Real-Time Systems

The course can be part of the following programmes:

1. Computer Science, Bachelor´s Programme (N1COS)
2. Computer Science, Master's Programme (N2COS)
3. Software Engineering and Management, Master's Programme (N2SOF)
4. Game Design & Technology Master's Programme (N2GDT)
5. Applied Data Science, Master's Programme (N2ADS)

The course is a also a single-subject course at Gothenburg University.

To be eligible to the course, the student should have completed the following courses, or equivalent:

• DIT391 Principles of Concurrent Programming, 7.5 credits
• DIT401 Operating Systems, 7.5 credits
• DIT151 Machine Oriented Programming, 7.5 credits

Applicants must prove knowledge of English: English 6/English level 2 or the equivalent level of an internationally recognized test, for example TOEFL, IELTS.

This course is intended to give basic knowledge about methods for the design and analysis of 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.

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.

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 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.

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.

After completion of the course the student should be able to:

Knowledge and understanding

• 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
• describe the principles and mechanisms used for designing run-time systems and communication networks for real-time applications
• describe how the general principles in real-time programming are implemented in different high-level programming languages

Competence and skills

• construct concurrently-executing tasks (software units) for real-time applications that interface to hardware devices (sensors/actuators)
• apply the basic analysis methods used for verifying the temporal correctness of a set of executing tasks

Judgement and approach

• reflect and argue in writing on ethical aspects regarding the choice of system implementation

The course is organized as a series of lectures and a set of exercise sessions where the programming techniques and theories presented at the lectures are put into practice. The course material is examined by means of a final written exam. In addition, there is a compulsory laboratory assignment in which the students should implement the software for an embedded real-time application running on a hardware system consisting of multiple computer nodes interconnected by a bus network. Apart from the programming of cooperating concurrent tasks with strict timing constraints, the
laboratory assignment also encompasses low-level programming of hardware devices such as timers and network controllers.

Language of instruction: English

The student is evaluated by means of a written exam and a compulsory laboratory assignment.

If a student who has been failed twice for the same examination element wishes to change examiner before the next examination session, such a request is to be granted unless there are specific reasons to the contrary (Chapter 6 Section 22 HF).

If a student has received a certificate of disability study support from the University of Gothenburg with a recommendation of adapted examination and/or adapted forms of assessment, an examiner may decide, if this is consistent with the course’s intended learning outcomes and provided that no unreasonable resources would be needed, to grant the student adapted examination and/or adapted forms of assessment.

If a course has been discontinued or undergone major changes, the student must be offered at least two examination sessions in addition to ordinary examination sessions. These sessions are to be spread over a period of at least one year but no more than two years after the course has been discontinued/changed. The same applies to placement and internship (VFU) except that this is restricted to only one further examination session.

If a student has been notified that they fulfil the requirements for being a student at Riksidrottsuniversitetet (RIU student), to combine elite sports activities with studies, the examiner is entitled to decide on adaptation of examinations if this is done in accordance with the Local rules regarding RIU students at the University of Gothenburg.

Sub-courses

1. Written hall examination, 4.5 credits
   Grading scale: Pass with Distinction (VG), Pass (G) and Fail (U)
2. Laboratory work, 3 credits
   Grading scale: Pass with Distinction (VG), Pass (G) and Fail (U)

The grading scale comprises: Pass with Distinction (VG), Pass (G) and Fail (U).

A Pass grade (G) for the entire course requires at least a Pass grade for all sub-courses. A Pass with Distinction (VG) grade for the entire course requires a VG grade for all sub-courses.

The course is evaluated through meetings both during and after the course between teachers and student representatives. Further, an anonymous questionnaire is used to ensure written information. The outcome of the evaluations serves to improve the course by indication which parts could be added, improved, changed or removed.

The course is a joint course together with Chalmers.

The course replaces the course DIT161, 7.5 credits. The course cannot be included in a degree which contains DIT161. Neither can the course be included in a degree which is based on another degree in which the course DIT161 is included.