EMBEDDED SYSTEMS - MSc Sem III (Final).ppt

• Introduction to Embedded Systems: What is an embedded
system, Embedded System v/s General Computing System,
Classification of Embedded Systems, Major Application
Areas of Embedded Systems, Purpose of Embedded
Systems, Smart Running Shoes.
SKV – Ch 1: 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 Page 43 of 112 A
• Typical Embedded system: Core of the embedded system
SKV – Ch 2: 2.1
• Characteristics and quality Attributed of Embedded
Systems: Characteristics of an Embedded System, Quality
Attributes of Embedded Systems
SKV – Ch 3: 3.1, 3.2
UNIT – III: EMBEDDED SYSTEMS

• Embedded Systems-Application and Domain–Specific:
Washing Machine, Automatic Domain, Specific
examples of embedded system
SKV – Ch 4: 4.1, 4.2
• Design Process and design Examples: Automatic
Chocolate Vending machine (ACVM), Smart Card,
Digital Camera, Mobile Phone, A Set of Robots
RK - Ch 1: 1.10.2, 1.10.3, 1.10.4, 1.10.5, 1.10.6, 1.10.7
• Ref. SKV:- Introduction to embedded systems, by
Shibu K. V. ,Sixth Reprint 2012, Tata McGraw Hill
• Ref. RK:- “Embedded Systems” Architecture,
Programming and Design, by Raj Kamal, Second
Edition, The McGraw-Hill Companies

Introduction to Embedded
Systems
• What is an embedded system
• Embedded System v/s General Computing
System
• Classification of Embedded Systems
• Major Application Areas of Embedded
Systems
• Purpose of Embedded Systems
• Smart Running Shoes.

What is a system?
• Way of working , organizing or
doing one or more tasks according
to a fixed plan, program or set of
rules.
• An arrangement in which all its units
assemble & work together
according to plan or program.

What is a system?
• Example 1 : Time display system (watch)
 Objective : show & update real time every
second.
 Hardware :
o Needles
o Battery
o Chassis – base frame
o Strap
o Dial

What is a system?
• Example 1 : Time display system (watch)
Follows a set of rules.
• All needles move clockwise only.
• A seconds needle rotates every second
such that it returns to the same position
after one minute.
• A minutes needle rotates every minute
such that it returns to the same position
after one hour.

What is a system?
• Example 1 : Time display system
(watch)
• A hour needle rotates every hour
such that it returns to the same
position after twelve hours.
• All three needles return to the same
inclinations after twelve hours each
day.

What is a system?
• Example 2 : Automated clothes washing system
( washing machine)
• Objective : wash clothes automatically according to a
program preset by the user.
Hardware :
o Status display panel
o Switches & dials
o Motor to rotate & spin
o Power supply & control unit
o Water sensors
o Valves for draining water in and out.

What is a system?
• Example 2 : Automated clothes washing
system ( washing machine)
• Follows a set of rules.
• Wash by spinning the motor for a
preprogrammed period.
• Rinse in fresh water after draining out dirty
water, & rinse the second time if the
system is not programmed in water saving
mode.

What is a system?
• Example 2 : Automated clothes washing
system ( washing machine)
• At each step display the process stage of
the system.
• In case of an interruption, execute only
the remaining part of the process, starting
from the position when the process was
interrupted.

What is a system?
• Example 3: Air Conditioner
• An Air Conditioner from an embedded systems point
of view has:
a. Hardware: Remote, Display & buzzer, Infrared
sensors, electronic circuitry.
b. Software: It has a chip on the circuit that holds the
software which drives controls & monitors the various
operations possible. The software monitors the external
temperature through the sensors and then releases the
coolant or suppresses it.
c. Mechanical Components: The internals of an air
conditioner the motor, the chassis, the outlet, etc.

Introduction to embedded systems
• Computing systems are everywhere
• Most of us think of “desktop” computers
–PC’s
–Laptops
–Mainframes
–Servers
• But there’s another type of computing system
–Far more common...

A “short list” of embedded systems
• Anti-lock brakes
• Auto-focus cameras
• Automatic toll systems
• Automatic transmission
• Avionic systems
• Battery chargers
• Camcorders
• Cell phones
• Cell-phone base stations
• Cordless phones
• Cruise control
• Digital cameras
• Disk drives
• Electronic card readers
• Electronic instruments
• Scanners
• Smart
ovens/dishwashers
• Speech recognizers
• Stereo systems
• Teleconferencing
systems
• Televisions
• Temperature
controllers
• Theft tracking systems
• TV set-top boxes
• VCR’s, DVD players
• Video game consoles
• Video phones
• Washers and dryers
• Electronic toys/games
• Factory control
• Fax machines
• Fingerprint identifiers
• Home security systems
• Life-support systems
• Medical testing systems
• Modems
• Network cards
• Network switches/routers
• Pagers
• Photocopiers
• Portable video games
• Printers
• Satellite phones

1. “An embedded system is a system that has software embedded into
computer-hardware, which makes a system dedicated for an application (s) or
specific part of an application or product or part of a larger system.”
2. “ An embedded system is one that has a dedicated purpose software
embedded in a computer hardware.”
3. “ It is a dedicated computer based system for an application(s) or
product. It may be an independent system or a part of large system. Its
software usually embeds into a ROM (Read Only Memory) or flash.”
4. “ It is any device that includes a programmable computer but is not itself
intended to be a general purpose computer.”
5. “ Embedded Systems are the electronic systems that contain a
microprocessor or a microcontroller, but we do not think of them as
computers– the computer is hidden or embedded in the system.” – Todd
D. Morton
Embedded System : Definition

Introduction to embedded systems
• Embedded computing systems
–Computing systems embedded within
electronic devices
–Hard to define. Nearly any computing system
other than a desktop computer
–Billions of units produced yearly, versus
millions of desktop units
–Perhaps 50 per household and per automobile

Embedded systems
• “ Are electronic devices that incorporate
microprocessors within their
implementations”
• “ Specific or dedicated computing in many
electronic appliances, makes embedded
system”

Embedded systems
• A combination of computer hardware
& software.
• may include additional mechanical or
other parts.
• designed to perform a specific
function.
• Example : microwave oven.

