Recently I've been with working with Matt Little of Re-Innovation on firmware for some pedal powered educational game systems. Today I wrote some RGB LED effects, which add a nice dash of colour to the grey British winter.
These effects are triggered at the end of a pedal powered challenge - the player pedals a static bicycle which turns a generator which in turn powers the system and charges a large super-capacitor. When the capacitor voltage reaches some threshold, a random effect is triggered as a reward. The effect lasts until the suprt-capacitor voltage drops below a second, lower threshold, which takes about a minute.
The system is is controlled by an Arduino Nano, and has two different game modes. Source code for the firmware is available on github.