This topic covers the interfacing of RFID system with microcontroller through serial interrupt. An RFID system consists of a reader device and a transponder. A transponder or tag has a unique serial number which is identified by the reader. RFID tag is applied to products, individuals or animals to identify and track them through this number.
The interfacing has been done through AT89C51. The identification code of the tag is also displayed on a 16x2 LCD. The free source code for the program is available in C.
The RFID system interfaced with AT89C51 requires the controller to continuously scan the input from the RFID reader. In this topic, the program has been made more efficient by incorporating a serial interrupt.
Different RFID tags work on different frequencies. Here low frequency, 125 kHz, RFID tags have been used. These tags work within a range of 10 cm. When an RFID tag comes in this range, the reader detects it and sends a unique code of the tag serially. This serial code, consisting of 12 bytes, is received by the microcontroller.
In the program, Timer1 is configured for serial communication. (Refer Timer programming in 8051) The baud rate is set to 9600bps for data transmission. The LCD is initialized to display the code. When a card/tag comes in the proximity of RFID reader, the microcontroller reads the code and sends it to the LCD module.