F411 I2C LL Call Hangs

[HDaji.1]

I am using F411 to communicate with ADXL355 through I2C1.

I have a very strange issue:

  LL_I2C_GenerateStartCondition(I2C1);
	
  /* (1.3) Loop until Start Bit transmitted (SB flag raised) ********************/
  /* Loop until SB flag is raised  */
  while(!LL_I2C_IsActiveFlag_SB(I2C1)) { }
 
  /* (2.1) Send a 7-Bit SLAVE ADDRESS for a write request because my next step
	       is also write (putting register address on SDA line). 	 */
  LL_I2C_TransmitData8(I2C1, (dev_Addr << 1) | I2C_REQUEST_WRITE);
	
  /* (2.2) Loop until ADDR flag is raised, i.e. address is fully sent  */
  while(!LL_I2C_IsActiveFlag_ADDR(I2C1)) { }

Sometimes the above code hangs at step 2.2 when I change other part of the firmware, which is totally unrelated to this one.

FYI I made my own PCB and run this code on it.

Can anybody give any advice or hint on why it happens?

[Imen.D]

Hello @HDaji.1​ ,

Adding LL_I2C_ClearFlag_ADDR(I2C1);​ after line 12.

When your question is answered, please close this topic by choosing Select as Best. This will help other users find that answer faster.

Imen

[HDaji.1]

Hello @Imen DAHMEN​ 

Thank you for your advice. I have that LL_I2C_ClearFlag_ADDR after line 12. The issue is that it hangs at line 12, before reaching Clear Flag ADDR.

Here is the whole function:

void I2C_Read_1Byte(uint8_t dev_Addr, uint8_t reg_Addr, uint8_t *buffer) {
  /* First Round, MCU transmits only so no need to Prepare ACK ******************/
  //LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_ACK);
  
  /* (1.1) Initiate a Start condition to the Slave device ***********************/
  /* Master Generate Start condition */
  LL_I2C_GenerateStartCondition(I2C1);
	
  /* (1.3) Loop until Start Bit transmitted (SB flag raised) ********************/
  /* Loop until SB flag is raised  */
  while(!LL_I2C_IsActiveFlag_SB(I2C1)) { }
 
  /* (2.1) Send a 7-Bit SLAVE ADDRESS for a write request because my next step
	       is also write (putting register address on SDA line). 	 */
  LL_I2C_TransmitData8(I2C1, (dev_Addr << 1) | I2C_REQUEST_WRITE);
	
  /* (2.2) Loop until ADDR flag is raised, i.e. address is fully sent  */
  while(!LL_I2C_IsActiveFlag_ADDR(I2C1)) { }
	
	/* (2.3) Clear ACK.*/
	/* There is no Clear ACK function?? */
  /* (2.4) Clear ADDR flag value in ISR register */
  LL_I2C_ClearFlag_ADDR(I2C1);
	
  /* (3.1) Send data (for ADXL355, it is register address) on SDA line. */
  LL_I2C_TransmitData8(I2C1, reg_Addr);
	
  /* (3.2) Loop until Transmit data register empty flag is raised, i.e. 
	         data fully sent LL_I2C_IsActiveFlag_TXE(I2C1) == 1  */
  while(!LL_I2C_IsActiveFlag_TXE(I2C1)) { }
	
	/* (3.3) Clear ACK*/
	/* There is no Clear ACK function?? */
		
	/* According to data sheet, we need to send ReStart */
  /* (4.1) Since to receive ONE byte, we need to prepare NACK */
  LL_I2C_AcknowledgeNextData(I2C1, LL_I2C_NACK);
  
  /* (4.2) Initiate a Start condition to the Slave device ***********************/
  /* Master Generate Start condition */
  LL_I2C_GenerateStartCondition(I2C1);
	
  /* (4.3) Loop until Start Bit transmitted (SB flag raised) ********************/
  /* Loop until SB flag is raised  */
  while(!LL_I2C_IsActiveFlag_SB(I2C1)) { }
 
  /* (5.1) Send a 7-Bit SLAVE ADDRESS for a write request because my next step
	       is also write (putting register address on SDA line). */
  LL_I2C_TransmitData8(I2C1, (dev_Addr << 1) | I2C_REQUEST_READ);
	
  /* (5.2) Loop until ADDR flag is raised, i.e. address is fully sent  */
  while(!LL_I2C_IsActiveFlag_ADDR(I2C1)) { }
	
	/* (5.3) Clear ACK.*/
	/* There is no Clear ACK function?? */
	
  /* (5.4) Clear ADDR flag value in ISR register */
  LL_I2C_ClearFlag_ADDR(I2C1);
	
  /* (6.1) Loop until RXNE flag is raised  */
  while(!LL_I2C_IsActiveFlag_RXNE(I2C1)) { }
	
  /* Read character in Receive Data register.
     RXNE flag is cleared by reading data in RXDR register */
	*buffer = LL_I2C_ReceiveData8(I2C1);
	
  /* (7) End of tranfer, Data consistency are checking into Slave process *****/
  /* Generate Stop condition */
  LL_I2C_GenerateStopCondition(I2C1);
}

The above function reads one byte from a certain register in ADXL355, which is based on one of the I2C LL sample (polling) code in STM32Cube_FW_F4_V1.26.0.

I read somewhere that interrupt or DMA is recommended/supported instead of polling for I2C communication. I am going to re-write the above code with interrupt method and will post any issues or questions in this thread. I have been working with LL APIs for UART, SPI, and I2C for months, and found the I2C is very complicated to understand and implement.

[HDaji.1]

Hi @Imen DAHMEN​ 

I have coded I2C1_EV_IRQHandler, but cannot get correct result.

Do you have any advice on how to debug it?

Setting breakpoint in the middle of IRQ handler is not a good way, is it? It will break the I2C protocol.