Which peripheral does SAMD51 Metro M4 use to communicate with computer

[jamwheeler]

Hello,

How can I find which peripheral is being used to communicate with the computer? When I type in "Serial.write(foo)" which peripheral is being fired?

[Klaus_K]

You can check the schematic of the board. There you can see that the USB connector has two Signals D+ and D- which are connected directly to the SAMD PortA.

https://learn.adafruit.com/assets/53093

This means the SAMD USB peripheral is used to communicate with your PC. For this it creates an endpoint as a USB communications device (USB CDC class).

Dependend on your system when you go to the folder where you installed the SAMD library, you will find the CDC.cpp file with the Serial_::write function.

..\AppData\Local\Arduino15\packages\adafruit\hardware\samd\1.5.7\cores\arduino\USB