he Mifare RC522 RFID Module (13.56 MHz) is a popular, low-cost RFID reader/writer module used in access control, attendance systems, and Arduino/ESP32/Raspberry Pi projects. 🔹 Key Specifications Operating Frequency: 13.56 MHz (works with ISO14443A/MIFARE tags & cards) Communication Interface: SPI (default), also supports I²C and UART (requires reconfiguration) Operating Voltage: 2.5V – 3.3V (logic is 3.3V; some boards include level shifters for 5V tolerance) Current Consumption: ~13–26 mA while reading Reading Range: ~2–6 cm (depends on antenna size, tag type, and environment) Supported Tags: MIFARE 1K, 4K, Ultralight, DESFire, and other ISO14443A cards/fobs Chip: NXP MFRC522 🔹 Pin Configuration (Typical RC522 Board) Pin Description VCC 3.3V power supply RST Reset pin GND Ground IRQ Interrupt pin (optional, often unused) MISO Master In Slave Out (SPI data) MOSI Master Out Slave In (SPI data) SCK SPI clock SDA (NSS) SPI chip select (slave select) 🔹 Working Principle The module generates a 13.56 MHz RF field via its onboard antenna. When a compatible RFID tag/card enters this field, the chip powers the tag wirelessly and exchanges data. Data is transferred through SPI (most common with Arduino), I²C, or UART to the microcontroller. The system can then read/write tag data (depending on the tag type). 🔹 Applications Access Control Systems (doors, lockers, gates) Attendance Systems (schools, offices) Cashless Payment / Smart Card Projects Inventory and Asset Tracking IoT Authentication Projects (Arduino/Raspberry Pi/ESP32)