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I am trying to use the STM32F4 discovery board as a master to communicate to a sensor using I2C. I am using the std periph library to do this but for some reason I am unable to get anything going through the SCL and SDA lines. From reading through the stf periph header files and other examples I have seen online it does not seem that I am doing anything wrong or forgetting a step. Below I have Included all of my I2C code: 

#define I2CTransmitter       0
#define I2CReciever          1
#define I2CAckEnable         1
#define I2CAckDisable        0

void I2CInit() {
    I2C_InitTypeDef I2CInitStruct;
    GPIO_InitTypeDef  GPIO;

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

    //Configure and initialize the GPIOs
    GPIO.GPIO_Pin = GPIO_Pin_6;
    GPIO.GPIO_Mode = GPIO_Mode_AF;
    GPIO.GPIO_Speed = GPIO_Speed_100MHz;
    GPIO.GPIO_OType = GPIO_OType_OD;
    GPIO.GPIO_PuPd  = GPIO_PuPd_UP;
    GPIO_Init(GPIOB, &GPIO);

    GPIO.GPIO_Pin = GPIO_Pin_7;
    GPIO_Init(GPIOB, &GPIO);

    //Connect GPIO pins to peripheral
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource6, GPIO_AF_I2C1);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource7, GPIO_AF_I2C1);

    I2CInitStruct.I2C_ClockSpeed = 100000;
    I2CInitStruct.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;
    I2CInitStruct.I2C_Mode = I2C_Mode_I2C;
    I2CInitStruct.I2C_OwnAddress1 = 0x00;
    I2CInitStruct.I2C_Ack = I2C_Ack_Enable;
    I2CInitStruct.I2C_DutyCycle = I2C_DutyCycle_2;

    I2C_Init(I2C1, &I2CInitStruct);

    I2C_Cmd(I2C1, ENABLE);
}

uint8_t I2CRead(uint8_t address, uint8_t reg) {
    uint8_t data;
    I2CStart(address, I2CTransmitter, I2CAckEnable);
    I2CWriteData(reg);
    I2CStart(address, I2CReciever, I2CAckDisable);
    data = I2CReadNAck();
    I2CStop();
    return data;
}

void I2CWrite(uint8_t address, uint8_t reg, uint8_t data) {
    I2CStart(address, I2CTransmitter, I2CAckEnable);
    I2CWriteData(reg);
    I2CWriteData(data);
    I2CStop();
}

void I2CStart(uint8_t address, uint8_t direction, uint8_t ack) {
    I2C_GenerateSTART(I2C1, ENABLE);
    I2C_Send7bitAddress(I2C1, address, direction);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_SLAVE_BYTE_RECEIVED));
}

void I2CStop() {
    I2C_GenerateSTOP(I2C1, ENABLE);
}

void I2CWriteData(uint8_t data) {
    I2C_SendData(I2C1, data);
    while(!I2C_CheckEvent(I2C1, I2C_EVENT_SLAVE_BYTE_RECEIVED));
}

uint8_t I2CReadAck() {
    uint8_t data;

    I2C_AcknowledgeConfig(I2C1, ENABLE);
    while( !I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED) );
    data = I2C_ReceiveData(I2C1);
    return data;
}

uint8_t I2CReadNAck() {
    uint8_t data;
    I2C_AcknowledgeConfig(I2C1, DISABLE);
    I2C_GenerateSTOP(I2C1, ENABLE);
    while( !I2C_CheckEvent(I2C1, I2C_EVENT_MASTER_BYTE_RECEIVED) );
    data = I2C_ReceiveData(I2C1);
    return data;
}

The code is used in the main function by simply calling I2CInit() and then calling I2CWrite() in a while loop for testing. Thank you in advance for any help!

Sumeet K
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  • Have you tried changing the pull-up resistor setting? Try `GPIO_PuPd_NOPULL` for the `GPIO.GPIO_PuPd` field. Additionally, what is the device you're trying to interface to? – mban May 26 '17 at 13:50
  • Another thought, try moving around the configuration sequence to: `GPIO_PinAFConfig(...)`, `GPIO_Init(...)`, `RCC_AXB1PeriphClockCmd(...)`, `I2C_Init/Cmd`. Specifically, I believe the AF configuration needs to happen before the GPIO configuration. – mban May 26 '17 at 14:05
  • Hey mban! Thanks for the help but I was actually able to figure it out shortly after posting this and forgot to mention that the issue was resolved before you posted the answer! In the end it was moving around the config sequence that helped :) – Sumeet K Jun 02 '17 at 14:30

0 Answers0