SDIO works well in SD-1bit mode but not in SD 4bit mode

[Yang Yang]

I am using cubemx generated SD card test code on a custom board. And everything looks fine in SD 1bit mode, I can create new file, read and write data to it correctly. But when I am using 4bit mode, the f_open() function stalls. What might be the problem?

[Imen.D]

Hello @Yang Yang​ ,

Which device are you using ?

Kind Regards,

Imen

[Tesla DeLorean]

Might not be wired properly, ie mixed bits, too long, no pull-ups, etc.

4-bit mode sensitive to relative bit skewing

Not much to work with, engineering shouldn't need to be a guessing game. Present a more complete context for your problem.

[Yang Yang]

Hi, Clive

STM32F415RGT6 MCU is used. And I am quite sure the connections between MCU and microSD card is correct. So I think we can focus on the software side.

Best Regards

Yang