TIMER1 MODULE Timer1 Module Data Sheet Errata Clarifications/Corrections to the Data Sheet: In the Device data sheets listed below, the following clarifications and corrections should be noted. Any silicon issues related to the Timer1 Module will be reported in a separate silicon errata. Please check the Microchip web site for any existing issues. Device Data Sheet Device PIC12F609 PIC16F716 PIC12HV609 PIC16F737 PIC12F615 DS41302 PIC12HV615 PIC12F629 PIC12F675 DS41190 PIC12F635 PIC16F636 PIC16F785 DS41232 PIC16F818 PIC16F819 PIC12F683 DS41211 PIC16F870 PIC14000 DS40122 PIC16F871 PIC16C62A PIC16F872 PIC16C63 PIC16F873 PIC16C64A PIC16C65A DS30234 PIC16F874 PIC16F876 Device PIC18F2321 PIC18F4321 Data Sheet DS39689 PIC18F2331 DS30498 PIC16F777 PIC16HV785 PIC16F639 DS41206 PIC16F747 PIC16F767 PIC12F617 Data Sheet DS41249 DS39598 DS30569 DS30221 PIC18F2431 PIC18F6585 PIC18F6680 PIC18F8585 DS39616 PIC18F24J10 PIC18F4431 PIC18F25J10 PIC18F2439 PIC18F44J10 PIC18F2539 PIC18F4439 DS30485 PIC18F45J10 PIC18F4539 PIC18F64J11 PIC18F65J11 PIC18F2550 PIC18F83J11 PIC18F4550 PIC18F85J11 PIC18F63J90 PIC16C66 PIC16F877 PIC18F4480 PIC16C67 PIC16F873A PIC18F4580 PIC18F65J90 PIC16C62B PIC16F874A PIC18F2510 PIC18F83J90 PIC16C72A DS35008 PIC16F876A DS39582 PIC18F2610 PIC16C63A PIC16F877A PIC18F4510 PIC16C65B PIC16F882 PIC18F4610 PIC16C73B DS30605 PIC16F883 PIC18F2520 PIC16C74B PIC16F884 PIC16C72 PIC16F886 PIC18F2585 PIC16C73A PIC16F887 PIC18F2680 PIC16F913 PIC18F4585 PIC16F914 PIC18F4680 PIC16C74A DS30390 PIC16C76 PIC16C77 PIC16F916 PIC16C745 PIC16F917 PIC16C765 DS41124 PIC16F946 2010 Microchip Technology Inc. DS41291 DS41250 PIC18F4520 PIC18F2620 PIC18F4620 DS39636 DS39774 PIC18F84J11 PIC18F2480 DS39637 DS39682 PIC18F63J11 PIC18F2455 DS39632 DS30491 PIC18F8680 PIC18F4331 PIC18F4455 DS30292 Data Sheet Device PIC18F64J90 DS39770 PIC18F84J90 PIC18F85J90 PIC18F65J10 DS39631 PIC18F65J15 PIC18F66J10 PIC18F66J15 DS39625 PIC18F67J10 PIC18F85J10 DS39663 PIC18F85J15 DS39626 PIC18F86J10 PIC18F85J15 PIC18F87J10 DS80329B-page 1 TIMER1 MODULE Device PIC16C773 PIC16C774 PIC16C923 PIC16C924 PIC16C925 PIC16C926 PIC16F72 Data Sheet DS30275 DS30444 DS39544 DS39597 Device Data Sheet PIC17C42A PIC17C43 Device PIC18F4685 PIC18F66J50 PIC18F66J55 PIC17C752 PIC18F8390 PIC17C756A PIC18F8490 DS30289 PIC17C766 PIC18F85J55 PIC18F87J50 PIC18F6720 PIC18F8520 PIC16F87 PIC16F88 PIC18C452 DS30487 PIC18C601 PIC18C801 PIC16F610 PIC18C658 PIC16HV610 PIC18C858 PIC16F616 DS39026 DS41288 DS39541 DS30475 PIC18F67J50 DS39609 PIC18F66J11 PIC18F67J11 PIC18F8720 PIC18F86J11 PIC18F6525 PIC18F86J16 PIC18F6621 PIC18F87J11 DS39612 PIC18F8621 PIC18F66J60 PIC18F242 PIC18F6527 PIC18F67J60 PIC18F252 PIC18F6622 PIC18F86J60 PIC16F627A PIC18F442 PIC18F6627 PIC18F86J65 PIC18F452 PIC18F6722 PIC18F87J60 PIC16F648A PIC18F248 PIC18F8527 PIC16F630 PIC18F258 PIC16F628A PICF676 DS40044 DS40039 DS41159 PIC18F97J60 PIC18F458 PIC18F8627 PIC18F8722 PIC16F677 PIC18F1320 PIC16F685 PIC16F687 DS41262 PIC16F689 PIC18F1230 PIC18F1330 DS39758 PIC18F2220 PIC16F690 PIC18F2330 PIC16F684 DS41202 PIC18F4220 PIC16F688 DS41203 PIC18F4320 DS80329B-page 2 DS39762 PIC18F96J60 PIC18F96J65 PIC18F1220 DS39605 DS39646 PIC18F8622 PIC16F631 DS39778 PIC18F66J65 