I'm using Chan's FAT-FS. And I use an SD card by a German manufacturer "NuDisc". This card works perfectly fine in my Linux distro and works fine with f_mount, f_read, f_write (I tested it by creating a file, writing it, and reading to see if the written data was actually written). But when I used f_mkfs I receive an FR_DISK_ERR. This is because the getCardInfo (line 223, user_diskio.c) returns 0 after a time out. We send CMD9 and wait to receive 0xFE which we never get, so timeout.
*Why is this card not responding to CMD9?
*How was the Linux OS able to format this SD card if CMD9 does not respond? Is the OS waiting for a longer time?