Try

;
; ------------------------------
; SET ANALOG INPUTS = DIGITAL IO
; ------------------------------
;
        movlw b'00001110'
        movwf ADCON1


James De Leon wrote:
>
> I am having difficulty writing bits to PORTA on a PIC16F877.  For some
> reason, even after setting the TRISA bits low (output) I cannot write to
> PORTA <3:0>.  I can,  however, write to PORTA<5:4>.  I am fully aware of
> bank switching and I don't have any problems with writing bits to
> PORTB<7:0> or to PORTD<7:0>
>
> Here is a simple program I wrote to initialize PORTA and PORTB as
> output:
>
>      __CONFIG _PWRTE_ON & _XT_OSC & _WDT_OFF
>     clrf    STATUS
>     clrf    PORTA
>     clrf    PORTB
>     bsf    STATUS, RP0
>     movlw    b'00000000'
>     movwf    TRISA
>     movwf    TRISB
>     bcf    STATUS, RP0
>     movlw    b'11111111'
>     movwf    PORTA
>     movwf    PORTB
>     end
>
> In this code, a write of the bitfield '11111111' to PORTB does just
> that.  After the code is executed, I expect PORTA to be '00111111' (Bits
> 7 and 6 are unimplemented) but it just stays at '00000000'.  Has anyone
> encountered the same problem?  Is there something I am doing wrong?
> This has been very frustrating for me.  Any help or suggestions would be
> wonderful.
>
> By the way, I simulated this with MPLAB 5.70.00
>
> Thank you,
> James
>
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--
Best regards

Tony

mICros
http://www.bubblesoftonline.com
mailto:sales@bubblesoftonline.com

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