MFRC522 RFID Module

Part images

What it is

The MFRC522 module reads and writes 13.56 MHz contactless RFID/NFC-style cards and tags.

How students use it

Students use it for badge unlocks, project passports, music triggers, inventory ideas, and security-themed demos.

Pins and power

Typical MFRC522 modules expose 3.3V, GND, RST, SDA/CS, SCK, MOSI, MISO, and sometimes IRQ. Verify labels on the actual board.

Use 3.3V module power and 3.3V logic with the Pico. Do not assume a 5V RFID module is GPIO-safe.

SunFounder describes the MFRC522 chip as supporting SPI, I2C, or UART host interfaces; the common Pico lesson wiring uses SPI-style pins.

Voltage and safety

Keep power and logic at 3.3V. The antenna is RF hardware; do not modify it while powered.

Treat RFID demos as learning projects, not real access control. Do not store private data or depend on simple UID checks for security.

Module internals

Main component: NXP MFRC522 contactless reader/writer IC.

MFRC522 IC, PCB antenna coil, crystal/clock parts, SPI header pins, reset/chip-select lines, support passives, and included RFID card/tag.

Datasheet notes

SunFounder identifies the MFRC522 as an NXP 13.56 MHz reader/writer IC supporting passive contactless communication, MIFARE products, CRYPTO1 authentication, and data rates up to 424 kbit/s.

Common libraries

Use machine.SPI plus a MicroPython MFRC522 driver. Lesson code should keep card UIDs and security limitations clear.

Common mistakes

Using 5V logic, mixing up SDA/CS with I2C SDA, forgetting RST or chip select, holding the tag too far from the antenna, and treating card UID checks as strong security.