Boards without SERIAL_PORT_USBVIRTUAL

[maxholgasson]

When using a SAMD21 on a custom pcb without a USB connector and commented out (//#define SERIAL_PORT_USBVIRTUAL SerialUSB) in variant.h there appears an error.

Would it be possible to add a check whether it's defined in variant.h or not?

Error message:
ArduinoLowPower-master/src/samd/ArduinoLowPower.cpp:41:6: error: 'SERIAL_PORT_USBVIRTUAL' was not declared in this scope if (SERIAL_PORT_USBVIRTUAL) {

[facchinm]

Hi @maxholgasson ,
the right approach to remove USB from a SAMD board is adding this line to its boards.txt entry:
<board>.build.usb_flags=
It removes all USB initialization code too.
Then, the bug you reported is real, so if you could send a PR I'd be glad to merge it (to preserve attribution)