On Mon, 19 Jan 1998 12:03:53 -0500 "Najemy, Daniel"
<DNajemy@IMPS0014.US.DG.COM> writes:
>Greetings - hoping someone would be able to help here...
>
>I have a sub-routine that looks as follows:
>
>bsf     STATUS,RP0      ; switch to bank 0
>bcf     PORTC,6          ; light an led hanging off port c
>bcf     STATUS,RP0    ; switch back
>
>when I modify it as follows....
>bsf     STATUS,RP0      ; switch to bank 0
>bcf     PORTC,6          ; light an led hanging off port c
>bsf     PORTC,2         ;
>bcf     STATUS,RP0    ; switch back
>
>


        Looks like the classic read-modify-write without allowing enough
time for the port I/O lines to settle.  Recall that reading a port
actually reads the port pins, not the output register.  So...  if w is
available, you might do something like

        bank0           ; I have a macro for this...
        movfw   portc   ; Get current port settings in w
        andlw   b'10111111' ; Clear bit 6
        iorlw   b'00000100' ; Set bit 2
        movwf   portc   ; Update the port

Harold