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--) == ) 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--) == ) 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--) == ) 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--) == ) return I2C_TIMEOUT_UserCallback();
   } 

   /* Send STOP condition */
   I2C_GenerateSTOP(macI2Cx, ENABLE);

     return ; //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--) == ) 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--) == ) 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--) == ) 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--) == ) 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--) == ) 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--) == ) return I2C_TIMEOUT_UserCallback();
    }

   /* While there is data to be read */
   while(NumByteToRead)
   {
     if(NumByteToRead == )
     {
       /* 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 ; //正常，返回1
 }