India's Innoviti connects watches to wireless data

Bangalore start-up Innoviti Embedded Solutions has developed a two-chip, wireless product (picture) that enables wrist watches to receive personalized messages and news feeds. One chip performs the RF-reception tasks, and the second controls other functions, including timekeeping, power management, and display.

The RF chip operates in the FM band of 88 to 108 MHz and uses the excess bandwidth available in commercial FM-radio-transmission streams to send data as a subcarrier. This approach enables data to coexist with the radio transmission and allows radio stations to use their infrastructure to provide value-added services. The company based the controller chip on an 8051 core, and the device has a two-cycle execution with power-efficient modes.

The main challenges in designing the product were controlling power consumption and cramming the package into a small profile to fit into a typical watch case. Because RF reception usually results in high power consumption, the designers implemented reception in time slots that synchronize with the transmitting server to cut power demand. The watch uses an OLED (organic-LED) display in place of more common LCDs to reduce power consumption. OLEDs are power-efficient and slim, and they provide high visibility, even in low-lighting conditions.

The size constraint for the design was less than 6 mm for the combined electronics, display, and battery. "One of the toughest challenges in the entire design was the antenna design. At 100 MHz, the wavelength is 3m, so an efficient antenna design would require at least 75m3 of space," says Ashok Baragi, Innoviti's vice president of engineering. "We had to figure out how to use the watch's internal mechanical features to create an antenna."

For power, the watch uses a lithium-ion battery because it provides a high capacity in a small form factor. However, watch manufacturers may switch to lithium-polymer varieties because manufacturers can fabricate them in different shapes to cater to various watch profiles.

Sophisticated built-in software enables the watch to perform its data-reception tricks. The challenge was to abstract the software architecture from the hardware interfaces to provide for easy layering—without adversely affecting power consumption. A lean core kernel with a simple scheduler manages the hardware interfaces. The scheduler synchronizes with the transmitter, which runs on an independent clock, using a network-timing reference that transmits to the receiver.

A leading watch manufacturer is currently evaluating Innoviti's design for commercialization but has not announced a schedule for public availability of a watch based on this technology.