This manual describes the CMSIS-RTOS implementation based on the Keil RTX Real-Time Operating System which is designed for Cortex-M processor-based devices. The RTX kernel can be used for creating applications that perform multiple tasks simultaneously. These tasks are executed by threads that operate in a quasi-parallel fashion.

While it is certainly possible to create real-time applications without an RTOS (by executing one or more tasks in a loop), there are numerous scheduling, maintenance, and timing issues that can be solved better with an RTOS. For example, an RTOS enables flexible scheduling of system resources like CPU and memory, and offers methods to communicate between threads.

CMSIS-RTOS RTX programs are written using standard C/C++ constructs and are compiled with the ARMCC, GCC, or IAR Compiler. The cmsis_os.h header file defines the RTX functions and macros that allow declaring tasks and accessing all RTOS features easily.

This manual contains the following sections:

Overview: Provides an overview about the CMSIS-RTOS RTX and technical specifications.
Revision History : Documents changes made in each version.
Create a CMSIS-RTOS RTX Project : Provides instructions for writing and debugging applications with CMSIS-RTOS RTX.
Configuration of CMSIS-RTOS RTX : Describes configuration parameters of CMSIS-RTOS RTX.
CMSIS-RTOS RTX Tutorial : Is an in-depth tutorial that can be used with any hardware to get a better understanding of the concepts and use cases of a real-time operating system.
Building the CMSIS-RTOS RTX Library : Describes how to build your own CMSIS-RTOS RTX library.
Function Overview : Describes the CMSIS-RTOS API functions that are implemented by RTX.