這是電路圖，這是從這個項目中取得的文件里面有電路圖和仿真文件：http://www.raoushi.com/bbs/dpj-22586-1.html
下面是 i2c.c文件：
#include <reg52.h>
#include "i2c.h"
#include "delay_ms.h"
void delay()
{
;;
}
void i2cinit()//總線初始化
{
SDA = 1;
delay();
SCL = 1;
delay();
}
void start()//啟動信號
{
SDA = 1;
SCL = 1;
delay();
SDA = 0;
delay();
}
void stop()//停止信號
{
SDA = 0;
delay();
SCL = 1;
delay();
SDA = 1;
delay();
}
void respons()//應答信號
{
unsigned char i = 0;
SCL = 1;
delay();
while(SDA == 1 && i < 255)//等待應答，過一段時間不應答退出循環
i++;
SCL = 0;
delay();
}
void writebyte(unsigned char date)//寫一個字節
{
unsigned char i,temp;
temp = date;
for(i = 0; i < 8; i++)
{
temp <<= 1;//temp左移一位后高位進CY
SCL = 0;
delay();
SDA = CY;
delay();
SCL = 1;
delay();
}
SCL = 0;//應答信號中SCL = 1，所以這里要置0
delay();
SDA = 1;//用完要釋放數據總線
delay();
}
unsigned char readbyte()//讀一個字節
{
unsigned char i,k;
SCL = 0;
delay();
SDA = 1;
for(i = 0; i < 8; i++)
{
SCL = 1;
delay();
k = (k << 1) | SDA; //和最低位或，一位位送到K
SCL = 0;
delay();
}
delay();
return k;
}
void write_add(unsigned char address,unsigned char date)//向地址寫一個字節數據
{
start();
writebyte(0xa0);//A0,A1,A2接地，AT24C02芯片地址為1010，送控制字為1010A2A1A0R/~W
respons();
writebyte(address);
respons();
writebyte(date);
respons();
stop();
}
unsigned char read_add(unsigned char address)//向地址讀一個字節數據
{
unsigned char date;
start();
writebyte(0xa0);//A0,A1,A2接地，AT24C02芯片地址為1010，送控制字為1010A2A1A0R/~W
respons();
writebyte(address);
respons();
start();
writebyte(0xa1);//A0,A1,A2接地，AT24C02芯片地址為1010，送控制字為1010A2A1A0R/~W
respons();
date = readbyte();
stop();
return date;
}
//向地址寫n個字節數據,數據存放在指針P指的數組中
void write_n_add(unsigned char * p,unsigned char address,unsigned char n)
{
unsigned char i;
for(i = 0; i < n; i++)
{
write_add((address + i),*(p + i));
delay_ms(20);//一定要適當延時，不然寫不進去
}
}
//向地址讀n個字節數據,數據存放在指針P指的數組中
void read_n_add(unsigned char * p,unsigned char address,unsigned char n)
{
unsigned char i;
for(i = 0; i < n; i++)
{
*(p + i) = read_add(address + i);
}
}