Tom Russell

Important changes to forums and questions

All forums and questions are now archived. To start a new conversation or read the latest updates go to forums.mbed.com.

10 years, 1 month ago.

Windows needs to install driver software for your USB_CDC

My PC will no longer communicate to either my KL25Z or 11U68 using the Serial USB interface. When I plug the board in to load a program, I get "Windows needs to install driver software for your USB_CDC" I tried running the mbed serial installer, but no change. I tried updating the driver and pointing it to a folder containing Serial.inf used for USB device mode, but it did not think that was a driver. The USB device interface works as a virtual COM port and comes up as mbed Serial in the device manager. When plugged into the programming USB connector, it shows up as USB_CDC but unknown. Everything works fine on a second PC so clearly something is corrupted on the PC. Any suggestions for tracking this down?

Thanks, Tom

1 Answer

Sam Grove
10 years, 1 month ago.

Could you try the following? With the device disconnected, open a cmd prompt window as administrator. To do this right click on cmd.exe and choose run as administrator. Then type:

C:\>SET DEVMGR_SHOW_NONPRESENT_DEVICES=1
C:\>devmgmt.msc


When this opens a new device manager try view -> show hidden devices

At this point you should see all the instances (or maybe just one) of the CDC device and have the option to remove and uninstall driver. Remove all instances of this device and when complete close the device manager and try to re-install the driver after reconnecting the device.

A good suggestion but one I have already tried. I have also used a very handy program called USBDeview and removed a bunch of old drivers.

posted by Tom Russell 21 Oct 2014

Just saw another computer with this problem and we resolved it. Not sure which of the steps but can you try them and let me know if any are successful?

  • Go to the USB_CDC and install the driver from C:\Program Files\mbed\drivers This may be (x86) or
  • When you did the remove devices did you also remove the HID endpoints (CMSIS-DAP) and and Disk adapter (mbed microcontroller) and composite device entries?
posted by Sam Grove 28 Oct 2014