UART5 on STM32F429IDISCOVERY not working properly in interrupt mode

[Benjamin Brammer]

Hey guys,

I am using UART5 of the board to communicate with a display from 4DSystems. I formerly used the blocking mode with HAL_UART_Transmit(..) and HAL_UARRT_Receive(..) which worked absolutelex fine. Since my orject is getting quite complex and ADC, DMA and I2C is all working in parallel, I sometimes mis message from or to the display. I think this is because I use the blocking mode which can get interrupted by DMA handling and if the situation is right this might occur directly in a bit shifting process to the UART peripheral. So to block this I want to use the HAL_UART_Transmit_IT(..) and Receive functions, so that the dma cannot interrupt an ongoing UART receive or transmit process.

Sadly my routine is not working and I honestly don't know why.

I write a command to the display with the following function:

void WriteObject_command(uint8_t objID, uint8_t objIndex, uint16_t data) //todo: tx/rx implement
{
	uint8_t command[6] = {0};
 
	command[0] = 0x01;
	command[1] = objID;
	command[2] = objIndex;
	command[3] = (data >> 8);
	command[4] = data;
	command[5] = command[0]^command[1]^command[2]^command[3]^command[4];
 
	//transmit / receive//
	 if(HAL_UART_Transmit_IT(&huart5, (uint8_t *)&command[0], 6)!= HAL_OK)
	 {
	 Error_Handler();
	 }
	 while(!UartReadyTX);
	 while(!UartReadyRX);
}

II need the blocking since I cannot issue another transmit or receive if a former command isn't processed already, thats why I wait for the two flags to be set in HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart) and in HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart).

The transmit complete is exectued just fine here is my routine:

void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
	if(huart == &huart5)
	{
		UartReadyTX = true;
		 if(HAL_UART_Receive_IT(&huart5,(uint8_t *)&uartRx[0], 10) != HAL_OK)
		 {
		 Error_Handler();
		 }
 
	}
}

but the receive complete routine gets never called and the HAL RxState of the appropriate UART handle is trapped inside BUSY_RX. I don't understand why.

Like I said the routines worked properly with the blocking mode HAL functions but now with IT functions I am trapped.

Important to notice: When I send a command to the display I get an ACK message back, thats why ever transmit needs an receive in return.

Anyone knows what my mistake is here?

best regards

Benjamin

[Benjamin Brammer]

Ok I seem to have the problem: I need to specify the correct amount of data to be received. If this isn't the case the receive complete callback is not issued. But here comes the problem: I don't always know how much data is coming back, that's why I just have a receive buffer array. Any solutions how to overcome this problem?

[Benjamin Brammer]

ok. I managed to use the UART with dma, works pretty fine so far. For a reason I don't know yet, sometimes the UART DMA receive stays inside the HAL_UART_STATE_BUSY_RX state. This seems to happen on random events, I suggest when timing from display UART doesn't meet the STM32 timing so that the display doesn't send data anymore when I want to issue a next receive. The UART5-SR looks good without an error flag set.

Any suggestions how to trace such random events correctly and find their cause?

[Benjamin Brammer]

I might have found the problem. It is no error of the UART peripheral but rather a false ISR triggering. I will check on that the next days and then solve this question..

[Piranha]

"I don't always know how much data is coming back, that's why I just have a receive buffer array. Any solutions how to overcome this problem?"

If that's still relevant:

https://stm32f4-discovery.net/2017/07/stm32-tutorial-efficiently-receive-uart-data-using-dma/

https://github.com/MaJerle/STM32_USART_DMA_RX

[Benjamin Brammer]

thanks for your post. At the moment I have to debug another custom board, but if I get stuck with that errors again I will check on your post.

THX!