MFRC522 RFID Reader Interfaced With NodeMCU




About: " Work until you no longer have to introduce yourself " Show some love on Instagram & Motivate me on YouTube @TheCircuit

Hello Makers,

I'm back with another Instructable.

Did you ever wonder what is an RFID or how does it work?

If you have noticed in an office before, you would be probably aware of those RFID cards or Tags that would unlock specific doors depending on your access.
Well let’s make a simple NodeMCU RFID reader using the MFRC522 module, and program the NodeMCU to provide access when the right card is detected. This simple example will read the serial number on the Card or Tag, display it in the serial monitor.

Step 1: Materials Required

Here is the list of components required to get started with the Instructable,

Hardware Components

  • NodeMCU
  • MFRC522 RFID Reader
  • RFID Tags ( 13.56 MHz )
  • Bread Board
  • Jumper Wires
  • Micro USB Cable

Software Components

  • Arduino IDE

Step 2: Description

What's RFID?

Radio-Frequency Identification (RFID) is the use of radio waves to read and capture information stored on a tag attached to an object. A tag can be read from up to several feet away and does not need to be within direct line-of-sight of the reader to be tracked. This is the advantage over Bar-code.

> A RFID reader is a device used to gather information from an RFID tag, which is used to track individual objects. Radio waves are used to transfer data from the tag to a reader.

> A passive tag is an RFID tag that does not contain a battery, the power is supplied by the reader. When radio waves from the reader are encountered by a passive rfid tag, the coiled antenna within the tag forms a magnetic field. The tag draws power from it, energizing the circuits in the tag.


  1. Input voltage: 3.3v
  2. Frequency: 13.56MHz

That's all guys lets get into Connections & Coding part.

Step 3: Pin Wiring

Check the schematic and pin configuration to make connections.

Caution: You must power this device to 3.3V!

Step 4: Library Download

Before you download library you need Arduino IDE to get started.

To download Arduino IDE and for NodeMCU setup, you can check my previous instructacle.

Interface Servo Motor with NodeMCU

Here’s the library you need for this project:

  1. Download the RFID library here created by miguelbalboa.
  2. Unzip the RFID library.
  3. Install the RFID library in your Arduino IDE.
  4. Restart your Arduino IDE

Step 5: Reading Data From a RFID Tag

After having the circuit ready

Go to File > Examples > MFRC522 > DumpInfo > Upload the code.

This code will be available in your Arduino IDE (after installing the RFID library).

Then, open the serial monitor. You should see something like the image above.

Write down your UID card ( " Card UID : xx xx xx xx " ) because you’ll need it later.

The next step is to write some code to play with RFID cards.
Download the "RFID_Access.ino" file and open it up in the Arduino IDE.

Then Create a new sketch and paste the code below in the arduino IDE and hit Upload.

You can tinker with it if you like based on the application, or just use it as it is.

Step 6: Demonstration

Swipe the card you’ve chosen to give access and you’ll see an access message popup on serial monitor.

If you swipe another tag with another UID, the denial message will pop up.

That's all makers!

I hope you found this instructable most useful.

You can contact me by leaving a comment. If you like this instructable probably you might like my next ones.



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    15 Discussions


    Question 23 days ago on Step 1

    I'm using a Amica NODE Mcu with esp8266E-12 on it but when I do as told here the Serial is empty. When I try the same code on arduino Uno everything is working perfectly


    5 weeks ago

    FOR me its showing below error,

    ets Jan 8 2013,rst cause:2, boot mode:(3,6)

    load 0x4010f000, len 1384, room 16
    tail 8
    chksum 0x2d
    csum 0x2d


    1 year ago

    I have tested the code & it works.
    The problem was with the connection of SDA, RST. The pin configuration mentioned in the code and the circuit are different, maybe that's why it's not working for most of you all.

    To make this project work :

    Download the RFID_Access.ino from above.
    Upload the code.

    Connection of RFID TO NODEMCU.
    Conenct SDA(SS) to D2
    Connect RST(FLASH ) to D1

    Hope this helps.

    2 replies

    Reply 10 months ago

    Or change the sketch to match the wiring :)

    #define RST_PIN D3

    #define SS_PIN D4


    5 months ago

    Great, post!!!! Now how could you add a HTTP POST request to this sketch? Since you are using this on a ESP8266 and most people are getting them because of the WiFi feature.


    Question 9 months ago

    help me im using node mcu, hve to send from rfid to website


    9 months ago

    Ok, it works in my case, when you use the file above(i mean RFID_Access.ino), you should change the default values of pins RST and SS. D4, D3 in NodeMCU = Pin 2 and Pin 0 in Adruino software, therefore we have

    #define SS_PIN 2 //D4

    #define RST_PIN 0 //D3


    1 year ago

    I did exactely the same but i'm getting this error

    1 reply

    Reply 10 months ago

    Remember to change the PIN numbers in whatever sketch you are using!

    #define RST_PIN D3
    #define SS_PIN D4


    Question 12 months ago on Introduction

    RFID reader is not showing its ID on serial monitor using nodemcu. what should we do?


    1 year ago

    The serial monitor is blank


    1 year ago

    in serial monitor it keeps on displaying the hex generated i wanted that to be displayed only once


    1 year ago

    Hi. Im getting following error:

    signal: bad system call

    Error compiling for board NodeMCU 1.0 (ESP-12E Module).

    Please advice.