We are pleased to announce the release of Zephyr version 4.3.0 🎉🪁
Major enhancements with this release include:
USB Device "Next" stack is now the default
The new USB device stack, built on the modern UDC (USB Device Controller) API, replaces the legacy stack and brings support for multiple simultaneous controllers, runtime configuration, and overall better architecture. The legacy stack is now deprecated and will be removed in Zephyr 4.5.
CPU load and dynamic frequency scaling subsystems
A new experimental CPU frequency scaling subsystem enables dynamic, policy-driven, clock adjustments to balance power consumption and performance Alongside it, a new cpu_load subsystem allows users to obtain CPU usage metrics based on scheduler statistics, which can be used to drive the frequency scaling policy.
Instrumentation Subsystem
A new instrumentation subsystem simplifies tracing and profiling of Zephyr applications by leveraging compiler-managed function instrumentation, allowing the recording of call-graph traces and statistical profiles at runtime.
OCPP 1.6 library
A new OCPP (Open Charge Point Protocol) library enables EV charging station development with Zephyr. The library implements OCPP 1.6 Charge Point functionality over WebSocket, supporting core profile operations including authorization, transaction management, and meter value reporting for communication with Central System servers.
Twister Display Harness
Twister can now validate on-target display output by capturing frames from a USB video camera and matching them against pre-recorded visual "fingerprints".
Developer Experience Improvements
Several new tools have been introduced to help with common development and troubleshooting tasks:
- dtdoctor to help diagnose Devicetree build errors.
- traceconfig build target to help understand where Kconfig symbols come from and their final values.
- Interactive footprint charts to visualize RAM/ROM usage of an application.
Expanded Board Support
Support for 105 new boards and 39 new shields has been added in this release.
Full Release Notes
The full release notes and list of major changes since the last release can be found here.
An overview of the changes required or recommended when migrating your application from Zephyr
v4.2.0 to Zephyr v4.3.0 can be found in the separate migration guide.
Release Lifecycle
The 4.3 release will be supported until October 15th, 2026.
Additional release information may be found on the Release Management Wiki.
Thanks 🙏
Many thanks to the 795 individuals who contributed to this release! 🚀
Johan, Chris, and the Zephyr Release Team