Picture of How to connect Arduino and RFID
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?

Picture of What you gonna need?
- Arduino Board
- RFID Sensor from seeedstudios
- Wires
- Protoboard
- RFID tags (125kHz) from seeedstudios
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epidemicz5 years ago
Thanks for the instructable man, really appreciate it.  I've been wanting to do something with rfid and this is going to help me out big time.
otaviousp (author)  epidemicz5 years ago
Nice, thank you for the positive feedback. xD
abirm12 months ago

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.

My whole System:
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?

otaviousp (author)  abirm12 months ago
I don´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.
CeqapR2 months ago

it's gonna be our first projec from development programme , quite a good tips for the beginner , kindly support your kindess . thankyou =3

otaviousp (author)  CeqapR2 months ago

Glad we can help.

VladB23 months ago
otaviousp (author)  VladB23 months ago
VladB2 otaviousp3 months ago

Sorry my comment didn`t go through .

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 .

This is what i`m getting from every card : ÿÿÿÿÿÿÿÿÿÿÿ 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

otaviousp (author)  VladB23 months ago
You are using a different sensor from my project. I can't sau that this code will work with your shield

Have you tried this example from Arduino website?

nodoubtman4 months ago

Hi! Nice instructables! What is the difference between RFID Tags and RFID cards?

Thank You!

otaviousp (author)  nodoubtman4 months ago

None, just the size and shape.

JakeW45 months ago

please help i dont understand how to program the tags, what does the line in the code mean '" //change this ID with your own card TAG' please help fast!

otaviousp (author)  JakeW45 months ago

You need replace the code by your own ID form your card

JakeW6 otaviousp5 months ago
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?
otaviousp (author)  JakeW65 months ago

send me a print of the serial reading when you read a tag

JakeW4 otaviousp5 months ago

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?

zejudoka JakeW44 months ago

Have you find what is the ID number of the card? I have the exact same problem here!

I have : '0006527268 099,39204'

and : '0006512977 099,24913'

otaviousp (author)  JakeW45 months ago

After uploaded the code, there is any message on the serial monitor?

When you approach the tag to the sensor, appears anything on the serial monitor?

JakeW4 otaviousp5 months ago

This may have been the obvious answer from the beginning but does this work with arduino uno?

otaviousp (author)  JakeW45 months ago

Have you tried to upload the code without any errors?

JakeW4 otaviousp4 months ago

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.

FaiquahL5 months ago

sir kindly again post the vedio in which mention software type and how to add /delete users of tags.

which code is best one between the two of them.please help me sir...........

FaiquahL FaiquahL5 months ago

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

edugr6 months ago

Hi, thanks for the tutorial, it worked perfectly on my Arduino Mega 2560 (just changed the RX to digital 50).

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!

Hi, just a noob question:

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?


otaviousp (author)  jess.delamerced6 months ago
I think it is possible, but the distance that you can read the sticker may be smaller than the read bycard.

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 "tag=tag.substring(1,13);" 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?


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..

LeoA57 months ago

can you help im having issues compiling code on the link it one. Not sure if I have the right library.

sketch_jan28a.ino: In function 'void loop()':
sketch_jan28a.ino:30:40: error: 'add' was not declared in this scope
sketch_jan28a.ino:31:45: error: 'del' was not declared in this scope
sketch_jan28a.ino:32:37: error: 'verifica' was not declared in this scope
Error compiling.

RiaanBod11 months ago

What happens if your arduino restarts or lost power. Do you have to re-program the TAGs again?

otaviousp (author)  RiaanBod9 months ago

On this code you have to reprogram

SimonT2 made it!9 months ago


VishalG111 months ago

Hi, Mandeep for ES-125R Rfid reader you can get complete support by writting mail over this Email, contact@elesof.com, or you can call them directly +91-7533036999.

me happy to help

great. good. amazing.

kamra1 year ago

I have one ES 125 R, please tell me how to connect it to arduino.
RFID pins of ES 125R as such
A0 , A1 , O/P , GND , +5V , R , TX


I have the same ES125R, have you been able to figure out as to how to use it, if so would your share it, thanks

otaviousp (author)  MandeepS11 year ago

A simple search at google returns this schematics

Just connect your TX pin from ES 125R to your RX pin at your Arduino board.

Power UP your ES 125R module, make a program to continues read the serial port at 9600 baud rate, open the serial monitor, approach the rfid tag to the board and see if something has been send through the serial port.

If it work or doesnt works, please tell me.

otaviousp (author)  otaviousp1 year ago

Forget to upload the image of the schematic

AroojZ2 years ago
Hi I have arduino Mega ADK, Here is a preview of it, http://arduino.cc/en/uploads/Main/ArduinoADK_R3_Front.jpg can you tell me where to connect the TX of RFID in the arduino board? I,m an extreme beginner so if my question is stupid please bear with me. Just tell me the exact pin number on which to attach from the arduino board's picture! Thanks in advance.
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