I2C总线读写AT24c02的程序

#include <intrins.h>





#define OP_READ 0xa1            // 器件地址以及读取操作

#define        OP_WRITE 0xa0           // 器件地址以及写入操作





unsigned char code tab[]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90};





int eepromdata;                               //从EEPROM里读出来的数据





sbit SDA = P3^4;

sbit SCL = P3^3;





void delay()ms(unsigned char ms)        

{

       unsigned char i;

    while(ms--)

 {

           for(i = 0; i < 120; i++);

   }

}





void delay()(void)

{

       int k;

      for(k=0;k<400;k++);

}





void start()

{

       SDA = 1;

    SCL = 1;

    _nop_();

    _nop_();

    SDA = 0;

    _nop_();

    _nop_();

    _nop_();

    _nop_();

    SCL = 0;

}





void stop()

{

   SDA = 0;

    _nop_();

    _nop_();

    SCL = 1;

    _nop_();

    _nop_();

    _nop_();

    _nop_();

    SDA = 1;

}





unsigned char shin()



{

      unsigned char i,read_data;

  for(i = 0; i < 8; i++)

      {

           SCL = 1;

            read_data <<= 1;

            read_data |= (unsigned char)SDA;

            SCL = 0;

    }

   return(read_data);

}





bit shout(unsigned char write_data)

{

 unsigned char i;

    bit ack_bit;

        for(i = 0; i < 8; i++)          

    {

           SDA = (bit)(write_data & 0x80);

             _nop_();

            SCL = 1;

            _nop_();

            _nop_();

            SCL = 0;

            write_data <<= 1;

   }

   SDA = 1;                        

    _nop_();

    _nop_();

    SCL = 1;

    _nop_();

    _nop_();

    _nop_();

    _nop_();

    ack_bit = SDA;                  // 读取应答

     SCL = 0;

    return ack_bit;                 // 返回AT24Cxx应答位

}





void write_byte(unsigned char addr, unsigned char write_data)

{

  start();

    shout(OP_WRITE);

    shout(addr);

        shout(write_data);

  stop();

     delay()ms(10);              

}





unsigned char read_current()

{

  unsigned char read_data;

    start();

    shout(OP_READ);

     read_data = shin();

 stop();

     return read_data;

}





unsigned char read_random(unsigned char random_addr)

{

 start();

    shout(OP_WRITE);

    shout(random_addr);

 return(read_current());

}





void display(int k)

{

    P2=0xfe;                                //最高位数码管1234

        P0=tab[k/1000];

     delay();

    P2=0xfd;

    P0=tab[k00/100];

    delay();

    P2=0xfb;

    P0=tab[k0/10];

      delay();

    P2=0xf7;

    P0=tab[k];

  delay();

    P2=0xff;

}





void main(void)

{

       SDA = 1;

    SCL = 1;

    eepromdata=0;

       write_byte(0x01, 0x55);                 //向0x01地址写入0x55(85)的数据

      delayms(250);

       write_byte(0x02, 0xAA);                 //向0x02地址写入0xAA(170)的数据

     delayms(250);

       delayms(250);

       eepromdata= read_random(0x02);  // 读取其中一个地址内的数据来验证

  delayms(250);

       while(1)

    {

   display(eepromdata);

        }

}