = Period = 2/pwm_clk2 0.... = . . . 01111 = Period = 16/pwm_clk 10000 = Period = 17/pwm_clk 1.... = . . . 11110 = Period = 31/pwm_clk 11111 = Period = 32/pwm_clk Legend: DS41249B-page 94 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 REGISTER 13-3: PWMPH1 – PWM PHASE 1 CONTROL REGISTER (ADDRESS: 113h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 POL C2EN C1EN PH4 PH3 PH2 PH1 PH0 bit 7 bit 0 bit 7 POL: PH1 Output Polarity bit 1 = PH1 Pin is active low 0 = PH1 Pin is active high bit 6 C2EN: Comparator 2 Enable bit When COMOD<1:0> = 00(1) 1 = PH1 is reset when C2OUT goes high 0 = PH1 ignores Comparator 2 When COMOD<1:0> = X1(1) 1 = Complementary drive terminates when C2OUT goes high 0 = Comparator 2 is ignored When COMOD<1:0> = 10(1) C2EN has no effect bit 5 C1EN: Comparator 1 Enable bit When COMOD<1:0> = 00(1) 1 = PH1 is reset when C1OUT goes high 0 = PH1 ignores Comparator 1 When COMOD<1:0> = X1(1) 1 = Complementary drive terminates when C1OUT goes high 0 = Comparator 1 is ignored When COMOD<1:0> = 10(1) C1EN has no effect bit 4-0 PH<4:0>: PWM Phase bits When COMOD<1:0> = 00(1) 00000 = PH1 starts 1 pwm_clk period after falling edge of SYNC pulse. All other PH1 delays are expressed relative to this time. 00001 = PH1 is delayed by 1 pwm_clk pulse ..... = . . . 11111 = PH1 is delayed by 31 pwm_clk pulses When COMOD<1:0> = X1 or 1X(1) 00000 = Complementary drive starts 1 pwm_clk period after falling edge of SYNC pulse. All other delays are expressed relative to this time. 00001 = Complementary drive start is delayed by 1 pwm_clk pulse ..... = . . . 11111 = Complementary drive start is delayed by 31 pwm_clk pulses Note 1: See PWMCON1 register (Register 13-5). 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 © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 95 PIC16F785 REGISTER 13-4: PWMPH2 – PWM PHASE 2 CONTROL REGISTER (ADDRESS: 114h) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 POL C2EN C1EN PH4 PH3 PH2 PH1 PH0 bit 7 bit 0 bit 7 POL: PH2 Output Polarity bit 1 = PH2 Pin is active low 0 = PH2 Pin is active high bit 6 C2EN: Comparator 2 Enable bit When COMOD<1:0> = 00(1) 1 = PH2 is reset when C2OUT goes high 0 = PH2 ignores Comparator 2 When COMOD<1:0> = 1X or X1(1) C2EN has no effect bit 5 C1EN: Comparator 1 Enable bit When COMOD<1:0> = 00(1) 1 = PH2 is reset when C1OUT goes high 0 = PH2 ignores Comparator 1 When COMOD<1:0> = 1X or X1(1) C1EN has no effect bit 4-0 PH<4:0>: PWM Phase bits When COMOD<1:0> = 00(1) 00000 = PH2 starts 1 pwm_clk period after falling edge of SYNC pulse. All other PH2 delays are expressed relative to this time. 00001 = PH2 is delayed by 1 pwm_clk pulse ..... = . . . 11111 = PH2 is delayed by 31 pwm_clk pulses When COMOD<1:0> = 1X(1) 00000 = Complementary drive terminates 1 pwm_clk period after falling edge of SYNC pulse. All other PH2 delays are expressed relative to this time. 00001 = Complementary drive termination is delayed by 1 pwm_clk pulse ..... = . . . 11111 = Complementary drive termination is delayed by 31 pwm_clk pulses When COMOD<1:0> = 01(1) PH<4:0> has no effect. Note 1: See PWMCON1 register (Register 13-5). Legend: DS41249B-page 96 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 FIGURE 13-2: TWO-PHASE PWM AUTO-SHUTDOWN AND SYNC TIMING FOSC PWMP<1:0> = 0X01, PER<4:0> = 0X03 MASTER pwm_clk pwm_count 0 1 2 0 1 2 1 2 3 0 1 2 1 2 3 0 SYNC Phase1 setup: PH<4:0> = 0x00, C1EN = 1, BLANK1 = 0 pha1 SHUTDOWN SLAVE pwm_clk pwm_count 0 1 2 0 3 0 3 0 Phase2 setup: PH<4:0> = 0x02, C2EN = 1, BLANK2 = 1 pha2 FIGURE 13-3: TWO-PHASE PWM START-UP TIMING FOSC PWMP<1:0> = 0X01, PER<4:0> = 0X03 MASTER pwm_clk pwm_count 0 1 2 0 1 2 3 0 1 2 0 SYNC PHnEN SLAVE pwm_clk pwm_count 3 0 1 2 3 PHnEN © 2005 Microchip Technology Inc. Preliminary DS41249B-page 97 PIC16F785 13.7 Example Single Phase Application Figure 13-4 shows an example of a single phase buck voltage regulator application. The PWM output drives Q1 with pulses to alternately charge and discharge L1. C4 holds the charge from L1 during the inactive cycle of the drive period. R4 and C3 form a ramp generator. At the beginning of the PWM period, the PWM output goes high causing the voltage on C3 to rise concurrently with the current in L1. When the voltage across C3 reaches the threshold level present at the positive input of Comparator 1, the comparator output changes and terminates the drive output from the PWM to Q1. When Q1 is not driven, the current path to L1 through Q1 is interrupted, but since the current in L1 cannot stop instantly, the current continues to flow through D2 as L1 discharges into C4. D1 quickly discharges C3 in preparation of the next ramp cycle. FIGURE 13-4: Resistor divider R5 and R6 scale the output voltage, which is inverted and amplified by Op Amp 1, relative to the reference voltage present at the non-inverting pin of the op amp. R3, C5 and C2 form the inverting stabilization gain feedback of the amplifier. The VR reference supplies a stable reference to the noninverting input of the op amp, which is tweaked by the voltage source created by a secondary time based PWM output of the CCP and R1 and C1. Output regulation occurs by the following principle: If the regulator output voltage is too low, then the voltage to the non-inverting input of Comparator 1 will rise, resulting in a higher threshold voltage and, consequently, longer PWM drive pulses into Q1. If the output voltage is too high, then the voltage to the non-inverting input of Comparator 1 will fall, resulting in shorter PWM drive pulses into Q1. EXAMPLE SINGLE PHASE APPLICATION CCP PIC16F785 VR R1 R2 C1 OPA1 VUNREG FOSC FET Driver R3 TWO- Phase C2 C5 PH1 Q1 PWM L1 C4 C1 D2 R4 D1 R5 C3 R6 DS41249B-page 98 Preliminary © 2005 Microchip Technology Inc. PIC16F785 13.8 PWM Configuration When configuring the Two-Phase PWM, care must be taken to avoid active output levels from the PH1 and PH2 pins before the PWM is fully configured. The following sequence is suggested before the TRISC register or any of the Two-Phase PWM control registers are first configured: • Output inactive (OFF) levels to the PORTC RC1/ AN5/C12IN1-/PH1 and RC4/C2OUT/PH2 pins. • Clear TRISC bits 1 and 4 to configure the PH1 and PH2 pins as outputs. • Configure the PWMCLK, PWMPH1, PWMPH2, and PWMCON1 registers. • Configure the PWMCON0 register. 13.9 Complementary Output Mode When COMOD<1:0> = 11, the duty cycle is controlled by the phase counter or feedback through comparator C1 or C2. For example, in this mode, the maximum duty cycle is determined by the values of PWMPH1<4:0> (duty cycle start) and PWMPH2<4:0> (duty cycle end). The duty cycle can be terminated earlier than the maximum by feedback through comparator C1 or C2. 13.9.1 The Complementary Output mode facilitates driving series connected MOSFET drivers by providing dead band drive timing between each phase output (see Figure 13-6). Dead band times are selectable by the CMDLY<4:0> bits of the PWMCON1 register. Delays from 0 to 155 nanoseconds (typical) with a resolution of 5 nanoseconds (typical) are available. The Two-Phase PWM module may be configured to operate in a Complementary Output mode where PH1 and PH2 are always 180 degrees out-of-phase (see Figure 13-5). Three complementary modes are available and are selected by the COMOD<1:0> bits in the PWMCON1 register (see Register 13-5). The difference between the modes is the method by which the PH1 and PH2 outputs switch from the active to the inactive state during the PWM period. 13.9.2 In Complementary mode, there are three methods by which the duty cycle can be controlled. These modes are selected with the COMOD<1:0> bits (see Register 13-5). In each of these modes, the duty cycle is started when the pwm_count = PWMPH1<4:0> and terminates on one of the following: • • • • • • • • • Feedback through C1 or C2. • When the pwm_count equals PWMPH1<4:0>. • Combined feedback and pwm_count match. When COMOD<1:0> = 01, the duty cycle is controlled only by feedback through comparator C1 or C2. In this mode, the active drive cycle starts when pwm_count equals PWMPH1<4:0> and terminates when comparator C1’s output goes high (if enabled by PWMPH1<5> = 1) or when comparator C2 output goes high (if enabled by PWMPH1<6> = 1). When COMOD<1:0> = 10, the duty cycle is controlled only by the PWM Phase counter. In this mode, the active drive cycle starts when the pwm_count equals PWMPH1<4:0> and terminates when the pwm_count equals PWMPH2<4:0>. For example, free running 50% duty cycle can be accomplished by setting COMOD<1:0> = 10 and choosing appropriate values for PWMPH1<4:0> and PWMPH2<4:0>. © 2005 Microchip Technology Inc. DEAD BAND CONTROL OVERLAP CONTROL Overlap timing can be accomplished by configuring the Complementary mode for the desired output polarity and overlap time (as dead time) then swapping the output connections and inverting the outputs. For example, to configure a complementary drive for 55 ns of overlap and an active high drive output on PH1 and an active low drive output on PH2, set the PWM control registers as follows: Connect PH1 driver to PH2 output Connect PH2 driver to PH1 output Initialize PORTC<1> to 1 (PH2 driver off) Initialize PORTC<4> to 0 (PH1 driver off) Set TRISC<1,4> to 0 for output Set PWMPH1<POL> to 1 (Inverted PH1) Set PWMPH2<POL> to 1 (Non-Inverted PH2) Set PWMCON1 for 55 ns delay and desired termination (comparator, count, or both) • Set PWMCON0 desired SYNC and auto-shutdown configuration and to enable PH1 and PH2 13.9.3 SHUTDOWN IN COMPLEMENTARY MODE During shutdown the PH1 and PH2 complementary outputs are forced to their inactive states (see Figure 13-5). When shutdown ceases the PWM outputs revert to their start-up states for the first cycle which is PH1 inactive (output undriven) and PH2 active (output driven). Preliminary DS41249B-page 99 PIC16F785 REGISTER 13-5: PWMCON1 – PWM CONTROL REGISTER 1 (ADDRESS: 110h) U-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 — COMOD1 COMOD0 CMDLY4 CMDLY3 CMDLY2 CMDLY1 CMDLY0 bit 7 bit 0 bit 7 Unimplemented: Read as ‘0’ bit 6-5 COMOD<1:0>: Complementary Mode Select bits(1) 00 = Normal two-phase operation. Complementary mode is disabled. 01 = Complementary operation. Duty cycle is terminated by C1OUT or C2OUT. 10 = Complementary operation. Duty cycle is terminated by PWMPH2<4:0> = pwm_count. 11 = Complementary operation. Duty cycle is terminated by PWMPH2<4:0> = pwm_count or C1OUT or C2OUT. bit 4-0 CMDLY<4:0>: Complementary Drive Dead Time bits (typical) 00000 = Delay = 0 00001 = Delay = 5 ns 00010 = Delay = 10 ns ..... = . . . 11111 = Delay = 155 ns Note 1: PWMCON0<1:0> must be set to ‘11’ for Complementary mode operation. Legend: FIGURE 13-5: 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 COMPLEMENTARY OUTPUT PWM BLOCK DIAGRAM PH1EN pwm_reset PH2EN PS<1:0> PWMASE Shutdown MASTER PASEN FOSC S pwm_clk 0 Phase Res Counter Prescale 1 M 5 RB7/SYNC PER<4:0> pwm_count 5 PWMPH1<POL> 5 Delay PWMPH1<4:0> S Q 5 pha1 RC1/AN5/C12IN1-/PH1 R(1) CMDLY<4:0> 5 5 PWMPH2<POL> 11 PWMPH2<4:0> 10 PWMPH1<C1EN> C1OUT delay S 01 Q pwm_reset PWMPH1<C2EN> C2OUT Note 1: pha2 RC4/C2OUT/PH2 COMOD<1:0> Shutdown R(1) Reset dominant. DS41249B-page 100 Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 13-6: COMPLEMENTARY OUTPUT PWM TIMING FOSC PWMP<1:0> = 0X01, PER<4:0> = 0X03 pwm_clk 3 pwm_count 0 1 2 3 0 0 1 2 1 3 0 1 SYNC C1OUT Phase 1 setup: PH<4:0> = 0x00, C1EN = 1, BLANKx = X, COMOD<1:0> = 0x01 pha1 pha2 Delay Delay Shutdown TABLE 13-1: Address REGISTERS/BITS ASSOCIATED WITH PWM Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets --00 000- — — BGST VRBB VREN VROE CVROE — --00 000- C1VREN C2VREN VRR — VR3 VR2 VR1 VR0 000- 0000 000- 0000 CM1CON0 C1ON C1OUT C1OE C1POL C1SP C1R C1CH1 C1CH0 0000 0000 0000 0000 11Ah CM2CON0 C2ON C2OUT C2OE C2POL 110h PWMCON1 — 111h PWMCON0 PRSEN PASEN BLANK2 112h PWMCLK PWMASE PWMP1 PWMP0 113h PWMPH1 POL C2EN 114h PWMPH2 POL C2EN Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition. Shaded cells are not used by data PWM module. 98h REFCON 99h VRCON 119h © 2005 Microchip Technology Inc. C2SP C2R C2CH1 C2CH0 0000 0000 0000 0000 CMDLY3 CMDLY2 CMDLY1 CMDLY0 -000 0000 -000 0000 BLANK1 SYNC1 SYNC0 PH2EN PH1EN 0000 0000 0000 0000 PER4 PER3 PER2 PER1 PER0 0000 0000 0000 0000 C1EN PH4 PH3 PH2 PH1 PH0 0000 0000 0000 0000 C1EN PH4 PH3 PH2 PH1 PH0 0000 0000 0000 0000 COMOD1 COMOD0 CMDLY4 Preliminary DS41249B-page 101 PIC16F785 NOTES: DS41249B-page 102 Preliminary © 2005 Microchip Technology Inc. PIC16F785 14.0 DATA EEPROM MEMORY The EEPROM data memory is readable and writable during normal operation (full VDD range). This memory is not directly mapped in the register file space. Instead, it is indirectly addressed through the Special Function Registers. There are four SFRs used to read and write this memory: • • • • EECON1 EECON2 (not a physically implemented register) EEDAT EEADR EEDAT holds the 8-bit data for read/write, and EEADR holds the address of the EEPROM location being accessed. The PIC16F785 has 256 bytes of data EEPROM with an address range from 0h to FFh. REGISTER 14-1: The EEPROM data memory allows byte read and write. A byte write automatically erases the location and writes the new data (erase before write). The EEPROM data memory is rated for high erase/write cycles. The write time is controlled by an on-chip timer. The write time will vary with voltage and temperature, as well as from chip-to-chip. Please refer to AC Specifications in Section 18.0 “Electrical Specifications” for exact limits. When the data memory is code-protected, the CPU may continue to read and write the data EEPROM memory. The device programmer can no longer access the data EEPROM data and will read zeroes. Additional information on the data EEPROM is available in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). EEDAT – EEPROM DATA REGISTER (ADDRESS: 9Ah) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 R/W-0 R/W-0 EEDAT2 EEDAT1 R/W-0 EEDAT0 bit 7 bit 7-0 bit 0 EEDATn: Byte Value to Write to or Read From Data EEPROM bits Legend: REGISTER 14-2: 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 EEADR – EEPROM ADDRESS REGISTER (ADDRESS: 9Bh) R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 R/W-0 R/W-0 bit 7 bit 7-0 R/W-0 EEADR2 EEADR1 EEADR0 bit 0 EEADR: Specifies one of 256 locations for EEPROM Read/Write Operation bits Legend: R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared © 2005 Microchip Technology Inc. Preliminary x = Bit is unknown DS41249B-page 103 PIC16F785 14.1 EECON1 and EECON2 Registers The WREN bit, when set, will allow a write operation. On power-up, the WREN bit is clear. The WRERR bit is set when a write operation is interrupted by a MCLR Reset, or a WDT Time-out Reset during normal operation. In these situations, following Reset, the user can check the WRERR bit, clear it and rewrite the location. The EEDAT and EEADR registers are cleared by a Reset. Therefore, the EEDAT and EEADR registers will need to be re-initialized. EECON1 is the control register with four low-order bits physically implemented. The upper four bits are nonimplemented and read as ‘0’s. Control bits RD and WR initiate read and write, respectively. These bits cannot be cleared, only set in software. They are cleared in hardware at completion of the read or write operation. The inability to clear the WR bit in software prevents the accidental, premature termination of a write operation. Interrupt flag EEIF bit (PIR1<7>) is set when write is complete. This bit must be cleared in software. EECON2 is not a physical register. Reading EECON2 will read all ‘0’s. The EECON2 register is used exclusively in the data EEPROM write sequence. Note: REGISTER 14-3: The EECON1, EEDAT and EEADR registers should not be modified during a data EEPROM write (WR bit = 1). EECON1 – EEPROM CONTROL REGISTER (ADDRESS: 9Ch) U-0 U-0 U-0 U-0 R/W-x R/W-0 R/S-0 R/S-0 — — — — WRERR WREN WR RD bit 7 bit 0 bit 7-4 Unimplemented: Read as ‘0’ bit 3 WRERR: EEPROM Error Flag bit 1 = A write operation is prematurely terminated (any MCLR Reset, any WDT Reset during normal operation or BOR reset) 0 = The write operation completed bit 2 WREN: EEPROM Write Enable bit 1 = Allows write cycles 0 = Inhibits write to the data EEPROM bit 1 WR: Write Control bit 1 = Initiates a write cycle (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 data 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.) 0 = Does not initiate an EEPROM read Legend: DS41249B-page 104 R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’ - n = Value at POR ‘1’ = Bit is set ‘0’ = Bit is cleared Preliminary x = Bit is unknown © 2005 Microchip Technology Inc. PIC16F785 14.2 Reading the EEPROM Data Memory After a write sequence has been initiated, clearing the WREN bit will not affect this write cycle. The WR bit will be inhibited from being set unless the WREN bit is set. To read a data memory location, the user must write the address to the EEADR register and then set control bit RD (EECON1<0>), as shown in Example 14-1. The data is available, in the very next cycle, in the EEDAT register. Therefore, it can be read in the next instruction. EEDAT holds this value until another read, or until it is written to by the user (during a write operation). EXAMPLE 14-1: BSF BCF MOVLW MOVWF BSF MOVF 14.3 DATA EEPROM READ STATUS,RP0 ;Bank 1 STATUS,RP1 CONFIG_ADDR ; EEADR ;Address to read EECON1,RD ;EE Read EEDAT,W ;Move data to W At the completion of the write cycle, the WR bit is cleared in hardware and the EE Write Complete Interrupt Flag bit (EEIF) is set. The user can either enable this interrupt or poll this bit. The EEIF bit (PIR1<7>) register must be cleared by software. 14.4 Depending on the application, good programming practice may dictate that the value written to the data EEPROM should be verified (see Example 14-3) to the desired value to be written. EXAMPLE 14-3: BSF BCF MOVF Writing to the EEPROM Data Memory BSF XORWF BTFSS GOTO To write an EEPROM data location, the user must first write the address to the EEADR register and the data to the EEDAT register. Then the user must follow a specific sequence to initiate the write for each byte, as shown in Example 14-2. 14.4.1 DATA EEPROM WRITE BSF BCF BSF BCF BTFSC GOTO MOVLW MOVWF MOVLW MOVWF BSF BSF ;Bank 1 Required Sequence EXAMPLE 14-2: STATUS,RP0 STATUS,RP1 EECON1,WREN INTCON,GIE INTCON,GIE $-2 55h EECON2 AAh EECON2 EECON1,WR INTCON,GIE ;Enable write ;Disable INTs ;See AN-576 ; ;Unlock write ; ; ; ;Start the write ;Enable INTs The write will not initiate if the above sequence is not followed exactly (write 55h to EECON2, write AAh to EECON2, then set WR bit) for each byte. We strongly recommend that interrupts be disabled during this code segment. A cycle count is executed during the required sequence. Any number that is not equal to the required cycles to execute the required sequence will prevent the data from being written into the EEPROM. Additionally, the WREN bit in EECON1 must be set to enable write. This mechanism prevents accidental writes to data EEPROM due to errant (unexpected) code execution (i.e., lost programs). The user should keep the WREN bit clear at all times, except when updating the EEPROM. The WREN bit is not cleared by hardware. © 2005 Microchip Technology Inc. Write Verify WRITE VERIFY STATUS,RP0 ;Bank 1 STATUS,RP1 EEDAT,W ;EEDAT not changed ; from previous write EECON1,RD ;YES, Read the ; value written EEDAT,W STATUS,Z ;Is data the same WRITE_ERR ;No, handle error ;Yes, continue USING THE DATA EEPROM The data EEPROM is a high-endurance, byte addressable array that has been optimized for the storage of frequently changing information (e.g., program variables or other data that are updated often). When variables in one section change frequently, while variables in another section do not change, it is possible to exceed the total number of write cycles to the EEPROM (specification D124) without exceeding the total number of write cycles to a single byte (specifications D120 and D120A). If this is the case, then 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. 14.5 Protect 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 built in. On power-up, WREN is cleared. Also, the Power-up Timer (64 ms duration) prevents EEPROM write. The write initiate sequence and the WREN bit together help prevent an accidental write during: • brown-out • power glitch • software malfunction Preliminary DS41249B-page 105 PIC16F785 14.6 Data EEPROM Operation During Code-Protect Data memory can be code-protected by programming the CPD bit in the Configuration Word (Register 15-1) to ‘0’. When the data memory is code-protected, the CPU is able to read and write data to the data EEPROM. It is recommended to code-protect the program memory when code-protecting data memory. This prevents anyone from programming zeroes over the existing code (which will execute as NOPs) to reach an added routine, programmed in unused program memory, which outputs the contents of data memory. Programming unused locations in program memory to ‘0’ will also help prevent data memory code protection from becoming breached. TABLE 14-1: REGISTERS/BITS ASSOCIATED WITH DATA EEPROM Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets 0Bh,8Bh, INTCON 10Bh,18Bh GIE PEIE T0IE INTE RAIE T0IF INTF RAIF 0000 0000 0000 0000 Address 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 9Ah EEDAT EEDAT7 EEDAT6 EEDAT5 EEDAT4 EEDAT3 EEDAT2 EEDAT1 EEDAT0 0000 0000 0000 0000 9Bh EEADR EEADR7 EEADR6 EEADR5 EEADR4 EEADR3 EEADR2 EEADR1 EEADR0 0000 0000 0000 0000 9Ch EECON1 ---- x000 ---- q000 9Dh EECON2 ---- ---- ---- ---- — — — — WRERR EEPROM Control register 2 (not a physical register) WREN WR RD Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition. Shaded cells are not used by data EEPROM module. DS41249B-page 106 Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.0 SPECIAL FEATURES OF THE CPU The PIC16F785 has a host of features intended to maximize system reliability, minimize cost through elimination of external components, provide power saving features and offer code protection. These features are: 15.1 The configuration bits can be programmed (read as ‘0’), or left unprogrammed (read as ‘1’) to select various device configurations as shown in Register 15-1. These bits are mapped in program memory location 2007h. Note: • Reset: - Power-on Reset (POR) - Power-up Timer (PWRT) - Oscillator Start-up Timer (OST) - Brown-out Reset (BOR) • Interrupts • Watchdog Timer (WDT) • Oscillator selection • Sleep • Code protection • ID Locations • In-Circuit Serial Programming™ (ICSP™) Configuration Bits Address 2007h is beyond the user program memory space. It belongs to the special configuration memory space (2000h3FFFh), which can be accessed only during programming. See “PIC16F785/PS200 Memory Programming Specification” (DS41237) for more information. The PIC16F785 has two timers that offer necessary delays on power-up. One is the Oscillator Start-up Timer (OST), intended to keep the chip in Reset until the crystal oscillator is stable. The other is the Powerup Timer (PWRT), which provides a fixed delay of 64 ms (nominal) on power-up only, designed to keep the part in Reset while the power supply stabilizes. There is also circuitry to reset the device if a brown-out occurs, which can use the Power-up Timer to provide at least a 64 ms Reset. With these three functions onchip, most applications need no external Reset circuitry. The Sleep mode is designed to offer a very low-current Power-down mode. The user can wake-up from Sleep through: • External Reset • Watchdog Timer Wake-up • An interrupt Several oscillator options are also made available to allow the part to fit the application. The INTOSC option saves system cost, while the LP crystal option saves power. A set of configuration bits are used to select various options (see Register 15-1). