"Unknown Device" when attempting USBCDC example

Discussion created by lpcware Employee on Jun 15, 2016
Latest reply on Jun 15, 2016 by lpcware
Content originally posted in LPCWare by JSchwendeman on Mon Apr 18 19:09:42 MST 2011
Hello Everyone!

I'm attempting to implement the USB soft connect transistor as wired in the following schematic (I also use the reset and bootloader circuitry shown): http://www.microbuilder.eu/Files/Projects/LPC1343RefDesign/LPC1343_Schematic_v1.6.pdf

The USB bootloader works as expected, and I am able to download code and verify operation (blinking lights, read buttons, etc).  However, when i attempt to deploy the USBCDC example, upon reset my computer (XP 32bit) complains about an "Unknown USB" device.  Attempting to point to the vcom driver, windows complains that the driver doesn't match the hardware.  Checking in the device manager, I can see that the VID and PID for the device are both called out as _0000 (doesn't match the PID/VID in the .inf, makes sense).  I checked the config.h code included in the example, and verified that they match those in the lpc134x-vcom.inf file.  Recompile, still no luck.  I thought there might be some issue with the micro expecting USBVBUS to be low on reset, and then high later on, so I placed a switch in between, allowing me to toggle USBVBUS, still no luck.

Now here's the interesting part.  In the microebuilder code examples, there are some test binaries that allow one to test out their hardware after assembly.  If I load the usbcli.bin example, upon reset the device enumerates correctly, I'm able to point to the driver and away we go. 

Does anybody see any glaring differences between the code in the USBCDC example and my hardware that might be causing this issue?

Questions and comments are greatly appreciated!