| RFID is the abbreviation for Radio Frequency IDentification. It started out in the 1980’s purely as a contactless communication between a reader device and a transponder (tag), where the data exchanged between the two was simply a unique serial number (identification number) of the tag. It has since grown in complexity and functionality to incorporate bi-directional data transfer to and from the tag and the reader at different frequencies and using different communication protocols. |
| Passive RFID is where only the reader is powered and the transponder (tag) powers itself parasitically from the emitted radiation of the reader antenna. In passive Low Frequency (LF, 125 KHz- 150 KHz) RFID and passive High Frequency (HF, 13.56 MHz) RFID, the tag couples inductively to the magnetic field emitted by the reader and communicates with the reader by modulating the frequency of this magnetic field (Frequency Shift Keying, FSK). In UHF passive RFID, the electric field emitted by the reader antenna is used by the transponder (tag) to power itself and communication is achieved from the tag to the reader by backscatter. Active RFID is where both the reader and the transponder (tag) are powered. This is effectively low power radio with license free bands such as 433 MHz used. |
| There are 3 main frequency bands for RFID. LF is 125 – 150 kHz. HF is 13.56 MHz. UHF is 868 MHz – 960 MHz (depending upon the geographic region). Europe uses 865.6 – 867.6 MHz, North America uses 902-928 MHz, Australia 918-926 MHz and Japan uses 952-954 MHz. |
| NFC is based upon the communication used by HF RFID. The main difference being that an NFC device can operate in reader mode or tag emulation mode. An example of an NFC device is a smartphone or tablet when using it’s payment app such as Apple Wallet (IOS) or Google Pay (Android). An NFC device can operate in tag emulation mode to communicated with a HF RFID reader and can operate as a HF RFID reader to communicate with HF RFID transponders (tags). The software app on the NFC device will say whether it is operating as a reader or emulating a tag and it can be switched between the two modes of operation by the app. |
| LF and HF/ NFC devices are close proximity operating devices. The separation distance (range) that can be achieved between reader antenna and tag antenna depend upon several factors but is typically less than 15cm (6 inches) or 1X to 2X shortest antenna dimension, whichever is the lesser. Range is affected by the size of both the reader and transponder antennas (bigger = greater range), power output of the reader, angle between the reader antenna and the tag antenna (coplanar is best, perpendicular is worst), and electrically conductive materials (metal, carbon) being close to either antenna (located within 2 x antenna diameter/length from either antenna). Because the communication is very short range, HF/NFC devices are a very popular choice for secure transactions as it is practically impossible to eavesdrop and capture the communication between reader and tag and therefore fraudulently fool or scam such a system. In addition to this near impossibility at grabbing the communication, data exchange can be encrypted and access to tag data can require encryption keys to unlock them. UHF passive RFID devices can operate over much greater distances than LF or HF devices (up to 100 times greater distances). So, several metres and typically 5 metres to 20 metres. Operating range again is greatly influenced by the same factors as HF and LF devices, but with the addition that UHF RFID does not pass well through liquids such as water and this includes living tissue as it is mostly comprised of water. UHF requires much higher power than LF/HF/NFC systems. You don’t get something for nothing when it comes to energy transfer and communication range. |
| An RFID tag can be chosen to have both read only memory and read/write memory. This means configuration and system parameters can be stored dynamically on the tag by the reader in a user’s application. Barcodes are read only and can only store a small amount of fixed data, such as a website address or a serial/ stock number. RFID tags do not require clear line of sight whereas a barcode does. So, RFID tags can be read through material such as cardboard, paper, wood, plastics, whereas barcodes can’t. RFID tags are much more durable against mechanical damage than barcodes. Data storage and communication with an RFID tag can be encrypted for security, whereas it can’t with a barcode. |
| The choice of RFID tag depends upon what you want to use it for. Read only tags are fixed in terms of their data content such as unique serial number for identification, and data put into the tag by the issuer that is then set to read only so that it can’t be edited in future. They come in many form-factors (outer package options), such as labels, cards, key fobs, wristbands, injectable, tie attached, and custom packages such as mount-on metal (MoM). Read/write tags come in many forms and operating frequencies, communication interfaces, memory sizes, and level of data content access security (encryption). Choices of tag in LF and UHF are quite limited with mainly unique ID and sometimes small amounts of user read/write memory available. HF tags (13.56MHz) come in a much wider range of options with different interface protocols, amounts of EEPROM (flash) memory, and levels of access security (encryption) available. Eccel can provide all ranges of tag technology in standard packages and in custom packages with custom programming and printing options available on request. Tags can range in price from under US$0.20 in high quantity, to up to ~ $3 for very high memory/ high encryption tags in complex packaging and low quantities. |
| Eccel offer both wireless interface options (Wi-Fi and WPAN – BR/EDR + LE) and wired options (UART/Serial, USB, RS232, RS485, Ethernet). On our wireless interface devices wired interfaces are also offered as per the above list. So, if you wish to use our Pepper C1 or Jalapeño range of devices that offer wireless interfaces, you can also use a wired interface and in fact disable wireless interface if you have any concerns about security or power consumption or both. |
User applications require different form-factor/size and mounting options of RFID/NFC reader writer device. Eccel offer common device families in different form factors to accommodate this requirement:
These are ideal for applications where available space is an absolute premium and integration with the user’s other electronics on a common PCB is desired. They come with wireless (Wi-Fi/ WPAN – BR/EDR+ LE) and UART/Serial user host system interfaces. Again wireless can be fully disabled if required. They are our lowest cost form-factor.
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| Many applications have surroundings that interfere with RF radiation. Environments such as nearby electrical conductor materials such as metal and carbon-based materials can at worst totally block RF radiation, or at least partially absorb (attenuate) the RF signal and act to shift the frequency of the transmission output of the RF signal emitted from the reader. Custom tuning can mitigate this problem in many such RF hostile environments and achieve a satisfactory and robustly functioning system. Eccel have great expertise in achieving such solutions in many hostile RF environments and offer this service with our readers and tags. |
| In many user requirement applications, there may well be a very good solution provided by one of our standard hardware and firmware read/write modules and standard RFID transponders “off the shelf”. However, in many application scenarios some degree of customisation may be required to achieve an optimal product for the customer. This could be modified firmware or host system interface, modified external device connectivity and control, modified form-factor, custom enclosures, custom transponder packaging, custom printing etc. Eccel have great expertise and experience in providing such solutions at very low cost and fast turnaround. |