微机新手求教关于I2C总线以及2402的问题，程序调试！

只看该作者 · 2011-9-9 15:53

我是一个微机新手。用8255的两个管脚分别接2402的SDA 和 SCL 模拟I2C总线向2402输入一页数据再读出来，用8253给出精确定时。但是在调试程序的时候出现了一个情况，就是写入8位数据之后接收不到应答。另外，我用8255的两个管脚分别接两个LED灯上面，分别表示是否接受到应答，调试程序的时候发现系统接收不到应答之后8255也没有控制相应的LED灯亮！！！8255没有问题的。
请问各位高手知道这是怎么回事吗？这搞得我都不知道怎么调试，拳打**的感觉！！！
以下是我的程序，烦请路过的高手看下，不胜感激！！！
其中 8255的PB0接SDA PC0接SCL PA0~3接LED 是用来显示读出来的数据的。PA7接8253的OUT  PC7和PC6分别接两个LED用来显示是否接到应答

ioport
equ 0d400h-0280h
io8255
equ ioport+28bh
;8255控制寄存器地址
io8255a
equ ioport+288h
;A口地址
io8255b
equ ioport+289h
;B口地址
io8255c
equ ioport+28ah
;C口地址
io8253             equ ioport+283h    ;8253控制寄存器地址
io82530             equ ioport+280h ;通道0地址
data segment
list db 01h,02h,03h,04h,05h,06h,07h,08h;
count db ?
data ends
stacks segment stack
db 100 dup(?)
stacks ends

code segment

  assume cs:code,ds:data,ss:stacks
start:
  mov ax,stacks
  mov ss,ax
  mov ax,data
  mov ds,ax

  mov dx,io8255
  mov al,90h
  out dx,al
  call init
  call delay1
sendadrwrite:
      mov bl,0A0h
;发送器件地址

  mov al,bl
;bl中存放现有要发送的数据（器件地址和片内写地址),原数据始终在BH中

  call senddata
      call testack;检测应答信号

  call delay

  mov
bl,00h
;发送存储地址

  mov al,bl

  call senddata
      call testack;检测应答信号

  call delay
mov bx,00h
A:  mov al,list[bx]
mov dx,io8255a
in al,dx
mov bl,al
inc bx
call senddata
call testack
cmp bx,7
jc A

  call stop
      call delay10
      mov dx,io8255
      mov al,90h
      out dx,al
      call init
      call delay1
      mov bh,08h
sendadread: mov bl,0A0h
;发送器件地址

  mov al,bl

  call senddata

  call testack
;检测应答信号

  call delay

  mov
bl,00h
;发送存储单元地址

  mov al,bl

  call senddata

  call testack
;检测应答信号

  call delay

  mov bl,0A1h

  mov al,bl

  call senddata

  call testack
;检测应答信号

  call delay

  mov cl,07h

  mov ch,08h
readdata: mov bl,00h

  mov dx,io8255          ;设8255为A、C口输出，B口输入，B口接SDA

  mov al,82h

  out dx,al

  mov al,00h

  mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL置0

  call delay

  mov al,01h

  mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL置1

  call delay

  mov dx,io8255b

  in al,dx
;读入PB0上的数据存入到BL中

  shl al,07h
;左移CL位

  or bl,al

  call delay

  mov al,00h

  mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL置0

  dec ch

  jnz readdata

  dec cl
      call testack
disLED:
      mov dx,io8255             ;A输出 BC输入
      mov al,8Bh
      out dx,al
      mov al,bl
;显示LED指示灯

  mov dx,io8255a

  out dx,al

      dec bh
      jnz sendadread
stopread:

      mov dx,io8255          ;设8255为A、B、C输出

  mov al,80h

  out dx,al


  mov al,00h
;直接给停止信号

  mov dx,io8255b

  out dx,al

  mov al,01h

  mov dx,io8255c

  out dx,al

  call delay

  mov al,01h

  mov dx,io8255b

  out dx,al

  call delay
exit:
  mov ah,4ch
      int 21h

senddata proc
near
         push cx
         mov dx,io8255          ;设8255为A输入 B、C输出

