RTOS implementation.

[future]

Hello everybody,

I am implementing a simple rtos with just 4 primitives: Timing, messages, events and counting semaphores.

Tasks run when the kernel dispatches one of these primitives.

Timing handles the task delays and timeouts.
Messages passes a pointer from task to task by the use of a third object (messagebox)
Events send a signal to all registered tasks on this object (eventbox)
Semaphore is an object that provides means to track resource usage.

All of these kernel calls suspends the sending task until the messages/events are sent and processed by the receivers... then sender task is resumed.

If there is nothing to do, idle callback runs.

Now the question. This simple kernel can be used to help solve many programming problems, but how complex do you think it can be? My opinion is that it can grow to a really bigger system if I/someone can port comms and other stacks to it.

 

[Raj Gunaseelan]

Hi future,
Really a good idea. But, do you have any reason to start creating a kernel from scratch rather than using open source kernels out there?


Regards,
Raj Gunaseelan

 

[future]

I am doing it as proof of concept on my free time... not actually building other projects on top of it.

 

[Raj Gunaseelan]

how complex do you think it can be?

What microcontroller/processor are you planning to use? If the architecture and the available memory(both ROM and RAM), it can be sophisticated to a level. It is better to start reading the code of existing RTOSes to have a better idea of implementation. I use freeRTOS. I am unfamiliar with others. Another thing, even if a good RTOS is got up, developing the debug tools can be a pain(I guess so!).

Regards,
Raj Gunaseelan

 

[btbass]

I have written and posted a lightweight rtos for Microchip pic24, pic30 and pic33 and posted it here.

http://embeddedcodesource.com/developer/rj_components/rtos_for_pic24_pic30_and_pic33

Might give you some ideas on how to implement yours.
Good luck with your program.