I2C总线的相关程序

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sbit SCL = P2^0;sbit SDA = P2^1;sbit RS = P2^4;sbit RW = P2^5;sbit E = P2^6;void iic_start()//起始信号{  SDA = 1;  SCL = 1;  delay_us(1);  SDA = 0;  delay_us(1);  SCL = 0;//钳住总线}void iic_stop()  //终止信号{  SDA = 0;  SCL = 1;  delay_us(1);  SDA = 1;  delay_us(1);  SCL = 0;//钳住总线}

//下面是发送字节和接受字节的程序：

bit iic_send_byte(unsigned char byte){    unsigned char i;    for(i = 0; i < 8; i++)    {        SDA = byte & 0x80;//非0值，SDA=1，否则SDA=0SCL = 1;delay_us(1);SCL = 0;byte <<= 1;    }    SCL = 1;    SDA = 1;    delay_us(1);    if(0 == SDA)    {        ack = 1;    }    else    {        ack = 0;    }    SCL = 0;    return 0;}unsigned char iic_rcv_byte(){    unsigned char i;    unsigned char temp = 0;    unsigned char a;    SDA = 1;    for(i = 0; i < 8; i++)    {        SCL = 0;delay_us(1);SCL = 1;if(SDA){    a = 0x01;}else{    a = 0;}temp |= (a << (7 - i));delay_us(1);    }    SCL = 0;    return temp;}

下面是应答和非应答信号：

void iic_ack(){  SDA = 0;  SCL = 1;  delay_us(1);  SCL = 0;}void iic_noack(){  SDA = 1;  SCL = 1;  delay_us(1);  SCL = 1;}

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