STM32L011U USART DMA1_Channel3 not work,but DMA1_Channel5 work

[ElectronicABC]

void HAL_UART_MspInit(UART_HandleTypeDef* huart)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(huart->Instance==USART2)
{
/* USER CODE BEGIN USART2_MspInit 0 */

/* USER CODE END USART2_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_USART2_CLK_ENABLE();

__HAL_RCC_GPIOB_CLK_ENABLE();
/**USART2 GPIO Configuration
PB6 ------> USART2_TX
PB7 ------> USART2_RX
*/
GPIO_InitStruct.Pin = GPIO_PIN_6|GPIO_PIN_7;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF0_USART2;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

/* USART2 DMA Init */
/* USART2_RX Init */
hdma_usart2_rx.Instance = DMA1_Channel3;// DMA1_Channel5  work 
hdma_usart2_rx.Init.Request = DMA_REQUEST_4;
hdma_usart2_rx.Init.Direction = DMA_PERIPH_TO_MEMORY;
hdma_usart2_rx.Init.PeriphInc = DMA_PINC_DISABLE;
hdma_usart2_rx.Init.MemInc = DMA_MINC_ENABLE;
hdma_usart2_rx.Init.PeriphDataAlignment = DMA_PDATAALIGN_BYTE;
hdma_usart2_rx.Init.MemDataAlignment = DMA_MDATAALIGN_BYTE;
hdma_usart2_rx.Init.Mode = DMA_NORMAL;
hdma_usart2_rx.Init.Priority = DMA_PRIORITY_VERY_HIGH;
if (HAL_DMA_Init(&hdma_usart2_rx) != HAL_OK)
{
Error_Handler();
}

__HAL_LINKDMA(huart,hdmarx,hdma_usart2_rx);

/* USART2 interrupt Init */
HAL_NVIC_SetPriority(USART2_IRQn, 2, 0);
HAL_NVIC_EnableIRQ(USART2_IRQn);
/* USER CODE BEGIN USART2_MspInit 1 */

/* USER CODE END USART2_MspInit 1 */
}

}  



void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{
//recv size
uint8_t send_buf[2];
send_buf[0]=Size&0xFF;
send_buf[1]=Size>>8;
HAL_UART_Transmit(huart,send_buf,2,20);
HAL_UARTEx_ReceiveToIdle_DMA(&huart2,buf,32);
}

int main(void)
{
  /* USER CODE BEGIN 1 */

  /* USER CODE END 1 */

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

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

  /* USER CODE BEGIN Init */

  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();
  /* USER CODE BEGIN 2 */

  HAL_UARTEx_ReceiveToIdle_DMA(&huart2,buf,32);//start recv
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

Edited by ST Moderator to apply source code formatting - please see this guideline How to insert source code.

[Imen.D]

Hello @ElectronicABC,

When USART2 uses DMA channel 3 for data reception, data transfers are blocked after the first byte has been
received. As a result, DMA channel 3 cannot be used for USART2 data reception.

This is mentioned in the STM32L011x3 errata sheet:

"

2.11.6 DMA channel 3 (CH3) not functional when USART2_RX used for data reception
Description
When USART2 uses DMA channel 3 for data reception, data transfers are blocked after the first byte has been
received. As a result, DMA channel 3 cannot be used for USART2 data reception.
Workaround
Use DMA channel 5 (CH5) for USART2 data reception.

"