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 107 PIC16F785 REGISTER 15-1: — — CONFIG – CONFIGURATION WORD (ADDRESS: 2007h) FCMEN(5) IESO BOREN1(1) BOREN0(1) CPD(2,3) CP(2) MCLRE(4) PWRTE WDTE(5) FOSC2 FOSC1 FOSC0 bit 13 bit 0 bit 13-12 Unimplemented: Read as ‘1’ bit 11 FCMEN: Fail-Safe Clock Monitor Enabled bit(5) 1 = Fail-Safe Clock Monitor is enabled 0 = Fail-Safe Clock Monitor is disabled bit 10 IESO: Internal External Switchover bit 1 = Internal External Switchover mode is enabled 0 = Internal External Switchover mode is disabled bit 9-8 BOREN<1:0>: Brown-out Reset Selection bits(1) 11 = BOR enabled 10 = BOR enabled during operation and disabled in Sleep 01 = BOR controlled by SBOREN bit (PCON<4>) 00 = BOR disabled bit 7 CPD: Data Code Protection bit(2,3) 1 = Data memory code protection is disabled 0 = Data memory code protection is enabled bit 6 CP: Code Protection bit(2) 1 = Program memory code protection is disabled 0 = Program memory code protection is enabled bit 5 MCLRE: RA3/MCLR pin function select bit(4) 1 = RA3/MCLR pin function is MCLR 0 = RA3/MCLR pin function is digital input, MCLR internally tied to VDD bit 4 PWRTE: Power-up Timer Enable bit 1 = PWRT disabled 0 = PWRT enabled bit 3 WDTE: Watchdog Timer Enable bit(5) 1 = WDT enabled 0 = WDT disabled and can be enabled by SWDTEN bit (WDTCON<0>) bit 2-0 FOSC<2:0>: Oscillator Selection bits 111 = RC oscillator: CLKOUT function on RA4/AN3/T1G/OSC2/CLKOUT pin, RC on RA5/T1CKI/OSC1/CLKIN 110 = RCIO oscillator: I/O function on RA4/AN3/T1G/OSC2/CLKOUT pin, RC on RA5/T1CKI/OSC1/CLKIN 101 = INTOSC oscillator: CLKOUT function on RA4/AN3/T1G/OSC2/CLKOUT pin, I/O function on RA5/T1CKI/OSC1/CLKIN 100 = INTOSCIO oscillator: I/O function on RA4/AN3/T1G/OSC2/CLKOUT pin, I/O function on RA5/T1CKI/OSC1/CLKIN 011 = EC: I/O function on RA4/AN3/T1G/OSC2/CLKOUT pin, CLKIN on RA5/T1CKI/OSC1/CLKIN 010 = HS oscillator: High-speed crystal/resonator on RA4/AN3/T1G/OSC2/CLKOUT and RA5/T1CKI/OSC1/CLKIN(5) 001 = XT oscillator: Crystal/resonator on RA4/AN3/T1G/OSC2/CLKOUT and RA5/T1CKI/OSC1/CLKIN(5) 000 = LP oscillator: Low-power crystal on RA4/AN3/T1G/OSC2/CLKOUT and RA5/T1CKI/OSC1/CLKIN(5) Note 1: 2: 3: 4: 5: Enabling Brown-out Reset does not automatically enable Power-up Timer. Program memory bulk erase must be performed to turn off code protection. The entire data EEPROM will be erased when the code protection is turned off. When MCLR is asserted in INTOSC or RC mode, the internal clock oscillator is disabled. If the HS, XT, or LP oscillator fails In Fail-safe mode the Watchdog time-out can occur only once after which it will be disabled until the oscillator is restored. Legend: R = Readable -n = Value at POR DS41249B-page 108 W = Writable bit ‘1’ = Bit is set U = Unimplemented bit, read as ‘0’ ‘0’ = Bit is cleared x = Bit is unknown Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.2 Reset The PIC16F785 differentiates between various kinds of Reset: • • • • • • Power-on Reset (POR) WDT Reset during normal operation WDT Reset during Sleep MCLR Reset during normal operation MCLR Reset during Sleep Brown-out Reset (BOR) A simplified block diagram of the On-Chip Reset Circuit is shown in Figure 15-1. Some registers are not affected in any Reset condition; their status is unknown on POR and unchanged in any other Reset. Most other registers are reset to a “Reset state” on: • • • • • They are not affected by a WDT wake-up since this is viewed as the resumption of normal operation. TO and PD bits are set or cleared differently in different Reset situations, as indicated in Table 15-2. These bits are used in software to determine the nature of the Reset. See Table 15-4 for a full description of Reset states of all registers. The MCLR Reset path has a noise filter to detect and ignore small pulses. See Section 18.0 “Electrical Specifications” for pulse width specifications. Power-on Reset MCLR Reset MCLR Reset during Sleep WDT Reset Brown-out Reset (BOR) FIGURE 15-1: SIMPLIFIED BLOCK DIAGRAM OF ON-CHIP RESET CIRCUIT External Reset MCLR/VPP pin Sleep WDT Module WDT Time-out Reset Power-on Reset VDD Rise Detect VDD Brown-out(1) Reset BOREN SBOREN S OST/PWRT OST Chip_Reset 10-bit Ripple Counter R Q OSC1/ CLKI pin PWRT LFINTOSC 11-bit Ripple Counter Enable PWRT Enable OST Note 1: Refer to the Configuration Word register (Register 15-1). © 2005 Microchip Technology Inc. Preliminary DS41249B-page 109 PIC16F785 15.2.1 POWER-ON RESET 15.2.3 The on-chip POR circuit holds the chip in Reset until VDD has reached a high enough level for proper operation. A minimum rise time for VDD is required. See Section 18.0 “Electrical Specifications” for details. If the BOR is enabled, the minimum rise time specification does not apply. The BOR circuitry will keep the device in Reset until VDD reaches VBOR (see Section 15.2.4 “Brown-Out Reset (BOR)”) The POR circuit on this device has a POR re-arm circuit. This circuit is designed to ensure a re-arm of the POR circuit if VDD drops below a preset re-arming voltage (VPARM) for at least the minimum required time. Once VDD has been below the re-arming point for the minimum required time, the POR Reset will reactivate and remain in Reset until VDD returns to a value greater than VPOR. At this point, a 1μs (typical) delay will be initiated to allow VDD to continue to ramp to a voltage safely above VPOR. When the device starts normal operation (exits the Reset condition), device operating parameters (i.e., 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. For additional information, refer to the Application Note AN607, “Power-up Trouble Shooting” (DS00607). 15.2.2 MASTER CLEAR (MCLR) PIC16F785 has a noise filter in the MCLR Reset path. The filter will detect and ignore small pulses. It should be noted that a WDT Reset does not drive MCLR pin low. The behavior of the ESD protection on the MCLR pin has been altered from early devices of this family. Voltages applied to the pin that exceed its specification can result in both MCLR Resets and excessive current beyond the device specification during the ESD event. For this reason, Microchip recommends that the MCLR pin no longer be tied directly to VDD. The use of an RC network, as shown in Figure 15-1, is suggested. An internal MCLR option is enabled by clearing the MCLRE bit in the Configuration Word. When cleared, MCLR is internally tied to VDD and an internal Weak Pull-up is enabled for the MCLR pin. In-Circuit Serial Programming is not affected by selecting the internal MCLR option. DS41249B-page 110 POWER-UP TIMER (PWRT) The Power-up Timer provides a fixed 64 ms (nominal) time out on power-up only, from POR or Brown-out Reset. The Power-up Timer operates from the 31 kHz LFINTOSC oscillator. For more information, see Section 3.4 “Internal Clock Modes”. The chip is kept in Reset as long as PWRT is active. The PWRT delay allows the VDD to rise to an acceptable level. A configuration bit, PWRTE can disable (if ‘1’) or enable (if ‘0’) the Power-up Timer. The Power-up Timer should be enabled when Brown-out Reset is enabled, although it is not required. The Power-up Time Delay will vary from chip-to-chip and vary due to: • VDD variation • Temperature variation • Process variation See DC parameters for details “Electrical Specifications”). 15.2.4 (Section 18.0 BROWN-OUT RESET (BOR) The BOREN0 and BOREN1 bits in the Configuration Word select one of four BOR modes. Two modes have been added to allow software or hardware control of the BOR enable. When BOREN<1:0> = 01, the SBOREN bit (PCON<4>) enables/disables the BOR allowing it to be controlled in software. By selecting BOREN<1:0>, the BOR is automatically disabled in Sleep to conserve power and enabled on wake-up. In this mode, the SBOREN bit is disabled. See Register 15-1 for the Configuration Word definition. If VDD falls below VBOR for greater than parameter (TBOR), see Section 18.0 “Electrical Specifications”, the Brown-out situation will reset the device. This will occur regardless of VDD slew rate. A Reset is not assured if VDD falls below VBOR for less than parameter (TBOR). On any Reset (Power-on, Brown-out Reset, Watchdog, etc.), the chip will remain in Reset until VDD rises above VBOR (see Figure 15-2). The Power-up Timer will now be invoked, if enabled, and will keep the chip in Reset an additional 64 ms. Note: The Power-up Timer is enabled by the PWRTE bit in the Configuration Word. 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 re-initialized. Once VDD rises above VBOR, the Power-up Timer will execute a 64 ms Reset. Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.2.5 BOR CALIBRATION The PIC16F785 stores the BOR calibration values in fuses located in the Calibration Word (2008h). The Calibration Word is not erased when using the specified bulk erase sequence in the “PIC16F785/PS200 Memory Programming Specification” (DS41237) and thus, does not require reprogramming. FIGURE 15-2: Note: BROWN-OUT SITUATIONS VDD Internal Reset VBOR 64 ms(1) VDD Internal Reset VBOR <64 ms 64 ms(1) VDD VBOR Internal Reset Note 1: Address 2008h is beyond the user program memory space. It belongs to the special configuration memory space (2000h3FFFh), which can be accessed only during programming. See “PIC16F785/PS200 Memory Programming Specification” (DS41237) for more information. 64 ms(1) 64 ms delay only if PWRTE bit is programmed to ‘0’. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 111 PIC16F785 15.2.6 TIME-OUT SEQUENCE 15.2.7 On power-up, the time-out sequence is as follows: first, PWRT time out is invoked after POR has expired, then OST is activated after the PWRT time out has expired. The total time out will vary based on oscillator configuration and PWRTE bit status. For example, in EC mode with PWRTE bit equal to ‘1’ (PWRT disabled), there will be no time out at all. Figure 15-3, Figure 15-4 and Figure 15-5 depict time-out sequences. The device can execute code from the INTOSC, while OST is active by enabling Two-Speed Start-up or Fail-Safe Monitor (see Section 3.6.2 “Two-Speed Start-up Sequence” and Section 3.7 “Fail-Safe Clock Monitor”). The Power Control register PCON (address 8Eh) has two Status bits to indicate what type of Reset that last occurred. Bit 0 is BOR (Brown-out Reset). BOR is unknown on Power-on Reset. It must then be set by the user and checked on subsequent Resets to see if BOR = 0, indicating that a Brown-out has occurred. The BOR Status bit is a “don’t care” and is not necessarily predictable if the brown-out circuit is disabled (BOREN<1:0> = 00 in the Configuration Word). Bit 1 is POR (Power-on Reset). It is a ‘0’ on Power-on Reset and unaffected otherwise. The user must write a ‘1’ to this bit following a Power-on Reset. On a subsequent Reset, if POR is ‘0’, it will indicate that a Power-on Reset has occurred (i.e., VDD may have gone too low). Since the time outs occur from the POR pulse, if MCLR is kept low long enough, the time outs will expire. Then bringing MCLR high will begin execution immediately (see Figure 15-4). This is useful for testing purposes or to synchronize more than one PIC16F785 device operating in parallel. For more information, see Section 15.2.4 “Brown-Out Reset (BOR)”. Table 15-5 shows the Reset conditions for some special registers, while Table 15-4 shows the Reset conditions for all the registers. TABLE 15-1: POWER CONTROL (PCON) REGISTER TIME OUT IN VARIOUS SITUATIONS Power-up Brown-out Reset PWRTE = 0 PWRTE = 1 PWRTE = 0 PWRTE = 1 Wake-up from Sleep XT, HS, LP TPWRT + 1024•TOSC 1024•TOSC TPWRT + 1024•TOSC 1024•TOSC 1024•TOSC RC, EC, INTOSC TPWRT — TPWRT — — Oscillator Configuration TABLE 15-2: STATUS/PCON BITS AND THEIR SIGNIFICANCE POR BOR TO PD Condition 0 x 1 1 Power-on Reset 1 0 1 1 Brown-out Reset u u 0 u WDT Reset u u 0 0 WDT Wake-up u u u u MCLR Reset during normal operation u u 1 0 MCLR Reset during Sleep Legend: u = unchanged, x = unknown TABLE 15-3: Address SUMMARY OF REGISTERS ASSOCIATED WITH BROWN-OUT Name 03h, 103h STATUS 83h, 183h Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Value on: POR, BOR Value on all other Resets(1) IRP RP1 RP0 TO PD Z DC C 0001 1xxx 000q quuu — — — SBOREN — — POR BOR ---1 --qq ---u --uu 8Eh PCON Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition. Shaded cells are not used by BOR. Other (non Power-up) Resets include MCLR Reset and Watchdog Timer Reset during normal operation. Note 1: DS41249B-page 112 Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 15-3: TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 1 VDD MCLR Internal POR TPWRT PWRT Time-out TOST OST Time-out Internal Reset TIME-OUT SEQUENCE ON POWER-UP (DELAYED MCLR): CASE 2 FIGURE 15-4: VDD MCLR Internal POR TPWRT PWRT Time-out TOST OST Time-out Internal Reset FIGURE 15-5: TIME-OUT SEQUENCE ON POWER-UP (MCLR WITH VDD) VDD MCLR Internal POR TPWRT PWRT Time-out TOST OST Time-out Internal Reset © 2005 Microchip Technology Inc. Preliminary DS41249B-page 113 PIC16F785 TABLE 15-4: INITIALIZATION CONDITION FOR REGISTERS Address Power-on Reset • MCLR Reset • WDT Reset • Brown-out Reset(1) — xxxx xxxx uuuu uuuu uuuu uuuu INDF 00h/80h xxxx xxxx xxxx xxxx uuuu uuuu TMR0 01h xxxx xxxx uuuu uuuu uuuu uuuu 02h/82h 0000 0000 0000 0000 Register W PCL • Wake-up from Sleep through interrupt • Wake-up from Sleep through WDT time out PC + 1(3) (4) STATUS 03h/83h 0001 1xxx 000q quuu FSR 04h/84h uuuq quuu(4) xxxx xxxx uuuu uuuu uuuu uuuu PORTA 05h --x0 x000(6) --u0 u000(7) --uu uuuu PORTB 06h xx00 ----(6) uu00 ----(7) uuuu ---- 07h 0000(6) 00uu uuuu(7) uuuu uuuu PORTC 00xx PCLATH 0Ah/8Ah ---0 0000 ---0 0000 ---u uuuu INTCON 0Bh/8Bh 0000 0000 0000 0000 uuuu uuuu(2) PIR1 0Ch 0000 0000 0000 0000 uuuu uuuu(2) TMR1L 0Eh xxxx xxxx uuuu uuuu uuuu uuuu TMR1H 0Fh xxxx xxxx uuuu uuuu uuuu uuuu T1CON 10h 0000 0000 uuuu uuuu uuuu uuuu TMR2 11h 0000 0000 0000 0000 uuuu uuuu T2CON 12h -000 0000 -000 0000 -uuu uuuu CCPR1L 13h xxxx xxxx uuuu uuuu uuuu uuuu CCPR1H 14h xxxx xxxx uuuu uuuu uuuu uuuu CCP1CON 15h --00 0000 --00 0000 --uu uuuu WDTCON 18h ---0 1000 ---0 1000 ---u uuuu ADRESH 1Eh xxxx xxxx uuuu uuuu uuuu uuuu ADCON0 1Fh 0000 0000 0000 0000 uuuu uuuu OPTION_REG 81h 1111 1111 1111 1111 uuuu uuuu TRISA 85h --11 1111 --11 1111 --uu uuuu TRISB 86h 1111 ---- 1111 ---- uuuu ---- TRISC 87h 1111 1111 1111 1111 uuuu uuuu PIE1 8Ch 0000 0000 0000 0000 uuuu uuuu PCON 8Eh ---1 --0x ---u --uq(1,5) ---u --uu OSCCON 8Fh -110 x000 -110 x000 -uuu uuuu OSCTUNE 90h ---0 0000 ---u uuuu ---u uuuu ANSEL0 91h 1111 1111 1111 1111 uuuu uuuu PR2 92h 1111 1111 1111 1111 1111 1111 Legend: Note 1: 2: 3: 4: 5: 6: 7: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition. If VDD goes too low, Power-on Reset will be activated and registers will be affected differently. One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). See Table 15-5 for Reset value for specific condition. If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u. Analog channels read 0 but data latches are unknown. Analog channels read 0 but data latches are unchanged. DS41249B-page 114 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 15-4: INITIALIZATION CONDITION FOR REGISTERS (CONTINUED) • MCLR Reset • WDT Reset (Continued) • Brown-out Reset(1) • Wake-up from Sleep through interrupt • Wake-up from Sleep through WDT time out Address Power-on Reset ANSEL1 93h ---- 1111 ---- 1111 ---- uuuu WPUA 95h --11 1111 --11 1111 --uu uuuu IOCA 96h --00 0000 --00 0000 --uu uuuu REFCON 98h --00 000- --00 000- --uu uuu- VRCON 99h 000- 0000 000- 0000 uuu- uuuu EEDAT 9Ah 0000 0000 0000 0000 uuuu uuuu EEADR 9Bh 0000 0000 0000 0000 uuuu uuuu EECON1 9Ch ---- x000 ---- q000 ---- uuuu EECON2 9Dh ---- ---- ---- ---- ---- ---- ADRESL 9Eh xxxx xxxx uuuu uuuu uuuu uuuu ADCON1 9Fh -000 ---- -000 ---- -uuu ---- PWMCON1 110h -000 0000 -000 0000 -uuu uuuu PWMCON0 111h 0000 0000 0000 0000 uuuu uuuu PWMCLK 112h 0000 0000 0000 0000 uuuu uuuu PWMPH1 113h 0000 0000 0000 0000 uuuu uuuu PWMPH2 114h 0000 0000 0000 0000 uuuu uuuu CM1CON0 119h 0000 0000 0000 0000 uuuu uuuu CM2CON0 11Ah 0000 0000 0000 0000 uuuu uuuu CM2CON1 11Bh 00-- --10 00-- --10 uu-- --uu OPA1CON 11Ch 0--- ---- 0--- ---- u--- ---- OPA2CON 11Dh 0--- ---- 0--- ---- u--- ---- Register Legend: Note 1: 2: 3: 4: 5: 6: 7: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’, q = value depends on condition. If VDD goes too low, Power-on Reset will be activated and registers will be affected differently. One or more bits in INTCON and/or PIR1 will be affected (to cause wake-up). When the wake-up is due to an interrupt and the GIE bit is set, the PC is loaded with the interrupt vector (0004h). See Table 15-5 for Reset value for specific condition. If Reset was due to brown-out, then bit 0 = 0. All other Resets will cause bit 0 = u. Analog channels read 0 but data latches are unknown. Analog channels read 0 but data latches are unchanged. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 115 PIC16F785 TABLE 15-5: INITIALIZATION CONDITION FOR SPECIAL REGISTERS Program Counter STATUS Register PCON Register Power-on Reset 000h 0001 1xxx ---1 --0x MCLR Reset during normal operation 000h 000u uuuu ---u --uu MCLR Reset during Sleep 000h 0001 0uuu ---u --uu 000h 0000 uuuu ---u --uu PC + 1 uuu0 0uuu ---u --uu Condition WDT Reset WDT Wake-up Brown-out Reset Interrupt Wake-up from Sleep 000h 0001 1uuu ---1 --10 PC + 1(1) uuu1 0uuu ---u --uu Legend: u = unchanged, x = unknown, – = unimplemented bit, reads as ‘0’. Note 1: When the wake-up is due to an interrupt and global enable bit GIE is set, the PC is loaded with the interrupt vector (0004h) after execution of PC+1. DS41249B-page 116 Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.3 Interrupts For external interrupt events, such as the INT pin or PORTA change interrupt, the interrupt latency will be three or four instruction cycles. The exact latency depends upon when the interrupt event occurs (see Figure 15-7). The latency is the same for one or twocycle instructions. Once in the Interrupt Service Routine, the source(s) of the interrupt can be determined by polling the interrupt flag bits. The interrupt flag bit(s) must be cleared in software before re-enabling interrupts to avoid multiple interrupt requests. The PIC16F785 has 11 sources of interrupt: • • • • • • • • • • External Interrupt RA2/INT TMR0 Overflow Interrupt PORTA Change Interrupt 2 Comparator Interrupts A/D Interrupt Timer1 Overflow Interrupt Timer2 Match Interrupt EEPROM Data Write Interrupt Fail-Safe Clock Monitor Interrupt CCP Interrupt Note 1: Individual interrupt flag bits are set, regardless of the status of their corresponding mask bit or the GIE bit. 2: When an instruction that clears the GIE bit is executed, any interrupts that were pending for execution in the next cycle are ignored. The interrupts, which were ignored, are still pending to be serviced when the GIE bit is set again. The Interrupt Control register (INTCON) and Peripheral Interrupt register (PIR1) record individual interrupt requests in flag bits. The INTCON register also has individual and global interrupt enable bits. A Global Interrupt Enable bit, GIE (INTCON<7>) enables (if set) all unmasked interrupts, or disables (if cleared) all interrupts. Individual interrupts can be disabled through their corresponding enable bits in INTCON register and PIE1 register. GIE is cleared on Reset. For additional information on Timer1, Timer2, comparators, A/D, Data EEPROM or CCP modules, refer to the respective peripheral section. The Return from Interrupt instruction, RETFIE, exits interrupt routine, as well as sets the GIE bit, which re-enables unmasked interrupts. The following interrupt flags are contained in the INTCON register: • INT Pin Interrupt • PORTA Change Interrupt • TMR0 Overflow Interrupt The peripheral interrupt flags are contained in the special register PIR1. The corresponding interrupt enable bit is contained in special register PIE1. The following interrupt flags are contained in the PIR1 register: • • • • • • • EEPROM Data Write Interrupt A/D Interrupt 2 Comparator Interrupts Timer1 Overflow Interrupt Timer2 Match Interrupt Fail-Safe Clock Monitor Interrupt CCP Interrupt When an interrupt is serviced: • The GIE is cleared to disable any further interrupt • The return address is PUSHed onto the stack • The PC is loaded with 0004h © 2005 Microchip Technology Inc. Preliminary DS41249B-page 117 PIC16F785 15.3.1 RA2/AN2/T0CKI/INT/C1OUT INTERRUPT 15.3.2 External interrupt on RA2/AN2/T0CKI/INT/C1OUT pin is edge-triggered; either rising, if INTEDG bit (OPTION_REG<6>) is set, or falling, if INTEDG bit is clear. When a valid edge appears on the RA2/AN2/ T0CKI/INT/C1OUT pin, the INTF bit (INTCON<1>) is set. This interrupt can be disabled by clearing the INTE control bit (INTCON<4>). The INTF bit must be cleared in software in the Interrupt Service Routine before reenabling this interrupt. The RA2/AN2/T0CKI/INT/ C1OUT interrupt can wake-up the processor from Sleep if the INTE bit was set prior to going into Sleep. The status of the GIE bit decides whether or not the processor branches to the interrupt vector following wake-up (0004h). See Section 15.6 “Power-Down Mode (Sleep)” for details on Sleep and Figure 15-9 for timing of wake-up from Sleep through RA2/AN2/ T0CKI/INT/C1OUT interrupt. Note: TMR0 INTERRUPT An overflow (FFh → 00h) in the TMR0 register will set the T0IF (INTCON<2>) bit. The interrupt can be enabled/disabled by setting/clearing T0IE (INTCON<5>) bit. See Section 5.0 “Timer0 Module” for operation of the Timer0 module. 