4a_8255输出.asm

来自「单片机杭州天煌教仪自带例程单片机杭州天煌教仪自带例程」· 汇编 代码 · 共 30 行

   ;8255
       org 0000h
       LJMP START
       ORG 0030h

START:     
       mov   a,#80h
       mov   dptr,  #7FFFH
       movx  @dptr,a
Loop:
       mov   a, #0FEh
       mov   r2, #8   
Output:
       mov   dptr,#7CFFH
       movx  @dptr, a
       Acall  Delay
       rl    a
       djnz  r2, Output
       ljmp  Loop

Delay:
       mov   r6, #0
       mov   r7, #0
DelayLoop:
       djnz  r6, DelayLoop
       djnz  r7, DelayLoop
       ret

       end