USB detected by PC as unknown device

Legacy General
1

When we plug a USB cable between our own WMP design and a PC, the PC always picks it up as an “unknown” USB device.

Here is a bit of background:

  1. We based the USB port connection in our own WMP100 design on the circuit diagram examples of the Wavecom documentation for the development kit user guid and the WMP Design Guidelines.
  2. We also installed the USB driver that we received from Wavecom on our PC.
  3. We issued the command “at+wmfm=0,1,3”
  4. When we type “at+wmfm?” we see the following which seem to indicate that the command has been accepted:
    +WMFM: 0,2,1,1
    +WMFM: 0,2,2,0
    +WMFM: 0,2,3,1
    +WMFM: 1,2,4,0
    +WMFM: 1,2,4,1
  5. When we disconnect the USB from our own product and plug it into the Wavecom Development board, then the PC immeadiately picks up the WMP100 as a Wavecom modem. This makes me suspect our own hardware, but we have checked and re-checked and our hardware design looks exactly like the circuit diagrams on the Wavecom documentation.

Now the question : Is there anything else we need to do to use USB with our WMP100 design?