Question about emmc speed in stm32l4p5g-dk

[fito-jaeuklee]

Hello!

I'm bought new DK board that name STM32L4P5G-DK for testing Fatfs-eMMC example. ( https://github.com/STMicroelectronics/STM32CubeL4/tree/master/Projects/32L4P5GDISCOVERY/Applications/FatFs/FatFs_eMMC_Standalone )

It works fine, but not the speed I expected. Almost datasheet saying that eMMC speed is more than 50MB/s. But real speed is 1MB/s in this example .... :(

I would like to know if there are other ways to improve the speed.

i check up this write/read time

for (counter = 0; counter< N_SIZES; counter++)
{
  if(f_open(&MyFile, "TEST_ACCESS_TIME.TXT", FA_CREATE_ALWAYS | FA_WRITE) == FR_OK)
  {

    /* Start timer counter */
    HAL_TIM_Base_Start(&htim);
    /* Write data to the text file */
     res = f_write(&MyFile, copy_start, data_sizes[counter], (void *)&byteswritten);
    /* Stop timer counter */
    HAL_TIM_Base_Stop(&htim);
    Access_time_us = __HAL_TIM_GET_COUNTER(&htim);
    print_spend_time_clock_write = Access_time_us /= SystemClock;
    read_bytes = byteswritten;
    __HAL_TIM_SET_COUNTER(&htim, 0x0);

    if((byteswritten > 0) && (res == FR_OK))
    {
      /* Close the open text file */
      f_close(&MyFile);

      /* Open the text file object with read access */
      if(f_open(&MyFile, "TEST_ACCESS_TIME.TXT", FA_READ) == FR_OK)
      {
        /* Start timer counter */
        HAL_TIM_Base_Start(&htim);
        /* Read data from the text file */
        res = f_read(&MyFile, copy_start, data_sizes[counter], (void *)&bytesread);
        /* Stop timer counter */
        HAL_TIM_Base_Stop(&htim);
        Access_time_us = __HAL_TIM_GET_COUNTER(&htim);
        print_spend_time_clock_read = Access_time_us /= SystemClock;
        read_bytes = byteswritten;
        __HAL_TIM_SET_COUNTER(&htim, 0x0);

        if((bytesread > 0) && (res == FR_OK))
        {
          /* Close the open text file */
          f_close(&MyFile);

          /* Compare read data with the expected data */
          if((bytesread != byteswritten))
          {
            Error_Handler();
          }
        }
      }
    }
  }

[fito-jaeuklee]

This capture is Stm32l4p5g-dk built-in chip emmc data speed from datasheet.

[RKOUSTM]

Hi @fito-jaeuklee,

Thank you for your contribution. To improve the eMMC speed, you can call BSP_MMC_ConfigSpeedBusOperation () in your application just inside function MMC_initialize() as follows:

DSTATUS MMC_initialize(BYTE lun)
{

    if (MMC_OK == BSP_MMC_DeInit())
    {
      if (MMC_OK == BSP_MMC_Init())
      {
+       BSP_MMC_ConfigSpeedBusOperation(SDMMC_SPEED_MODE_HIGH);
        Stat = MMC_CheckStatus(lun);
      }
    }

   return Stat;
}

Please let us know your feedback so that we can help you.

With regards,