Can't receive data on UART7 in STM32H7S78-DK while using UART4

[Mehulrana511]

Hello,

I am using the STM32H7S78-DK board and STM32CubeIDE for development. In my application, I am working with UART communication between UART4 and UART7.

Objective:

1. I am sending data from UART4 (connected to the Virtual COM port on the board).
2. The data is transmitted from UART4 to UART7.
3. After sending the data, I expect a response from UART7, but I am unable to receive it.

Steps I Follow:

1. Initially, I used the HAL_UART_Receive_IT function for UART7 reception. However, upon reviewing several posts and technical documents, I realized that HAL_UART_Receive_IT is only suitable for known-length data and not for unknown-length data.
2. Based on the reference example provided here, I implemented HAL_UARTEx_ReceiveToIdle_IT for idle-line detection.

Issue Faced:

Despite implementing HAL_UARTEx_ReceiveToIdle_IT, I am still unable to receive any response from UART7.

Here is my code for reference,

/* USER CODE BEGIN PV */
#define RX_BUFFER_SIZE      20
#define RX_BUFFER_SIZE_7    50

uint8_t rxBuffer[RX_BUFFER_SIZE] = {0}; // Buffer to store received data
uint8_t rxBuffer7[RX_BUFFER_SIZE_7] = {0}; // Buffer to store received data


osThreadId_t uartTaskHandle;
const osThreadAttr_t uartTask_attributes =
{
    .name = "uartTask",
    .priority = (osPriority_t)osPriorityNormal,
    .stack_size = 512 * 4,
};

void UART_Print(const char* message)
{
   // Transmit the string data over UART
   HAL_UART_Transmit(&huart4, (uint8_t*)message, strlen(message), HAL_MAX_DELAY);
}


void SendDataOnUART7(uint8_t *pData)
{
	uint8_t TxData[20];

	uint16_t length = (uint16_t)pData[0];

	memcpy(TxData, &pData[1],length);

	// Transmit the string data over UART
	HAL_UART_Transmit(&huart7,TxData, length, HAL_MAX_DELAY);
}


void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{
	if (huart->Instance == huart7.Instance)
	{
		// Transmit the string data over UART
		printf("Received data on uart7: %s\n\r", rxBuffer7);

		HAL_UARTEx_ReceiveToIdle_IT(&huart7, rxBuffer7, RX_BUFFER_SIZE_7);
	}
}


void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	if (huart->Instance == huart4.Instance)
	{
		// Print received message
		printf("Received: %s\n\r", rxBuffer);

		SendDataOnUART7(rxBuffer);

		memset(rxBuffer, 0, RX_BUFFER_SIZE);

		// Re-enable UART interrupt for the full buffer to receive more data
		HAL_UART_Receive_IT(&huart4, rxBuffer, RX_BUFFER_SIZE);
	}

}


/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{

  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

  /* MPU Configuration--------------------------------------------------------*/
  MPU_Config();

  /* Enable the CPU Cache */

  /* Enable I-Cache---------------------------------------------------------*/
  SCB_EnableICache();

  /* Enable D-Cache---------------------------------------------------------*/
  SCB_EnableDCache();

  /* MCU Configuration--------------------------------------------------------*/

  /* Update SystemCoreClock variable according to RCC registers values. */
  SystemCoreClockUpdate();

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();


  MX_GPIO_Init();
  MX_HPDMA1_Init();
  MX_LTDC_Init();
  MX_CRC_Init();
  MX_DMA2D_Init();
  MX_JPEG_Init();
  MX_FLASH_Init();
  MX_I2C1_Init();
  MX_GPU2D_Init();
  MX_ICACHE_GPU2D_Init();
  MX_UART4_Init();
  MX_UART7_Init();
  
  UART_Print("Start...TouchGFX...Project\n\r");
  printf("Hello_STM32H7S78-DK!\n\r");

  /* Enable UART4 interrupt mode */
  //Make sure that the data sent is exactly 20 bytes, as the RX_BUFFER_SIZE is set to 20. If the data is not 20 bytes, it will not work properly!
  HAL_UART_Receive_IT(&huart4, rxBuffer, RX_BUFFER_SIZE); 
  HAL_UARTEx_ReceiveToIdle_IT(&huart7, rxBuffer7, RX_BUFFER_SIZE_7);


  MX_TouchGFX_Init();
  /* Call PreOsInit function */
  MX_TouchGFX_PreOSInit();

  osKernelInitialize();

  defaultTaskHandle = osThreadNew(StartDefaultTask, NULL, &defaultTask_attributes);

  /* creation of TouchGFXTask */
  TouchGFXTaskHandle = osThreadNew(TouchGFX_Task, NULL, &TouchGFXTask_attributes);

  uartTaskHandle = osThreadNew(UART_Task, NULL, &uartTask_attributes);


  /* Start scheduler */
  osKernelStart();

  while (1)
  {

  }
  /* USER CODE END 3 */
}

I would appreciate any guidance or example code to resolve this issue.

Best regards,
Mehul

[Karl Yamashita]

So I've tested on the Nucleo-H723 and UART7 is interrupting. 

The first time I tested, it was over a year ago. Possibly the FW package back then could have had a bug? I never did check the generated code for bugs back then.

But with STM32CubeIDE 1.16.1 and the latest FW package, UART7 doesn't show any issue with interrupts when receiving data.