Sistem Embedded (Introduction)

7/27/2019 Sistem Embedded (Introduction)

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Introduction toEmbedded Systems Dr. Pedro Mejia Alvarez

Introduction

to

Embedded Systems


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Introduction

What are embedded systems?

What makes them different?

Real time operation

Many sets of constraints on designs

Challenges in embedded computingsystem design.

Design methodologies.


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Definition

Embedded system: any device that includes a

programmable computer but is not itself a general-

purpose computer.

Computer purchased as part of some other piece ofequipment

Typically dedicated software (may be user- customizable)

Often replaces previously electromechanical components

Often no real keyboard Often limited display or no general- purpose display device: dont

need all the general-purpose bells and whistles.


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Introduction to

Embedded Systems Dr. Pedro Mejia Alvarez

What is an embedded system


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Examples

Office systems and

mobile equipmentBuilding systems Manufacturing and

Process Control

Answering machines

Copiers

Faxes

Laptops and notebooks

Mobile Telephones

PDAs, Personal organisers

Still and video cameras

Telephone systems

Time recording systemsPrinter

Microwave

Air conditioning

Backup lighting and

generators

Building managementsystems

CTV systems

Fire Control systems

Heating and ventilating

systems

Lifts, elevators, escalators

Lighting systems

Security systems

Security cameras

Sprinkler systems

Automated factories

Bottling plants

Energy control systems

Manufacturing plants

Nuclear power stations

Oil refineries and related

storage facilities

Power grid systems

Power stations

Robots

Switching systems

Water and sewage systems


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Examples

Transport Communications Other equipment

Aeroplanes

Trains

Buses

Marine craft

Jetties

Automobiles

Air Traffic Control

Signalling Systems

Radar Systems

Traffic LightsTicketing machines

Speed cameras,

Radar speed

detectors

Telephone systems

Cable systems

Telephone switches

Satellites

Global Positioning

System

Automated teller systems

Credit card systems

Medical Imaging equipment

Domestic Central Heating control

VCRs


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Introduction to


Automotive embedded

systems

Todays high-end automobile may have100 microprocessors:

4-bit microcontroller checks seat belt;microcontrollers run dashboard devices;

16/32-bit microprocessor controls engine.


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BMW 850i brake and

stability control system

Anti-lock brake system (ABS): pumpsbrakes to reduce skidding.

Automatic stability control (ASC+T):controls engine to improve stability.

ABS and ASC+T communicate.

ABS was introduced first---needed tointerface to existing ABS module.


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BMW 850i, contd.

brake

sensor

brake

sensor

brake

sensor

brake

sensor

ABShydraulic

pump


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Embedded systems rule

the market place

80 Million PCs vs. 3Billion EmbeddedCPUs Annually

Embedded market growing; PC marketmostly saturated


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Why are embedded systems

different from desktop computers ?


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Four General Embedded

Systems Types

General Computing

Applications similar to desktop computing, but in an embedded package

Video games, set- top boxes, wearable computers, automatic tellers

Control Systems

Closed- loop feedback control of real- time system Vehicle engines, chemical processes, nuclear power, flight control

Signal Processing

Computations involving large data streams

Radar, Sonar, video compression

Communication & Networking

Switching and information transmission

Telephone system, Internet


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Characteristics of an

embedded system

Real-Time Operation

Reactive: computations must occur in response to external events

Correctness is partially a function of time

Small Size, Low Weight

Hand- held electronics and Transportation applications -- weight costsmoneyLow Power

Battery power for 8+ hours (laptops often last only 2 hours)

Harsh environment

Heat, vibration, shock, power fluctuations, RF interference, lightning,

corrosionSafety- critical operation

Must function correctly and Must notfunction in correctly

Extreme cost sensitivity

$. 05 adds up over 1,000, 000 units


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Embedding a computer

CPU

mem

input

output analog

analog

embedded

computer


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Why use microprocessors?

Microprocessors simplify the design of families ofproducts.

Microprocessors are often very efficient: can use

same logic to perform many different functions, butMicroprocessors use much more logic to implementa function than does custom logic.

Alternatives: field-programmable gate arrays

(FPGAs), ASICs, custom logic, etc.What about MicroControllers or DSPs.

Custom logic is a clear winner for low powerdevices.


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An Embedded Control

System Designers View


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A Customer View


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Design teams

Often designed by a small team ofdesigners.

Often must meet tight deadlines.6 month market window is common.

Cant miss back-to-school window for

calculator.


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Challenges in embedded

system design

How much hardware do we need?

