by Michael Barger
Wireless devices are those that communicate with a greater electronic ecosystem through controlled intentional electromagnetic emissions, which are colloquially known as radio. Wireless technologies usher with them convenience and connectivity, unconstrained by cables, to make information more widely and immediately accessible and to automate more aspects of our lives and businesses than ever before.
Wired forms of connectivity such as Ethernet and USB are well recognized and established. Recently, wireless connectivity to the Internet through IEEE 802.11 (Wi-Fi); to nearby devices through Bluetooth (BT/BLE); or even nearer devices through NFC (Near-Field Communication) have become basic expectations for devices intended to be everywhere connected to the Internet or to fluidly interact with consumers’ smartphones and computers. In our brave new world, free, accurate outdoor positioning can be acquired by anyone by receiving and processing signals from the various international constellations of satellite navigation systems: GPS, GLONASS, Galileo and BeiDou.
Most consumers are familiar with these wireless protocols since they have been made universal through smartphone ubiquity. By facilitating wireless connectivity between one’s product and the user’s smartphone, one can take full advantage of that user’s preexisting investment to save on product BOM cost: using the phone’s expensive, high-quality touchscreen display, sensors and wireless interfaces, or off-loading heavy computation to the phone’s powerful processors.
Internet of Things (IoT) devices are an exciting, emerging market, seeking to ever enhance the connectedness of our increasingly digital world. While the IoT-specific wireless standards space is hotly competitive and fragmented, the goal of IoT remains universal: take information from a device’s immediate environment, transmit it wirelessly to an Internet connection, and then make that information available from anywhere via the Cloud; and conversely, to allow the transmission of information from the Internet back to those devices to provide remote control from anywhere on Earth. Beyond the consumer market, Industrial Internet of Things (IIoT) applications are just starting to take off, presenting factories, farms and offices new opportunities to automate or analyze metrics. IoT technologies enable us be in more than one place and do more than one thing at the same time.
Another major duty of a wireless device can be to connect with and relay information directly with its nearby user. Human-machine interfaces (HMIs) represent an array of I/O hardware intended to facilitate efficient and timely communication from human to device (or vice-versa) whether they be vivid touchscreen displays, speakers, LEDs, microphones, pushbuttons, or a gentle, nearly-silent haptic tap. Other wireless devices might take advantage of their connectivity to leverage users’ existing smartphone HMI, to minimize product BOM cost.
Battery-Powered Micro Devices
Nearly all wireless devices are also battery-powered devices: after all, what use is wireless communication if one must remain tethered during use? Some devices go even further to banish cables, introducing inductive wireless charging to remove charging ports entirely. The energy stored within a battery is precious, since it is finite and capacity comes with proportional costs: size, weight, unit price; power budgets must be drawn up and analyzed against use-case stories during architecture in order to right-size capacity, track leakage current, identify dominant power sinks, and maximize efficiency.
Wearables (wearable electronics) are a specific type of embedded technology that is almost always battery-powered and wireless. Energy harvesting techniques allow us to tap into ambient power sources such as the body movement or heat of the wearer, ambient light or RF energy to generate small amounts of electricity. Through this technology, we can allow a low-power wireless electronic device to function without any manual user intervention to ever charge or replace batteries, helping users avoid modern maladies such as “range anxiety” or “charging fatigue”.
With wearables in particular, there is much interest in minimizing the form factor of the electronics: here, SIGMADESIGN’s expertise in the design of High-Density Interconnect (HDI) PCBs is frequently exercised to increase component density and utilize smaller IC packages. Adoption of flex and rigid-flex PCB technologies can be critical to achieving compact form factors that conform to the contours of the human body. After all, wearables that are unfashionable, uncomfortable or physically interfere with movement will face increased resistance from potential wearers.
RF (Radio Frequency) Engineering is a crucial competency for the development of wireless devices: after all, what use is a connectivity-oriented device that cannot reliably communicate over far enough of a distance? Even for the simplest of wireless applications, the skilled selection or design of suitable antennas, transmission lines, filters and impedance-matching circuits are necessary to optimize product functionality and working range.
Many wireless products will demand custom antenna design: for example, for Bluetooth, it is generally more cost effective to implement a “chip-down” solution (that does not use pre-certified modules) once target volumes reach the thirty-thousand or so. The design of an antenna that meets range, cost, and form-factor needs, along with the tuning (impedance matching) of that antenna to accommodate the interactive effects of nearby inanimate and animate (in the case of wearables) capacitive elements, and finally expediently navigating the EMC certification process takes a specialized knowledge set.
Electromagnetic compatibility (EMC) is an important part of the compliance process because conformance with the respective standards of each country the product is marketed in are legal requirements that can carry severe penalties. While any digital electronic device needs to be designed to and tested for unintentional conducted and radiated electromagnetic emissions, the stricter, more time-consuming and costly intentional-emitter EMC testing and additional unique kinds of wireless certification that radios are subject to are oft-underestimated factors that can potentially impact Time to Market plans; having a design team at one’s disposal that is familiar with and can help avoid common roadblocks will prove to be a worthwhile investment.
A common theme among wireless devices is the central brain: the microcontroller. Microcontrollers, unlike applications-grade microprocessors, are optimized for minimal unit-cost and power consumption, along with the synchronous interfaces required to “talk” with other sensors and board-level components that are common in embedded systems. There now exist highly integrated System on Chip (SoC) solutions on the market that include one or more microcontroller cores, power and peripheral management functions, and wireless radio technology all on one silicon die, within a single package; this minimizes unit cost and overall size, both important design factors in consumer wearables.
Even more importantly, we maintain dedicated and capable Engineering teams to support all aspects of development: Firmware Engineers who can handle the programming for the embedded device; Software Engineers who can complete the Web, iOS or Android app, or Windows/Linux native connectivity; Mechanical Engineers, well-versed in wearable technology and electronic enclosures; and Systems Engineers who help drive interdisciplinary decisions toward system requirements. These Engineering disciplines, along with assembly and machine shops and test labs, all work together under one roof at SIGMADESIGN to take your wireless product from concept through production!