SDcard->emmc with STM32F205

岡田伸一 · ‎2025-09-23

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?

Tesla DeLorean · ‎2025-09-23

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

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FBL · ‎2025-09-24

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.

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Saket_Om · ‎2025-09-24

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.

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Saket_Om