学习这里首先要了解一下SD卡基本资料：
SD卡的协议部分太多，也比较复杂，建议资料：《Simplified_Physical_Layer_Spec.pdf》其主要复杂在繁多的命令，一共有64个命令，各个命令代表什么可查资料。
关于这里大部分都是熟悉函数然后直接调用库就行，但还是需要每个函数都去读一下的，后面会有具体函数的使用实例，到时候再补充。
我们代码中一般用到的是ARM官方给的SD卡的库，但是库中存在问题,SD_Error SD_ReadBlock()缺少代码：(有标注，可直接替换)
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; //传输结束标置位，在中断服务置1 StopCondition = 0; //怎么用的？ SDIO->DCTRL = 0x0; if (CardType == SDIO_HIGH_CAPACITY_SD_CARD) { BlockSize = 512; ReadAddr /= 512; } /*******************add，没有这一段容易卡死在DMA检测中*************************************/ /* Set Block Size for Card，cmd16, * 若是sdsc卡，可以用来设置块大小， * 若是sdhc卡，块大小为512字节，不受cmd16影响 */ 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); }文章来源: STM32笔记--SDIO(SD卡读取)