In this project tutorial, you will use the multiple MFRC522 to control a solenoid lock and three LEDs. The MFRC522 uses Radio Frequency Identification (RFID). RFID uses electromagnetic fields to identify and track tags attached to an object. These tags contain electronically stored information. If the tag is placed in front of the reader the reader reads the tags. A benefit of RFID is that it does not require to be in the line of sight of the reader. In other words, you can attach the reader behind the material and it will still read the tag. The distance with cheaper readers is around 5cm. So if the tag is placed within that distance the reader will read the tag. In this tutorial, you will learn how to connect two mfrc522 readers to an Arduino Uno and detect if the tags are placed at the right reader.
The RFID-RC522 module is an RFID reader, which can read RFID tags in close-range. In order to read an RFID tag, the reader and the tag must have the same frequency. The RFID-RC522 module reads only High-frequency tags at 13.56 MHz. The voltage that the MFRC522 can handle is 3.3V. So, be cautious when you connect a power line from the breadboard to it. The reader can read tags from a maximum distance of 5cm.