STM32F7 UART Communication Using DMA

[ASoos.1]

UART Communication Using DMA Not Working

I have Nucleo-F767ZI Rev B board and using the STM32CubeIDE Version: 1.1.0.

To test and implement UAR-DMA communication as presented in:

STM32CubeMX basics: 10.11 STM32Cube HAL labs UART - UART DMA https://www.youtube.com/watch?v=BxFYmBYBmaU

My code:

 /* USER CODE BEGIN 2 */

  HAL_UART_Transmit(&huart3, (uint8_t *)"\n\r UART3", 8,100);

  //HAL_UART_Transmit(&huart3, (uint8_t *)"\n\rHello", 7, 100);

  HAL_UART_Transmit_DMA(&huart3, (uint8_t *) "\n\rHello", 7);

  HAL_Delay(300);

  HAL_UART_Transmit(&huart3, (uint8_t *)"\n\r UART3 OK", 11, 100);

If the DMA is selected only " UART3 " is printed, the UART3 sop working thereafter.

If the polling version is selected: " UART3 Hello UART3 OK" is printed.

The same will happen if a vector is the source of the for printing.

What I am missing here?

[waclawek.jan]

https://community.st.com/s/question/0D50X0000Bmob3uSQA/dma-not-working-in-cubemx-generated-code-order-of-initialization ?

[ASoos.1]

Thank you for the quick reply.

Changed the initialization order, which resulted that the 1st UART-DMA message gets printed, but after that, the UART port stopped working for DMA or polling access. 

/* Test code */  
HAL_UART_Transmit(&huart3,mReset, sizeof(mReset),1000);  //OK
  resp = HAL_UART_Transmit_DMA(&huart3,  mesage2, sizeof(mesage2)) ;  //OK
  HAL_Delay(900); /* Insert a 0.9s delay in order to finish the print by the interrupt.*/
 
  HAL_UART_Transmit(&huart3,   pcVersionInfo, sizeof(pcVersionInfo),100);     // ??? No output
 //HAL_UART_Transmit_DMA(&huart3,   pcVersionInfo, sizeof(pcVersionInfo));  // ??? No output

[Miles1]

I had a similar issue where only the first DMA transmission would work, and found the fix was to enable HAL_UART_IRQHandler()

See this thread for more details:

https://community.st.com/s/question/0D50X00009XkgtY/dma-uart-with-hal-remain-busy-bug