Battery Powered Azure Sphere MT3620 OS insights
Published Sep 13 2022 09:00 AM 2,504 Views

Batteries are the lifeblood of some of the most exciting tech products coming to market. Laptops and cellphones—of course—but now cars, home automation, security IoT, and industrial IoT sensors or gateways provide new capabilities far away from outlets and power lines. Batteries extend beyond the constraints of grids, the planning of previous builders and installers, and the constraints of time, budget, and convenience.


With our MT3620 22.07 Azure Sphere OS, we’ve improved battery life performance as much as 50 percent in some key scenarios, and we’re targeting additional improvements across a variety of OS components that impact power utilization. Like all Azure Sphere improvements, our customers get this significant upgrade for free, both for new devices being designed, and for devices that have already been fielded. Azure Sphere devices get better over time, enabled by our secure architecture for continuous update, and our commitment to improving the product—and its applications—over the Azure Sphere lifecycle.


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The MediaTek MT3620 Azure Sphere chip is a low-power consumption part that many of our customers have opted to use in battery-powered devices. Since the chip has integrated RAM, Flash and WiFi, it has a small physical footprint and a compressed energy footprint. Battery powered WiFi devices aren’t always the right-fit product, but the MT3620 provides a robust solution when needed.


The Azure Sphere Product Group strongly believes in gathering our own data (the bring Your Own Data, or YODA approach) through customer discovery. Over the past year, we’ve interviewed a number of our customers and listened to their struggles and their successes with building battery-powered devices. Good customer discovery is inductive, not bringing to the table pre-defined constraints or too many hypotheses, but letting problems rise to the surface with empathetic observation and interpreting common themes across multiple customers.


One of the interesting things that we discovered with Azure Sphere was that battery powered devices consumed a lot of time to be ready to communicate with the cloud effectively. While the total OS boot time (<2.5s) was quick for a Linux kernel-based OS product, and certain stages of boot were power-optimized, the system behavior of products based on the MT3620 resulted in significantly more time than necessary between cold boot and useful data transmission to the cloud. While battery optimization can involve decreasing the milliwatts of power consumed by operations, in this case, by listening to our customers, it became clear that we needed to focus on decreasing the number of seconds in the boot timeline before a device was usefully connected to the cloud.


In response to our customers' insights, we’ve rolled out an energy reduction campaign through updates in our past few releases that target cold boot time reduction. By far, the most significant update was in our MT3620 22.07 OS release, which enabled caching of our DAA certificate. Devices that receive a valid certificate from the cloud can reuse that certificate as long as it remains valid, rather than asking our cloud service to reissue a certificate on each cold boot or wakeup from deep sleep. This certificate caching can save between 3 and 27 seconds in the cold boot timeline, which can significantly improve battery life in some scenarios.


While today we’re celebrating this battery powered device improvement, it reflects a broader picture of how IoT has permanently altered device design and operation. With IoT, devices that are already deployed can receive significant improvements over-the-air. For IoT product platforms, the platform investments made by Microsoft can provide new features and improve behavior for all our customers at once, and our customers can discover how Azure Sphere devices get better with time. A product is no longer a snapshot in time of engineering ambition and available technology; with Azure Sphere a product is an ever-growing experience that can continue to drive new value for your business.

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‎Sep 12 2022 11:32 AM
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