  mov al,90h

  out dx,al

         mov cl,08h
senddata1: mov dx,io8255c

  mov al,00h

  out dx,al
;置SCL为0

  call delay

  mov al,bl
;bl中存放当前传输的数

  mov dx,io8255b

  out dx,al
;将AL中最低位数据通过PB0输出给SDA

  call delay

  mov al,01h

  mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL置1，此时SDA数据有效

  call delay

  mov al,00h

  out dx,al
;PC0接SCL，将SCL置0,此时可更改SDA

  call delay
next:
  shr bl,1
;将BL中的数据右移一位，高位添0

  dec cl
;已经传送了一位

  jnz senddata1
;若未发送完则继续发送

  call delay





  pop cx
      ret
senddata endp


init proc near

  mov al,01h

  mov dx,io8255b

  out dx,al          ;PB0接SDA，将SDA置1

  call delay
      mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL置1

  call delay

  mov al,00h

  mov dx,io8255b

  out dx,al
;PB0接SDA，将SDA清0，开始信号

  call delay


  mov dx,io8255c

  out dx,al
;PC0接SCL，将SCL清0
      ret
init endp

stop proc near

  mov al,00h

  mov dx,io8255b

  out dx,al
      call delay

  mov al,01h

  mov dx,io8255c

  out dx,al

  call delay

  mov al,01h

  mov dx,io8255b

  out dx,al

  call delay

  ret
stop endp

只看该作者 · 2011-9-9 15:54

delay    proc near                ;延迟子程序
   push cx
      push dx

delay5us: mov dx,io8253
      mov al,10h
      mov dx,io82530
      mov al,05h
      in al,dx
testout5us:  mov dx,io8255a                ;8255a口输入 OUT端输入PA7
      in al,dx
      rcl al,1                      ;al 循环左移一位，以检测CF是否为1
      jnc testout5us
      pop dx
      pop cx
      ret
delay    endp

delay1  proc near          ;1ms延时子程序
      push cx
      push dx

delay1ms: mov dx,io8253
      mov al,30h          ;选择先低后高写入
      mov dx,io82530
      mov ax,3E8h             ;一毫秒要计数1000，0000 0011 1110 1000
      in ax,dx

testout1ms:  mov dx,io8255a                ;8255a口输入 OUT端输入PA7
      in al,dx
      rcl al,1                      ;al 循环左移一位，以检测CF是否为1
      jnc testout1ms
      pop dx
      pop cx
      ret
delay1 endp

delay10  proc near          ;10ms延时子程序
      push cx
      push dx

delay10ms: mov dx,io8253
      mov al,30h          ;选择先低后高写入
      mov dx,io82530
      mov ax,2710h             ;10毫秒要计数10000
      in ax,dx

testout10ms:  mov dx,io8255a                ;8255a口输入 OUT端输入PA7
      in al,dx
      rcl al,1                      ;al 循环左移一位，以检测CF是否为1
      jnc testout10ms
      pop dx
      pop cx
      ret
delay10 endp

testack  proc near
   push cx
      mov cx,0ffh
      mov al,00h
   mov dx,io8255c
   out dx,al ;PC0接SCL，将SCL置0
      nop
   mov al,01h
   mov dx,io8255b
   out dx,al ;PB0接SDA，将SDA置1
   nop
   mov al,01h
   mov dx,io8255c
   out dx,al ;PC0接SCL，将SCL置1
   call delay
read:    mov al,92h ;读入SDA状态,若是零则表明写成功
   mov dx,io8255
   out dx,al
   mov dx,io8255b
   in  al,dx
   mov bl,al
   mov dx,io8255c
   mov al,00h
   out dx,al
   mov al,bl
   and al,01h
   jz  change
   dec cx
   jcxz error
   jmp  read
error: mov dx,io8255c ;此时用LED8显示未接收到响应信号
   mov al,80h
   out dx,al
   jmp exit ;结束
change:  mov dx,io8255          ;设8255为A口输入，B、C输出
   mov al,90h
   out dx,al
   mov dx,io8255c
   mov al,40h
   out dx,al ;此时用LED7表明接收到响应信号
   pop cx
      ret
testack  endp
code ends
end start