Resolved! STM32L011U USART DMA1_Channel3 not work,but DMA1_Channel5 work
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_...