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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 toEmbedded Systems Dr. Pedro Mejia Alvarez
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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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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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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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.