i2c.c

此程序是用IO模拟I2C接口的驱动

void I2cWait(void)    //file://延/时，I2c大约30k/s
{
  unsigned char i;

  for(i=0;i<10;i++)
  {
    i=i;//_nop_();
  }
}

void I2cStart(void)   // file://起/始信号
{
  SDA = 1;
  SCL = 1;
  I2cWait();
  SDA = 0;
  I2cWait();
  SCL = 0;
}

void I2cStop(void)    //file://停/止信号
{
  SDA = 0;
  I2cWait();
  SCL = 1;
  I2cWait();
  SDA = 1;
  I2cWait();
}

void SendAck(bit ack)  //  file://送/确认信号到slave
{
  SDA = ack;
  SCL = 1;
  I2cWait();
  SCL = 0;
}

bit I2cSendByte(unsigned char bytedata)  //file://送/一字节数据到slave
{
  unsigned char i;
  bit ack;

  for(i=0;i<8;i++)
  {
    if(bytedata & 0x80)
      SDA = 1;
    else
      SDA = 0;

    bytedata <<= 1;
    I2cWait();

    SCL = 1;
    I2cWait();
    SCL = 0;
    I2cWait();
  }

  SDA = 1;
  I2cWait();
  SCL = 1;
  I2cWait();

  ack = SDA;     // file://接/收确认信号:1,没收到应答；0，收到应答

  SCL = 0;
  I2cWait();

  return ack;
}

unsigned char I2cReceiveByte(void)  //file://接/收1字节数据
{
  unsigned char i;
  unsigned char bytedata = 0;

  for(i=0;i<8;i++)
  {
    SCL = 1;
    I2cWait();

    bytedata <<= 1;

    if(SDA)
    {
      bytedata |= 0x01;
    }
    SCL = 0;
    I2cWait();
  }

  return bytedata;
}

unsigned char I2cByteRead(unsigned char device,unsigned char address)
{      //file://从/slave接收1字节数据
  unsigned char bytedata;

  I2cStart();
  I2cSendByte(device);
  I2cSendByte(0);
  I2cSendByte(address);
  I2cStart();
  I2cSendByte(device|0x01);
  bytedata = I2cReceiveByte();
  SendAck(1);
  I2cStop();

  return bytedata;
}


void I2cByteWrite(unsigned char device,unsigned int address,unsigned char bytedata)
{      //file://将/数据写入指定slave的地址内
   unsigned char i;
   unsigned char addressh,addressl;
   bit ack;

   addressl = address&0xFF;
   addressh = address>>8;
   for(i=0;i<10;i++)
   {
     I2cStart();
     ack = I2cSendByte(device);
     if(ack==1)
     {
       I2cStop();
       continue;
     }
     ack = I2cSendByte(addressh);
     if(ack==1)
     {
       I2cStop();
       continue;
     }
     ack = I2cSendByte(addressl);
     if(ack==1)
     {
       I2cStop();
       continue;
     }
     ack = I2cSendByte(bytedata);
     if(ack==1)
     {
       I2cStop();
       continue;
     }
     I2cStop();
     if(ack==0)  break;    //file://正/常，跳出循环
   }
//   DelayX5ms(2);
}