Multiple Serial ports on USB

Wanted to create multiple Serial port project that would use the 4 hardware serial ports on an Atmel D21 and expose each as a separate virtual serial port (COMx on windows).

I have been able to create two ports, the stock port and a second one but no more show up, I suspect there might be an endpoint limitation, but unsure if that is a hardware or software issue.

Any suggestions?


…so hardware UART or USB-CDC (“virtual COM port”) stuff? Did you implement it with SERCOM?

Also, the people at the Adafruit SAMD core (GitHub - arduino/ArduinoCore-samd: Arduino Core for SAMD21 CPU) might know more.