Skip to main content
岡田伸一
Explorer II
September 24, 2025
Solved

SDcard->emmc with STM32F205

I am using an SD card in SDIO mode with the STM32F205. I am planning to replace the SD card with an eMMC. If the eMMC has SD card mode, can I replace it without changing the program?

This topic has been closed for replies.
Saket_OmBest answer
ST Technical Moderator
September 24, 2025

Hello @岡田伸一 

If the eMMC supports SD card mode and is configured to boot in that mode, it should respond to SD commands just like an SD card.

In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Saket_Om
View in thread

3 replies

Tesla DeLorean
Tesla DeLorean
Guru
September 24, 2025

The MMC has some slightly different initialization commands, and you have to use EXTCSD to determine the block capacity. 

Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..
    FBL
    ST Technical Moderator
    September 24, 2025

    Hi @岡田伸一 

    I suggest you this application note Getting started with the STM32H7 MCU SDMMC host controller to learn about SDMMC controller to be used to interface your external memory.  

    Second, you need to refer to your eMMC specifications to ensure which protocol it supports an to ensure proper initialization. 

    To give better visibility on the answered topics, please click on "Best answer" on the reply which solved your issue or answered your question.Best regards,FBL
      Saket_OmBest answer
      ST Technical Moderator
      September 24, 2025

      Hello @岡田伸一 

      If the eMMC supports SD card mode and is configured to boot in that mode, it should respond to SD commands just like an SD card.

      In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question. Saket_Om
        Terms & ConditionsAccessibility statement