Hundreds of millions of dollars have been spent on the R&D effort to develop passive RFID tags that can be offered for five cents or less. Have we succeeded? Almost. In high volumes assembled UHF tag inlays cost somewhere between seven and ten cents. Along the way, however, the RFID industry have invented something far more important: five-cent wireless networking!
What is it and how does it work?
Both NXP and Impinj have released RFID chips that offer an Inter-Integrated Circuit (I2C) interface in addition to the Gen2 RFID interface. The new chips also include significantly more memory compared to previous generations of simple-passive RFID IC’s: NXP’s UCODE I2C offers 3.3kBit of EEPROM memory; Impinj’s Monza-X offers 2.1 to 8.2kBit of EEPROM memory.
Electronics manufacturers have been using I2C-enabled EEPROM memory chips for decades to store small amounts of data persistently, including configuration data or boot-loading information. As the main microprocessor of a device is powered up, it reads configuration information from the memory chip via the I2C interface.
The new generation of I2C-RFID chips will maintain this functionality, but offer more. The memory content can be accessed through the I2C interface and through wireless RFID interface using a standard UHF Gen2 RFID reader. Since the RFID chips can be used in passive mode, the EEPROM memory can be read and written to without powering the host device.
Why is it so cheap?
Fully assembled conventional RFID tags require the actual chip, an antenna substrate, and the conversion into a usable package. A relatively small percentage of the cost can be attributed to the chip itself. The biggest cost items are the handling, assembly and antenna substrates.
When I2C-RFID chips are placed on printed circuit boards, the antenna is etched into the board at virtually no additional cost. The assembly is part of the surface mount board assembly, i.e. it’s also virtually free. Hence the only real cost item is the IC itself. The I2C enabled RFID chips are more expensive than the regular passive RFID IC’s, however, most of that cost can be attributed to the large memory of the chips. Since I2C-RFID chips replace conventional EEPROM chips, the marginal cost of adding RFID and hence wireless networking amounts to a few cents.
What is it going to be used for?
Device manufacturers will include the I2C-RFID chips to store essential configuration, licensing, or product information persistently. Since the memory can be written to over the air, configuration or licensing information can be applied to the device using an RFID reader without turning on the device.
In manufacturing, the RFID chip can be used to identify and serialize the device (WIP tracking). Once manufactured, channel partners are able to configure devices in the warehouse or at the point of sale without taking them out of the box.
Post sales, the device’s host processor can log information on usage hours, failure modes, misuse, use of consumables etc. on the I2C-RFID chip. As the device is sent in for maintenance or repair, the information is available to the service center through the RFID interface. Once again, the device does not have to be tuned on to read out the information.
Intel announced recently that it has included an I2C-RFID chip with the reference design for its new Windows 8 tablet computer, making Intel and its OEM partners the biggest users of this new capability yet.
Why is this so important?
More and more of the objects we buy and use on a daily basis include electronic circuit boards to support and enhance basic functionality: Nowadays toys like to speak to their child owners, kitchen appliances can be programmed to turn on at arbitrary times, toothbrushes beep when its time to switch sides, and power saws shut off electronically when safety is compromised. Today, few of these devices are networked and few are RFID-enabled. The inclusion of the new I2C-RFID ships will enable both RF networking and RF identification. Almost overnight networking and identification of inexpensive everyday objects has become feasible and realistic.
We have long been waiting for the Internet of Things to become a reality. I think I2C-RFID chips will finally make it happen.
(Photo: Tom Hurst / RFID Journal)