1. Universidade Técnica de Lisboa - Instituto Superior Técnico
Departamento de Engenharia Electrotécnica e de Computadores
Área Científica de Computadores
Sistemas Embebidos
Embedded Systems
Rui Manuel Rodrigues Rocha
rui.rocha@lx.it.pt
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Lisboa, Portugal
2013
MEE
Introduction
Goals
Organization
Program
Assessment
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Bibliography

2. Goals
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
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
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
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systems.
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Organization
L e ctu re s
( Pro f . Ru i Ro cha)
S ch e du l e : Tuesday (14:10-15:30); Wednesdays (14:10-15:30)
L abs
( Pro f . Carlo s Alme ida & Ru i Ro cha)
L ab se ssio ns - 3 ho u rs ( f o r tnightly )
1 project - each grou p ( 2) w ill tackle a different problem
P ar t 1 - h andl ing t he hardware w/ bas ic s oftw ar e
P ar t 2 - u sing a RTOS
Support
by e - m ail: ru i.rocha@lx .it .pt
O f f ice : TBA on the cou rse w ebsite
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I n f o r m a t i o n s ( w e b)

3. Programme
Basics of Embedded Computing
Introduction
FreeRTOS
Embedded & Real-time Systems
characterization
Task management
Fallacies and Pitfalls, Challenges
Interrupts and Device Handlers
Examples of primitives
CPUs
Typical CPUs ISA architectures
System’s Architecture
Memory, Bus, I/O
Development Platforms & tools
Multiprogramming and OS
Operating Systems: structure, main
functions, ...
Scheduling
Synchronization and IPC
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Use cases examples
Real-time issues
scheduling, priority inversion
Design methodologies
Abstraction levels, specs, design
approaches, integration
Examples
Multitasking
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Synch. & IPC
Mechanisms, typical primitives,
examples
Networked embedded systems
Comm. in Embedded Systems
Ethernet, CAN, Zigbee
Main issues: networking, power
management, ...
Main protocols: data-link, timesynch, ...
Lectures and assignments schedule
See
https://fenix.ist.utl.pt/disciplinas/semb/
2012-2013/1-semestre
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4. 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 Textbooks
Richard 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 documents
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Manuals and Tutorials … see the website for some references.

5. Maths is not everything
Embedded & Real-time Systems
Introductory Notes:
Embedded Systems
Real-time Systems
Real-time Systems’ Categories
Pitfalls and Fallacies
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Embedded & Real-time Systems
Definition 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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6. Embedded & Real-time Systems
Real-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 Systems
Real-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 System
Most 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
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Example: travel booking systems

7. Embedded & Real-time Systems
Pitfalls and Fallacies
Real-time means ad-hoc approaches
Real-time is equivalent to speed
Technology will eventually solve realtime problems
Real-time systems must use Assembly
as the programming language
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