µOS++ is a POSIX-like open-source framework for writing embedded applications, written in C++. It includes multiple components, like startup, memory allocators, a multi-threaded scheduler, device drivers, files, file systems and more.
The open-source project is hosted on GitHub as micro-os-plus/micro-os-plus-iii.
This page is addressed to developers who plan to include this source code library into their own projects.
For maintainer info, please see the README-MAINTAINER file.
The µOS++ (micro oh ɛs plus plus) project is the third iteration of µOS++, a POSIX-like, portable, open-source, royalty-free, multi-tasking real-time framework written in C++, intended for 32/64-bits embedded applications.
The APIs are documented in the µOS++ reference.
As a source code library, this project can be integrated into another project in the traditional way, by either copying the relevant files into the target project, or by linking the entire project as a Git submodule.
However, the workflow can be further automated and the most convenient way is to add it as a dependency to the project via xpm.
Along with the source files, this project also includes a
package.json file with the metadata that allows it to be identified as an
xpm/npm package that can be installed automatically as a dependency.
A recent xpm, which is a portable Node.js command line application that complements npm with several extra features specific to C/C++ projects.
It is recommended to install/update to the latest version with:
npm install --global xpm@latestFor details please follow the instructions in the xPack install page.
Warning: Be sure xpm is not installed with administrative/root rights.
This source code library can be installed as a sub-folder below xpacks with:
cd my-project
xpm init # Add a package.json if not already present
xpm install github:micro-os-plus/micro-os-plus-iii#v7.0.0 --save-dev --copy
ls -l xpacks/@micro-os-plus/micro-os-plus-iiiNote: On Windows use dir and back-slashes.
Note: Without --copy, the default is to create a link
to a read-only instance of the package in the xpm central store.
The package can also be installed with npm
or related, but the content will end in the node_modules folder,
along with JavaScript code;
therefore it is recommended to install C/C++ packages via xpm.
If, for any reason, xpm/npm are not available, it is always possible to manually copy the relevant files into the target project. However, this will need extra maintenance to keep the project up to date.
A more convenient
solution is to link the entire project as a Git submodule,
for example below an xpacks folder:
cd my-project
git init # Unless already a Git project
mkdir -p xpacks
git submodule add https://github.com/micro-os-plus/micro-os-plus-iii.git \
xpacks/@micro-os-plus/micro-os-plus-iiiThe current µOS++ code tries to be as portable as possible.
The following related projects complement µOS++ with specific implementations for different platforms:
- the Cortex-M port of the scheduler is in the separate project µOS++ Cortex-M
- the synthetic POSIX port of the scheduler is in the separate project µOS++ POSIX arch
Third party source code libraries are available from
- https://github.com/xpacks - deprecated since mid 2023
- https://github.com/xpack-3rd-party
Apart from the unused master branch, there are two active branches:
xpack, with the latest stable version (default)xpack-develop, with the current development version
All development is done in the xpack-develop branch, and contributions via
Pull Requests should be directed to this branch.
When new releases are published, the xpack-develop branch is merged
into xpack.
The µOS++ IIIe source code is split between a portable part (this project) and platform specific code (like Cortex-M). Applications must include both.
The code is relatively complex, and includes multiple components in a monolithic repository. Most components use conditional compilation and require preprocessor definitions to enable them, otherwise they are not included in the build.
µOS++ IIIe is fully functional for Cortex-M devices and also runs on synthetic POSIX platforms (like macOS and GNU/Linux).
Note: The next edition of the project (IVe) is currently work in progress, with the monolithic repository to be split into multiple separate source code libraries.
The project is written in C/C++ and it is expected to be used in C and C++ projects.
The source code was compiled with GCC 11/12, clang 12/13/14/15, arm-none-eabi-gcc 12, and should be warning free.
To ease the integration of this package into user projects, there are already made CMake configuration files (see below).
For other build systems, consider the following details:
The following folders should be passed to the compiler during the build:
include
The source files to be added to the build are in the following folder:
src
There are multiple definitions, grouped by various criteria. For details, see µOS++ Application Config.
-std=c++20or higher for C++ sources-std=c11for C sources
The portable part of µOS++ is monolithic and does not have direct dependencies; however applications must include the platform specific implementation, like for Cortex-M.
To integrate the micro-os-plus-iii source code library into a CMake application, add this folder to the build:
add_subdirectory("xpacks/@micro-os-plus/micro-os-plus-iii")The result is an interface library that can be added as an application dependency with:
target_link_libraries(your-target PRIVATE
micro-os-plus::iii
)- none
- none
- none
tests/rtos-apis- simple test to exercise the µOS++ RTOS C++ API, the C API and the ISO C++ APItests/mutex-stress- a stress test with 10 threads fighting for a mutextests/cmsis-os-validator- the Arm CMSIS OS validator
The Arm CMSIS RTOS validator is available from the separate project xpacks/arm-cmsis-rtos-validator.
For guidance on how to structure projects using µOS++,
including integration with CubeMX for STM devices,
please see the tests folder and the Eclipse projects in the separate
GitHub eclipse-demo-projects.
According to semver rules:
Major version X (X.y.z | X > 0) MUST be incremented if any backwards incompatible changes are introduced to the public API.
The incompatible changes, in reverse chronological order, are:
- v7.x: two minor changes spotted by GCC 12
- a name clash between the
file_system()method and the class; the method was renamed toget_file_system() - a name clash between the unscoped enum
socketdefinition and the top definition; the definition was changed to a scopedenum class
- a name clash between the
Unless otherwise stated, the content is released under the terms of the MIT License, with all rights reserved to Liviu Ionescu.