Embedded systems
• Generally , an embedded system is a
component within some larger system.
• Example : Automobile industry
• One embedded system controls the anti-
lock brakes, another monitors and controls
the vehicle's emissions, and a third displays
information on the dashboard.
• May be connected by some sort of a
communications network .

History Of Embedded System
• The first recognized embedded system is the Apollo Guidance
Computer(AGC) developed by MIT lab.
• AGC was designed on 4K words of ROM & 256 words of RAM.
• The clock frequency of first microchip used in AGC was 1.024 MHz.
• The computing unit of AGC consists of 11 instructions and 16 bit word
logic.
• It used 5000 ICs.
• The UI of AGC is known DSKY(display/keyboard) which resembles a
calculator type keypad with array of numerals.
• The first mass - produced embedded system was guidance computer for
the Minuteman - I missile in 1961.
• In the year 1971 Intel introduced the world's first microprocessor chip
called the 4004, was designed for use in business calculators. It was
produced by the Japanese company Bussicom.

User Interface: UI of AGC
DSKY(display/keyboard)

Embedded System v/s General Computing System
Criteria General Purpose Embedded Systems
Contents It is combination of generic
hardware and a general
purpose OS for executing a
variety of applications.
It is combination of special
Purpose hardware and
embedded OS for executing
specific set of applications
Operating
System
It contains general purpose
operating system
It may or may not contain
operating system.
Alterations Applications are alterable
by the user.
Applications are non -alterable by
the user.
Key factor Performance is key factor Application specific requirements
are key factors
Power
Consumption
More Less
Response
Time
Not Critical Critical for some Applications

Personal computers
• comprised of computer hardware & software.
• mechanical components (disk drives)
• not designed to perform a specific function.
• able to do many different things.
• general-purpose computer

Personal computers
• A general-purpose computer is itself made up of
numerous embedded systems.
• Example :
• A computer consists of a keyboard, mouse, video
card, modem, hard drive, floppy drive, and sound
card-each of which is an embedded system.
• Each of these devices contains a processor &
software and is designed to perform a specific
function.
• A modem is designed to send & receive digital data
over an analog telephone line.

Embedded system: Block Diagram

Classification Of Embedded
System
The classification of embedded system
is based on following criteria's:
• On generation
• On complexity & performance
• On deterministic behavior
• On triggering

Classification: On generation
1.First generation(1G):
• Built around 8bit microprocessor & microcontroller.
• Simple in hardware circuit & firmware developed.
• Examples: Digital telephone keypads.
2. Second generation(2G):
• Built around 16 – bit μp & 8 – bit μc.
• They are more complex & powerful than 1G μp & μc.
• Examples: SCADA systems: Supervisory Control & Data
Acquisition System - SCADA systems are used to monitor and
control a plant or equipment in industries such as
telecommunications, water and waste control, energy, oil and gas
refining and transportation.

• Level 0 contains the field devices such as flow and temperature sensors, and
final control elements, such as control valves.
• Level 1 contains the industrialized input/output (I/O) modules, and their
associated distributed electronic processors.
• Level 2 contains the supervisory computers, which collate information from
processor nodes on the system, and provide the operator control screens.
• Level 3 is the production control level, which does not directly control the
process, but is concerned with monitoring production and targets.
• Level 4 is the production scheduling level.

Classification: On generation
3. Third generation(3G):
• Concepts like Digital Signal Processors(DSPs),
• Application Specific Integrated Circuits(ASICs) evolved.
• Examples: Robotics, Media, etc.
4. Fourth generation (4G) :
• The concept of System on Chips (SoC), Multicore Processors
evolved.
• Highly complex & very powerful.
• Examples: Smart Phones.

Classification - On Their Performance And
Functional Requirements
1. Stand Alone Embedded Systems:
• Do not require a host system like a computer, it works by itself.
• It takes the input from the input ports, processes, calculates gives the
resulting data through the connected device.
• Examples: mp3 players, digital cameras, video game consoles, microwave
ovens and temperature measurement systems.
2. Real Time Embedded Systems:
• System which gives a required o/p in a particular time.
• Follows the time deadlines for completion of a task.
• Classified into two types such as soft and hard real time systems.
• Examples: Vehicle systems for automobiles, subways, aircraft, railways, and
ships, process control for power plants, medical systems for radiation
therapy, telephone, radio, and satellite communications, computer games,
multimedia systems that provide text, graphic, audio, and video interfaces,
household systems for monitoring and controlling appliances, building
managers that control such entities as heat, lights, doors, and elevators

Classification - On Their Performance And
Functional Requirements
3. Networked Embedded Systems:
• Related to a network to access the resources like LAN, WAN or the
internet.
• The connection can be any wired or wireless.
• Example: The LAN networked embedded system in a home
security system wherein all sensors are connected.
4. Mobile Embedded Systems:
• Limitation is the other resources and limitation of memory.
• Examples: Portable embedded devices like cell phones, mobiles,
digital cameras, mp3 players and personal digital assistants, etc.

Classification: On Performance Of The
Microcontroller
• Small Scale embedded systems :
 Systems designed with a single 8 bit or 16
bit microcontroller.
 Little hardware & software complexities.
 Performance not time - critical.
 Battery operated.
 Board level design.

