Recently, I am working on a USB virtual comport example (dev_cdc_virtual_com_twrk65f180m_mqx_twrk65f180m) from KSDK 1.2.0 under KDS 3.0.0. After success compiling USB stack and application, I was able to run the application on my K65 tower board without problem. The tower board has two USB connected, one is for power (J7), and the other (J15) is for data to the PC. The data I entered from Tera Term can be looped back to PC. However, when when I disconnected and re-connected the data USB wire, the Windows shows "USB Device Not Recognized" message, and shown a "Unknown Device" in the device manager. If I reset the board by pressing the reset button (SW1) or power cycle the board, the USB enumerated and everything worked fine.
This is similar issue I had several years ago with Coldfire MCU and we ended up using a real com port. I am wondering if this is something I can improve on the application, or this is a issue on the Windows OS. Please let me know if you have any idea or suggestion. Thanks!
Figure: The virtual comport enumerated and port works fine after power on the k65 tower board.
Figure: Windows shows "USB Device Not Recognized" and port is not enumerated after reconnect USB cable