Wiring micro sd card slot to MCU

[hhuyn.1]

I'm drawing schematic for a small project, I have an information trouble with SDIO. I don't know how to wiring SDIO interface to micro sd card slot. Is there any document can help ?

Thank !

Sorry if my English is poor.

[TDK]

Just copy any of the STM32 discovery board schematics. Here is one:

https://www.st.com/resource/en/schematic_pack/stm32429i-eval_sch.zip

[prain]

very simple

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also put a big capacitor for card vdd line

[AElma.1]

Hi, I do not understand one thing. How can you decide value of resistors? I use STM32F446RE so, Can I wire SD card socket (I mean just connection side) directly my microcontrolller with this pull up resistors?

[Tesla DeLorean]

Doing this without pull-up's is probably in-advisable. Typically you just need a relatively weak pull-up, in the 33K or 47K type range, as this would tend to draw less current and require less drive.

If you plan of clocking data at 33 MHz or higher over short distances you might consider 27R or 33R type range series resistor too, to stop ringing/reflections.

The SDIO/SDMMC interface on the F4 has 6 designated pins, typically one would also use a GPIO and a switch on the socket for a card detect mechanism.

Something like this could be directly wired.

https://www.waveshare.com/micro-sd-storage-board.htm

[Nico3]

Do we need external pullup on CLK line ?  

I see there is no pullup on CLK link in STMEval board, but the module by waveshare has.

https://www.waveshare.com/micro-sd-storage-board.htm

[Tesla DeLorean]

It doesn't need one as always an output, but shouldn't be an issue either.

[Nico3]

ok..thanks