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Visitor II
August 24, 2025
Solved

Is there a reference design to connect a STM32U535 to a SDHC interface ?

  • August 24, 2025
  • 2 replies
  • 633 views

Hi,

I'm working on a design containing a STM32U535. I need to connect it to a SDHC interface (µSDHC connector). 

The STM32U5 documentation talks about a SDMMC1_CKIN signal. It is not clear to me if this signal is always required or not. I think the documentation is not clear on this.

I do not use external transceiver and I don't need UHS-1 speed (1.8V mode).

Is there a reference design with a STM32U5 and a (µ)SDHC connector ? I have not been able to find one.

Nicolas

    This topic has been closed for replies.
    Best answer by AScha.3

    Hi,

    >I do not use external transceiver

    so rm says :

    AScha3_0-1756239836915.png

    -> no need or chance to connect ckin to anything useful.

    and a sd-card has these pins to connect :

    AScha3_1-1756240006022.png

    >if this signal is always required or not

    So obviously not required.

    2 replies

    Technical Moderator
    August 26, 2025

    Hello @DrPi and welcome to the community;

     

    The STM32L476G-EVAL board have a slot for microSD™ card supporting SD, SDHC, SDXC.

    I recommend you referring to the board schematic and get inspired to design your PCB. 

    KDJEM1_0-1756204864177.png

     

    I hope this help you.

    Thank you.

    Kaouthar

     

    DrPiAuthor
    Visitor II
    August 26, 2025

    Hello @KDJEM.1 ,

    Thanks for your answer. Unfortunately, the design you reference is of no help with my problem. The µController (STM32L476G) used on this design does not have a SDMMC1_CKIN pin. So I can't deduce anything concerning the usage of the STM32L476ZGT6U signal.

     

    Regards,

    Nicolas

    AScha.3Answer
    Super User
    August 26, 2025

    Hi,

    >I do not use external transceiver

    so rm says :

    AScha3_0-1756239836915.png

    -> no need or chance to connect ckin to anything useful.

    and a sd-card has these pins to connect :

    AScha3_1-1756240006022.png

    >if this signal is always required or not

    So obviously not required.

    DrPiAuthor
    Visitor II
    August 30, 2025

    You are right. I missed this information.

    Thanks for pointing me on it.