ECE3196_Chapter1 , embeded systems

ECE3196 Embedded System Design

Trimester 2, 2013/2014

Chapter 1: Overview of Embedded System

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ECE3196 – Chapter 1

Overview of Embedded System

Definition of embedded system

Application areas

Characteristics of embedded system

Challenges of embedded system

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Definition

Definition of embedded system

• Embedded system is a combination of hardware and software (computer system), designed to perform specific function(s).

Question:

• Name a few embedded system products that you use frequently.

• Can a notebook or smartphone be consider as a part of an embedded system?

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Overview

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Execution environment

I/OMemory

Processor

I/O

Timer

Microcontroller

System

Overview of a simple embedded system

Overview

Embedded systems and ubiquitous computing

• Not all embedded systems have all of the characteristics of embedded system.

• Most of the characteristics of embedded system can be found in ubiquitous computing. The key goal of ubiquitous computing is to make information available anytime, anywhere.

5Influence of embedded system in ubiquitous computing

Application Areas

Application areas (samples)

• Automotive

• Air travel industry

• Telecommunication & networking

• Games

• Medical & healthcare

• Security

• Consumer electronics

• Buildings

• Robotics

• Wearable technology

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Application AreasAutomotive industry

Engine control

Body electronics- Air conditioning- Automatic lighting

Driver information systems-GPS-Dashboard display- Audio/video control- Lane departure warning

Chassis-Breaking system-Electronic power steering

Safety-Airbags-TPMS

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Application Areas

Input interface Output interface

Weight sensor

Warning lamp

Interconnection network

Block diagram of an airbag system

Processor ROM RAM

Acceleration sensors

Airbag squibs

Buckle switch

Application Areas

Air travel industry

Flight control systems

Pilot information systems

Anti-collision system

Air traffic control

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Application Areas


Altimeter Visual indicator


Block diagram of an auto-pilot system

Processor ROM RAM

Acceleration sensors

Various servos

Pressure sensor

Activation keys

GPS

Audio indicator

Elevator

Aileron

Rudder

Flap

Engine control

Speed brake

Landing gear

Application Areas

Telecommunication & networking

Mobile phoneServer

Smart phone

GPS

Tablets

Base station

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Application Areas


Keypad & buttons LCD

display


Block diagram of a simple mobile phone

Processor ROM RAM

Speaker

Microphone

Receiver

Transmitter

Application Areas

Games

Hardrive

Wireless controller

Sensor

Console

3D screen Sensors Controller

Memory13

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Application Areas


Depth sensor

Input keys

Television


Block diagram of a touchless play station

Processor ROM RAM

Application Areas

Medical & healthcare

Medical imaging

Artificial eye

Pedometer

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Application Areas

Microcontroller


Inertial sensor


Block diagram of a pedometer

LCD display

BuzzerInput buttons

Backlight

Application Areas

Authentication

Military applications

Security

Missile launcher

Submarine

Intelligent pen Door security 17

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Application Areas


Input keys Fingerprint reader

Magnetic door lock

Alarm


Block diagram of a door security system

Processor ROM RAM

Application Areas

Consumer electronics

TelevisionWashing machine

Camera

ComputerMicrowave oven

Sewing machine

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Application Areas

Microcontroller


Input keys Door open Magnetron

Display

Fan

Light

Speaker


Block diagram of a microwave oven

Application Areas

Smart buildings

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Application Areas

Processor ROM RAM


Input switch Door open

Lighting brightness


Block diagram of energy efficient lighting

Light sensor Motion sensor

Home Energy Manager

LCD display

Application Areas

Process control

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Application Areas

Microcontroller


Sensor 1 Input keys

Valve 1


Block diagram of a fluid mixture system

Sensor 2 Sensor 3

Station controller

Valve 2

Valve 2

LCD display

Application Areas

Robotics

Domestic

Rehabilitation

Companion

Delivery25

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Application Areas

Processor ROM RAM


Camera


Block diagram of a companion robot

Actuators SpeakerProximity sensor

Modem

Switches Lights

Application Areas

Wearable technology

Smart watch

Google glass

Mind control

Virtual touchscreen

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Application Areas

Processor ROM RAM


Camera


Block diagram of a virtual touchscreen

Mini projector

BuzzerInput keys

Modem

Characteristics of Embedded Systems Dependable Efficient Dedicated

Real-time constraint Connected to the environment

Hybrid system Reactive

Characteristics

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Dependable:•Reliability R(t) = Reliability is the probability that a system

will not fail at time t.•Maintainability M(d) = Maintainability is the probability that

a failing system can be repaired within a certain time-frame.•Availability: Availability is the probability that the system is

available.•Safety: No harm to be caused by a failing system.•Security: Confidential data remains confidential and that

authentic communication is guaranteed.

Characteristics

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t

t1st phase 2nd phase 3rd phase

Typical behavior of hardware systems ("bathtub curve"). Commonly use characterize reliability of a system

Characteristics

Reliability

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Characteristics

Hardware Reliability

• The probability that a component fails some time in the interval [0,t] is assumed to the PDF of the component lifetime at time, t.

• Widely used model for PDF of the component lifetime is given by

F(t) = 1 – exp(-λt)

• A system can consist of more than one component.

