CMSIS-RTOS2 Version 2.1.0
Real-Time Operating System: API and RTX Reference Implementation
The CMSIS-RTOS API Version 2 (CMSIS-RTOS2) is a generic RTOS interface for ARM® Cortex®-M processor-based devices. It provides a standardized API for software components that require RTOS functionality and gives therefore serious benefits to the users and the software industry:
The CMSIS-RTOS2 manages the resources of the microcontroller system and implements the concept of parallel threads that run concurrently.
Applications frequently require several concurrent activities. CMSIS-RTOS2 can manage multiple concurrent activities at the time when they are needed. Each activity gets a separate thread which executes a specific task and this simplifies the overall program structure. The CMSIS-RTOS2 system is scalable and additional threads can be added easily at a later time. Threads have a priority allowing faster execution of time-critical parts of a user application.
The CMSIS-RTOS2 offers services needed in many real-time applications, for example, periodical activation of timer functions, memory management, and message exchange between threads with time limits.
The CMSIS-RTOS2 addresses the following new requirements:
As a consequence of these requirements the CMSIS-RTOS2 has the following fundamental modifications:
mainis no longer started as a thread (this was an optional feature in CMSIS-RTOS v1).
CMSIS-RTOS2 provides an translation layer for the CMSIS-RTOS API v1. It is possible to intermix CMSIS-RTOS API Version 2 and CMSIS-RTOS API Version 1 within the same application. Over time, you may migrate to the new API as explained in Migration from API v1 to API v2.
CMSIS-RTOS2 is not POSIX compliant, but has provisions to enable a C++11/C++14 interface.
The following sections provide further details about CMSIS-RTOS2 and the RTX reference implementation.
The following files relevant to CMSIS-RTOS2 are present in the ARM::CMSIS Pack directories:
|CMSIS/RTOS2/Include||cmsis_os2.h header file|
|CMSIS/RTOS2/RTX||CMSIS-RTOS v2 reference implementation based on RTX version 5|
|CMSIS/RTOS2/Template||Compatibility layer to CMSIS-RTOS v1|