15.3.3 PORTA INTERRUPT An input change on PORTA change sets the RAIF (INTCON<0>) bit. The interrupt can be enabled/ disabled by setting/clearing the RAIE (INTCON<3>) bit. Plus, individual pins can be configured through the IOCA register. Note: If a change on the I/O pin should occur when the read operation is being executed (start of the Q2 cycle), then the RAIF interrupt flag may not get set. The ANSEL0 (91h), and ANSEL1 (93h) registers must be initialized to configure an analog channel as a digital input. Pins configured as analog inputs will read ‘0’. FIGURE 15-6: INTERRUPT LOGIC IOC-RA0 IOCA0 IOC-RA1 IOCA1 IOC-RA2 IOCA2 IOC-RA3 IOCA3 IOC-RA4 IOCA4 IOC-RA5 IOCA5 TMR2IF TMR2IE TMR1IF TMR1IE C1IF C1IE C2IF C2IE Wake-up (If in Sleep mode)(1) T0IF T0IE INTF INTE RAIF RAIE Interrupt to CPU PEIE GIE ADIF ADIE EEIF EEIE OSFIF OSFIE CCP1IF CCP1IE DS41249B-page 118 Note 1: Some peripherals depend upon the system clock for operation. Since the system clock is suspended during Sleep, only those peripherals which do not depend upon the system clock will wake the part from Sleep. See Section 15.6.1 “Wake-up from Sleep”. Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 15-7: INT PIN INTERRUPT TIMING Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 OSC1 CLKOUT(3) (4) INT pin (1) (1) INTF Flag (INTCON<1>) Interrupt Latency (2) (5) GIE bit (INTCON<7>) INSTRUCTION FLOW PC Inst (PC) Instruction Executed Inst (PC - 1) Note 1: 2: 3: 4: 5: Dummy Cycle 0005h Inst (0004h) Inst (0005h) Dummy Cycle Inst (0004h) INTF flag is sampled here (every Q1). Asynchronous interrupt latency = 3-4 TCY. Synchronous latency = 3 TCY, where TCY = instruction cycle time. Latency is the same whether Inst (PC) is a single cycle or a 2-cycle instruction. CLKOUT is available only in INTOSC and RC Oscillator modes. For minimum width of INT pulse, refer to AC specifications in Section 18.0 “Electrical Specifications”. INTF is enabled to be set any time during the Q4-Q1 cycles. TABLE 15-6: Address — Inst (PC + 1) Inst (PC) 0004h PC + 1 PC + 1 PC Instruction Fetched SUMMARY OF INTERRUPT REGISTERS Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Value on all other Resets Bit 1 Bit 0 Value on: POR, BOR INTF RAIF 0000 0000 0000 0000 0Bh, 8Bh INTCON GIE PEIE T0IE INTE RAIE T0IF 0Ch PIR1 EEIF ADIF CCP1IF C2IF C1IF OSFIF TMR2IF TMR1IF 0000 0000 0000 0000 8Ch PIE1 EEIE ADIE CCP1IE C2IE C1IE OSFIE TMR2IE TMR1IE 0000 0000 0000 0000 Legend: x = unknown, u = unchanged, – = unimplemented read as ‘0’, q = value depends upon condition. Shaded cells are not used by the Interrupt module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 119 PIC16F785 15.4 Context Saving During Interrupts During an interrupt, only the return PC value is saved on the stack. Typically, users may wish to save key registers during an interrupt (e.g., W and STATUS registers). This must be implemented in software. Since the last 16 bytes of all banks are common in the PIC16F785 (see Figure 2-2), temporary holding registers W_TEMP and STATUS_TEMP should be placed in here. These 16 locations do not require banking, therefore, making it easier to save and restore context. The same code shown in Example 15-1 can be used to: • • • • • Store the W register Store the STATUS register Execute the ISR code Restore the Status (and Bank Select Bit register) Restore the W register Note: The PIC16F785 normally does not require saving the PCLATH. However, if computed GOTO’s are used in the ISR and the main code, the PCLATH must be saved and restored in the ISR. EXAMPLE 15-1: SAVING STATUS AND W REGISTERS IN RAM MOVWF SWAPF CLRF MOVWF : :(ISR) : SWAPF W_TEMP STATUS,W STATUS STATUS_TEMP MOVWF SWAPF SWAPF STATUS W_TEMP,F W_TEMP,W ;Copy ;Swap ;bank ;Save W to TEMP register status to be saved into W (swap does not affect status) 0, regardless of current bank, Clears IRP,RP1,RP0 status to bank zero STATUS_TEMP register ;Insert user code here STATUS_TEMP,W DS41249B-page 120 ;Swap STATUS_TEMP register into W ;(sets bank to original state) ;Move W into Status register ;Swap W_TEMP ;Swap W_TEMP into W Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.5 Watchdog Timer (WDT) For PIC16F785, the WDT has been modified from previous PIC16F785 devices. The new WDT is code and functionally compatible with previous PIC16F785 WDT modules and adds a 16-bit prescaler to the WDT. This allows the user to scale the value for the WDT and TMR0 at the same time. In addition, the WDT time out value can be extended to 268 seconds. WDT is cleared under certain conditions described in Table 15-7. 15.5.1 WDT OSCILLATOR The WDT derives its time base from the 31 kHz LFINTOSC. The LTS bit does not reflect that the LFINTOSC is enabled (OSCON<1>). The value of WDTCON is ‘---0 1000’ on all Resets. This gives a nominal time base of 16 ms, which is compatible with the time base generated with previous PIC16F785 microcontroller versions. Note: A new prescaler has been added to the path between the INTRC and the multiplexers used to select the path for the WDT. This prescaler is 16 bits and can be programmed to divide the INTRC by 128 to 65536, giving the time base used for the WDT a nominal range of 1 ms to 268s. 15.5.2 WDT CONTROL The WDTE bit is located in the Configuration Word. When set, the WDT runs continuously. When the WDTE bit in the Configuration Word register is set, the SWDTEN bit (WDTCON<0>) has no effect. If WDTE is clear, then the SWDTEN bit can be used to enable and disable the WDT. Setting the bit will enable it and clearing the bit will disable it. The PSA and PS<2:0> bits (OPTION_REG) have the same function as in previous versions of the PIC16F785 family of microcontrollers. See Section 5.0 “Timer0 Module” for more information. When the Oscillator Start-up Timer (OST) is invoked, the WDT is held in Reset, because the WDT Ripple Counter is used by the OST to perform the oscillator delay count. When the OST count has expired, the WDT will begin counting (if enabled). FIGURE 15-8: WATCHDOG TIMER BLOCK DIAGRAM From TMR0 Clock Source 0 Prescaler(1) 16-bit WDT Prescaler 1 8 PSA 31 kHz LFINTOSC Clock PS<2:0> WDTPS<3:0> TO TMR0 0 1 PSA WDTE from Configuration Word SWDTEN from WDTCON WDT time-out Note 1: TABLE 15-7: This is the shared Timer0/WDT prescaler. See Section 5.4 “Prescaler” for more information. WDT STATUS Conditions WDT WDTE = 0 CLRWDT command Cleared OSC FAIL detected Exit Sleep + System Clock = T1OSC, EXTRC, INTRC, EXTCLK Exit Sleep + System Clock = XT, HS, LP © 2005 Microchip Technology Inc. Cleared until the end of OST Preliminary DS41249B-page 121 PIC16F785 REGISTER 15-2: WDTCON – WATCHDOG TIMER CONTROL REGISTER (ADDRESS: 18h) U-0 U-0 U-0 — — — R/W-0 R/W-1 R/W-0 R/W-0 R/W-0 WDTPS3 WDTPS2 WDTPS1 WDTPS0 SWDTEN(1) bit 7 bit 0 bit 7-5 Unimplemented: Read as ‘0’ bit 4-1 WDTPS<3:0>: Watchdog Timer Period Select bits Bit Value = Prescale Rate 0000 = 1:32 0001 = 1:64 0010 = 1:128 0011 = 1:256 0100 = 1:512 (Reset value) 0101 = 1:1024 0110 = 1:2048 0111 = 1:4096 1000 = 1:8192 1001 = 1:16384 1010 = 1:32768 1011 = 1:65536 1100 = reserved 1101 = reserved 1110 = reserved 1111 = reserved bit 0 SWDTEN: Software Enable or Disable the Watchdog Timer bit(1) 1 = WDT is turned on 0 = WDT is turned off (Reset value) Note 1: If WDTE configuration bit = 1, then WDT is always enabled, irrespective of this control bit. If WDTE configuration bit = 0, then it is possible to turn WDT on/off with this control bit. Legend: TABLE 15-8: Address Name STATUS 18h WDTCON OPTION_REG (1) 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 SUMMARY OF WATCHDOG TIMER REGISTERS 03h, 103h 83h, 183h 81h/ 181h R = Readable bit Value on all other resets Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 IRP RP1 RPO TO PD Z DC C — — — WDTPS3 WDTPS2 WSTPS1 WDTPS0 RAPU INTEDG T0CS T0SE PSA PS2 PS1 PS0 1111 1111 1111 1111 CPD CP MCLRE PWRTE WDTE FOSC2 FOSC1 FOSC0 uuuu uuuu uuuu uuuu 2007h CONFIG Legend: Note 1: Shaded cells are not used by the Watchdog Timer. See Register 15-1 for operation of all Configuration Word bits. DS41249B-page 122 Value on: POR,BOR Bit 7 Preliminary 0001 1xxx 000q quuu SWDTEN ---0 1000 ---0 1000 © 2005 Microchip Technology Inc. PIC16F785 15.6 Power-Down Mode (Sleep) The Power-down mode is entered by executing a SLEEP instruction. If the Watchdog Timer is enabled: • • • • • WDT will be cleared but keeps running. PD bit in the STATUS register is cleared. TO bit is set. Oscillator driver is turned off. I/O ports maintain the status they had before SLEEP was executed (driving high, low or highimpedance). For lowest current consumption in this mode, all I/O pins should be either at VDD or VSS, with no external circuitry drawing current from the I/O pin, and all unused peripheral modules should be disabled. Digital I/O pins that are high-impedance inputs should be pulled high or low externally to avoid switching currents caused by floating inputs. The T0CKI input should also be at VDD or VSS for lowest current consumption. The contribution from on-chip pull-ups on PORTA should be considered. 15.6.1 It should be noted that a Reset generated by a WDT time-out does not drive MCLR pin low. WAKE-UP FROM SLEEP The device can wake-up from Sleep through one of the following events: 1. 2. 3. External Reset input on MCLR pin Watchdog Timer Wake-up (if WDT was enabled) Interrupt from RA2/AN2/T0CKI/INT/C1OUT pin, PORTA change or a peripheral interrupt. The first event will cause a device Reset. The two latter events are considered a continuation of program execution. The TO and PD bits in the STATUS register can be used to determine the cause of device Reset. The PD bit, which is set on power-up, is cleared when Sleep is invoked. TO bit is cleared if WDT Wake-up occurred. The following peripheral interrupts can wake the device from Sleep: 1. 2. 3. 4. 5. 6. 7. Note: TMR1 interrupt. Timer1 must be operating as an asynchronous counter. CCP Capture mode interrupt A/D conversion (when A/D clock source is RC) EEPROM write operation completion Comparator output changes state Interrupt-on-change External Interrupt from INT pin If the global interrupts are disabled (GIE is cleared), but any interrupt source has both its interrupt enable bit and the corresponding interrupt flag bits set (including PEIE, where applicable), the device will immediately wake-up from Sleep. The SLEEP instruction is completely executed. The WDT is cleared when the device wakes up from Sleep, regardless of the source of wake-up. 15.6.2 The MCLR pin must be at a logic high level. Note: When the SLEEP instruction is being executed, the next instruction (PC + 1) is pre-fetched. For the device to wake-up through an interrupt event, the corresponding interrupt enable bit (and PEIE bit where applicable) must be set (enabled). Wake-up is regardless of the state of the GIE bit. If the GIE bit is clear (disabled), the device continues execution at the instruction after the SLEEP instruction. If the GIE bit is set (enabled), the device executes the instruction after the SLEEP instruction, then branches to the interrupt address (0004h). In cases where the execution of the instruction following SLEEP is not desirable, the user should have a NOP after the SLEEP instruction. WAKE-UP USING INTERRUPTS When global interrupts are disabled (GIE cleared) and any interrupt source has both its interrupt enable bit and interrupt flag bit set, one of the following will occur: • If the interrupt occurs before the execution of a SLEEP instruction, the SLEEP instruction will complete as a NOP. Therefore, the WDT and WDT prescaler and postscaler (if enabled) will not be cleared, the TO bit will not be set and the PD bit will not be cleared. • If the interrupt occurs during or after the execution of a SLEEP instruction, the device will immediately wake-up from Sleep. The SLEEP instruction will be completely executed before the wake-up. Therefore, the WDT and WDT prescaler and postscaler (if enabled) will be cleared, the TO bit will be set, and the PD bit will be cleared. Even if the flag bits were checked before executing a SLEEP instruction, it may be possible for flag bits to become set before the SLEEP instruction completes. To determine whether a SLEEP instruction executed, test the PD bit. If the PD bit is set, the SLEEP instruction was executed as a NOP. To ensure that the WDT is cleared, a CLRWDT instruction should be executed before a SLEEP instruction. Other peripherals cannot generate interrupts since, during Sleep, no on-chip clocks are present. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 123 PIC16F785 FIGURE 15-9: WAKE-UP FROM SLEEP THROUGH INTERRUPT(1) Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 OSC1 TOST(2) CLKOUT(4) INT pin INTF flag (INTCON<1>) Interrupt Latency (3) GIE bit (INTCON<7>) Processor in Sleep INSTRUCTION FLOW PC PC Instruction Fetched Instruction Executed Note 1: 2: 3: 4: Inst(PC) = Sleep Inst(PC - 1) PC + 1 PC + 2 PC + 2 Inst(PC + 1) Inst(PC + 2) Sleep Inst(PC + 1) PC + 2 Dummy cycle 0004h 0005h Inst(0004h) Inst(0005h) Dummy cycle Inst(0004h) XT, HS or LP Oscillator mode assumed. TOST = 1024TOSC (drawing not to scale). This delay does not apply to EC, RC and INTOSC Oscillator modes or Two-Speed Start-up (see Section 3.6 “Two-Speed Clock Start-up Mode”). GIE = 1 assumed. In this case after wake-up, the processor jumps to 0004h. If GIE = 0, execution will continue in-line. CLKOUT is not available in XT, HS, LP or EC Oscillator modes, but shown here for timing reference. DS41249B-page 124 Preliminary © 2005 Microchip Technology Inc. PIC16F785 15.7 FIGURE 15-10: Code Protection TYPICAL IN-CIRCUIT SERIAL PROGRAMMING CONNECTION If the code protection bit(s) have not been programmed, the on-chip program memory can be read out using ICSP™ for verification purposes. Note: 15.8 The entire data EEPROM and Flash program memory will be erased when the code protection is turned off by performing a bulk erase. See the “PIC16F785/PS200 Memory Programming Specification” (DS41237) for more information. External Connector Signals PIC16F785 +5.0V VDD 0V VSS MCLR/VPP/RA3 CLK RA1 Data I/O RA0 * In-Circuit Serial Programming™ The PIC16F785 microcontrollers can be serially programmed while in the end application circuit. This is simply done with five lines: • • • • • * VPP ID Locations Four memory locations (2000h-2003h) are designated as ID locations where the user can store checksum or other code identification numbers. These locations are not accessible during normal execution, but are readable and writable during Program/Verify. Only the Least Significant 7 bits of the ID locations are used. 15.9 To Normal Connections * * To Normal Connections * Isolation devices (as required) clock data power ground 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. The device is placed into a Program/Verify mode by holding the RA0 and RA1 pins low, while raising the MCLR (VPP) pin from VIL to VIHH. See the “PIC16F785/ PS200 Memory Programming Specification” (DS41237) for more information. RA0 becomes the programming data and RA1 becomes the programming clock. Both RA0 and RA1 are Schmitt Trigger inputs in this mode. After Reset, to place the device into Program/Verify mode, the Program Counter (PC) is at location 00h. A 6-bit command is then supplied to the device. Depending on the command, 14 bits of program data are then supplied to or from the device, depending on whether the command was a load or a read. For complete details of serial programming, please refer to the “PIC16F785/PS200 Memory Programming Specification” (DS41237). A typical In-Circuit Serial Programming connection is shown in Figure 15-10. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 125 PIC16F785 15.10 In-Circuit Debugger In-circuit debugging requires clock, data and MCLR pins. A special 28-pin PIC16F785 ICD device is used with MPLAB® ICD 2 to provide separate clock, data and MCLR pins so that no pins are lost for these functions leaving all 18 of the PIC16F785 I/O pins available to the user during debug operation. This special ICD device is mounted on the top of a header and its signals are routed to the MPLAB ICD 2 connector. On the bottom of the header is a 20-pin socket that plugs into the user’s target via the 20-pin stand-off connector. When the ICD pin on the PIC16F785 ICD device is held low, the In-Circuit Debugger functionality is enabled. This function allows simple debugging functions when used with MPLAB ICD 2. When the microcontroller has this feature enabled, some of the resources are not available for general use. Table 15-9 shows which features are consumed by the background debugger: TABLE 15-9: DEBUGGER RESOURCES Resource Description I/O pins ICDCLK, ICDDATA Stack 1 level Data RAM 65h-70h, F0h Program Memory Address 0h must be NOP 700h-7FFh For more information, see “MPLAB® ICD 2 In-Circuit Debugger User’s Guide” (DS51331), available on Microchip’s web site (www.microchip.com). FIGURE 15-11: 28-PIN ICD PINOUT 28-Pin PDIP In-Circuit Debug Device DS41249B-page 126 1 28 2 3 27 26 4 5 25 24 6 7 8 9 10 11 PIC16F785-ICD SHNTREG ICDMCLR/VPP VDD RA5 RA4 RA3 RC5 RC4 RC3 RC6 RC7 RB7 ICD NC 23 22 21 20 19 18 12 17 13 14 16 15 ICDCLK ICDDATA Vss RA0 RA1 RA2 RC0 RC1 RC2 RB4 RB5 RB6 NC NC Preliminary © 2005 Microchip Technology Inc. PIC16F785 16.0 INSTRUCTION SET SUMMARY The PIC16F785 instruction set is highly orthogonal and is comprised of three basic categories: • Byte-oriented operations • Bit-oriented operations • Literal and control operations For example, a CLRF PORTA instruction will read PORTA, clear all the data bits, then write the result back to PORTA. This example would have the unintended result of clearing the condition that set the RAIF flag. TABLE 16-1: Each PIC16 instruction is a 14-bit word divided into an opcode, which specifies the instruction type and one or more operands, which further specify the operation of the instruction. The format for each of the categories is presented in Figure 16-1, while the various opcode fields are summarized in Table 16-1. Field Table 16-2 lists the instructions recognized by the MPASM TM assembler. A complete description of each instruction is also available in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). For byte-oriented instructions, ‘f’ represents a file register designator and ‘d’ represents a destination designator. The file register designator specifies which file register is to be used by the instruction. The destination designator specifies where the result of the operation is to be placed. If ‘d’ is zero, the result is placed in the W register. If ‘d’ is one, the result is placed in the file register specified in the instruction. Description f Register file address (0x00 to 0x7F) W Working register (accumulator) b Bit address within an 8-bit file register k Literal field, constant data or label x Don't care location (= 0 or 1). The assembler will generate code with x = 0. It is the recommended form of use for compatibility with all Microchip software tools. d Destination select; d = 0: store result in W, d = 1: store result in file register f. Default is d = 1. PC Program Counter TO Time-out bit PD Power-down bit FIGURE 16-1: For bit-oriented instructions, ‘b’ represents a bit field designator, which selects the bit affected by the operation, while ‘f’ represents the address of the file in which the bit is located. One instruction cycle consists of four oscillator periods; for an oscillator frequency of 4 MHz, this gives a normal instruction execution time of 1 μs. All instructions are executed within a single instruction cycle, unless a conditional test is true, or the program counter is changed as a result of an instruction. When this occurs, the execution takes two instruction cycles, with the second cycle executed as a NOP. To maintain upward compatibility with future products, do not use the OPTION and TRIS instructions. Bit-oriented file register operations 13 10 9 7 6 OPCODE b (BIT #) f (FILE #) 0 b = 3-bit bit address f = 7-bit file register address Literal and control operations General 13 8 7 OPCODE 0 k (literal) k = 8-bit immediate value CALL and GOTO instructions only Read-Modify-Write Operations 13 Any instruction that specifies a file register as part of the instruction performs a read-modify-write (RMW) operation. The register is read, the data is modified, and the result is stored according to either the instruction, or the destination designator ‘d’. A read operation is always performed, even if the instruction is a write command. © 2005 Microchip Technology Inc. 0 d = 0 for destination W d = 1 for destination f f = 7-bit file register address All instruction examples use the format ‘0xhh’ to represent a hexadecimal number, where ‘h’ signifies a hexadecimal digit. 