Movement sensor

[Bruce]

If this is something that will only be activated when someone is in the drivers seat, why not use a simple pressure switch in the drivers seat?

[mister_e]

or the brake switch?

Or detect if the battery voltage go under 12 volts for a few hundred milliseconds (that what OLD remote starter used in the past to see if the car had started)

I could say, use the lighter plug.. but some are connected directly to the battery.. so...

[sayzer]

1. Attach a weight on a pot pulling it down to ground. When the car moves and is moving it will change the pot reading in small steps by moving it back and forth. When the car is not moving for sometime, say 30secs or 60 secs. etc, then you will read a constant pot value AND know that the car is stopped.

OR
2. Short the wiper so that driver will always know that the GPS is running.

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[Lotondo]

Thank you all for the good ideas.
I'll try to find the best one from them.

bye
Lotondo

[Ron Marcus]

Marty Kaiser made a motion control switch that can't be beat for simplicity. He took a short length of stainless ball chain (like a light switch chain), and hung it in a metal box similar to the suggestion above. The PIC would sense a change of state which would happen if the box/tube was jiggled even a little. For GPS, a vehicle passing would just record another way point. For an alarm, I would count the number of changes in a 5 second time, and if it exceeded a certain amount it would trigger the driver seat detonator ,tear gas grenade, or wake the trained Rotweillers in the glove compartment.