Hi Matthew
It sounds as though your board is resetting (which will cause this behavior). If it is not resetting (eg. watchdog reset) it could be that the USB device is failing (eg. stalling or has a class-error) whereby the USB host will eventually give up and command a reset of the USB interface (this can often take 20..40s).
Therefore check for watchdog reset cycle or set a break point the USB reset detection routine to identify which tyep of problem it is. If you have a USB analyser you will be able to see USB (low-level or class) issues (you can also try Wireshark with its USBPcap plug-in if you are a hobbyist or your project don't have funding for development tools).
You can also use the OpenSource uTasker project which has bullet-proof USB device operation in case it proves to be due to your library rather than application level problems.
Regards
Mark
Kinetis: http://www.utasker.com/kinetis.html
Kinetis K22:
- http://www.utasker.com/kinetis/FRDM-K22F.html
- http://www.utasker.com/kinetis/TWR-K22F120M.html
- http://www.utasker.com/kinetis/BLAZE_K22.html
- http://www.utasker.com/kinetis/tinyK22.html
Networking: http://www.utasker.com/docs/uTasker/uTaskerNetworking.pdf
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