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Zephyr Project at FOSDEM 2025: A Recap Blog

By February 11, 2025February 17th, 2025No Comments

The Zephyr Project had an exciting presence at FOSDEM 2025. This year was special because, in addition to our community’s talks, we also had our own stand at Building K, Level 1. Here is a quick recap of what made this year’s event so great for us.

A major highlight of FOSDEM 2025 was the selection of several exciting talks that highlighted the flexibility and innovation of Zephyr RTOS:

SatNOGS-COMMS: An Open-Source Communication Subsystem for CubeSats

SatNOGS-COMMS is an open-source, open-hardware communications subsystem for CubeSats, developed by the Libre Space Foundation in collaboration with the European Space Agency (ESA). This innovative system combines advanced hardware and software to meet the challenges of CubeSat missions while promoting accessibility and flexibility through an open ecosystem.

The subsystem features an STM32H743 microcontroller as its main processor, complemented by a ZYNQ-7020 FPGA accelerator for computationally intensive tasks. SATNOGS-COMMS is built on Zephyr RTOS, with the firmware written entirely in C++17. Notably, its hardware control interfaces follow a platform-agnostic architecture, enabling users to adapt the firmware to their preferred RTOS with minimal effort.

This presentation will delve into the software engineering decisions, challenges encountered, and the advantages of an open-source approach for CubeSat missions and space exploration.

ZSWatch – The Open Source Smartwatch

Together with Jakob Krantz, Daniel Kampert is working on an Open Source Smartwatch, called ZSWatch.

https://github.com/jakkra/ZSWatch. The talk introduced the project to the community to find additional contributors. Daniel gave a rough overview about the past and current development, new ideas and probably open questions.

(Note: Video recording will be shared here as soon as the FOSDEM page publishes the talk)

Zephyr: Open Source Project Best Practices Over Time

In 2024, the Zephyr project hit a milestone by becoming one of the few open source projects with over 100,000 commits in it’s main repo. Why are developers joining and contributing to it?

When the project launched in 2016, there was the commitment from the start apply known best practices to its development. While Zephyr is a different code base, a lot of the lessons learned from the Linux Kernel Community were applied to forming it’s community. The project focused on incorporating security best practices as the were identified right from the start, and is now working towards formal safety certification.

This talk will go through some of the best practices that have been applied for developing open source projects, and illustrate the results of applying these best practices.

Zephyr RTOS Roasting Party

You’ve heard it from colleagues, you’ve seen it on Reddit… Zephyr RTOS can be difficult to navigate.

Join this session for a “Zephyr Roasting Party” where we’ll openly look at and discuss the most complained-about aspects of Zephyr, and try to honestly answer common questions and criticisms such as:

  • “Zephyr is bloated and really has poor real-time performance compared to other RTOSes”
  • “I already have a HAL from my silicon vendor, why would I need even more HW abstractions?”
  • “Devicetree is so complex! How do I even understand what’s going on with all these ‘macrobatics’?”
  • “There’s lots of drivers available upstream, sure, but how do I know how mature they are?”
  • “What is this west thing, and why are you asking me to learn Python?”
  • “Why is my board/driver not supported?”

The goal of the talk is NOT to rhetorically question some of the “bad” parts of Zephyr, only to immediately tell you why Zephyr is in fact the best thing since sliced bread. Instead, we will honestly discuss these pain points to help you understand better some of the design decisions behind Zephyr, and why they might (or might not!) actually be worth the steep learning curve.

Open-Source CPU: Deep-dive into RISC-V CFU and Zephyr

RISC-V’s instruction set architecture (ISA) has enabled seasoned embedded software engineers to experiment with FPGAs since numerous open-source RISC-V cores can be flashed onto an FPGA.

The Zephyr Project is rapidly emerging as a leading real-time operating system (RTOS). Zephyr integrates open-source and security best practices to ensure a vendor-neutral, secure, and reliable platform.

One of the exciting features of the RISCV ISA is the Custom Function Unit (CFU), which enables a framework to support custom operations in hardware, which is accessible from software. In this talk, Mohammed will provide an in-depth demonstration on how to add a CFU into a RISCV core on an FPGA, how to make the appropriate calls from Zephyr, and the possibilities that the CFU enables for hardware acceleration in embedded systems.

