想要請問，當我利用DMA做USART傳輸時，當我定義BufferSize大小為DataLen時，當我從PC端寫入一串數據如"123456"，但是傳送出來的數據一定是"0123456012"剛好填滿我設定的buffer 大小。請問是哪裡出問題呢?謝謝我的程式如下：


#define DataLen 10
u8 SendBuff[DataLen];
u8 RecviceBuff[DataLen];


void USART_DMA_Configuration(void)
{
    DMA_InitTypeDef DMA_InitStructure;
    DMA_DeInit(DMA1_Channel4);  
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)SendBuff;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
    DMA_InitStructure.DMA_BufferSize = DataLen;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel4, &DMA_InitStructure);
    DMA_ITConfig(DMA1_Channel4, DMA_IT_TC, ENABLE);
    DMA_ITConfig(DMA1_Channel4, DMA_IT_TE, ENABLE);
    USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
    DMA_Cmd(DMA1_Channel4, DISABLE);   
    DMA_DeInit(DMA1_Channel5);
    DMA_InitStructure.DMA_PeripheralBaseAddr = USART1_DT_Base;
    DMA_InitStructure.DMA_MemoryBaseAddr =  (uint32_t) RecviceBuff;  
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
    DMA_InitStructure.DMA_BufferSize = DataLen;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel5, &DMA_InitStructure);
    DMA_Cmd(DMA1_Channel5, ENABLE);  

/*****************************************************************/
**************主流程  PC端寫入資料並由SMT32F1輸出至PC端
    if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)
    {
        DMA_Cmd(DMA1_Channel5, DISABLE);
        DATA_LEN=DataLen - DMA_GetCurrDataCounter(DMA1_Channel5);
        if(DATA_LEN > 0)
        {   
            for(i=0;i<DATA_LEN;i++)  
            {
               SendBuff[i]= RecviceBuff[i];      // Let Memory receive data copy to Send memory
            }
            DMA_Cmd(DMA1_Channel4, DISABLE);
            DMA1_Channel4->CNDTR=DATA_LEN;
            USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
            DMA_Cmd(DMA1_Channel4, ENABLE);   
        }

你的"0123456012"数据是不是你转换的，因为PC发送"123456"的话，应该手册hex的 31 32 33 34 35 36，即使转换也不应该有‘0,’，另外使用了DMA的话，如果能已知接收到的数据长度，建议使用DMA接收中断，高效且不易出错...

謝謝您的建議！