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DrPi
Associate
August 24, 2025
Solved

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

  • August 24, 2025
  • 2 replies
  • 634 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

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

KDJEM.1
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

 

To give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
DrPi
DrPiAuthor
Associate
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.3
AScha.3Best answer
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.

"If you feel a post has answered your question, please click ""Accept as Solution""."
DrPi
DrPiAuthor
Associate
August 30, 2025

You are right. I missed this information.

Thanks for pointing me on it.