On this instructable I will try to show how to interface a RFID sensor with the Arduino. I am using the RFID sensor from seeedstudio the serial version of it. There are a few parts you will gonna need. I also bought some RFID keys.

UPDATE: Now it works with IDE 021

Step 1: What you gonna need?

- Arduino Board
- RFID Sensor from seeedstudios
- Wires
- Protoboard
- RFID tags (125kHz) from seeedstudios

Step 2: Plugging all together

Connect the antenna on the appropriate pins like the first photo.

Plug the RFID sensor to the protoboard like the second photo above.

Only 3 wires are required to interface, 2 wires for supply and another for the serial line(communication)
The wires as connected as the third photo shows.
On RFID sensor: PIN 1 -> Tx
PIN 2 -> Rx (Not Used)
PIN 3 -> NC
PIN 4 -> GND
PIN 5 -> VCC (+5V)

Tx from RFID board goes to Digital PIN 2 on Arduino Board.

That is all you gonna need to wire.

Moving on to next step, the software.

Step 3: The code

I'm not a software guy, so this code is just for demonstration.

I don't make any kind of checksum at the tags code, but it seems to work fine.

The code is really simple. I used a new library for the serial, using software emulation.

With the two white cards you can deny or allow the access of others keys.

Any doubt, please ask me.

Edit (05/11/12):
code update for new Arduino version

Step 4: Results!

There is no LED, sound or LCD for debug or visualization, just through the serial line.

The video demonstrate how to use the software. I didn't post any kind of explanation as text on the video. I hope that the images spokes more then words, xD

Any doubt or suggestion, feel free to ask, or correct me.

