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+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。