In this tutorial, I go over how to integrate the EM-18 RFID Reader module with a Raspberry Pi board. I also show how to integrate an actuator, in this case an Relay, to respond to a correct reading from the RFID module. This actuator can be a solenoid lock, a speaker, or even a web interface that logs data.And also interface with a GSM module to give message notification. I discuss how this design can be implemented as an RFID smart lock.

Connecting the RFID to the Raspberry Pi

A simple RFID Communication System comprises of three parts: an RFID Card or Tag (which contains the user or product information embedded on a chip), an RFID Reader (a device which triggers the RFID card and extracts the information from the Card) and a Host System (like a Computer or a Microcontroller which then processes the data).

In this project, I will be using the popular EM-18 RFID Reader Module and a few RFID Cards. There is another popular RFID Reader called RFID RC522.

The main differences between EM-18 and RC522 RFID Modules are: EM-18 is based on 125 KHz Radio Frequency Communication while the RC522 is based on 13.56 MHz Frequency.Coming to the interface options, EM-18 uses Serial Communication whereas RC522 uses SPI Communication (although the chip supports I2C and UART as well).So, selection of the RFID Reader Module is very important as it defines how you communicate with the module using Raspberry Pi or Arduino.