THECODEPROGRAM

Let's get started then.

First we have to decide which I2C to use and related pins. In this project, I will use I2C1 hardware, PB6 and PB7 pins are related pins to this I2C hardware. Below code block will make configuration of the related pins to get them ready for I2C.

RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C1, ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

GPIO_InitTypeDef  GPIO_InitStructure;
I2C_InitTypeDef I2C_InitStructure;

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6 | GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_OD;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_I2C1);
GPIO_Init(GPIOB, &GPIO_InitStructure);

As you can see above we have set the pin mode as alternate function. Then we set them for I2C communication.

	//Config the I2C
	//Set the clock speed of I2C. It has to be equal with the external device
	I2C_InitStructure.I2C_ClockSpeed = 400000;
	//I2C mode
	I2C_InitStructure.I2C_Mode = I2C_Mode_I2C;
	I2C_InitStructure.I2C_DutyCycle = I2C_DutyCycle_2;
	//I2C device adress
	I2C_InitStructure.I2C_OwnAddress1 = 0x33; 
	//I2C Acknowladge configuration
	I2C_InitStructure.I2C_Ack = I2C_Ack_Enable;
	I2C_InitStructure.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
	//Enable the I2C with the prepared configuration
	I2C_Init(I2C1, &I2C_InitStructure);

	//And start the I2C 
	I2C_Cmd(I2C1, ENABLE);
	I2C_AcknowledgeConfig(I2C1, ENABLE);

Our I2C configuration is ready. Now we are going to need some functions to send and receive I2C data.

First we have to check our microprocessor and external device connected correctly. To check this we are going to start a communication transmission. Below functions will start the processor at transmitter or receiver mode. After starting these selected modes you will send the data to the external device or read the data from external device.

void Start_I2C_Transmitting(){

//For transmiting to the slave, start the data transmitting
I2C_GenerateSTART(I2C1, ENABLE);
 //Waiting for flag
 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
 //Send address to slave
 I2C_Send7bitAddress(I2C1, 0x44, I2C_Direction_Transmitter);
//And check the transmitting
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));

}

void Start_I2C_Receiving(){

//For transmiting to the slave, start the data transmitting
I2C_GenerateSTART(I2C1, ENABLE);
 //Waiting for flag
 while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_MODE_SELECT));
 //Send address to slave
 I2C_Send7bitAddress(I2C1, 0x44, I2C_Direction_Transmitter);
//And check the transmitting
while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));

}

void Send_I2C_Data(uint8_t data)
{
	I2C_SendData(I2C1, data);
	// wait for the data trasnmitted flag
	while(!I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_TRANSMITTED));
}

uint8_t Read_I2C_Data(){
	uint8_t data = I2C_ReceiveData(I2C1);
	return data;
}

void Start_I2C_Transmitting();
void Start_I2C_Receiving();
void Send_I2C_Data(uint8_t data);
uint8_t Read_I2C_Data();

	//To send data
	uint8_t _data = 0x01;
	Start_I2C_Transmitting();
	Send_I2C_Data(_data);
	I2C_GenerateSTOP(I2C1, ENABLE);
	
	//To Receive data
	uint8_t received_i2c_data[2];
	Start_I2C_Receiving();
	received_i2c_data[0] = Read_I2C_Data(I2C1);
	I2C_GenerateSTOP(I2C1, ENABLE);

Now you are ready to communicate on STM32F4 microprocessors.

That is all in this article.

Have a good I2C communicating.

Burak Hamdi TUFAN