How could I use the 4-bit width SD Card with FATFS on F746-Disco

[Lingjun Kong]

Posted on July 17, 2017 at 22:28

at the thread: 

https://community.st.com/0D50X00009XkXXqSAN

I set the sd card as 4-bit width as mentioned on that thread. but cannot mount the sd card.

doe.john.016

 suggest me use 1-bit width and the system could work well.

so my question is, why it couldn't work when I config the width as 4bit? how should I use the 4-bit sdio on F746?

[Tesla DeLorean]

Posted on July 18, 2017 at 00:03

You typically negotiate initial contact at low speed 1-bit, and then move to higher speeds and/or 4-bit if the card supports it by sending a command to the card, and switching modes on the SDIO controller side.

[Lingjun Kong]

Posted on August 03, 2017 at 20:45

Thanks, that make me sense.