UNIT 1.pptx

UNIT I
INTRODUCTION TO EMBEDDED SYSTEM DESIGN
Complex systems and microprocessors– Embedded system
design process–Design example: Model train controller-
Design methodologies- Design flows - Requirement Analysis
– Specifications-System analysis and architecture design –
Quality Assurance techniques - Designing with computing
platforms – consumer electronics architecture – platform-
level performance analysis.

Introduction-Embedded Systems
⚫An Embedded system is an electronic system that has a
software and is embedded in computer hardware.
⚫It is a system which has collection of components used to
execute a task according to a program or commands given
to it.
⚫Examples Microwaveovens, Washing machine,
Telephoneanswering machine system, Elevator controller
system, Printers, Automobiles, Cameras, etc.

Components of Embedded system
⚫Microprocessor
⚫Memory Unit(RAM,ROM)
⚫Input unit(Keyboard,mouse,scanner)
⚫Output unit(pinters,video monitor)
⚫Networking unit(Ethernet card)
⚫I/O units(modem)

Real Time Operating System-RTOS
⚫Real-Time Operating System (RTOS) is an operating
system (OS) intended to serve real-timeapplications
that process data as it comes in, typically without buffer
delays.
⚫It schedules their working and execution by following a
plan to control the latenciesand to meet the dead lines.
⚫Modeling and evaluation of a real-time scheduling
system concern is on the analysis of the algorithm
capability to meet a process deadline.
⚫A deadline is defined as the time required fora task to be
processed.

Classification of Embedded system
1. Small scale Embedded system(8/16bit
microcontroller)
2. Medium Scale Embedded system (16/32bit
microcontroller, more tools like simulator, debugger)
3. Sophisticated Embedded system (configurable
processor and PAL)
Embedded designer-skills
⚫ Designer has a knowledge in the followings field,
⚫ Microcontrollers, Data comm., motors, sensors,
measurements ,C programming, RTOS programming.

COMPLEX SYSTEMS AND MICROPROCESSORS
Embedded(+)computersystem
⚫ Embedded system is a complex system
⚫ It is any device that includes a programmable
computer but is not itself intended to be a
general-purpose computer.

History of Embedded computer system
⚫Computers have been embedded into applications since
the earliest days of computing.
⚫In 1940s and 1950sWhirlwind, designed a first computer to
support real-time operation for controlling an aircraft
simulator.
⚫In 1970s The first microprocessor( Intel 4004) was designed
for an embedded application (Calculator), provided basic
arithmetic functions.
⚫In 1972s The first handheld calculator (HP-35 ) was to
perform transcendental functions , so it used several
chips to implement the CPU, rather than a single-chip
microprocessor.
⚫Designer faced critical problems to design a digital
circuits to perform operations like trigonometric
functions using calculator.
⚫But ,Automobile designers started making use of the
microprocessor for to control the engine by determining
when spark plugs fire, controlling the fuel/air mixture

Levels of Microprocessor
1. 8-bit microcontroller used for low-cost applications and
includes on-board memory and I/O devices.
2. 16-bit microcontroller used for more sophisticated
applications that may require either longer word lengths or
off-chip I/O and memory.
3. 32-bit RISC microprocessor offers very high
performance for computation-intensive
applications.

Microprocessor Uses/Applications
⚫Microwaveoven has at least one microprocessor to
control oven operation
⚫Thermostat systems, which change the temperature
level at various times during the day
⚫The modern camera is a prime exampleof the
powerful features that can be added under
microprocessorcontrol.
⚫Digital television makes extensive use of embedded
processors.

Embedded Computing Applications
⚫ExBMW 850i Brake and Stability Control System
⚫The BMW 850i was introduced with a sophisticated
system for controlling the wheels of the car.
⚫Which uses An antilock brake system (ABS) and An
automatic stability control (ASC +T) system.

1. An antilock brake system (ABS)
⚫Reduces skidding by pumping the brakes.
⚫It is used to temporarily release the brake on a wheel when
it rotates too slowly—when a wheel stops turning, the car
starts skidding and becomes hard to control.
⚫It sits between the hydraulic pump, which provides
power to the brakes.
⚫It uses sensors on each wheel to measure the speed of the
wheel.
⚫The wheel speeds are used by the ABS system to determine
how to vary the hydraulic fluid pressure to prevent the
wheels from skidding.

2. An automaticstabilitycontrol (ASC +T) system
⚫It is used to control the engine powerand the brake to improve
the car’s stabilityduring maneuvers.
⚫Itcontrols fourdifferent systems: throttle, ignition timing,
differential brake, and (on automatic transmission cars) gear
shifting.
⚫Itcan be turned off by the driver, which can be
importantwhen operating with tire snow chains.
⚫It has control unit has two microprocessors , one of which
concentrates on logic-relevant components and the other on
performance-specific components.
⚫The ABS and ASC+ T must clearly communicate because
the ASC+ T interactswith the brake system.