• Let Ri(t) be the reliability of component Ci over time interval [0,t] and Fi (t) be the probability that Ci fails at the same time interval. Hence,

Ri (t) = 1 – Fi (t)

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Characteristics

Hardware Reliability examples

Assumptions:

• Fault latency is zero

• Any failure is permanent and any faulty processor is immediately identified and disconnected from the system, never repaired and reconnected.

• Failures are all independent

Example 1: Series-connected

• System fails if any of the component fails

R(t) = ∏Ri(t) C1 C2 C3N

i=0

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Characteristics

Example 1: Parallel-connected

• System fails if all of the component fails

R(t) = 1 - ∏(1 - Ri(t))C1

C2

C3

N

i=0

operational

faulty

MTTFMTTRMTBF

t

MTTF = mean time to failureMTTR = mean time to repair

(average over repair times using distribution M(d))MTBF = mean time between failures = MTTF + MTTR

MTBFMTTF)(lim

tAA

t

Characteristics

Availability

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Dependable• Even perfectly designed systems can fail if the assumptions

about the workload and possible errors turn out to be wrong.• Making the system dependable must not be an after-thought, it

must be considered from the very beginning.

Characteristics

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Efficient

Energy efficient

Code-size efficient(especially for systems on a chip)

Run-time efficient

Weight efficient

Cost efficient

Dedicated towards a certain applicationKnowledge about behavior at design time can be used to minimize resources and to maximize robustness

Dedicated user interface

Characteristics

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Real-time constraints– A real-time system must react to stimuli from the controlled object (or the operator) within the time interval dictated by the environment.– For real-time systems, right answers arriving too late are wrong.

Hard ES vs. Soft ES–“A real-time constraint is called hard, if not meeting that constraint could result in a catastrophe”[Kopetz, 1997].– All other time-constraints are called soft.

Characteristics

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Frequently connected to physical environment through sensors and actuators.

Hybrid systems(analog + digital parts).

Embedded systems are reactive systems typically:

“A reactive system is one which is in continual interaction with

its environment and executes at a pace determined by that

environment” [Bergé, 1995]

Characteristics

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Challenges for Embedded Hardware

Lack of flexibility (changing standards).

Mask cost for specialized HW becomes very expensive.

Competitive market: Fast improvement in products capability to satisfy the consumer.

Shrinking in size.

Speed.

Human-machine interface.

Power consumption.

On-chip memory.

Challenges

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Challenges for implementation in software

• If embedded systems will be implemented mostly in software, then why don‘t we just use what software engineers have come up with?

Challenges

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• Exponential increase in software complexity- Increase in code sizeIn some areas code size is doubling every 9 months [ST Microelectronics, Medea Workshop, Fall 2003]

- Software development course. (license, expertise, training)... > 70% of the development cost for complex systems such as automotive electronics and communication systems are due to software development[A. Sangiovanni-Vincentelli, 1999]

Challenges

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Dynamic environments - For a typical embedded system, it is in continual interaction with its environment and executes at a pace determined by that environment.

Capture the required behaviour! - it is not a trivial task to capture the required behavior of the software from the problem to be solved. Wrong assumption about the problem may lead to wrong specifications.

Efficient translation of specifications into implementations!

Challenges

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Validate specifications - Even if the specifications are correct, we still face the problem of validating and translating the specifications into efficient implementations.

As most of the embedded systems are real-time system, embedded software developers also face the problems of how to verify that the developed system meets real-time requirement.

It is not easy to ensure that the testing procedures will not violate the timing constraints.

Challenges

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It is not sufficient to consider ES (Embedded System)just as a special case of software engineering

CS EE

EE (Electrical and Electronics) knowledge must be available, walls between EE and CS (Computer Science) must be torn down

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Challenges

Other Challenges

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Open systems – Many people are given access to technology and are encouraged to tinker and enhance it. Software innovation rely on large number of tinkering programmers.

Internet access – Popularity matters.

Net neutrality – Latency sensitive vs. latency insensitive traffic

Privacy – The sum of human knowledge can be available at our fingertips via Internet connected devices.

Successful commercialization – At macro scale, new technologies are ultimately funded via the displacement of existing technology that they render obsolete.

Energy – Supply vs. demand

“... the New York Times has estimated that the averageAmerican comes into contact with about 60 micro-processors every day....” [Camposano, 1996]

“...By 2013, the number of devices connected to the internet will reach one trillion – up from 500 million in 2007. We’ve heading into Internet of Things.”[Cisco CTO Padmasree Warrior, 2010]

We may not see them but they are all around us. We depend on them more than we realized it.

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Importance of Embedded System

ECE3196 – Chapter 1

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References:1. Peter Marwedel, "Embedded System Design", Springer, 2ndedition, 2011.

2. Daniel D. Gajski et.al, “Embedded System Design, Modeling, Synthesis and Verification”, Springer, 2009.

3. Carl Hamacher et. Al, “ Computer Organization and Embedded System”, McGraw Hill International Edition 6th edition, 2012

4. Peter Barry and Patrick Crowley, “ Modern Embedded Computing –Designing Connected, Pervasive, Media-Rich System”, Morgan Kaufmann, 2012.

5. Graham Leedham and Kian-Tian Seow, “Embedded Real-Time Systems: Introductory Concepts and Tools”, Person Prentice Hall, 2005.

6. Various internet sources.

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