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Hello, I experience some problems with a usual PIC-delay, written in assembler (with MPLAB IDE). I try to make a simple program wich toggles pin RA0. The program listed bellow is for a period(!) of +/- 6,5ms (but actually it doesn't mather I guess). When I connect my oscilloscope at pin RA0, I can see the squarewave, but at regulier times (every second or 2) there is a little spike (going low). I don't know how it got there. When I make the delay longer (0,5s for example), I have a simmilar problem: RA0 goes high for 0,5s, back to low for 0,5s, back to high for 0,5s and then there is a very small time that RA0 goes low (only vissible at scope). After this very short time, RA0 is back high for 0,5s and the process continues. And I didn't program it that way (or that's what I think). Can someboby pls take a look at my code below (sorry, comments are in dutch)? Thx in advance, Matti, Belgium status equ 03h ;statusregister porta equ 05h ;poortA trisa equ 05h ;poortA input/output register portb equ 06h ;poortB trisb equ 06h ;poortB input/output register delay1 equ 0ch delay2 equ 0dh delay3 equ 0eh #define rp0 status,5 ;rp0 = bit5 statusreg start org 05h call portdir ;poortA & B directions bcf rp0 ;bank0 selecteren ;HOOFDPROGRAMMA ;-------------- main bsf porta,0 ;uitgang RA0 aan call delay ;vertraging oproepen bcf porta,0 ;uitgang RA0 uit call delay ;vertraging oproepen goto main ;DELAY SUBROUTINE ;---------------- delay movlw b'00001010' movwf delay1 del1 movlw b'00001010' movwf delay2 del2 movlw b'00001010' movwf delay3 del3 decfsz delay3,f ;vertraging goto del3 decfsz delay2,f goto del2 decfsz delay1,f goto del1 return ;POORT-INITIALISATIES ;-------------------- portdir bsf rp0 ;bank1 selecteren movlw b'00000001' ;poortB in/out movwf trisb movlw b'00010000' ;poortA in/out movwf trisa return end |
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PIC assembler delay
Started by ●September 1, 2003
Reply by ●September 1, 20032003-09-01
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Hello, I experience some problems with a usual PIC-delay, written in assembler (with MPLAB IDE). I try to make a simple program wich toggles pin RA0. The program listed bellow is for a period(!) of +/- 6,5ms (but actually it doesn't mather I guess). When I connect my oscilloscope at pin RA0, I can see the squarewave, but at regulier times (every second or 2) there is a little spike (going low). I don't know how it got there. When I make the delay longer (0,5s for example), I have a simmilar problem: RA0 goes high for 0,5s, back to low for 0,5s, back to high for 0,5s and then there is a very small time that RA0 goes low (only vissible at scope). After this very short time, RA0 is back high for 0,5s and the process continues. And I didn't program it that way (or that's what I think). Can someboby pls take a look at my code below (sorry, comments are in dutch)? Thx in advance, Matti, Belgium status equ 03h ;statusregister porta equ 05h ;poortA trisa equ 05h ;poortA input/output register portb equ 06h ;poortB trisb equ 06h ;poortB input/output register delay1 equ 0ch delay2 equ 0dh delay3 equ 0eh #define rp0 status,5 ;rp0 = bit5 statusreg start org 05h call portdir ;poortA & B directions bcf rp0 ;bank0 selecteren ;HOOFDPROGRAMMA ;-------------- main bsf porta,0 ;uitgang RA0 aan call delay ;vertraging oproepen bcf porta,0 ;uitgang RA0 uit call delay ;vertraging oproepen goto main ;DELAY SUBROUTINE ;---------------- delay movlw b'00001010' movwf delay1 del1 movlw b'00001010' movwf delay2 del2 movlw b'00001010' movwf delay3 del3 decfsz delay3,f ;vertraging goto del3 decfsz delay2,f goto del2 decfsz delay1,f goto del1 return ;POORT-INITIALISATIES ;-------------------- portdir bsf rp0 ;bank1 selecteren movlw b'00000001' ;poortB in/out movwf trisb movlw b'00010000' ;poortA in/out movwf trisa return end |
Reply by ●September 1, 20032003-09-01
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Are you certain you have the watch dog timer turned off? It will do a PIC reset periodically. --- In , "Matti Laevaert" <matti.laevaert@w...