Cliff Davis

Making PORT A an input

Discussion created by Cliff Davis on Oct 29, 2009
Latest reply on Oct 30, 2009 by CompilerGuru

Is it possible to make Port A an input for the push button componet. If so how would I go about doing this?  Port A is set up as the input and the value never changes in the address. This is the code i am working with.

 

 

XDEF          Entry

ABSENTRY   Entry

ROMStart     EQU $4000

        PORTA EQU 0

        PORTB EQU 1

        DDRA   EQU 2

        DDRB    EQU 3

        ORG ROMStart

Entry:

         LDAA    #$00

         STAA    DDRA

         LDAB     #$FF

         STAB     DDRB

         MOVB     #0,PORTB

Loop:

 

         BRCLR    PORTA,#$FF,Loop

         LDAA     PORTA

         STAA     PORTB

         BRA       Loop

         RTS

;*****************************************

;* Interrupt Vectors *

;*****************************************

        ORG $FFFE

       DC.W Entry

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