1. Complex algorithms-The microprocessor that controls an
automobile engine must perform complicated filtering
functions to optimize the performance of the car while
minimizing pollution and fuel utilization.
2. User interface-The moving maps in Global
Positioning System (GPS) navigation are good
examples of user interfaces.
3. Real time-Embedded computing systems have to perform in
real time—if the data is not ready by a certain deadline,the
system breaks. In some cases, failure to meet a deadline or
missing a deadline does not create safety problems but does
create unhappy customers
Characteristics of Embedded computing
Applications

4. Multirate-Multimedia applications are examples of
multirate behavior.
The audio and video portions of a multimedia stream run
at very different rates, but they must remain closely
synchronized. Failure to meet a deadline on either the
audio or video portions spoils the perception of the entire
presentation.
5. Manufacturing cost- It is depends on the type of
microprocessor used, the amount of memory required, and
the types of I/O devices.
6. Power and energy-Power consumption directly affects
the cost of the hardware, since a larger power supply may
be necessary.
7. Energy consumption affects battery life, which is
important in many applications, as well as heat
consumption, which can be important even in desktop
applications.

Why Use Microprocessors?
⚫Microprocessors are a very efficient way to implement digital
systems.
⚫It make it easier to design families of products with various
featureat differentprice points
⚫Itcan be extended to provide new features to keep up with
rapidly changing markets.
⚫It executes program very efficiently
⚫It make their CPU run very fast
⚫Implementing several function on a single processor

Why not use PCs for all embedded
computing?
⚫Real time performance is very less in PC because
of differentarchitecture.
⚫It increases the complexity and price of components
due to broad mix of computing requirements.

Challenges in Embedded Computing System Design
1. How much hardware do we need?
⚫To meet performance deadlines and manufacturing cost constraints, the
choice of Hardware is important.
⚫Too much hardwareand it becomes too expensive.
2. How do we meet deadlines?
⚫Tospeed up the hardware so that the program runs faster. But the
system more expensive.
⚫ It is also entirely possible that increasing the CPU clock rate may not
make enough difference to execution time, since the program’sspeed
may be limited by the memory system.
3. How do we minimize power consumption?
⚫In battery-powered applications, powerconsumption is extremely
important.
⚫In non-battery applications, excessive powerconsumption can
increase heat dissipation.
⚫Careful design is required to slow down the noncritical parts of the
machine for powerconsumption while still meeting necessary
performance goals.

4) How do we design for upgradability?
⚫The hardware platform may be used over several product
generations,or for several different versions ,able to add features by
changing software.
4.1) Complex testing: Run a real machine in order to generate the proper
data.
⚫Testing of an embedded computer from the machine in which it is
embedded.
2)Limited observability and controllabilityNo keyboard and screens, in
real- time applications we may not be able to easily stop the system to
see what is going on inside and to affect the system’s operation.
3) Restricted development environments:
⚫We generally compile code on one type of machine, such as a PC,
and download it onto the embedded system.
⚫To debug the code, we must usually rely on programs that run on the
PC or workstation and then look inside the embedded system.

Performance in Embedded Computing
⚫Embedded system designers have to set theirgoal —their program must
meet its deadline.
Performance Analysis
1. CPU: The CPU clearly influences the behavior of the program,
particularly when the CPU is a pipelined processorwith a cache.
2. Platform: The platform includes the bus and I/O devices. The
platform components that surround the CPU are responsible for
feeding the CPU and can dramatically affect its performance.
3. Program: Programs are very large and the CPU sees only a small
window of the program at a time. We must consider the structure
of the entire program to determine its overall behavior.
4. Task: We generally run several programs simultaneously on a CPU,
creating a multitasking system. The tasks interact with each other in
ways that have profound implications for performance.
5. Multiprocessor: Many embedded systems have more than one
processor—they may include multiple programmable CPUs as well
as accelerators. Once again, the interaction between these processors
adds yet more complexity to the analysis of overall system
performance.

2)EMBEDDED SYSTEM DESIGN PROCESS
Design process has two objectives as follows.
1. Itwill give us an introduction to the various steps
in embedded system design.
2. Design methodology
I. Design to ensure that we havedone everything we
need to do, such as optimizing performance or
performing functional tests.
II. Itallows us to develop computer-aided design
tools.
III.A design methodology makes it much easier for
members of a design team to communicate.

Levels of abstraction in the design process.
1)Requirements
•Itcan beclassified in to functional or nonfunctional
1.1)Functional Requirements
•Gatheran informal description from the customers.
•Refine the requirements into a specification that contains
enough information to design the system architecture.
•Ex:Sample Requirements form
•NameGiving a name to the project
PurposeBrief one- or two-line description of what the system
is supposed to do.
•Inputs& Outputs Analog electronicsignals? Digital data?
Mechanical inputs?
•Functions detailed description of what the system does
Performance computations must be performed within a
certain time frame
•Manufacturing cost cost of the hardwarecomponents.
Power how much powerthe system can consume
Physical size and weight indication of the physical size
of the system

1.2) Non-Functional Requirements
⚫Performance depends upon approximate time to perform a user-
level function and also operation must be completed within deadline.
⚫CostManufacturing cost includes the cost of components and
assembly. Nonrecurring engineering (NRE) costs include the
personnel and other costs of designing the system
⚫Physical Size and WeightThe final system can vary depending upon
the application.
⚫Power ConsumptionPower can be specified in the requirements stage
in terms of battery life.

2)SPECIFICATION
⚫The specification must be carefully written so that it accurately
reflects the customer’s requirements.
⚫It can be clearly followed during design.
3) Architecture Design
⚫The architecture is a plan for the overall structure of the system.
⚫It is in the form block diagram that shows a majoroperation and data
flow.
4) Designing Hardware and Software Components
⚫The architectural description tells us what components we need
include both hardware—FPGAs, boards & software modules
5)System Integration
⚫Only after the components are built, putting them togetherand
seeing a working system.
⚫Bugs are found during system integration, and good planning can help
us find the bugs quickly.

