SE-3910Real-time Systems

• Week 1, Class 2– Fine Print– Web page available– Review Quiz 0– What is a Real-Time Embedded System?

• Embedded & Real-Time Systems• Microcontrollers vs. Microprocessors• Impact

SE-3910 - Dr. Josiah YoderSlide style: Dr. Hornick

Much Material: Dr. Schilling, Some from Dr. Hornick, etc. 1

CPU Layout (1)

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CPU Layout (2)

SE-1021Dr. Josiah Yoder

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Terminology

• Definition– A brief description of a word’s use

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Terminology

• Real-Time– responding as rapidly as required by the user

or the process being controlled. - Random House Dictionary

(Abbrev.)

• Embedded System– A combination of hardware & software to perform a specific

function-Dr. Schilling’s slides

– Part of a larger system – the “computational engine”

– Often real-timeSE-1021

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SE-1021Dr. Josiah Yoder

Slide style: Dr. HornickSlide copied from Dr. Schilling’s Slides

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TABLE I, TABLE II

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What is a system?

SystemA mapping from a set of inputs to outputs

SE-3910 - Dr. Josiah YoderSlide style: Dr. Hornick

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Example: Weather Monitor

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Real-Time SystemTerminology

• Soft– Not destroyed by failure to meet response time

• Hard– Destroyed by failure to meet a single deadline

• Firm– Destroyed by failure to meet multiple deadlines

SE-3910 - Dr. Josiah YoderSlide style: Dr. Hornick

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Virtual Plant Tour

• Stamping– http://www.youtube.com/watch?v=bYCc3toOHdc

• Vision– http://www.youtube.com/watch?v=QXbpxHeeBA

E

SE-3910 - Dr. Josiah YoderSlide style: Dr. Hornick

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Got this far on first day

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Discussion• On your own: Write which kind of real-time system is being used• With your partner, discuss & fill in the explanations

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System Classification Explanation

Video Surveillance System for Car Dealership

Laser welding robot to construct car frames

2 player air hockey game on game console

• Event– A jump in the program counter

• Synchronous– Predicatable. Scheduled. In sync with other events

• Asynchronous– Unpredictable. Unscheduled. External requests

• Aperiodic – No fixed period, asynchronous• Sporadic – Extremely infrequent and aperiodic• Punctual – Neither early nor late

SE-3910 - Dr. Josiah YoderSlide style: Dr. Hornick

Much Material: Dr. Schilling14

Digibot Circuitry

• A deterministic system

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Five Misconceptions(paraphrased from Laplante and

Ovaske)• Real-time Systems are fast• All you need is

– a real-time OS– a rate-monotonic scheduler– lots of scheduling theory

• We’ve figured out how to make real-time systems

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