Learn how to use RFID readers with your Arduino. In this instalment we use an RDM630 or RDM6300 RFID reader. If you have an Innovations ID-12 or ID-20 RFID reader, we have a different tutorial for you. This is chapter fifteen of our huge Arduino tutorial series. Updated 19/11/2013

RFID – radio frequency identification. Some of us have already used these things, and they have become part of everyday life. For example, with electronic vehicle tolling, door access control, public transport fare systems and so on. It sounds complex – but isn’t.

To explain RFID for the layperson, we can use a key and lock analogy. Instead of the key having a unique pattern, RFID keys hold a series of unique numbers which are read by the lock. It is up to our Arduino sketch to determine what happens when the number is read by the lock. The key is the tag, card or other small device we carry around or have in our vehicles. We will be using a passive key, which is an integrated circuit and a small aerial. This uses power from a magnetic field associated with the lock. Some key or tag examples are shown in the image above.

Step 1: Getting started

In this tutorial we’ll be using 125 kHz tags – for example. To continue with the analogy our lock is a small circuit board and a loop aerial. This has the capability to read the data on the IC of our key, and some locks can even write data to keys. Our reader (lock) example is show in the image above.
These readers are quite small and inexpensive – however the catch is that the loop aerial is somewhat fragile. If you need something much sturdier, consider the ID20 tags used in the other RFID tutorial.
<p>Is this correct? why i got all 255?</p>
<p>My classmates and I were assigned a project using RFID to create an attendance system for our school. We are using Arduino UNO and the RDM6300. We need to first be able to read 6 tags. We are confused as to how we do this seeing that your code uses boolean and we need more than just a true of false. If anyone could please assist us it would be much appreciated.</p>
<p>Awesome :) I've just ordered the RDM6300 and some tags from Hobby Components. Is there a way to get the reader to adjust for 128 and 134.2 kHz chips as well? I want to be able to read all 3 frequencies of pet RFID chips.</p>
<p>How far the RFID reader can measure RFID tag ?</p>
Thanks for putting this out there. I'm hoping to use RFID tags in a project of mine using Bluetooth. I am already using software serial ports for my Bluetooth modules and am wondering if I can use the RFID tags on the hardware serial ports at the same time as the Bluetooth. Any help you can give me would be appreciated! Thanks in advance.
Great Instructable! Excuse my ignorance, but can you also program a reader to recognize or accept other items you may already have with an RFID chip? I'm not sure what other components might be in place to prevent that from functioning. For example, Disney has RFID chip embedded bracelets which are used for a variety of things around the park. Does it seem likely or unlikely that one could use other RFID embedded items to function with an Arduino RFID setup? I've not been able to discern whether or not this is generally possible.

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Bio: Technical person. Visit http://tronixstuff.com for Arduino and other tutorials, projects, kits, reviews and more. VK3FJBX http://arduinoworkshop.com
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