Embedded system Design Example
⚫GPS moving map

Design Process Steps
1. Requirements analysis of a GPS moving map
⚫ The moving map is a handheld device that displays for the usera map of the
terrain around the user’s current position.
⚫ The mapdisplay changes as the userand the mapdevice change position.
⚫ The moving map obtains its position from the GPS, a satellite-based navigation
system.
Name GPS moving map
Purpose Consumer-grade moving map fordriving use
Inputs Power button, twocontrol buttons
Outputs Back-litLCD display 400 600
Functions Uses 5-receiverGPS system; threeuser-selectable
resolutions;alwaysdisplayscurrent latitude
and longitude
Performance Updatesscreenwithin 0.25 seconds upon movement
Manufacturingcost $30
Power 100mW
Physical sizeand
weight
Nomore than 2”X 6, ” 12 ounces

Design Process Steps
2) FunctionalityThis system is designed for highwaydriving and similar uses.
Thesystem should show major roads and other landmarks available in standard
topographic databases.
3) User interfaceThe screen should haveat least 400X600 pixel resolution. The device should
becontrolled by no more than 3 buttons.
A menu system should pop up on the screen when buttons are pressed to
allow the user to make selections to control the system.
4)Performance The map should scroll smoothly.
Upon power-up, a display should take no more than 1sec to appear.
Thesystem should beable to verify its position and display the current map
within 15 s.
5)Cost Theselling cost of the unit should be no more than $100.
6) Physical size and weightThe device should fit comfortably in the palm of the hand.
7) Powerconsumption Thedevice run forat least 8 hrs on 4 AA batteries.

8) specification
1. Data received from the GPS satellite constellation.
2. Mapdata.
3. User interface.
4. Operations that must be performed to satisfy customerrequests.
5. Background actionsrequired to keepthe system running, suchas
operating the GPS receiver.

Hardware architecture
•onecentral CPU surrounded
by memoryand I/O devices.
•It used two memories: a frame
buffer for the pixels to be
displayed and a separate
program/data memory for general
use by the CPU.
Software architecture
•Timer to control whenwe read the
buttons on the user interfaceand
renderdataonto thescreen.
•Units in the software block diagram
will be executed in the hardware block
diagram and whenoperationswill be
performed in time.

3)FORMALISM FOR SYSTEM DESIGN
⚫ UML(Unified Modeling Language) is an object-oriented modeling
languageused to capture all thesedesign tasks.
⚫ It encourages the design to bedescribed asa numberof interacting
objects, ratherthan blocksof code.
⚫ objectswill correspond to real piecesof software or hardware in the
system.
⚫ It allowsa system to bedescribed in away thatclosely models real-
world objectsand their interactions.
Classification of
descriptor
3.1)Structural
Description
3.2)Behavioral
Description

1) Structural Description
⚫ Itgives basiccomponents of the system and designers can learn how to
describe these components in terms of object.
3.1.1) OBJECT in UML NOTATION
⚫ An object includes a set of attributes that define its internal state.
⚫ An objectdescribing a display (CRT screen) is shown in UML notation in
Figure.
⚫ Theobject has a unique name, and a memberof a class.
⚫ The name is underlined to show that this is adescription of an objectand not
of a class.
⚫ The text in the folded-corner page icon is a note.
An object in UML notation

3.1.2)CLASS IN UML NOTATION
⚫ All objects derived from the same
class have the same characteristics,
but attributes may have different
values.
⚫ It also defines the operations that
determine how the object interacts
with the restof the world.
⚫ It defines both the interface for a
particular type of object and that
object’s implementation.

Relationships between objects and classes
1. Association occurs between objects that communicate with each other but
have no ownership relationship between them.
2. Aggregation describes a complex object made of smallerobjects.
3. Composition It is a type of aggregation in which the owner does not allow
access to the component objects.
4. Generalization allows us todefine one class in terms of another.

Derived classes as a form of generalization in UML
•A derived class is defined to include all the
attributes of its baseclass.
•Display is the base class and BW display and
color map display are the two derived classes.
•BW display represents black and whitedisplay.

Multiple inheritance in UML
•UML allows to define multiple inheritance, in which a class is derived from more
than one baseclass.
•Multimedia display class bycombining the Display class with a Speakerclass for
sound.
•Thederived class inherits all the attributes and operations of both its baseclasses,
Display and Speaker.
•

Links and Association
⚫ A link describesa relationship between objectsand association is to
link asclass is toobject.
⚫ Links used to make to stand associations capture type information
aboutthese links.
⚫ Theassociation isdrawn asa line between the two labeled with the
nameof theassociation, namely, contains.

⚫ Behaviorof an operation is specified bya state machine.
⚫ Thesestate machineswill not relyon theoperation of aclock.
⚫ Changes from onestate toanotherare triggered by theoccurrenceof
events.
⚫ Theevent maygenerated from theoutsideor insideof the system.
3.2)Behavioral Description

Signal, call, and time-out events in UML.

⚫ Signal isan asynchronousoccurrence.
⚫ It is defined in UML byan object that is labeled asa <<signal>>.
⚫ Signal may haveparameters thatare passed to the signal’s receiver.
⚫ Call event follows the model of a procedurecall in a programming
language.
⚫ Time-outevent causes the machine to leavea state afteracertain
amountof time.
⚫ The label tm(time-value) on theedgegives theamountof timeafter
which the transitionoccurs.
⚫ It is implemented with an external timer.

