car security keypad options.
I am lookingto build a small numeric keypad to control a relay to disable the starter circuit on the car.
I guess what I am looking to build is something like what was used on the cars in transporter I and II if anyone remembers this.
Would it be possible to use a cut down keyboad from an old laptop or something similar? i would like to fit it in the ashtray of my car (about 3x5 inches). I have an old PDA with a touchscreen that is pretty much useless now (badly out of date, slow and dead battery), could this be adapted to make a touchscreen keypad?
The problem I can't seem to wrap my mind around is how to make a controller that would accept a code like 2-5-1-4 and output a signal to a relay to energize. Maybe I could use the keypad and controler that the older ford crown victorias have on the doors to unlock the doors with the punch in code?
Anyone have any ideas?