Microcontroller
• Small Scale embedded systems :
• Programming tools : editor, assembler, cross
assembler specific to microcontroller.
 C programming language.
 Software has to fit within the memory available.
 Limit power dissipation when the system is
running continuously.
 Example: Battery operated electronic toy

Microcontroller
• Medium scale embedded systems:
 Systems designed with a single or few 16 or 32
bit microcontrollers or DSP.
 Hardware & software complexities.
 Software design tools : C, C++, JAVA, Visual
C++, RTOS, Source code engineering tools ,
Simulators, debuggers, IDE’s (Integrated
Development Environment. Tools provided by
an IDE include a text editor, a project editor, a
tool bar, and an output viewer..)

Microcontroller
• Medium scale embedded systems:
 may employ readily available
Application Specific System processors
(ASSP) for various functions.
 Usually contain operating system.
 Examples: Industrial machines.

Microcontroller
• Sophisticated embedded systems:
• Enormous hardware & software complexities.
• Built around 32 or 64 bit RISC μp/μc or PLDs
(programmable logic devices – PROM, etc.)
• Used in applications that need hardware & software
co - design & integration in final system.
• Response is time - critical.
• Examples: Mission critical applications demanding
high performance.

Major Application Areas of Embedded
Systems
1. Embedded Systems in Automobiles and in telecommunications:
• Motor and cruise control system
• Body or Engine safety
• Entertainment and multimedia in car
• E-Com and Mobile access
• Robotics in assembly line
• Wireless Communication
• Mobile computing and networking
2. Embedded Systems in Smart Cards, Missiles and Satellites:
• Security systems
• Telephone and banking
• Defense and aerospace
• Communication

Major Application Areas of Embedded
Systems
3. Embedded Systems in Peripherals & Computer Networking:
• Displays and Monitors
• Networking Systems
• Image Processing
• Network cards and printers
4. Embedded Systems in Consumer Electronics:
• Digital Cameras
• Set top Boxes
• High Definition TVs
• DVDs

Purpose Of Embedded System
1. Data Collection/Storage/Representation:
• Embedded system designed for the purpose of data collection performs
acquisition of data from the external world.
• Data collection is usually done for storage, analysis, manipulation and
transmission.
• Data can be analog or digital.
• Embedded systems with analog data capturing techniques collect data directly
in the form of analog signal whereas embedded systems with digital data
collection mechanism converts the analog signal to the digital signal using
analog to digital converters.
• If the data is digital it can be directly captured by digital embedded system.
• A digital camera is a typical example of an Embedded System with data
collection/storage/representation of data.
• Images are captured and the captured image may be stored within the memory
of the camera. The captured image can also be presented to the user through a
graphic LCD unit.

2. Data Communication:
• Embedded data communication systems are deployed in
applications from complex satellite communication to simple
home networking systems.
• The transmission of data is achieved either by a wire – line
medium or by a wire – less medium.
• Data can either be transmitted by analog means or by digital
means.
• Wireless modules - Bluetooth, Wi - Fi.
• Wire - line modules - USB, TCP/IP.
• Network hubs, routers, switches are examples of dedicated data
transmission embedded systems.

3. Data Signal Processing:
• Embedded systems with signal processing functionalities are employed in
applications demanding signal processing like speech coding, audio video
codec, transmission applications, etc.
• A digital hearing aid is a typical example of an embedded system
employing data processing.
• Digital hearing aid improves the hearing capacity of hearing impaired
person
4. Monitoring:
• All embedded products coming under the medical domain are with
monitoring functions.
• Electro cardiogram machine is intended to do the monitoring of the
heartbeat of a patient but it cannot impose control over the heartbeat.
• Other examples with monitoring function are digital CRO, digital multi-
meters, and logic analyzers.

5. Control:
• A system with control functionality contains both sensors and actuators
(An actuator is a motor that converts energy into torque which then moves or
controls a mechanism or a system into which it has been incorporated. It can
introduce motion as well as prevent it. An actuator typically runs on electric or
pressure)
• Sensors are connected to the input port for capturing the changes in environmental
variable and the actuators connected to the output port are controlled according to the
changes in the input variable.
• Air conditioner system used to control the room temperature to a specified limit is a
typical example for CONTROL purpose.
6. Application specific user interface:
• Buttons, switches, keypad, lights, bells, display units etc are application specific user
interfaces.
• Mobile phone is an example of application specific user interface.
• In mobile phone the user interface is provided through the keypad, system speaker,
vibration alert, etc.

Smart Running Shoes: ADIDAS
Embedded
Hall Sensor

• Adidas created the world's first "smart shoe" by mating it with a computer
chip that adapts its cushioning level to a runner's size and stride.
• The Adidas 1 was the product of a three-year secret project the German
company developed at its U.S. headquarters in Portland, Ore.
• A shoe the company claimed will revolutionize distance running and
training.
• "This is the first intelligent shoe ever," said Erich Stamminger, global
marketing director for Adidas. "It senses, understands and adapts.“
• The computerized shoe endured the wear-and-tear of running in almost
any condition -- from hard pavement to dirt trails, and dry streets to wet
beaches.
• The entire assembly weighs no more than 40 grams -- just 10 percent of
the 400-gram total weight of the shoe, to keep it light enough for distance
runners.
• But the $250 price tag was likely to make it a luxury it.em

Set- up:
• Hall effect sensor at the top of “cushioning element”.
(A Hall effect sensor is a transducer that varies its output voltage in response to
a magnetic field. Hall effect sensors are used for proximity switching, positioning,
speed detection, and current sensing applications)
• Magnet at the bottom of the element
• Microprocessor positioned under the arch of the shoe
• Micro motor housed in the mid – foot
• Micro motor connected to a lead screw
• Screw connected to a cable secured to the walls of plastic cushioning element
• 3 V battery powers the motor and it lasts for 100 hours of running

