MFRC522 is an Arduino library that enables reading and writing RFID cards using RC522-based reader modules connected via SPI interface.
The library solves the problem of communicating with RFID cards from Arduino microcontrollers. It provides functions to interact with MIFARE Classic cards and compatible variants through the MFRC522 reader chip, handling the low-level SPI protocol and cryptographic communication required for card access. The library also includes utilities for managing chip select pins and performing firmware self-checks on the reader module.
The tool suits hobbyists and embedded systems developers building RFID-based access control, identification, or inventory systems with Arduino boards and RC522 modules. However, potential adopters should be aware that hardware quality varies significantly across suppliers, and the README recommends purchasing multiple devices from different sources to increase the likelihood of receiving functional boards. The library works fully with MIFARE Classic cards in 1k and 4k variants, works partially with MIFARE Ultralight and some other card types, and has limitations with multiple reader modules without additional multiplexing hardware. For advanced development needs, the README directs users toward the RFID_MFRC522v2 library as an alternative.
Development of the library by its original owner has ended and the project is in feature freeze, accepting only bug fixes, typo corrections, and documentation updates. The maintenance status is sporadic, and no extensions for additional boards or new examples are being added. This freeze was implemented to avoid breaking existing projects that depend on the library without documenting their version requirements.
