STM32硬件IIC

/**
  * @brief   写一个字节到I2C设备中
  * @param   
  *        @arg pBuffer:缓冲区指针
  *        @arg WriteAddr:写地址 
  * @retval  正常返回1，异常返回0
  */
uint8_t I2C_ByteWrite(u8 pBuffer, u8 WriteAddr)
{
  /* Send STRAT condition */
  I2C_GenerateSTART(macI2Cx, ENABLE);
    
    I2CTimeout = I2CT_FLAG_TIMEOUT;


 /* Test on EV5 and clear it */
//启动信号发出之后要等待状态寄存器SR1的位0（SB=1）,状态寄存器SR2的位1(BUSY=1)和位0(MSL=1),此时表明主模式下，起始条件已发送，总线处于忙状态；确保IIC通讯正确
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_MODE_SELECT))
  {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
  } 

  /* Send slave address for write */
  I2C_Send7bitAddress(macI2Cx, MPU6050_SLAVE_ADDRESS, I2C_Direction_Transmitter);//7bit slave address + read/write (0write,1 read)
  
    I2CTimeout = I2CT_FLAG_TIMEOUT;
    
  /* Test on EV6 and clear it */
    //从机地址发出之后，等待 BUSY, MSL, ADDR, TXE and TRA flags标志位
     while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) 
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
  }  
      
  /* Send the slave's internal address to write to */
  I2C_SendData(macI2Cx, WriteAddr);
  
    I2CTimeout = I2CT_FLAG_TIMEOUT;
  /* Test on EV8 and clear it */
    /* TRA, BUSY, MSL, TXE and BTF flags */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
  } 

  /* Send the byte to be written */
  I2C_SendData(macI2Cx, pBuffer); 
    
    I2CTimeout = I2CT_FLAG_TIMEOUT;
   
  /* Test on EV8 and clear it */
    /* TRA, BUSY, MSL, TXE and BTF flags */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))    
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
  } 
    
  /* Send STOP condition */
  I2C_GenerateSTOP(macI2Cx, ENABLE);
    
    return 1; //正常返回1
}

IIC事件检测：498页。STM32的硬件IIC通信非常严格，每一步都要检测相应的标志位是否正确，确保通信不会出错。

/**
  * @brief   从I2C设备里面读取一块数据 
  * @param   
  *        @arg pBuffer:存放从slave读取的数据的缓冲区指针
  *        @arg WriteAddr:接收数据的从设备的地址
  *     @arg NumByteToWrite:要从从设备读取的字节数
  * @retval  正常返回1，异常返回0
  */
uint8_t I2C_BufferRead(u8* pBuffer, u8 ReadAddr, u16 NumByteToRead)
{  
  I2CTimeout = I2CT_LONG_TIMEOUT;
    
  while(I2C_GetFlagStatus(macI2Cx, I2C_FLAG_BUSY)) // Added by Najoua 27/08/2008    
  {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
    
  I2C_GenerateSTART(macI2Cx, ENABLE);
  
    I2CTimeout = I2CT_FLAG_TIMEOUT;
     
  /* Test on EV5 and clear it */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_MODE_SELECT))
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
    
  /* Send slave address for write */
  I2C_Send7bitAddress(macI2Cx, MPU6050_SLAVE_ADDRESS, I2C_Direction_Transmitter);

    I2CTimeout = I2CT_FLAG_TIMEOUT;
     
  /* Test on EV6 and clear it */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED)) 
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
    
  /* Clear EV6 by setting again the PE bit */
  I2C_Cmd(macI2Cx, ENABLE);

  /* Send the slave's internal address to write to */
  I2C_SendData(macI2Cx, ReadAddr);  

    I2CTimeout = I2CT_FLAG_TIMEOUT;
     
  /* Test on EV8 and clear it */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED))
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
    
  /* Send STRAT condition a second time */  
  I2C_GenerateSTART(macI2Cx, ENABLE);
  
    I2CTimeout = I2CT_FLAG_TIMEOUT;
  /* Test on EV5 and clear it */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_MODE_SELECT))
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
        
  /* Send slave address for read */
  I2C_Send7bitAddress(macI2Cx, MPU6050_SLAVE_ADDRESS, I2C_Direction_Receiver);
  
    I2CTimeout = I2CT_FLAG_TIMEOUT;
     
  /* Test on EV6 and clear it */
  while(!I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED))
    {
    if((I2CTimeout--) == 0) return I2C_TIMEOUT_UserCallback();
   }
  
  /* While there is data to be read */
  while(NumByteToRead)  
  {
    if(NumByteToRead == 1)
    {
      /* Disable Acknowledgement */
      I2C_AcknowledgeConfig(macI2Cx, DISABLE);
      
      /* Send STOP Condition */
      I2C_GenerateSTOP(macI2Cx, ENABLE);
    }

    /* Test on EV7 and clear it */
    if(I2C_CheckEvent(macI2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED))  
    {      
      /* Read a byte from the slave */
      *pBuffer = I2C_ReceiveData(macI2Cx);

      /* Point to the next location where the byte read will be saved */
      pBuffer++; 
      
      /* Decrement the read bytes counter */
      NumByteToRead--;        
    }   
  }

  /* Enable Acknowledgement to be ready for another reception */
  I2C_AcknowledgeConfig(macI2Cx, ENABLE);
    
    return 1; //正常，返回1
}