Unable to see why I2C3 is not functioning?

[Rogers.Gary]

Posted on May 03, 2015 at 00:30

Hi,

I have been looking at this for hours, but cannot determine why I cannot get the I2C3 operating, even getting a pulse from the SCK line. I am using an STM32F4 device, with an ST LIS3DML sensor. Both SCK and SDA are physically pulled to Vdd with a  10K resistor. GPIO and call to I2C init is below: void init_I2C3(void) {     GPIO_InitTypeDef GPIO_InitStruct;     I2C_InitTypeDef I2C_InitStruct;          // enable APB1 peripheral clock for I2C3     RCC_APB1PeriphClockCmd(RCC_APB1Periph_I2C3, ENABLE);     // enable clock for SCL pin     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);     // enable clock for SDA pin     RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOC, ENABLE);         GPIO_InitStruct.GPIO_Pin = GPIO_Pin_8;                GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;             GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;         GPIO_InitStruct.GPIO_OType = GPIO_OType_OD;             GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;         GPIO_Init(GPIOA, &GPIO_InitStruct);                     GPIO_InitStruct.GPIO_Pin = GPIO_Pin_9;               GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF;             GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;         GPIO_InitStruct.GPIO_OType = GPIO_OType_OD;             GPIO_InitStruct.GPIO_PuPd = GPIO_PuPd_NOPULL;         GPIO_Init(GPIOC, &GPIO_InitStruct);                          // Connect I2C3 pins to AF       GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_I2C3);    // SCL     GPIO_PinAFConfig(GPIOC, GPIO_PinSource9, GPIO_AF_I2C3); // SDA          // configure I2C3     I2C_InitStruct.I2C_ClockSpeed = 100000;         // 100kHz     I2C_InitStruct.I2C_Mode = I2C_Mode_I2C;             I2C_InitStruct.I2C_DutyCycle = I2C_DutyCycle_2;     I2C_InitStruct.I2C_OwnAddress1 = 0x00;                 I2C_InitStruct.I2C_Ack = I2C_Ack_Disable;             I2C_InitStruct.I2C_AcknowledgedAddress = I2C_AcknowledgedAddress_7bit;     I2C_Init(I2C3, &I2C_InitStruct);                          // enable I2C3     I2C_Cmd(I2C3, ENABLE); }Below is the I2C start, and the I2C send: void I2C_start(I2C_TypeDef* I2Cx, uint8_t address, uint8_t direction) {     // wait until I2C1 is not busy anymore     while(I2C_GetFlagStatus(I2Cx, I2C_FLAG_BUSY));       // Send I2C1 START condition     I2C_GenerateSTART(I2Cx, ENABLE);            // wait for I2C1 EV5 --> Slave has acknowledged start condition     while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_MODE_SELECT));              // Send slave Address for write     I2C_Send7bitAddress(I2Cx, address, direction);            /* wait for I2C1 EV6, check if      * either Slave has acknowledged Master transmitter or      * Master receiver mode, depending on the transmission      * direction      */     if(direction == I2C_Direction_Transmitter){         while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_TRANSMITTER_MODE_SELECTED));     }     else if(direction == I2C_Direction_Receiver){         while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_RECEIVER_MODE_SELECTED));     } } void I2C_write(I2C_TypeDef* I2Cx, uint8_t data) {     I2C_SendData(I2Cx, data);     // wait for I2C1 EV8_2 --> byte has been transmitted     while(!I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_TRANSMITTED)); } uint8_t I2C_read_ack(I2C_TypeDef* I2Cx){     // enable acknowledge of recieved data     I2C_AcknowledgeConfig(I2Cx, ENABLE);     // wait until one byte has been received     while( !I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED) );     // read data from I2C data register and return data byte     uint8_t data = I2C_ReceiveData(I2Cx);     return data; } uint8_t I2C_read_nack(I2C_TypeDef* I2Cx){     // disabe acknowledge of received data     // nack also generates stop condition after last byte received     // see reference manual for more info     I2C_AcknowledgeConfig(I2Cx, DISABLE);     I2C_GenerateSTOP(I2Cx, ENABLE);     // wait until one byte has been received     while( !I2C_CheckEvent(I2Cx, I2C_EVENT_MASTER_BYTE_RECEIVED) );     // read data from I2C data register and return data byte     uint8_t data = I2C_ReceiveData(I2Cx);     return data; } From main, I call: &sharpdefine LIS3MDL_ADDRESS      0x1C &sharpdefine LIS3MDL_WHO_AM_I     0x0F  // should return 0x3D     init_I2C3();     I2C_start(I2C3, LIS3MDL_ADDRESS<<1, I2C_Direction_Transmitter);     I2C_write(I2C3, LIS3MDL_WHO_AM_I);     //I2C_read_nack(I2C3);     I2C_read_ack(I2C3); However, when scoping the SCK line, there is never a clock burst from the STM32F4. In fact, it hangs the processor if I try to use either read call above. Any idea of what the problem might be? Thank you for any help... #stm32f4 #i2c3