I was experimenting with the local filesystem and now my mbed no longer apperas in windows explorer as mbed but is no a j drive. If I try to format this j drive it says no disk present. Where has mbed gone ? Its still running the last program I loaded, reading the analog port, but now I cant contact it at all. Have restarted pc, checked serial ports etc.Can see the results of current program updating in TeraTerm. Is there any way to do a factory reset ?

I found that first updating the firmware and then removing all files restored the mbed. If iI pressed the reset button and kept it pressed I could see the mbed long enough to drag the firmware onto it.

Hi Gregory,

What you experienced is expected behavior, see:

http://mbed.org/handbook/LocalFileSystem

When your program opens a file using the LocalFileSystem, control of the disk is taken away from the PC, so it disappears, or is marked as "removed". This is much like a digital camera which can either be a disk drive, or a digital camera, but not both at the same time.

If your program opens a file as soon as it starts, your PC will never see the flash drive. In your case, no firmware update was necessary. Holding down the button held the microcontroller in reset, your program wasn't run, so a file wasn't opened, so the disk wasn't taken away from your PC. When you removed all your programs from the mbed disk, there was no longer a program running LocalFileSystem, so it didn't get taken away from the PC.

I hope this clarifies.

All the best, Chris