Here’s a complete example of how to trigger a relay using RFID-RC522 and Arduino Nano when a specific RFID card is detected.Hardware NeededArduino NanoRFID-RC522 module (MFRC522)Relay module (5V)Jumper wiresRFID card/tagWiring DiagramRFID-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) |