Interrupt doesn't work when UART received on STM32F469I DISCO.

[SNEM.1]

I configured the UART: huart6. I set the global interrupt and I use touchgfx designer (so RTOS as well), maybe that is the reason I can't set the preemption priority lower than 5 for the UART interrupt. The problem is that I can send messages to ESP8266, but I can't receive the messages from the ESP... Here is the code form the interrupt uart receiving and the callback function:

 /* USER CODE BEGIN 2 */

 HAL_UART_Receive_IT(&huart6, buff_Rx, 13);

 /* USER CODE END 2 */

.

.

.

/* USER CODE BEGIN 4 */

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)

{

CpltDone = 1;

HAL_UART_Receive_IT(&huart6, buff_Rx, 13);

   HAL_GPIO_WritePin(GPIOG, GPIO_PIN_11, GPIO_PIN_RESET);

}

/* USER CODE END 4 */

If I put a breakpoint into the callback function the code never stops and if I use breakpoint at another place I can't see values in "buff_Rx" buffer. I examined the line with logic analyzer and the values are correct on the line... but I never get them...

What can be the problem?

• ESP IO voltage is 3v3 and the STM's Arduino compatible pins are 5V and that could be the reason?? (but if I use the SPI communication it works well..)
• Or the problem is the priority of UART interrupt?
• Or something else?

Can anybody help me?

Thanks a lot!

[Guenael Cadier]

Hi @SNEM.1​ 

Just some ideas.

When you set your breakpoint at "another place", could you check the content of the SR register of your UART/USART instance ? Just to check if the Overrun flag (ORE) is not raised, as this could prevent reception.

You could also check if ErrorCallback is executed.

[SNEM.1]

Thanks for the advice!

How my code actually works: when I send a message via UART/USART the other MCU makes its job and send back a message (sensor values) to the STM.

Based on your words I tried to see what happens in the registers but unfortunately I can't stop the running when I should receive the values.

So I set a breakpoint to the beginning of a "send message function" and when I call this 2nd time it's sure that I had to receive some values already.

Some interesting things (for me,because I don't really understand why it works this way):

• DR's value is always 0x17
• In CR1 the RXNEIE is 0 (but it should be 1 to enable interrupt, am I right?)
• After I sent the message and I stop the running at the very next instruction the registers value are the next: CTS 0, LBD 1, TXE 1, TC 1, RXNE 1, IDLE 1, ORE 1, and the others are 0 (and DR = 0x17)

It means that the message arrive in the shift register and try to transmit to the DR but there is some error? Or it means anything else? And I set the global interrupt for the USART but RXNEIE is 0...Why? :\ I'm not really experienced in this area. Thanks again for your advices!

[Karl Yamashita]

upload your IOC file

[SNEM.1]

I hope it's not so wrong :\ The base is generated by Touchgfx and I added USART6 and (if I remember well) the SPI2.

[SNEM.1]

Now I received some values somehow... but I had to restart the system and after that the problem comes again... Maybe some synchronization problem?

[Tesla DeLorean]

Clear the overrun error *ORE"

[SNEM.1]

Now it seems to be good. What I had to do:

I didn't disconnect the UART lines while I restarted the STM board :D It looks like some synchronization problem... Can anybody explain this? 🙂