ChibiOS

ChibiOS is a complete, free embedded development environment: a family of small, fast and formally structured RTOS kernels, device driver frameworks, a sandboxing subsystem and a set of support libraries, all designed to work together on microcontrollers ranging from small single-core devices up to multi-core ARM and RISC-V systems.

• Website: https://www.chibios.org
• Documentation: https://www.chibios.org/dokuwiki/doku.php?id=chibios:documentation:start
• Forum: https://forum.chibios.org
• Change log: CHANGELOG.md

Components

Component	Description
RT	Full-featured hard real-time kernel: preemptive scheduling, tickless mode, SMP support, virtual timers, synchronization primitives, registry, functional safety module.
NIL	Minimal RTOS kernel for resource-constrained devices, offering a compatible subset of the RT API in a fraction of the footprint.
SB	Sandboxes: isolated execution environments with MPU protection, optional full virtualization with virtual IRQs, ELF loading, per-sandbox VFS and Posix-flavored API, and para-virtualized driver access (VIO).
HAL	Hardware abstraction layer: a portable device driver model plus peripheral drivers for the supported microcontroller families.
XHAL	New-generation HAL with an object-oriented driver model, partially generated from XML descriptions (os/xhal/codegen).
EX	Drivers for external peripherals such as sensors, connected through HAL interfaces.
OSLIB	Kernel-agnostic services library: heaps, memory pools, mailboxes, objects factory, memory areas and checker functions.
VFS	Virtual file system layer with FatFS and littlefs bindings and overlay support.
VNS	Network stack infrastructure (in development).
TEST	Portable test engine (os/test): a framework for building structured, repeatable test suites, generated from XML descriptions; used by the ChibiOS test suites but usable as a product in its own right.

External libraries integrated under ext/: FatFS, littlefs, lwIP, wolfSSL.

Supported hardware

• HAL ports: STM32 (most families), Raspberry Pi RP2040 and RP2350 (both Cortex-M33 and Hazard3 RISC-V cores), SPC5, LPC, AVR, ADUCM, MAX32, plus Posix and Win32 simulators for development and testing.
• XHAL ports: STM32 (selected families), Raspberry Pi RP2040 and RP2350 (ARM cores).
• Kernel ports: ARM Cortex-M (ARMv6-M, ARMv7-M, ARMv8-M, including alternate ports optimized for sandboxing and fast context switch), classic ARM7/9, Cortex-R, Hazard3 RISC-V, Power e200z, AVR.

Getting started

Demo projects live under demos/, one directory per platform. Each demo is self-contained, with its own configuration files and makefile. With GNU Make and an arm-none-eabi GCC toolchain installed:

cd demos/STM32/RT-STM32F407-DISCOVERY
make

The Posix simulator demos (demos/various) build and run natively on Linux, so the kernels can be tried without hardware.

An optional VS Code dev container with all required tools is provided in .devcontainer/ (see its README for details).

Repository layout

├── demos/         Demo projects, one directory per platform.
├── doc/           Documentation builders (Doxygen).
├── ext/           External libraries, not part of ChibiOS.
├── os/
│   ├── common/    Shared modules: startup, CPU ports, OOP framework,
│   │              CMSIS-OS and NASA OSAL abstraction layers.
│   ├── rt/        RT kernel.
│   ├── nil/       NIL kernel.
│   ├── oslib/     OSLIB, usable by both RT and NIL.
│   ├── sb/        Sandboxes subsystem.
│   ├── hal/       HAL framework, drivers, OSAL and platform ports.
│   ├── xhal/      New-generation HAL and its code generator.
│   ├── ex/        External peripherals (sensors) drivers.
│   ├── vfs/       Virtual file system.
│   ├── vns/       Network stack infrastructure.
│   ├── test/      Portable test engine.
│   └── license/   Licensing headers and deployment options.
├── test/          Test suites for the various components.
├── testhal/       HAL integration test demos.
├── testex/        EX integration test demos.
├── testrt/        RT validation projects.
├── testsb/        Sandboxes validation projects.
├── testxhal/      XHAL validation projects.
└── tools/         Build tools, code generators, style checkers, updaters.

Testing

Testing is built on the portable test engine under os/test. The test/ directory contains the test suites for the various components (RT, NIL, OSLIB, HAL, VFS and more), functional and benchmark, used by the demos; testhal/, testex/, testrt/, testsb/ and testxhal/ contain build and integration test projects for the various subsystems, including MISRA checks and code coverage projects.

Contributing

Development happens on the master branch, with stable-* maintenance branches and ver_* release tags. See AGENTS.md for project structure, coding style and contribution guidelines.

License

ChibiOS uses different licenses for different components:

• The RT and NIL kernels and related kernel components are released under GPLv3 (see license.txt). Alternative licensing options, including a GPL linking exception and commercial licenses, are available; see os/license/ and https://www.chibios.org for details.
• The HAL and other middleware components are released under the Apache License 2.0.

Refer to the header of each source file for its exact license.