8255a.asm

单片机并口扩展芯片8255A源码

ORG 0000H
LJMP INIT
INIT:
MOV DPTR,#0003H 
MOV A,#0A6H
MOVX @DPTR,A
START:
MOV DPTR,#0000H 
MOV A,#0FEH
MOVX @DPTR,A
MOV R0,#2
ACALL DELAY
MOVX @DPTR,A
MOV R0,#20
ACALL DELAY
LJMP START
DELAY:
MOV R2,#200
DEL2:MOV R1,#200
DEL1:DJNZ R1,DEL1
DJNZ R2,DEL2
DJNZ R0,DELAY
RET