For video reference : https://www.linkedin.com/posts/anubrata-shil-348a75208_embeddedsystems-rfid-fresher-activity-7099094588392427520-RaaV?utm_source=share&utm_medium=member_desktop
Radio-Frequency Identification( RFID) , is a technology that uses wireless communication to identify and track objects, people, or animals. It typically involves small RFID tags or chips that contain information and can be attached to or embedded in various items. These tags can be read and tracked using RFID readers , which emit radio waves to communicate with the tags and retrieve data from them.
There are generally three types of tags: 1.Active tags- They have their own power supply for keeping the tag ON and sending feedback signal to RFID reader. They have high range but because of the bulky size they are generally not mostly used . 2.Semi passive tags- Have their own power source but in order to transmit data they use the RFID reader's frequency as a power supply. Range- medium. 3. Passive tags - Don't have their own power supply uses reader module's frequency to transmit data.
WORKING OF RFID :
1.Supplying power to tag: When the RFID reader emits radio waves, it generates an electromagnetic field.When the electromagnetic field generated by the signal generator present in reader comes into proximity with the passive RFID tag, it induces a small electrical current in the tag's antenna. This current activates the tag.
2.Data transmission : Once activated, the RFID tag sends back a response signal that contains its unique identifier that was stored in its memory. The tag modulates its antenna's impedance using it's internal switch to reflect some of the reader's energy back to it.
3.Reader Reception : The RFID reader detects the reflected signal from the tag. By analyzing the variations in the reflected signal's frequency, amplitude, or phase, the reader decodes the data stored in the tag. The reader then processes the received data to extract the information stored in the tag, such as the tag's unique identification number or any other data that may be encoded on the tag.This data is then transmitted to MC using UART.
Note: A RFID reader of certain operational frequency can not be used to read tags of all frequency due to difference in their wavelength of operational signal.