Presentation is loading. Please wait.

Presentation is loading. Please wait.

Real-Time Systems – The big Picture

Similar presentations

Presentation on theme: "Real-Time Systems – The big Picture"— Presentation transcript:

1 Real-Time Systems – The big Picture
ITV Real-Time Systems Anders P. Ravn Aalborg University February 2009

2 Literature Alan Burns and Andy Wellings: Real-Time Systems:
Ada 95, Real-Time Java and Real-Time POSIX (B & W) Acknowledgement: Some slides are adapted from their Teaching Aids

3 Prerequisites Basic understanding of C and Java
Basic understanding of Computer Architectures. Basic understanding of Operating Systems

4 Course Aims Understanding of the broad concepts
Practical understanding for industry To stimulate research interest

5 What is a real-time system?
A real-time system is a computerized system that must respond to externally generated input within specified time bounds The computer is a component in a larger engineering system - EMBEDDED COMPUTER SYSTEM 99% of all processors are for the embedded systems market

6 A simple fluid control system
Pipe Interface Input flow reading Flow meter Processing Valve Output valve angle Computer

7 The Control Task Periodic: OR Sporadic: LOOP LOOP wait_until(t)
read_sensor; compute; write_actuator; t = t+T; END LOOP wait_event; read_sensor; compute; write_actuator; END

8 The R-T Constraint The activation times Si and response times Ri
satisfy: Ri – Si  D – the deadline Si+1 – Si = T – the period

9 Terminology Hard real-time Soft real-time Firm real-time
Value of response Time D D may be missed occasionally

10 A Typical Embedded System
Real-Time Clock Algorithms for Digital Control Engineering System Interface Data Logging Remote Monitoring System Database Data Retrieval and Display Display Devices Operator’s Console Operator Interface Real-Time Computer

11 A Simple Embedded System
Thermocouples ADC Pressure Transducer T S P Switch ADC Heater Screen DAC Pump/Valve Keep the temperature and pressure of some chemical process within well-defined limits

12 Implementation See Example 7.6 in Other Material

13 RTS Design Essentially:
Specification of a collection of periodic and sporadic tasks. Tasks may share resources, but must not block explicitly. Formalisms: UML-RT RT- HOOD

14 RTS Implementation Language characteristics: Security Readability
Flexibility Simplicity Portability Efficiency

15 Validation Verification Testing Simulation Model
Prototype with Test harness Real System ON

16 Characteristics of a RTS
Timing Constraints Dependability Requirements Concurrent control of separate components Facilities to interact with special purpose hardware

Download ppt "Real-Time Systems – The big Picture"

Similar presentations

Ads by Google