I2C（Inter－Integrated Circuit）总线是一种两线式串行总线，用于连接微控制器及其外围设备。和SPI一样，也是一种常用的串行通信方式。

STM32微控制器提供硬件I2C，对它进行相应配置就可以用来进行多个设备之间的通信。

使用步骤：

1. Enable peripheral clock 

2. Enable SDA, SCL and SMBA (when used) GPIO clocks 

3. Peripherals alternate function: Call GPIO_Init() function.

4. Program the Mode, Timing , Own address, Ack and Acknowledged Address using the I2C_Init() function.

5. Enable the NVIC and the corresponding interrupt  if you need to use interrupt mode.

7. When using the DMA mode Configure the DMA 

8. Enable the I2C using the I2C_Cmd() function.

9. Enable the DMA when using DMA mode in the transfers.

基于STM32F3discovery开发板

MCU：STM32F303VC作为主机

从机”LSM303DLHC加速度计/磁强计

使用I2C1，引脚：PB6—I2C1_SCL，PB7—I2C1_SDA

代码：

void I2C_Config(void)

{

I2C_InitTypeDef I2C_InitStructure;

GPIO_InitTypeDef GPIO_InitStructure;

RCC_AHBPeriphClockCmd(I2C_GPIO_CLK, ENABLE);

RCC_APB1PeriphClockCmd(LSM303DLHC_I2C_CLK, ENABLE);

GPIO_PinAFConfig(I2C_GPIO_PORT, I2C_SCK_SOURCE, I2C_SCK_AF);

GPIO_PinAFConfig(I2C_GPIO_PORT, I2C_SDA_SOURCE, I2C_SDA_AF);

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;

GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;

GPIO_InitStructure.GPIO_PuPd  = GPIO_PuPd_NOPULL;//GPIO_PuPd_DOWN;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_InitStructure.GPIO_Pin =I2C_SCK_PIN;

GPIO_Init(I2C_GPIO_PORT, &GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin =I2C_SDA_PIN;

GPIO_Init(I2C_GPIO_PORT, &GPIO_InitStructure);

I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;

I2C_InitStructure.I2C_AnalogFilter= I2C_AnalogFilter_Enable;

I2C_InitStructure.I2C_DigitalFilter= 0x00;

I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;

I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;

I2C_InitStructure.I2C_OwnAddress1=0x00;

I2C_InitStructure.I2C_Timing = 0x00902025;

I2C_Init(LSM303DLHC_I2C,&I2C_InitStructure);

I2C_Cmd(LSM303DLHC_I2C, ENABLE);

}

uint16_t LSM303DLHC_myRead(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer, uint16_t NumByteToRead)

{

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_BUSY)!=RESET);

I2C_TransferHandling(LSM303DLHC_I2C,DeviceAddr,1,I2C_SoftEnd_Mode,I2C_Generate_Start_Write);

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_TXIS)==RESET);

if(NumByteToRead>1)

      RegAddr |= 0x80;            //读多字节指令

 I2C_SendData(LSM303DLHC_I2C,(u8)RegAddr);

 while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_TC));

 I2C_TransferHandling(LSM303DLHC_I2C,DeviceAddr,NumByteToRead,I2C_AutoEnd_Mode,I2C_Generate_Start_Read);

while(NumByteToRead>0)

{

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_RXNE)==RESET);

*pBuffer = I2C_ReceiveData(LSM303DLHC_I2C);

pBuffer++;

NumByteToRead--;

}

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_STOPF)==RESET);

I2C_ClearFlag(LSM303DLHC_I2C,I2C_FLAG_STOPF);

return 1;

}

uint16_t LSM303DLHC_myWrite(uint8_t DeviceAddr, uint8_t RegAddr, uint8_t* pBuffer)

{

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_BUSY)!=0);

I2C_TransferHandling(LSM303DLHC_I2C,DeviceAddr,1,I2C_SoftEnd_Mode,I2C_Generate_Start_Write);

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_TXIS)==0);

I2C_SendData(LSM303DLHC_I2C,RegAddr);

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_TC)==0);

I2C_TransferHandling(LSM303DLHC_I2C,DeviceAddr,1,I2C_AutoEnd_Mode,I2C_Generate_Start_Write);

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_TXIS)==0);

I2C_SendData(LSM303DLHC_I2C,*pBuffer);

while(I2C_GetFlagStatus(LSM303DLHC_I2C,I2C_FLAG_STOPF)==0);

I2C_ClearFlag(LSM303DLHC_I2C,I2C_FLAG_STOPF);

return 1;

}

然后根据需要设置LSM303DLHC初始化参数，就可以用上面的读数据函数不断读取传感器内数据寄存器的值，进行后续数据处理。