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For those who don't wish to use such a complex controller, the same task can be accomplished with a 12V relay, a diode, and some C code.
I have connected a 12V relay connected to two pins on my parallel port and powering it with the car's power. When the car is on, the voltage is 14.4V and the relay closes the circuit shorting out the two pins. When the car is off, the voltage drops to around 10V and the relay opens the circuit.
I then have some simple software that monitors for changes to those pins. It does nothing when the pins are shorted, but when the relay opens, it initiates a shutdown process.
How are you turning the PC on?
Its even easier with :
The ignition +12V, resistors and zener diode can be used to apply voltage directly to the serial ports. A customised fake UPS is setup up in the control panel to do the shutdown.
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