6-7 8255 控制交通灯

一、实验目的

并行接口8255实现十字路口交通灯模拟。

二、实验内容

l7、l6、l5 作为南北交通灯与pc7、pc、pc5 相连，

l2、l1、l0作为东西交通灯与pc2、pc1、pc0相连。

使6个灯有规律的亮灭。

四、汇编程序data
segment

ioport equ 0ff00h-0280hio8255a equ ioport+288hio8255b equ ioport+289hio8255c equ ioport+28ahio8255d equ ioport+28bhportc1 db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h
db 0ffhdata endscode segmentassume cs:code, ds:datastart:mov ax,data mov ds,ax mov dx,io8255d mov al,90h out dx,al lea di,portc1re_on:mov al,[di] inc di cmp al,0ffh jz exit mov dx,io8255con: out dx,al call delay jmp re_onexit:mov ah,4ch int 21h delay proc near mov cx,0ffffhde1:mov bx,0ff0hde0:dec bx jnz de0 loop de1 ret delay endpcode endsend start

data segmentioport equ 0ff00h-0280hio8255a equ ioport+288hio8255b equ ioport+289hio8255c equ ioport+28ahio8255d equ ioport+28bhportc1 db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h db 24h,44h,04h,44h,04h,44h,04h db 81h,82h,80h,82h,80h,82h,80h
db 0ffhdata endscode segmentassume cs:code, ds:datastart:mov ax,data mov ds,ax mov dx,io8255d mov al,90h out dx,al lea di,portc1re_on:mov al,[di] inc di cmp al,0ffh jz exit mov dx,io8255con: out dx,al call delay jmp re_onexit:mov ah,4ch int 21h delay proc near mov cx,0ffffhde1:mov bx,0ff0hde0:dec bx jnz de0 loop de1 ret delay endpcode endsend start
说明：db循环写三次可实现交通灯的机制。