Winning design strategies for the wearables market

Raman Sharma, Silicon Labs

September 10, 2014

Raman Sharma, Silicon LabsSeptember 10, 2014

The advent of laptops in the 1990s, coinciding with the expansion of the Internet, freed us from the tethers of power cords and Ethernet cables. Then the explosive growth of cell phones and smartphones brought us unprecedented mobility and wireless connectivity. Today’s Wrist-top Revolution, coupled with the meteoric rise of the Internet of Things (IoT), is taking mobility to a whole new level: wearable computing.

In this article, we’ll examine the concepts behind the user-experience-driven design methodologies that are being used to create some of the most successful wearable products on the market. We’ll also consider the features and functions that drive a wearable product’s energy budget and computational requirements, including the selection of microcontrollers (MCUs) that meet the product’s design requirements.

New realities of the wrist-top revolution
Smart watches, activity trackers, wearable GPS devices, heart rate monitors and smart glasses are prime examples of the wearable products that generated an estimated $8 billion in global sales in 2013, according to Futuresource Consulting. Offering novel combinations of sophisticated functionality, easy-to-use connectivity, compact form factors, ultra-low-power processing, and wireless connectivity, wearable devices are giving rise to entirely new classes of personal electronics that help us stay healthier, better informed, and better equipped.

Although several leading smartphone manufacturers began experimenting with bulky wrist-top versions of their existing handset products several years ago, the wrist-top revolution kicked into high gear in early 2012 when innovative upstarts like the Pebble Smartwatch leapfrogged the smartphone makers with a new class of lightweight wrist-top devices that made it easier for end users to leverage the smartphones they already owned. Garmin, Samsung, Sony, Fitbit, Magellan (Figure 1), and other consumer electronics makers also joined the wrist-top revolution with their own smartwatches, activity trackers, and other wearable products.

Figure 1: The Magellan Echo smart sports watch leverages Silicon Labs’ EFM32 Gecko MCU to extend battery life up to 11 months using a single CR2032 coin-cell battery.

This market environment has encouraged the emergence of small, agile startups whose innovative products, such as the Misfit Shine fitness tracker (Figure 2), are successfully competing for market share with established players.

Figure 2: The Misfit Shine is an elegantly designed fitness tracker that achieves exceptional energy efficiency and long battery life with the EFM32 Gecko MCU.

A successful wearable device must deliver the right combination of price, performance, functionality, and battery life, as well as a unique look, feel, and behavior to differentiate itself from its competitors. MCUs, sensors, wireless electronics, and attractive user interfaces must be shoehorned into a small footprint that can be comfortably worn on the wrist or elsewhere on one’s body. Since such form-factor constraints leave little room for a battery, wearable systems must be extremely energy-efficient to achieve the longest possible operating periods between battery replacements or charges.

User experience drives winning designs
Integrating these diverse elements into a market-winning product requires complex design trade-offs to balance power, performance, functionality, and form factor. Several manufacturers have successfully navigated this new territory using a so-called “user experience-driven” design methodology that inverts many of the conventional priorities and practices used by embedded developers.

The design process for an embedded system typically begins with defining the functions and capabilities that will serve as the project’s top-level drivers. Conversely, designing a wearable product frequently begins with defining the ‘user experience it’ will need to produce. These requirements define a product by the way it looks, feels, and interacts with the end user, as well as the impressions, feelings, and emotions it evokes. The next step in this design process is to translate the user experience into a ‘use case’, a set of top-level functional requirements used to define the product’s hardware and software elements.

Apple was one of the early pioneers of this strategy. They used it with great success to define new markets and capture existing ones. If you have any doubts about the importance of a well-crafted user experience, consider how the Apple iPod’s unique control wheel, jewel-like case designs, and easy-to-use iTunes software helped the company transform and eventually dominate the digital music player market.

Defining the user experience
The requirements that define a wearable product’s user experience fall into two categories:
  • Functionality – the unique look, feel, features and functions that differentiate a wearable product.
  • Ease of use – a set of requirements that enables easy set-up, intuitive operation and minimal maintenance. Long battery life plays an important role in ease of use since having to recharge a wearable device every few days can be frustrating and cause users to abandon the product.

Together, these elements define a user experience that can be translated easily into a use case forming the foundation of a product’s design. Depending on the application, defining the user experience might involve designing a wearable case that has an inviting texture, ergonomic shape, and design elements that convey a specific feeling. Other products might require creation of special visual paradigms for controls and displays that make complex operations simple and intuitive.

Defining the use case
Once a product’s user experience has been clearly defined, it must then be translated into a use case whose functional requirements will drive the wearable product’s design. A detailed use case can provide important information that makes it easier to perform accurate trade-off studies for nearly every aspect of a wearable design.

A use case should include the tasks the wearable device is expected to perform, the required resources, and the conditions in which it is expected to operate. These details typically include the types of data the device will collect, how it will interact with users and other devices, anticipated operating environment (temperature, water resistance, impact resistance, etc.), operational modes (data collection and analysis, user interactions, communication, etc.), and how frequently it synchronizes with other devices.

Armed with these guidelines, the design team can start to identify the sensing, computing, and communication components that best meet the application’s requirements. Meanwhile, the bill of materials (BOM) cost and energy budgets are developed in parallel with the preliminary design requirements, giving the team the necessary parameters to converge on an optimal design approach.

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