Post by thread:[PIC]:What is the best way to end a program

For development purposes, I have tried two different approaches to ending a program Run the program to "end" or create an endless loop like "stop goto stop" I have noticed that sometimes my 16F877 will just suddenly re-boot or reset and re-run the program after it has been sitting in either a endless loop or sent to end. There are not any voltage spikes present on the circuit at the time of reset. Has anybody experienced this before? -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

WEBB,TIM (A-Sonoma,ex1) <spam_OUTPICLISTTakeThisOuTmitvma.mit.edu> wrote: > For development purposes, I have tried two different approaches to > ending a program > > Run the program to "end" or create an endless loop like "stop goto > stop" > > I have noticed that sometimes my 16F877 will just suddenly re-boot or > reset and re-run the program after it has been sitting in either a > endless loop or sent to end. Tim: What, exactly, does "run the program to 'end'" mean? If you're writing in assembly language, there's no such thing as an "end" instruction; the "end" line in your source code is used only be your assembler. Allowing your program to just run into it will cause the symptom you're seeing, since the PIC will keep executing the code in the "empty" code memory locations beyond the last location used by your code, until its program counter wraps around to the reset vector at 0000. If you want to terminate your program with "stop: goto stop", you'll need to ensure that the watchdog timer is disabled (or clear the watchdog timer inside the loop). This code will work: STOP: CLRWDT GOTO STOP -Andy === Andrew Warren -- .....aiwKILLspam@spam@cypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

WEBB,TIM (A-Sonoma,ex1) <PICLISTKILLspammitvma.mit.edu> wrote: > I have the watchdog timer set to OFF > > And my program is terminated using the following: > > stop goto stop If your previous statements about the stability of MCLR and Vdd are true, and PCLATH is set correctly for the "goto stop" (it probably is, especially if you got to the "stop" label via a goto in the first place), then the PIC will only execute code outside the "stop" loop if an interrupt occurs. Are interrupts disabled (or guaranteed to return)? -Andy === Andrew Warren -- .....aiwKILLspam.....cypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I am not using any interupts yet -----Original Message----- From: Andrew Warren [EraseMEaiwspam_OUTTakeThisOuTCYPRESS.COM] Sent: Thursday, February 07, 2002 1:42 PM To: PICLISTspam_OUTMITVMA.MIT.EDU Subject: Re: [PIC]:What is the best way to end a program WEBB,TIM (A-Sonoma,ex1) <@spam@PICLISTKILLspammitvma.mit.edu> wrote: > I have the watchdog timer set to OFF > > And my program is terminated using the following: > > stop goto stop If your previous statements about the stability of MCLR and Vdd are true, and PCLATH is set correctly for the "goto stop" (it probably is, especially if you got to the "stop" label via a goto in the first place), then the PIC will only execute code outside the "stop" loop if an interrupt occurs. Are interrupts disabled (or guaranteed to return)? -Andy === Andrew Warren -- KILLspamaiwKILLspamcypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

"WEBB,TIM (A-Sonoma,ex1)" wrote: > > I have the watchdog timer set to OFF > > And my program is terminated using the following: > > stop goto stop I know this sounds corny and shouldn't matter, but I use.. Stop nop goto Stop Weird things can fix weird problems :-) -- Best regards Tony mICros http://www.bubblesoftonline.com RemoveMEsalesTakeThisOuTbubblesoftonline.com -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

WEBB,TIM (A-Sonoma,ex1) <spamBeGonePICLISTspamBeGonemitvma.mit.edu> wrote: > > the PIC will only execute code outside the "stop" loop if an > > interrupt occurs. > > > > Are interrupts disabled (or guaranteed to return)? > > I am not using any interupts yet I believe you... But are interrupts disabled? -Andy === Andrew Warren -- TakeThisOuTaiwEraseMEspam_OUTcypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

I do not know for sure How do you disable interupts? I am still learning... -----Original Message----- From: Andrew Warren [RemoveMEaiwTakeThisOuTCYPRESS.COM] Sent: Thursday, February 07, 2002 4:34 PM To: PICLISTEraseME.....MITVMA.MIT.EDU Subject: Re: [PIC]:What is the best way to end a program WEBB,TIM (A-Sonoma,ex1) <EraseMEPICLISTmitvma.mit.edu> wrote: > > the PIC will only execute code outside the "stop" loop if an > > interrupt occurs. > > > > Are interrupts disabled (or guaranteed to return)? > > I am not using any interupts yet I believe you... But are interrupts disabled? -Andy === Andrew Warren -- RemoveMEaiwEraseMEEraseMEcypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

WEBB,TIM (A-Sonoma,ex1) <RemoveMEPICLISTspam_OUTKILLspammitvma.mit.edu> wrote: > How do you disable interupts? Make your "stop" code look like this: STOP: CLRWDT BCF INTCON,GIE GOTO STOP It's a good idea to keep the BCF inside the "stop" loop, as shown above, to help avoid the race condition that occurs if an interrupt is triggered while the BCF instruction is being executed. To avoid that potential problem entirely, do the above and also add the following code at the interrupt vector (address 0x04): ORG 0x04 RETURN If this doesn't solve your problem, you may have to go back and re-check your cornerstone assumptions (e.g., MCLR is high and stable, Vdd is high and stable, the PIC is actually getting to the "stop" code, etc.). -Andy === Andrew Warren -- RemoveMEaiwTakeThisOuTspamcypress.com === Principal Design Engineer === Cypress Semiconductor Corporation === === Opinions expressed above do not === necessarily represent those of === Cypress Semiconductor Corporation -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

For endless loops at the end of a program, or if I want an "infinite" delay during an interrupt-driven program, I use: goto $ at the end of my functional program. Note that you cannot use the assembler "END" statement as a program terminator. It's only used for the assembler itself to let it know there are no more instructions to process. If you do not REALLY terminate your program prior to this (with a SLEEP, for example), or keep it looping, it will act as a reset and start over at ORG 0x000. --Andrew _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

If you want to stop the pic dead issue a sleep instruction as the last instruction in the program, and maybe add a goto to this sleep instruction after it (in case there is a pending interrupt you do not expect). Peter -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

About the only sure way I've found to end a program consists of the following procedure: 1. Delete all files concerning it from your hard disk. 2. Use a program to wipe the disk to ensure they're gone. 3. Do the same with any floppies that ever may have held the code. 4. Shred all printed copies. 5. Burn the shredded paper. 6. Crush all devices into which the code may have been programmed. 7. Witness the crushed remains buried in landfill. 8. Change your name. 9. Move. Anything less and it will surely find you again. Gary Crowell > {Original Message removed}