Using RC522 RFID Reader Module with Raspberry Pi Pico

Overview

In this guide, we will interface the RFID Module RC522 with Raspberry Pi Pico & RGB LED Module. Currently, the most popular RFID Module available in the Market is RC522 which is an SPI Module and operates at a frequency of 13.6MHz.

RFID (Radio Frequency Identification), also known as radio frequency identification, is a communication technology that can identify specific targets and read and write related data through radio signals without the need to establish mechanical or optical contact between the identification system and specific targets.

In this project, we will learn how to read RFID tag numbers from the RFID Reader by scanning RFID Cards. Later we will store the RFID numbers in the MicroPython Code to make an RFID Access Control System. If a registered and correct RFID tag number is found, the green/blue LED indicator will let you know. In case, if the wrong RFID is scanned, the Red LED will indicate the Card is not registered to a system disabling the Access.

Components Required

In this guide, I used Elecrow Raspberry Pi Pico Starter Kit to test different Modules. You can buy the kit and perform some other operations as well. From this kit, you can use the following components.

1. Raspberry Pi Pico Board – 1
2. RFID Module RC522 – 1
3. RFID Cards – 3
4. RGB LED Module – 1
5. Breadboard – 1
6. Jumper Wires – 4
7. Micro-USB Cable – 1

RFID RC522 Module

The RC522 RFID module based on the MFRC522 IC from NXP Semiconductor. It usually comes with an RFID card tag and a key tag. It has 1KB of memory and it is used to write a tag. Any message can be stored using this memory.

The RC522 RFID reader module is designed to create a 13.56MHz electromagnetic field and communicate with RFID tags. The reader can communicate with any microcontroller over a 4-pin SPI. In SPI Mode it can communicate with a maximum data rate of 10 Mbps. It also supports communication over I2C and UART protocols.

The RC522 RFID module can be programmed to generate an interrupt, allowing the module to alert us when a tag approaches it. The module’s operating voltage ranges from 2.5 to 3.3V, but its SPI Pin is 5V tolerant. Therefore you can connect the RC522 Module to Arduino or Raspberry Pi Pico.

Specifications

• Module interfaces SPI: Data transfer rate maximum 10 Mbit/s
• Power Voltage: 2.5-3.3 V
• Operating frequency: 13.56 MHz
• Operating current: 13-26 mA/DC 3.3 V
• Idle current: 10-13 mA/DC 3.3 V
• Sleep current: <80 uA
• Peak current: <30 mA
• Read Range: 0 ~ 35 mm (mifare1 card)
• Supported card types: Mifare1 S50, Mifare1 S70, MIFARE Ultralight, Mifare Pro, and MIFARE DESFire

RFID RC522 Pinout

The RFID RC522 communicates via SPI, I2C & UART Communication Mode. It has a total number of 9 pins.

• SDA SCL: I2C Communication pins. DATA and CLOCK.
• SS SCK MOSI MISO: SPI communication pins. Slave Select, Clock, MOSI, and MISO.
• RX TX: UART Communication pins.
• IRQ:  Interrupt signal from the module to indicate RFID tag detection.
• GND: Ground pin that needs to be connected to the GND pin on the Arduino.
• RST: Reset pin for the module
• VCC: Supply pin for the module (2.5V to 3.3V).

Interfacing RC522 RFID Reader Module with Raspberry Pi Pico

Now let us interface the RFID RC522 with Raspberry Pi Pico in SPI Mode. The connection diagram is fairly simple.

First connect the RFID RC522 Pins to Raspberry Pi Pico as follows.

Then connect the RGB LED Module R, G & B Pins to GP0, GP1 & GP2 of Raspberry Pi Pico.

MicroPython Code

We will be programming the Raspberry Pi Pico with MicroPython Code to communicate with RFID RC522 Module.

The code is divided into 3 parts as:
1. mfrc522.py which is the library for RC522 Module
2. data_read.py which is the code to read the RFID Tags
3. RGB_Control.py which is used to match the RFID Tag and control the RGB LED

mfrc522.py (RC522 Library)

Copy the following code and save it to Raspberry Pi Pico with the name mfrc522.py.

data_read.py (Reading the RFID Tag Number)

Copy the following code and save it to Raspberry Pi Pico with the name data_read.py. This is used to read the RFID Tag numbers.

Now run both of the above codes and you are ready to check the RFID Tag numbers. In my case, I will be reading the tag number of 3 RFID Cards.

Whenever the card is scanned, the RFID Tag number is displayed on Python Shell. You can copy and note down the RFID Tag number as it will be used in the next code.

RGB_Control.py (Comparision & Access Control System)

Since we read and copied the RFID Tag number in the above code, now using the following code, you can compare and make an Access Control System.

The two card numbers are stored in the following lines. You need to replace both the RFID Tag number with the tag number you copied.

Now you can copy the following code and save it to Raspberry Pi Pico with the name RGB_Control.py.

Run the mfrc522.py and the RGB_Control.py together.

After running, you can scan the RFID Cards now. When you scan the individual know RFID tags, the Blue LED & Green LED will turn ON according to the color assignment.

Whenever you scan an unknown RFID Card, the Red LED will turn on which means the Access Control is not allowed.

This is how you can interface the RFID Module RC522 with Raspberry Pi Pico. You can implement an RFID Access control System using the project.