Nick Veys wrote:

> loopage
>   bsf PORTA,2
>   bsf PORTA,3
>   bsf PORTA,4
>   bsf PORTA,5
>   DELAY_MILLI 250
>   bcf PORTA,2
>   bcf PORTA,3
>   bcf PORTA,4
>   bcf PORTA,5
>   DELAY_MILLI 250
>   goto loopage
>
>  end

The BSF instruction first reads PORTA, sets bit_X and then writes the
data back to PORTA.

If RA2,3,4 are read by the processor as being logic 0, then logic 0 is
written back to the PORTA. Thus RA2,3,4 for the most part stay = 0, and
only RA5 is ON.

If you connect all the LEDs to the VCC rail instead of GND, you may find
that they all stay on except RA5.

Please note that RA4 is open collector and will only work the LED if it
connected to VCC.

Try...

Loop    movlw b'00111100'               ; LEDs = OFF
        movwf PORTA
        DELAY_MILLI 250

        clrf PORTA                      ; LEDs = ON
        DELAY_MILLI 250
        goto Loop

This assumes all LEDs are connected to VCC via resistor to PORTA.

--
Best regards

Tony

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

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