Algorithm:
• As the cushioning compresses on each impact, the sensor measures the distance from top
to bottom of the mid – sole. (accuracy ≈ 0.1 mm)
• 1000 readings/ second taken and relayed to the embedded µP
• An embedded algorithm is run and compression values are compared to the preset ranges
of proper cushioning levels.
• µP commands the micro motor to turn the lead screw to either lengthen/ shorten the
cable.
• Shortened cable: less cushioning; longer cable: more cushioning
• Change in cushion element: accounts for – change of running surface, change in pace of
the runner
• Changes are made over 4 running steps, not to give sudden changes
• Inspite of automatic cushion adjustments changes needed – adjust using +/ - buttons
• LED indicates when the electronics of the shoe is turned on
• LEDs are off when shoe is in use
• If electronic part not switched on: shoe remains in normal regular mode
• If not used for more than 10 minutes shoe turns off

A Typical
Embedded system:
Core of embedded
system

• Embedded systems are domain and application
specific and are built around a central core.
• The core of the embedded system falls into any of
the following categories:
General purpose and domain specific processor.
 Microprocessors
 Microcontrollers
 Digital signal processors
Application Specific Integrated Circuits (ASIC)
Programmable logic devices(PLD’s)
Commercial off – the – shelf components(COTs)
Introduction

General purpose and domain specific processors
1.Microprocessors (µP)
• A microprocessor is a silicon chip representing a central
processing unit.
• It requires the combination of other hardware like memory,
timer unit, interrupt controller, etc. for proper functioning.
• Developers of microprocessors:
• Intel – Intel 4004 – November 1971(4 - bit).
• Intel – Intel 4040
• Intel – Intel 8008 – April 1972.
• Intel - Intel 8080 – April 1974(8 - bit).
• Motorola – Motorola 6800.
• Intel – Intel 8085 –1976.
• Zilog - Z80 – July 1976

Microprocessors (µP)
• Intel
• Motorola
• AMD
• FreeScale
• IBM
• Hitachi
• NES
• Cyrix

2. Microcontrollers (µC)
• Highly integrated chip that contains a CPU, scratch pad RAM,
special and general purpose register arrays,on chip ROM/FLASH
memory for program storage , timer and interrupt control units
and dedicated I/O ports.
• Texas Instrument’s TMS 1000 Is considered as the world’s first
microcontroller.
• Some embedded system application require only 8 bit controllers
whereas some requiring superior performance and computational
needs demand 16/32 bit controllers.
• The instruction set of a microcontroller can be RISC or CISC.
• Microcontrollers are designed for either general purpose
application requirement or domain specific application
requirement

Microcontrollers (µC)
• Intel
• PIC – (Peripheral Interface Controller)
• Atmel
• Zilog
• Freescale
• Toshiba
• Philips
• Texas Instruments
• Daewoo
• TDK
• Triscend

Microprocessor Microcontroller
Block diagram of microcontroller
Contains ALU, General purpose registers, stack
pointer, program counter, clock timing circuit,
interrupt circuit
Contains the circuitry of microprocessor, and in
addition it has built in ROM, RAM, I/O Devices,
Timers/Counters etc.
It has many instructions to move data between
memory and CPU
It has few instructions to move data between
memory and CPU
Few bit handling instruction It has many bit handling instructions
Less number of pins are multifunctional More number of pins are multifunctional
Single memory map for data and code (program) Separate memory map for data and code (program)
Access time for memory and IO are more Less access time for built in memory and IO
It requires more additional hardware It requires less additional hardware
More flexible in the design point of view Less flexible since the additional circuits reside
inside the microcontroller
Large number of instructions with flexible
addressing modes
Limited number of instructions with few addressing
modes

RISC AND CISC CPU ARCHITECTURES
Microcontrollers with small instruction set are called reduced instruction set computer
(RISC) machines . Example: Microchip PIC 18F87X
Microcontrollers with complex instruction set are called complex instruction set
computer (CISC). Example: Intel 8051
•
RISC CISC
Instruction takes one or two cycles Instruction takes multiple cycles
Instructions executed by hardware Instructions executed by the micro program
Fixed format instruction Variable format instructions
Few addressing modes Many addressing modes
Few instructions Complex instruction set
Have multiple register banks Single register bank
Highly pipelined Less pipelined
Complexity is in the compiler Complexity in the microprogram

Harvard architecture Von Neumann architecture
The name is originated from “Harvard
Mark I” a relay based old computer.
It is named after the mathematician and early
computer scientist John Von Neumann.
It required two memories for their
instruction and data
It required only one memory for their
instruction and data
Design of Harvard architecture is
complicated.
Design of the von Neumann architecture is
simple.
Harvard architecture is required
separate bus for instruction and data.
Von Neumann architecture is required only one
bus for instruction and data.
Comparatively high cost. It is cheaper.
Uses CISC architecture Uses RISC architecture
Eg. 8085, 8086, MC6800 Eg. General purpose microcontrollers, special
DSP chips etc.

Digital signal processors (DSP)
• powerful , special purpose 8/16/32 bit
processors designed to meet computational
demands & power constraints of today’s
embedded audio , video & communication
applications.
• DSP are two or three times faster than
general purpose µP in signal processing
applications.

