I’m having a problem with uALFAT firmware rev 3.13 and a 16GB micro-SD memory card. My circuit works perfectly every time with a 2GB SD card. When I try a 16GB card I get a non-zero ACK most of the time when I issue the ‘I’ command to mount the card. In these cases the ACK is usually 0x05 (SD timed-out) but is sometimes 0x07 (Failed to send command to SD card). Every now and then it successfully mounts the card.
It seems to me that it takes longer to mount a large SD card, and the uALFAT internal timeout is not long enough in most cases. I believe I have the latest firmware loaded. Is there any way to fix this problem?