Please, if you like it, rate it,

thank you

Thanks for the instructable man, really appreciate it.&nbsp; I've been wanting to do something with rfid and this is going to help me out big time.<br />
Nice, thank you for the positive feedback. xD<br />
<p>Hello, how can i add more tags ? </p><p>what i need to change in the code?</p><p>thanks</p>
<p>Just a few quick questions: Which arduino board did you use for this project? Also, I see that pin one TX of the RFID sensor is being connected to digital pin two of the arduino board, is this digital pin two a special pin such as RX or is it a normal digital pin? Thank you for a great instructable! </p>
<p>The board is a old Arduino Duemilanove.</p><p>I use the digital pin with a serial software to connect with the RFID board so the original serial port can communicate with the computer for debug purpose and interacation.</p>
<p>Hi, thanks for this great tutorial. I have this same RFID module from seeedstudio but want to make it work with 134 kHz RFID tags used for animal tagging with ISO 11784 &amp; 11785. Is that possible or not? I've searched the web but couldn't find anything specific to this and SeeedStudio just referred me to their Wiki page. What I was able to find out is that the frequency fot this specific antenna is not a problem. </p><p>Thanks in advance.</p><p>Regards</p><p>Tinus</p>
Hello Tinus,<br><br>With this especific sensor I dont think that it will work with this animal tag because of the diference between the two frequency.<br><br>Regards
<p>Thanks for a really good tutorial it really helped me out, i was wondering if you could help me, my project require reading a static rfid, i.e. when the arduino is turned on it reads the rfid card that currently on the reader. Is that possible or does the card need to move be able to read it</p>
That is a good question, never tried this way.<br>I really don&acute;t have this answer right now.
<p>please help i dont understand how to program the tags, what does the line in the code mean '&quot; //change this ID with your own card TAG' please help fast!</p>
<p>I have the same problem. The card has a long number but when I put the number in the program, nothing happens. The serial monitor just shows &quot;Serial Ready&quot; and &quot;RFID Ready&quot;. But nothing else. Please tell me in detail, how you solved the problem</p>
Can you send me your code and your card ID
<p>You need replace the code by your own ID form your card</p>
I tried that but the number is very long, it has a space and a comma in it so what do i do with that?
<p>send me a print of the serial reading when you read a tag</p>
<p>It doesn't read anything, where do you get the tag ID number? on the cards there is a number printed on them, one is '0000946210 014,28706' and the other is '0001361049 020,50329' so are these supposed to be the id number?</p>
<p>Have you find what is the ID number of the card? I have the exact same problem here! </p><p>I have : '0006527268 099,39204'</p><p>and : '0006512977 099,24913'</p>
<p>After uploaded the code, there is any message on the serial monitor?</p><p>When you approach the tag to the sensor, appears anything on the serial monitor?</p>
<p>This may have been the obvious answer from the beginning but does this work with arduino uno?</p>
<p>Have you tried to upload the code without any errors?</p>
<p>Okay i solved it, with arduino you have to switch the wiring round between the RFID module and the Arduino, you have to wire the RX on the RFID module to the TX on the Arduino and the TX to the RX. </p>
<p>Hi, just a noob question:<br><br>You're using the RFID Cards and Keys here, right? Is it possible to use the RFID stickers(the ones that can be placed on equipments or someting) as a substitute? as long as it's 125Khz?<br><br>Thanks.</p>
I think it is possible, but the distance that you can read the sticker may be smaller than the read bycard.
<p>Hi, thanks for the reply. I had used a 125Khz card instead. So I tried the code of brenryan since I just need a simple program that displays the card's id(also modified 1 line of the code &quot;tag=tag.substring(1,13);&quot; replaced 13 with 19 since my card has 18 digit code. Anyway, now I'm facing a different problem, do you have any idea why the output looks like this?<br><br></p>
<p>I'm probably way too late, but the reason is because the serial monitor converts the number into a character, try <strong>Serial.println();</strong> instead</p>
<p>Super instructable man..</p>
Thank you for the feedback<br>
<p>If I have Arduino Uno, Ethernet Shield and RFID Module ID-20LA. May I know how to connect the circuit? </p>
Never tested this two shields together.<br>My sugestion is first, make de arduino and the RFID modulo works together.<br>After this, try the same thing but now with the arduino and the Ethernet Shield together.<br><br>After both works, try to make it works together.
<p>do you have some tutorials about rfid with magnetic lock? Thanks ?</p>
I do not have any. But on Google YouTube can find some example
<p>Thanks you for your wonderful tutorial. I have implemented it with an addition of RF to use it as a Magnetic Door lock system. In order to do that, i had to use a Ethernet shield to use the card database. But after a few days of use my Ethernet Shield stopped working. I cant seems to figure out why that happened. One of my guess is the RF+RFID circuit is drawing too much current (more that 500mA). And so it fried the W5100 ethernet chip. My guess is based on the indication that my RFID cant seems to work with the current supply from the USB cable and i had to use the DC Power jack to power the System.<br></p><p>My whole System:<br>Arduino Mega(chinese knock off)+w5100 Ethernet Shield(Chinese Knock off) +RF Transmitter+Groove RFID Reader ( http://www.seeedstudio.com/depot/grove-125khz-rfid... Should i give the RF+RFID circuit a independent power source? <br></p>
I don&acute;t think that you gonna need a independent power source only for the RF + RFID circuit. Try to use a power source of at least 2A on your arduino Board and disconnect it from the USB cable.
<p>it's gonna be our first projec from development programme , quite a good tips for the beginner , kindly support your kindess . thankyou =3</p>
<p>Glad we can help.</p>
<p>Sorry my comment didn`t go through .</p><p>I get an error with my setup arduino uno v3 witch ID-12LA . I have 4 cards that are read the same and the characters are messed up .</p><p>This is what i`m getting from every card : &yuml;&yuml;&yuml;&yuml;&yuml;&yuml;&yuml;&yuml;&yuml;&yuml;&yuml; instead of numbers .The baud rate is set to 9600 in the code and in the monitor. I have been searching for a solution for hours now and can`t seem to find it , any help would be awesome</p>
You are using a different sensor from my project. I can't sau that this code will work with your shield<br><br>Have you tried this example from Arduino website? <br><br>http://playground.arduino.cc/Code/ID12
<p>Hi! Nice instructables! What is the difference between RFID Tags and RFID cards?</p><p>Thank You!<br>marC:)</p>
<p>None, just the size and shape.</p>
<p>sir kindly again post the vedio in which mention software type and how to add /delete users of tags.</p><p>which code is best one between the two of them.please help me sir...........</p>
<p>tell me either arduino uno will remain best for finger print scanner and rfid or other type??? and also tell me which rfid is available with data base /software...? and </p>
<p>Hi, thanks for the tutorial, it worked perfectly on my Arduino Mega 2560 (just changed the RX to digital 50).</p><p>Do you know if I can read the Sticker version of RFID with this componente or do I need some other type? can you recommend me one? Thank you very much!</p>
<p>Hello! I'm quite confuse on my connection to arduino uno to rfid rc522 don't know where should I connect the pins from rfid rc 522 to arduino uno.. Pls do show some pics for their connections or guides... Need help also for a sample module to test my rfid rc522 if its working or not using my arduino uno... I really appreciate your great help..</p>
<p>can you help im having issues compiling code on the link it one. Not sure if I have the right library. </p><p><br>sketch_jan28a.ino: In function 'void loop()':<br>sketch_jan28a.ino:30:40: error: 'add' was not declared in this scope<br>sketch_jan28a.ino:31:45: error: 'del' was not declared in this scope<br>sketch_jan28a.ino:32:37: error: 'verifica' was not declared in this scope<br>Error compiling.</p>

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