• A microprocessor incorporates the functions of a
computer's central processing unit (CPU) on a single
or few integrated circuits. The purpose of a
microprocessor is to accept digital data as input,
process it as per the instructions, and then provide
the output. This is known as sequential digital logic.
The microprocessor has internal memory and
operates basically on the binary system. Most
general purpose microprocessors are present in
personal computers. They are often used for
computation, text editing, multimedia display, and
communication over a network.

• The DSP processor, on the other hand, is a
particular type of microprocessor. It is basically
any signal processing that is done on a digital
signal or information. A DSP processor is a
specialized microprocessor that has an
architecture optimized for the operational needs
of digital signal processing.DSP aims to modify or
improve the signal. It is characterized by the
representation of discrete units, such as discrete
time, discrete frequency, or discrete domain
signals. DSP includes subfields like
communication signals processing, radar signal
processing, sensor array processing, digital image
processing, etc.

• The main goal of a DSP processor is to
measure, filter and/or compress digital or
analog signals. It does this by converting
the signal from a real-world analog signal
to a digital form. In order to convert the
signal it uses a digital-to-analog
converter (DAC). However, the required
output signal is often another real-world
analog signal. This is turn also requires a
digital-to-analog converter.

• The main difference between a DSP and a
microprocessor is that a DSP processor has features
designed to support high-performance, repetitive,
numerically intensive tasks. DSP processors are
designed specifically to perform large numbers of
complex arithmetic calculations and as quickly as
possible. They are often used in applications such as
image processing, speech recognition and
telecommunications. As compared to general
microprocessors, DSP processors are more efficient
at performing basic arithmetic operations, especially
multiplication.

• Most general-purpose microprocessors and
operating systems can execute DSP algorithms
successfully. However, they are not suitable for
use in portable devices such as mobile phones.
Hence, specialized digital signal processors are
used. Digital Signal Processors have
approximately the same level of integration and
the same clock frequencies as general purpose
microprocessors, but they tend to have better
performance, lower latency, and no requirements
for specialized cooling or large batteries. This
allows them to be a lower-cost alternative to
general-purpose microprocessors.

• DSPs also tend to be two to three times as fast
as general-purpose microprocessors. This is
because of architectural differences. DSPs
tend to have a different arithmetic Unit
architecture; specialized units, such as
multipliers, etc.; regular instruction cycle, a
RISC-like architecture; parallel processing; a
Harvard Bus architecture; an Internal memory
organization; multiprocessing organization;
local links; and memory banks
interconnection.

• Digital signal processing algorithms can run on
various platforms, such as general purpose
microprocessors and standard computers;
specialized processors called digital signal
processors (DSPs); purpose-built hardware
such as application-specific integrated circuit
(ASICs) and field-programmable gate arrays
(FPGAs); Digital Signal Controllers; and stream
processing for traditional DSP or graphics
processing applications, such as image, video.

• Program memory: for storing the program required by DSP to
process the data.
• Data memory: working memory for storing temporary
variables and data/signal to be processed.
• Computational engine:
 performs the signal processing in accordance with the stored
program memory
 incorporates many specialized arithmetic units and each of
them operates simultaneously to increase the execution
speed.
 includes multiple hardware shifters for shifting operands and
saves execution time.

• I/O units:
acts as an interface between the outside world
and DSP.
responsible for capturing signals to be processed
and delivering the processed signals.
• Applications
 Audio video signal processing
 Telecommunications
 Multimedia

Big endian & Little endian
processors
• Endianness specifies the order in which data
is stored in memory by processor operations
in a multi byte system.
• Example : Assume a word length is 2 bytes.
Data can be stored in memory in two ways.

Big endian & Little endian
processors
• Higher order of the data byte at higher
memory & lower order of the data byte at
location just below the higher memory.
• Lower order of the data byte at higher
memory & higher order of the data byte at
location just below the higher memory.

Little Endian
• Lower order byte of data is stored in memory
at the lowest address & the higher order byte
at the highest address.
• Little end comes first.
• Example : A four byte long integer Byte 3 ,
Byte 2 , Byte 1 , Byte 0 is stored as follows.

Little Endian
Byte 0
Byte 1
Byte 2
Byte 3
0x20000 (base
address)
Base address + 0
0x20001
0x20002
0x20003
Base address + 1
Base address + 2
Base address + 3

Big Endian
• Higher order byte of data is stored in memory
at the lowest address & the lower order byte
at the highest address.
• Big end comes first.
• Example : A four byte long integer Byte 3 ,
Byte 2 , Byte 1 , Byte 0 is stored as follows.

Big Endian
Byte 3
Byte 2
Byte 1
Byte 0
0x20000 (base
address)
Base address + 0
0x20001
0x20002
0x20003
Base address + 1
Base address + 2
Base address + 3

Application Specific IC (ASIC)
• A microchip designed to perform a specific or
unique application.
• used as a replacement to conventional
general purpose logic chips.
• reduces system development cost by
integrating several functions into a single chip.

Application Specific IC (ASIC)
• Consumes very small area in total system and
helps in design of smaller systems with high
capabilities/functionalities.
• profitable only for large volume commercial
productions.
• Fabrication of ASIC requires reqires non
refundable initial investment known as NRE.

Programmable Logic devices (PLD)
• Logic device provide specific functions.
 Device to device interfacing.
 Data communication
 Signal processing
 Data display
 Timing & control operations.
• Two categories : fixed & programmable.

• Fixed
 circuits in a fixed logic device are permanent.
 one function or set of functions.
• Programmable Logic devices
 wide range of features, speed , voltage
characteristics , logic capacity.
 reconfigured to perform any number of
functions at any time.

• designers can use inexpensive software tools
to quickly develop, simulate & test their
designs.
• can be used & tested in a live design.
• No NRE costs.
• During the design phase, circuitry can change
as often as they want until the design
operates to their satisfaction.

