I have designed a KL25 microcontroller based board, and I'm now in the testing and validation phase of the development process. I would like to let the board be recognizable from a PC as a serial port. This would give me the possibility to test the USB (layout) reliability making an echoo test. (For example a pc program would continuously send a serial frame and expect the echo from the board).
Is available an example implementing a similar feature, or better, is there a BAREMETAL project implementing the USB Serial Class Device? If not, do you know from where to start?
Thanks in advance to whom could give me some hints on how to implent such a feature.