Features
--------

- Displays:
    . speed (not yet implemented)
    . tacho (not yet implemented)
    . km (not yet implemented)
    . day km (not yet implemented)
    . time
    . date (not yet implemented)
    . alarm (not yet implemented)
    . temp inside with min/max
    . temp outside with min/max
    . battery voltage (digital and analog)
    . average speed (not yet implemented)
- Backlight display of 4 x 20 chars. Semi-graphics.
- Powered by car battery.
- KM and dayKM periodically stored in EEPROM, so no backup battery needed.
  (not yet implemented)
- frost alarm (beeper)
- contact off but lights still on alarm (beeper)
- overvoltage (defective regulator) alarm (beeper)
- precision clock with x-tal, temperature compensated in software

Connections
-----------
- Ground
- +12V
- +12V contact
- +12V light
- outside temperature
- bobine
- speed

User interface
--------------

2 buttons: mode, set

mode: changes display
set: scrolls cursor to digit that has to be changed
  (mode advances digit under cursor when in set mode)


Example display
---------------
Ü Û ß

ÜÛ ß
Ü Û ß

    ßßÛ Ûßß   ßßÛ O  
ÜÛÜ ÜÜÛ ÛÜÜ     Û    
 ß  ÛÜÜ ÜÜÛ Û   Û     
*12.5V *18:47 *18.3ø