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Connectivity and Low Power in the IoT Era

We are well into the Internet of Things Era, and have reached the point where we (almost) take it for granted that so many objects that are part of everyday life – even objects we don’t traditionally consider to be all that technologically-based – include embedded systems that connect them to the world. EETimes has been running articles that address some of the challenges that designers are grappling with when they’re creating IoT apps.

Given that connectivity is the most fundamental attribute of the IoT, it’s not surprising that one of the key challenge arenas lies here.

In her article, How to Select Wireless SoCs for Your IoT Designs, Gina Roos notes that choosing the right SoC isn’t that simple. It’s not merely a matter of picking one that supports the right wireless protocols that can meet range, latency and throughput requirements. There are other factors that designers need to think about, tradeoffs that need to be made: battery life, compute and memory resources, footprint.

First off, the application dictates what wireless protocol to use. Said Dhiraj Sogani of Silicon Labs:

“Every wireless protocol is playing a different role, and the end-application use cases are the most important in deciding one or more of these protocols for an IoT device.”…For wireless protocols, requirements include application throughput, latency, number of network nodes and range, he said. “IoT devices are becoming more complicated every day as more functionality is getting integrated into the devices. Adding wireless to the IoT devices increases the complexity manifold. There are many wireless protocols being used in IoT devices, including Wi-Fi, BT, BLE, Zigbee, Thread, Z-Wave and cellular. The choice of wireless communication protocols for a particular device depends upon the application, size, cost, power and several other factors.”

A wearable needs a different wireless protocol than a drone; a home security monitor has different requirements than a payment processing system. Form, in the form of wireless protocol, will definitely follow function.

There’s also the challenge of whether to use an integrated wireless SoC vs. separating out the wireless from the processor. Using an integrated SoC means a smaller footprint, and a smaller product. But it also means less flexibility when it comes to optimizing compute performance. It all depends. And, again, it comes down to the application. More complex applications may benefit from a discrete solution.

Other challenges that surround the choice of a wireless solution include RF circuitry, hardware longevity, and the software tools and environment (which will, of course, differ, depending on the OS selected). Lots to keep in mind!

And, of course, one of the things to keep in mind is power consumption. In his article, Energy Harvesting Circuit Enables Ultra-Low Power Apps, Maurizio Di Paolo Emilio takes on the topic from the lower end of the power consumption spectrum.

From the 10,000 foot perspective, he notes that the quest for “maximum efficiency” is common throughout the electronics sector:

Energy harvesting techniques can not only minimize—if not eliminate—maintenance interventions, but it can also reduce current consumption and minimization of power losses, enabling more efficient use of energy resources and the fulfillment of requirements imposed by recent global regulations.

But for ultra-low power apps, energy efficiency is closely tied to device feasibility, and much of this applies to the tens of billions of IoT devices in use.

In many cases, IoT devices are powered by rechargeable batteries that users must replace periodically.

By capturing and converting different forms of energy available in the environment, such as solar or wind power, it is possible to obtain the electrical energy required to recharge IoT device batteries. Other forms of usable energy are radio frequency (RF) signals, mechanical or kinetic energy, solar power, and thermal energy.

After briefly reviewing the most common energy harvesting sources, Emilio gets into energy harvesting circuit design and the need for “solutions that can make the most of the available energy, minimize losses and maximize efficiency.”

A typical energy harvesting scheme is composed of an ambient energy source, energy transducer, power management unit, energy storage element, voltage regulator and electrical load.

He then describes in detail (complete with block diagrams) some scenarios: harvesting RF and thermal energy, and solar radiation harvesting.

Overall, the eetimes series on issues regarding embedded design in the IoT era has been a pretty engrossing read. In my next couple of posts, I’ll be summarizing their articles on edge processing and device security. So stay tuned!