16.1 GENERAL FORMAT FOR INSTRUCTIONS Byte-oriented file register operations 13 8 7 6 OPCODE d f (FILE #) For literal and control operations, ‘k’ represents an 8-bit or 11-bit constant, or literal value. Note: OPCODE FIELD DESCRIPTIONS Preliminary 11 OPCODE 10 0 k (literal) k = 11-bit immediate value DS41249B-page 127 PIC16F785 TABLE 16-2: PIC16F785 INSTRUCTION SET Mnemonic, Operands 14-Bit Opcode Description Cycles MSb LSb Status Affected Notes BYTE-ORIENTED FILE REGISTER OPERATIONS ADDWF ANDWF CLRF CLRW COMF DECF DECFSZ INCF INCFSZ IORWF MOVF MOVWF NOP RLF RRF SUBWF SWAPF XORWF f, d f, d f f, d f, d f, d f, d f, d f, d f, d f f, d f, d f, d f, d f, d Add W and f AND W with f Clear f Clear W Complement f Decrement f Decrement f, Skip if 0 Increment f Increment f, Skip if 0 Inclusive OR W with f Move f Move W to f No Operation Rotate Left f through Carry Rotate Right f through Carry Subtract W from f Swap nibbles in f Exclusive OR W with f BCF BSF BTFSC BTFSS f, b f, b f, b f, b Bit Clear f Bit Set f Bit Test f, Skip if Clear Bit Test f, Skip if Set 1 1 1 1 1 1 1(2) 1 1(2) 1 1 1 1 1 1 1 1 1 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 dfff dfff lfff 0xxx dfff dfff dfff dfff dfff dfff dfff lfff 0xx0 dfff dfff dfff dfff dfff ffff ffff ffff xxxx ffff ffff ffff ffff ffff ffff ffff ffff 0000 ffff ffff ffff ffff ffff 00bb 01bb 10bb 11bb bfff bfff bfff bfff ffff ffff ffff ffff 111x 1001 0kkk 0000 1kkk 1000 00xx 0000 01xx 0000 0000 110x 1010 kkkk kkkk kkkk 0110 kkkk kkkk kkkk 0000 kkkk 0000 0110 kkkk kkkk kkkk kkkk kkkk 0100 kkkk kkkk kkkk 1001 kkkk 1000 0011 kkkk kkkk 0111 0101 0001 0001 1001 0011 1011 1010 1111 0100 1000 0000 0000 1101 1100 0010 1110 0110 C,DC,Z Z Z Z Z Z Z Z Z C C C,DC,Z Z 1,2 1,2 2 1,2 1,2 1,2,3 1,2 1,2,3 1,2 1,2 1,2 1,2 1,2 1,2 1,2 BIT-ORIENTED FILE REGISTER OPERATIONS 1 1 1 (2) 1 (2) 01 01 01 01 1,2 1,2 3 3 LITERAL AND CONTROL OPERATIONS ADDLW ANDLW CALL CLRWDT GOTO IORLW MOVLW RETFIE RETLW RETURN SLEEP SUBLW XORLW Note 1: 2: 3: Note: k k k k k k k k k Add literal and W AND literal with W Call subroutine Clear Watchdog Timer Go to address Inclusive OR literal with W Move literal to W Return from interrupt Return with literal in W Return from Subroutine Go into Standby mode Subtract W from literal Exclusive OR literal with W 1 1 2 1 2 1 1 2 2 2 1 1 1 11 11 10 00 10 11 11 00 11 00 00 11 11 C,DC,Z Z TO,PD Z TO,PD C,DC,Z Z When an I/O register is modified as a function of itself (e.g., MOVF PORTA, 1), the value used will be that value present on the pins themselves. For example, if the data latch is ‘1’ for a pin configured as input and is driven low by an external device, the data will be written back with a ‘0’. If this instruction is executed on the TMR0 register (and, where applicable, d = 1), the prescaler will be cleared if assigned to the Timer0 module. If Program Counter (PC) is modified, or a conditional test is true, the instruction requires two cycles. The second cycle is executed as a NOP. Additional information on the mid-range instruction set is available in the “PICmicro® Mid-Range MCU Family Reference Manual” (DS33023). DS41249B-page 128 Preliminary © 2005 Microchip Technology Inc. PIC16F785 16.2 Instruction Descriptions ADDLW Add Literal and W BCF Bit Clear f Syntax: [label] ADDLW Syntax: [label] BCF Operands: 0 ≤ k ≤ 255 Operands: Operation: (W) + k → (W) 0 ≤ f ≤ 127 0≤b≤7 Status Affected: C, DC, Z Operation: 0 → (f<b>) Description: The contents of the W register are added to the eight-bit literal ‘k’ and the result is placed in the W register. Status Affected: None Description: Bit ‘b’ in register ‘f’ is cleared. ADDWF Add W and f BSF Bit Set f Syntax: [label] ADDWF Syntax: [label] BSF Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ f ≤ 127 0≤b≤7 Operation: (W) + (f) → (destination) Operation: 1 → (f<b>) Status Affected: C, DC, Z Status Affected: None Description: Add the contents of the W register with register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. Description: Bit ‘b’ in register ‘f’ is set. ANDLW AND Literal with W BTFSC Bit Test f, Skip if Clear Syntax: [label] ANDLW Syntax: [label] BTFSC f,b Operands: 0 ≤ k ≤ 255 Operands: Operation: (W) .AND. (k) → (W) 0 ≤ f ≤ 127 0≤b≤7 Status Affected: Z Operation: skip if (f<b>) = 0 Description: The contents of W register are AND’ed with the eight-bit literal ‘k’. The result is placed in the W register. Status Affected: None Description: If bit ‘b’ in register ‘f'’ is ‘1’, the next instruction is executed. If bit ‘b’, in register ‘f’, is ‘0’, the next instruction is discarded, and a NOP is executed instead, making this a two-cycle instruction. ANDWF AND W with f BTFSS Bit Test f, Skip if Set Syntax: [label] ANDWF Syntax: [label] BTFSS f,b Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: Operation: (W) .AND. (f) → (destination) 0 ≤ f ≤ 127 0≤b<7 Operation: skip if (f<b>) = 1 Status Affected: Z Status Affected: None Description: AND the W register with register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. Description: If bit ‘b’ in register ‘f’ is ‘0’, the next instruction is executed. If bit ‘b’ is ‘1’, then the next instruction is discarded and a NOP is executed instead, making this a two-cycle instruction. © 2005 Microchip Technology Inc. k f,d k f,d Preliminary f,b f,b DS41249B-page 129 PIC16F785 CALL Call Subroutine COMF Complement f Syntax: [ label ] CALL k Syntax: [ label ] COMF Operands: 0 ≤ k ≤ 2047 Operands: Operation: (PC)+ 1→ TOS, k → PC<10:0>, (PCLATH<4:3>) → PC<12:11> 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) → (destination) Status Affected: Z Status Affected: None Description: Description: Call Subroutine. First, return address (PC + 1) is pushed onto the stack. The eleven-bit immediate address is loaded into PC bits <10:0>. The upper bits of the PC are loaded from PCLATH. CALL is a two-cycle instruction. 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’. CLRF Clear f DECF Decrement f Syntax: [label] CLRF Syntax: [label] DECF f,d Operands: 0 ≤ f ≤ 127 Operands: Operation: 00h → (f) 1→Z 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) - 1 → (destination) Status Affected: Z Status Affected: Z Description: The contents of register ‘f’ are cleared and the Z bit is set. Description: Decrement register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. CLRW Clear W Syntax: [ label ] CLRW DECFSZ Decrement f, Skip if 0 Operands: None Syntax: [ label ] DECFSZ f,d Operation: 00h → (W) 1→Z Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Status Affected: Z Operation: Description: W register is cleared. Zero bit (Z) is set. (f) - 1 → (destination); skip if result = 0 Status Affected: None Description: The contents of register ‘f’ are decremented. If ‘d’ is ‘0’, the result is placed in the W register. If ‘d’ is ‘1’, the result is placed back in register ‘f’. If the result is ‘1’, the next instruction is executed. If the result is ‘0’, then a NOP is executed instead, making it a two-cycle instruction. f CLRWDT Clear Watchdog Timer Syntax: [ label ] CLRWDT Operands: None Operation: 00h → WDT 0 → WDT prescaler, 1 → TO 1 → PD Status Affected: TO, PD Description: CLRWDT instruction resets the Watchdog Timer. It also resets the prescaler of the WDT. Status bits TO and PD are set. DS41249B-page 130 Preliminary f,d © 2005 Microchip Technology Inc. PIC16F785 GOTO Unconditional Branch IORLW Inclusive OR Literal with W Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ k ≤ 2047 Operands: 0 ≤ k ≤ 255 Operation: k → PC<10:0> PCLATH<4:3> → PC<12:11> Operation: (W) .OR. k → (W) Status Affected: Z Status Affected: None Description: Description: GOTO is an unconditional branch. The eleven-bit immediate value is loaded into PC bits <10:0>. The upper bits of PC are loaded from PCLATH<4:3>. GOTO is a twocycle instruction. The contents of the W register are OR’ed with the eight-bit literal ‘k’. The result is placed in the W register. INCF Increment f IORWF Inclusive OR W with f Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) + 1 → (destination) Operation: (W) .OR. (f) → (destination) Status Affected: Z Status Affected: Z Description: The contents of register ‘f’ are incremented. If ‘d’ is ‘0’, the result is placed in the W register. If ‘d’ is ‘1’, the result is placed back in register ‘f’. Description: Inclusive OR the W register with register ‘f’. If ‘d’ is ‘0’, the result is placed in the W register. If ‘d’ is ‘1’, the result is placed back in register ‘f’. INCFSZ Increment f, Skip if 0 MOVF Move f Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) + 1 → (destination), skip if result = 0 Operation: (f) → (dest) Status Affected: Z Status Affected: None Description: The contents of register ‘f’ are incremented. If ‘d’ is ‘0’, the result is placed in the W register. If ‘d’ is ‘1’, the result is placed back in register ‘f’. If the result is ‘1’, the next instruction is executed. If the result is ‘0’, a NOP is executed instead, making it a two-cycle instruction. GOTO k INCF f,d INCFSZ f,d Encoding: Description: 00 IORWF f,d MOVF f,d 1000 dfff ffff The contents of register ‘f’ is moved to a destination dependent upon the status of ‘d’. If ‘d’ = 0, destination is W register. If ‘d’ = 1, the destination is file register ‘f’ itself. ‘d’ = 1 is useful to test a file register since status flag Z is affected. Words: 1 Cycles: 1 Example: IORLW k MOVF FSR, 0 After Instruction W = register Z = © 2005 Microchip Technology Inc. Preliminary value in FSR 1 DS41249B-page 131 PIC16F785 MOVLW Move Literal to W NOP No Operation Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ k ≤ 255 Operands: None Operation: k → (W) Operation: No operation None Status Affected: None Status Affected: Encoding: Description: MOVLW k 11 00xx kkkk kkkk The eight-bit literal ‘k’ is loaded into W register. The “don’t cares” will assemble as 0’s. Words: 1 Cycles: 1 Example: Encoding: Description: 00 0000 0xx0 0000 No operation. Words: 1 Cycles: 1 Example: MOVLW NOP NOP 0x5A After Instruction W = 0x5A RETFIE Return from Interrupt Syntax: [ label ] 0 ≤ f ≤ 127 Operands: None Operation: (W) → (f) Operation: Status Affected: None TOS → PC, 1 → GIE Status Affected: None MOVWF Move W to f Syntax: [ label ] Operands: Encoding: Description: 00 0000 f 1fff ffff Move data from W register to register ‘f’. Words: 1 Cycles: 1 Example: MOVWF MOVWF Encoding: After Instruction OPTION = W = 0x4F 0x4F 0000 1001 Return from Interrupt. Stack is POPed and Top-of-Stack (TOS) is loaded in the PC. Interrupts are enabled by setting Global Interrupt Enable bit, GIE (INTCON<7>). This is a two-cycle instruction. Words: 1 Cycles: 2 Before Instruction 0xFF 0x4F 0000 Description: OPTION OPTION = W = 00 RETFIE Example: RETFIE After Interrupt PC = GIE = DS41249B-page 132 Preliminary TOS 1 © 2005 Microchip Technology Inc. PIC16F785 RETLW Return with Literal in W RLF Rotate Left f through Carry Syntax: [ label ] Syntax: [ label ] Operands: 0 ≤ k ≤ 255 Operands: Operation: k → (W); TOS → PC 0 ≤ f ≤ 127 d ∈ [0,1] Operation: See description below None Status Affected: C Status Affected: Encoding: RETLW k 11 01xx kkkk kkkk Description: The W register is loaded with the eight-bit literal ‘k’. The program counter is loaded from the top of the stack (the return address). This is a two-cycle instruction. Words: 1 Cycles: 2 Example: CALL TABLE;W contains table ;offset value • ;W now has table value • • ADDWF PC ;W = offset RETLW k1 ;Begin table RETLW k2 ; • • • RETLW kn ; End of table TABLE Encoding: Description: RLF 00 1101 dfff 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 the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. C Words: 1 Cycles: 1 Example: f,d RLF Register f REG1,0 Before Instruction REG1 C = = 1110 0110 0 = = = 1110 0110 1100 1100 1 After Instruction REG1 W C Before Instruction W = 0x07 After Instruction W RETURN = value of k8 Return from Subroutine Syntax: [ label ] Operands: None RETURN Operation: TOS → PC Status Affected: None Description: Return from subroutine. The stack is POPed and the top of the stack (TOS) is loaded into the program counter. This is a two-cycle instruction. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 133 PIC16F785 RRF Rotate Right f through Carry SUBLW Subtract W from Literal Syntax: [ label ] Syntax: [label] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ k ≤ 255 Operation: k - (W) → (W) Operation: See description below C, DC, Z Status Affected: C Status Affected: Encoding: 00 Encoding: 11 Description: The contents of register ‘f’ are rotated one bit to the right through the Carry Flag. If ‘d’ is ‘0’, the result is placed in the W register. If ‘d’ is ‘1’ the result is placed back in register ‘f’. Description: The W register is subtracted (2’s complement method) from the eightbit literal ‘k’. The result is placed in the W register. 1100 C Words: 1 Cycles: 1 Example: RRF RRF f,d dfff ffff REGISTER F SUBLW k 110x Words: 1 Cycles: 1 Example 1: SUBLW kkkk kkkk 0x02 Before Instruction W = 1 C = ? REG1, 0 After Instruction Before Instruction REG1 = 1110 0110 C = 0 After Instruction REG1 = 1110 0110 W = 0111 0011 C = 0 W = 1 C = 1; result is positive Example 2: Before Instruction W = 2 C = ? After Instruction SLEEP Go into Standby mode Syntax: [label] Operands: None Operation: 00h → WDT, 0 → WDT prescaler, 1 → TO, 0 → PD W = 0 C = 1; result is zero Example 3: SLEEP W = C = W = C = TO, PD Encoding: 00 Description: The power-down Status bit, PD is cleared. Time out Status bit, TO is set. Watchdog Timer and its prescaler are cleared. The processor is put into Sleep mode with the oscillator stopped. Words: 1 Cycles: 1 Example: SLEEP DS41249B-page 134 0110 3 ? After Instruction Status Affected: 0000 Before Instruction 0xFF 0; result is negative 0011 Preliminary © 2005 Microchip Technology Inc. PIC16F785 SUBWF Subtract W from f SWAPF Swap Nibbles in f Syntax: [label] Syntax: [ label ] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (f) - (W) → (dest) Operation: Status Affected: C, DC, Z (f<3:0>) → (dest<7:4>), (f<7:4>) → (dest<3:0>) Status Affected: None Encoding: 00 Encoding: 00 Description: Subtract (2’s complement method) W register from register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’, the result is stored back in register ‘f’. Description: The upper and lower nibbles of register ‘f’ are exchanged. If ‘d’ is ‘0’, the result is placed in W register. If ‘d’ is ‘1’, the result is placed in register ‘f’. Words: 1 Words: 1 Cycles: 1 Cycles: 1 Example 1: SUBWF Example: SWAPF SUBWF f,d 0010 dfff ffff REG1, 1 Before Instruction Example 2: 1 2 1; result is positive 0 1 After Instruction Example 3: TRIS REG1 = 1 W = 2 C = ? [ label ] TRIS Operands: 5≤f≤6 Operation: (W) → TRIS register f; Status Affected: None Encoding: 00 Description: The instruction is supported for code compatibility with the PIC16C5X products. Since TRIS registers are readable and writable, the user can directly address them. Words: 1 Cycles: 1 © 2005 Microchip Technology Inc. 0000 f 0110 0fff Example After Instruction = = = = Load TRIS Register Syntax: 0 2 1; result is zero DC = 1 Before Instruction REG1 W C Z REG1, 0 REG1 = 0xA5 W = 0x5A REG1 = 2 W = 2 C = ? = = = = ffff After Instruction Before Instruction REG1 W C Z dfff REG1 = 0xA5 After Instruction = = = = = 1110 Before Instruction REG1 = 3 W = 2 C = ? REG1 W C Z DC SWAPF f,d 0xFF 2 0; result is negative DC = 0 Preliminary To maintain upward compatibility with future PICmicro® products, do not use this instruction. DS41249B-page 135 PIC16F785 XORLW Exclusive OR Literal with W XORWF Exclusive OR W with f Syntax: [label] Syntax: [ label ] Operands: 0 ≤ k ≤ 255 Operands: 0 ≤ f ≤ 127 d ∈ [0,1] Operation: (W) .XOR. (f) → (dest) Status Affected: Z Encoding: 00 Description: Exclusive OR the contents of the W register with register ‘f’. If ‘d’ is ‘0’, the result is stored in the W register. If ‘d’ is ‘1’ the result is stored back in register ‘f’. Words: 1 Cycles: 1 Example: XORWF XORLW k Operation: (W) .XOR. k → (W) Status Affected: Z Encoding: 11 Description: The contents of the W register are XOR’ed with the eight-bit literal ‘k’. The result is placed in the W register. 1010 Words: 1 Cycles: 1 Example: XORLW kkkk 0xAF Before Instruction W = 0xB5 kkkk XORWF 0110 f,d dfff ffff REG1, 1 Before Instruction After Instruction REG1 = 0xAF W = 0xB5 W = 0x1A After Instruction REG1 = 0x1A W = 0xB5 DS41249B-page 136 Preliminary © 2005 Microchip Technology Inc. PIC16F785 17.0 DEVELOPMENT SUPPORT 17.1 The PICmicro® microcontrollers are supported with a full range of hardware and software development tools: • Integrated Development Environment - MPLAB® IDE Software • Assemblers/Compilers/Linkers - MPASMTM Assembler - MPLAB C17 and MPLAB C18 C Compilers - MPLINKTM Object Linker/ MPLIBTM Object Librarian - MPLAB C30 C Compiler - MPLAB ASM30 Assembler/Linker/Library • Simulators - MPLAB SIM Software Simulator - MPLAB dsPIC30 Software Simulator • Emulators - MPLAB ICE 2000 In-Circuit Emulator - MPLAB ICE 4000 In-Circuit Emulator • In-Circuit Debugger - MPLAB ICD 2 • Device Programmers - PRO MATE® II Universal Device Programmer - PICSTART® Plus Development Programmer - MPLAB PM3 Device Programmer • Low-Cost Demonstration Boards - PICDEMTM 1 Demonstration Board - PICDEM.netTM Demonstration Board - PICDEM 2 Plus Demonstration Board - PICDEM 3 Demonstration Board - PICDEM 4 Demonstration Board - PICDEM 17 Demonstration Board - PICDEM 18R Demonstration Board - PICDEM LIN Demonstration Board - PICDEM USB Demonstration Board • Evaluation Kits - KEELOQ® Evaluation and Programming Tools - PICDEM MSC - microID® Developer Kits - CAN - PowerSmart® Developer Kits - Analog 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® based application that contains: • An interface to 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 • Mouse over variable inspection • Extensive on-line help The MPLAB IDE allows you to: • Edit your source files (either assembly or C) • One touch assemble (or compile) and download to PICmicro 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 increasing flexibility and power. 17.2 MPASM Assembler The MPASM assembler is a full-featured, universal macro assembler for all PICmicro MCUs. The MPASM assembler generates relocatable object files for the MPLINK object linker, Intel® standard HEX files, MAP files to detail memory usage and symbol reference, absolute LST files that contain source lines and generated machine code and COFF files for debugging. The MPASM assembler features include: • Integration into MPLAB IDE projects • User defined macros to streamline assembly code • Conditional assembly for multi-purpose source files • Directives that allow complete control over the assembly process © 2005 Microchip Technology Inc. Preliminary DS41249B-page 137 PIC16F785 17.3 MPLAB C17 and MPLAB C18 C Compilers 17.6 The MPLAB C17 and MPLAB C18 Code Development Systems are complete ANSI C compilers for Microchip’s PIC17CXXX and PIC18CXXX family of microcontrollers. 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. 17.4 MPLINK Object Linker/ MPLIB Object Librarian The MPLINK object linker combines relocatable objects created by the MPASM assembler and the MPLAB C17 and MPLAB C18 C compilers. It can link relocatable objects from precompiled libraries, using directives from a linker script. The MPLIB object librarian manages the creation and modification of library files of precompiled code. When a routine from a library is called from a source file, only the modules that contain that routine will be linked in with the application. This allows large libraries to be used efficiently in many different applications. The object linker/library features include: • Efficient linking of single libraries instead of many smaller files • Enhanced code maintainability by grouping related modules together • Flexible creation of libraries with easy module listing, replacement, deletion and extraction 17.5 MPLAB C30 C Compiler MPLAB C30 is distributed with a complete ANSI C standard library. All library functions have been validated and conform to the ANSI C library standard. The library includes functions for string manipulation, dynamic memory allocation, data conversion, timekeeping and math functions (trigonometric, exponential and hyperbolic). The compiler provides symbolic information for high-level source debugging with the MPLAB IDE. DS41249B-page 138 MPLAB ASM30 assembler produces relocatable machine code from symbolic assembly language for dsPIC30F devices. MPLAB C30 compiler uses the assembler to produce it’s 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 17.7 MPLAB SIM Software Simulator The MPLAB SIM software simulator allows code development in a PC hosted environment by simulating the PICmicro series microcontrollers on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any pin. The execution can be performed in Single-Step, Execute Until Break or Trace mode. The MPLAB SIM simulator fully supports symbolic debugging using the MPLAB C17 and MPLAB C18 C Compilers, as well as the MPASM assembler. The software simulator offers the flexibility to develop and debug code outside of the laboratory environment, making it an excellent, economical software development tool. 17.8 The MPLAB C30 C compiler is a full-featured, ANSI compliant, optimizing compiler that translates standard ANSI C programs into dsPIC30F assembly language source. The compiler also supports many command line options and language extensions to take full advantage of the dsPIC30F device hardware capabilities and afford fine control of the compiler code generator. MPLAB ASM30 Assembler, Linker and Librarian MPLAB SIM30 Software Simulator The MPLAB SIM30 software simulator allows code development in a PC hosted environment by simulating the dsPIC30F series microcontrollers on an instruction level. On any given instruction, the data areas can be examined or modified and stimuli can be applied from a file, or user defined key press, to any of the pins. The MPLAB SIM30 simulator fully supports symbolic debugging using the MPLAB C30 C Compiler and MPLAB ASM30 assembler. The simulator runs in either a Command Line mode for automated tasks, or from MPLAB IDE. This high-speed simulator is designed to debug, analyze and optimize time intensive DSP routines. Preliminary © 2005 Microchip Technology Inc. PIC16F785 17.9 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator 17.11 MPLAB ICD 2 In-Circuit Debugger The MPLAB ICE 2000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for PICmicro 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 universal architecture of the MPLAB ICE in-circuit emulator allows expansion to support new PICmicro microcontrollers. The MPLAB ICE 2000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. The PC platform and Microsoft® Windows 32-bit operating system were chosen to best make these features available in a simple, unified application. 