Introduction to Programming for RFIDs


RFID stands for Radio Frequency Identification. It is a form of wireless technology that uses radio waves to uniquely identify an object. It usually consists of a tag, a reader, and an antenna.  In this post I’ll introduce you to RFID technology and some of the interesting things that you can do with them as a programmer. 

Types of RFIDS

There are three main types of RFIDs:

  • LF: Low-Frequency band 
    • General Frequency Range: 30-300 kHz
    • Read Range: Contact-10cm
    • Applications: Animal tracking, access control, car key-fob, applications with high volumes of liquids and metals
  • HF: High-Frequency band
    • Primary Frequency Range: 13.56 MHz
    • Read Range: Near Contact- 30cm
    • Applications: DVD Kiosks, Library books, personal ID cards, poker/gaming chips, NFC applications
  • UHF: Ultra High Frequency Band (most powerful)
    • General Frequency Range: 300-3000 MHz
    • Read Range: 30-100+ meters
    • Applications: Vehicle tracking, auto manufacturing, mining, construction, asset tracking

Components of the RFID System

The components of the RFID system include the following: 

RFID Reader: The reader is the central hub of the system. It is the device that transmits and receives radio waves to communicate with the RFID tags. 

There are two types of reader: a fixed (stationary) reader or a mobile (handheld) reader. The fixed reader is generally more powerful because it has more ports for antennas, so it can read more tags. I like to compare RFID readers to the self-checkout counter at a store. The fixed reader is represented by the actual kiosk, where you can scan your items, weigh produce, find items, and pay. The mobile reader is represented by the handheld scanner that you can take around your cart to scan your bulkier items. While both serve a similar function, they do so in very different ways. 

RFID Antenna: The antenna converts the RFID reader’s signal into signals that can be picked up by the RFID tags. 

RFID Tags: Tags consist of an integrated circuit for storing the tag’s ID and other information, and an antenna for sending and receiving the signal. They come in different shapes and sizes, and can be stickers, cards, keychain fobs, or other similar devices. 

There are three types of RFID tags:

  • Active Tag: Active tags only operate in the ultra high frequency range. They have their own power source, which allows the tags to be read at larger distances and to continuously send out signals to readers. 
  • Passive Tag: Passive tags can operate in all frequencies (low, high, or ultra high). They receive energy from the radio waves generated by the reader, which then flows through the integrated circuit in the tag, activates the chip, and sends back the signal with the data to the reader. 
  • Semi-passive Tag: Semi-passive tags are the least common. They are a mix of active and passive tags. Semi-passive tags have a battery that runs the circuitry while communication is powered by the RFID reader.  

Examples of RFID Systems

Some common uses for RFID tags include: 

  • Race Timing: Marathons and other bigger races will typically place RFID tags in the numbers that runners pin to their chests. RFID readers at the starting line and finish line of the race can then easily mark the times of each runner.  
  • Inventory Tracking: Placing RFID tags on inventory allows stores to track products through the entire supply chain and easily keep track of inventory numbers and location. 
  • Access Control: Apartments, office buildings, clubs, and other spaces can use RFIDs to manage access to buildings. For example, my apartment complex uses a system called Latch. I have a card with an RFID tag for my apartment that I tap against a scanner to automatically open my door.  
  • Toll Collection: RFID readers at toll booths read the RFID tag in your car as you drive past. 
  • Shopping: Card readers at retailers are RFID readers that actually read the RFID tag in your card when you tap to pay. 
  • Vehicle Tracking: Similar to toll collection, the RFID tag in your vehicle makes it easy to track your vehicle location as you pass RFID readers. 
  • Attendance Tracking: RFIDs can be utilized for traffic control or to analyze crowd movement. For example, let’s say there is an event at a museum. If each patron is given an RFID tag at the door, RFID readers placed at the exhibits can help the museum monitor which exhibits receive the most traffic and which receive the least. 

Security and Privacy 

The biggest downside to RFIDs is their security. Since RFID tags typically only have one function, which is sending their unique ID to the RFID reader, RFID tag data can be easily read by someone with a compatible reader. 

Most RFID tags do not have the power to compute, meaning they are also incapable of utilizing an authentication system. The only exception is the tags used in passports. Passports have BAC (Basic Access Control). With BAC, the chip in the RFID tag is able to decode an encrypted token from the reader to verify the identity of the owner of the chip.  

To see more unique applications for RFIDs, check out Unmanned Grocery Stores on the Grio blog.   

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