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


> ;----------------------------------------------------
> ; 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
mailto:sales@picnpoke.com