RTOS

This session is dedicated to Real-Time Operation Systems.

You don't have to submit source files or reports for this sessions. For this session, you will need to log into a PC running Linux. If you are at Eurecom, simply log on a PC of rooms 52 or 53.

I. Introduction to Real-Time and Embedded Systems

1. Open the slides on RTOS


2. Watch the video on an introduction to real-time and embedded systems


3. A real-time system runs faster than usual (i.e. non real-time) systems?
(Help me!) No, it just respects real-time constraints. It is actually common that as a whole, a real-time system is slower than a regular system. Indeed, being sure to respect timing constraints has a processing (and memory) cost. You will see examples of this in the section on exceptions.



4. An elevator controlling system is a real-time system?
(Help me!) I would answer "yes" since an elevator controlling system has to handle a motor which has to be controlled in real-time (speed, acceleration).



5. A real-time application can be executed on every Operating Systems?
(Help me!) It depends. I would say that a soft real-time application can be executed on every Operating System but the quality would probably be better if executed on a RTOS. Hard real-time applications definitely require a RTOS.

II. Fundamentals of RTOS

1. Open the slides on RTOS, second section


2. Watch the video on the fundamentals of RTOS


3. Have a look at the Wikipedia definition for "Reentrancy" and at the Wikipedia definition for Thread safety.
   Then, carefully consider the codes provided in section Example: Neither reentrant nor thread-safe, Thread-safe but not reentrant, Reentrant but not thread-safe, Reentrant and thread-safe. Be sure that you have understood all situations, especially what would happened if isr() were to be called at the indicated line.

III. Exceptions

1. Open the slides RTOS, section on exceptions


2. Watch the video on exceptions in RTOS


3. To be sure you have understood the interest of cutting ISR into two different parts, re-explain the reasons to do this and how this is done with your own words

IV. Timers

1. Open the slides RTOS, section on timers


2. Watch the video on the management of timers in RTOS


3. At the end of this section, you should have understood why timers are inaccurate. Be sure you can explain this inaccuracy with your own words

V. Using Linux for real-time systems

1. Open the slides RTOS, last section


2. Watch the video on Linux capabilities for real-time systems

VI. Robot session

Work on your robot.