This project outlines a way to lock and unlock your car using Radio-frequency identification(RFID, For more info please check out http://en.wikipedia.org/wiki/Radio-frequency_identification). The main reason for me doing this is as you will see in the pictures i have an old car(300k+ miles old) and so it doesn't have any of these new key less entry options or a remote control dongle. While it would be simple enough to add a remote it would cost some money and i would rather do something myself. I had a friend who did something very similar to this but having his car only unlock so i thought it would be nice to also have it lock. As with all instructables this is a guide, its what worked best for me by no means is it the most efficient or the easiest hopefully it will give you ideas to go do your own project that's different and share in turn share that with us. This is my first instructable and so if you have any suggestions/questions please don't hesitate to let me know.
This is a basic overview of the order of operations for my system.
- Walk up to car and scan in RFID tag.
- The RFID readers send the tags data serially to the micro-controller.
- The micro-controller then verifies that the tag has the right code to unlock the car.
- If the code is invalide the tag is ignored.
- If the code is valid the micro-controller sends a signal to the switching circuit to unlock the car.
- 25sec later the micro-controller locks the car
I would say that this project is not so much difficult as time consuming. For me the hardest part was the wiring the system into the car. Also something to note, if you have a security system it maybe significantly more complicated depending on the layout of your system. In my car the passenger side window does not go down there for giving me a lot of free space in the door, and the driver side rear door/window are not used giving me the ability to easily place a reader in its window.
Future versions of this project
In the future i plan to modify this project in several ways, I hope to replace RFID with bluetooth and also incorporate the ignition system to allow of keyless/remote start. The next change i will make is probably adding a 2nd RFID reader to the passenger side of the car.
Legal blah blah
RFID is by no means a secure system, no lock is. All that to say if you install this and someone steals your car i am in no way responsible. That said, your car is full of windows, glass is a lot easier to hack into then RFID ;)
Step 1: Switching circuit
On my car to lock/unlock there are two 12V wires, when they are shorted to ground it locks/unlocks depending on which is shorted.
There is not much current when you connect the 12V lock/unlock wire to ground, but i decided to be on the safe side and used N-Channel MOSFET (RFP30N06LE) as my switch, i used 2 one for locking one for unlocking.
So for this part of the system all you will need is 2 RFP30N06LE , and two 10k& resistors, a perf board and wire.
you connect the sourse to ground, the drain to the 12v off of the car, and the gate is connected to a 10k resistor which goes to ground, and the arduino input signal goes to the gate was well.
This is a video i made after installing the switching circuit