What's New in Zephyr 4.2?

Sept. 18, 2025

Check out the highlights in the latest incarnation of the Zephyr OS.

Related To:

Benjamin Cabé does a much better job of highlighting the latest additions to the Zephyr OS, as he takes a deep dive for about three quarters of an hour (watch the video above). Well worth watching if you have the time. If not, here are a few of the highlights, including the signifcant support for MQTT:

Renesas RX architecture now supported
Zephyr SDK 0.17.2 - features include OpenOCD support and its own QEMU emulator
USB Video Class support
Searching for shields in the board catalog is now easier
Twister power harness
MQTT 5.0 support added
Updated Bluetooth Classic support
Zbus graduates to stable API, providing a lightweight software bus for thread communication

More Zephyr OS Content

RTOS: Zephyr Project

Check out this TechXchange that examines the compact Zephyr Project RTOS.

How To Use Zephyr Overlays

Zephyr is a compact RTOS designed for resource constrained systems. This video highlights the use of code overlays.

About the Author

William G. Wong | Senior Content Director - Electronic Design and Microwaves & RF

I am Editor of Electronic Design focusing on embedded, software, and systems. As Senior Content Director, I also manage Microwaves & RF and I work with a great team of editors to provide engineers, programmers, developers and technical managers with interesting and useful articles and videos on a regular basis. Check out our free newsletters to see the latest content.

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I earned a Bachelor of Electrical Engineering at the Georgia Institute of Technology and a Masters in Computer Science from Rutgers University. I still do a bit of programming using everything from C and C++ to Rust and Ada/SPARK. I do a bit of PHP programming for Drupal websites. I have posted a few Drupal modules.

I still get a hand on software and electronic hardware. Some of this can be found on our Kit Close-Up video series. You can also see me on many of our TechXchange Talk videos. I am interested in a range of projects from robotics to artificial intelligence.