STM32 Notes--SDIO (SD card reading)

To learn here, you must first understand the basic information of SD card:

The SD card protocol has too many parts and is quite complicated. The recommended document is: "Simplified_Physical_Layer_Spec.pdf". Its main complexity lies in the numerous commands. There are 64 commands in total. You can check the document for what each command represents.

Most of the time here you just need to be familiar with the functions and call the library directly, but you still need to read each function. There will be examples of the use of specific functions later, which will be supplemented at that time.

The SD card library provided by ARM is generally used in our code, but there is a problem in the library, SD_Error SD_ReadBlock() is missing code: (marked, can be directly replaced)

SD_Error SD_ReadBlock(uint8_t *readbuff, uint32_t ReadAddr, uint16_t BlockSize)

{

  SD_Error errorstatus = SD_OK;

#if defined (SD_POLLING_MODE) 

  uint32_t count = 0, *tempbuff = (uint32_t *)readbuff;

#endif

  TransferError = SD_OK;

  TransferEnd = 0; //Set the transfer end flag, set to 1 in the interrupt service

  StopCondition = 0; //How to use it?

  SDIO->DCTRL = 0x0;

  if (CardType == SDIO_HIGH_CAPACITY_SD_CARD)

  {

    BlockSize = 512;

    ReadAddr /= 512;

  }

  /*******************add, without this section, it is easy to get stuck in DMA detection****************************************/

  /* Set Block Size for Card，cmd16,

* If it is a sdsc card, it can be used to set the block size.

* If it is an SDHC card, the block size is 512 bytes and is not affected by cmd16 

*/

  SDIO_CmdInitStructure.SDIO_Argument = (uint32_t) BlockSize;

  SDIO_CmdInitStructure.SDIO_CmdIndex = SD_CMD_SET_BLOCKLEN;

  SDIO_CmdInitStructure.SDIO_Response = SDIO_Response_Short;   //r1

  SDIO_CmdInitStructure.SDIO_Wait = SDIO_Wait_No;

  SDIO_CmdInitStructure.SDIO_CPSM = SDIO_CPSM_Enable;

  SDIO_SendCommand(&SDIO_CmdInitStructure);

  errorstatus = CmdResp1Error(SD_CMD_SET_BLOCKLEN);

  if (SD_OK != errorstatus)

  {

    return(errorstatus);

  }

 /*********************************************************************************/

  SDIO_DataInitStructure.SDIO_DataTimeOut = SD_DATATIMEOUT;

  SDIO_DataInitStructure.SDIO_DataLength = BlockSize;

  SDIO_DataInitStructure.SDIO_DataBlockSize = (uint32_t) 9 << 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);

  /*!< Send CMD17 READ_SINGLE_BLOCK */

  SDIO_CmdInitStructure.SDIO_Argument = (uint32_t)ReadAddr;

  SDIO_CmdInitStructure.SDIO_CmdIndex = SD_CMD_READ_SINGLE_BLOCK;

  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(SD_CMD_READ_SINGLE_BLOCK);

  if (errorstatus != SD_OK)

  {

    return(errorstatus);

  }

#if defined (SD_POLLING_MODE)  

  /*!< In case of single block transfer, no need of stop transfer at all.*/

  /*!< 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);

#elif defined (SD_DMA_MODE)

    SDIO_ITConfig(SDIO_IT_DATAEND, ENABLE);

    SDIO_DMACmd(ENABLE);

    SD_DMA_RxConfig((uint32_t *)readbuff, BlockSize);

#endif

  return(errorstatus);

}