State Machine specification in UML
⚫ Thestart and stop states arespecial states which organize the f low of the state
machine.
⚫ Thestates in the state machine representdifferent operations.
⚫ Conditional transitions out of states based on inputs or results of some
computation.
⚫ An unconditional transition to the next state.

Sequence diagram in UML
⚫ Sequence diagram is similar toa hardware timing diagram, although the time
flowsvertically in a sequence diagram, whereas time typically flows horizontally
in a timing diagram.
⚫ It is designed to show particularchoice of events—it is not convenient for
showing a number of mutuallyexclusive possibilities.

4) Design:Model Train Controller
⚫ In order to learn how to use UML to model systems specify a simple system
(Ex: model train controller)
⚫ The usersends messages to the train with a control boxattached to the tracks.
⚫ Thecontrol box may havecontrols such as a throttle, emergency stop button,
and so on.
⚫ The train Rx its electrical power from the two rails of the track.
CONSOLE
⚫ Each packet includes an address so that the console can control several trains
on the same track.
⚫ The packet also includes an errorcorrection code (ECC) to guard against
transmission errors.
⚫ This is aone-way communication system—the model train cannot send
commands back to the user.

REQUIREMENTS
⚫ Theconsole shall beable to control up toeighttrains on asingle track.
⚫ The speed of each train controllable bya throttle toat least 63 different
levels in each direction (forward and reverse).
⚫ Thereshall bean inertiacontrol toadjustthe speed of train.
⚫ Thereshall bean emergencystop button.
⚫ An errordetectionschemewill be used to transmit messages.

Requirements:Chart Format
⚫ Name
⚫ Purpose
⚫ Inputs
Model train controller
Control speed of up to eight model trains
Throttle, inertia setting, emergency stop, train
number
Train control signals
Set engine speed based upon inertia settings;
⚫ Outputs
⚫ Functions
respond
⚫ Performance
⚫ Manufacturing cost
⚫ Power
⚫ Physical size and weight
weight
Can update train speed at least 10 times persecond
$50
10W
Console should be comfortable for two
hands,approximatesize of standard
keyboard;
2 pounds

Digital Command Control (DCC)
⚫ Standard S-9.1 how bits are encoded on the rails for transmission.
⚫ Standard S-9.2 defines the packets that carry information.
⚫ Thesignal encoding system should not interfere with power transmission
⚫ Datasignal should not change the DC value of the rails.
⚫ Bits areencoded in the time between transitions.
⚫ Bit 0 is at least 100 s while bit 1 is nominally 58 s.

Packet Formation in DCC
⚫ The basic packet format is given by
⚫ P  preamble, which is a sequence of at least 10 1 bits.
⚫ S  packet start bit. It is a 0 bit.
⚫ A address is 8 bits long. Theaddresses 00000000, 11111110, and 11111111 are
reserved.
⚫ s data byte start bit, which, like the packet start bit, is a 0.
⚫ D data byte includes 8 bits. A data byte may contain an address, instruction,
data, orerrorcorrection information.
⚫ E packet end bit, which is a 1 bit.

Baselinepacket
⚫ The minimum packet that must be accepted byall DCC implementations.
⚫ It has three data bytes.
⚫ Address data byte gives the intended receiverof the packet
⚫ Instruction data byte provides a basic instruction
⚫ Errorcorrection data byte is used to detect and correct transmission errors.
Date byte
⚫ Bits 0–3 provide a 4-bit speed value.
⚫ Bit 4 has an additional speed bit.
⚫ Bit 5 gives direction, with 1 for forward and 0 for reverse.
⚫ Bits 6-7 areset at 01  provides speed and direction.

Conceptual Specification
⚫ Conceptual specification allows us to understand the system a little better.
⚫ A train control system turns commands into packets.
⚫ A command comes from the command unit whilea packet is transmitted over the
rails.
⚫ Commands and packets may not be generated in a 1-to-1 ratio

UML collaboration diagram for train
controller system
⚫ Thecommand unit and receiverareeach represented byobjects.
⚫ Thecommand unit sends a sequence of packets to the train’s receiver, as
illustrated by the arrow messages as 1..n.
⚫ Those messages areof course carried over the track.

UML class diagram for the train controller

Basic characteristics of UML classes
⚫ Console class describes the command unit’s front panel, which contains
the analog knobs and hardware to interface to the digital parts of the system.
⚫ Formatter class includes behaviors that know how to read the panel knobs and creates a
bit stream for the required message.
⚫ Transmitter class interfaces to analog electronics to send the message along the track
⚫ Knobs* describes the actual analog knobs, buttons, and levers on the control panel.
⚫ Sender* describes the analog electronics that send bits along the track.
⚫ Receiver class knows how to turn the analog signals on the track into digital form.
⚫ Controller class includes behaviors that interpret the commands and figures out how to
control the motor.
⚫ Motor interface class defines how to generate the analog signals required to control the
motor.
⚫ Detector* detects analog signals on the track and converts them into digital form.
⚫ Pulser* turns digital commands into the analog signals required to control the motor
speed.

