Thread: Portable cooperative scheduling

I want to design a cooperative scheduling for 32 -bit microcontroller. I have read many links and watched many youtube videos but have no idea how to start design

This is a specification I have create for learning

task 1 takes 2ms to execute
task 2 takes 3ms to execute
task 3 takes 2ms to execute

task 1 should be run within 5ms deadline
task 2 should be run within 10ms deadline
task 3 should be run within 15ms deadline

Code:

int main ()
{
  
   while (1)  
   {
   
  }
return 0;
}

void ISR ( ) // timer interrupt set every 1ms 
{

}

any thoughts idea

Originally Posted by Salem

Did you learn anything from your previous round of threads?
How do you design scheduler ?
Top design- real time operating system
How to write code for round robin scheduling
Free rtos code example 1

> I have read many links and watched many youtube videos but have no idea how to start design
So what is your current design and programming experience?

I have successfully ported freertos on 32 bit micro. I done few experiments for learning.

Originally Posted by stahta01

How long does it take to switch between tasks?
Are you going to use/support a yield() command?
That is the normal commanded by several multitask API when a process is done using current time slice.
Are you going to use interrupts to trigger task switching?

Edit: Add more info below
Note: I have never designed this type of system in C; I think I may have did in Ada once.
But, if it takes a long time to switch tasks I would likely use a larger default time slice/interval.
I am guessing from what you posted that the choices are 1ms, 2ms, and 3ms.
If the requirement is to use 1ms; then the answer to how long to switch really does not matter except if it is too large there will be no possible working solution. In other words, if the time to switch tasks is 1.1 ms; then, there is likely no possible solution using task switch using an 1ms time task interval.

Tim S.

When there are multiple task's, scheduler need to decide when and which one task should be run on machine

Task should be switched at 1ms time interval

Originally Posted by Salem

>I have successfully ported freertos on 32 bit micro.
I'm confused as to what it is you actually want, if you already have an RTOS running on your platform.

I want to write my own code for scheduling without freeRTOS just for learning. I am having trouble to making it.

This is what I want to implement with 1ms system tick

Originally Posted by Salem

Your picture is pre-emptive, not co-operative.

yes, It's pre-emptive design

Originally Posted by Salem

Which micro-controller are you trying to use?

currently working with PIC18F45K80, MPLAB Xc8, C language, Planning to move on 32 PIC very soon