Use an Arduino to Build a Complete Multi-Station RFID Security Check System

One of the first widespread uses of RFID (Radio-Frequency Identification) technology was for security systems, and that still remains one of the most popular applications. That’s because RFID chips don’t require a power source of their own and can be quickly read with just a tap, which means they’re convenient to use. But “real” commercial RFID security systems can be expensive. If you’re willing to take a DIY approach, however, Giannis Vasilakis has a great tutorial on how to build one based on the Arduino Uno’s ATmega328P microcontroller.

Vasilakis’ design is intended for real-world security situations. Specifically, it’s a master-slave setup that is ideal for warehouses and other locations with many security guards and multiple security check points. One of the slave RFID readers can be placed in any location where a security check point is required. To pass through, a guard would need to scan their unique RFID card. The unique ID is then sent from the slave to the remote master device over an RS-485 data bus where it can be logged. The system supports up to 254 slave devices, so this setup can be used in a large building.

Both the master and slave devices run on the same ATmega328P microcontroller that is found in many Arduino boards. A custom PCB is required for each, but you could also use an actual Arduino with a breadboard if you just want to experiment with the system. Both devices use a MFRC-522 RFID module and a SN75176 RS485 transceiver. The slave devices also get a 16x2 character LCD to display the status after an RFID card swipe. 3D-printable enclosures are provided for both, as well as the code to make it all work. After setup, a computer connected to the master device can be used to pull reports of the RFID scan logs.