Developing BLE Host Applications with Zephyr

Bluetooth Low Energy, commonly abbreviated as BLE, is a well-known wireless communication technology aimed at low-power applications. It divides devices into two categories: low-cost, potentially high volume, battery constrained peripheral devices such as head phones or heart rate monitors, and comparatively more powerful and less constrained central devices, such as smartphones and notebooks.

The Zephyr Project has supported developing BLE peripheral applications for a long time. But it may not be well known that it also supports BLE host applications, or central devices as the standard calls them. In his talk, Florian will take a look at how we can develop BLE host applications using Zephyr. After a (very) short introduction to the BLE protocol stack, he will delve into Zephyr’s Bluetooth API and more importantly talk about the pitfalls he encountered while getting his feet wet with Zephyr. On the practical side, this talk will look into how BLE applications remain portabile between boards by different vendors, and how the many BLE-enabled emulators and simulators provided by Zephyr can be used for quicker development and testing.

In this talk you will learn about:

  • the basics of the BLE protocols
  • the Zephyr Bluetooth API and its pitfalls
  • how portable Zephyr applications using BLE are
  • how you can utilize the Zephyr emulators and simulators for BLE development

The USB-MIDI 2.0 device class in Zephyr

A few years ago, a musician friend of mine reached out, hoping to build a custom controller for a live act performance. Together, we decided on a USB-MIDI device, which soon became a hands-on learning journey into Zephyr, USB development, and the MIDI protocol.

MIDI (Musical Instrument Digital Interface) has been the leading standard for connecting digital instruments and controllers since the 1980s. Although USB includes MIDIStreaming (a subclass of the Audio device class), Zephyr had no support for it. So, I decided to build one.

In this talk, I’ll walk you through my adventures implementing (and eventually upstreaming) this new device class. We’ll start by revisiting the original MIDI 1 protocol from the eighties, the original USB-MIDI1.0 from the 2000s and the updated USB-MIDI2.0 specification from 2020. After a brief refresher on USB devices, I’ll introduce the USB MIDIStreaming interface and the various supported topologies. Finally, we’ll see how to bring it all together using Zephyr USB device_next, and how it is used from your application’s code. In the end, we should be able to make any kind of MIDI speaking device using our favorite kite-stamped RTOS.

Alongside this technical content, I may relate my experience as an occasional hobbyist contributor since Zephyr 1.14, and how I navigated spec updates (Device tree changes, USB-MIDI 1.0 to 2.0, Zephyr USB device next).

Embedded Video Systems With Zephyr

Zephyr is a real-time operating system providing Video APIs to embedded devices. It enables building video feeds out of any supported hardware, low-power or high-performance alike.

The image sensor market explodes and cameras are used for many purposes: optics, electronics and signal processing is empowering medical imaging, agriculture, drones, conferencing, traffic monitoring, robotics, automation, scientific equipment… Through computer vision, imaging becomes an integral part of an information system around it: images that act.

A Zephyr-themed overview of the video information chain, from photons to software APIs.

(Note: Video recording will be shared here as soon as the FOSDEM page publishes the talk)

Community Engagement

At our stand in Building K, Level 1, attendees had the chance to interact with the Zephyr project community through live demos, product displays, and discussions with our maintainers and community members.

Zephyr RTOS is powering a variety of innovative products across different industries. Some of the key products showcased include:

One of the product demos included two custom webcam devices using the new USB Video Class (UVC) protocol in Zephyr: RPi Pico at 640×480 at 10 FPS, tinyCLUNX33 at 1920×1080 at 30 FPS prepared by Josuah Demangeon, Panoramix Labs.

 Attendees also got to pick up some fun Zephyr swag, like kites, stickers, and magnets, making their FOSDEM experience even more memorable.

Looking Ahead

Looking back at FOSDEM 2025, we are proud of our community’s contributions and the positive feedback we received. Whether you came for the talks, networking, or to experience the open source community, we appreciate your support. 

In addition to FOSDEM, we have the upcoming meetups and conferences where you can connect with the Zephyr community. One key event to look out for is the Embedded World Conference and Exhibition. Be sure to check out our event page for details and stay tuned for more exciting announcements. Join our community in Discord to ask questions, share insights and get the latest information.