Executing HAL_I2C_Master_Transmit_IT function holds SCL low.

[SomeGuyFromNH]

Hi,

I found in my search there is a similar question that went unanswered. This may be a newb question, but I'm stuck on it.

What I have found is that when executing HAL_I2C_Master_Transmit(), the data transfer happens as expected. (I happen to have green LEDs hanging on GPIO). When I execute HAL_I2C_Master_Transmit_IT(), only the 7-bit address is sent, and the Master (this program) continues to hold the SCL line low.

If someone could explain what I am doing wrong with the HAL_I2C_Master_Transmit_IT() program, that would be much appreciated!

	 //Turn on the two green LEDs on the LTC4306's GPIO
	 data[0] = 0x01;
	 data[1] = 0b00001111;
	 status = HAL_I2C_Master_Transmit(&hi2c1, ltc4306_Address, data, 2, 1 );
 
	 //Turn off the two green LEDs on the LTC4306's GPIO
	 data[0] = 0x01;
	 data[1] = 0b00111111;
	 status = HAL_I2C_Master_Transmit(&hi2c1, ltc4306_Address, data, 2, 1 );
 
	 //Turn on the two green LEDs on the LTC4306's GPIO
	 data[0] = 0x01;
	 data[1] = 0b00001111;
	 status = HAL_I2C_Master_Transmit_IT(&hi2c1, ltc4306_Address, data, 2 ); //This returns HAL_OK... but the master (this program) is holding SCL low after having transmitted the 7-bit address.
	 HAL_I2C_MasterTxCpltCallback(&hi2c1); // SCL still being held low after execution of this line. Doesn't seem to help. 

[txnghia]

You probably missed the I2C1 interrupt handler function. I had a similar problem. After I added the interrupt handler function, the problem is fixed.

I added the interrupt handler to "stm32f0xx_it.c" file as below. (I use STM32F072RBT6 chip)

void I2C1_IRQHandler(void)

{

 if (hi2c1.Instance->ISR & (I2C_FLAG_BERR | I2C_FLAG_ARLO | I2C_FLAG_OVR)) {

  HAL_I2C_ER_IRQHandler(&hi2c1);

 } else {

  HAL_I2C_EV_IRQHandler(&hi2c1);

 }

}

And also added I2C1 interrupt initialization to HAL_I2C_MspInit() function as below

void HAL_I2C_MspInit(I2C_HandleTypeDef* hi2c)

{

 GPIO_InitTypeDef GPIO_InitStruct = {0};

 if(hi2c->Instance==I2C1)

 {

  __HAL_RCC_GPIOB_CLK_ENABLE();

  /**I2C1 GPIO Configuration

  PB8   ------> I2C1_SCL

  PB9   ------> I2C1_SDA

  */

  GPIO_InitStruct.Pin = GPIO_PIN_8|GPIO_PIN_9;

  GPIO_InitStruct.Mode = GPIO_MODE_AF_OD;

  GPIO_InitStruct.Pull = GPIO_PULLUP;

  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;

  GPIO_InitStruct.Alternate = GPIO_AF1_I2C1;

  HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

  /* Peripheral clock enable */

  __HAL_RCC_I2C1_CLK_ENABLE();

  /* I2C1 interrupt Init */

  HAL_NVIC_SetPriority(I2C1_IRQn, 0, 0);

  HAL_NVIC_EnableIRQ(I2C1_IRQn);

 }

[HYih.1]

I am using STM32H745I-DISCO board. STM32CubeMX v6.5.0. generates interrupt handlers:

void I2Cx_EV_IRQHandler(void)

void I2Cx_ER_IRQHandler(void)

and MspInit function:

void HAL_I2C_MspInit(I2C_HandleTypeDef* hi2c)