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Beefing up wearables with Bluetooth Smart

13 Aug 2014  | Paul Williamson

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To provide a scalable platform, an additional microprocessor can be integrated in the solution with the additional processing power and expanded IO enabling more sensors (such as a barometric pressure sensor) and peripherals (like GPS to determine the current location) to be included in the product design. It also enables more complex data processing algorithms to be implemented and operating systems with a rich graphical interface to be used. The MCU interfaces to the CR101x device using a simple, standard control protocol over a serial bus.


Determining behaviour with profiles
Bluetooth Smart uses an asynchronous, Client-Server architecture. The server has data to be shared and it maintains the data elements, called 'attributes,' in a database. A client and server exchange data using attribute protocols.

The data present on the server is organised into services, in a service-oriented architecture. These can be discovered, interacted with and have a defined behaviour, which will always produce the same result given the same pre-conditions. Services define the behaviour of a server but do not mandate the client's behaviour; it is the 'profiles' that do this.

Profiles are high-level definitions that define how services can be used to enable an application or use case and determine the behaviour of a client. The Bluetooth SIG defines mandates and lists all the services and profiles. A smart watch could use almost all the profiles listed by the SIG. Use cases for each profile are outlined below:

 • Alert Notification Profile – connects to a smartphone and alert the user of calls, texts and emails. It may not display the full text of a message, but it will show details on the caller/sender's ID
 • Blood Pressure Profile – obtains blood pressure measurement and other data from a non-invasive blood pressure sensor
 • Cycling Speed and Cadence Profile – projects cycling speed and crank revolutions using a cycling speed and cadence sensor
 • Find Me Profile – triggers an alert on a misplaced peer device, for example a smartphone or a key-fob
 • Glucose Profile – obtains glucose measurement and other data from a glucose sensor
 • Heart Rate Profile – obtains data from a heart-rate sensor
 • Phone Alert Status Profile – controls ringer settings and alert status of a smartphone
 • Proximity Profile – defines behaviour when the watch moves away or comes close to a peer device, causing an alert. The alert may be used to take further action, for example lights automatically switching on as soon as a person enters the house or an alarm when a child strays far away from a parent
 • Running Speed And Cadence Profile – connects to a running speed and cadence Sensor to get instantaneous speed, cadence and stride length
 • Time Profile – obtains the date and time and related information such as time zone and daylight savings time from a peer device. This would be a special use-case not applicable to a wrist watch in which a house has a clock and other time-pieces that will display date and time without actually having the actual RTC
In the release of iOS7, Apple added a service to interact with the Apple notification centre (ANCS). This enables the smart watch to alert the user to any event that would be displayed in the 'swipe down' menu within iOS. The user can enable alerts from any app running on their iOS7 device to be alerted via their smartphone.

Further, Apple also introduced the iBeacon, a Bluetooth Smart-powered indoor positioning system, which many smart device developers are currently looking to capitalise on. With a wearable device that can communicate with iBeacons, a user or developer can not only receive alerts, but also improve interactions with their environment via contextual location awareness.

Taking the potential of Bluetooth Smart a step further, recent advancements in Bluetooth Smart mesh networks, such as CSRmesh, have shown that a user could theoretically control all of their Bluetooth Smart devices within range from a single Bluetooth Smart-enabled device. This means that a user can tap an icon on a smart watch and control a building's lighting, security or networked audio systems.


The Bluetooth Smart market has now tipped
In the next year, industry analysts expect to see a plethora of smart watches and other wearable devices enter the market. The recent enhancements to iOS 7 that enable enhanced support for smart watches coupled with support in Android, from 4.3 Jelly Bean onward, mean that Bluetooth Smart will be central to making these new types of electronic products of real value to the consumer.


About the author
Paul is responsible for CSR's market leading Health and Fitness WearableµEnergy products providing low energy connectivity solutions, including Bluetooth Smart, to a broad range of consumer smartphone and tablet accessories.


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