WRL-14131

Page 1 of 7 RFID Basics Introduction A few months ago I checked out a stack of books at our local library by placing the books on a kiosk. All 5 books magically appeared on the computer screen. Around the same time my father ran in the Bolder Boulder, a foot race of over 50,000 people. An electronic system kept track of his time and thousands of others by only having the runners wear paper race bibs. Pets that are found wandering can be identified and returned to their owners with a basic scan of the neck. How is all of this possible? Source: icons8 The answer is RFID or Radio Frequency IDentification. This tutorial will cover the basics of how RFID works, and will help guide you towards getting started with RFID. Suggested Reading If you aren’t familiar with the following concepts, check out these tutorials before continuing. They will help with the basic understanding of RFID. • The Basics of Binary • What is a Battery? • Electric Power Basics Basic Functionality It may be tempting to believe that RFID functions thanks to the reader module containing a very small hamster with x-ray eyes, but in actuality, the system is a bit simpler than that. Page 2 of 7 How RFID doesn’t work RFID uses radio waves produced by a reader to detect the presence of (then read the data stored on) an RFID tag. Tags are embedded in small items like cards, buttons, or tiny capsules. Image courtesy of EPC RFID These readers also use radio waves in some systems to write new information to the tags. Types of RFID Systems There are two types of RFID systems: passive or active. The tag power system defines which type of system it is. Passive In a passive RFID system, the tags do not use a battery; instead, they receive their energy to run from the reader. The reader emits an energy field of a few feet, providing the energy for any tag in the vicinity. The tag gathers the electromagnetic energy from the card reader, powers up, and responds with ‘hello world’ and its identification information. Passive tags have the benefit of being able to be read at a fast rate (10 or more times a second). They are extremely thin (allowing them to be placed between layers of paper) and are extremely cheap (less than $0.05 in 10,000+pcs volumes). Page 3 of 7 In general, the smaller the tag the much shorter the read range Active Active RFID systems include tags that have their own internal power supply for increased range. Active tags possess a battery and usually have larger SMD components. After a preset amount of time the tag emits an RF ‘chirp’. A reader in the vicinity can listen and hear for this chirp. Because an active tag is they can be read over much larger distances than passive tags (tens of feet). Downsides to active tags include greater bulk (because of the battery), limited life span (tag is dead when the battery is exhausted), increased cost per tag, and varying report rates. m130 Active RFID asset tag from RF Code RFID Frequencies As well as active and passive systems, RFID systems can also be broken out into different frequencies. Some frequencies and systems are designed to only read one tag at a time, while others can read multiple. Cost of readers can also vary wildly based the frequency rating of the modules. In prior years a reader capable of reading multiple tags was in the thousands of dollars, sometimes tens of thousands. These systems were unattainable for most hobbyists and prototypers. However, this is finally beginning to change, and multi-read capable readers are becoming much more affordable. Check out the following chart for a basic break down of the frequencies, and their associated properties. A Few Common RFID Reader Types Frequency AKA Range Read/Write Read Multiple Tags Simultaneously Average Tag Cost Page 4 of 7 Low Frequency (120-150 kHz) "Chips/microchips" (in veterinary applications), prox cards, HID cards (both trade names) Up to 20 cm/