I now need to define the main control loop; and implement it.

• One reading every 30S and then decide how to set fan.
• Power Control
  • Vmin->11.8V : Powersave mode; no activity, wake every 30s to take and process a voltage reading. Ignore button
  • 11.8->12.6V : Low Power Mode(s); start running the fan; limit max speed. respect quiet/off overrides
  • 12.6->Vmax : Full power mode. respect quiet/off overrides
• Fan Control
  • Need to think about this
• User Control
  • Off/Quiet/Idle
• Average readings; discard outliers
• Testing will be tricky.. I'll need to 'fake it' somehow for the humidity/temp readings.
• I'd like to use interrupts and have the controller sleep between readings/decisions.