Detailed Specification
•The Panel has three knobs
•train number (which train is currently
being controlled).
•speed (which can be positive or negative),
and inertia.
•It also has one button for emergency-
stop.
•When we change the train number
setting, to reset the other controls to the
proper values for that train.
•so that the previous train’s control
settings are not used to change the current
train’s settings.

Class diagram for panel
•The Panel class defines a behavior foreach of the controls on the panel.
• The new-settings behavior uses the set-knobs behavior of the Knobs*
•Change the knobs settings whenever the train number setting is changed.
•The Motor-interface defines an attribute for speed that can be set by other
classes.
.

Class diagram for the Transmitter and Receiver
•Theyprovide the software interface to the physical devices that
send and receive bits along the track.
•TheTransmitter provides a behavior message that can be sent
•The Receiverclass provides a read-cmd behavior to read a messageoff
the tracks.

Class diagram for Formatter
⚫ The formatter holds the current control settings forall of the trains.
⚫ The send-command serves as the interface to the transmitter.
⚫ The operate function performs the basicactions for the object.
⚫ The panel-active behavior returns true whenever the panel’s values do not
correspond to the currentvalues

Class diagram for Controller
•The Controller’s operate behavior must execute several behaviors to
determine the nature of the message.
•Once the speed command has been parsed, it must send a sequence of
commands to the motor to smoothly change the train’s speed.

Sequences diagram for transmitting a
control input
⚫ Sequence diagram
specify the interface
between more than one
classes.
⚫ Its detailed operations
and whatways its going
tooperate

1.4DESIGN METHODOLOGIES
⚫ Design of Embedded system is not an easy task.
⚫ The main goal of a design process is to create a product that does something useful.
⚫ Typical specifications for a product are functionality , manufacturing cost, performance and
powerconsumption.
Design process has several important goals as follows
Time-to-market
⚫ Customers always want new features.
⚫ The product that comes out first can win the market, even setting customer preferences for
future generations of the product.
Design cost
⚫ Consumer products are very cost sensitive, and it is distinct from manufacturing cost.
⚫ Design costs can dominate manufacturing costs.
⚫ Design costs can also be important for high-volume consumer devices when time-to-market
pressures cause teams to swell in size.
Quality
⚫ Customers want their products fast and cheap.
⚫ Correctness, reliability, and usability must be explicitly addressed from the beginning of the
design job to obtain a high-quality product at the end

1.5Design flows
⚫ A design flow is a sequence of steps to be followed during a design.
⚫Some of the steps can be performed by tools and other steps can be performed by hand.
Types of Software development models
1. Waterfall model
2. Spiral model
3. Successive refinement development model
4. Hierarchical design model

⚫ The waterfall development model consists of five major phases.
⚫ Requirements analysis determines the basic characteristics of the system.
⚫ Architecture designIt decomposes the functionality into major components
⚫ CodingIt implements the pieces and integrates them.
⚫ TestingIt detemines bugs.
⚫ Maintenance It entails deployment in the field, bug fixes,and upgrades.
⚫ The waterfall model makes work flow information from higher levels of abstraction to
more detailed design steps.
1.5.1)Waterfall model

1.5.2)Spiral model
⚫ The spiral model assumes that several versions of the
system will be built.
⚫ Each level of design, the designers go through
requirements,construction,and testing phases.
⚫ At later stages when more complete versions of the
system are constructed.
⚫ Each phase requires more work, widening the design
spiral.
⚫ The first cycles at the top of the spiral are very small
and short.
⚫ The final cycles at the spiral’s bottom add detail
learned from the earlier cycles of the spiral.
⚫ The spiral model is more realistic than the waterfall
model because multiple iterations needed to
complete a design.
⚫ But too many spirals may take long time required for
design.

1.5.3)Successive refinement design model
⚫ In this approach, the system is built several times.
⚫ A first system is used as a rough prototype.
⚫ Embedded computing systems are involved the design of hardware/software project.
⚫ Front-end activities are specification and architecture and also includes hardware and
software aspects.
⚫ Back-end activities  includes integration and testing.
⚫ Middle activitiesincludes hardware and software development.

1.5.4)Hierarchical design flow
⚫ Many complex embedded systems are built of smallerdesigns.
⚫ Thecomplete system may require the design of significant software
components.
⚫ It has many levels of abstraction to design flows for individual components.
⚫ The implementation phase contains a complete flow from specification
through testing.
⚫ Each flow will probably be handled by separate peopleor teams.
⚫ The teams must relyon each other’s results.
⚫ Thecomponent teams take their requirements from team handling the next
higher level of abstraction.
⚫ The higher-level team relieson the quality of design and testing performed by
the component team.

5) Concurrent engineering
⚫ Reduced design time is an important goal for concurrent engineering.
⚫ It eliminate “over-the-wall” design steps, one designer performs an isolated task and then
throws the result to the next designer.
Concurrent engineering efforts are comprised of several elements.
⚫ Cross-functional teams include members from various disciplines ( manufacturing,
hardware and software design, marketing)
⚫ Concurrent product realize the process activities .
⚫ Designing various subsystems simultaneously, is reducing design time.
⚫ Integrated project managementensures that someone is responsible for the entire project.
⚫ Early and continual supplier make the best use of suppliers’ capabilities.
⚫ Early and continual customer ensure that the product meets customers’ needs.

