RFID technology has been around for more than a decade, and its adoption and use continues to grow. Standards-development issues have hampered adoption in some applications, but the industry has largely worked through those problems. Makers of RFID transponders and ICs are now expanding the scope of target applications by adding memory and chip functionality and developing advanced devices that can be deployed in embedded systems that enable customization.
Organizations such as Walmart have broadly deployed RFID technology for consumer goods tracking and even the U.S. Armed Forces has used RFID to track assets. RFID adds great value beyond the traditional bar code. A bar code can identify generally what is within a package or on a pallet while RFID technology can provide more specific information and exact serial number data. Moreover, RFID tags and labels can be scanned across moderate distances - an important feature in warehousing and supply chain applications - and in bulk.
Types of RFID
The RFID landscape is broken into three primary areas. Low-frequency (LF) implementations in the 135 to 135-kHz range are used primarily in applications such as animal identification and auto-immobilization systems. The low frequency offers the advantage of working in tough environments – even under water – but it limits reader tag-read rates and the ability to read multiple tags concurrently.
High-frequency (HF) implementations at 13.56 MHz are frequently found in retail environments. In the clothing industry, each garment gets a tag that can be used to support inventory operations while items remain within packaging or on shelves. Other applications include tracking pharmaceuticals, ticket payments or embedded in passports. HF systems support high item read rates and a relatively short range under 1 meter.
Ultra-high-frequency (UHF) systems generally operate in the 840 to 960-kHz range. Different bands are available in different parts of the world, so tags are designed to work anywhere in the specified UHF band. There also are some specialty applications that use the 2.45-GHz band.
UHF applications are usually found in pallet and case tracking of what is called FMCG (Fast Moving Consumer Goods) such as soda. UHF is also used in toll collection and in applications where a tag is embedded in an electronic system or printed circuit board. UHF implementations can support communications in the 10-meter range and offer optimum support for fast read rates and reading many tags within a small area.
A number of RFID standards have been pursued globally by the International Organization for Standardization (ISO) and other organizations. At times, either the lack of standards or competing standards have hampered RFID developments. The good news is that standards have been adopted for the two most broadly-used applications: ISO/IEC 15693 and ISO/IEC 18000.
ISO/IEC 15693 defines the HF standard that is widely used for noncontact financial transactions. ISO/IEC 18000 defines the air interface and methodology behind item identification and management applications. This standard includes seven parts that define operations across many frequency bands with part 6 defining the bulk of UHF applications.
Not to say that the path to standardization has been easy. At one point a conflict was identified when the EPCglobal organization defined Electronic Product Code (EPC) formats that used a field in a tag that the ISO standard allocated differently. EPCgloblal is the joint venture between EAN International and the U.S. Uniform Code Council that had promulgated bar-code standards and sought to take the next step with RFID. Today the EPC Gen2 (EPCglobal UHF Class 1 Generation 2) standard is supported in ISO/IEC 18000.
Clearly RFID works well in item identification and tracking but needs to be supported by consistent standards for wider adoption.
Historically, RFID tag and label design have been driven from a cost perspective – making cheaper tags to support quicker adoption of the technology. In the retail environment, many tag suppliers exist simply to drive down the cost of tag development. In 2010, some UHF tags hit the $0.05 level in high volume. With prices stabilizing, the most important features of RFID today tend to be chip performance and RFID software functionalities.
NXP Semiconductors is one company taking advantage of the need for higher functioning RFID technologies. The company offers an extremely broad portfolio of RFID transponders and reader ICs covering most frequency bands and has recently launched the UCODE family of ultra high frequency smart label ICs.
Conforming to the EPCglobal Class1 Gen2 standard, UCODE devices address applications demanding long operating distances and high anti-collision rates, such as supply chain management and logistics. The UCODE family has been designed to support other complex applications as well, such as FMCG, electronic products, industrial production and quality control.
Because these complex applications are data-intense, NXP significantly expanded the amount of memory on its UCODE chips for storing Electronic Product Code (EPC) and user data. The G2iM and G2iM+ ICs both extend user memory to 640 bits (prior products had a maximum of 512 bits).
NXP also created more robust access and control mechanisms to partition or manage data. For example, consider an electronics manufacturing line. With UCODE, quality and assembly departments could get dedicated areas of user memory to store data. Moreover, data storage areas could be password protected with access restricted to the owner of the memory region.
The G2iM+ expands EPC memory from the requisite 128 bits to 448 bits. In item-tracking applications, the additional memory can be used to store product status information. The G2iM also adds support for theft deterrence and tag tamper detection. Such features enable deployment in secure asset tracking.
NXP has also added features to its high-speed ICODE ILT smart label IC product line to accelerate the read-rate supported by the tags. The latest ICODE ILT IC enables systems to read 700 tags per second – 11 times faster than earlier devices – with excellent reliability, even in dense tag populations and at fast conveyer-belt speeds. NXP anticipates new opportunities in applications from medical to casinos, where tags in chips will allow automatic counting.
Integrating RFID and I²C
In April 2011, NXP gave developers a whole new chip feature with its UCODE I²C chip. The UCODE I²C UHF chip (Figure 1) supports bidirectional communication between a wireless reader and the microprocessor via the I²C interface. It has 3,328 bits of EEPROM memory, which can be used to upload updates to the embedded microprocessor upon power up.
Figure 1: The UCODE I²C RFID chip from NXP allows commissioning or customization data to be stored in tag memory and loaded into a system at power up.
This communications functionality opens up many new possibilities for wireless data exchange, product provisioning and even security. For example, high-end consumer electronics are always at risk for theft within the supply chain. With the UCODE I²C UHF chip, the product could be disabled within the supply chain and then commissioned at the point of sale.
Retailers can also customize data on a device at the point of sale, even when the RFID tag is integrated into a consumer goods item, and packaged inside a box. Without opening any packaging or powering on the product, the retailer could customize chip data, or add customer information. Subsequently, when the device is powered on it is able to read any customized or commissioning data over the I²C interface to the chip.
Designers working with RFID technology may want to rely on modular products to implement the reader side of the application. For example, Skyetek offers RFID reader modules that span all of the frequency ranges used in RFID applications (Figure 2). The modular approach accelerates time-to-market and provides access to a proven host software stack relative to working at the reader IC level.
Figure 2: Skyetek’s M7 SkyeModule and development kit allows design teams to jumpstart projects that are based on the EPC Gen2 standard for RFID tags.
There are quite a few RFID development kits on the market that can jumpstart RFID projects. For example, NXP offers several kits. Skyetek also offers development kits for virtually all of its reader modules. The Skyetek development kit portfolio spans the RFID frequency-band options and the different standards for air interfaces and product codes. If you want to experiment with EPC Gen2 applications, Skyetek offers the M7 SkyeModule and development kit (Figure 2) for that specific application.
Innovative manufacturers are promoting new RFID technology features with every new device. When working with any RFID project, make sure to check for the latest features and functions designed for emerging and complex applications. Beyond asset identification and tracking, RFID might just optimize manufacturing efforts or provide a better experience to the end customer.