Problem: Arcade machine buttons have provision for a lamp to illuminate
the button.  Originally this was a filament bulb, nowadays usually an LED.
We want to replace these with full-color RGB modules.  However the housing
only provides two terminals.

Solution: An RGB LED module that requires ony two external connections,
one of which is ground.

firmware/	Code that runs on the LED module
pcb/		PCB design
libowled/	Arduino library for controlling LEDs

The v1 PCB does not work as-is.  The pull-down resistor shoould not be
populated, and a 1nF bypass capacitor added in parallel with the schotty diode.