Concurrent Engineering Applied to Telephone Systems

1. Benchmarking They compared themselves to competitors and found that it took
them 30% longer to introduce a new product than their best competitors.
2. Breakthrough improvement.
⚫ Increased partnership between design and manufacturing.
⚫ Continued existence of the basic organization of design labs and manufacturing.
⚫ Support of managers at least two levels above the working level.
3. Characterization of the current process.
⚫ Too many design and manufacturing tasks were performed sequentially.
4. Create the target process The core team created a model for the new development
process.
5. Verify the new process test the new process.
6. Implement across the product lineThis activity required training of personnel,
documentation of the new standards and procedures, and improvements to information
systems.
7. Measure results and improvePerformance of the new design was measured.

6. REQUIREMENTS ANALYSIS
⚫ RequirementsIt is a informal descriptions of what the customerwants.
⚫ A functional requirement states what the system mustdo.
⚫ A nonfunctional requirementIt can be physical size, cost, powerconsumption,
design time, reliability, and soon.
Requirementsof tests
⚫ CorrectnessRequirements should not mistakenly describewhat the customer
wants.
⚫ UnambiguousnessRequirements document should be clearand haveonly one
plain language interpretation.
⚫ Completeness Requirements all should be included.
⚫ Verifiability cost-effective way to ensure thateach requirement is satisfied in the
final product.
⚫ ConsistencyOne requirement should not contradict anotherrequirement.
⚫ ModifiabilityThe requirements document should be structured so that it can
be modified to meetchanging requirements without losing consistency.
⚫ TraceabilityAble to trace forward /backward from the requirements.

7) SPECIFICATIONS
⚫ SpecificationsIt is a
detailed descriptions of the
system that can be used to
create thearchitecture.
Control-oriented specification
languages
⚫ SDL specifications include
states, actions, and both
conditional and
unconditional transitions
between states.
⚫ SDL is an event-
oriented state machine
model.
⚫ Statechart has some
important concepts.
⚫ Statecharts allow states to
be grouped togetherto
show common
functionality.

⚫ Basicgroupings(OR)
⚫ State machinespecifies that the machinegoes to state s4 from any of
s1, s2, ors3 when they receivethe input i2.
⚫ The State chartdenotes this commonality by drawing an OR state
around s1, s2, and s3 .
⚫ Single transition outof the OR state s123 specifies that the machine
goes to s4 when it receivesthe i2 input while in any state included in
s123.
⚫ Multiple ways to get into s123 (via s1 or s2), and transitions between
states within the OR state (from s1 to s3 ors2 to s3).
⚫ The OR state is simply a tool for specifying someof the transitions
relating to these states.

⚫ Basicgroupings(AND)
⚫ In the State chart, the AND state sab is decomposed into two components, sa and sb.
⚫ When the machine enters the AND state, it simultaneously inhabits the state s1 of
component sa and the state s3 of component sb.
⚫ When it enters sab, the complete state of the machine requires examining both sa and sb.
⚫ State s1-3 in the State chart machine having its sa component in s1 and its sb component in
s3.
⚫ When exit from cluster states go to s5 only when in the traditional specification, we are in
state s2-4 and receive input r.

1) Advanced specifications
⚫It ensure the correctness and safety of this system.
Ex Traffic Alert and Collision Avoidance System(TCAS)
⚫ It is a collision avoidance system for aircraft.
⚫ TCAS unit in an aircraft keeps track of the position of other nearby aircraft.
⚫ It uses pre-recorded voice (“DESCEND!) commands for mid-air collision.
⚫ TCAS makes sophisticated decisions in real time and is clearly safety critical.
⚫ It must detect as many potential collision events as possible .
⚫It must generate a few false alarms ,at extreme maneuvers in potentially dangerous.
TCAS-II specification(RSML Language) Transition states

Collision Avoidancesystem
⚫ The system has Power-off and Power-on states .
⚫ In the power on state, the system may be in Standby or Fully operational mode.
⚫ In the Fully operational mode, three components are operating in parallel, as specified
by the AND state.
⚫ The own aircraft subsystem to keep track of up to 30 other aircraft.
⚫ Subsystem to keep track of up to 15 Mode S ground stations, which provide radar
information.

8. SYSTEM ANALYSIS AND ARCHITECTURE DESIGN
⚫ The CRC card methodology analyze and understanding the overall structure of a complex
system.
CRC cards
⚫ Classes define the logical groupings of data and functionality.
⚫ Responsibilities describe what the classes do.
⚫ Collaborators are the other classes with which a given class works.
⚫ It has space to write down the class name, its responsibilities and collaborators, and other
information.
Layoutof CRC card

⚫ A class may represent a real-world objectof the system.
⚫ A class has both an internal state and a functional interface.
⚫ The functional interface describes the class’scapabilities.
⚫ The responsibility set is describing that functional interface.
⚫ Thecollaborators of a classare simply the classes that it talks or calls
upon to help it do its work.
⚫ CRC card Analysis Process
1. Developan initial listof classesWrite down theclass name and
functions of it.
2. Writean initial list of responsibilities and collaborators.
3. Createsome usagescenariosdescribewhat the system does.
4. Walk through the scenariosEach person on the team represents one or
more classes.
5. Refine the classes, responsibilities, and collaborators make changes to
the CRC cards.
6. Add class relationships subclassand super-classcan beadded to the
cards.

