FreeRTOS
FreeRTOS (pronounced "free-arr-toss") is an open source real-time operating system (RTOS) for embedded systems. FreeRTOS supports many different architectures and compiler toolchains, and is designed to be "small, simple, and easy to use".
FreeRTOS is under active development, and has been since Richard Barry started work on it in 2002. As for me, I'm not a developer of or contributor to FreeRTOS, I'm merely a user and a fan. As a result, this chapter will favor the "what" and "how" of FreeRTOS's architecture, with less of the "why" than other chapters in this book.
Like all operating systems, FreeRTOS's main job is to run tasks. Most of FreeRTOS's code involves prioritizing, scheduling, and running user-defined tasks. Unlike all operating systems, FreeRTOS is a real-time operating system which runs on embedded systems.
By the end of this chapter I hope that you'll understand the basic architecture of FreeRTOS. Most of FreeRTOS is dedicated to running tasks, so you'll get a good look at exactly how FreeRTOS does that.
If this is your first look under the hood of an operating system, I also hope that you'll learn the basics about how any OS works. FreeRTOS is relatively simple, especially when compared to Windows, Linux, or OS X, but all operating systems share the same basic concepts and goals, so looking at any OS can be instructive and interesting.