Introducing Zephyr

The Zephyr OS is based on a small-footprint kernel designed for use on resource-constrained systems: from simple embedded environmental sensors and LED wearables to sophisticated smart watches and IoT wireless gateways.

The Zephyr kernel supports multiple architectures, including ARM Cortex-M, Intel x86, ARC, NIOS II and RISC V. The full list of supported boards can be found here.


The Zephyr project associated with the kernel makes it available to users and developers under the Apache License, version 2.0.

Distinguishing Features

The Zephyr kernel offers a number of features that distinguish it from other small-footprint OSes:

  1. Single address-space. Combines application-specific code with a custom kernel to create a monolithic image that gets loaded and executed on a system’s hardware. Both the application code and kernel code execute in a single shared address space.
  2. Highly configurable. Allows an application to incorporate only the capabilities it needs as it needs them, and to specify their quantity and size.
  3. Compile-time resource definition. Allows system resources to be defined at compile-time, which reduces code size and increases performance.
  4. Minimal error checking. Provides minimal run-time error checking to reduce code size and increase performance. An optional error-checking infrastructure is provided to assist in debugging during application development.
  5. Extensive suite of services. Offers a number of familiar services for development:
    • Multi-threading Services for priority-based, non-preemptive and preemptive threads with optional round robin time-slicing.
    • Interrupt Services for compile-time registration of interrupt handlers.
    • Memory Allocation Services for dynamic allocation and freeing of fixed-size or variable-size memory blocks.
    • Inter-thread Synchronization Services for binary semaphores, counting semaphores, and mutex semaphores.
    • Inter-thread Data Passing Services for basic message queues, enhanced message queues, and byte streams.
    • Power Management Services such as tickless idle and an advanced idling infrastructure.

Fundamental Terms and Concepts

See Glossary of Terms