STM32H7 UART8 interrupt not working

[danelifab]

Hi everyone, I'm using a Riverdi board (STM32 10.1" Rev. 1.2) with an STM32H747XIH6, and I'm having trouble with the UART8 in single-wire mode. I can't get the interrupt callback function to be called when data is received on that port.

This board uses TouchGfx and FreeRTOS.

I'm using a test interrupt code just for the UART8, but it's not responding.

If I use the blocking function HAL_UART_Receive(...), I receive consistent data, so I don't think it's a wiring or pinout issue. 

I have checked that the signal is coming in with the oscilloscope.

I have the global interrupt enabled for the UART8.

The code I'm using is this, in freertos.c

void startUartTask(void *argument)
{
  /* USER CODE BEGIN startUartTask */
	memset(rxBuffer, 65, 128);
	HAL_HalfDuplex_EnableReceiver(&huart8);
	HAL_UARTEx_ReceiveToIdle_IT(&huart8, rxBuffer, 64);

	/* Infinite loop */
	for(;;)
	{
		//HAL_UART_Receive(&huart8, rxBuffer, 128, 120);
		osDelay(10);
	}
  /* USER CODE END startUartTask */
}

In main.c

void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{
	HAL_UARTEx_ReceiveToIdle_IT(&huart8, rxBuffer, 128);
}

I have enabled the interrupt in CubeMX for UART8 and pin J8 (UART8 TX) is configured as pullup but the callback is never called.

The task starts normally and runs.

I don't understand what's going wrong, any ideas?

Thanks

[Tesla DeLorean]

Check startup_stm32h747xx.s for UART8_IRQHandler, confirm build and linkage.

Check UART8_IRQHandler code and that it is a) reached, and b) calls into the HAL infrastructure.

Check HAL_UARTEx_RxEventCallback() is entering with huart handle pointing at your huart8 structure, verify, don't assume.

Check NVIC side configuration/recognition

Check UART8 a register level

[Tesla DeLorean]

Perhaps going to a different call-back?

Dump UART status in your UART8_IRQHandler to confirm subsequent dispatch path in HAL

[danelifab · Accepted solution]

Hi Tesla, thanks for your reply. Sorry for the delay, but I was trying a few things to troubleshoot the issue.

I found the problem. The device I connected is a GPS, it sends data continuously, and the MCU receives the HAL_UART_ERROR_ORE flag the first time the UART8 interrupt is enabled, because the GPS is sending data, but it's not being read. This flag must be cleared with __HAL_UART_CLEAR_OREFLAG(&huart8) before the interrupt is triggered.

Thanks for your time.