51单片机I2C总线读回数据的问题,求解答
本帖最后由 woshi_ziyu 于 2013-11-27 08:56:59 编辑 就是用I2C总线发过去一个数据再读回来的程序,可是读回来的数据就是不对,不知道为什么。。。不管发什么,读回来的总是0xff。
#include<reg52.h>51 c I2C
#define uchar unsigned char
uchar a;
sbit sda=P2^0;
sbit scl=P2^1;
void delay()
{;;}
void delay1(int z)
{
intx,y;
for(x=0;x<z;x++)
for(y=0;y<110;y++);
}
void start()
{
sda=1;
delay();
scl=1;
delay();
sda=0;
delay();
}
void stop()
{
sda=0;
delay();
scl=1;
delay();
sda=1;
delay();
}
void respond()
{
uchar i;
scl=1;
delay();
while((sda==1)&&(i<250))
i++;
scl=0;
delay();
}
void init()
{
sda=1;
delay();
scl=1;
}
void write_byte(uchar dat)
{
uchar j;
uchar temp=dat;
for(j=0;j<8;j++)
{
temp=temp<<1;
scl=0;
delay();
sda=CY;
delay();
scl=1;
delay();
}
scl=0;
delay();
sda=1;
delay();
}
uchar read_byte()
{
uchar i,j,k;
scl=0;
delay();
sda=1;
delay();
for(i=0;i<8;i++)
{
scl=1;
delay();
if(sda==1)
j=1;
else
j=0;
k=((k<<1)|j);
scl=0;
delay();
}
return k;
}
void main()
{
init();
start();
write_byte(0xa0);
respond();
write_byte(3);
respond();
write_byte(0xfe);
respond();
stop();
delay1(100);
start();
write_byte(0xa0);
respond();
write_byte(3);
respond();
start();
write_byte(0xa1);
respond();
P1=read_byte();
stop();
}