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-0280h io8255a equ ioport+288h

io8255b equ ioport+289h

io8255c equ ioport+28ah

io8255d equ ioport+28bh

portc1 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 0ffh

data ends

code segment

assume cs:code, ds:data

start:mov ax,data

mov ds,ax

mov dx,io8255d

mov al,90h

out dx,al

lea di,portc1

re_on:mov al,[di]

inc di

cmp al,0ffh

jz exit

mov dx,io8255c

on: out dx,al

call delay

jmp re_on

exit:mov ah,4ch

int 21h

delay proc near

mov cx,0ffffh

de1:mov bx,0ff0h

de0:dec bx

jnz de0

loop de1

ret

delay endp

code ends

end start

data segment

ioport equ 0ff00h-0280h

io8255a equ ioport+288h

io8255b equ ioport+289h

io8255c equ ioport+28ah

io8255d equ ioport+28bh

portc1 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 0ffh

data ends

code segment

assume cs:code, ds:data

start:mov ax,data

mov ds,ax

mov dx,io8255d

mov al,90h

out dx,al

lea di,portc1

re_on:mov al,[di]

inc di

cmp al,0ffh

jz exit

mov dx,io8255c

on: out dx,al

call delay

jmp re_on

exit:mov ah,4ch

int 21h

delay proc near

mov cx,0ffffh

de1:mov bx,0ff0h

de0:dec bx

jnz de0

loop de1

ret

delay endp

code ends

end start

说明：db循环写三次可实现交通灯的机制。