51单片机IIC程序.doc

#include<AT89X51.H>
sbit sda=P2^0;
sbit scl=P2^1;
void delay()
{;;}
void start() //起始信号
{
sda=1;
delay();
scl=1;
delay();
sda=0;
delay();
}
void stop() //终止信号
{
sda=0;
delay();
scl=1;
delay();
sda=1;
delay();
}
void respons() //应答信号
{
char i;
scl=1;
delay();
while((sda==1)&&(i<250))i++;
scl=0;
delay();
}
void init() //初始化
{
sda=1;
scl=1;
}
void write_byte(char date) //写字节
{
char i,temp;
temp=date;

scl=0;
delay();
for(i=0;i<8;i++)
{
temp=temp<<1;
sda=CY;
delay();
scl=1;
delay();
scl=0;
delay();
}
sda=1;
delay();
}
char read_byte() //读字节
{
char i,j,k;
scl=0;
delay();
sda=1;
delay();
for(i=0;i<8;i++)
{
scl=1;
delay();
j=sda;
k=(k<<1)|j;
scl=0;
delay();
}
return k;
}

void delay1(int z) //延时函数;
{
int x,y;
for(x=z;x>0;x--)
for(y=110;y>0;y--);
}
void main() //主程序
{
init();
start();
write_byte(0xa0);
respons();
write_byte(3);
respons();
write_byte(0xfe);
respons();
stop();

delay1(100);
start();
write_byte(0xa0);
respons();
write_byte(3);
respons();
start();
write_byte(0xa1);
respons();
P1=read_byte();
stop();
while(1);
}