i2c.h

电动车测试平台控制系统。自动测量电动车各项参数

#ifndef _I2C_H_
#define _I2C_H_

sbit I2C_SCL = P1^0;
sbit I2C_SDA = P1^1;
bit ack;

void I2CStart ()
{
    I2C_SDA = HIGH; //起始信号
    _nop_ ();
    I2C_SCL = HIGH;
    _nop_ ();   //建立时间大于4.7us
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
    I2C_SDA = LOW;
    _nop_ ();   //锁定时间大于4us
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
    I2C_SCL = LOW;  //钳住总线
    _nop_ ();
    _nop_ ();
}

void I2CStop ()
{
    I2C_SDA = LOW;  //发送结束条件数据信号
    _nop_ ();
    I2C_SCL = HIGH;
    _nop_ ();   //建立时间大于4us
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
    I2C_SDA = HIGH;
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
}

void I2CAck (bit a)	
{
    if (a == FALSE)
        I2C_SDA = LOW;
    else
        I2C_SDA = HIGH;
    _nop_ ();
    _nop_ ();
    _nop_ ();
    I2C_SCL = HIGH;
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
    _nop_ ();
    I2C_SCL = LOW;
    _nop_ ();
    _nop_ ();
}

void SendByte (unsigned char c)
{
    unsigned char data i;
    for (i = 0;  i < 8;  i ++)
    {
        if ((c << i) & 0x80)
            I2C_SDA = HIGH;
        else
            I2C_SDA = LOW;
        _nop_ ();
        I2C_SCL = HIGH;
        _nop_ ();
        _nop_ ();
        _nop_ ();
        _nop_ ();
        _nop_ ();
        I2C_SCL = LOW;
    }
    _nop_ ();
    _nop_ ();
    I2C_SDA = HIGH;
    _nop_ ();
    _nop_ ();
    I2C_SCL = HIGH;
    _nop_ ();
    _nop_ ();
    _nop_ ();
    if (I2C_SDA == HIGH)
        ack = FALSE;
    else
        ack = TRUE;
    I2C_SCL = LOW;
    _nop_ ();
    _nop_ ();
}

unsigned char RcvByte ()
{
    unsigned char data ret,i;
    ret = 0;
    I2C_SDA = HIGH;
    for (i = 0; i < 8; i ++)
    {
        _nop_ ();
        I2C_SCL = LOW;
        _nop_ ();
        _nop_ ();
        _nop_ ();
        _nop_ ();
        _nop_ ();
        I2C_SCL = HIGH;
        _nop_ ();
        _nop_ ();
        ret <<= 1;
        if (I2C_SDA == HIGH)
            ret ++;
        _nop_ ();
        _nop_ ();
    }
    I2C_SCL = LOW;
    _nop_ ();
    _nop_ ();
    return ret;
}

bit I2CSend (unsigned char sla, unsigned char suba, unsigned char c)
{
    I2CStart ();
    SendByte (sla);
    if (ack == FALSE)
        return FALSE;

	SendByte (suba);     
    if (ack == FALSE)
        return FALSE;

    SendByte (c);
    if (ack == FALSE)
        return FALSE;
    I2CStop ();
    return TRUE;
}

/*
bit I2CReceive (unsigned char sla, unsigned char *c)
{
    I2CStart ();
    SendByte (sla + 1);
    if (ack == FALSE)
        return FALSE;
    *c = RcvByte ();
    I2CAck (TRUE);
    I2CStop ();
    return TRUE;
}
*/

bit I2CSendBuf (unsigned char sla,unsigned char suba,unsigned char *buf,unsigned char num) reentrant
{
    unsigned char data i;

    I2CStart ();               //启动总线
    SendByte (sla);            //发送器件地址
    if (ack == FALSE)
        return FALSE;
    SendByte (suba);           //发送器件子地址
    if (ack == FALSE)
        return FALSE;

    for (i = 0; i<num; i ++)
    {
        SendByte (*buf);       //发送数据
        if (ack == FALSE)
            return FALSE;
        buf ++;
    }

    I2CStop();                 //结束总线
    return TRUE;
}

bit I2CRcvBuf (unsigned char sla,unsigned char suba,unsigned char *buf,unsigned char num) reentrant
{
    unsigned char data i;

    I2CStart ();               //启动总线
    SendByte(sla);             //发送器件地址
    if (ack == FALSE)
        return FALSE;
    SendByte(suba);            //发送器件子地址
    if (ack == FALSE)
        return FALSE;

    I2CStart ();
    SendByte (sla + 1);
    if (ack == FALSE)
        return FALSE;

    for (i = 0;  i < num - 1; i++)
    {
        *buf = RcvByte ();         //发送数据
        I2CAck (FALSE);            //发送就答位
        buf ++;
    }
    *buf = RcvByte ();
    I2CAck (TRUE);                 //发送非应位
    I2CStop ();                    //结束总线
    return TRUE;
}

#endif