nxpUSBlib cdc issue

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by mrob on Mon Oct 22 16:47:30 MST 2012

Has anyone here had success using the nxpUSBlib VirtualSerialDevice demo?  I'm using v0.97 of the nxpUSBlib, and I'm having some issues.

I have a simple Visual Basic terminal program that has been working great for a few years.  When I open the virtual com port from my device, communication seems to work just fine.  The issue is when I try to close the port, I get an exception "IOException was unhandled" "A device attached to the system is not functioning."

From some testing, this only seems to be an issue if I send more than 8 bytes to the port at one shot.  If I send a string of 8 or less the port closes fine, but if I send 9 or more I get the error.

I tried the demo's mentioned here: http://www.lpcware.com/content/forum/usb-rom-driver-examples-using-lpcxpresso-lpc11uxx
Those seem to close just fine, but the drivers needed re-installation each time the device was plugged in.

I'm trying to compare the two examples to see what they have different or in common.  Does anyone have any suggestions on where to look?