通過芯片AT24C02控制P1口。程序：

#include<reg52.h>
sbit sda=P2^1;
sbit scl=P2^0;
void delay1()
{
 ;;;
}

void delay()
{
 int x,y;
 for(x=0;x<5;x++)
 for(y=0;y<120;y++);
}
void start()
{ sda=1;
 delay1();
 scl=1;
 delay1();
 sda=0;
 delay1();
}
void stop()
{
 sda=0;
 delay1();
 scl=1;
 delay1();
 sda=1;
 delay1();
}
void respons()
{
 sda=0;
 delay1();
 scl=1;
 delay1();
 scl=0;
 delay1();
}
void init()
{
 sda=1;
 scl=1;
}
void write_byte(unsigned char date)
{
 unsigned char temp,i;
 temp=date;
 scl=0;
 delay1();
 for(i=0;i<8;i++)
 {
 temp=temp<<1;
 sda=CY;
 delay1();
 scl=1;
 delay1();
 scl=0;
 delay1();
 } 
 sda=1;
 delay1();
}
unsigned char read_byte()
{
 unsigned char i,j,k;
 scl=0;
 delay1();
 sda=1;
 delay1();
 for(i=0;i<8;i++)
 {
  scl=1;
  delay1();
  j=sda;
  k=(k<<1)|j;
  scl=0;
  delay1();
 }
 return k;
}

void write_add(unsigned char addres,unsigned char date)
{
  start();
 write_byte(0xae);
 respons();
 write_byte(addres);
 respons();
 write_byte(date);
 respons();
 stop();
 
}
unsigned char read_add(unsigned char address)
{ unsigned char date;
  start(); 
 write_byte(0xae);
 respons();
 write_byte(address);
 respons();
 start();
 write_byte(0xaf);
 respons();
 date=read_byte();
 stop();
 return date;
}
void main()
{
 init();
 write_add(3,0x55);
 delay();
 P1=read_add(3);
 while(1);
}