Use my car Key FOB

Projects General Guidance
1

I'm wanting to try and use my current car Key FOB to unlock/lock the door to my room. To my basic understanding of how FOBs work, they send out a specific RF signal that's already been pre-programmed.

I know there already exists key fobs that will interface with the arduino, backup, but I don't want to use a secondary FOB to unlock the door. I'd like to use only one FOB for the car and my room.

There will be some kind of motor on my deadbolt that will be used to turn, or push, the deadbolt (haven't decided how to work the bolt yet), this will be driven by the arduino, which is connected to the RF receiver which takes the unlock/lock signal from my FOB.

How could I go about getting the signal from my FOB and have the arduino use it?

2

You can only do it if your keyfob works on the same frequency as one of the easily available rf receivers for Arduino.

However, the best you can do is to have your door open when ANY signal comes in on that frequency. Your keyfob most likely has encryption/rolling code, and there is no way you can have the Arduino 'learn' its behavior.

And ranges on car keyfobs are quite long, you may end up unlocking your door when you unlock your car. Using the same keyfob is just a bad idea all around.

3

Darn, was hoping there was some way to get the frequence/code from the FOB without using a second. The distance wasn't an issue, my door is way outside the reaching limit of my car

Guess I'll just look into a second FOB. Does anyone have any recommendations?

Thank you for the answer :slight_smile:

4

Just search for any 315 or 433 MHz keyfob sets.

In fact, if you're just working a door lock, you can look for a relay module with RF onboard so you can skip the Arduino altogether.

5

It probably won't require the arduino, but you may be able to use the receiver module from the same make & model of car. Probably not anything particularly current, but a lot of older cars could have replacement keys coded into the central locking system by the user. Coding to start the car was more difficult, but just the central locking was easy enough.

I can do it on my 2003 BMW with a particular sequence of ignition key operations and button presses. I believe a lot of other cars are similar. Search the internet to see if it can be done on your car.

Ian.