Post by thread:First Project with PIC16F87x doesn't work

Hi All, My first project with the PIC16F87X doesn't work. I am simply trying to do a conversion A/D in the PORTA0 and show it in PORTB with leds.Also a led blinking in the PORTC6 using TMRO overflow. I'm using a 4MHZ cristal. See my Codes below. #DEFINE LED PORTC6 list p=16f873 include "p16f873.inc" __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _XT_OSC & _WRT_ENABLE_OFF ;---------------------------------------------------- ; Start at the reset vector org 0x000 Start: clrf PORTA clrf PORTB clrf PORTC bsf STATUS,RP0 movlw B'00000111' ;TMR0 prescaler, 1:256 movwf OPTION_REG movlw b'00000001' ;PA0=IN movwf TRISA movlw b'00000000' movwf TRISB ;PB=OUT movlw b'00000000' ;PC=OUT movwf TRISC movlw b'00001110' ;VREF+ VDD E VREF- VSS, PORTA0 A/D IN movwf ADCON1 bcf STATUS,RP0 ;Fosc/8, A/D ON movlw b'01000001' movwf ADCON0 MAIN: clrf TMR0 btfss INTCON,T0IF ;Wait for Timer0 to timeout goto $-1 bcf INTCON,T0IF btfss LED goto LED_ON bcf LED goto SET_AD LED_ON: bsf LED SET_AD: bsf ADCON0,GO ;Start A/D conversion Wait: btfss PIR1,ADIF ;Wait for conversion to complete goto $-1 movf ADRESH,W ;Write A/D result to PORTB movwf PORTB goto MAIN I would appreciate it if someone could make a suggestion. Thanks in advanced. Anbar.

anbarsystem@ZAZ.COM.BR wrote: > > Hi All, > My first project with the PIC16F87X doesn't work. I am simply trying to do a > conversion A/D in the PORTA0 and show it in PORTB with leds.Also a led > blinking in the PORTC6 using TMRO overflow. I'm using a 4MHZ cristal. > > See my Codes below. > > #DEFINE LED PORTC6 > > list p=16f873 > > include "p16f873.inc" > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _XT_OSC & > _WRT_ENABLE_OFF > Add this.. Temp equ 20h ; temp timer register {Quote hidden}> ;---------------------------------------------------- > ; Start at the reset vector > org 0x000 > > Start: > clrf PORTA > clrf PORTB > clrf PORTC > bsf STATUS,RP0 > movlw B'00000111' ;TMR0 prescaler, 1:256 > movwf OPTION_REG > movlw b'00000001' ;PA0=IN > movwf TRISA > movlw b'00000000' > movwf TRISB ;PB=OUT > movlw b'00000000' ;PC=OUT > movwf TRISC Try this value for ADCON1 movlw b'00000100' ; RA0,1,3 = A2D, left justify > movlw b'00001110' ;VREF+ VDD E VREF- VSS, PORTA0 A/D IN > movwf ADCON1 > bcf STATUS,RP0 ;Fosc/8, A/D ON Try this value for ADCON0 movlw b'11000001' ; A2D = on, internal RC, chan 0 > movlw b'01000001' > movwf ADCON0 > The LED may appear not to blink because the time it takes for TMR0 to overflow at 4MHz is about 65mS. Try this... > MAIN: movlw d'10' movwf Temp > clrf TMR0 TimeWt btfss INTCON,T0IF ;Wait for Timer0 to timeout > goto $-1 > bcf INTCON,T0IF decfsz Temp goto TimeWt {Quote hidden}> btfss LED > goto LED_ON > bcf LED > goto SET_AD > > LED_ON: > bsf LED > > SET_AD: > bsf ADCON0,GO ;Start A/D conversion > Try this code for conversion complete Wait nop btfsc ADCON0,GO ; (bit 2) = 0, conv is complete goto Wait {Quote hidden}> Wait: > btfss PIR1,ADIF ;Wait for conversion to complete > goto $-1 > > movf ADRESH,W ;Write A/D result to PORTB > movwf PORTB > goto MAIN > > I would appreciate it if someone could make a suggestion. > > Thanks in advanced. > Anbar. -- Best regards Tony http://www.picnpoke.com spam_OUTsalesTakeThisOuTpicnpoke.com

One reason I've seen for F87X's not working right away is the Low Voltage Programming (LVP) enable bit in the configuration word. It defaults to enabled, which takes away RB3 as an I/O pin. I only looked at enough of your code to see that LVP wasn't disabled. You don't say exactly what the problem is, but if RB3 is mysteriously not reacting properly, this would explain it. Set configuration word bit 7 = 0. --- .....anbarsystemKILLspam@spam@ZAZ.COM.BR wrote: {Quote hidden}> Hi All, > My first project with the PIC16F87X doesn't work. I > am simply trying to do a > conversion A/D in the PORTA0 and show it in PORTB > with leds.Also a led > blinking in the PORTC6 using TMRO overflow. I'm > using a 4MHZ cristal. > > See my Codes below. > > #DEFINE LED PORTC6 > > list p=16f873 > > include "p16f873.inc" > > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & > _PWRTE_OFF & _XT_OSC & > _WRT_ENABLE_OFF > <snip> __________________________________________________ Do You Yahoo!? Talk to your friends online with Yahoo! Messenger. http://im.yahoo.com

