for first release:
	USB serial interface

	PWM (or remove unported code) 
	ADC (or remove unported code)

later:
	Write more board modules for Zerphyr's many boards.
	
	Generate board definition files from zephy's metadata (devicetree
	etc). Unfortunately does not include GPIO pins beyond the user led
	and switch for most boards.
	
	Also see arduino-copilot's TODO list for some generic ideas that
	are also applicable here.
	
	Zephyr has many libraries and capabilities, that could all be
	supported.