I wanted to make an easy and secure way to enter my garage. RFID was the best way to unlock my door, even with my hands full I can unlock the door and push it open! I built a simple circuit with a basic ATMega 168 arduino chip and a ID-20 RFID reader to control an electronic door lock.
The circuit consists of 3 separate parts, a Reader to read RFID tags, a Controller to accept data from the reader and control the output of the RGB LED and the Electric door lock. The door lock is first installed in a door and tested with a 9v battery to ensure correct installation. In most cases you want a Normally Open circuit on the door lock, or Fail Secure. This means the door stays locked when no current passes through it. When 12vDC is passed through the electromagnet in the door lock, a plate in the lock gives way and allows the door to be pushed open freely.
The reader is placed on the outside of the door and is separate from the controller on the inside so that no one can circumvent the security by breaking open the Reader and trying to short circuit the reader. The controller receives serial data from the Reader and controls the RGB led and the Door lock. In this case I have put both on separate bread boards for testing. Here is a video overview of the system in action Read on to see how to build one for your self!
All of the code, schematics, and PCB designs have been tested and refined. They are all posted here as of 8/9/2010
Updated video of the final system installed and working.
Step 1: Parts Needed
ATmega168 with Arduino Bootloader $4.95
Crystal 16MHz $1.50
Capacitor Ceramic 22pF $0.25 (x2)
Resistor 10k Ohm 1/6th Watt PTH $0.25
Mini Push Button Switch $0.35
Triple Output LED RGB - Diffused $1.95
Either one of these, 20 has better range, 12 is smaller
RFID Reader ID-12 $29.95
RFID Reader ID-20 $34.95
RFID Reader Breakout $0.95
Break Away Headers - Straight $2.50
RFID Tag - 125kHz $1.95
TIP31A transistor (radio shack/local electronics store $1.50)
Door Lock is from ebay.
Door Fail Secure access control Electric Strike v5 NO $17.50 (kawamall, bay)