SDIO卡上电识别，为什么要循环发送ACMD41？

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楼主

车水马龙|

楼主 | 2019-11-28 14:58 | 只看该作者回帖奖励

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ACM, sd, IO, ST, ni

详见《零死角玩转STM32-V2.pdf》的399页，如下
while ((!validvoltage) && (count < SD_MAX_VOLT_TRIAL))
{
   SDIO_CmdInitStructure.SDIO_Argument = 0x00;
   SDIO_CmdInitStructure.SDIO_CmdIndex = SD_CMD_APP_CMD;
   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_APP_CMD);

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

   SDIO_CmdInitStructure.SDIO_Argument = SD_VOLTAGE_WINDOW_SD | SDType;
   SDIO_CmdInitStructure.SDIO_CmdIndex = SD_CMD_SD_APP_OP_COND;
   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 = CmdResp3Error();

   if (errorstatus != SD_OK)
   {
      return(errorstatus);
   }
   response = SDIO_GetResponse(SDIO_RESP1);
   validvoltage = (((response >> 31) == 1) ? 1 : 0);
   count++;
}

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