Steps for executing the project***
- The UID of RFID Cards is fetched using the Tag Reading Program
- The UID of the RFID Tags observed in the serial monitor should be noted down
- The sketch for Arduino Uno checks for the authenticity of the RFID Tags
- The information about the card is sent to the ESP8266
- The ESP8266 publishes the data received on the serial port to the Adafruit IO cloud
- The data can be retrieved from the feed of Adafruit IO
Working Principle** Low Freq and High Freq RFID Tags: Inductive Coupling (Near Field Coupling)
Ultra High Freq RFID Tags: Electromagnetic coupling (Far Field Coupling)
Radio waves sent by RFID Reader serve 3 purposes:
- Induces power in passive RFID Tag
- Synchronization clock to tag
- Act as carrier for return data from tag
Near Field Coupling: ->Field generated by RFID Reader couples with antenna of RFID Tag ->Because of this mutual coupling voltage is induced across the coil of RFID Tag ->Some portion of this voltage is rectified and used as power supply for the mcu and memory elements ->Volatge induced in coil is also of particular frequency as RFID reader sends radio waves of particular frequency ->Now if we place a load across the coil the current will start flowing ->If we change impedence then current value will change too ->If we switch the load on and off the current will switch on and off too ->This switching of current also generates voltage in RFID Tag ->This is called load modulation ->If we switch the load on and off according to the data stored in the card then data can be read by Reader in the form of voltage