> wrote: > Hello, > > I experience some problems with a usual PIC-delay, written in > assembler (with MPLAB IDE). > I try to make a simple program wich toggles pin RA0. The program > listed bellow is for a period(!) of +/- 6,5ms (but actually it > doesn't mather I guess). When I connect my oscilloscope at pin RA0, > I can see the squarewave, but at regulier times (every second or 2) > there is a little spike (going low). I don't know how it got there. > When I make the delay longer (0,5s for example), I have a simmilar > problem: RA0 goes high for 0,5s, back to low for 0,5s, back to high > for 0,5s and then there is a very small time that RA0 goes low (only > vissible at scope). After this very short time, RA0 is back high for > 0,5s and the process continues. And I didn't program it that way (or > that's what I think). > > Can someboby pls take a look at my code below (sorry, comments are > in dutch)? > > Thx in advance, > Matti, Belgium > > status equ 03h ;statusregister > porta equ 05h ;poortA > trisa equ 05h ;poortA input/output register > portb equ 06h ;poortB > trisb equ 06h ;poortB input/output register > delay1 equ 0ch > delay2 equ 0dh > delay3 equ 0eh > #define rp0 status,5 ;rp0 = bit5 statusreg > start > org 05h > call portdir ;poortA & B > directions > bcf rp0 ;bank0 selecteren > > ;HOOFDPROGRAMMA > ;-------------- > > main > bsf porta,0 ;uitgang RA0 aan > call delay ;vertraging oproepen > bcf porta,0 ;uitgang RA0 uit > call delay ;vertraging oproepen > goto main > > ;DELAY SUBROUTINE > ;---------------- > > delay > movlw b'00001010' > movwf delay1 > del1 > movlw b'00001010' > movwf delay2 > del2 > movlw b'00001010' > movwf delay3 > del3 > decfsz delay3,f ;vertraging > goto del3 > decfsz delay2,f > goto del2 > decfsz delay1,f > goto del1 > return > > ;POORT-INITIALISATIES > ;-------------------- > > portdir > bsf rp0 ;bank1 selecteren > movlw b'00000001' ;poortB in/out > movwf trisb > movlw b'00010000' ;poortA in/out > movwf trisa > return > > end |
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Reply by ●September 1, 20032003-09-01
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Yes it was the watchdog, I already found it. :-) Thx anyway! Matti --- In , "rtstofer" <rstofer@p...> wrote: > > Are you certain you have the watch dog timer turned off? It will do > a PIC reset periodically. > > --- In , "Matti Laevaert" > <matti.laevaert@w...> wrote: > > Hello, > > > > I experience some problems with a usual PIC-delay, written in > > assembler (with MPLAB IDE). > > I try to make a simple program wich toggles pin RA0. The program > > listed bellow is for a period(!) of +/- 6,5ms (but actually it > > doesn't mather I guess). When I connect my oscilloscope at pin RA0, > > I can see the squarewave, but at regulier times (every second or 2) > > there is a little spike (going low). I don't know how it got there. > > When I make the delay longer (0,5s for example), I have a simmilar > > problem: RA0 goes high for 0,5s, back to low for 0,5s, back to high > > for 0,5s and then there is a very small time that RA0 goes low > (only > > vissible at scope). After this very short time, RA0 is back high > for > > 0,5s and the process continues. And I didn't program it that way > (or > > that's what I think). > > > > Can someboby pls take a look at my code below (sorry, comments are > > in dutch)? > > > > Thx in advance, > > Matti, Belgium > > > > > > > > status equ 03h ;statusregister > > porta equ 05h ;poortA > > trisa equ 05h ;poortA input/output register > > portb equ 06h ;poortB > > trisb equ 06h ;poortB input/output register > > delay1 equ 0ch > > delay2 equ 0dh > > delay3 equ 0eh > > #define rp0 status,5 ;rp0 = bit5 > statusreg > > > > > > > > start > > org 05h > > call portdir ;poortA & B > > directions > > bcf rp0 ;bank0 selecteren > > > > ;HOOFDPROGRAMMA > > ;-------------- > > > > main > > bsf porta,0 ;uitgang RA0 aan > > call delay ;vertraging oproepen > > bcf porta,0 ;uitgang RA0 uit > > call delay ;vertraging oproepen > > goto main > > > > ;DELAY SUBROUTINE > > ;---------------- > > > > delay > > movlw b'00001010' > > movwf delay1 > > del1 > > movlw b'00001010' > > movwf delay2 > > del2 > > movlw b'00001010' > > movwf delay3 > > del3 > > decfsz delay3,f ;vertraging > > goto del3 > > decfsz delay2,f > > goto del2 > > decfsz delay1,f > > goto del1 > > return > > > > ;POORT-INITIALISATIES > > ;-------------------- > > > > portdir > > bsf rp0 ;bank1 selecteren > > movlw b'00000001' ;poortB in/out > > movwf trisb > > movlw b'00010000' ;poortA in/out > > movwf trisa > > return > > > > end |
Reply by ●September 1, 20032003-09-01
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At 09:11 AM 9/1/2003, Matti Laevaert wrote: >Hello, > >I experience some problems with a usual PIC-delay, written in >assembler (with MPLAB IDE). >I try to make a simple program wich toggles pin RA0. The program >listed bellow is for a period(!) of +/- 6,5ms (but actually it >doesn't mather I guess). When I connect my oscilloscope at pin RA0, >I can see the squarewave, but at regulier times (every second or 2) >there is a little spike (going low). Have you disabled the watchdog timer? If not, this may cause the symptoms you mention. Something to try: add some 'clrwdt' instructions to your code such that a clrwdt happens at least every 5ms or so (assuming prescaler is assigned to TMR0). dwayne -- Dwayne Reid <> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 19 years of Engineering Innovation (1984 - 2003) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. |
