本例程只能接受发送定长数据，小于或大于规定的数据长度，程序均会工作异常。

1 RX\TD的DMA初始化

void UART2_DMA_TX_Init(void)
{
    DMA_InitTypeDef  DMA_InitStructure;
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);  //ʹÄÜDMA´«Êä
    DMA_DeInit(DMA1_Channel4);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & (UART2->TDR); //UART2_DMA_TXÊý¾Ý¼Ä´æÆ÷
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)txdata; //UART2_DMA_TXµÄÊý¾Ý´æ·Å»ùµØÖ·
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;//Êý¾Ý´Ómemoryµ½ÍâÉè
    DMA_InitStructure.DMA_BufferSize = 1;//UART2_DMA_TXÊý¾Ý¸öÊý
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
    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_VeryHigh;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel4, &DMA_InitStructure);//SPI2 RXΪDMAͨµÀ4
}
void UART2_DMA_RX_Init()
{
    DMA_InitTypeDef  DMA_InitStructure;
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);  //ʹÄÜDMA´«Êä
    DMA_DeInit(DMA1_Channel5);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t) & (UART2->RDR); //UART2_DMA_RXÊý¾Ý¼Ä´æÆ÷
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)rxdata;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//Êý¾Ý´ÓÍâÉèµ½memory
    DMA_InitStructure.DMA_BufferSize = 1;//UART2_DMA_RXÊý¾Ý¸öÊý
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//ÍâÉèµØÖ·²»¸Ä±ä
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;//memoryµØÖ·µÝÔö¿ªÆô
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;//ÆÕͨģʽ
    DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel5, &DMA_InitStructure);//
}

2 main主程序流程

int main(void)
{
    int ret;

    InitSystick();
    delay(10);
    UART2_DMA_TX_Init();
    UART2_DMA_RX_Init();
    Uart_ConfigInit(9600);
    UART_DMACmd(UART2, UART_DMAReq_EN, ENABLE);
    UartSendGroup((u8*)printBuf, sprintf(printBuf, "sprintf ok\r\n"));          //pintf stdio data
    UartSendAscii("UartSendAscii\r\n");                                         //printf string
    UartSendAscii("Please input data ,end with '\\n' \r\n");

    while(1) {
        memset(rxbuf, 0, sizeof(rxbuf));
        ret = UART2ReadbufTimeOut(rxbuf, 10, 100);
        if(ret == UARTSUCESSFUL) {
            UartSendGroup(rxbuf, 10);
        }
    }
}

官方例程的修正已基本完成，需要程序的同学可以到百度网盘下载。
提取码：0o5i