用STM32F030做串口通讯,发送端经常未知长度，后不能再次接收研究了好久，參考网上有DMA接收但是超过最大值也会出错需重置DMA。    UART DMA   https://www.stmcu.org.cn/module/forum/thread-620624-1-1.html   
因 STM32F030F4P6 FLASH 太小用DMA会多增加500字节。

1.在usart.c /* USER CODE BEGIN 1 */处增加代码方便后续cube配置不会被清除。

1. /* USER CODE BEGIN 1 */
   
2. void UsartReceive_IDLE(UART_HandleTypeDef *huart)
   
3. {  
   
4.   uint32_t isrflags   = READ_REG(huart->Instance->ISR);
   
5.   uint32_t cr1its     = READ_REG(huart->Instance->CR1);
   
6. 
   
7.   /* UART Idle interrupt occurred   --------------------------------------------*/
   
8.   if (((isrflags & USART_ISR_IDLE) != RESET) && ((cr1its & USART_CR1_IDLEIE) != RESET))
   
9.   {
   
10.     __HAL_UART_CLEAR_IDLEFLAG(huart);
    
11.     __HAL_UART_DISABLE_IT(huart, UART_IT_IDLE);
    
12.     HAL_UART_RxIdleCallback(huart);
    
13.     return;
    
14.   }
    
15. }
    
16. /**
    
17.   * @brief  Rx Idle callbacks.
    
18.   * @param  huart: Pointer to a UART_HandleTypeDef structure that contains
    
19.   *                the configuration information for the specified UART module.
    
20.   * @retval None
    
21.   */
    
22. __weak void HAL_UART_RxIdleCallback(UART_HandleTypeDef *huart)
    
23. {
    
24.   /* Prevent unused argument(s) compilation warning */
    
25.   UNUSED(huart);
    
26.   /* NOTE: This function should not be modified, when the callback is needed,
    
27.            the HAL_UART_RxIdleCallback can be implemented in the user file
    
28.    */
    
29. }
    
30. /* USER CODE END 1 */

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2.在usart.h /* USER CODE BEGIN Prototypes */ 新增

1. /* USER CODE BEGIN Prototypes */
   
2. void UsartReceive_IDLE(UART_HandleTypeDef *huart);
   
3. void HAL_UART_RxIdleCallback(UART_HandleTypeDef *huart);
   
4. /* USER CODE END Prototypes */

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3.在stm32f0xx_it.c /* USER CODE BEGIN 0 */ 新增

1. /* USER CODE BEGIN 0 */
   
2. #include "usart.h"
   
3. /* USER CODE END 0 */

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4.在stm32f0xx_it.c void USART1_IRQHandler(void) 新增

1. void USART1_IRQHandler(void)
   
2. {
   
3.   /* USER CODE BEGIN USART1_IRQn 0 */
   
4.   UsartReceive_IDLE(&huart1);    //新增
   
5.   /* USER CODE END USART1_IRQn 0 */
   
6.   HAL_UART_IRQHandler(&huart1);
   
7.   /* USER CODE BEGIN USART1_IRQn 1 */
   
8. 
   
9.   /* USER CODE END USART1_IRQn 1 */
   
10. }

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5.1在main.c /* USER CODE BEGIN Includes */ 新增

1. /* USER CODE BEGIN Includes */
   
2. #include "string.h"
   
3. /* USER CODE END Includes */

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5.2在main.c /* USER CODE BEGIN PV */ 新增

1. /* USER CODE BEGIN PV */
   
2. /* Private variables ---------------------------------------------------------*/
   
3. #define RECEIVELEN 16
   
4. u8  uart1_Rx_Temp;            //接收缓冲
   
5. u8  uart1_RxBuff[RECEIVELEN]; //接收缓冲
   
6. u16 uart1_Rx_Count;           //接收长度
   
7. /* USER CODE END PV */

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5.3在main.c   /* USER CODE BEGIN 2 */ //新增

1.   /* USER CODE BEGIN 2 */
   
2.   HAL_UART_Receive_IT(&huart1, (uint8_t *)&uart1_Rx_Temp, 1);
   
3.   /* USER CODE END 2 */

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5.4在main.c /* USER CODE BEGIN 4 */ 新增

1. /* USER CODE BEGIN 4 */
   
2. //UART1
   
3. void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
   
4. {
   
5.   if (huart->Instance == USART1)
   
6.   {
   
7.     uart1_RxBuff[uart1_Rx_Count] = uart1_Rx_Temp;
   
8.     HAL_UART_Receive_IT(huart, (uint8_t *)&uart1_Rx_Temp, 1);
   
9.     if (++uart1_Rx_Count >= RECEIVELEN)
   
10.     {
    
11.       uart1_Rx_Count--;
    
12.     }
    
13.     __HAL_UART_CLEAR_IDLEFLAG(&huart1);
    
14.     __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE);
    
15.   }
    
16. }
    
17. void HAL_UART_RxIdleCallback(UART_HandleTypeDef *huart)
    
18. {
    
19.   if (huart->Instance == USART1)
    
20.   {
    
21.     __HAL_UART_CLEAR_IDLEFLAG(huart);
    
22.     __HAL_UART_ENABLE_IT(huart, UART_IT_IDLE);
    
23. 
    
24.     HAL_UART_Transmit(&huart1, (uint8_t *)&uart1_RxBuff, RECEIVELEN,0xFFFF);
    
25.     memset(uart1_RxBuff,0x00,sizeof(uart1_RxBuff));                            //清空数组
    
26.     uart1_Rx_Count = 0;
    
27.   }
    
28. }
    
29. /* USER CODE END 4 */

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參考 https://www.stmcu.org.cn/module/forum/thread-620532-1-1.html?or5