17.10 MPLAB ICE 4000 High-Performance Universal In-Circuit Emulator The MPLAB ICE 4000 universal in-circuit emulator is intended to provide the product development engineer with a complete microcontroller design tool set for highend PICmicro microcontrollers. Software control of the MPLAB ICE in-circuit emulator is provided by the MPLAB Integrated Development Environment, which allows editing, building, downloading and source debugging from a single environment. The MPLAB ICD 4000 is a premium emulator system, providing the features of MPLAB ICE 2000, but with increased emulation memory and high-speed performance for dsPIC30F and PIC18XXXX devices. Its advanced emulator features include complex triggering and timing, up to 2 Mb of emulation memory and the ability to view variables in real-time. The MPLAB ICE 4000 in-circuit emulator system has been designed as a real-time emulation system with advanced features that are typically found on more expensive development tools. The PC platform and Microsoft Windows 32-bit operating system were chosen to best make these features available in a simple, unified application. © 2005 Microchip Technology Inc. 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 PICmicro MCUs and can be used to develop for these and other PICmicro microcontrollers. The MPLAB ICD 2 utilizes the in-circuit debugging capability built into the Flash devices. This feature, along with Microchip’s In-Circuit Serial ProgrammingTM (ICSPTM) protocol, offers cost effective in-circuit Flash debugging from the graphical user interface of the MPLAB Integrated Development Environment. This enables a designer to develop and debug source code by setting breakpoints, single-stepping and watching variables, 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 PICmicro devices. 17.12 PRO MATE II Universal Device Programmer The PRO MATE II is a universal, CE compliant device programmer with programmable voltage verification at VDDMIN and VDDMAX for maximum reliability. It features an LCD display for instructions and error messages and a modular detachable socket assembly to support various package types. In Stand-Alone mode, the PRO MATE II device programmer can read, verify and program PICmicro devices without a PC connection. It can also set code protection in this mode. 17.13 MPLAB PM3 Device Programmer The MPLAB PM3 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 ICSP™ cable assembly is included as a standard item. In StandAlone mode, the MPLAB PM3 device programmer can read, verify and program PICmicro devices without a PC connection. It can also set code protection in this mode. MPLAB PM3 connects to the host PC via an RS232 or USB cable. 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. Preliminary DS41249B-page 139 PIC16F785 17.14 PICSTART Plus Development Programmer 17.17 PICDEM 2 Plus Demonstration Board 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 PICmicro devices 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. The PICDEM 2 Plus demonstration board supports many 18, 28 and 40-pin microcontrollers, including PIC16F87X and PIC18FXX2 devices. All the necessary hardware and software is included to run the demonstration programs. The sample microcontrollers provided with the PICDEM 2 demonstration board can be programmed with a PRO MATE II device programmer, PICSTART Plus development programmer, or MPLAB ICD 2 with a Universal Programmer Adapter. The MPLAB ICD 2 and MPLAB ICE in-circuit emulators may also be used with the PICDEM 2 demonstration board to test firmware. A prototype area extends the circuitry for additional application components. Some of the features include an RS-232 interface, a 2 x 16 LCD display, a piezo speaker, an on-board temperature sensor, four LEDs and sample PIC18F452 and PIC16F877 Flash microcontrollers. 17.15 PICDEM 1 PICmicro Demonstration Board The PICDEM 1 demonstration board demonstrates the capabilities of the PIC16C5X (PIC16C54 to PIC16C58A), PIC16C61, PIC16C62X, PIC16C71, PIC16C8X, PIC17C42, PIC17C43 and PIC17C44. All necessary hardware and software is included to run basic demo programs. The sample microcontrollers provided with the PICDEM 1 demonstration board can be programmed with a PRO MATE II device programmer or a PICSTART Plus development programmer. The PICDEM 1 demonstration board can be connected to the MPLAB ICE in-circuit emulator for testing. A prototype area extends the circuitry for additional application components. Features include an RS-232 interface, a potentiometer for simulated analog input, push button switches and eight LEDs. 17.16 PICDEM.net Internet/Ethernet Demonstration Board The PICDEM.net demonstration board is an Internet/ Ethernet demonstration board using the PIC18F452 microcontroller and TCP/IP firmware. The board supports any 40-pin DIP device that conforms to the standard pinout used by the PIC16F877 or PIC18C452. This kit features a user friendly TCP/IP stack, web server with HTML, a 24L256 Serial EEPROM for Xmodem download to web pages into Serial EEPROM, ICSP/MPLAB ICD 2 interface connector, an Ethernet interface, RS-232 interface and a 16 x 2 LCD display. Also included is the book and CD-ROM “TCP/IP Lean, Web Servers for Embedded Systems,” by Jeremy Bentham DS41249B-page 140 17.18 PICDEM 3 PIC16C92X Demonstration Board The PICDEM 3 demonstration board supports the PIC16C923 and PIC16C924 in the PLCC package. All the necessary hardware and software is included to run the demonstration programs. 17.19 PICDEM 4 8/14/18-Pin Demonstration Board The PICDEM 4 can be used to demonstrate the capabilities of the 8, 14 and 18-pin PIC16XXXX and PIC18XXXX MCUs, including the PIC16F818/819, PIC16F87/88, PIC16F62XA and the PIC18F1320 family of microcontrollers. PICDEM 4 is intended to showcase the many features of these low pin count parts, including LIN and Motor Control using ECCP. Special provisions are made for low-power operation with the supercapacitor circuit and jumpers allow onboard hardware to be disabled to eliminate current draw in this mode. Included on the demo board are provisions for Crystal, RC or Canned Oscillator modes, a five volt regulator for use with a nine volt wall adapter or battery, DB-9 RS-232 interface, ICD connector for programming via ICSP and development with MPLAB ICD 2, 2 x 16 liquid crystal display, PCB footprints for H-Bridge motor driver, LIN transceiver and EEPROM. Also included are: header for expansion, eight LEDs, four potentiometers, three push buttons and a prototyping area. Included with the kit is a PIC16F627A and a PIC18F1320. Tutorial firmware is included along with the User’s Guide. Preliminary © 2005 Microchip Technology Inc. PIC16F785 17.20 PICDEM 17 Demonstration Board The PICDEM 17 demonstration board is an evaluation board that demonstrates the capabilities of several Microchip microcontrollers, including PIC17C752, PIC17C756A, PIC17C762 and PIC17C766. A programmed sample is included. The PRO MATE II device programmer, or the PICSTART Plus development programmer, can be used to reprogram the device for user tailored application development. The PICDEM 17 demonstration board supports program download and execution from external on-board Flash memory. A generous prototype area is available for user hardware expansion. 17.21 PICDEM 18R PIC18C601/801 Demonstration Board The PICDEM 18R demonstration board serves to assist development of the PIC18C601/801 family of Microchip microcontrollers. It provides hardware implementation of both 8-bit Multiplexed/Demultiplexed and 16-bit Memory modes. The board includes 2 Mb external Flash memory and 128 Kb SRAM memory, as well as serial EEPROM, allowing access to the wide range of memory types supported by the PIC18C601/801. 17.22 PICDEM LIN PIC16C43X Demonstration Board The powerful LIN hardware and software kit includes a series of boards and three PICmicro microcontrollers. The small footprint PIC16C432 and PIC16C433 are used as slaves in the LIN communication and feature on-board LIN transceivers. A PIC16F874 Flash microcontroller serves as the master. All three microcontrollers are programmed with firmware to provide LIN bus communication. 17.24 PICDEM USB PIC16C7X5 Demonstration Board The PICDEM USB Demonstration Board shows off the capabilities of the PIC16C745 and PIC16C765 USB microcontrollers. This board provides the basis for future USB products. 17.25 Evaluation and Programming Tools In addition to the PICDEM series of circuits, Microchip has a line of evaluation kits and demonstration software for these products. • KEELOQ evaluation and programming tools for Microchip’s HCS Secure Data Products • CAN developers kit for automotive network applications • Analog design boards and filter design software • PowerSmart battery charging evaluation/ calibration kits • IrDA® development kit • microID development and rfLabTM development software • SEEVAL® designer kit for memory evaluation and endurance calculations • PICDEM MSC demo boards for Switching mode power supply, high-power IR driver, delta sigma ADC and flow rate sensor Check the Microchip web page and the latest Product Selector Guide for the complete list of demonstration and evaluation kits. 17.23 PICkitTM 1 Flash Starter Kit A complete “development system in a box”, the PICkit™ Flash Starter Kit includes a convenient multi-section board for programming, evaluation and development of 8/14-pin Flash PIC® microcontrollers. Powered via USB, the board operates under a simple Windows GUI. The PICkit 1 Starter Kit includes the User’s Guide (on CD ROM), PICkit 1 tutorial software and code for various applications. Also included are MPLAB® IDE (Integrated Development Environment) software, software and hardware “Tips 'n Tricks for 8-pin Flash PIC® Microcontrollers” Handbook and a USB interface cable. Supports all current 8/14-pin Flash PIC microcontrollers, as well as many future planned devices. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 141 PIC16F785 NOTES: DS41249B-page 142 Preliminary © 2005 Microchip Technology Inc. PIC16F785 18.0 ELECTRICAL SPECIFICATIONS Absolute Maximum Ratings(†) Ambient temperature under bias........................................................................................................... -40 to +125°C Storage temperature ........................................................................................................................ -65°C to +150°C Voltage on VDD with respect to VSS ...................................................................................................... -0.3 to +6.5V Voltage on MCLR with respect to Vss ..................................................................................................-0.3 to +13.5V Voltage on all other pins with respect to VSS ........................................................................... -0.3V to (VDD + 0.3V) Total power dissipation(1) (PDIP and SOIC)................................................................................................... 800 mW Total power dissipation(1) (SSOP) .................................................................................................................. 600 mW 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 PORTA, PORTB, and PORTC (combined) ........................................................... 200 mA Maximum current sourced PORTA, PORTB, and PORTC (combined)........................................................... 200 mA Note 1: Power dissipation is calculated as follows: PDIS = VDD x {IDD – ∑ IOH} + ∑ {(VDD – VOH) x IOH} + ∑(VOl x IOL). † NOTICE: Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. Note: Voltage spikes below VSS at the MCLR pin, inducing currents greater than 80 mA, may cause latch-up. Thus, a series resistor of 50-100Ω should be used when applying a “low” level to the MCLR pin, rather than pulling this pin directly to VSS. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 143 PIC16F785 FIGURE 18-1: PIC16F785 WITH ANALOG DISABLED VOLTAGE-FREQUENCY GRAPH, -40°C ≤ TA ≤ +125°C 5.5 5.0 4.5 VDD (Volts) 4.0 3.5 3.0 2.5 2.0 0 4 8 10 12 16 20 Frequency (MHz) Note: The shaded region indicates the permissible combinations of voltage and frequency. DS41249B-page 144 Preliminary © 2005 Microchip Technology Inc. PIC16F785 18.1 DC Characteristics: PIC16F785-I (Industrial), PIC16F785-E (Extended) DC CHARACTERISTICS Param No. Sym VDD Characteristic Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial -40°C ≤ TA ≤ +125°C for extended Min Typ† Max Units 2.0 2.2 2.5 3.0 4.5 — — — — — 5.5 5.5 5.5 5.5 5.5 V V V V V FOSC ≤ 4 MHz: PIC16F785with A/D off PIC16F785 with A/D on, 0°C to +125°C PIC16F785 with A/D on, -40°C to +125°C 4 MHz ≤ FOSC ≤ 10 MHz 10 MHz ≤ FOSC ≤ 20 MHz 1.5* — — V Device in Sleep mode — 1.8 — V See Section 15.2.1 “Power-On Reset” for details. — 1.0 — V See Section 15.2.1 “Power-On Reset” for details. 0.05* — — — 2.1 — Supply Voltage D001 D001A D001B D001C D001D D002 VDR RAM Data Retention Voltage(1) D003 VPOR VDD voltage above which the internal POR releases D003A VPARM VDD voltage below which the internal POR rearms D004 SVDD VDD Rise Rate to ensure internal Power-on Reset signal D005 VBOR Brown-out Reset Conditions V/ms See Section 15.2.1 “Power-On Reset” for details. V * These parameters are characterized but not tested. † Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: This is the limit to which VDD can be lowered in Sleep mode without losing RAM data. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 145 PIC16F785 DC Characteristics: PIC16F785-I (Industrial)(1,2) 18.2 DC CHARACTERISTICS Param No. D010 Conditions Device Characteristics D011 D012 D013 D014 D015 D016 D017 D018 Note 1: 2: 3: 4: Min Typ† Max Units VDD Supply Current (IDD) Legend: † Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial — 9 TBD μA 2.0 — 17 TBD μA 3.0 — 33 TBD μA 5.0 — 110 TBD μA 2.0 — 190 TBD μA 3.0 — 330 TBD μA 5.0 — 220 TBD μA 2.0 — 300 TBD μA 3.0 — 540 TBD μA 5.0 — 70 TBD μA 2.0 — 140 TBD μA 3.0 — 260 TBD μA 5.0 — 180 TBD μA 2.0 — 320 TBD μA 3.0 — 580 TBD μA 5.0 — 9 TBD μA 2.0 — 18 TBD μA 3.0 — 35 TBD mA 5.0 — 340 TBD μA 2.0 — 500 TBD μA 3.0 — 0.8 TBD mA 5.0 — 180 TBD μA 2.0 — 320 TBD μA 3.0 — 580 TBD μA 5.0 — 2.8 TBD mA 4.5 — 3.3 TBD mA 5.0 Note FOSC = 32 kHz LP Oscillator mode FOSC = 1 MHz XT Oscillator mode FOSC = 4 MHz XT Oscillator mode FOSC = 1 MHz EC Oscillator mode FOSC = 4 MHz EC Oscillator mode FOSC = 31 kHz INTRC mode FOSC = 4 MHz INTOSC mode FOSC = 4 MHz EXTRC mode FOSC = 20 MHz HS Oscillator mode TBD = To Be Determined. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square wave, from rail-torail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled. The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 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. When A/D is off, it will not consume any current other than leakage current. the power-down current spec includes any such leakage from the A/D module. DS41249B-page 146 Preliminary © 2005 Microchip Technology Inc. PIC16F785 DC Characteristics: PIC16F785-I (Industrial)(1,2) (Continued) 18.2 DC CHARACTERISTICS Param No. D020 Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial Conditions Device Characteristics Power-down Base Current (IPD)(4) D021 Min Typ† Max Units VDD Note — 25 TBD nA 2.0 — 45 TBD nA 3.0 WDT, BOR, Comparators, VREF, T1OSC, Op Amps and VR disabled — 85 TBD nA 5.0 — 0.3 TBD μA 2.0 — 1.2 TBD μA 3.0 — 2.2 TBD μA 5.0 D022 — 50 TBD μA 3.0 — 100 TBD μA 5.0 D023 — 150 TBD μA 2.0 — 170 TBD μA 3.0 — 200 TBD μA 5.0 — 3.3 TBD μA 2.0 — 6.1 TBD μA 3.0 D023A D024 D024A D025 D026 D027 D028 Legend: † Note 1: 2: 3: 4: WDT Current(3) BOR Current(3) Comparator Current(3) CxSP = 1 Comparator Current(3) CxSP = 0 — 35 TBD μA 5.0 — 58 TBD μA 2.0 — 85 TBD μA 3.0 — 104 TBD μA 5.0 — 35 TBD μA 2.0 — 45 TBD μA 3.0 — 80 TBD μA 5.0 — 1.8 TBD μA 2.0 — 2.0 TBD μA 3.0 — 3.2 TBD μA 5.0 — 1.2 TBD nA 3.0 — 2.2 TBD nA 5.0 A/D Current(3) (not converting) — 10 TBD μA 2.0 VR Current(3) 3.0 — 11 TBD μA — 12 TBD μA 5.0 — 150 TBD μA 3.0 — 250 TBD μA 5.0 CVREF Current(3) Low Range CVREF Current(3) High Range (VRR = 0) T1 OSC Current(3) Op Amp Current(3) TBD = To Be Determined. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square wave, from rail-torail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled. The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 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. When A/D is off, it will not consume any current other than leakage current. the power-down current spec includes any such leakage from the A/D module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 147 PIC16F785 DC Characteristics: PIC16F785-E (Extended)(1,2) 18.3 DC CHARACTERISTICS Param No. D010E Conditions Device Characteristics D011E D012E D013E D014E D015E D016E D017E D018E Note 1: 2: 3: 4: Min Typ† Max Units VDD Supply Current (IDD) Legend: † Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C for extended — 9 TBD μA 2.0 — 17 TBD μA 3.0 — 33 TBD μA 5.0 — 110 TBD μA 2.0 — 190 TBD μA 3.0 — 330 TBD μA 5.0 — 220 TBD μA 2.0 — 300 TBD μA 3.0 — 540 TBD μA 5.0 — 70 TBD μA 2.0 — 140 TBD μA 3.0 — 260 TBD μA 5.0 — 180 TBD μA 2.0 — 320 TBD μA 3.0 — 580 TBD μA 5.0 — 9 TBD μA 2.0 — 18 TBD μA 3.0 — 35 TBD mA 5.0 — 340 TBD μA 2.0 — 500 TBD μA 3.0 — 0.8 TBD mA 5.0 — 180 TBD μA 2.0 — 320 TBD μA 3.0 — 580 TBD μA 5.0 — 2.8 TBD mA 4.5 — 3.3 TBD mA 5.0 Note FOSC = 32 kHz LP Oscillator mode FOSC = 1 MHz XT Oscillator mode FOSC = 4 MHz XT Oscillator mode FOSC = 1 MHz EC Oscillator mode FOSC = 4 MHz EC Oscillator mode FOSC = 31 kHz INTRC mode FOSC = 4 MHz INTOSC mode FOSC = 4 MHz EXTRC mode FOSC = 20 MHz HS Oscillator mode TBD = To Be Determined Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square wave, from rail to rail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled. The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 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. When A/D is off, it will not consume any current other than leakage current. The power-down current spec includes any such leakage from the A/D module. DS41249B-page 148 Preliminary © 2005 Microchip Technology Inc. PIC16F785 DC Characteristics: PIC16F785-E (Extended)(1,2) (Continued) 18.3 DC CHARACTERISTICS Param No. D020E Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C for extended Conditions Device Characteristics Power-down Base Current (IPD)(4) D021E Min Typ† Max Units VDD Note — 25 TBD nA 2.0 — 45 TBD nA 3.0 WDT, BOR, Comparators, VREF, T1OSC, Op Amps and VR disabled — 85 TBD nA 5.0 — 0.3 TBD μA 2.0 — 1.2 TBD μA 3.0 — 2.2 TBD μA 5.0 D022E — 50 TBD μA 3.0 — 100 TBD μA 5.0 D023E — 50 TBD μA 2.0 — 170 TBD μA 3.0 — 200 TBD μA 5.0 — 3.3 TBD μA 2.0 — 6.1 TBD μA 3.0 D023E D024E D024E D025E D026E D027E D028E Legend: † Note 1: 2: 3: 4: WDT Current(3) BOR Current(3) Comparator Current(3) CxSP = 1 Comparator Current(3) CxSP = 0 — 35 TBD μA 5.0 — 58 TBD μA 2.0 — 85 TBD μA 3.0 — 104 TBD μA 5.0 — 35 TBD μA 2.0 — 45 TBD μA 3.0 — 80 TBD μA 5.0 — 1.8 TBD μA 2.0 — 2.0 TBD μA 3.0 — 3.2 TBD μA 5.0 — 1.2 TBD nA 3.0 — 2.2 TBD nA 5.0 A/D Current(3) (not converting) — 10 TBD μA 3.0 VR Current(3) 3.0 — 11 TBD μA — 12 TBD μA 5.0 — 150 TBD μA 3.0 — 250 TBD μA 5.0 CVREF Current(3) Low Range CVREF Current(3) High Range T1 OSC Current(3) Op Amp Current(3) TBD = To Be Determined Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. The test conditions for all IDD measurements in Active Operation mode are: OSC1 = external square wave, from rail to rail; all I/O pins tri-stated, pulled to VDD; MCLR = VDD; WDT disabled. The supply current is mainly a function of the operating voltage and frequency. Other factors such as I/O pin loading and switching rate, oscillator type, internal code execution pattern and temperature also have an impact on the current consumption. The peripheral current is the sum of the base IDD or IPD and the additional current consumed when this peripheral is enabled. The peripheral Δ current can be determined by subtracting the base IDD or IPD current from this limit. Max values should be used when calculating total current consumption. 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. When A/D is off, it will not consume any current other than leakage current. The power-down current spec includes any such leakage from the A/D module. