最近在用STM32F103Vet6+STemwin做一个拼音输入法的项目,所以字库必须放到TF卡上,所以必使用到SD卡驱动,因为同时要使用USB访问SD卡,所以SD卡必须保证在最佳性能状态,在网上找了几种驱动测试,都出现卡死现像,包括原子哥的驱动同出现问题．还试了中断模式和查询模式，只有查询模式效果最好，但是要把SD卡的工作频率降到10M以下才能工作正常.就将就用查询模式吧,就在昨晚又开始死机了,没办法了,但是总不能放弃项目吧,只好分析代码了,再静下来想一想,SD的工作频率24M,CPU的频率才72M,在4位模式下那CPU起不是要在10个周期(72242+开销)内处理完SD卡的传送？立该用printf在SD_Read上把结果打印出来,结果返回RXOVRRUN，明显了，就是CPU取数速度跟不上SDIO。好，问题找到了，就开始修改
DRESULT disk_read (
BYTE drv, /* Physical drive nmuber (0..) */
BYTE *buff, /* Data buffer to store read data */
DWORD sector, /* Sector address (LBA) */
BYTE count /* Number of sectors to read (1..255) */
)
{
BYTE i;
SD_Error Status; 

if (!count) return RES_PARERR;  //count????????0??·??ò·????????í?ó

if(drv==0)
{
//int i;
//Status = SD_ReadDisk(buff,sector,count);
/*for(i=0;i<512;i++)
{
Debug("0x%02x ",*(buff+i));
}

Debug(" ");*/
  /*switch(SD_Mode)
  {
  case 0:  //dma·???
      if(count==1)// 1??sector??????×÷      
      { */ 
for(i = 0; i < count; i++)    
 {  
Status = SD_ReadBlock((sector + i) << 9,(u32 *)(&buff[i<<9]),BlockSize);
//Debug("Read:%d ",Status);
}
      /* }                                                
      else                        
      {    
      Status = SD_ReadMultiBlocks(sector << 9,(u32 *)(&buff[0]),BlockSize,count);                                      
      }
    break;
   
  case 1:  
DISABLE_INT();
      if(count==1)                  
      {      
    Status = SD_ReadBlock(sector<<9,(u32 *)(&buff[0]),BlockSize);                                              
      }                                                
      else                        
      {    
      Status = SD_ReadMultiBlocks(sector<<9 ,(u32 *)(&buff[0]),BlockSize,count);                                     
      }

ENABLE_INT();*/
      /* break;
     
    default:
    Status=SD_ERROR;
}*/

   
   if(Status == SD_OK)
       return RES_OK;
   else
       return RES_ERROR;
}
else//???§??????0????×÷
    {
return RES_ERROR;  
    }
}
从上面代码可以看到我把MutilReadBlock屏蔽了，为什么要屏蔽呢？我们来分析一吓，因为DMA SIZE只有512字节，如果我们用MutilReadBlock来读SD卡的话,由于CPU速度问题，CPU没有把512字节取完，SDIO就会继续向DMA里传数据，这里如果DMA满了，就会产生RXOVRRUN。改了以上代码测试，结果返回OK了，但是STemwin的界面还是没有正确，在这里估计是掉数据了，于是再分析ReadBlock方法

SD_Error SD_ReadBlock(uint32_t addr, uint32_t *readbuff, uint16_t BlockSize)
{
  SD_Error errorstatus = SD_OK;
  uint32_t count = 0, *tempbuff = readbuff;
  uint8_t power = 0;

  if (NULL == readbuff)
  {
    errorstatus = SD_INVALID_PARAMETER;
    return(errorstatus);
  }

  TransferError = SD_OK;
  TransferEnd = 0;
  TotalNumberOfBytes = 0;

  /* Clear all DPSM configuration */
  SDIO_DataInitStructure.SDIO_DataTimeOut = SD_DATATIMEOUT;
  SDIO_DataInitStructure.SDIO_DataLength = 0;
  SDIO_DataInitStructure.SDIO_DataBlockSize = SDIO_DataBlockSize_1b;
  SDIO_DataInitStructure.SDIO_TransferDir = SDIO_TransferDir_ToCard;
  SDIO_DataInitStructure.SDIO_TransferMode = SDIO_TransferMode_Block;
  SDIO_DataInitStructure.SDIO_DPSM = SDIO_DPSM_Disable;
  SDIO_DataConfig(&SDIO_DataInitStructure);
  SDIO_DMACmd(DISABLE);

  if (SDIO_GetResponse(SDIO_RESP1) & SD_CARD_LOCKED)
  {
    errorstatus = SD_LOCK_UNLOCK_FAILED;
    return(errorstatus);
  }
  
  if (CardType == SDIO_HIGH_CAPACITY_SD_CARD)
  {
    BlockSize = 512;
    addr /= 512;
  }
  if ((BlockSize > 0) && (BlockSize <= 2048) && ((BlockSize & (BlockSize - 1)) == 0))
  {
    power = convert_from_bytes_to_power_of_two(BlockSize);

