用SPI的DMA方式写flash问题

void SPI_FLASH_DMA_PageWrite(u8 *pBuffer, u32 WriteAddr, u16 NumByteToWrite)

{

    //u32 i = 0;

    DMA_InitTypeDef  DMA_InitStructure;

    /* MSD chip select low */

    SPI_FLASH_CS_LOW();



    /*initial the spi1 in write mode*/

    /*initial dma channel5*/

    DMA_DeInit(DMA1_Channel5);

    DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)SPI2->DR;

    DMA_InitStructure.DMA_MemoryBaseAddr = (u32)pBuffer;

    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;

    DMA_InitStructure.DMA_BufferSize = NumByteToWrite;

    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_Channel5, &DMA_InitStructure);

    SPI_I2S_DMACmd(SPI2, SPI_I2S_DMAReq_Tx, ENABLE);

   // SPI_Cmd(SPI1, ENABLE);

   SPI_FLASH_WriteEnable();



    SPI_FLASH_CS_LOW();

  /* Send "Write to Memory " instruction */

    SPI_FLASH_SendByte(WRITE);

  /* Send WriteAddr high nibble address byte to write to */

    SPI_FLASH_SendByte((WriteAddr & 0xFF0000) >> 16);

  /* Send WriteAddr medium nibble address byte to write to */

    SPI_FLASH_SendByte((WriteAddr & 0xFF00) >> 8);

  /* Send WriteAddr low nibble address byte to write to */

    SPI_FLASH_SendByte(WriteAddr & 0xFF);



    DMA_Cmd(DMA1_Channel5, ENABLE);



    while(!DMA_GetFlagStatus(DMA1_FLAG_TC4)) ;

                

        DMA_Cmd(DMA1_Channel5, DISABLE);

    /* MSD chip select high */

    SPI_FLASH_CS_HIGH();



    /* Send dummy byte: 8 Clock pulses of delay */

    SPI_FLASH_SendByte(0xA5);

}

为什么不行呢，一直死到这个里面while(!DMA_GetFlagStatus(DMA1_FLAG_TC4)) ;