On Mon, 17 Nov 2003 21:54, you wrote:
> Hi Phil,
> So far, so good.
>
> >Start           btfsc   PORTA, 1                ;wait for a.1 to ground
> >                goto            Start
> >
> >                movlw   04h                     ;Turn on the LED
> >                movwf   PORTA
> >
> >                goto            Start
>
> OK, change it to this:
>
> start:          btfss   PORTA,1                 ;is RA.1 high?
>                 goto    sw_low                  ;no
>                 movlw   04h                     ;yes
>                 movwf   PORTA                   ;turn LED on
>                 goto    start                   ;
>
> sw_low:         clrf    PORTA                   ;turn LED off (this is the
> step you forgot!) goto    start                   ;
>

Thank you for the help so far. Unfortunately now the LED does not turn on, the
reverse of what I had originally.

I had, and still have a 10k pull-up resistor connected to pin 18 (RA 1) and
have added "org 0" to the source file. Powering up the PIC with pin 18 in a
high or low state has no effect, just as grounding the pin after power-up has
no effect.

I'm still missing something and I'm sure it's something basic. Maybe something
to do with power-on reset?

By the way, the layout of my code looks OK here. It must be another one of
those problems with the "other" OS.

--
Regards,
Phil.

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