• PLD’s are based on rewritable memory technology
(to change the design the device is reprogrammed).
• CPLD & FPGA are two major types of PLD’s
• Complex programmable logic device ,is also other
type of digital logic chip but has less complex
architecture and contains only few blocks of logic
that reaches upto few thousand.
• Field – Programmable Gate Array, is a type of
programmable logic chip has more complex
architecture and contains upto 100,000 of tiny logic
blocks.

• Advantages
• 1) PLDs offer customer much more flexibility
during the design cycle.
• 2) PLDs do not require long lead times for
prototypes or production parts because PLDs
are already on a distributors shelf and ready
for shipment.
• 3) PLDs can be reprogrammed even after a
piece of equipment is shipped to a customer

COTS
• COTS : Commercial Off-the Shelf
• Product is used as it is.
• Designed to provide easy integration with
existing system components.
• COTS component may be developed around
general purpose or domain specific processors
or ASIC , PLD.

COTS
• Examples
• Remote control toy car
• RF circuitry part.
• High performance, high frequency microwave
electronics.
• High BW A to D convertors.
• UV/IR detectors.

COTS
• Advantages
 Readily available.
 Cheap
 Developer can cut development time to a
great extent.
 Reduces the time to market the embedded
system.

COTS
• Limitations:
 manufacturer of CTOS components may
withdraw the product or discontinue the
production at any time because of rapid
change in technology.
 affect the commercial manufacturer of the
embedded system which make use of specific
CTOS product.

Characteristics &
Quality attributes

Objectives
• Characteristics of embedded systems.
• Quality attributes of embedded systems.
• Application specific embedded systems :
Washing Machine, Microwave Owen
• Domain specific embedded systems :
Automotive.

Characteristics
• Application and domain specific
• Reactive & Real time
• Operates in Harsh environment.
• Distributed.
• Small size & weight.
• Power concerns.

Characteristics : Application and
domain specific
• Each embedded system is designed to perform
an intended task.
• cannot be used for any other purpose.
• major criteria that separates an embedded
system from a general purpose system.

Characteristics : Application and
domain specific
• Example :
• Cannot replace the control unit of your
microwave oven with your air conditioner’s
control unit , because the control units of both
are designed to perform certain specific tasks.
• cannot replace an embedded control unit
developed for a specific domain (telecom) with
another control unit designed to serve another
domain( consumer electronics)

Characteristics : Reactive & Real time
• Embedded systems are in constant interaction
with real world through sensors & other input
devices which are connected to the input port.
• Any changes are captured by sensors or input
devices in real time & the control algorithm
reacts in a desired manner to control output
variable to a desired variable.

• Embedded system produce changes in output
in response to the changes in input.
• Reactive.
• Real time operation means the timing
behavior of the system must be deterministic.

• System must respond to tasks in a known amount
of time.
• not miss any deadlines.
• Worst case scenario into consideration.
• Examples:
o Flight control systems
o Anti Brake systems.

Characteristics : Harsh environment
operation
• Not necessary that an embedded system
should be designed for controlled
environment.
• Dusty , high temperature zone, areas subject
to vibrations or shock.
• Such systems must be able to withstand
adverse operating conditions.

operation
• Example:
• If the system is designed in high temperature
zone, then the components used must be able
to withstand high temperatures.
• Shock absorption techniques must be
provided to systems commissioned in places
subject to high shock.

operation
• Example:
• Power supply fluctuations.
• Corrosion
• Component aging.

Characteristics : Distributed
• Embedded systems are part of larger systems.
• Example:
 Automatic Teller Machine (ATM)
o card reader for reading & validating user’s card.
o Transaction unit for performing transactions.
o Currency unit for dispatching/vending currency.
o Printer unit for printing transaction details.
• Independent systems connected to achieve a
common goal.

Characteristics : Small size & weight
• Size , weight , shape , style may an important
role in choosing a product.
• Convenient to handle a compact device
rather than a bulky one.

Characteristics : Power
• minimize heat dissipation by the system.
• Cooling requirement for high heat dissipation
requires additional space which makes the
system bulky.
• critical for battery operated applications.

Quality attributes
• Non functional requirements that need to be
documented in any system design.
• If the quality attributes are more concrete &
measurable it gives a +ve impact on system
development process & end product.
• Operational Quality attributes
• Non Operational Quality attributes

Operational Quality attributes
• relevant quality attributes when the
embedded system is in operational mode or
online mode.
 Response
 Throughput
 Reliability
 Maintainability
 Security
 Safety

Response
• Measure of quickness of the system.
• how fast the system tracks changes in input
variables.
• Most embedded systems demand fast
response which should be almost real time.

Response
• Example:
 An embedded system deployed in flight
control application should response in real
time manner.
 Any response delay can cause potential threat
to the safety of the flight & passengers.
 On the other hand response time req. for an
electronic toy is not at all time critical.

Throughput
• efficiency of the system.
• defined as a rate of production or operation
of a defined process over a period of time.
• Rates can be expressed in terms of units of
products, batches produced etc.

Throughput
• Example : Card reader
• How many transactions can it produce in a
minute or in a hour or in a day.
• Generally measured in terms of Benchmark.
A reference point by which something can be
measured.
Can be a set of performance criteria that a
product is expected to meet.

Reliability
• is a measure of how much percent the system
is reliable or what is the percentage of the
system to failures.
• Mean Time Between Failures (MTBF) & Mean
Time To Repair (MTTR) are the terms used in
defining system reliability.

Reliability
• MTBF gives the frequency of failures in
hours/weeks/months.
• MTTR specifies how long the system is
allowed to be out of order following the
failure.
• For an embedded system with critical
application need , order of minutes.

