On Mon, 27 Jan 2003, =C5ke Neehr wrote:

*>Hello!
*>
*>I=B4m using portb 0-6 on a Pic 16F84 to drive
*>a LED-display and I want to use portb 7
*>to control a transistor with but my displayloop
*>set the port to zero every time!
*>
*>Is there any good trick to sole this out?

Make a variable to hold the state of the RB7 (transistor off or on), call
it Foutput_mirror. Then use it in the LED display code like this:

Instead of

        movwf   PORTB                   ; output display

use

        andlw   RB7MASK                 ; clear the 7th bit
        iorwf   Foutput_mirror,w        ; mask in the transistor control
        movwf   PORTB                   ; output display and transistor

; define this mask (before you use it)
RB7MASK EQU     b'01111111'             ; mask the highest bit

Then elsewhere in your program:

turn on transistor:

        bsf     Foutput_mirror,7

turn off:

        bcf     Foutput_mirror,7

then call the display routine and it will be output. You can also output
it directly.

bye,

        Peter

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