STM32 hal库DMA串口不定长

//切记切记要在实验板上测试，不能用软件仿真
//方法1--------------------------------------------
//main.c
uint8_t receive_buff[BUFFER_SIZE];

//usart.c
extern uint8_t receive_buff[BUFFER_SIZE];                                                //接收缓冲区
void MX_USART1_UART_Init(void)
{ // ........
   __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE);
   HAL_UART_Receive_DMA(&huart1, (uint8_t*)receive_buff, BUFFER_SIZE);
}
/* USER CODE BEGIN 1 */
//只能接受BUFFER_SIZE-1个字符
void USAR_UART_IDLECallback(UART_HandleTypeDef *huart)
{
    HAL_UART_DMAStop(&huart1);
    i++;
    
    uint8_t data_length  = BUFFER_SIZE - __HAL_DMA_GET_COUNTER(&hdma_usart1_rx);

    printf("Receive Data(length = %d): ",data_length);
    HAL_UART_Transmit(&huart1,receive_buff,data_length,0x200);
    printf("\r\n");

    memset(receive_buff,0,data_length);
    data_length = 0;
    HAL_UART_Receive_DMA(&huart1, (uint8_t*)receive_buff, BUFFER_SIZE);
}

void USER_UART_IRQHandler(UART_HandleTypeDef *huart)
{
    if(USART1 == huart1.Instance)
    {
        if(RESET != __HAL_UART_GET_FLAG(&huart1, UART_FLAG_IDLE))
        {
            __HAL_UART_CLEAR_IDLEFLAG(&huart1);
            printf("\r\nUART1 Idle IQR Detected\r\n");
            USAR_UART_IDLECallback(huart);
        }
    }
}
/* USER CODE END 1 */

//中断stm32f1xx_it.c文件内
extern void USER_UART_IRQHandler(UART_HandleTypeDef *huart);

void USART1_IRQHandler(void)
{
  /* USER CODE BEGIN USART1_IRQn 0 */
//printf("ceshi");
  /* USER CODE END USART1_IRQn 0 */
  HAL_UART_IRQHandler(&huart1);
  /* USER CODE BEGIN USART1_IRQn 1 */
//添加IDLE中断函数
USER_UART_IRQHandler(&huart1);
  /* USER CODE END USART1_IRQn 1 */
}


//方法2---------------------------------------------
//中断stm32f1xx_it.c文件内
extern void UsartReceive_IDLE(UART_HandleTypeDef *huart);
void USART1_IRQHandler(void)
{
  UsartReceive_IDLE(&huart1); //进入空闲中断
  HAL_UART_IRQHandler(&huart1);
}
//usart.c
USART_RECEIVETYPE UsartType; //定义结构体变量存储状态
//空闲中断调用函数
void UsartReceive_IDLE(UART_HandleTypeDef *huart)  
{  
    uint32_t temp;   
    if((__HAL_UART_GET_FLAG(huart,UART_FLAG_IDLE)) != RESET)  //检测空闲中断
    {   
        __HAL_UART_CLEAR_IDLEFLAG(&huart1);  
        __HAL_UART_GET_FLAG(huart,UART_FLAG_IDLE) ;
        HAL_UART_DMAStop(&huart1);  
        temp = huart1.hdmarx->Instance->CNDTR; //获取剩余dma长度 
        UsartType.RX_Size =  RX_LEN - temp;   
        UsartType.RX_flag=1;  
        HAL_UART_Receive_DMA(&huart1,UsartType.RX_pData,RX_LEN);  
    }  
} 

//usart.h
#define RX_LEN 10  
	 
typedef struct  
{  
uint8_t  RX_flag:1;        //IDLE receive flag
uint16_t RX_Size;          //receive length
uint8_t  RX_pData[RX_LEN]; //DMA receive buffer
}USART_RECEIVETYPE;  
   
extern USART_RECEIVETYPE UsartType;

//main.c
int main(void)
{
     __HAL_UART_ENABLE_IT(&huart1, UART_IT_IDLE); //开启空闲中断
  HAL_UART_Receive_DMA(&huart1, UsartType.RX_pData, RX_LEN);  //开启串口DMA接收中断
while (1)
  {
      if(UsartType.RX_flag)    	// 接收到数据的标志
      {  
           UsartType.RX_flag=0;	//清除接收到标志
           HAL_UART_Transmit(&huart1, UsartType.RX_pData, UsartType.RX_Size, 0xFFFF);
      } 
   
}