On Wednesday 11 Jun 2003 12:06, you wrote:
> It's easier to read and more informative to use includes and an
> itemised CONFIG statement
>
<cut>

Now that I understand how to write to a port I thought that reading from a
port would be just as easy, but it seems it's not.

This code is based on that provided by Jinx but I seem to be missing
something. The LED is always on no matter what the state of pin 18.

Could someone put me on the right track?

        PROCESSOR p16f628
        INCLUDE p16f628.inc
        __CONFIG _CP_OFF &_WDT_OFF &_BODEN_OFF &_PWRTE_ON &_INTRC_OSC_NOCLKOUT
        ERRORLEVEL -302                         ; Don't care about the "bank bits" messages

;****Set up the port****

                bsf             STATUS,5                ;Switch to Bank 1
                movlw   b'00000010'     ;Port A1 input the rest outputs
                movwf   TRISA           ;to output.

                movlw   07h                     ;set Port A1
                movwf           CMCON           ;to digital mode

                bcf             STATUS,5                ;Switch back to Bank 0

                clrf            PORTA

;****Turn the LED on if pin 18 is grounded****

Start           btfsc   PORTA, 1                ;wait for a.1 to ground
                goto            Start

                movlw   04h                     ;Turn on the LED
                movwf   PORTA

                goto            Start

                end

--
Regards,
Phil.

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