DMA_InitTypeDef DMA_InitStructure; 
    
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);//DMA时钟

    DMA_DeInit(DMA1_Channel4);

    DMA_InitStructure.DMA_PeripheralBaseAddr =  (uint32_t) & (ADC1->DR); //外设寄存器基地址
    DMA_InitStructure.DMA_MemoryBaseAddr =(u32)data; //RAM基地址
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; //传输方向
    DMA_InitStructure.DMA_BufferSize = length;//Size
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //外设的地址是否自动增加
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; //RAM的地址是否自动增加

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize =DMA_MemoryDataSize_HalfWord; //传输单位!!!!!!!!

    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//DMA_Mode_Normal; //是否不断传输
    DMA_InitStructure.DMA_Priority = DMA_Priority_Medium; //优先组
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; //是不是RAM2RAM
    DMA_Init(DMA1_Channel4, &DMA_InitStructure); 
    
    DMA_ITConfig(DMA1_Channel5,DMA_IT_TC,ENABLE ); //DMA中断（别忘了NVIC）
    USART_DMACmd(USART1,USART_DMAReq_Tx,ENABLE);//打开外设的DMA连接
　　//　ADC_TempSensorVrefintCmd(ENABLE);//打开内部温度和电压传感器的DMA连接
    DMA_Cmd(DMA1_Channel4,ENABLE);//开启DMA