usb使用DMA进行数据通信

tergar_daniel · 发表于 2012-11-22 20:03:49

我使用STM32与SPIFLASH做了一个U盘，使用SPI通信都能很正常的工作，但速度不快最多只能达到30KBPS。后来是同DMA-SPI速度是上去了,也能读写，但就是格式化不了，一下两段代码分别是SPI通信与DMA-SPA通信，请教是哪边出了问题。
SPI：
void W25X_Write_Bytes(uint32_t nSector,u8* pBuffer, u16 nBytes)
{
u16 i;
uint32_t k1;
for(i=0;i<nBytes;i++)
{
  W25X_Write_Enable();
  FLASH_CS_0();
  SPI_Write_Byte(W25X_PageProgram);
  SPI_Write_Byte((u8)(((nSector+i) & 0xFFFFFF) >> 16)); /* 发送3个字节的地址信息 */
  SPI_Write_Byte((u8)(((nSector+i) & 0xFFFF) >> 8));
  SPI_Write_Byte((u8)(nSector+i) & 0xFF);
  k1=nSector+i;

// for(i=0;i<nBytes;i++)
  SPI_Write_Byte(pBuffer);

  FLASH_CS_1();

  W25X_Wait_Busy();
}
}

DMA_SPI:

#define DMA_BUFFER_SIZE           128
static uint8_t _spi_flash_buffer[ DMA_BUFFER_SIZE ];void W25X_Write_Bytes(uint32_t nSector,u8* pBuffer, u16 nBytes)
{
u16 i;
uint32_t k1,k2,k3;
for(i=0; i<nBytes/DMA_BUFFER_SIZE; i++)
{
  W25X_Write_Enable();
  FLASH_CS_0();
  SPI_Write_Byte(W25X_PageProgram);
  k1=nSector+i*DMA_BUFFER_SIZE;
  SPI_Write_Byte((u8)((nSector+i*DMA_BUFFER_SIZE) & 0xFFFFFF >> 16)); /* 发送3个字节的地址信息 */
  k2=nSector+i*DMA_BUFFER_SIZE;
  SPI_Write_Byte((u8)((nSector+i*DMA_BUFFER_SIZE) & 0xFFFF >> 8));
  k3=nSector+i*DMA_BUFFER_SIZE;
  SPI_Write_Byte((u8)((nSector+i*DMA_BUFFER_SIZE) & 0xFF) );

  memcpy(_spi_flash_buffer,pBuffer+i*DMA_BUFFER_SIZE,DMA_BUFFER_SIZE);
  DMA_Txconfig((uint32_t )_spi_flash_buffer, DMA_BUFFER_SIZE);
  DMA_Cmd(DMA1_Channel5, ENABLE);
  DMA_Cmd(DMA1_Channel4, ENABLE);
        while (!(DMA_GetFlagStatus(DMA1_FLAG_TC5)));
        SPI_I2S_DMACmd(SPI2, SPI_I2S_DMAReq_Tx|SPI_I2S_DMAReq_Rx , DISABLE);
}
FLASH_CS_1();
W25X_Wait_Busy();
}
其中DMA_Txconfig((uint32_t )_spi_flash_buffer, DMA_BUFFER_SIZE) 是对DMA进行配置