On Wed, 12 Jun 2002, Guillermo Rodriguez Garcia wrote:

>
> I've searched the archive in www.piclist.com but all ADC code I
> can find always uses 8-bit results only, configuring the ADC to
> be left-justified and neglecting the ADRESL register.

How ? this is a slighty adjusted copy from your code:

     bank0
     movf    ADRESH, W           ; get the 8 MSBs
     movwf   adc_high
     bsf     STATUS, RP0         ; Bank1
     movf    ADRESL, W           ; get the 2 MSBs
     bcf     STATUS, RP0         ; Bank0 -- here
     movwf   adc_low
   ;  bcf     STATUS, RP0         ; Bank0  -- and not here !


one Jal version:

procedure ch_write is
  delay_10uS ( 2 )               -- wait min aquisition time
  adcon0_go = high               -- start conversion
  while adcon0_go loop end loop  -- wait for ad completion
  ch_hi = f877_adresh
  bank_1
  asm  movf    f877_adresl,w
  bank_0
  asm  movwf   ch_lo
end procedure

Vasile










>
> Has anyone found this problem before? Any hints?
>
> Code follows:
>
> === Cut ===
>
> Startup
>      bsf     STATUS, RP0         ; Bank1
>      movlw   b'11111111'         ; PORT A = all inputs
>      movwf   TRISA
>      clrf    TRISC               ; PORT C = all outputs
>
>      bcf     STATUS, RP0         ; Bank0
>      movlw   b'01000001'         ; Fosc/8, A/D enabled
>      movwf   ADCON0
>
>      bsf     STATUS, RP0         ; Bank1
>      movlw   b'00001110'         ; Left justify, 1 analog channel
>      movwf   ADCON1              ; VDD and VSS references
>
>      movlw   b'10000111'         ; TMR0, 1:256
>      movwf   OPTION_REG
>
>      bcf     STATUS, RP0         ; go back to Bank0
>
> Main
>      ;
>      ; acquisition time before starting the AD conversion
>      ;
>      clrf    TMR0                ; ensures that we start a complete T0
> cycle here
>      bcf     INTCON,T0IF
> _T0Wait
>      btfss   INTCON,T0IF         ; wait for Timer0 to timeout
>      goto    _T0Wait
>      bcf     INTCON,T0IF
>
>      ;
>      ; starts the AD conversion
>      ;
>      bsf     ADCON0,GO           ; start A/D conversion
> _waitAdc
>      btfss   PIR1, ADIF          ; conversion complete?
>      goto    _waitAdc            ; = NO (wait)
>
>      bcf     PIR1, ADIF          ; clear conversion complete flag
>
>      movf    ADRESH, W           ; get the 8 MSBs
>      movwf   adc_high
>      bsf     STATUS, RP0         ; Bank1
>      movf    ADRESL, W           ; get the 2 MSBs
>      movwf   adc_low
>      bcf     STATUS, RP0         ; Bank0
>
>      goto    Main                ; Loop forever
> === Cut ===
>
>
> Thanks,
> G.
>
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>

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