Free/Open ARM Cortex MCU Development Tools

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CooCox CoOS  

CooCox CoOS is an embedded real-time multi-task OS specially for ARM Cortex M series.

CoOS Features:

  • Free and open real-time Operating System
  • Specially designed for Cortex-M series
  • Scalable, minimum system kernel is only 974Bytes
  • Adaptive Task Scheduling Algorithm.
  • Supports preemptive priority and round-robin
  • Interrupt latency is next to 0
  • Stack overflow detection option
  • Semaphore, Mutex, Flag, Mailbox and Queue for communication & synchronisation
  • Supports the platforms of ICCARM, ARMCC, GCC

Technical Data:

  • Time Specifications:
N Function Time ( No Robin/Robin )
Create defined task, no task switch 5.3us / 5.8us
Create defined task, switch task 7.5us / 8.6us
Delete task (ExitTask) 4.8us / 5.2us
Task switch (SwitchContext) 1.5us / 1.5 us
Task switch (upon set flag) 7.5us / 8.1us
Task switch (upon sent semaphore) 6.3us / 7.0us
Task switch (upon sent mail) 6.1us / 7.1us
Task switch (upon sent queue) 7.0us / 7.6us
Set Flag (no task switch) 1.3us / 1.3us
Send semaphore (no task switch) 1.6us / 1.6us
Send mail (no task switch) 1.5us / 1.5us
Send queue (no task switch) 1.8us / 1.8us
Maximum interrupt lockout for IRQ ISR's 0 / 0

  • Space Specifications:
Description Space
RAM Space for Kernel 168 Bytes
Code Space for Kernel 974 Bytes
RAM Space for a Task TaskStackSize + 24 Bytes(MIN)
TaskStackSize + 48 Bytes(MAX)
RAM Space for a Mailbox 16 Bytes
RAM Space for a Semaphore 16 Bytes
RAM Space for a Queue 32 Bytes
RAM Space for a Mutex 8   Bytes
RAM Space for a User Timer 24 Bytes
* The data for CoOS kernel is measured for STM32F103RB CPU with the system clock setting to 72 MHz, code execution from internal flash, with Flash Latency 2 wait states and the Prefetch Buffer enabled.

User's Guide:

We have supplied user's guide to help you to use CooCox CoOS more easily and confidently, which includes:

  • Chapter 1 CooCox CoOS Overview
  • Chapter 2 Task Management
  • Chapter 3 Time Management
  • Chapter 4 Memory Management
  • Chapter 5 Intertask Synchronization & Communication
  • Chapter 6 API Reference

To get the details, please download CooCox CoOS User's Guide.


CoOS also provides some examples to help you to develop embedded applications based on CoOS more easily, as follows:

Using ARMCC compiler:
Using ICCARM compiler:
Using GCC compiler:

Supported Devices:

CoOS supports all ARM Cortex M4, M3 and M0 based devices, here only lists some of the most common used:

Download CoOS Source Code:

 Download through CoCenter (Recommend)
 Download directly
* If you have already installed CooCox CoCenter, you could download the software through your local CoCenter.
CoOS V1.1.5 2014-1-13

 CooCox CoOS

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