Unable to receive UART data randomly

[VijayRakeshM]

Hi,

I'm using STM32L0 series and working on UART to communicate with other module and I had chosen the polling method because i know the device max response time and exact data what i'm going to receive. I was running my application for testing and it worked fine for 24 hours and then after and MCU not able to receive data even the module is responding i don't understand this scenario, can anyone please suggest what could be the problem. Thanks in advance.

Regards,

Vijay Rakesh

HAL_UART_Transmit(&huart1,A_Buff,7,200);
HAL_UART_Receive(&huart1,Rx_Buf,4,5000);  // Timeout value is 5 seconds to receive data

[S.Ma]

It is looking for trouble to process rx in polling. At least get a cyclic dma buffer in reception si there won t be any timeout issue.

[VijayRakeshM]

Hi @S.Ma​ 

Thanks for the reply, I don't have any idea on implementing DMA could please refer any document so that i can implement your suggestion and just now I have implemented UART interrupt method could this method can solve the above issue?

Regards,

Vijay Rakesh.

[S.Ma]

Check on stm32 library folders, nucleo board, usart projects.

[Tesla DeLorean]

They way you've implemented this with blocking functions is not conducive to concurrent transmit/receive. The HAL libraries just make such a mess of this rather than implementing some clean ring buffering.

My guess would be that you are getting over/under run type errors, or noise errors that don't get cleared and result in data loss. Compounded by fixed expectations about how much data will be received.

[VijayRakeshM]

Hi @Community member​ ,

Thanks for the reply, what can be the best solution for implementing concurrent transmit/receive.

Regards,

Vijay Rakesh

[Tesla DeLorean · Accepted solution]

In my work I generally use a pair of FIFO buffers, and manage the reception/transmission from those directly in the IRQ Handler. The data is inserted and removed from the FIFO in a worker or foreground task so the interrupt is not loaded with processing overhead.

[VijayRakeshM]

I was actually trying to do the same after facing the issue but i couldn't find the call back for each UART data I receive and I can only find HAL_UART_RxCpltCallback() where I need to mention how much data I'm about to receive.

[S.Ma]

HAL functions are built for expected length messages. Otherwise, use length of "1".

Otherwise use LL (low layer) especially for USART peripheral as it's pretty manageable.