NFC tag with extra connectivity powers richer user interfaces
The latter enables the chip to communicate with a microcontroller and power small electronics (such as LEDs) as it harvests energy from a reader such as an NFC-enabled smartphone.
An additional externally powered 64-byte SRAM memory buffer mapped into the memory allows a fast data transfer between the RF and I²C interfaces and vice versa, without the write cycle limitations of the EEPROM memory.
Practically, this means that the NTAG I2C can exchange data over the air (from the NFC tag’s memory to the reader), but also over its I²C interface with the electronic appliance it is embedded in.
This could be for zero power configuration, where a reader could be used to configure any consumer electronics or home appliances even after manufacture, to perform late customisation, such as setting up the language or various options.
Embedded into the casing, such a dual interface NFC tag could be used to enrich user interfaces of low-cost white goods featuring very small monochromatic screens (while the premium category may run full colour touch-screens).
In one of the demos put forward by NXP, a smartphone is used to retrieve the operating menu from a washing machine and get a much richer touch-based interface on the user’s smartphone.
The user can configure the washing cycles and program the machine to run according to his/her preferences, through an intuitive interface, then feed the data back to the NFC tag which will pass it on to the microcontroller for reconfiguration through its I²C interface.
In another case scenario, say when there is a malfunction, the user could pick up all the diagnostics and service history of the machine by simply tapping an NFC-enabled smartphone onto the interface pad, then directly access online help to fix the issue. Alternatively, this information could be passed on to a remote technician via a cloud service.
Even with the appliance unplugged, the technician may figure out what the problem is and perform a firmware update, first downloaded to the user’s smartphone, then transferred to the appliance through the NFC chip to the microcontroller (powered by energy harvesting from the coil antenna as the reader is in proximity).
The NTAG I2C measures 1.6 x 1.6 x 0.6 mm in a quad flat package, with either 1k or 2k of user memory (of course this memory is not a limiting factor since data can be transferred directly to the appliance’s onboard memory).
EnOcean’s energy harvesting switch study also demonstrated in Nuremberg was relying on this NFC tag for configuring the switch’s modes and functionalities during installation. This allows the installer to use the ser interface of an NFC-enabled phone (the switch having none).