I was very excited to see this thread pop up. I was just about to post the exact same issue. This error has been crippling my system for a while now, and I’ve done exhaustive testing of different SD cards, formatting, FEZ software, even replacing a resistor as suggested in a previous thread (essentially adding a 4.7k R in parallel with R14–a pull down at SD power). None of that, save the recommended FAT format, seemed to do much of anything in the long run.
The most frustrating part of this situation is that I’ve been seeing this failure not immediately, but after various amounts of time between 1 second and nearly 2 hours into my data logging application. Even with Verbatim cards, I was consistently failing around 7 minutes into my execution. For the record, all I’m doing is simple USB Host->SD card writes of not more than a few hundred bytes of data/sec.
I will happily try this second HW mod, though I’m still uneasy, since the Verbatims I got to replace the Kingstons are also failing. I’ve been posting about this a bit on the main GHI USBizi forum, and they said NETMF 4.1 has many fixes for the FAT filesystem. It should be out within a week or two.
I caution those who think the problem is solved by moving to a different SD card. Not to rain on any parades, but I assumed the Verbatims were better when they lasted longer than the ~45 seconds of the Kingston (pre-R14 mod), but on further inspection I’m still getting this CLR_E_FILE_IO exception. Let’s hope the cap change will help.