SDIO works in 1 bit mode but 4 bit mode not

[SEMad]

Hi.

I use a STM32F207VCT6 custom board, and i'm sure the connections are corrrect.

in 1 bit mode everythings is OK and i can read and write on micro sd.

but in 4 bit mode micro sd will mount but other functions won't work! its a little bit weird!!

i increased the sdio clock prescaler to 4... but same result...

[Tesla DeLorean]

Very sensitive to signal skewing, cross-talk, line-lengths, stubs and termination.

The EVAL series boards have viable schematics.

[Tesla DeLorean]