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RFID
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Circuit knowledge
RFID
RFID (Radio Frequency Identification) is a wireless communication technology. A complete RFID system is
generally composed of the responder and reader. Generally, we use tags as responders, and each tag has a
unique code, which is attached to the object to identify the target object. The reader is a device for reading
(or writing) tag information.
Products derived from RFID technology can be divided into three categories: passive RFID products, active
RFID products and semi active RFID products. And Passive RFID products are the earliest, the most mature
and most widely used products in the market among others. It can be seen everywhere in our daily life such
as, the bus card, dining card, bank card, hotel access cards, etc., and all of these belong to close-range contact
recognition. The main operating frequency of Passive RFID products are: 125KHZ (low frequency), 13.56MHZ
(high frequency), 433MHZ (ultrahigh frequency), 915MHZ (ultrahigh frequency). Active and semi active RFID
products work at higher frequencies.
The RFID module we use is a passive RFID product with the operating frequency of 13.56MHz.
Component Knowledge
MFRC522 RFID Module
The MFRC522 is a highly integrated reader/writer IC for contactless communication at 13.56MHz.
The MFRC522's internal transmitter is able to drive a reader/writer antenna designed to communicate with
ISO/IEC 14443 A/MIFARE cards and transponders without additional active circuitry. The receiver module
provides a robust and efficient implementation for demodulating and decoding signals from ISO/IEC 14443
A/MIFARE compatible cards and transponders. The digital module manages the complete ISO/IEC 14443A
framing and error detection (parity and CRC) functionality.
This RFID Module uses MFRC522 as the control chip, and SPI (Peripheral Interface Serial) as the reserved
interface.
