“A real-time operating system (RTOS) is an operating system (OS) for real-time computing applications that processes data and events that have critically defined time constraints. […] All operations must verifiably complete within given time and resource constraints or else fail safe. Real-time operating systems are event-driven and preemptive, meaning the OS can monitor the relevant priority of competing tasks, and make changes to the task priority.” (Wikipedia)

• Real-Time OS: https://en.wikipedia.org/wiki/Real-time_operating_system
• Real-Time Computing: https://en.wikipedia.org/wiki/Real-time_computing

An excellent practically oriented introduction to RTOS and FreeRTOS by Shawn Hymel on DigiKey@YouTube

This course covers general theoretical concepts of Real-Time Operating Systems (RTOS) and practical exercises with FreeRTOS on ESP32 microntrollers.

An excellent general introduction on RTOS by Renesas: RenesasPresents @ YouTube

After having studied the above video tutorials successfully you are able to answer the following questions:

1. What is a scheduler?
2. What does preemptive mean?
3. What do task, thread, and process mean?
4. What is a semaphore?
5. What is a mutex? How is it implemented?
6. What are message queues used for? How are they implemented?

• Project Home (mainly STM32 and LPC): http://www.chibios.org/dokuwiki/doku.php
• Github: https://github.com/ChibiOS/ChibiOS
• Slides by Giovanni Di Sirio (currently SW architect at STM):
  https://sourceforge.net/p/chibios/svn/HEAD/tree/branches/various/
  The 2012 presentation set is more comprehensive.
• Explained: Multithreading with ChibiOS: http://www.playembedded.org/blog/explanation-multithreading-chibios/

• PORT by William Greiman: ChibiOS/RT for Arduino AVR, SAMD, Due, Teensy 3.x
  Github: https://github.com/greiman/ChRt

This channel describes how to use the RTOS ChibiOS with Arduino.

• Arduino Real Time OS (ChibiOS)
• How to multi-task on an Arduino

Please install the Arduino libraries from the PORT by William Greiman: ChibiOS/RT for Arduino AVR, SAMD, Due, Teensy 3.x
Github: https://github.com/greiman/ChRt

https://www.coursera.org/learn/real-time-systems

“About this course: This course is intended for the Master's student and computer engineer who likes practical programming and problem solving! After completing this course, you will have the knowledge to plan and set-up a real-time system both on paper and in practice.

The course centers around the problem of achieving timing correctness in embedded systems, which means to guarantee that the system reacts within the real-time requirements. Examples of such systems include airbags, emergency breaks, avionics, and also multi-media systems like video playback and QoS in web servers.”

Introduction including list of scheduling strategies: http://projects.laas.fr/simso/doc/introduction.html

Online simulator: http://projects.laas.fr/simso/simso-web/#/configuration

Project home: http://projects.laas.fr/simso/

https://en.wikipedia.org/wiki/Scheduling_(computing)