The MFRC522 is an RF Module that consists of an RFID reader, RFID card and a key chain. The module operates 13.56MHz and supports 3 types of interfaces: SPI, UART and I2C. For example using I2C interface will allow you to connect plenty of RFID devices on just 2 wires. The module has a small size which is very useful for different ways of the device application. It can be easily integrated into various devices, bags, clothes, keys, luggage, advertising products and so on. The module operates at 3.3V as well as at 5V so hence commonly used in both designs. It is normally used in an application where a certain person/object has to be identified with a unique ID. The keychain has 1kB memory in it which can be used to stored unique data. The MFRC522 reader module can both read and write data into these memory elements. The reader can read data only form passive tags that operate on 13.56MHz. A serial peripheral interface (SPI compatible) is supported to enable high-speed communication to the host. The interface can handle data speeds up to 10 Mbit/s. When communicating with a host, the MFRC522 acts as a slave, receiving data from the external host for register settings, sending and receiving data relevant for RF interface communication. An interface compatible with SPI enables high-speed serial communication between the MFRC522 and a microcontroller. The implemented interface is in accordance with the SPI standard.