News

Staff (contact information)

• Jan Jonsson, Lecturer and Examiner
• Risat Pathan, Course assistant
• Dmitry Knyaginin, Laboratory assistant
• Roger Johansson, Laboratory manager

Course elements

• Sixteen lectures and seven exercises.
• One laboratory assignment, done in groups of at most two people.
• A written exam.

Aim and context

An embedded system is a computer system designed to perform one or a few dedicated functions. It is embedded in the sense that it is part of a complete device, often including electrical hardware and mechanical parts. For reasons of safety and usability, some embedded systems have strict constraints on non-functional behavior such as computational delay and periodicity. Such systems are referred to as real-time systems. Examples of real-time systems are control systems for cars, aircraft and space vehicles as well as computer games and multimedia applications. This course is intended to give basic knowledge about methods for the design and analysis of real-time systems.

After the course the students shall be able to:

• Formulate requirements for embedded systems with strict constraints on computational delay and periodicity.
• Categorize and describe the different layers in a system architecture for embedded real-time systems.
• Construct concurrently-executing tasks (software units) for real-time applications that interface to hardware devices (sensors/actuators).
• Describe the principles and mechanisms used for designing run-time systems and communication networks for real-time applications.
• Apply the basic analysis methods used for verifying the temporal correctness of a set of executing tasks.

Due to the extremely high costs associated with late discovery of problems in embedded systems, it is important to follow a good design methodology during the development of the software and hardware. One means for that is to use a system architecture that offers good component abstractions and facilitates simple interfacing of components. The course gives an overview of some state-of-the-art system architectures being used in the design of embedded systems, for example, EAST-ADL, AUTOSAR and AADL.

The system architecture philosophy dictates that the software of an embedded system is organized into multiple concurrently-executing tasks, where each task (or group of tasks) implements a specific functionality in the system. This approach allows for an intuitive way of decomposing a complex system into smaller software units that are simple to comprehend, implement and maintain. The software environment used in the course is based on the C programming language, enhanced with a software library that provides support for programming of concurrent tasks with timing (delay and periodicity) constraints. To that end, a main objective of the course is to demonstrate how the enhanced C programming language is used for implementing communication/synchronization between tasks, resource management and mutual exclusion. Since other programming languages uses monitors or semaphores to implement these functions, the course also contains a presentation of such techniques. In addition, the course demonstrates how to use low-level programming in C to implement interrupt-driven interaction with hardware devices. To demonstrate the general principles in real-time programming, the course also gives examples of how these techniques are implemented in other programming languages, such as Ada and Java.

In order to execute a program containing concurrent tasks there is a run-time system (real-time kernel) that distributes the available capacity of the microprocessor(s) among the tasks. The course shows how a simple run-time system is organized. The run-time system determines the order of execution for the tasks by means of a scheduling algorithm. To that end, the course presents techniques based on cyclic time-table based scheduling as well as scheduling techniques using static or dynamic task priorities. In addition, protocols for the management of shared hardware and software resources are presented. Since many contemporary real-time applications are distributed over multiple computer nodes, the course also presents topologies and medium access mechanisms for some commonly-used communication networks.

The real-time kernel determines the order of execution for the processes by means of a scheduling algorithm. To that end, the course presents techniques based on cyclic time-table based scheduling as well as scheduling techniques using static or dynamic process priorities. In addition, protocols for the management of shared hardware and software resources are presented.

In real-time systems, where tasks have strict timing constraints, it is necessary to make a pre-run-time analysis of the system schedulability. The course presents three different analysis methods for systems that schedule tasks using static or dynamic priorities: utilization-based analysis, response-time analysis, and processor-demand analysis. In conjunction with this, the course also gives an account on how to derive the maximum resource requirement (worst-case execution time) of a task.

Context

Important Dates

Lectures

The course is organized as a series of lectures where fundamental theories and concepts are presented. Lectures are given at two occasions per week (except study week 1, 2 and 3 where there are extra lectures on Wednesday):

As a complement to the lectures, there will be exercise sessions on the specific topics covered during the main lectures. At each session, a course assistant gives a mini lecture on selected parts of the course contents, and also discusses selected problems from the exercise compendium. The remaining time is for discussing solutions to the selected problems or the laboratory assignment. Exercise sessions are offered on one occasion per week:

Preliminary schedule: TimeEdit

Detailed information on the lectures will appear here.

Course book

Alan Burns and Andy Wellings, Real-Time Systems and Programming Languages, 4th edition, Addison-Wesley, 2009, ISBN 978-0-321-41745-9

Course Evaluation

For the purpose of course evaluation, we ask volunteers to act as student representatives. Their role includes giving the teachers some feedback on the course. Please send them an email if you have comments or suggestions for improvements regarding the course.

The student representatives are:

Minutes from mid-quarter course evaluation meeting can be found here.

Chalmers central instructions on course evaluation