Ex:Elevator system
1. One passenger requests a caron a floor, gets in the carwhen it arrives, requests
another floor, and gets out when the carreaches that floor.
2. One passenger requests a caron a floor, gets in the carwhen it arrives, and
requests the f loor that the car is currently on.
3. A second passenger requests a carwhile another passenger is riding in the
elevator.
4. Two people push f loor buttons on different f loors at the same time.
5. Twopeople push carcontrol buttons in different cars at the same time.

1.9) Quality Assurance techniques(QA)
⚫The quality assurance (QA) process is vital for the delivery of a
satisfactory system.
⚫International Standards Organization (ISO) has created a set of quality
standards known as ISO 9000.
⚫Itwas created to apply to a broad range of industries, including
limited to embedded hardware and software.
ISO 9000 quality management parameters
⚫Process is crucialKnowing what steps are to be followed to create a
high-quality product.
⚫Documentation is importanthelps internal quality monitoring groups
to ensure that the required processes and helps outside groups
understand the processes and how they are being implemented.
⚫Communication is important people should understand not only
their specific tasks but also how their jobs can affect overall system
quality.

Capability Maturity Model (CMM)
⚫It is used to measuring the quality of an organization’s
software development.
1. InitialA poorly organized process, with very few well-
defined processes. Success of a projectdepends on the
efforts of individuals, not the organization itself.
2. Repeatable provides basic tracking mechanisms to
understand cost, scheduling .
3. DefinedThe management and engineering processes
are documented and standardized.
4. Manageddetailed measurements of the development
process and product quality.
5. Optimizingfeedback from detailed measurements is
used to continually improve the organization’s
processes.

⚫Verifying the specificationDiscovering bugs early is crucial
because it prevents bugs from being released to customers,
minimizes design costs, and reduces design time.
⚫Validation of specificationscreating the requirements,
including correctness, completeness, consistency, and so on
Design reviews
⚫ The review leader coordinates the pre-meeting activities, the
design review itself, and the post-meeting follow-up.
⚫The reviewer records the minutes of the meeting so that
designers and others know which problems need to be fixed.
⚫The review audience studies the component.

1.10 DESIGNING WITH COMPUTING PLATFORM
1.10.1 System Architecture
⚫The architecture of an embedded computing system
includes both hardware and software elements
HARDWARE
⚫CPU Thechoice of the CPU is one of the most
important, but it can be considered the software that
will execute on the machine.
⚫Bus The choice of a bus is closely tied to that of a
CPU,bus can handle the traffic.
⚫MemorySelection depends total size and speed of the
memory will play a large part in determining system
performance.
⚫Inputand outputdevices Dependig upon the system
requirements

SOFTWARE
Run Timecomponents
⚫ It isacritical partof the platform.
⚫ An operating system is required tocontrol CPU and its multiple
processes .
⚫ A file system is used in manyembedded systems toorganize internal
dataand interface with othersystems
Supportcomponents
⚫ It is acomplex hardwareplatform.
⚫ Withoutpropercodedevelopmentand operating system, the hardware
itself is useless.

⚫ CPU provides basiccomputational facilities.
⚫ RAM is used forprogramstorage.
⚫ ROMholds the bootprogram.
⚫ DMAcontrollerprovides DMA capabilities.
⚫ Timers used by theoperating system foravarietyof purposes.
⚫ High-speed busconnected to the CPU bus througha bridge, allows
fastdevicestocommunicatewith the restof thesystem.
⚫ low-speed bus provides an inexpensive way toconnectsimpler
devices.

1.10.3 Development Environments
⚫ Development process  used to makea complete design
of the system.
⚫ Itguides thedevelopers how to design a system .
⚫ An embedded computing system has CPU ,memory, I/O
devices.
⚫ Development of embedded system have both hardware&
software.
⚫Thesoftware development on a PC orworkstation known
asa host.
•The host and target are frequentlyconnected bya USB link.
•The target must include a small amount of software to talk to the host
system.

Functions of Host system
⚫ Load programs into the target
⚫ Start and stop program execution on the target
⚫Examine memory and CPU registers. Cross-
Compiler
⚫ Compiler kind of software that translate one form of pgm to another form of pgm.
⚫ Cross Compileris a compiler that runs on one type of machine but generates
code foranother
⚫ Aftercompilation, the executable code is downloaded to the embedded system bya serial
link.
⚫ A PC orworkstation offers a programming environment .
⚫ But one problem with this approach emerges when debugging code talks to I/O devices.
⚫ Testbench program can be built to helpdebug the embedded code.
⚫ It may also take the output values and compare them against expected values.

1.10.4Debugging Techniques
⚫ It is the process of checking errors and correcting those errors.
⚫ It can bedone by compiling and executing the code on a PC orworkstation.
⚫Itcan be performed by both H/W and S/W sides.
Softwaredebugging tools
1. Serial Port tool
⚫ Itwill perform the debugging process from the initial state of embedded system
design.
⚫ It can be used not only for development debugging but also for diagnosing
problems in the field.
2. Breakpoints tool
⚫ used to specify an address at which the program’sexecution is to break.
⚫ When the PC reaches that address, control is returned to the monitor program.
⚫ From the monitor program, the usercan examine and/or modify CPU registers,
afterwhich execution can be continued.

