Bluetooth SmartController powered by harvested energy

Operating from voltages as low as 0.8V, the EM9301 can be powered by a wide range of common single-cell batteries or energy harvesters such as solar cells, piezo-electric and electro-magnetic elements. Combining the Physical layer, Link layer and Host Controller Interface layer in one flexible chip, the EM9301 is fully Bluetooth Smart qualified for single-mode master and slave applications and is optimized for ultra-low power wireless sensing, remote control and monitoring applications.

When paired with a low-power host controller, the EM9301 comprises a cost/performance/size optimized solution for most Bluetooth Smart applications such as wireless health and fitness monitoring, electronic leashes, and smartphone-based sensing and controls.

Powered by a variety of photovoltaic solar cells, the EM9301 and an EM6819 ULP 8-bit Flash microcontroller can send sensor data, such as temperature, light level and beacon/location information to an application running on nearby smartphones using Bluetooth low energy technology.

These 'emBeacons' have been tested and perform consistently well under real-world conditions such as indoor lighting, periods of darkness, cold startup, etc. With the 'emBeacon' consuming only 150 microjoules per beacon event, nominally occurring every 5 seconds, the operating lifetime is extended while the size and cost of the zinc-air capacity or energy harvester is minimised. Power consumption is only 200 µJ for supply voltages less than 1.8V, this figure includes ALL power consumed during sleep, wake up, calibration, sensor measurement, and wireless communications.

Michel Willemin, EM Chief Executive Officer and general manager, commented: “EM developed a similar beacon design this past summer, intended for use with a 1V LR44 or AAA alkaline battery, but we knew that we could and should drive the power consumption down even further and provide a more ecologically friendly solution to our customers. The excitement surrounding Bluetooth Smart beacon technology clearly confirmed what we started to develop a few years ago and suggests a strong market need for a cost-effective, green and completely untethered beacon hardware platform. EM is proud to offer green beacon solutions based on Bluetooth low energy technology with an attractive price and best in class power consumption profile.”

With a low average power consumption of just 5µA, the 'emBeacon' is projected to last more than one month on a BlueSpark 101-UT1 printed battery or over 2 ½ years on a Renata ZA675 zinc-air battery. In energy harvested systems, the 'emBeacon' can transmit in the dark for an hour on a one Farad supercapacitor or almost 2 days on a nine Faradsupercapacitor. However, these results are highly dependent upon the exact capacitor chosen.

Developed by KS Technologies, an EM technology partner, is the emBeacon iPhone application which searches for and displays a list of all 'emBeacon' devices within range. Once a device has been selected, the sensor data (temperature, light level, battery level, received signal strength and packets transmitted) is displayed on a screen dedicated to that particular 'emBeacon'. This beaconing technique allows all of the beacons within range to be visible to all the smartphones in the vicinity, so all beacons can be viewed simultaneously by multiple phones. This is in contrast to a 'connected' model, where beacons are 'paired' with a phone and then become invisible to other phones in the area.

Available in production quantities in both die format and in a ROHS-compliant MLF-24 package, purchase of the EM9301 includes a license-free Bluetooth Smart stack for 8051, ARM Cortex M0 or M3 cores. Numerous development kits for various microcontrollers are available. The emBeacon reference design, which contains a Bill of Materials, PCB gerber files, and demo firmware is available on EM’s website.