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Why developers should choose Zephyr RTOS

Software Development

7 mins read

Zephyr RTOS is a scalable real-time operating system (RTOS) designed to support multiple hardware architectures, specifically devices with limited resources while providing high security  features. Typical applications include simple embedded devices such as environmental sensors through to more complex devices, such as smartwatches and IoT wireless applications.

That’s a lot of words, but what do they all mean? How is Zephyr different from other operating systems, and what makes Zephyr special? We will try to answer these questions and more.



What is an RTOS, and why is it different from a standard operating system (OS)?


We are all familiar with standard operating systems such as Android, iOS, Windows, and Linux. Such systems manage the hardware resources of computing applications that run on devices such as computers and smartphones. They provide the software link between the device hardware and its user while allocating resources such as access to the device’s central processing unit (CPU), storage, and memory to applications currently running. The OS carries this out by sequentially running an array of processes.


An RTOS takes a radically different approach. Rather than undertaking a sequential array of tasks, it operates in near-real-time, responding rapidly to stimuli that may arise from sources external to the device. Furthermore, while it carries out similar functions to an OS, an RTOS prioritises timing over results. In other words, an OS such as Windows manages user responsiveness to multiple programs and services, allocating resources “fairly” between them; an RTOS focuses on critical applications that require precise timing.


Some examples of where you would use an RTOS include:

  • Emergency air-bag deployment in a car – precise timing is crucial to avoid injury
  • Automatic parts inspection on a production line – any delay would reduce productivity
  • Air traffic control where rapid repose to external stimuli is life-critical


To sum up the differences between an OS and an RTOS: an OS provides no guarantees on timing – it does its best to keep all scheduled tasks running. On the other hand, an RTOS will focus all its resources on a critical task and guarantee to complete it within a specified timeframe.



What makes Zephyr RTOS special?


Now that we understand what an RTOS is and when one is needed, we will look at what is special about the Zephyr RTOS.


The Zephyr Project is managed by the Linux Foundation, a non-profit organisation whose mission is to create sustainable ecosystems around open-source projects, thus accelerating technology development and commercial application.


The fact that it is independent and not tied to a controlling commercial organisation while also being developed and adopted in the open-source GitHub repository means that it attracts many contributions from many different contributors.


There are, of course, many alternative real-time operating systems that perform similar tasks as  Zephyr. Some of the most well-supported  of these include FreeRTOS, backed by Amazon and Azure RTOS (ThreadX), supported by Microsoft. However, none of these receives anything like the number of contributions made to Zephyr. The image below shows a composite of the historical contributions made to all of these (data sources from GitHub). Again, it is clear that Zephyr receives much  more real contributions – by over several orders of magnitude.



Other factors that put Zephyr RTOS ahead of the alternatives include its strong focus  on security and safety certification.



Security is vital to all distributed systems, which must be protected from potential hackers. The Zephyr project maintains a security overview that sets out security compliance requirements for developers and the security process steps to be followed. These are shown below.


Safety may be seen as the other face of security. While security protects the system from hackers, safety measures safeguard people and the surrounding world from the system. The Zephyr project aims to become safety certified over the next two years, specifically on achieving international functional safety standard-61508 certification, which applies to a wide range of industries.



The Zephyr Community


As we have seen, Zephyr’s rapid growth is powered by its extensive community. This includes names such as Intel, Nordic Semiconductor, Oticon, NXP, Google, Facebook, and T-Mobile, all of which are platinum members. Google and Facebook joined Zephyr in 2020 and T-Mobile in 2022. Here are some of the reasons why these industrial behemoths signed up:


“Google believes in building secure products for all of our users, and we are excited to join forces with Zephyr to develop a secure real-time operating system. The Zephyr Project has built a strong community of experts, and we look forward to working with all participating organizations to improve the state of the RTOS our products depend on.”

Puneet Kumar, Director of Engineering, Chrome OS


“Facebook is pleased to support the Zephyr project, which shows great promise in accelerating the pace of RTOS innovation. The project’s focus on establishing neutral governance, encouraging a diverse development community, and the attention to security will help create a thriving and sustainable open-source ecosystem around Zephyr. We are excited to be part of that.”

Ric Wheeler Engineering Manager & Olof Johansson, Engineering Director, Facebook


“T-Mobile is thrilled to be the first wireless provider to join the Zephyr Project. As we shared when we launched DevEdge earlier this month, we envision a future where everything that can be connected will be. And that requires massive innovation. Zephyr’s RTOS will help T-Mobile enable developers to build better and faster, unlocking massive innovation on our network.”

Rob Roy, SVP of Emerging Business Innovation at T-Mobile


Underpinning the rapid growth and output of the Zephyr community is the fact that collaboration is no longer optional  in the rapidly developing world of connected devices. The challenges outpace any individual company, and collaboration is the only way to reduce costs and achieve an acceptable time to market. As a result, Zephyr RTOS is truly open source, can be applied to a wide range of diverse applications, and supports more hardware devices than any other RTOS.



Getting started with Zephyr


While there are several levels of Zephyr membership: Platinum, Solver, Associate, and Community, with membership fees for a platinum member starting at $100,000, you do not need to be a member to participate – individual developers are welcome to contribute. A getting started guide is available for Ubuntu, macOS, and Windows, along with various samples and demos. Setting up your development  environment is relatively painless, and help is usually available  on Zephyr’s Discord server. If you are in search of an RTOS, there is nowhere better to start your journey.



Zephyr and the future


The IoT is a growing space. It achieved 22% growth in 2021 and could reach a market of $525 billion by 2027. There is no doubt that RTOS will be crucial for much of this growth. The ecosystem will inevitably see considerable consolidation as smaller players fall by the wayside or are absorbed by larger fish. Cost, performance, scalability, and security will be major issues.


While nothing is certain, with many of the world’s biggest players supporting it, we can see no good reasons why today’s developers should choose an RTOS other than the Zephyr RTOS. It certainly appears to be the one to back.