请教大家，
/****************************************************************************
Desripton :read block in dma mode
Fuctionname :ReadBlockInDMA()
Input :None
Return :None
*****************************************************************************/
u8 ReadBlockInDMA(u8 *pBuffer, u32 ReadAddr, u16 NumByteToRead)
{
//u32 i = 0;
DMA_InitTypeDef DMA_InitStructure;
u8 rvalue = MSD_RESPONSE_FAILURE;
/* MSD chip select low */
MSD_CS_LOW();
/*initial dma channel 2*/
DMA_DeInit(DMA_Channel2);
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)SPI1_DR_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (u32)pBuffer;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_BufferSize = NumByteToRead;
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_VeryHigh;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA_Channel2, &DMA_InitStructure);
SPI_DMACmd(SPI1, SPI_DMAReq_Rx, ENABLE);
/* Send CMD17 (MSD_READ_SINGLE_BLOCK) to read one block */
MSD_SendCmd(MSD_READ_SINGLE_BLOCK, ReadAddr, 0xFF);
if (!MSD_GetResponse(MSD_RESPONSE_NO_ERROR))
{
/* Now look for the data token to signify the start of the data */
if (!MSD_GetResponse(MSD_START_DATA_SINGLE_BLOCK_READ))
{
DMA_Cmd(DMA_Channel2,ENABLE);
while(!DMA_GetFlagStatus(DMA_FLAG_TC2))
{
}
}
}
/* Get CRC bytes (not really needed by us, but required by MSD) */
MSD_ReadByte();
MSD_ReadByte();
/* Set response value to success */
rvalue = MSD_RESPONSE_NO_ERROR;
DMA_Cmd(DMA_Channel2, DISABLE);
/* MSD chip select high */
MSD_CS_HIGH();
/* Send dummy byte: 8 Clock pulses of delay */
MSD_WriteByte(DUMMY);
/* Returns the reponse */
return rvalue;
}
/******************************************************************************
Description : Write byte in dma mode
Fuctionname : WriteBlockInDMA(u8 *pBuffer,u32 WriteAddr, u16 NumByteToWrite)
Input : pBuffer -- data buffer for send
WriteAddr -- address to write
NumByteToWrite -- data length of the data to write
Output : None
*********************************************************************************/
u8 WriteBlockInDMA(u8 *pBuffer, u32 WriteAddr, u16 NumByteToWrite)
{
//u32 i = 0;
DMA_InitTypeDef DMA_InitStructure;
u8 rvalue = MSD_RESPONSE_FAILURE;
/* MSD chip select low */
MSD_CS_LOW();
/*initial the spi1 in write mode*/
/*initial dma channel 3*/
DMA_DeInit(DMA_Channel3);
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)SPI1_DR_Address;
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(DMA_Channel3, &DMA_InitStructure);
SPI_DMACmd(SPI1, SPI_DMAReq_Tx, ENABLE);
// SPI_Cmd(SPI1, ENABLE);
MSD_SendCmd(MSD_SET_BLOCKLEN,512,0x00);
MSD_ReadByte();
MSD_ReadByte();
/* Send CMD24 (MSD_WRITE_BLOCK) to write multiple block */
MSD_SendCmd(MSD_WRITE_BLOCK, WriteAddr, 0xFF);
/* Check if the MSD acknowledged the write block command: R1 response (0x00: no errors) */
if (!MSD_GetResponse(MSD_RESPONSE_NO_ERROR))
{
/* Send a dummy byte */
MSD_WriteByte(DUMMY);
/* Send the data token to signify the start of the data */
MSD_WriteByte(0xFE);
/* Write the block data to MSD : write count data by block */
DMA_Cmd(DMA_Channel3, ENABLE);
while(!DMA_GetFlagStatus(DMA_FLAG_TC3));
/* Put CRC bytes (not really needed by us, but required by MSD) */
MSD_ReadByte();
MSD_ReadByte();
/* Read data response */
if (MSD_GetDataResponse() == MSD_DATA_OK)
{
rvalue = MSD_RESPONSE_NO_ERROR;
}
}
/* MSD chip select high */
MSD_CS_HIGH();
/* Send dummy byte: 8 Clock pulses of delay */
MSD_WriteByte(DUMMY);
DMA_Cmd(DMA_Channel3, DISABLE);
/* Returns the reponse */
return rvalue;
}
这是分别用dma读写sd卡的读和写一个block的程序，在程序中调用到这俩个程序时，dma读子程序在while(!DMA_GetFlagStatus(DMA_FLAG_TC2)){}这一直等待，也就是说dma传输没有完成。而调用写子程序是完全没问题的，也就是dma时钟等问题以不是问题，不知道还有什么没考虑到的？？？？？
郁闷！！！！！
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