.. include:: <mmlalias.txt>


Why Use An Embedded RTOS? (2026-09-23 - 2026-09-24)
===================================================

.. topic:: Course Info

   * **Course Material**:
     :doc:`/trainings/material/soup/linux/why/index`
   * **Original Agenda**: :doc:`agenda`

.. toctree::
   :hidden:

   agenda

Intro
-----

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/overview/index`

* Coin terminology: "Interrupt", "ISR", "IRQ", "Spinlock", "Thread",
  "Scheduling", ...
* Quick look into `Zephyr <https://www.zephyrproject.org/>`__, and its
  in-course substitute, :doc:`WhyOS
  </trainings/material/soup/linux/why/overview/index>`

Interrupt Handling
------------------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/interrupt/index`

* Bare metal embedded software: a main loop, and a number of
  interrupts that bring life to the system
* Talk about limitations

Scheduling
----------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/threads/index`

* What is *The Scheduler*?
* The advantages of *waiting*
* Discuss task priorities, timeslices, and preemption

Message Queues
--------------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/messagequeue/index`

* Message queue: easy communication from an ISR to a thread
* ... and between threads
* Main communication device for the rest of the course
* Not the only one: :doc:`pipe
  </trainings/material/soup/linux/why/why-os/pipe>`, :doc:`semaphore
  </trainings/material/soup/linux/why/why-os/semaphore>`, event
  (manual- and auto-reset), ...

Semaphores
----------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/semaphore/index`

* Show how we can implement custom *waiting* scenarios

Didactic Toy Application
------------------------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/datalogger/index`

* Longer live-hacking session with discussion
* Demonstrate how easy life can be when you are allowed to wait
* Create a semi-complex application with :doc:`file
  </trainings/material/soup/linux/why/why-os/file>` and :doc:`network
  </trainings/material/soup/linux/why/why-os/mqtt>` I/O

Events/Polling
--------------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/polling/index`

* Introduce *waiting for multiple events*, and why this is a good
  thing
* Quick example: collapsing two threads into one

Didactic Toy Application, Revisited
-----------------------------------

.. topic:: See also

   * :doc:`/trainings/material/soup/linux/why/datalogger-polling/index`

* Restructure the toy application around a single-threaded event loop

Miscellaneous
-------------

* Room for realtime discussions. Deadlock scenarios; what does it mean
  that Zephyr mutexes do priority inheritance?
* The course uses modern C++ for brevity and clarity. If there is need
  to, we can diverge and explain as needed.