CDC virtual COM port initial connect failure

[hiteshpatel]

Hello,

I have an application that communicates over the OpenSDA virtual CDC COM port (using MSD-FRDM-KL25Z_Pemicro_v107.SDA).

It works fine once connection is established, but I fail to get initial communications working.

Here is the scenario, if I unplug and replug the device into the USB port I reliably see the MSD FRDM-KL25Z

and an OpenSDA CDC Virtual COM enumeration. However, when I try to establish communication with a terminal program

I will generally not be able to unless I first hit the reset button on the board. In some cases the terminal program will

not be able to find the COM port even though it shows up in device manager. Is this something others have seen?

Is this something to do with virtual COM ports? Is there a solution to be able to connect after power cycle without

reset?

Thanks,

Hitesh

[JimDon]

Not sure if this your case but I can tell you this. If your terminal program has the port open, and you cycle the USB port, you will never be able to connect until you exit the terminal program and cycle the port again. This applies to all usb CDC ports.

It will show up in device manager regardless.

[hiteshpatel]

Actually, I was aware of this and even without any terminal program running I see this problem. I have two FRDM-KL25Z's and both display this problem. I have used virtual ports on other devices such as the FTDI chips and have not seen this. I have even tried to send some characters from the Freedom board first (like a welcome message) just in case this helps to kick things off but to no avail. A reset is necessary if the host has to send characters to the device.