Hi Tony, thanks for your attention. My doubts it is: Will it be that my initial configuration this correct one? __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _XT_OSC & _WRT_ENABLE_OFF The led realy doesn't blink. I put on the osciloscope in the out (PORTC6), and nothing doesn't happen, it just is in 0. I am using PICSTART PLUS for play the PIC16F873. Regards. Anbar. {Quote hidden}> -----Mensagem Original----- > De: Tony Nixon <Tony.NixonKILLspamENG.MONASH.EDU.AU> > Para: <.....PICLISTKILLspam.....MITVMA.MIT.EDU> > Enviada em: Segunda-feira, 7 de Fevereiro de 2000 20:03 > Assunto: Re: First Project with PIC16F87x doesn't work > > > > EraseMEanbarsystemspam_OUTTakeThisOuTZAZ.COM.BR wrote: > > > > > > Hi All, > > > My first project with the PIC16F87X doesn't work. I am simply trying to > do a > > > conversion A/D in the PORTA0 and show it in PORTB with leds.Also a led {Quote hidden}> > > blinking in the PORTC6 using TMRO overflow. I'm using a 4MHZ cristal. > > > > > > See my Codes below. > > > > > > #DEFINE LED PORTC6 > > > > > > list p=16f873 > > > > > > include "p16f873.inc" > > > > > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_OFF & _XT_OSC {Quote hidden}> & > > > _WRT_ENABLE_OFF > > > > > > > Add this.. > > > > Temp equ 20h ; temp timer register > > > > > > > ;---------------------------------------------------- > > > ; Start at the reset vector > > > org 0x000 > > > > > > Start: > > > clrf PORTA > > > clrf PORTB > > > clrf PORTC > > > bsf STATUS,RP0 > > > movlw B'00000111' ;TMR0 prescaler, 1:256 > > > movwf OPTION_REG > > > movlw b'00000001' ;PA0=IN > > > movwf TRISA > > > movlw b'00000000' > > > movwf TRISB ;PB=OUT > > > movlw b'00000000' ;PC=OUT > > > movwf TRISC > > > > Try this value for ADCON1 > > > > movlw b'00000100' ; RA0,1,3 = A2D, left justify > > > > > movlw b'00001110' ;VREF+ VDD E VREF- VSS, PORTA0 A/D IN > > > movwf ADCON1 > > > bcf STATUS,RP0 ;Fosc/8, A/D ON > > > > Try this value for ADCON0 > > > > movlw b'11000001' ; A2D = on, internal RC, chan 0 > > > > > movlw b'01000001' > > > movwf ADCON0 > > > > > > > > > The LED may appear not to blink because the time it takes for TMR0 to > > overflow at 4MHz is about 65mS. Try this... > > > > > MAIN: > > movlw d'10' > > movwf Temp > > > clrf TMR0 > > TimeWt btfss INTCON,T0IF ;Wait for Timer0 to timeout > > > goto $-1 > > > bcf INTCON,T0IF > > > > decfsz Temp > > goto TimeWt > > > > > btfss LED > > > goto LED_ON > > > bcf LED > > > goto SET_AD > > > > > > LED_ON: > > > bsf LED > > > > > > SET_AD: > > > bsf ADCON0,GO ;Start A/D conversion > > > > > > > Try this code for conversion complete > > > > Wait nop > > btfsc ADCON0,GO ; (bit 2) = 0, conv is complete > > goto Wait > > > > > Wait: > > > btfss PIR1,ADIF ;Wait for conversion to complete > > > goto $-1 > > > > > > movf ADRESH,W ;Write A/D result to PORTB > > > movwf PORTB > > > goto MAIN > > > > > > I would appreciate it if someone could make a suggestion. > > > > > > Thanks in advanced. > > > Anbar. > > > > -- > > Best regards > > > > Tony > > > > http://www.picnpoke.com > > salesspam_OUTpicnpoke.com >

----- Original Message ----- From: <@spam@anbarsystemKILLspamZAZ.COM.BR> To: <KILLspamPICLISTKILLspamMITVMA.MIT.EDU> Sent: Monday, February 07, 2000 11:00 AM Subject: First Project with PIC16F87x doesn't work > Hi All, > My first project with the PIC16F87X doesn't work. I am simply trying to do a > conversion A/D in the PORTA0 and show it in PORTB with leds.Also a led > blinking in the PORTC6 using TMRO overflow. I'm using a 4MHZ cristal. I can't offer much advice on getting your particular code to work but since I'm new to pics as well and I was using the 16F876, the demo A/D code I finally got working after much struggle should work for you to get you started at least. I didn't use a crystal for my test, just the external RC connection, but I did get my program to do A/D on port A0 and show the left justified highest 8 bits on port B if you can use it at all. I modified a demo file that came wth MPlab for the 877 chip and here's my result: ;********************************************************** ;* This program configures the A/D Module to convert on ;* A/D channel 0 and display the results on the LEDS on PORTC. ;* Code modified from MPlab demo file for experimental use ;********************************************************** list p=16f876 include "p16f876.inc" org 0x000 nop Start banksel PORTC clrf PORTC ;Clear PORTC movlw B'11000001' ;RC, A/D enabled movwf ADCON0 banksel OPTION_REG movlw B'10000111' ;TMR0 prescaler, 1:256 movwf OPTION_REG clrf TRISC ;PORTC all outputs movlw B'00001110' ;Left justify,1 analog channel movwf ADCON1 ;VDD and VSS references banksel PORTC Main bsf ADCON0,GO ;Start A/D conversion Wait btfss PIR1,ADIF ;Wait for conversion to complete goto Wait movf ADRESH,W ;Write A/D result to PORTC movwf PORTC goto Main ;Do it again end