RFID-RC522 → Arduino Nano (SPI)
| RC522 Pin | Arduino Nano Pin || --------- | ------------------- || SDA (SS) | D10 || SCK | D13 || MOSI | D11 || MISO | D12 || IRQ | Not connected || GND | GND || RST | D9 || 3.3V | 3.3V (IMPORTANT) |