    /* Set Block Size for Card */
    SDIO_CmdInitStructure.SDIO_Argument = (uint32_t) BlockSize;
    SDIO_CmdInitStructure.SDIO_CmdIndex = SDIO_SET_BLOCKLEN;
    SDIO_CmdInitStructure.SDIO_Response = SDIO_Response_Short;
    SDIO_CmdInitStructure.SDIO_Wait = SDIO_Wait_No;
    SDIO_CmdInitStructure.SDIO_CPSM = SDIO_CPSM_Enable;
    SDIO_SendCommand(&SDIO_CmdInitStructure);

    errorstatus = CmdResp1Error(SDIO_SET_BLOCKLEN);

    if (SD_OK != errorstatus)
    {
      return(errorstatus);
    }
  }
  else
  {
    errorstatus = SD_INVALID_PARAMETER;
    return(errorstatus);
  }

if(DeviceMode == SD_INTERRUPT_MODE)
{
SDIO_ITConfig(SDIO_IT_DCRCFAIL | SDIO_IT_DTIMEOUT | SDIO_IT_DATAEND | SDIO_IT_RXOVERR | SDIO_IT_RXFIFOHF | SDIO_IT_STBITERR, ENABLE);
}
else if(DeviceMode == SD_DMA_MODE)
{
SDIO_ITConfig(SDIO_IT_DCRCFAIL | SDIO_IT_DTIMEOUT | SDIO_IT_DATAEND | SDIO_IT_RXOVERR | SDIO_IT_STBITERR, ENABLE);
SDIO_DMACmd(ENABLE);
DMA_RxConfiguration(readbuff, BlockSize);
}     //DMA配置代码和中断使能代码放这里

  SDIO_DataInitStructure.SDIO_DataTimeOut = SD_DATATIMEOUT;
  SDIO_DataInitStructure.SDIO_DataLength = BlockSize;
  SDIO_DataInitStructure.SDIO_DataBlockSize = (uint32_t) power << 4;
  SDIO_DataInitStructure.SDIO_TransferDir = SDIO_TransferDir_ToSDIO;
  SDIO_DataInitStructure.SDIO_TransferMode = SDIO_TransferMode_Block;
  SDIO_DataInitStructure.SDIO_DPSM = SDIO_DPSM_Enable;
  SDIO_DataConfig(&SDIO_DataInitStructure);

  TotalNumberOfBytes = BlockSize;
  StopCondition = 0;
  DestBuffer = readbuff;

  /* Send CMD17 READ_SINGLE_BLOCK */
  SDIO_CmdInitStructure.SDIO_Argument = (uint32_t)addr;
  SDIO_CmdInitStructure.SDIO_CmdIndex = SDIO_READ_SINGLE_BLOCK;
  SDIO_CmdInitStructure.SDIO_Response = SDIO_Response_Short;
  SDIO_CmdInitStructure.SDIO_Wait = SDIO_Wait_No;
  //SDIO_CmdInitStructure.SDIO_Wait = SDIO_Wait_Pend;
  SDIO_CmdInitStructure.SDIO_CPSM = SDIO_CPSM_Enable;
  SDIO_SendCommand(&SDIO_CmdInitStructure);

  errorstatus = CmdResp1Error(SDIO_READ_SINGLE_BLOCK);

  if (errorstatus != SD_OK)
  {
    return(errorstatus);
  }
  /* In case of single block transfer, no need of stop transfer at all.*/
  if (DeviceMode == SD_POLLING_MODE)
  {
    /* Polling mode */
 

    while (!(SDIO->STA &(SDIO_FLAG_RXOVERR | SDIO_FLAG_DCRCFAIL | SDIO_FLAG_DTIMEOUT | SDIO_FLAG_DBCKEND | SDIO_FLAG_STBITERR)))
    {
      if (SDIO_GetFlagStatus(SDIO_FLAG_RXFIFOHF) != RESET)
      {
        for (count = 0; count < 8; count++)
        {
          *(tempbuff + count) = SDIO_ReadData();
        }
        tempbuff += 8;
      }
    }

    if (SDIO_GetFlagStatus(SDIO_FLAG_DTIMEOUT) != RESET)
    {
      SDIO_ClearFlag(SDIO_FLAG_DTIMEOUT);
      errorstatus = SD_DATA_TIMEOUT;
      return(errorstatus);
    }
    else if (SDIO_GetFlagStatus(SDIO_FLAG_DCRCFAIL) != RESET)
    {
      SDIO_ClearFlag(SDIO_FLAG_DCRCFAIL);
      errorstatus = SD_DATA_CRC_FAIL;
      return(errorstatus);
    }
    else if (SDIO_GetFlagStatus(SDIO_FLAG_RXOVERR) != RESET)
    {
      SDIO_ClearFlag(SDIO_FLAG_RXOVERR);
      errorstatus = SD_RX_OVERRUN;
      return(errorstatus);
    }
    else if (SDIO_GetFlagStatus(SDIO_FLAG_STBITERR) != RESET)
    {
      SDIO_ClearFlag(SDIO_FLAG_STBITERR);
      errorstatus = SD_START_BIT_ERR;
      return(errorstatus);
    }
    while (SDIO_GetFlagStatus(SDIO_FLAG_RXDAVL) != RESET)
    {
      *tempbuff = SDIO_ReadData();
      tempbuff++;
    }

    /* Clear all the static flags */
    SDIO_ClearFlag(SDIO_STATIC_FLAGS);
  }
  else if (DeviceMode == SD_INTERRUPT_MODE)
  {
    
    while ((TransferEnd == 0) && (TransferError == SD_OK))
    {}
    if (TransferError != SD_OK)
    {
      return(TransferError);
    }
  }
  else if (DeviceMode == SD_DMA_MODE)
  {
    //这里原来放DMA配置和中断使能代码
    while (DMA_GetFlagStatus(DMA2_FLAG_TC4) == RESET)
    {}
  }
  return(errorstatus);
}

分析上面代码，发现官方源码是在SDIO开始传送后，DMA才配置，这样做，在高速的CPU上可能没问题，但在103上肯定掉数据，于上就修改成上面的方式，改好后，STemwin终于正常了，至此SD驱动应该完美解决卡死问题