How big is the CPU? Memory?

How do we meet our deadlines?Faster hardware or cleverer software?

How do we minimize power?

Turn off unnecessary logic? Reduce memoryaccesses?


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Challenges, etc.

Does it really work?

Is the specification correct?

Does the implementation meet the spec?How do we test for real-time characteristics?

How do we test on real data?

How do we work on the system?Observability, controllability?

What is our development platform?


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Embedded System Designer Skill Set

Appreciation for multi- disciplinary nature of design

Both hardware & software skills

Understanding of engineering beyond digital logic

Ability to take a project from specification through production

Communication & teamwork skills Work with other disciplines, manufacturing, marketing

Work with customers to understand the real problem being solved

Make a good presentation; even better-- write trade rag articles

And, by the way, technical skills too

Low level: Microcontrollers, FPGA/ ASIC, assembly language, A/ D, D/ A High level: Object- oriented Design, C/ C++, Real Time Operating Systems

Meta level: Creative solutions to highly constrained problems

Likely in the future: Unified Modeling Language, embedded networks

Uncertain future: Java, Windows CE


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Design methodologies

A procedure for designing a system.

Understanding your methodology helps

you ensure you didnt skip anything.Compilers, software engineering tools,

computer-aided design (CAD) tools, etc.,

can be used to:help automate methodology steps;

keep track of the methodology itself.


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Design goals

Performance.

Overall speed, deadlines.

Functionality and user interface.Manufacturing cost.

Power consumption.

Other requirements (physical size, etc.)


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Levels of abstraction

requirements

specification

architecture

component

design

system

integration


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Our requirements form

name

purpose

inputs

outputsfunctions

performance

manufacturing cost

powerphysical size/weight


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Example: GPS moving map

requirements

Moving mapobtains position

from GPS, paintsmap from localdatabase.

lat: 40 13 lon: 32 19

I-78

ScotchRoad


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GPS moving map needs

Functionality: For automotive use. Showmajor roads and landmarks.

User interface: At least 400 x 600 pixelscreen. Three buttons max. Pop-up menu.

Performance: Map should scroll smoothly.

No more than 1 sec power-up. Lock ontoGPS within 15 seconds.

Cost: $500 street price = approx. $100

cost of goods sold.

GPS i d


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GPS moving map needs,

contd.

Physical size/weight: Should fit in hand.

Power consumption: Should run for 8

hours on four AA batteries.

GPS i


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GPS moving map

requirements form

name GPS moving map

purpose consumer-grademoving map for driving

inputs power button, twocontrol buttons

outputs back-lit LCD 400 X 600functions 5-receiver GPS; three

resolutions; displayscurrent lat/lon

performance updates screen within0.25 sec of movement

manufacturing cost $100 cost-of-goods-sold

power 100 mW

physical size/weight no more than 2: X 6:,12 oz.


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Specification

A more precise description of the system:

should not imply a particular architecture;

provides input to the architecture designprocess.

May include functional and non-functional

elements.May be executable or may be in

mathematical form for proofs.


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GPS specification

Should include:

What is received from GPS;

map data;user interface;

operations required to satisfy user requests;

background operations needed to keep thesystem running.


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Architecture design

What major components go satisfying thespecification?

Hardware components:CPUs, peripherals, etc.

Software components:

major programs and their operations.

Must take into account functional andnon-functional specifications.

GPS i bl k


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GPS moving map block

diagram

GPS

receiver

search

engine renderer

user

interfacedatabase

display

GPS i h d


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GPS moving map hardware

architecture

GPS

receiver

CPU

panel I/O

display frame

buffer

memory

GPS i ft


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GPS moving map software

architecture

position database

search renderer

timer

user

interface

pixels

D i i h d d


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Designing hardware and

software components

Must spend time architecting the systembefore you start coding.

Some components are ready-made, somecan be modified from existing designs,others must be designed from scratch.


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System integration

Put together the components.

Many bugs appear only at this stage.

Have a plan for integrating components touncover bugs quickly, test as muchfunctionality as early as possible.


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Introduction to

Embedded Systems Dr Pedro Mejia Alvarez

Summary

Embedded computers are all around us.

Many systems have complex embedded hardware and software.

Embedded systems pose many design challenges: design time,deadlines, power, etc.

Design methodologies help us manage the design process.

References:

Overheads forComputers as Components, W.Wolf.Morgan

Kaufman.

Embedded Systems in the Real World, Phillip Koopman. CarnegieMellon University.

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Sistem Embedded (Introduction)

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