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Universidade Técnica de Lisboa - Instituto Superior Técnico Departamento de Engenharia Electrotécnica e de Computadores

Área Científica de Computadores

Lisboa, Portugal2013

MEE

Sistemas EmbebidosEmbedded Systems

Rui Manuel Rodrigues Rocharui.rocha@lx.it.pt

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Introduction

Goals

Organization

Program

Assessment

Bibliography2

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Goals

To study the architectures, systems and technologies of embedded systems capable of probing the real-world and interacting with it.

Improve students’ culture on computer architectures, operating systems and interfacing, with particular emphasis on real-time systems.

The most profound technologies are those that disappear. They weave themselves into the fabric of everyday life until they are indistinguishable from it.

Mark Weiser in Scientific American, 1991

Computers are not primarily used for solving mathematical problems or data processing, but instead are components in complex systems.

Terry Winograd in Communication of the ACM, 1979

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Organization

L e c t u r e s ( P r o f . R u i R o c h a )

S c h e d u l e : Tuesday (14:10-15:30) ; Wednesdays (14:10-15:30)

L a b s ( P r o f . C a r l o s A l m e i d a & R u i R o c h a )L a b s e s s i o n s - 3 h o u r s ( f o r t n i g h t l y ) 1 p r o j e c t - e a c h g r o u p ( 2 ) w i l l t a c k l e a d i f f e r e n t p r o b l e m

P a r t 1 - h a n d l i n g t h e h a r d w a r e w / b a s i c s o f t w a r eP a r t 2 - u s i n g a R T O S

S u p p o r tb y e - m a i l : r u i . r o c h a @ l x . i t . p tO f f i c e : T B A o n t h e c o u r s e w e b s i t e

I n f o r m a t i o n s ( w e b )4

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Programme

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Basics of Embedded Computing Introduction

Embedded & Real-time Systems characterization Fallacies and Pitfalls, Challenges

CPUs Typical CPUs ISA architectures

System’s ArchitectureMemory, Bus, I/O

Development Platforms & tools

Multiprogramming and OSMultitaskingOperating Systems: structure, main functions, ... SchedulingSynchronization and IPCMechanisms, typical primitives, examples

FreeRTOS Task managementSynch. & IPCInterrupts and Device HandlersExamples of primitivesUse cases examples

Real-time issuesscheduling, priority inversion

Design methodologiesAbstraction levels, specs, design approaches, integrationExamples

Networked embedded systems Comm. in Embedded Systems

Ethernet, CAN, ZigbeeMain issues: networking, power management, ...Main protocols: data-link, time-synch, ...

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Lectures and assignments schedule

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See https://fenix.ist.utl.pt/disciplinas/semb/

2012-2013/1-semestre

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Assessment

Final Exam (minimum grade 8,5)

1st Period - Jan, 11 2014

2nd Period - Feb, 1 2014

Lab (minimum grade 9,5)

Project delivery

Part I - Nov, 8 2013; Part II - Dec, 20 2013

Oral assessment - Jan, 3 & 4 2014

Final Grade

NF = 0,5*EF + 0,5*Lab

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Bibliography

Main Textbooks Wayne Wolf; Computers as Components: principles of embedded computing system design, Morgan Kaufman, 2000.

Richard Berry; Using the FreeRTOS Real Time Kernel, FreeRTOS 2009. http://shop.freertos.org/RTOS_primer_books_and_manual_s/1819.htm

Complementary TextbooksRichard Zurawski (ed.); Embedded Systems Handbook, 2nd Ed., Vol.I - Embedded Systems Design and Verification, CRC Press, 2009

Richard Zurawski (ed.); Embedded Systems Handbook, 2nd Ed., Vol.II - Networked Embedded Systems, CRC Press, 2009

Phillip Laplante; Real-time systems design and analysis: an engineer's handbook, IEEE Press, 1993.

Michael Barr; Programming Embedded Systems in C and C++. O'Reilly & Associates, Inc, 1999.

Other documentsManuals and Tutorials … see the website for some references.

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Maths is not everything

Embedded & Real-time Systems

Introductory Notes:

Embedded SystemsReal-time Systems

Real-time Systems’ CategoriesPitfalls and Fallacies

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Embedded & Real-time SystemsDefinition of an Embedded System

The “computer” is a “component” of a more complex system.

This system is not designed for a generic utilization but rather for a special purpose.

The “computer system” physically interact with the real world.

RTSs have requirements on the timing of these interactions.

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Embedded & Real-time SystemsReal-time Systems

A Real-time System:

Produces results that are correct both in logical and time domains

a system is said to have real-time properties if its results are logically correct and were produced at the right time.

a correct response given out of its expected time is considered incorrect from a real-time point of view!

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Embedded & Real-time SystemsReal-time System’s Categories

Hard Real-time System:Every response respects a strict time specification

otherwise it represents a system failure.Example: car airbag

Firm Real-time System:Infrequent deadline misses are tolerable, but may degrade the system's quality of service.

The usefulness of a result is zero after its deadline.Example: video game, non critical industrial process

Soft Real-time SystemMost of its responses fall into a given time interval specification

but not meeting this deadline does not represents a system failure -> occasional timing failures are acceptable

Example: travel booking systems

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Embedded & Real-time SystemsPitfalls and Fallacies

Real-time means ad-hoc approaches

Real-time is equivalent to speed

Technology will eventually solve real-time problems

Real-time systems must use Assembly as the programming language

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