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 149 PIC16F785 18.4 DC Characteristics: PIC16F785-I (Industrial), PIC16F785-E (Extended) Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial -40°C ≤ TA ≤ +125°C for extended DC CHARACTERISTICS Param No. Sym Characteristic Min Typ† Max Units Conditions Input Low Voltage VIL I/O ports D030 with TTL buffer D030A D031 with Schmitt Trigger buffer VSS — 0.8 V 4.5V ≤ VDD ≤ 5.5V VSS — 0.15 VDD V Otherwise VSS — 0.2 VDD V Entire range 0.2 VDD V D032 MCLR, OSC1 (RC mode) VSS — D033 OSC1 (XT and LP modes)(1) VSS — 0.3 V D033A OSC1 (HS mode)(1) VSS — 0.3 VDD V Input High Voltage VIH I/O ports D040 D040A with TTL buffer D041 with Schmitt Trigger buffer — 2.0 (0.25 VDD + 0.8) — — VDD VDD V V 4.5V ≤ VDD ≤ 5.5V Otherwise 0.8 VDD — VDD V Entire range 0.8 VDD — VDD V 1.6 — VDD D042 MCLR D043 OSC1 (XT and LP modes) V (Note 1) D043A OSC1 (HS mode) 0.7 VDD — VDD V (Note 1) D043B OSC1 (RC mode) 0.9 VDD — VDD V 50* 250 400* μA VDD = 5.0V, VPIN = VSS — ±0.1 ±1 μA VSS ≤ VPIN ≤ VDD, Pin at high-impedance D070 IPUR PORTA Weak Pull-up Current Input Leakage Current(2) D060 IIL I/O ports D060A Analog inputs — ±0.1 ±1 μA VSS ≤ VPIN ≤ VDD D060B VREF — ±0.1 ±1 μA VSS ≤ VPIN ≤ VDD (3) — ±0.1 ±5 μA VSS ≤ VPIN ≤ VDD — ±0.1 ±5 μA VSS ≤ VPIN ≤ VDD, XT, HS and LP osc configuration I/O ports — — 0.6 V IOL = 8.5 mA, VDD = 4.5V OSC2/CLKOUT (RC mode) — — 0.6 V IOL = 1.6 mA, VDD = 4.5V (Ind.) IOL = 1.2 mA, VDD = 4.5V (Ext.) I/O ports VDD – 0.7 — — V IOH = -3.0 mA, VDD = 4.5V OSC2/CLKOUT (RC mode) VDD – 0.7 — — V IOH = -1.3 mA, VDD = 4.5V (Ind.) IOH = -1.0 mA, VDD = 4.5V (Ext.) — — TBD V RB6 pin D061 MCLR D063 OSC1 Output Low Voltage D080 VOL D083 Output High Voltage D090 VOH D092 D193* VOD Legend: * † Note 1: 2: 3: Open-Drain High Voltage TBD = To Be Determined These parameters are characterized but not tested. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended to use an external clock in RC mode. Negative current is defined as current sourced by the pin. 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. DS41249B-page 150 Preliminary © 2005 Microchip Technology Inc. PIC16F785 18.4 DC Characteristics: PIC16F785-I (Industrial), PIC16F785-E (Extended) (Continued) Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +85°C for industrial -40°C ≤ TA ≤ +125°C for extended DC CHARACTERISTICS Param No. Sym Characteristic Min Typ† Max Units — — 15* pF — — 50* pF Conditions Capacitive Loading Specs on Output Pins D100 COSC2 OSC2 pin D101 CIO All I/O pins In XT, HS and LP modes when external clock is used to drive OSC1 Data EEPROM Memory -40°C ≤ TA ≤ +85°C D120 ED Byte Endurance 100K 1M — E/W D120A ED Byte Endurance 10K 100K — E/W D121 VDRW VDD for Read/Write VMIN — 5.5 V D122 TDEW Erase/Write cycle time — 5 6 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 -40°C ≤ TA ≤ +85°C D130 EP Cell Endurance 10K 100K — E/W -40°C ≤ TA ≤ +85°C +85°C ≤ TA ≤ +125°C Using EECON1 to read/write VMIN = Minimum operating voltage Program Flash Memory D130A EP Cell Endurance D131 VPR VDD for Read D132 VPEW D133 TPEW D134 TRETD Legend: * † Note 1: 2: 3: 1K 10K — E/W VMIN — 5.5 V VDD for Erase/Write 4.5 — 5.5 V Erase/Write cycle time — 2 2.5 ms Characteristic Retention 40 — — +85°C ≤ TA ≤ +125°C VMIN = Minimum operating voltage Year Provided no other specifications are violated TBD = To Be Determined These parameters are characterized but not tested. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. In RC oscillator configuration, the OSC1/CLKIN pin is a Schmitt Trigger input. It is not recommended to use an external clock in RC mode. Negative current is defined as current sourced by the pin. 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. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 151 PIC16F785 18.5 Timing Parameter Symbology The timing parameter symbols have been created with one of the following formats: 1. TppS2ppS 2. TppS T F Frequency Lowercase letters (pp) and their meanings: pp cc CCP1 ck CLKOUT 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 FIGURE 18-2: T Time osc rd rw sc ss t0 t1 wr OSC1 RD RD or WR SCK SS T0CKI T1CKI WR P R V Z Period Rise Valid High-impedance LOAD CONDITIONS Load Condition 1 Load Condition 2 VDD/2 RL CL Pin CL Pin VSS VSS Legend: RL = 464Ω CL = 50 pF 15 pF FIGURE 18-3: for all pins for OSC2 output EXTERNAL CLOCK TIMING Q4 Q1 Q2 Q3 Q4 Q1 OSC1 1 3 3 4 4 2 CLKOUT DS41249B-page 152 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 18-1: Param No. Sym FOSC EXTERNAL CLOCK TIMING REQUIREMENTS Characteristic Min Typ† Max Units External CLKIN Frequency(1) — 32.768 — kHz DC DC DC — — DC 0.1 1 — — — — 32.768 4 — — — 0.3052 4 20 20 — — 4 4 20 — MHz MHz MHz kHz MHz MHz MHz MHz μs 50 — ∞ ns LP mode (complementary input only) XT mode HS mode EC mode LP Osc mode INTOSC mode RC Osc mode XT Osc mode HS Osc mode LP mode (complementary input only) HS Osc mode 50 — ∞ ns EC Osc mode Oscillator Frequency(1) 1 TOSC External CLKIN Period(1) Oscillator Period 2 3 TCY TosL, TosH (1) Conditions 250 — ∞ ns XT Osc mode — — 250 250 50 0.3052 250 — — — — — — 10,000 1,000 μs ns ns ns ns LP Osc mode INTOSC mode RC Osc mode XT Osc mode HS Osc mode Instruction Cycle Time(1) External CLKIN (OSC1) High External CLKIN Low 200 TCY DC ns TCY = 4/FOSC 2* — — μs LP oscillator, TOSC L/H duty cycle 20* — — ns HS oscillator, TOSC L/H duty cycle 100 * — — ns XT oscillator, TOSC L/H duty cycle 4 TosR, External CLKIN Rise — — 50* ns LP oscillator TosF External CLKIN Fall — — 25* ns XT oscillator — — 15* ns HS oscillator * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Instruction cycle period (TCY) equals four times the input oscillator time base period. All specified values are based on characterization data for that particular oscillator type under standard operating conditions with the device 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 OSC1 pin. When an external clock input is used, the ‘max’ cycle time limit is ‘DC’ (no clock) for all devices. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 153 PIC16F785 TABLE 18-2: Param No. F10 Sym FOSC F14 PRECISION INTERNAL OSCILLATOR PARAMETERS Characteristic Freq Min Tolerance Internal Calibrated INTOSC Frequency(1) Typ† Max Units MHz VDD = 3.5V, 25°C MHz 2.5V ≤ VDD ≤ 5.5V 0°C ≤ TA ≤ +85°C MHz 2.0V ≤ VDD ≤ 5.5V -40°C ≤ TA ≤ +85°C (Ind.) -40°C ≤ TA ≤ +125°C (Ext.) μs VDD = 2.0V, -40°C to +85°C μs VDD = 3.0V, -40°C to +85°C μs VDD = 5.0V, -40°C to +85°C ±1% ±2% 7.92 7.84 8.00 8.00 8.08 8.16 ±5% 7.60 8.00 8.40 TIOSCST Oscillator wake-up from Sleep start-up time* Conditions — — 10.3 TBD — — 9.0 TBD — — 6.5 TBD * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: To ensure these oscillator frequency tolerances, VDD and VSS must be capacitively decoupled as close to the device as possible. 0.1uF and 0.01uF values in parallel are recommended. FIGURE 18-4: CLKOUT AND I/O TIMING Q1 Q4 Q2 Q3 OSC1 11 10 22 23 CLKOUT 13 12 19 14 18 16 I/O pin (Input) 15 17 I/O pin (Output) New Value Old Value 20, 21 TABLE 18-3: Param No. CLKOUT AND I/O TIMING REQUIREMENTS Sym Characteristic Min Typ† Max Units Conditions 10 TOSH2CKL OSC1↑ to CLOUT↓ — 75 200 ns (Note 1) 11 TOSH2CKH OSC1↑ to CLOUT↑ — 75 200 ns (Note 1) 12 TCKR CLKOUT rise time — 35 100 ns (Note 1) 13 TCKF CLKOUT fall time — 35 100 ns (Note 1) 14 TCKL2IOV CLKOUT↓ to Port out valid — — 20 ns (Note 1) 15 TIOV2CKH Port in valid before CLKOUT↑ TOSC + 200 ns — — ns (Note 1) 16 TCKH2IOI 0 — — ns (Note 1) Port in hold after CLKOUT↑ * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. Note 1: Measurements are taken in RC mode where CLKOUT output is 4 x TOSC. DS41249B-page 154 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 18-3: Param No. 17 CLKOUT AND I/O TIMING REQUIREMENTS (CONTINUED) Sym Characteristic TOSH2IOV OSC1↑ (Q1 cycle) to Port out valid OSC1↑ (Q2 cycle) to Port input invalid (I/O in hold time) Min Typ† Max Units — 50 150 * ns — — 300 ns 100 — — ns 18 TOSH2IOI 19 TIOV2OSH Port input valid to OSC1↑ (I/O in setup time) 0 — — ns 20 TIOR Port output rise time — 10 40 ns 21 TIOF Port output fall time — 10 40 ns 22 TINP INT pin high or low time 25 — — ns 23 TRBP PORTA change INT high or low time TCY — — ns Conditions * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. Note 1: Measurements are taken in RC mode where CLKOUT output is 4 x TOSC. FIGURE 18-5: 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 34 31 34 I/O Pins © 2005 Microchip Technology Inc. Preliminary DS41249B-page 155 PIC16F785 FIGURE 18-6: BROWN-OUT RESET TIMING AND CHARACTERISTICS VDD VBOR (Device not in Brown-out Reset) (Device in Brown-out Reset) 36 Reset (due to BOR) Note 1: 64 ms delay only if PWRTE bit in Configuration Word is programmed to ‘0’. TABLE 18-4: Param No. 64 ms time-out(1) RESET, WATCHDOG TIMER, OSCILLATOR START-UP TIMER, POWER-UP TIMER AND BROWN-OUT RESET REQUIREMENTS Sym Characteristic Min Typ† Max Units Conditions 30 TMCL MCLR Pulse Width (low) 2 11 — 18 — 24 μs ms VDD = 5.0V, -40°C to +85°C Extended temperature 31 TWDT Watchdog Timer Time-out Period (No Prescaler) 10 10 17 17 25 30 ms ms VDD = 5.0V, -40°C to +85°C Extended temperature 32 TOST Oscillation Start-up Timer Period — 1024 TOSC — — TOSC = OSC1 period 33* TPWRT Power-up Timer Period 28* TBD 64 TBD 132* TBD ms ms VDD = 5.0V, -40°C to +85°C Extended Temperature 34 TIOZ I/O High-impedance from MCLR Low or Watchdog Timer Reset — — 2.0 μs 35 VBOR Brown-out Reset Voltage 2.025 — 2.175 V 36 TBOR Brown-out Reset Pulse Width 100* — — μs VDD ≤ VBOR (D005) Legend: TBD = To Be Determined. * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. DS41249B-page 156 Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 18-7: TIMER0 AND TIMER1 EXTERNAL CLOCK TIMINGS T0CKI 40 41 42 T1CKI 45 46 49 47 TMR0 or TMR1 TABLE 18-5: Param No. 40* TIMER0 AND TIMER1 EXTERNAL CLOCK REQUIREMENTS Sym TT0H Characteristic T0CKI High Pulse Width No Prescaler With Prescaler 41* TT0L T0CKI Low Pulse Width No Prescaler With Prescaler 42* TT0P T0CKI Period 45* TT1H T1CKI High Time Synchronous, No Prescaler Synchronous, with Prescaler Asynchronous 46* TT1L T1CKI Low Time Synchronous, No Prescaler Synchronous, with Prescaler Max Units 0.5 TCY + 20 — — ns 10 — — ns 0.5 TCY + 20 — — ns 10 — — ns Greater of: 20 or TCY + 40 N — — ns 0.5 TCY + 20 — — ns 15 — — ns 30 — — ns 0.5 TCY + 20 — — ns 15 — — ns Asynchronous 30 — — ns Greater of: 30 or TCY + 40 N — — ns TT1P T1CKI Input Period 48 FT1 Timer1 oscillator input frequency range (oscillator enabled by setting bit T1OSCEN) TCKEZTMR1 Delay from external clock edge to timer increment Asynchronous * † Typ† Synchronous 47* 49 Min 60 — — ns DC — 200* kHz 2 TOSC* — 7 TOSC* — Conditions N = prescale value (2, 4, ..., 256) N = prescale value (1, 2, 4, 8) These parameters are characterized but not tested. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 157 PIC16F785 FIGURE 18-8: CAPTURE/COMPARE/PWM TIMINGS (CCP) CCP1 (Capture mode) 50 51 52 CCP1 (Compare or PWM mode) 53 54 Note: Refer to Figure 18-2 for load conditions. TABLE 18-6: CAPTURE/COMPARE/PWM REQUIREMENTS (CCP) Param Symbol No. 50* TCCL Characteristic CCP1 input low time Min No Prescaler With Prescaler 51* TCCH CCP1 input high time No Prescaler With Prescaler 52* Typ† Max Units 0.5TCY + 20 — — ns 20 — — ns 0.5TCY + 20 — — ns 20 — — ns 3TCY + 40 N — — ns TCCP CCP1 input period 53* TCCR CCP1 output rise time — 25 50 ns 54* TCCF CCP1 output fall time — 25 45 ns Conditions N = prescale value (1,4 or 16) * These parameters are characterized but not tested. † Data in “Typ” column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. DS41249B-page 158 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 18-7: COMPARATOR SPECIFICATIONS Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C Comparator Specifications Param No. C01 Symbol Characteristics VOS Input Offset Voltage Min Typ Max Units — ±5 TBD mV Comments C02 VCM Input Common Mode Voltage 0 — VDD – 1.5 V C03 ILC Input Leakage Current — — 200* nA C04 CMRR Common Mode Rejection Ratio +70* — — dB C05 TRT Response Time(1) — — — — 20* 40* ns ns * Note 1: These parameters are characterized but not tested. Response time measured with one comparator input at (VDD – 1.5)/2, while the other input transitions from VSS to VDD – 1.5V. TABLE 18-8: COMPARATOR VOLTAGE REFERENCE (CVREF) SPECIFICATIONS Comparator Voltage Reference Specifications Param No. Internal Output to pin Min Typ Max Units Resolution — — VDD/24* VDD/32 — — LSb LSb Low Range (VRR = 1) High Range (VRR = 0) CV02 Absolute Accuracy — — — — ±1/4* ±1/2* LSb LSb Low Range (VRR = 1) High Range (VRR = 0) CV03 Unit Resistor Value (R) — 2K* — Ω CV04 Time(1) — — 10* μs CV01 * Note 1: Symbol CVRES Characteristics Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C Settling These parameters are characterized but not tested. Settling time measured while VRR = 1 and VR<3:0> transitions from 0000 to 1111. TABLE 18-9: VOLTAGE REFERENCE (VR) SPECIFICATIONS VR Voltage Reference Specifications Param No. Comments Symbol Characteristics Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C Min Typ Max Units VR01 VROUT VR voltage output TBD 1.200 TBD V VR02 TCVOUT Voltage drift temperature coefficient — 150 TBD ppm/°C VR03 ΔVROUT/ ΔVDD Voltage drift with respect to VDD regulation — 200 — μV/V VR04 TSTABLE Settling Time — 10 100* μs Comments 3.0V ≤ VDD ≤ 5.5V Legend: TBD = To Be Determined * These parameters are characterized but not tested. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 159 PIC16F785 TABLE 18-10: VOLTAGE REFERENCE OUTPUT (VREF) BUFFER SPECIFICATIONS Voltage Reference Output Buffer Specifications Param No. Symbol Characteristics VB01* CL External capacitor load VB02* ΔVOUT/ ΔIOUT Load regulation Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C Operating voltage 3.0V ≤ VDD ≤ 5.5V Min Typ Max Units — — 200 pF mV/mA Comments — 1 TBD — 1 TBD VREF=0.5V, IREF=±1ma VREF=1.2V, IREF=±1ma — 1 TBD VREF=3.6V, IREF=±1ma Legend: TBD = To Be Determined * These parameters are characterized but not tested. TABLE 18-11: OPERATIONAL AMPLIFIER (OPA) MODULE DC SPECIFICATIONS Standard Operating Conditions (unless otherwise stated) VCM = 0V, VOUT = VDD/2, VDD = 5.0V, VSS = 0V, CL = 50pF, RL = 100k Operating temperature -40°C ≤ TA ≤ +125°C OPA DC CHARACTERISTICS Param No. Sym Characteristics Min Typ Max Units Comments VOS Input Offset Voltage — ±5 — mV OPA02* OPA03* IB IOS Input current and impedance Input bias current Input offset bias current — — ±2* ±1* — — nA pA OPA04* OPA05* VCM CMR Common Mode Common mode input range Common mode rejection VSS TBD — 70 VDD – 1.4 — V dB VDD = 5.0V VCM = VDD/2, Freq = DC — — 90 60 — — dB dB No load Standard load VSS+100 — VDD – 100 mV To VDD/2 (20 kΩ connected to VDD, 20 kΩ + 20 pF to Vss) OPA01* OPA06A* AOL OPA06B* AOL Open Loop Gain DC Open loop gain DC Open loop gain OPA07* Vout Output Output voltage swing OPA08* Isc Output short circuit current — 25 TBD mA PSR Power Supply Power supply rejection 80 — — dB OPA10 Legend: TBD = To Be Determined * These parameters are characterized but not tested. DS41249B-page 160 Preliminary © 2005 Microchip Technology Inc. PIC16F785 TABLE 18-12: OPERATIONAL AMPLIFIER (OPA) MODULE AC SPECIFICATIONS OPA AC CHARACTERISTICS Param No. Symbol Characteristics Standard Operating Conditions (unless otherwise stated) VCM = 0V, VOUT = VDD/2, VDD = 5.0V, VSS = 0V, CL = 50 pF, RL = 100k Operating temperature -40°C ≤ TA ≤ +125°C Min Typ Max Units OPA11* GBWP Gain bandwidth product — 3 — MHz OPA12* TON Turn on time — 10 TBD μs OPA13* ΘM Phase margin — 60 — deg OPA14* SR Slew rate 2 — — V/μs Comments Legend: TBD = To Be Determined * These parameters are characterized but not tested. TABLE 18-13: TWO-PHASE PWM DEAD TIME DELAY SPECIFICATIONS Dead Time Delay Characteristics Param No. PW01* Symbol TDLY Characteristics Dead Time Delay Standard Operating Conditions (unless otherwise stated) Operating temperature -40°C ≤ TA ≤ +125°C Min Typ Max Units TBD 150 TBD ns Comments Fosc = 4 MHz, maximum delay, Complementary mode Legend: TBD = To Be Determined * These parameters are characterized but not tested. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 161 PIC16F785 TABLE 18-14: PIC16F785 A/D CONVERTER CHARACTERISTICS: Param No. Sym Characteristic Min Typ† Max Units Conditions A01 NR Resolution — — 10 bits A03 EIL Integral Error — — ±1 LSb VREF = 5.0V (external) bit A04 EDL Differential Error — — ±1 LSb No missing codes to 10 bits VREF = 5.0V (external) A05 EFS Full Scale Range 2.2* — 5.5* V A06 EOFF Offset Error — — ±1 LSb VREF = 5.0V (external) A07 EGN — — ±1 LSb VREF = 5.0V (external) Gain Error (2) — — — VDD + 0.3 V — VREF(5) V — — 10 kΩ — — 150 μA — — 1 A10 — Monotonicity — A20 A20A VREF Reference Voltage 2.2(4) 1.0 guaranteed — A25 VAIN Analog Input Voltage VSS A30 ZAIN Recommended Impedance of Analog Voltage Source A50 IREF VREF Input Current*(3) VSS ≤ VAIN ≤ VREF Absolute minimum to ensure 10-bit accuracy During VAIN acquisition. Based on differential of VHOLD to mA VAIN. Transient during A/D conversion cycle. * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: Total Absolute Error includes Integral, Differential, Offset and Gain Errors. 2: The A/D conversion result never decreases with an increase in the input voltage and has no missing codes. 3: VREF current is from external VREF or VDD pin, whichever is selected as reference input. 4: Only limited when VDD is at or below 2.5V. If VDD is above 2.5V, VREF is allowed to go as low as 1.0V. 5: Analog input voltages are allowed up to VDD, however the conversion accuracy is limited to VSS to VREF. DS41249B-page 162 Preliminary © 2005 Microchip Technology Inc. PIC16F785 FIGURE 18-9: PIC16F785 A/D CONVERSION TIMING (NORMAL MODE) BSF ADCON0, GO 134 1 TCY (TOSC/2)(1) 131 Q4 130 A/D CLK 9 A/D DATA 8 7 3 6 2 1 0 NEW_DATA OLD_DATA ADRES 1 TCY ADIF GO SAMPLE Note 1: DONE SAMPLING STOPPED 132 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. TABLE 18-15: PIC16F785 A/D CONVERSION REQUIREMENTS Param No. Sym 130 TAD 130 TAD Characteristic A/D Clock Period A/D Internal RC Oscillator Period 131 TCNV Conversion Time (not including Acquisition Time)(1) 132 TACQ Acquisition Time 134 TGO * † Note 1: 2: Q4 to A/D Clock Start Min Typ† Max Units Conditions 1.6 — — μs TOSC-based, VREF ≥ 3.0V 3.0* — — μs TOSC-based, VREF full range 3.0* 6.0 9.0* μs ADCS<1:0> = 11 (RC mode) At VDD = 2.5V 2.0* 4.0 6.0* μs At VDD = 5.0V — 11 — TAD Set GO bit to new data in A/D result register (Note 2) 11.5 — μs 5* — — μs The minimum time is the amplifier settling time. This may be used if the “new” input voltage has not changed by more than 1 LSb (i.e., 4.1 mV @ 4.096V) from the last sampled voltage (as stored on CHOLD). — TOSC/2 — — 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. These parameters are characterized but not tested. Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. ADRESH and ADRESL registers may be read on the following TCY cycle. See Table 12-2 for minimum conditions. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 163 PIC16F785 FIGURE 18-10: PIC16F785 A/D CONVERSION TIMING (SLEEP MODE) BSF ADCON0, GO 134 (TOSC/2 + TCY)(1) 1 TCY 131 Q4 130 A/D CLK 9 A/D DATA 8 7 3 6 2 1 NEW_DATA OLD_DATA ADRES 0 ADIF 1 TCY GO DONE Note 1: SAMPLING STOPPED 132 SAMPLE 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. TABLE 18-16: PIC16F785 A/D CONVERSION REQUIREMENTS (SLEEP MODE) Param No. 130 Sym TAD Characteristic A/D Internal RC Oscillator Period 131 TCNV Conversion Time (not including Acquisition Time)(1) 132 TACQ Acquisition Time 134 TGO Q4 to A/D Clock Start Min Typ† Max Units Conditions 3.0* 6.0 9.0* μs ADCS<1:0> = 11 (RC mode) At VDD = 2.5V 2.0* 4.0 6.0* μs At VDD = 5.0V — 11 — TAD (Note 2) 11.5 — μs 5* — — μs The minimum time is the amplifier settling time. This may be used if the “new” input voltage has not changed by more than 1 LSb (i.e., 4.1 mV @ 4.096V) from the last sampled voltage (as stored on CHOLD). — TOSC/2 + TCY — — 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. * These parameters are characterized but not tested. † Data in ‘Typ’ column is at 5.0V, 25°C unless otherwise stated. These parameters are for design guidance only and are not tested. Note 1: ADRES register may be read on the following TCY cycle. 2: See Table 12-1 for minimum conditions. DS41249B-page 164 Preliminary © 2005 Microchip Technology Inc. PIC16F785 19.0 DC AND AC CHARACTERISTICS GRAPHS AND TABLES Graphs are not available at this time. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 165 PIC16F785 NOTES: DS41249B-page 166 Preliminary © 2005 Microchip Technology Inc. PIC16F785 20.0 PACKAGING INFORMATION 20.1 Package Marking Information 20-Lead PDIP Example XXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXX YYWWNNN PIC16F785-I/P 0410017 20-Lead SOIC (.300”) Example XXXXXXXXXXXXXX XXXXXXXXXXXXXX XXXXXXXXXXXXXX PIC16F785 -E/SO 0410017 YYWWNNN 20-Lead SSOP Example XXXXXXXXXXX XXXXXXXXXXX YYWWNNN Legend: XX...X Y YY WW NNN e3 * Note: * PIC16F785 -I/SS 0410017 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. Standard PICmicro device marking consists of Microchip part number, year code, week code, and traceability code. For PICmicro device marking beyond this, certain price adders apply. Please check with your Microchip Sales Office. For QTP devices, any special marking adders are included in QTP price. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 167 PIC16F785 20.2 Package Details The following sections give the technical details of the packages. 