Maintainability
• Support & maintenance to the end user in
case of technical issues , product failures or on
the basis of routine system check up.
• A more reliable system means a system with
less corrective maintainability requirements &
vice versa.

Maintainability
• As the reliability of the system increases,
chances of failures & non functioning also
reduces , thereby the need of maintainability
is reduced.
• Two categories
 Scheduled or periodic maintenance.
 Maintenance to unexpected failures.

Maintainability
• Scheduled or periodic maintenance.
 Consumable components or components
which are subject to wear & tear & should be
replaced on a periodic basis.
 period may be based on total hours of system
usage or the total output of the system
delivered.

Maintainability
• Example: Ink Jet printer
 uses ink cartridge which are consumable
components & must be replaced after n
printouts to get quality output. (Scheduled or
Periodic maintenance)
 If the paper feeding part of the printer fails
the printer fails to print & it requires
immediate repairs to rectify this problem.
(Maintenance to unexpected failure)

Maintainability
• In both of the maintenances, the printer
needs to be offline & during this time it is not
available to the end user.
• Ideal value for availability is expressed as :
• Ai = MTBF/(MTBF + MTTR)
• Ai is availability in ideal condition.

Security
• Three major measures of information security.
 Confidentiality
 Integrity
 Availability
• Confidentiality : protection of data &
application from unauthorized disclosure.

Security
• Example : Personal Digital Assistant (PDA)
 either a shared resource or a individual one.
 In a shared resource, some mechanism in
form of user name & password is needed to
access a person’s profile. An e.g. of Availability
 All data & applications need not be accessible
to all users.
 Can implement Administrator & User level
securities . An e.g. of Confidentiality.

Security
• Some data may be visible to all users, but
there may not be necessary permissions to
alter data by users.
• Read only access allotted to users.
• An e.g. of Integrity.

Safety
• Deals with possible damages that can happen
to operators, public , environment due to
breakdown of the system or due to emission
of radioactive or hazardous materials from the
embedded system.
• breakdown could occur due to hardware
failure or firmware.

Safety
• Safety analysis is a must in product
engineering to evaluate anticipated damages
& determine the best course of action to bring
down the consequences of damages to an
acceptable level.

Non Operational Quality
attributes
• Testing & Debugging
• Evolvability
• Portability
• Time to prototype and market
• Per unit and total cost.

Testing & Debugging
• Testing : how easily the design can be tested
and how.
• Applicable to both Hardware & firmware.
• Hardware testing ensures that the peripherals
& total hardware functions in a desired
manner.

Testing & Debugging
• Firmware testing ensures that the firmware is
functioning in an expected way.
• Debugging :
 debugging the product for probable sources
that create unexpected behavior of the
system.
 Hardware level & firmware level debugging.

Evolvability
• refers to the ease with which the embedded
system can be modified to take advantage of
hardware or firmware technologies.
• Hardware.
• Firmware.

Time to market design metric
• Most of the metrics are heavily constrained.
• Time to market : demanding in recent years.
• Introduction of an embedded system early in
the market can make a big difference to
profitability.

Time to market design metric
•Sample market window
revenue
months

Losses due to delayed market entry
•
On-time Delayed
entry entry
Peak revenue
Peak revenue from delayed entry
Market rise Market fall
W 2W
Time
D
On-time
Delayed
Revenues
(Rs)

Losses due to delayed market
entry
• Simplified revenue model
• Assumes : Peak of the market occurs at half
way point & peak is same even for delayed
entry.
–Product life = 2W, peak at W.
– On Time : revenue generated when the
product enters the market on time.

entry
• Delayed :revenue generated when the product
enters the market late.
• Revenue Loss for delayed entry:
The difference between the on-time &
delayed triangle areas.

entry
• Percentage revenue loss:
• (On time - Delayed) / on Time * 100
• Assumption : Market rise angle is 45⁰.
• Height of the triangle is W.

entry
• Area of On Time triangle : 0.5 * base * height
• 0.5 * 2W * W = W2
• Area of Delayed triangle :
• 0.5 * ( W – D + W) * (W – D)

entry
• Percentage revenue loss:
• ( D (3W – D )/ 2W2 ) * 100 %
• Example : Consider a product whose life
time is 52 weeks , so W = 26.
• A delay of just 4 weeks (D = 4) results in a
revenue lost of 22 %.
• A delay of 10 weeks (D = 10) results in a
revenue lost of 50 %.

NRE & Unit Cost design Metrics
• Assume three technologies are available for
use in a particular product.
Technology NRE cost Unit Cost
A $2000/- $100
B $30000/- $30
C $100000/- $2

• Ignore all other design metrics.
• Technology choice would then depend on the
number of units that need to be produced.
• Plot of total cost ( y axis) v/s number of units
produced yields the following results.

• total cost = NRE cost + (unit cost * number of
units)
• Technology A yields the lowest total cost for
low volumes. ( 1 to 400).
• Technology B yields the lowest total cost for
volumes between 400 to 2500.

• Technology C yields the lowest total cost for
volumes above 2500.
• per product cost = total cost/ no of units
• NRE cost/ no of units + unit cost

• For technology C and volume of 200,000
• NRE cost = 100000/200000 = $0.50
• Per product cost = $0.50 + 2 = $2.50
• Larger the volume, lower the per-product
cost, since NRE cost can be distributed over
more products.

• Per-product cost for each technology
approaches that technology’s unit cost for
very large volumes.
• One must consider the revenue impact of
both time-to market & per-product cost as
well as other relevant design metrics when
evaluating different technologies.

