01Module overview
MFRC522 talks to MIFARE Classic 1K/4K cards. Range ~3 cm. Comes with a card and a keyfob.
02Wiring (Arduino UNO)
- SDA → D10, SCK → D13, MOSI → D11, MISO → D12.
- RST → D9.
- 3.3V power only — 5V damages it.
03Reading a UID
Install the MFRC522 library, run the DumpInfo example, and tap your card. The serial monitor prints the 4-byte UID — store it as your 'key'.
04Beyond UID
Each MIFARE block holds 16 bytes encrypted with two keys. You can store balance, name or punch-card data; just don't rely on it for serious security — Classic encryption is broken.