20-Lead Plastic Dual In-line (P) – 300 mil Body (PDIP) E1 D 2 n α 1 E A2 A L c A1 β B1 eB p B Units Dimension Limits n p MIN INCHES* NOM 20 .100 .155 .130 MAX MILLIMETERS NOM 20 2.54 3.56 3.94 2.92 3.30 0.38 7.49 7.87 6.10 6.35 26.04 26.24 3.05 3.30 0.20 0.29 1.40 1.52 0.36 0.46 7.87 9.40 5 10 5 10 MIN Number of Pins Pitch Top to Seating Plane A .140 .170 Molded Package Thickness A2 .115 .145 Base to Seating Plane A1 .015 Shoulder to Shoulder Width E .295 .310 .325 Molded Package Width E1 .240 .250 .260 Overall Length D 1.025 1.033 1.040 Tip to Seating Plane L .120 .130 .140 c Lead Thickness .008 .012 .015 Upper Lead Width B1 .055 .060 .065 Lower Lead Width B .014 .018 .022 Overall Row Spacing § eB .310 .370 .430 α Mold Draft Angle Top 5 10 15 β Mold Draft Angle Bottom 5 10 15 * Controlling Parameter § Significant Characteristic Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MS-001 Drawing No. C04-019 DS41249B-page 168 Preliminary MAX 4.32 3.68 8.26 6.60 26.42 3.56 0.38 1.65 0.56 10.92 15 15 © 2005 Microchip Technology Inc. PIC16F785 20-Lead Plastic Small Outline (SO) – Wide, 300 mil Body (SOIC) E E1 p D 2 B n 1 h α 45° c A2 A φ β A1 L Units Dimension Limits n p Number of Pins Pitch Overall Height Molded Package Thickness Standoff § Overall Width Molded Package Width Overall Length Chamfer Distance Foot Length Foot Angle Lead Thickness Lead Width Mold Draft Angle Top Mold Draft Angle Bottom * Controlling Parameter § Significant Characteristic A A2 A1 E E1 D h L φ c B α β MIN .093 .088 .004 .394 .291 .496 .010 .016 0 .009 .014 0 0 INCHES* NOM 20 .050 .099 .091 .008 .407 .295 .504 .020 .033 4 .011 .017 12 12 MAX .104 .094 .012 .420 .299 .512 .029 .050 8 .013 .020 15 15 MILLIMETERS NOM 20 1.27 2.36 2.50 2.24 2.31 0.10 0.20 10.01 10.34 7.39 7.49 12.60 12.80 0.25 0.50 0.41 0.84 0 4 0.23 0.28 0.36 0.42 0 12 0 12 MIN MAX 2.64 2.39 0.30 10.67 7.59 13.00 0.74 1.27 8 0.33 0.51 15 15 Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .010” (0.254mm) per side. JEDEC Equivalent: MS-013 Drawing No. C04-094 © 2005 Microchip Technology Inc. Preliminary DS41249B-page 169 PIC16F785 20-Lead Plastic Shrink Small Outline (SS) – 209 mil Body, 5.30 mm (SSOP) DS41249B-page 170 Preliminary © 2005 Microchip Technology Inc. PIC16F785 APPENDIX A: DATA SHEET REVISION HISTORY Revision A APPENDIX B: MIGRATING FROM OTHER PICmicro® DEVICES This is a new data sheet. This discusses some of the issues in migrating from the PIC16F684 PICmicro device to the PIC16F785. Revision B B.1 Updates throughout document. TABLE B-1: PIC16F684 to PIC16F785 FEATURE COMPARISON Feature PIC16F684 PIC16F785 Max Operating Speed 20 MHz 20 MHz Max Program Memory (Words) 2048 2048 SRAM (bytes) 128 128 A/D Resolution 10-bit 10-bit Data EEPROM (bytes) 256 256 Timers (8/16-bit) 2/1 2/1 Oscillator modes 8 8 Brown-out Reset Y Y Internal Pull-ups RA0/1/2/4/5 MCLR RA0/1/2/3/4/5 MCLR Interrupt-on-change RA0/1/2/3/4/5 RA0/1/2/3/4/5 Comparator © 2005 Microchip Technology Inc. 2 CCP ECCP Y Op Amps N 2 PWM N Two-Phase Ultra Low-Power Wake-up Y N Extended WDT Y Y Software Control Option of WDT/BOR Y Y INTOSC Frequencies 32 kHz 8 MHz 32 kHz 8 MHz Clock Switching Y Y Preliminary DS41249B-page 171 PIC16F785 NOTES: DS41249B-page 172 Preliminary © 2005 Microchip Technology Inc. PIC16F785 INDEX A A/D ...................................................................................... 79 Acquisition Requirements ........................................... 86 Analog Port Pins ......................................................... 80 Associated Registers .................................................. 89 Block Diagram............................................................. 79 Calculating Acquisition Time....................................... 86 Channel Selection....................................................... 80 Configuration and Operation....................................... 80 Configuring.................................................................. 85 Configuring Interrupt ................................................... 85 Conversion Clock........................................................ 80 Effects of Reset........................................................... 89 Internal Sampling Switch (RSS) Impedance................ 86 Operation During Sleep .............................................. 88 Output Format............................................................. 81 Reference Voltage (VREF)........................................... 80 Source Impedance...................................................... 86 Special Event Trigger.................................................. 89 Specifications............................................ 162, 163, 164 Starting a Conversion ................................................. 81 Using the ECCP Trigger ............................................. 89 Absolute Maximum Ratings .............................................. 143 AC Characteristics Load Conditions ........................................................ 152 ADCON0 Register............................................................... 83 ADCON1 Register............................................................... 84 Analog-to-Digital Converter. See A/D ANSEL Register .............................................. 93, 94, 96, 100 ANSEL0 Register ................................................................ 82 ANSEL1 Register ................................................................ 82 Assembler MPASM Assembler................................................... 137 B Block Diagrams (CCP) Capture Mode Operation ................................. 58 A/D .............................................................................. 79 Analog Input Model ..................................................... 87 CCP PWM................................................................... 60 Clock Source............................................................... 23 Comparator 1 .............................................................. 64 Comparator 2 .............................................................. 66 Compare ..................................................................... 58 CVref........................................................................... 71 Fail-Safe Clock Monitor (FSCM) ................................. 31 In-Circuit Serial Programming Connections.............. 125 Interrupt Logic ........................................................... 118 On-Chip Reset Circuit ............................................... 109 OPA Module................................................................ 75 PIC16F684.................................................................... 5 RA0 Pin....................................................................... 38 RA1 Pin....................................................................... 38 RA2 Pin....................................................................... 39 RA3 Pin....................................................................... 39 RA4 Pin....................................................................... 40 RA5 Pin....................................................................... 40 RB4 and RB5 Pins ...................................................... 43 RB6 Pin....................................................................... 43 RB7 Pin....................................................................... 43 RC0 and RC1 Pins...................................................... 43 RC0, RC6 and RC7 Pins ............................................ 46 RC1 Pin....................................................................... 46 © 2005 Microchip Technology Inc. RC2 and RC3 Pins ..................................................... 47 RC4 Pin ...................................................................... 47 RC5 Pin ...................................................................... 48 Resonator Operation .................................................. 25 Timer1 ........................................................................ 51 Timer2 ........................................................................ 56 TMR0/WDT Prescaler ................................................ 49 Two-Phase PWM Complementary Output Mode .......................... 100 Simplified Diagram ............................................. 92 Single Phase Example ....................................... 98 VR Reference ............................................................. 74 Watchdog Timer (WDT)............................................ 121 Brown-out Reset (BOR).................................................... 110 Associated registers ................................................. 112 Calibration ................................................................ 111 Specifications ........................................................... 156 Timing and Characteristics ....................................... 156 C C Compilers MPLAB C17.............................................................. 138 MPLAB C18.............................................................. 138 MPLAB C30.............................................................. 138 Capture Module. See Capture/Compare/PWM (CCP) Capture/Compare/PWM (CCP) .......................................... 57 Associated Registers.................................................. 62 Associated registers w/ Capture/Compare/Timer1..... 59 Capture Mode............................................................. 58 CCP1 Pin Configuration ............................................. 58 Compare Mode........................................................... 58 CCP1 Pin Configuration ..................................... 59 Software Interrupt Mode ..................................... 59 Special Event Trigger and A/D Conversions ...... 59 Timer1 Mode Selection....................................... 59 Prescaler .................................................................... 58 PWM Mode................................................................. 60 Duty Cycle .......................................................... 61 Effects of Reset .................................................. 62 Example PWM Frequencies and Resolutions .... 61 Operation in Power Managed Modes ................. 62 Operation with Fail-Safe Clock Monitor .............. 62 Setup for Operation ............................................ 62 Setup for PWM Operation .................................. 62 Specifications ........................................................... 158 Timer Resources ........................................................ 57 CCP. See Capture/Compare/PWM (CCP) CCP1CON Register............................................................ 57 CCPR1H Register............................................................... 57 CCPR1L Register ............................................................... 57 Clock Sources..................................................................... 23 CM1CON0 .......................................................................... 65 CM2CON1 .......................................................................... 68 Code Examples Assigning Prescaler to Timer0.................................... 50 Assigning Prescaler to WDT....................................... 50 Changing Between Capture Prescalers ..................... 58 Data EEPROM Read................................................ 105 Data EEPROM Write ................................................ 105 EEPROM Write Verify .............................................. 105 Indirect Addressing..................................................... 22 Initializing A/D............................................................. 85 Initializing PORTA ...................................................... 35 Initializing PORTB ...................................................... 42 Preliminary DS41249B-page 173 PIC16F785 Initializing PORTC....................................................... 45 Interrupt Context Saving ........................................... 120 Code Protection ................................................................ 125 Comparator Module ............................................................ 63 Associated registers.................................................... 74 C1 Output State Versus Input Conditions ................... 63 C2 Output State Versus Input Conditions ................... 66 Comparator Interrupts ................................................. 69 Effects of Reset........................................................... 69 Comparator Voltage Reference (CVREF) Specifications ............................................................ 159 Comparators C2OUT as T1 Gate ..................................................... 52 Specifications ............................................................ 159 Compare Module. See Capture/Compare/PWM (CCP) CONFIG Register.............................................................. 108 Configuration Bits.............................................................. 107 CPU Features ................................................................... 107 Customer Change Notification Service ................................. 1 Customer Support ................................................................. 1 D Data EEPROM Memory Associated registers.................................................. 106 Code Protection ................................................ 103, 106 Data Memory......................................................................... 9 DC Characteristics Extended and Industrial ............................................ 150 Industrial and Extended ............................................ 145 Demonstration Boards PICDEM 1 ................................................................. 140 PICDEM 17 ............................................................... 141 PICDEM 18R ............................................................ 141 PICDEM 2 Plus ......................................................... 140 PICDEM 3 ................................................................. 140 PICDEM 4 ................................................................. 140 PICDEM LIN ............................................................. 141 PICDEM USB............................................................ 141 PICDEM.net Internet/Ethernet .................................. 140 Development Support ....................................................... 137 Device Overview ................................................................... 5 E EEADR Register ............................................................... 103 EECON1 Register ............................................................. 104 EECON2 Register ............................................................. 104 EEDAT Register................................................................ 103 EEPROM Data Memory Avoiding Spurious Write............................................ 105 Reading..................................................................... 105 Write Verify ............................................................... 105 Writing ....................................................................... 105 Effects of Reset A/D module ................................................................. 89 Comparator module .................................................... 69 OPA module................................................................ 77 PWM mode ................................................................. 62 Electrical Specifications .................................................... 143 Errata .................................................................................... 3 Evaluation and Programming Tools .................................. 141 DS41249B-page 174 F Fail-Safe Clock Monitor ...................................................... 31 Fail-Safe Condition Clearing....................................... 32 Reset and Wake-up from Sleep.................................. 32 Firmware Instructions ....................................................... 127 Fuses. See Configuration Bits G General Purpose Register File ............................................. 9 I ID Locations...................................................................... 125 In-Circuit Debugger........................................................... 126 In-Circuit Serial Programming (ICSP)............................... 125 Indirect Addressing, INDF and FSR registers..................... 22 Instruction Format............................................................. 127 Instruction Set................................................................... 127 ADDLW..................................................................... 129 ADDWF..................................................................... 129 ANDLW..................................................................... 129 ANDWF..................................................................... 129 BCF .......................................................................... 129 BSF........................................................................... 129 BTFSC ...................................................................... 129 BTFSS ...................................................................... 129 CALL......................................................................... 130 CLRF ........................................................................ 130 CLRW ....................................................................... 130 CLRWDT .................................................................. 130 COMF ....................................................................... 130 DECF ........................................................................ 130 DECFSZ ................................................................... 130 GOTO ....................................................................... 131 INCF ......................................................................... 131 INCFSZ..................................................................... 131 IORLW ...................................................................... 131 IORWF...................................................................... 131 MOVF ....................................................................... 131 MOVLW .................................................................... 132 MOVWF .................................................................... 132 NOP .......................................................................... 132 RETFIE ..................................................................... 132 RETLW ..................................................................... 133 RETURN................................................................... 133 RLF ........................................................................... 133 RRF .......................................................................... 134 SLEEP ...................................................................... 134 SUBLW ..................................................................... 134 SUBWF..................................................................... 135 SWAPF ..................................................................... 135 TRIS ......................................................................... 135 XORLW .................................................................... 136 XORWF .................................................................... 136 Summary Table ........................................................ 128 INTCON Register................................................................ 17 Internal Oscillator Block INTOSC Specifications ................................................... 154 Internal Sampling Switch (RSS) Impedance........................ 86 Internet Address ................................................................... 1 Interrupts........................................................................... 117 (CCP) Compare .......................................................... 58 A/D.............................................................................. 85 Associated registers ................................................. 119 Comparator................................................................. 69 Preliminary © 2005 Microchip Technology Inc. PIC16F785 Context Saving.......................................................... 120 Data EEPROM Memory Write .................................. 104 Interrupt-on-change .................................................... 37 Oscillator Fail (OSF) ................................................... 31 PORTA Interrupt-on-change ..................................... 118 RA2/INT .................................................................... 118 TMR0 ........................................................................ 118 TMR1 .......................................................................... 52 TMR2 to PR2 Match ............................................. 55, 56 INTOSC Specifications ..................................................... 154 IOCA (Interrupt-on-Change) ............................................... 37 IOCA Register ..................................................................... 37 OPA2CON Register ............................................................ 76 OPCODE Field Descriptions ............................................. 127 Operational Amplifier (OPA) Module................................... 75 AC Specifications...................................................... 161 Associated Registers .................................................. 77 DC Specifications...................................................... 161 OPTION_REG Register ...................................................... 16 OSCCON Register .............................................................. 33 Oscillator Associated registers.................................................... 33 Oscillator Specifications .................................................... 153 Oscillator Start-up Timer (OST) Specifications............................................................ 156 Oscillator Switching Fail-Safe Clock Monitor............................................... 31 Two-Speed Clock Start-up.......................................... 30 PIR1 Register ..................................................................... 19 PORTA ............................................................................... 35 Additional Pin Functions ............................................. 36 Interrupt-on-change ............................................ 37 Weak Pull-up ...................................................... 36 Associated registers ................................................... 41 Pin Descriptions and Diagrams .................................. 38 RA0............................................................................. 38 RA1............................................................................. 38 RA2............................................................................. 