PIC16HV616 DS39564 DS39775 PIC18F66J16 PIC18F8620 PIC18F8525 Data Sheet PIC18F85J50 PIC18F6620 PIC18C242 PIC18C442 DS39629 PIC18F6520 PIC18C252 PIC16F77 PIC18F65J50 PIC18F6390 PIC16F74 DS30325 DS39761 PIC18F6490 PIC16F73 PIC16F76 Device PIC17C44 PIC17C762 DS30412 Data Sheet DS39599 2010 Microchip Technology Inc. TIMER1 MODULE 1. Asynchronous Counter When Timer1 is started or updated, the timer needs to see a falling edge from the external clock source before a rising edge can increment the counter. If writes to TMR1H and TMR1L are not completed while the external clock pulse is still high, Timer1 will miss counting the first clock pulse after the update. When using an external crystal, the pulse width from rising to falling edge is temperature dependent and may decrease with temperature. As a result, the timer may require an additional oscillation to overflow. Code examples are given for the affected devices: * PIC12/14/16/17 devices - Example 1 and Example 2 * PIC18 devices - Example 3 Both examples include code to wait for Timer1 to increment twice between the RTCisr and Update labels. EXAMPLE 1: BTFSC GOTO BTFSS GOTO In PIC18 devices, it is not possible to reliably update Timer1 in a low-priority interrupt. A highpriority interrupt could occur at any time and unexpectedly delay the TMR1 update. PIC18 devices also include Timer3 which is functionally identical to Timer1. Work around Switching Timer1 to the main system oscillator after reloading, the timer ensures the timer will see a falling edge before switching back to the external clock source. Due to the time from Timer1 overflow to the reload being application specific, wait for the timer to increment before beginning the reload sequence. This ensures the timer does not miss a rising edge during reload. The timing of the clock source changing is critical and is detailed in Example 1 and Example 2. PIC12/14/16/17 CODE EXAMPLE FOR 1 SECOND OVERFLOW PERIOD WITH 32.786 kHZ OSCILLATOR TMR1L,0 $-1 TMR1L,0 $-1 ;Timer has just incremented, 31 s before next rising edge to ;complete reload Update: BCF BSF BCF BSF BSF T1CON,TMR1CS TMR1H,7 T1CON,TMR1ON T1CON,TMR1C T1CON,TMR1ON ;Select ;Timer1 ;Timer1 ;Select ;Timer1 system clock for Timer1 high byte 0x80 off external crystal on Critical Timing of code sequence for instructions following last write to TMR1L or TMR1H. 2010 Microchip Technology Inc. DS80329B-page 3 TIMER1 MODULE EXAMPLE 2: PIC12/14/16/17 CODE EXAMPLE FOR OVERFLOW PERIODS OTHER THAN 1 SECOND OR USING AN OSCILLATOR OTHER THAN 32.768 kHZ BTFSC GOTO BTFSS GOTO TMR1L, 0 $-1 TMR1L, 0 $-1 ;Timer has just incremented, 31s before next rising edge to complete reload. BCF MOVF ADDWF BTFSC INCF T1CON, TMR1CS TMR1, W TMR1_Reload_lo, F STATUS, C TMR1_Reload_hi, F ;Select system clock for Timer1. ;Sample low byte of Timer1 before increments. ;Add reload value for low byte ;if this generates a carry then ;modify the reload value for the high byte. MOVF MOVWF TMR1_Reload_hi, W TMR1H ;Reload Timer1 high byte. MOVF MOVW TMR1_Reload_lo, W TMR1L ;Reload Timer1 low byte. BCF BSF BSF T1CON, TMR1ON T1CON, TMR1CS T1CON, TMR1ON ;Timer1 off. ;Select external crystal. ;Timer1 on. Critical Timing of code