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TMS320F28069: USB Virtual COM port - issue with multiple USB connection and disconnection on F28069U once in VCP mode

Part Number: TMS320F28069

Tool/software:

Hello All,

We are using the USB on F28069U/F/M at the heart of our product, we basically create the virtual COM port inspired by "usb_dev_serial" example, in general, the application works well, however after several years in the market, we realize that for our costumers it's very important to be able to connect and disconnect many times to the port due to various reasons, however, we found that occasionally the USB can not get connected anymore, for instance after 3-5 attempts of Connection, sending some packets, disconnection, suddenly the next Connection doesn't work.

So my questions are as below:

  1. How to understand if the Host is "really" disconnected? I see a variable called bConnected, which stays as 1 even if I disconnect the COM port from the PC side, it goes back to Zero only if I fully disconnect the wire of USB
  2. How to safely recover the USB for the next connection? what registers should we look and change?
  3. How to safely Disconnect and Connect the COM port within the Firmware? ( when I call CDCTerminate function, the COM port on the PC stays there, even if I disable the USB clock, I still can see the COM port staying there)

Thanks

John