39 RA3............................................................................. 39 RA4............................................................................. 40 RA5............................................................................. 40 Specifications ........................................................... 154 PORTB ............................................................................... 42 Associated registers ................................................... 44 Pin Descriptions and Diagrams .................................. 43 RB4............................................................................. 43 RB5............................................................................. 43 RB6............................................................................. 43 RB7............................................................................. 43 PORTC ............................................................................... 45 Associated registers ............................................. 33, 48 Pin Descriptions and Diagrams .................................. 46 RC0 ............................................................................ 46 RC1 ............................................................................ 46 RC2 ............................................................................ 47 RC3 ............................................................................ 47 RC4 ............................................................................ 47 RC5 ............................................................................ 48 RC6 ............................................................................ 46 RC7 ............................................................................ 46 Specifications ........................................................... 154 Power-Down Mode (Sleep)............................................... 123 Power-up Timer (PWRT) .................................................. 110 Specifications ........................................................... 156 Power-up Timing Delays................................................... 112 Precision Internal Oscillator Parameters .......................... 154 Prescaler Shared WDT/Timer0................................................... 50 Switching Prescaler Assignment ................................ 50 PRO MATE II Universal Device Programmer ................... 139 Product Identification ........................................................ 175 Program Memory .................................................................. 9 Map and Stack.............................................................. 9 Programming, Device Instructions.................................... 127 PWM. See Two-Phase PWM PWMCLK Register.............................................................. 94 PWMCON0 Register........................................................... 93 PWMCON1 Register......................................................... 100 PWMPH1 Register.............................................................. 95 PWMPH2 Register.............................................................. 96 P R Packaging ......................................................................... 167 Marking ..................................................................... 167 PDIP Details.............................................................. 168 PCL and PCLATH ............................................................... 21 Stack ........................................................................... 21 PCON Register ................................................................. 112 PICkit 1 Flash Starter Kit................................................... 141 PICSTART Plus Development Programmer ..................... 140 PIE1 Register ...................................................................... 18 Pin Diagram .......................................................................... 2 Pinout Descriptions PIC16F684.................................................................... 6 Reader Response................................................................. 2 Read-Modify-Write Operations ......................................... 127 REFCON (VR control) ........................................................ 73 Register IOCA (Interrupt-on-Change) ....................................... 37 WPUA (Weak Pull-up PORTA)................................... 36 Registers ADCON0 (A/D Control 0)............................................ 83 ADCON1 (A/D Control 1)............................................ 84 ANSEL (Analog Select) .......................... 93, 94, 96, 100 ANSEL0 (Analog Select 0) ......................................... 82 ANSEL1 (Analog Select 1) ......................................... 82 L Load Conditions ................................................................ 152 M MCLR ................................................................................ 110 Internal ...................................................................... 110 Memory Organization............................................................ 9 Data .............................................................................. 9 Data EEPROM Memory............................................ 103 Program ........................................................................ 9 Microchip Internet Web Site .................................................. 1 Migrating from other PICmicro Devices ............................ 171 MPLAB ASM30 Assembler, Linker, Librarian ................... 138 MPLAB ICD 2 In-Circuit Debugger ................................... 139 MPLAB ICE 2000 High-Performance Universal In-Circuit Emulator .................................................... 139 MPLAB ICE 4000 High-Performance Universal In-Circuit Emulator .................................................... 139 MPLAB Integrated Development Environment Software .. 137 MPLAB PM3 Device Programmer .................................... 139 MPLINK Object Linker/MPLIB Object Librarian ................ 138 O © 2005 Microchip Technology Inc. Preliminary DS41249B-page 175 PIC16F785 CCP1CON (CCP Operation)....................................... 57 CCPR1H ..................................................................... 57 CCPR1L ...................................................................... 57 CM1CON0 (C1 Control) .............................................. 65 CM1CON0 (C2 Control) CM2CON0 .......................................................... 67 CM2CON1 (C2 control)............................................... 68 CONFIG (Configuration Word).................................. 108 Data Memory Map ...................................................... 10 EEADR (EEPROM Address) .................................... 103 EECON1 (EEPROM Control 1)................................. 104 EECON2 (EEPROM Control 2)................................. 104 EEDAT (EEPROM Data) .......................................... 103 INTCON (Interrupt Control) ......................................... 17 IOCA (Interrupt-on-change PORTA) ........................... 37 Op Amp 2 Control Register (OPA2CON) .................... 76 OPTION_REG (Option) .............................................. 16 OSCCON (Oscillator Control) ..................................... 33 PCON (Power Control) ............................................. 112 PIE1 (Peripheral Interrupt Enable 1) ........................... 18 PIR1 (Peripheral Interrupt Register 1) ........................ 19 PORTA........................................................................ 35 PORTB........................................................................ 42 PORTC ....................................................................... 45 PWMCLK (PWM clock control) ................................... 94 PWMCON0 (PWM control 0) ...................................... 93 PWMCON1 (PWM control 1) .................................... 100 PWMPH1 (PWM Phase 1 control) .............................. 95 PWMPH2 (PWM Phase 2 control) .............................. 96 REFCON (VR control)................................................. 73 Reset Values............................................................. 114 Reset Values (special registers) ............................... 116 Special Function registers............................................. 9 Special Register Summary ............................. 12, 13, 14 Status .......................................................................... 15 T1CON (Timer1 Control)............................................. 53 T2CON (Timer2 Control)............................................. 55 TRISA (Tri-state PORTA) ........................................... 36 TRISB (Tri-state PORTB) ........................................... 42 TRISC (Tri-state PORTC) ........................................... 45 WDTCON (Watchdog Timer Control)........................ 122 WPUA (Weak Pull-up PORTA) ................................... 36 Resets ............................................................................... 109 Power-On Reset ....................................................... 110 Revision History ................................................................ 171 RRF Instruction ................................................................. 134 S SLEEP Instruction ............................................................. 134 Software Simulator (MPLAB SIM)..................................... 138 Software Simulator (MPLAB SIM30)................................. 138 Special Event Trigger.......................................................... 89 Special Function registers..................................................... 9 Specifications .................................................................... 162 STATUS Register................................................................ 15 SUBLW Instruction............................................................ 134 SUBWF Instruction............................................................ 135 SWAPF Instruction............................................................ 135 T Time-out Sequence........................................................... 112 Timer0 ................................................................................. 49 Associated registers.................................................... 50 External Clock ............................................................. 50 Interrupt....................................................................... 49 Operation .................................................................... 49 DS41249B-page 176 Prescaler .................................................................... 50 Specifications ........................................................... 157 Timer1................................................................................. 51 Associated registers ................................................... 54 Asynchronous Counter Mode ..................................... 54 Reading and Writing ........................................... 54 Interrupt ...................................................................... 52 Modes of Operations .................................................. 52 Operation During Sleep .............................................. 54 Oscillator..................................................................... 54 Prescaler .................................................................... 52 Specifications ........................................................... 157 Timer1 Gate Inverting Gate ..................................................... 52 Selecting Source ................................................ 52 TMR1H Register ......................................................... 51 TMR1L Register.......................................................... 51 Timer2................................................................................. 55 Associated registers ................................................... 56 Operation .................................................................... 55 Postscaler ................................................................... 55 PR2 Register .............................................................. 55 Prescaler .................................................................... 55 TMR2 Register............................................................ 55 TMR2 to PR2 Match Interrupt............................... 55, 56 Timing Diagrams A/D Conversion......................................................... 163 A/D Conversion (Sleep Mode) .................................. 164 Brown-out Reset (BOR)............................................ 156 Brown-out Reset Situations ...................................... 111 Capture/Compare/PWM (CCP) ................................ 158 CLKOUT and I/O ...................................................... 154 External Clock........................................................... 152 Fail-Safe Clock Monitor (FSCM)................................. 32 INT Pin Interrupt ....................................................... 119 Reset, WDT, OST and Power-up Timer ................... 155 Time-out Sequence Case 1 .............................................................. 113 Case 2 .............................................................. 113 Case 3 .............................................................. 113 Timer0 and Timer1 External Clock ........................... 157 Timer1 Incrementing Edge ......................................... 52 Two-Phase PWM Complementary Output .................................... 101 Start-up............................................................... 97 Two-Speed Start-up.................................................... 31 Two-Phase PWM Auto-Shutdown ................................................... 97 Wake-up from Interrupt............................................. 124 Timing Parameter Symbology .......................................... 152 TRIS Instruction ................................................................ 135 TRISA Register................................................................... 36 TRISB Register................................................................... 42 TRISC Register................................................................... 45 Two-Phase PWM................................................................ 91 Activating .................................................................... 91 Active Output Level .................................................... 92 Associated registers ................................................. 101 Auto-shutdown............................................................ 92 Clock control (PWMCLK)............................................ 94 Control Register 0 (PWMCON0)................................. 93 Control Register 1 (PWMCON1)............................... 100 Master/Slave Operation .............................................. 91 Output Blanking .......................................................... 91 Phase 1 control (PWMPH1)........................................ 95 Preliminary © 2005 Microchip Technology Inc. PIC16F785 Phase 2 control (PWMPH1)........................................ 96 PWM Duty Cycle......................................................... 91 PWM Frequency ......................................................... 91 PWM Period................................................................ 91 PWM Phase ................................................................ 91 PWM Phase resolution ............................................... 91 Shutdown .................................................................... 92 Two-Phase PWM Dead Time Delay ...................................................... 162 Two-Speed Clock Start-up Mode ........................................ 30 V Voltage Reference (VR) Specifications............................................................ 160 Voltage Reference Output (VREF) BUFFER Specifications............................................................ 160 Voltage References ............................................................ 71 Associated registers.................................................... 74 Configuring CVref ....................................................... 71 CVref (Comparator Reference)................................... 71 CVref Accuracy ........................................................... 71 Fixed VR reference ..................................................... 73 VR Stabilization........................................................... 74 VREF. SEE A/D Reference Voltage W Wake-up Using Interrupts ................................................. 123 Watchdog Timer (WDT) .................................................... 121 Associated registers.................................................. 122 Clock Source............................................................. 121 Modes ....................................................................... 121 Period........................................................................ 121 Specifications............................................................ 156 WDTCON Register ........................................................... 122 WPUA (Weak Pull-up PORTA) ........................................... 36 WPUA Register ................................................................... 36 WWW Address...................................................................... 1 WWW, On-Line Support ....................................................... 3 X XORLW Instruction ........................................................... 136 XORWF Instruction ........................................................... 136 © 2005 Microchip Technology Inc. Preliminary DS41249B-page 177 PIC16F785 NOTES: DS41249B-page 178 Preliminary © 2005 Microchip Technology Inc. PIC16F785 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 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. • • • • • 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 In addition, there is a Development Systems Information Line which lists the latest versions of Microchip’s development systems software products. This line also provides information on how customers can receive currently available upgrade kits. The Development numbers are: Systems Information Line 1-800-755-2345 – United States and most of Canada 1-480-792-7302 – Other International Locations To register, access the Microchip web site at www.microchip.com, click on Customer Change Notification and follow the registration instructions. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 179 PIC16F785 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? Device: PIC16F785 Y N Literature Number: DS41249B 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? DS41249B-page 180 Preliminary © 2005 Microchip Technology Inc. PIC16F785 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. Device X Temperature Range /XX XXX Package Pattern Examples: a) b) Device: PIC16F785, PIC16F785T(1): Temperature Range: I E Package: P SO SS Pattern: 3-Digit Pattern Code for QTP (blank otherwise) = = PIC16F785 – E/P 301 = Extended Temp., PDIP package, 20 MHz, QTP pattern #301 PIC16F785 – I/SO = Industrial Temp., SOIC package, 20 MHz -40°C to +85°C -40°C to +125°C = = = PDIP SOIC (Gull wing, 300 mil body) SSOP(5.3 mm) Note 1: T = in tape and reel SOIC, and SSOP packages only. Sales and Support Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. 2. 3. Your local Microchip sales office The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products. © 2005 Microchip Technology Inc. Preliminary DS41249B-page 181 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 Australia - Sydney Tel: 61-2-9868-6733 Fax: 61-2-9868-6755 India - Bangalore Tel: 91-80-2229-0061 Fax: 91-80-2229-0062 China - Beijing Tel: 86-10-8528-2100 Fax: 86-10-8528-2104 India - New Delhi Tel: 91-11-5160-8631 Fax: 91-11-5160-8632 Austria - Weis Tel: 43-7242-2244-399 Fax: 43-7242-2244-393 Denmark - Ballerup Tel: 45-4450-2828 Fax: 45-4485-2829 China - Chengdu Tel: 86-28-8676-6200 Fax: 86-28-8676-6599 Japan - Kanagawa Tel: 81-45-471- 6166 Fax: 81-45-471-6122 France - Massy Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79 China - Fuzhou Tel: 86-591-8750-3506 Fax: 86-591-8750-3521 Korea - Seoul Tel: 82-2-554-7200 Fax: 82-2-558-5932 or 82-2-558-5934 Germany - Ismaning Tel: 49-89-627-144-0 Fax: 49-89-627-144-44 Atlanta Alpharetta, GA Tel: 770-640-0034 Fax: 770-640-0307 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 China - Hong Kong SAR Tel: 852-2401-1200 Fax: 852-2401-3431 China - Shanghai Tel: 86-21-5407-5533 Fax: 86-21-5407-5066 China - Shenyang Tel: 86-24-2334-2829 Fax: 86-24-2334-2393 Philippines - Manila Tel: 011-632-634-9065 Fax: 011-632-634-9069 China - Shenzhen Tel: 86-755-8203-2660 Fax: 86-755-8203-1760 China - Shunde Tel: 86-757-2839-5507 Fax: 86-757-2839-5571 China - Qingdao Tel: 86-532-502-7355 Fax: 86-532-502-7205 Malaysia - Penang Tel:011-604-646-8870 Fax:011-604-646-5086 Singapore Tel: 65-6334-8870 Fax: 65-6334-8850 Italy - Milan Tel: 39-0331-742611 Fax: 39-0331-466781 Netherlands - Drunen Tel: 31-416-690399 Fax: 31-416-690340 England - Berkshire Tel: 44-118-921-5869 Fax: 44-118-921-5820 Taiwan - Kaohsiung Tel: 886-7-536-4818 Fax: 886-7-536-4803 Taiwan - Taipei Tel: 886-2-2500-6610 Fax: 886-2-2508-0102 Taiwan - Hsinchu Tel: 886-3-572-9526 Fax: 886-3-572-6459 Los Angeles Mission Viejo, CA Tel: 949-462-9523 Fax: 949-462-9608 San Jose Mountain View, CA Tel: 650-215-1444 Fax: 650-961-0286 Toronto Mississauga, Ontario, Canada Tel: 905-673-0699 Fax: 905-673-6509 04/20/05 DS41249B-page 182 Preliminary © 2005 Microchip Technology Inc.