potatogim / OmarOS

Omar OS is a Real-Time Operating System written from scratch with ARM CMSIS for easy porting, targeting embedded devices, featuring a full-preemptive scheduler with round robin for same priority tasks, mutexes, task delays, and priority ceiling technique!

OmarOS

⚠️ This project is made for educational and learning purposes and it may contain faults that I didn't discover yet. If you find any, please do a pull request or fork the project to add the modifications.

Omar OS is a Real-Time Operating System written from scratch, targeting embedded devices, and is built on the ARM CMSIS V5 Library for easy porting

Features:

1- Fair scheduling policy: featuring a full-preemptive priority-based scheduler, OmarOS supports a round-robin policy for same-priority tasks.

2- Low resource consumption: OmarOS only consumes 7% of the Cortex-M3 CPU usage in the idle state (no tasks are running), thanks to the "WFE" instruction which allows the CPU to enter sleep mode while not running any tasks

3- Event and Time triggered scheduler: OmarOS allows the user to choose between letting the tasks activate/terminate either by themselves or by an event, or by using delays to run the tasks periodically!

4- Easy task synchronization: OmarOS supports Mutexs, which allows one task to wait for an acquired mutex and to be activated once the mutex is released!

5- No mutex releases by mistake: OmarOS respects the Mutex ownership concept and allows only the task that is holding the mutex to release it.

6- Priority Inversion is no more: OmarOS features the priority ceiling technique which helps in avoiding the priority inversion problem!

Supported APIs:

• OmarOS_Init: Initializes the OS control and buffers
• OmarOS_CreateTask: Creates the task object in the OS and initializes the task's stack area
• OmarOS_ActivateTask: Sends a task to the ready queue to be scheduled
• OmarOS_TerminateTask: Sends a task to the suspended state
• OmarOS_StartOS: Starts the OS scheduler to begin running tasks
• OmarOS_TaskWait: Sends a task to the waiting state for a specific amount of Ticks
• OmarOS_AcquireMutex: Tries to acquire a mutex if available
• OmarOS_ReleaseMutex: Releases a mutex and starts the next task that is in the queue (if found)

Examples:

In this example there are 3 tasks with the same priority, running sequentially with the round-robin scheduling policy

This example shows 3 tasks, each running with a specific delay, task 1 runs every 100ms, task 2 runs every 300ms, and task 3 runs every 500 ms

This example shows the CPU utilization when the OS is not running any tasks, the CPU load is at 7% so it is not consuming excessive energy or resources