Breakpoint is a location in memory atwhich a program stops executing and
returns to the debugging tool or monitor program.
Toestablish a breakpointat location 0x40c in some ARM code, replaced the branch
(B) instruction with a subroutine call (BL) to the breakpoint handling routine

Hardwaredebugging tools
⚫ Hardwarecan bedeployed to givea clearerview on what is happening when the
system is running.
1. Microprocessor In-Circuit Emulator (ICE)
⚫ It is a specialized hardware tool that can help debug software in a working
embedded system.
⚫ In-circuit emulator is a special version of the microprocessor that allows its
internal registers to be read out when it is stopped
2. Logic Analyer
⚫ Theanalyzer can sample many different signals simultaneously but can display
only 0, 1, orchanging values foreach.
⚫ The logicanalyzer records thevalues on the signals into an internal memory
and then displays the results on a display once the memory is full.

Architecture of a logic analyzer

Data modes of logic analyzer
State modes
⚫ State mode represent different waysof sampling thevalues.
⚫ It uses the own clock to control sampling
⚫ It samples each signal only one perclock cycle.
⚫It has less memory to storea given numberof system clock.
Timing modes
⚫ Timing mode uses an internal clock that is fast enough to take several samples
perclock period in a typical system.

1.10.5)Debugging Challenges
⚫ Logical errors in software can be hard to track down and itwill create
many problems in real timecode.
⚫ Real-timeprogramsare required to finish theirworkwithin a certain
amountof time.
⚫ Run time pgm run too long, theycancreatevery unexpected behavior.
⚫ Missing of Deadline makesdebugging processasdifficult.

1.11 Consumer Electronic Architecture
⚫ Consumer electronic refers to anydevice containing an electroniccircuit board
that is intended foreveryday use by individuals.
⚫ EgTV,cameras,digital cameras,calculators,DVDs,audio devices,smart phones
etc..,
1.11..1)Functional Requirements
1. Multimedia
⚫ The media may be audio, still images, orvideo.
⚫ These multimedia objects aregenerally stored in compressed form and must be
uncompressed to be played .
⚫ Eg multimedia compression standards (MP3,Dolby Digital(TM))
⚫ audio; JPEG forstill images; MPEG-2, MPEG-4, H.264, etc. forvideo.
2. Data storage and management People want to selectwhat multimedia objects
they save or play, data storage goes hand-in-hand with multimedia capture and
display. Many devices provide PC-compatible file systems so that data can be
shared more easily.
3. Communications Communications may be relatively simple, such as a USB
⚫ and another is Ethernet port ora cellular telephone link.

1.11.2)Non-Functional Requirements
⚫ Manydevices are battery-operated, which means that they must operate under
strictenergy budgets.
⚫ Battery(75mW) support not only the processors but also the display, radio,
etc.
⚫ Consumer electronics must also be very inexpensive but provide very high
performance.

⚫ use case for selecting and playing a multimedia object (audio clip, a picture,etc.).
⚫ Selecting an object makes use of both the user interface and the file system.
⚫ Playing also makes use of the file system as well as the decoding subsystem and
I/O subsystem.
Use case for playing
multimedia

Use case of synchronizing with a host
system
⚫ use case forconnecting toa client.
⚫ Theconnection may beeitherovera local connection like USB orover the
Internet.
⚫ Some operations may be performed locallyon the client device
⚫ most of the work is done on the host system while the connection is
established

1.11.3)Functional architecture of
Consumer Electronics Device(CED)

⚫ It is a two-processorarchitecture.
⚫ If more computation is required, more DSPs and CPUs may be added.
⚫ The RISC-CPU runs the operating system, runs the user interface, maintains
the file system, etc.
⚫ DSP it is a programmable one, which performs signal processing.
⚫ Operating system runs on the CPU must maintain processes and the file
system.
⚫ Depending on the complexity of the device, the operating system may not need
tocreate tasks dynamically.
⚫ If all tasks can be created using initialization code, the operating system can be
made smallerand simpler.

1.11.4 Flash File Systems
⚫ Manyconsumerelectronicsdevicesuse flash memory for mass storage.
⚫ Flash memory is a typeof semiconductor memory ,unlike DRAM or
SRAM, provides permanentstorage.
⚫ Valuesarestored in the flash memorycell aselectricchargeusing a
specialized capacitorthatcan store thecharge foryears.
⚫ The file system of adevice is typically shared with a PC.
⚫ Standard file systemhastwo layers.bottom layerhandles physical
reads and writes on the storage device and the top layer provides a
logical viewof the file system.
⚫ Flash file systemimposesan intermediate layerthatallows the logical-
to-physical mapping of files to bechanged.

1.12 Platform-Level Performance Analysis
⚫ System-Level Performance involves much more than the CPU.
⚫ To movedata from memory to the CPU to process it. Toget the data from
memory to the CPU we must.
1. Read from the memory.
2. Transferover the bus to the cache.
3. Transferfrom thecache to the CPU.

⚫ The performance of the system based on Bandwidth of the system.
⚫ We can increase bandwidth in two ways:
1) By increasing the clock rate of the bus
2) By increasing the amount of data transferred perclock cycle.
Forexample, bus tocarry four bytes or 32 bits per transfer, wewould reduce
the transfer time to 0.058 s. If we also increase the bus clock rate to 2 MHz,
then wewould reduce the transfer time to 0.029 s ,which is within our time
budget for the transfer.
t=TP
tbus cyclecounts
Tbus cycles.
pbus clock period

Parallelism
⚫ Direct memoryaccess isaexampleof parallelism.
⚫ DMA was designed tooff-load memory transfers from the CPU.
⚫ The CPU can dootheruseful work while the DMA transfer is running.

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