Embedded Lab

RFID is a technology that uses radio waves for transmitting the identity (unique serial number) of an object or a person. If you have an electronic key to access your office building, it probably uses the same technology. An RFID system has a reader and a transponder (also called tag). The reader transmits electromagnectic waves in its surrounding through an antenna system, and when a tag passes passes through the zone, it is activated and the reader can read the identification data stored inside the electronic tag. RFID tags could be passive (no power source) or active (battery operated). EngineersGarage has posted a tutorial on interfacing a passive RFID system with an AT89C51 microcontroller. The microcontroller reads the unique identification number inside the tag and displays on a standard character LCD.