The µOS++ IIIe Project

Last modified on Mon Nov 14 08:50:12 2022 UTC.   Improve this page

The µOS++ IIIe (micro oh ɛs plus plus third edition) project is the third iteration of µOS++, a POSIX-like, portable, open source, royalty-free, multi-tasking real-time framework intended for 32/64-bits embedded applications, written in C++. The project is hosted on GitHub as micro-os-plus. It has a comprehensive User’s manual. The APIs are documented in the µOS++ reference.

POSIX++ is another point of view of the project; with most system APIs using the POSIX semantics, but being written in C++, the µOS++ IIIe APIs can also be seen as a C++ version of POSIX, thus the name POSIX++.

Manyfold identity

The µOS++ IIIe project can be considered from several points of view.

The µOS++ framework/APIs

Although generally associated with its RTOS, µOS++ IIIe is actually a framework, a collection of APIs, components and technologies.

One of the main APIs is the µOS++ RTOS API, but applications based on µOS++ may run very well without a RTOS, or even use a different RTOS.

For a better portability, the entire framework is layered, the µOS++ RTOS API provides a common public interface to the applications, but the implementation is separate, it might be that of its own µOS++ RTOS reference implementation, but it may very well be another implementation, even a custom one specific to the application.

The µOS++ RTOS implementation

From an embedded system point of view, µOS++ IIIe provides the reference implementation for the scheduler and portable synchronisation objects (like mutex, semaphore, etc).


The µOS++ packages

From a modular point of view, µOS++ IIIe is a collection of packages hosted on GitHub in two locations:

  • the original code is grouped under the µOS++ IIIe GitHub collection of projects
  • projects based on third party code are grouped under the xPacks collection.
µOS++ Collection


Unless otherwise mentioned, all µOS++ IIIe components are provided free of charge under the terms of the MIT License, with all rights reserved to Liviu Ionescu.