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The Zephyr Project: An RTOS for IoT

The Linux Foundation-backed IoT OS says its governance model and open community ecosystem give it an edge.

How do you develop and sustain an operating system primed for the continuously evolving nature of the internet of things? You model it, in part, on the highly successful Linux platform, which is exactly the tactic of the Zephyr Project, an open, real-time operating system overseen by the nonprofit Linux Foundation along with a variety of other big-name industry players.

The Zephyr Project, which celebrated its one-year anniversary in February 2017, is a modular, scalable platform designed for connected, resource-strained devices. The open source RTOS -- which, in fact, includes no Linux code, but rather is based on the Wind River Rocket IoT OS technology acquired by Intel -- is able to integrate with myriad third-party libraries and embedded devices, regardless of architecture, and was built with security in mind, according to project members. Intel, NXP Semiconductors, Synopsys and UbiquiOS Technology are among the early supporters of the Zephyr Project.

Unlike many of the emerging RTOSes and open IoT OSes that differentiate on the basis of functionality, the Zephyr Project is taking a page out of the Linux playbook, touting its open source governance and licensing model along with its community-based ecosystem as the primary advantages of the platform. While many RTOSes are linked to a specific architecture, the Zephyr IoT OS targets an array of small hardware devices, including Arduinos and ARM SoCs, and is able to serve as a general-purpose OS, unlike many alternative RTOSes, which are limited in functionality or are highly specialized, experts said.

Watch a quick overview of the
Zephyr Project

"The code within Zephyr is not all that new," admitted Geoff Thorpe, head of IoT security at NXP Semiconductors. "But when you look at the IoT OSes out there, both commercial open and closed options, you don't see the community and governance models that have been successful for 20-plus years in bigger, more elaborate computing spaces like servers and networking. The governance model and licensing is what's fundamentally new relative to what's out there."

The Zephyr IoT OS: In the spirit of open source

Optimized for resource-constrained devices, the Zephyr kernel can run on systems as small as 8 KB of memory to as large as 512 KB and can be run as is or tailored to a specific device by enabling or disabling any number of functions. The kernel currently supports a variety of architectures, including the ARM Cortex-Mx, Intel x86, ARC, Synopsys nios2 and RISC-V (coming soon), the developers said. In addition to support for MQTT, SSL and a native, optimized IPv4 and IPv6 dual stack (through incorporation of the Contiki RTOS stack, according to the project's website), Zephyr also includes a full Bluetooth Low Energy  controller and a cryptographic library based on TinyCrypt.

For Linaro, an engineering organization spearheading the development of open source software and tools for the ARM architecture, the Zephyr IoT OS's governance model promises greater stability and staying power in what's still a highly fragmented and nascent IoT OS market, according to Kumar Gala, technical lead for LITE (Linaro IoT Embedded Group). Gala said Linaro, which represents a number of ARM SoC vendors, likes the "meritocracy" structure of the Zephyr Project, which promotes the true spirit of open source by enabling anyone to contribute and modify code as opposed to an ecosystem governed by one or even two principle individuals or companies, Gala said.

"It's about developing code in a true open source manner and we didn't see a lot of [IoT] projects that had that," he said. "Here, you see contributions from all types, from hobbyists to small companies to semiconductor companies. A lot of the projects coming out [in IoT] are from universities and then they try to develop a community around it."

The Zephyr IoT OS is fostering that meritocracy approach through lightweight governance models that marry two broader open source community concepts: encouraging contributions beyond membership companies and ensuring that the project continuously innovates by listening to the needs of the community, explained Sara Sarmiento, product marketing for open source at Intel IoT and the marketing chair for the Zephyr Project. "The governance model of open source is very well-known within the industry and we are enforcing that through our actions," she said.

From a technical standpoint, the open community approach also has merit because it enables developers to leverage the work of others, not repeatedly work from scratch -- a scenario that's all too common in the world of microcontrollers, NPX's Thorpe said. Instead of focusing engineering efforts around the RTOS, Zephyr's approach frees up developers to innovate in other areas, which can aid in competitive differentiation, he said.

"Zephyr's objective is to more or less commoditize the basic requirements of IoT so it's an anti-differentiator from that sense," Thorpe said. "But that means developers can differentiate further up the stack without reinventing the really hard technical wheel."

Next Steps

Check out the Contiki IoT OS, as well as IoT OSes from Google and Electric Imp.

Dig Deeper on IoT APIs, Applications and Software