Arduino RFID reader with computer serial client
Python Java
Latest commit 650b76b Oct 6, 2010 Matt Williamson Added link to youtube
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Arduino RFID Authentication

This is an RFID authentication system. It allows a person to place an RFID tag within proximity of the reader device (usually 5-6 inches with this reader) and it will look up the tag in an SQLite database to check if it should grant access. If authorization is granted, the hardware device will turn a servo motor into a second position. The primary application of this being the unlocking of a door. This implementation also speaks aloud "Access Granted" or "Access Denied" if you are running the server on OS X. You can modify the source to use something like flite on other OSes. This project is very easily modified to do any sort of task. Some ideas are:

  • Door locking (default implementation)
  • An employee punch-in/punch-out system
  • Real world item identification (affix a tag to every day items, such as your wallet; when scanned, open a web banking web page. attach one to your phone to initiate a Google Voice call, etc.)
  • Russian roulette with RFID tags instead of guns

Here it is in action.

Via Youtube


To make this RFID system, you'll need the following hardware:

  • 1 Arduino (buy them from Amazon
  • 1 Servo (I like Hobby Partz because they are cheap) you don't need this if you are not unlocking a door
  • 1 RFID Reader module (buy from your local Radio Shack or Parallax) $8 if you get lucky and find one at Radio Shack
  • Some jumper wires to wire the whole thing together



Wire it Up

You can use the image schematic/reader_breadboard.png to reference the wiring diagram. Basically you just need to wire the pins as follows:

  • Arduino pin 8 -> RFID pin SOUT
  • Arduino pin 9 -> RFID pin /ENABLE
  • Arduino pin GND -> RFID pin GND
  • Arduino pin 5V -> RFID pin VCC

  • Arduino pin GND -> Servo wire BLACK

  • Arduino pin Vin (9v) -> Servo wire RED
  • Arduino pin 3 -> Servo wire YELLOW


You should end up with something like this.


Close Up

Program the Arduino

First you need to install the NewSoftSerial library for Arduino. Read the Arduino docs on how to install a library.

Plug the Arduino into your computer and open the sketch sketch/rfid_sketch.pde with the Arduino IDE. Select which serial port to use for the Arduino (Tools->Serial Port on OS X). Click the upload button to write the sketch to your Arduino. You may need to try a few different ports before it works. Write down the port name, we'll need it later. It should look something like /dev/tty.usbserial-A70064Mh or COM3. It will probably be different for your machine.

Set Up the Server

Install the pySerial serial library for python. If you have setup tools installed, you can just run easy_install pyserial.

Open with a text editor and look for this line: serial_port = '/dev/tty.usbserial-A70064Mh'. Change the /dev/tty.usbserial-A70064Mh to the serial port you wrote down in the previous step.

First, we'll run the server to watch for the RFID tags we want to allow. Open a terminal and cd to the project directory. Then run python serve. This tells the python server to listen to the serial device for RFID tags. It will print debug information into the console.

wraith:rfid mwilliamson$ python serve
Starting serial server...
Connected to arduino. Awaiting RFID scans.
Checking tag: 0F03042E80
Tag access denied.

Hit ctrl-c to kill the program. Now we have a tag we can enable: 0F03042E80. We'll use the enable command to enable it.

wraith:rfid mwilliamson$ python enable 0F03042E80
Added tag with access ENABLED

Now that we've added the tag, we can scan it successfully. You should see the servo spin, or a least the built in LED on pin 13 of the arduino will light up.

wraith:rfid mwilliamson$ python serve
Starting serial server...
Connected to arduino. Awaiting RFID scans.
Checking tag: 0F03042E80
Tag access granted.

You can revoke access to a particular tag by running the disable command

wraith:rfid mwilliamson$ python disable 0F03042E80
disabled access for tag


If you see the following, make sure your Arduino is plugged into your computer and you correctly set up the serial port in

wraith:rfid mwilliamson$ python serve
Starting serial server...
Could not open serial port.
Edit and make sure you define serial_port properly.