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Making electronic systems wearable is an increasingly popular design option. Advances in process technology and wireless protocols have enabled wearable electronics to be integrated into a wide range of form factors for many different applications, and this is just the start for the technology.
Two key factors have come together to enable this tremendous development. Firstly, the recent advances in process technology deliver lower power consumption and higher computing performance, allowing designers to trade off functionality and battery life. Secondly, a new generation of wireless protocols is able to provide standardised low power links from wearable systems to a smartphone. This avoids the need for a dedicated terminal in order to use the technology, and opens up wearable electronics to billions of smartphone users.
This move has not been lost on the world’s largest semiconductor maker, nor on world’s largest microprocessor ecosystem. Intel’s Edison platform is now bringing x86-based software to the wearable market, while hundreds of chipmakers are integrating processors with the 32bit ARM architecture into low power wearable designs.
The Bluetooth low energy (BLE) specification, now called Bluetooth Smart, starts with version 4.0 and builds on previous versions to allow a Bluetooth node to be both a peripheral and a controller, making it easier to set up reliable connections. Bluetooth Smart is also optimised for wearable applications with a short range and reduced data rate that greatly extends the battery life in the node. This means that the wearable system can communicate easily with a smartphone as both a controller and as a link to the Internet. This has led to a wide range of fitness tracers, smart watches and other wearable devices for monitoring health, from babies to adults. Sensors and controllers are also being integrated into gloves and other items of clothing to improve productivity at work.
But wearable technology is extending even further. Cameras are being integrated with transmission system in shirts worn by football players or even in wearable mini-drones that can take off from your shoulder in new ways of connecting people.
There are several platforms available for developing wearable systems, from ultra-low power 16bit controllers to the latest high performance 32bit systems.
Intel’s Edison board provides a dual-core, dual-threaded 500MHz Intel Atom CPU and 100MHz Intel Quark microcontroller with 1GB of low power DDR3 memory, 4GB of flash memory as well as WiFi and Bluetooth 4.0. With 40 configurable 1.8V GPIO lines and breakout boards to other platforms such as Arduino, the board can be used to develop a wide range of wearable applications using Yocto Linux v1.6 and a real time operating system.
The Intel Edison board combines a microcontroller and microprocessor for sophisticated wearable designs and Internet of Things Applications.
The 50mm diameter LilyPad Arduino is based around Atmel’s ATMega32u4 microcontroller and designed specifically for wearables and e-textiles as it can be sewn to fabric and similarly mounted power supplies, sensors and actuators with conductive thread. It has nine digital IO pins - four that can be used as PWM outputs and four as analogue inputs – as well as an 8MHz resonator, a micro USB connection, a JST connector for a 3.7V lightweight lithium polymer battery and a reset button. The built-in USB connection allows the board to appear as a mouse and keyboard, providing an easy way to send data back and forth.
The LilyPad Arduino board is designed to be sewn into clothing
For smart watch designs, Texas Instruments has developed a Bluetooth smart watch development system called Chronos. This combines the ez430 16bit microcontroller core in a single chip with wireless connections in the 868MHz unlicensed band for the EU and 915MHz band for the US. This allows the smart watch design to act as a central hub for nearby wireless sensors such as pedometers and heart rate monitors. It also integrates a 96-segment LCD display with a pressure sensor and three-axis accelerometer to allow developers to design their own innovative motion sensitive control algorithms.
Microcontrollers such as the EFM32LG Leopard Gecko from Silicon Labs have been designed for ultra-low power consumption, switching off parts of the chip when not in use and powering them up quickly when needed, and so are being designed into wearable designs. This family of devices combines a 32bit ARM Cortex-M3 core with a wide range of peripherals that can be mapped directly to the needs of the design and so provide the optimum balance of performance and power consumption.
Wearable technology has only just started to scratch the surface of potential applications. The Bluetooth Special Interest group is extending Bluetooth Smart to include a mesh protocol. This would allow devices around the body to easily connect up, creating an ultra low power personal area network (PAN) that can be easily controlled by a smartphone.
Advances in manufacturing technology are also promising to add new capabilities to wearable systems. Flexible, printed electronic substrates are reducing the weight of the systems and making them easier to embed in clothing. This can create a network of sensors and controllers all across the body that provide a wide range of new capabilities.
Image credit- RIT.edu.