USB virtual com issue

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by pra18 on Fri Oct 17 05:56:28 MST 2014
Hi all,

When I do a single stepping of the CDC VCOM example  for LPCOpen 2_12 for ngx 4330 ,I see a USB device not recognised message in my PC and also there is an Unknown driver showing up in the  PC's Device manager's  USB controllers option  and the VID/PID both are shown as 0.

On the other hand if I remove all breakpointsand run the code, then a LPC USB VCOM COM4 is shown up in ports and LPT option in the Device manager.
also the VID PID shows up correctly.

Can anyone help and explain why this occurs ?
does it occur because there is a delay introduced when stepping ?

This appears to be the same on my custom board when I try to adapt and integrate this VCOM example into my custom firmware. I see this problem even when the firmware is running continously and there is an unknown device shoing up in the PC and unrecognised device.

Again here, from the time the firmware starts up and the time the USB is initialised , there are many things done for device firmware , and this adds to a delay ( as above case)

But when I remove the USB cable and connect it back this Unknown driver disappears and appears in the Device manager.

I have also attached my USB initialisation code so anyone can help if i am initilaising my USB1 correctly or not and I am missing some critical step in my USB1 initialisation
that might be causing the problem.

Thanks in advance,

Original Attachment has been moved to: USBInit.txt.zip