USB CDC Code enumerates differently depending on the USB Port.

[guitardenver]

Hello,

I'm using KDS with KSDK V1.1.0 and an MK22FN51212 MCU. I have bare metal projects with no OS. I use the USB hardware on the MCU with the example CDC code.

The problem:

When I plug my device into the front of a powered USB Hub, I enumerate as a normal com port, when I plug it into the back of the USB Hub I enumerate as a "Virtual COM Port Demo" from Freescale and tries to load a driver for it, and lastly I plug it into my desktop tower USB ports and it says it's an "unknown device" .

I do the same test with the same code only this time I put the code on the MK22 Freedom Dev Board. It does the same thing only this time when I plug it into my desktop tower port it comes up as a normal Com port.

When I load the dev_cdc_virtual_com_frdmk22f_bm_frdmk22f example demo onto the freedom board, it works perfect. It will enumerate as a com port no matter what port I put it in.

Lastly, When I put the dev_cdc_virtual_com_frdmk22f_bm_frdmk22f example demo on my hardware, the front and back of the USB hub works fine, but it still does not work with my desktop tower USB ports ("Unknown Device").

Question:

I'm using the same code as the cdc virtual com demo. What would cause this problem?

[guitardenver · Accepted solution]

I have solved the problem.

On the MK22 MCU the VOUT33 pin, the output for the USB 3.3 V regulator, even if the regulator is not enabled, you still need an output cap to filter the regulation. A 2.2uF on the pin.

[audi_mcavoy]

Hey Matt,

Are you certain there was nothing else you did that may have fixed it?

I am running dev_cdc_virtual_com_frdmk64f_bm_frdmk64f (on the FRDM-K64F board of course), and it is enumerating as the "MCU VIRTUAL COM DEMO" on all of my PC's USB ports.

The K64F board already has the capacitor on VOUT33.

- Audi

[audi_mcavoy]

Okay, I got it to work on my FRDM-K64F.

In Windows Device Manager, right-click "MCU VIRTUAL COM DEMO" and select "Update Driver Software."

Browse your computer and install {PROJECT_KSDK_PATH}\examples\frdmk64f\demo_apps\usb\device\cdc\virtual_com\inf\fsl_ucwxp.inf