Application specific embedded
systems
• Example : Washing machine
• Provides extensive support in home
automation applications.
• contains sensors, actuators, control unit &
application specific user interfaces like
keyboards, display unit.

systems
• Some of these components are visible & some
invisible.
• Actuator part
 tumble tub
 Motorized agitator
 water drawing pump
 inlet valve to control flow of water into the
unit.

systems
• Sensor part
 Water temperature sensor
 level sensor
• Sensor part
 µP/ µC based board with interfaces to sensors
& actuators.

systems
• Sensor data is fed back to the control unit &
the control unit generates the necessary
actuator outputs.
• Control unit also provides connectivity to user
interfaces like keypad for setting the washing
time , selecting the type of material to be
washed (light , medium , heavy)

systems
• User feedback is through display units & LED’s
connected to the control board.
• Two models
 Top loading
 Front loading

systems
• Top loading : Agitator of the machine twists
back & forth & pulls the cloth to the bottom of
the tub. On reaching the bottom clothes work
their way back up to the top & the process
repeats.
• Front loading : Clothes are tumbled &
plunged into water over and over again.
• First phase of washing.

systems
• Second Phase :
 Water is pumped out of the tub & the inner
tub uses centrifugal force to rinse more water
from the clothes by spinning at several
hundred rotations per minute.
 Spin phase.

systems
• Basic controls
 Timer
 Cycle selector mechanism.
 Water temperature selector
 load size selector
 Start button.

systems
• Integrated control panel consists of µP/ µC
based board with I/O interfaces & a control
algorithm running in it.
• Input interface includes keyboard which
consists of wash type selector, cloth type
selector, wash time settings etc.

systems
• The output interface consists of LED/LCD
displays, status indication, LED’s etc.
connected to the I/O bus of the controller.
• Interface may wary from manufacturer to
manufacturer.

A microwave oven consists of:
• A high voltage transformer, which
passes energy to the magnetron
• A cavity magnetron,
• A Control circuit with a microcontroller,
• A waveguide,
• A cooking chamber

• Transformer - transfers electrical energy
through a circuit by magnetic coupling
without using motion between parts which
are used for supplying power to the
magnetron.
• Cavity magnetron - a microwave antenna
placed in a vacuum tube and oscillated in
an electromagnetic field in order to
produce high GHz microwaves.
• Magnetrons are used in microwave ovens
and radar systems.

• Control circuit with a microcontroller is
integrated on a circuit board.
• The microcontroller controls the waveguide
and the entire unit so the microwaves are
emitted at a constant rate.
• Waveguide is any linear structure that
guides electromagnetic waves for the
purpose of transmitting power or signals
constructed of a hollow metal pipe.

• Cooking Chamber - a microwave safe container
the prevents microwaves from escaping.
• The door has a microwave proof mesh with holes
that are just small enough that microwaves can't
pass through but light waves can.
• The cooking chamber itself is a Faraday cage
enclosure which prevents the microwaves from
escaping into the environment.
• The oven door is usually a glass panel for easy
viewing, but has a layer of conductive mesh to
maintain the shielding.

Domain specific embedded systems
• Automotive embedded systems.
 electronics take control over mechanical
systems.
 Presence of automotive embedded systems
varies from simple mirror to wiper controls to
complex air bag controllers and anti brake
systems.

Domain specific embedded
systems
• Automotive embedded systems are built
around microcontrollers or DSP or a hybrid of
the two & are generally known as ECU.
• No of embedded controllers in an ordinary
automobile varies from 20 to 40 whereas in a
luxury vehicle there may be 75 to 100
embedded controllers.

systems
• Government regulations on fuel economy,
environmental factors, emission standards &
increasing customer demands on safety ,
comfort force the automobile manufacturers
to have sophisticated embedded control units
within their vehicle.

Some of the other uses of
embedded controllers in a vehicle
• Air Conditioner
• Engine Control
• Fan Control
• Headlamp Control
• Automatic break system control
• Wiper control
• Air bag control
• Power Windows

systems
• ECU’s can be classified into two
 High-speed embedded control unit (HECUs)
 Low-speed embedded control unit (LECUs)
• High-speed embedded control unit (HECUs)
 deployed in critical control units requiring a
fast response.
 fuel injection, antilock brake , engine control,
steering controls, transmission control unit .

systems
• Low -speed embedded control unit (LECUs)
 deployed in applications where the response
time is not so critical.
 Built using low cost µC and DSP.
 Audio controllers, passenger & drive door
locks, power windows, wiper control, mirror
control, seat control systems head & tail lamp
controls , sun roof control etc.

Automotive Communication Buses
• Embedded system used inside an automobile
communicate with each other using serial buses. This
reduces the wiring required.
• Different types of serial Interfaces used in automotive
embedded applications:
• Controller Area Network (CAN):
• CAN bus was originally proposed by Robert Bosch.
• It supports medium speed and high speed data transfer
• CAN is an event driven protocol interface with support
for error handling in data transmission.

Local Interconnect Network (LIN):
• LIN bus is single master multiple slave
communication interface with support for
data rates up to 20 Kbps and is used for
sensor/actuator interfacing
• LIN bus follows the master communication
triggering to eliminate the bus arbitration
problem that can occur by the simultaneous
talking of different slave modes connected to
a single interface
• LIN bus applications are mirror controls, fan
controls, seat positioning controls

Media - Oriented System Transport
(MOST)
• MOST is targeted for automotive audio/video
equipment interfacing used in European cars
• A MOST bus is a multimedia fiber optics point
– to - point network implemented in a star,
ring or daisy chained topology over optical
fiber cables.
• MOST bus specifications define the physical as
well as application layer, network layer and
media access control.

DESIGN PROCESS EXAMPLES
• Automatic Chocolate vending machine

EMBEDDED SYSTEMS - MSc Sem III (Final).ppt

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