CM0508 Real-time operating systems and concurrency

RTOS Image This module introduces the application and implementation of real-time operating systems and the use of concurrency in programming small embedded systems. It presents fundamental concepts: processes, communication and synchronisation, and illustrates their implementation using a modern, standards-compliant RTOS. Students are given the opportunity to apply an RTOS in their own programs to solve a variety of problems.

Lectures are the main vehicle for introducing fundamental concepts and principles and for providing context and motivation. Students will be expected to prepare for lecture topics and deepen their understanding of course material by studying course texts and technical literature. Seminars and laboratory sessions support the lecture programme by providing students with opportunities to identify and apply appropriate techniques for the application and implementation of a variety of RTOS services.

Formative assessment will be provided in the form of small weekly exercises, mainly practical in nature and involving programming. Summative assessment is by way of course work undertaken in the last 4/5 weeks of the module. Students will be required to implement a simple embedded application, making use of a real-time operating system, and to report on issues raised by their work.

The principles and techniques taught in this module complement those treated in CM0506 Small Embedded Systems and are used extensively in the level 6 modules CM0605 Embedded Systems Engineering and CM0034 Industrial Case Project.

Module Team

Module tutor
Michael Brockway
Lecturer
David Kendall

Teaching Arrangements

Lecture Mon 11.00 - 12.00 EB A108
Lab/Seminar Mon 17.00 - 18.00 PB F1
Lab/Seminar Thu 13.00 - 14.00 PB F1

You should attend the lecture session and one of the lab/seminar sessions every week.

Synopsis

The aim of this module is to provide students with an understanding of the application and implementation of real-time operating systems. Students will be able to develop small, embedded systems using a variety of RTOS services, including multi-tasking, synchronisation, communication and timing. A practical approach is taken throughout and assessment is by course work.

On completion of this module, students will be able to:

  1. Describe the architecture of a typical RTOS, explain its services and evaluate the advantages and disadvantages of its use in a variety of embedded system scenarios.
  2. Discuss the task model and scheduling services provided by an RTOS and reason informally about the behaviour of a multi-tasking system under a variety of scheduling algorithms.
  3. Explain the application and implementation of basic RTOS services for task synchronisation, inter-task communication and event timing.
  4. Apply their knowledge of task management, synchronisation, communication and timing services in designing and building a small multi-tasking embedded system that makes use of a simple RTOS.

Teaching Plan

The following is a provisional guide to the organisation of this part of the module for this year. These arrangements are subject to change during the course of the module.

Week W/c Lecture Practical
1 27-Sep Introduction to real-time, operating systems, and real-time operating systems. [Slides] Introduction/review of development tools/environment. A simple device driver 1: LED driver. C programming exercises. [Lab]
2 04-Oct The process model. Interrupts and Interrupt Service Routines (ISR). [Slides] A simple device driver 2: Joystick driver. C programming exercises. [Lab]
3 11-Oct Interrupts, Vectored Interrupt Controller (VIC), ISR implementation [Slides] A timer interrupt and timer ISR. [Lab]
4 18-Oct Introduction to ucOS-II: multi-tasking, delays [Slides] Task management and delays in uC/OS-II [Lab]
5 25-Oct Shared variable IPC; interference; race conditions [Slides] More task managment and delay in uC/OS-II [Lab]
6 01-Nov Mutual exclusion algorithms: Dekker, Peterson. Deadlock. Starvation. [Slides] C programming problems [Lab]
7 08-Nov Semaphores and mutexes. [Slides] Introduction to the assignment. Semaphores/mutexes lab. [Lab]
8 15-Nov Event flags, mailboxes and message queues. [Slides] Solving communication and synchronisation problems with event flags, mailboxes and message queues. [Lab]
9 22-Nov The problem of priority inversion and some solutions. [Slides] Assignment lab/surgery
10 29-Nov Memory management [Slides] Assignment lab/surgery
11 06-Dec Review [Slides] Assignment lab/surgery
12 13-Dec Assignment surgery Assignment lab/surgery

Note

In addition to the taught sessions, you are expected to undertake independent and directed learning. On average, you should be spending about 8 hours per week on this module.

Assessment

Summative assessment comprises:

  • a single course work assignment undertaken in the last 4/5 weeks of the module; students will be required to implement a simple embedded application, making use of a real-time operating system, and to report on issues raised by their work. [Assignment Specification]

Formative assessment comprises a variety of theoretical and practical exercises with opportunities for discussion with tutors and colleagues.

Feedback on formative assessment will be given during the seminar and laboratory sessions. Additionally the eLearning Portal will be used for more formal feedback on summative assessment.

Recommended Reading

There is no essential textbook for this module. [LAB08] gives full details of the uCOS-II RTOS used in the module but is too expensive to recommend for individual purchase. The other recommended books and papers give useful information on parts of the syllabus only.

  • Books
    • [DOW08]Downey, A., The Little Book of Semaphores (Local copy), Green Tea Press, 2002
      A free text book by Allen Downey that introduces a variety of interesting synchronisation problems and their solution using semaphores.
    • [LAB02]Labrosse, J., MicroC/OS-II The Real-Time Kernel (2nd edition), Newnes, 2002
      A good textbook that gives a detailed account of (an earlier version of) the real-time operating system used in this module. Too expensive to buy outright but it would be a good idea to have access to it. The library has nine copies. It might cost about a tenner each between 3 or 4 of you to get hold of a copy.
    • [WOL08]Wolf, W., Computers as Components: Principles of Embedded Computing System Design, Morgan Kaufmann, 2008
      Nice overview of interrupts in Chapter 3 and of RTOS in Chapter 6.
  • Papers

Resources