sequence for instructions. EXAMPLE 3: PIC18 HIGH-PRIORITY INTERRUPT SERVICE ROUTINE HIntVector code 0x0008 goto HighISR HighISR: btfss goto ; ; (3-4Tcy), fixed interrupt latency (3Tcy) jump to high priority ISR code code ; unprotected code space PIR1,TMR1IF NextISR ; ; (1Tcy) TMR1 overflow? (2Tcy) No, check another interrupt source ; Insert the next 4 lines of ; be reliably updated before RTCisr: btfsc TMR1L,0 ; bra $-2 ; btfss TMR1L,0 ; bra $-2 ; code when TMR1 can not clock pulse goes low wait for TMR1L<0> to become clear may already be clear (loops for 0 to 30.5us) wait for TMR1L<0> to become set (loops for 30.5us) ; If TMR1 update can be completed before clock pulse ; goes low, start update here Update: bsf TMR1H,7 ; reload for next 1 second overflow bcf PIR1,TMR1IF ; clear flag incf Seconds,F ; record second retfie FAST NextISR: .... ; ; Another interrupt source... code for other interrupts, if needed retfieFAST DS80329B-page 4 2010 Microchip Technology Inc. TIMER1 MODULE REVISION HISTORY Rev A Document (7/2007) Initial release of this errata. Rev B Document (03/2010) Added PIC12F617 device to the Clarifications/ Corrections to the Data Sheet section. 2010 Microchip Technology Inc. DS80329B-page 5 TIMER1 MODULE NOTES: DS80329B-page 6 2010 Microchip Technology Inc. Note the following details of the code protection feature on Microchip devices: * Microchip products meet the specification contained in their particular Microchip Data Sheet. * Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. * There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. * Microchip is willing to work with the customer who is concerned about the integrity of their code. * Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as "unbreakable." Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip's code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer's risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, dsPIC, KEELOQ, KEELOQ logo, MPLAB, PIC, PICmicro, PICSTART, PIC32 logo, rfPIC and UNI/O are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. FilterLab, Hampshire, HI-TECH C, Linear Active Thermistor, MXDEV, MXLAB, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. Analog-for-the-Digital Age, Application Maestro, CodeGuard, dsPICDEM, dsPICDEM.net, dsPICworks, dsSPEAK, ECAN, ECONOMONITOR, FanSense, HI-TIDE, In-Circuit Serial Programming, ICSP, Mindi, MiWi, MPASM, MPLAB Certified logo, MPLIB, MPLINK, mTouch, Octopus, Omniscient Code Generation, PICC, PICC-18, PICDEM, PICDEM.net, PICkit, PICtail, REAL ICE, rfLAB, Select Mode, Total Endurance, TSHARC, UniWinDriver, WiperLock and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. (c) 2010, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. ISBN: 978-1-60932-048-5 Microchip received ISO/TS-16949:2002 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company's quality system processes and procedures are for its PIC(R) MCUs and dsPIC(R) DSCs, KEELOQ(R) code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip's quality system for the design and manufacture of development systems is ISO 9001:2000 certified. 2010 Microchip Technology Inc. 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