51读写串行EEPROM芯片at2402程序（C）

    sbit SCL=P1^7;/*假设由P1.7和P1.6控制*/
    sbit SDA=P1^6;

/********** Function Definition　函数定义 ************/

    void DELAY(unsigned int t) /*延时函数*/
    {
        while(t!=0)
            t--;
    }

    void I2C_Start(void)
    {
        /*启动I2C总线的函数，当SCL为高电平时使SDA产生一个负跳变*/
        SDA=1;
        SCL=1;
        DELAY(DELAY_TIME);
        SDA=0;
        DELAY(DELAY_TIME);
        SCL=0;
        DELAY(DELAY_TIME);
    }

    void I2C_Stop(void)
    {
        /*终止I2C总线，当SCL为高电平时使SDA产生一个正跳变*/
        SDA=0;
        SCL=1;
        DELAY(DELAY_TIME);
        SDA=1;
        DELAY(DELAY_TIME);
        SCL=0;
        DELAY(DELAY_TIME);
    }

    void SEND_0(void)   /* SEND ACK */
    {
        /*发送0，在SCL为高电平时使SDA信号为低*/
        SDA=0;
        SCL=1;
        DELAY(DELAY_TIME);
        SCL=0;
        DELAY(DELAY_TIME);
    }

    void SEND_1(void)
    {
        /*发送1，在SCL为高电平时使SDA信号为高*/
        SDA=1;
        SCL=1;
        DELAY(DELAY_TIME);
        SCL=0;
        DELAY(DELAY_TIME);
    }

    bit Check_AcknowLEDge(void)
    {
        /*发送完一个字节后检验设备的应答信号*/
        SDA=1;
        SCL=1;
        DELAY(DELAY_TIME/2);
        F0=SDA;
        DELAY(DELAY_TIME/2);
        SCL=0;
        DELAY(DELAY_TIME);
        if(F0==1)
            return FALSE;
        return TRUE;
    }

    void WriteI2CByte(char b)reentrant
    {
        /*向I2C总线写一个字节*/
        char i;
        for(i=0;i<8;i++)
            if((b<                SEND_1();
            else
                SEND_0();
    }

    char ReadI2CByte(void)reentrant
    {
        /*从I2C总线读一个字节*/
        char b=0,i;
        for(i=0;i<8;i++)
        {
            SDA=1;    /*释放总线*/
            SCL=1;    /*接受数据*/
            DELAY(10);
            F0=SDA;
            DELAY(10);
            SCL=0;
            if(F0==1)
                {
                    b=b<<1;
                    b=b|0x01;
                 }
            else
                b=b<<1;
        }
        return b;
    }

/**********以下为读写24c02的函数**********/
void Write_One_Byte(char addr,char thEDAta)
{
          bit acktemp=1;
          /*write a byte to mem*/
          I2C_Start();
          WriteI2CByte(0xa0);
          acktemp=Check_Acknowledge();
          WriteI2CByte(addr);/*address*/
          acktemp=Check_Acknowledge();
          WriteI2CByte(thedata);/*thedata*/
          acktemp=Check_Acknowledge();
          I2C_Stop();

}

void Write_A_Page(char *buffer,char addr)
{
          bit acktemp=1;
          bit wrtmp;
          int i;
          /*write a page to at24c02*/
          I2C_Start();
          WriteI2CByte(0xa0);
          acktemp=Check_Acknowledge();
          WriteI2CByte(addr);/*address*/

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