Originally Posted by johnsmith10
thanks a lot for your reply..
Actually, I've been askin for help.. one of my friends has a good knowledge of electronics( he is an engineer) but no knowledge of cars
.. and he asked me if I can get any brief description of the microprocessor circuit..
I'd really appreciate your help if you can provide me with any more information to tell him what to do, as i'm very interested in this mod.
Sorry you're on your own with that one!
if all you want is the button to fire the starter motor, ie you turn the key, then press the button and use the key to turn off the car then its easy no problem for most people with a little circuit knowledge, but then whats the point of that!
But if you want the button to do as mine does which is it does everything, ie each step of the original key switch is done by holding the button, start the engine and stop it then you need an intelligent switch controlled by a microprocessor running a program, which you need to write in assembly language! mines about 50 lines of code - you also need to detect when the engine has started to run and turn off the starter motor.
I used a 10f200 PIC chip, but as I said its not easy and not worth the effort - you still need the key because theres no way to bypass EWS on the later BMWs which also need the key to be inserted into the ignition to charge the central locking circuit in the key and then theres the steering lock, and the auto gear lever lock etc etc...