SENG408 Real-Time Systems Fundamentals

• SENG408 is a course on the Analysis, Design, and Modelling of Real-Time Systems.
• "Life will not give you what you desire, life will give you what you demand" - Anonymous

Course Outline

• Real-Time System (RTS) Fundamentals
• Hardware for Real-Time Systems
• Real-Time Operating Systems
• Requirement Engineering Methodologies of Embedded RTS
• Software Design Approaches for Embedded RTS
• Tools for Embedded RTS
• Performance Analysis Techniques

Fundamentals of Real-Time Systems

• Definitions of Real-Time System
• Characteristics of Real-Time Systems
• Types of Real-Time Systems
• Applications of Real-Time Embedded Systems

Definitions of Real-Time System

• Defined as systems where correctness depends on both the logical result and the time the result is produced.
• A real-time computing system is a system where the correctness of a computation depends on how it is done and when it's done.
• Logical correctness is based on the correctness of outputs and their timeliness.
• Complexity ranges from simple microcontrollers in automobile cruise control to complex distributed systems like air traffic control.
• Aircraft use accelerometer pulses to determine position, and other systems respond to non-regular events (e.g., overtemperature failure in a nuclear power plant).
• Modern telecommunication systems, automated factories, defense systems, power plants, aircraft, airports, spacecraft, medical instrumentation, supervisory control, data acquisition, people movers, and railroad switching cannot operate without real-time systems.
• A real-time system must satisfy bounded response time constraints to avoid severe consequences.
• A failed system cannot satisfy system requirements.
• Response time is the time between inputs and the availability of associated outputs.
• A real-time system should have predictable fast response to urgent events, high degree of schedulability, and stability under transient overload.
• Early development involves specific tasks like scheduling analysis, performance evaluation, and formal verification of critical timing properties.

Characteristics of Real-Time Systems

• Embedded systems consist of special-purpose computer-based information processing systems performing pre-defined tasks.
• Real-time systems have timing constraints specified in software requirements, where delays can be catastrophic.
• Real-time systems make control decisions based on input data without human intervention.
• Reactive systems are driven by ongoing interaction with their environment.
• Concurrent Processing: Many events need to be processed in parallel with potentially unpredictable order and variable input load.

Types of Real-Time System

• Classified based on hardware platform and deadline.
• There are two major categories of RTS based on hardware platform
• Embedded systems are computer systems for specific control functions, embedded in a larger device with hardware and mechanical parts, which makes updating difficult when failures are discovered.
• Distributed systems consist of autonomous computers connected to coordinate activities and share resources, and are required for dependability, physical constraints, and efficiency, but issues include heterogeneity, timing behavior, and resource management.
• Categorized based on deadline are Hard, Soft and Firm
• Hard Real-Time System: Missing a single deadline may lead to complete or catastrophic system failure
• Soft Real-Time System: Performance is degraded but not destroyed by failure to meet response-time constraints.
• Firm Real-Time System: Missing a few deadlines will not lead to total failure, but missing more than a few may lead to complete or catastrophic system failure.
• All practical systems are ultimately real-time systems.
• Deadlines are based on the underlying physical phenomena of the system under control.
• There are many soft deadlines and few hard deadlines and system designers must determine which deadlines are hard, and schedule processor time accordingly.
• Many utilize global clocks and time-stamping for synchronization, task initiation, and data marking.

Real-Time System Application Domains

• Telecommunication systems
• Automotive control
• Multimedia servers and workstations
• Signal processing systems
• Radar systems
• Consumer electronics
• Process control
• Automated manufacturing systems
• Supervisory control and data acquisition (SCADA) systems
• Electrical utilities
• Semiconductor fabrication systems
• Defense systems
• Avionics
• Air traffic control
• Autonomous navigation systems
• Vehicle control systems
• Transportation and traffic control systems
• Satellite systems
• Aerospace (Flight control, Navigation, Pilot interface)
• Civilian (Automotive systems, Elevator control, Traffic light control)
• Industrial (Automated inspection, Robotic assembly line, Welding control)
• Medical monitors (Intensive care, Magnetic resonance imaging, Remote surgery)
• Multimedia (Console games, Home theaters, Simulators)