Question
SD card initialization problem in HAL driver function SD_FindSCR
Hello,
sometimes the initialization of the SD card fails in function SD_FindSCR.
There seems to be a timing problem between SDMMC_ConfigData and SDMMC_CmdSendSCR because send data starts before SDMMC is ready.
With an additional wait function for status bits it works for me (see code below).
I can't find an exact timing specification between SDMMC process steps (waiting for status bits or time) in hardware documentation (STM32F777).
But it seems that there are some actions required to improve the reliabilty of the SDMMC HAL driver functions in STM32F7xx_HAL_SD.C
static uint32_t SD_FindSCR(SD_HandleTypeDef *hsd, uint32_t *pSCR)
{
SDMMC_DataInitTypeDef config;
uint32_t errorstate;
uint32_t tickstart = HAL_GetTick();
uint32_t index = 0U;
uint32_t tempscr[2U] = {0U, 0U};
uint32_t *scr = pSCR;
/* Set Block Size To 8 Bytes */
errorstate = SDMMC_CmdBlockLength(hsd->Instance, 8U);
if(errorstate != HAL_SD_ERROR_NONE)
{
return errorstate;
}
/* Send CMD55 APP_CMD with argument as card's RCA */
errorstate = SDMMC_CmdAppCommand(hsd->Instance, (uint32_t)((hsd->SdCard.RelCardAdd) << 16U));
if(errorstate != HAL_SD_ERROR_NONE)
{
return errorstate;
}
config.DataTimeOut = SDMMC_DATATIMEOUT;
config.DataLength = 8U;
config.DataBlockSize = SDMMC_DATABLOCK_SIZE_8B;
config.TransferDir = SDMMC_TRANSFER_DIR_TO_SDMMC;
config.TransferMode = SDMMC_TRANSFER_MODE_BLOCK;
config.DPSM = SDMMC_DPSM_ENABLE;
(void)SDMMC_ConfigData(hsd->Instance, &config);
//////////////////////////////////////////////////////////////////////////////
// STA register is 0x00000000 immediately after configuration -> not ready yet
while(!__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXACT))
{
if((HAL_GetTick() - tickstart) >= SDMMC_DATATIMEOUT)
{
return HAL_SD_ERROR_TIMEOUT;
}
}
// STA register is 0x00082000 now -> ready to receive data
// (Bit 13 RXACT: Data receive in progress)
// (Bit 19 RXFIFOE: Receive FIFO empty)
// it takes 32 system clock periods (system clock 216Mhz)
//////////////////////////////////////////////////////////////////////////////
/* Send ACMD51 SD_APP_SEND_SCR with argument as 0 */
errorstate = SDMMC_CmdSendSCR(hsd->Instance);
if(errorstate != HAL_SD_ERROR_NONE)
{
return errorstate;
}
while(!__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXOVERR | SDMMC_FLAG_DCRCFAIL | SDMMC_FLAG_DTIMEOUT | SDMMC_FLAG_DBCKEND))
{
if(__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXDAVL))
{
*(tempscr + index) = SDMMC_ReadFIFO(hsd->Instance);
index++;
}
if((HAL_GetTick() - tickstart) >= SDMMC_DATATIMEOUT)
{
return HAL_SD_ERROR_TIMEOUT;
}
}
if(__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_DTIMEOUT))
{
__HAL_SD_CLEAR_FLAG(hsd, SDMMC_FLAG_DTIMEOUT);
return HAL_SD_ERROR_DATA_TIMEOUT;
}
else if(__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_DCRCFAIL))
{
__HAL_SD_CLEAR_FLAG(hsd, SDMMC_FLAG_DCRCFAIL);
return HAL_SD_ERROR_DATA_CRC_FAIL;
}
else if(__HAL_SD_GET_FLAG(hsd, SDMMC_FLAG_RXOVERR))
{
__HAL_SD_CLEAR_FLAG(hsd, SDMMC_FLAG_RXOVERR);
return HAL_SD_ERROR_RX_OVERRUN;
}
else
{
/* No error flag set */
/* Clear all the static flags */
__HAL_SD_CLEAR_FLAG(hsd, SDMMC_STATIC_DATA_FLAGS);
*scr = (((tempscr[1] & SDMMC_0TO7BITS) << 24) | ((tempscr[1] & SDMMC_8TO15BITS) << 8) |\
((tempscr[1] & SDMMC_16TO23BITS) >> 8) | ((tempscr[1] & SDMMC_24TO31BITS) >> 24));
scr++;
*scr = (((tempscr[0] & SDMMC_0TO7BITS) << 24) | ((tempscr[0] & SDMMC_8TO15BITS) << 8) |\
((tempscr[0] & SDMMC_16TO23BITS) >> 8) | ((tempscr[0] & SDMMC_24TO31BITS) >> 24));
}
return HAL_SD_ERROR_NONE;
}