DEPT & SEM ECE & VII

:
EMBEDDED SYSTEMS
SUBJECT NAME
: ES

COURSE CODE I
:
L MAHESH
UNIT :

PREPARED BY :
 OUTLINE-INTRODUCTION TO EMBEDDED SYSTEMS

• Definition of Embedded System

• Embedded System Vs General Computing Systems
• History of Embedded Systems
• Classification of embedded systems
• Major Application Areas
• Characteristics of embedded systems
• Quality Attributes of Embedded Systems

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 INTRODUCTION

A system is a way of working organizing

or doing one or many tasks according to
a fixed plan, program or set of rules.

A system is also an arrangement in

which all its units assemble and work
together according to the plan or program.

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 SYSTEM
EXAMPLES
WATCH
It is a time display SYSTEM
Parts: Hardware, Needles, Battery, Dial, Chassis and Strap
Rules
1. All needles move clockwise only
2. A thin needle rotates every second
3. A long needle rotates every minute
4. A short needle rotates every hour
5. All needles return to the original position after 12
hours COURSE:ES UNIT: I Pg. 4
SYSTEM
EXAMPLES
WASHING MACHINE
It is an automatic clothes washing SYSTEM
Parts: Status display panel, Switches & Dials, Motor, Power
supply & control unit, Inner water level sensor and
solenoid valve.
Rules
1.Wash by spinning
2.Rinse
3. Drying
4. Wash over by blinking
5. Each step display the process stage
6. In case interruption, execute only the remaining COURSE:ES UNIT: I Pg. 5
 INTRODUCTION

1.1 What is an Embedded Systems?

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1.2 Embedded System Vs General Computing Systems

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1.3 History of Embedded system

Here, are important milestones from the history of embedded system:

In 1960, embedded system was first used for developing Apollo Guidance System by
Charles Stark Draper at MIT.

In 1965, Autonetics, developed the D-17B, the computer used in the Minuteman
missile guidance system.

1971- Intel 4004 released: First commercial microprocessor

1980s- Embedded systems widely used in consumer electronics (TVs, washing

machines)

1990s- Introduction of real-time operating systems (RTOS)

2000s–Present- Rapid growth in IOT (Internet of Things), wearable's, automobiles,

and smart devices

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Apollo Guidance System

The first recognizably modern embedded system.

Developed by Charles Stark Draper at the MIT Instrumentation Laboratory
Used in real time astronaut pilots to collect and provide flight information.
Automatically control all of the navigational functions of the Apollo spacecraft.
The Apollo flight computer was the first to use integrated Circuits (ICs).
The computer’s RAM was magnetic core memory (4K words) and ROM was implemented
as core rope memory (32K Words)

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D-17 Guidance Computer

The first mass-produced embedded system developed for Minuteman missile.

Built from discrete transistor logic and had a disk for main memory.

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1.4 Classification of Embedded Systems

 Based on Generation.

Complexity and Performance Requirements.

 Based on Deterministic Behaviour

Based on Triggering.

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Based On Generation

 First Generation:
 Earlier embedded systems which were built using 8 bit Microprocessors and
4-bit Microcontrollers come under this category.

 8085, Z80 and 4-bit Microcontrollers SIC60 family from EPSON, EM6607
from EM Microelectronics etc…

 Simple in hardware circuits with firmware developed in Assembly

Language.

 Digital Telephone keypads, Stepper motor Control Units etc are example
of this generation.

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 Second Generation:

 Earlier embedded systems which were built using 16-bit

Microprocessors and 8-bit Microcontrollers come under this
category.
 8086, Z800 and 8-bit Microcontrollers 8051family from Atmel, At
mega, Philips etc..
 Complex in hardware circuits with more complex instruction
set compared to first generation systems with some containing
operating systems for their operations.
 Data Acquisition System, SCADA Systems are example
of this generation.
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 Third Generation:
 Embedded systems which are built using 32-bit Microprocessors and 16-bit
Microcontrollers come under this category.
 A new concept of Application specific and domain specific
processor/controllers like DSP Processors and Application specific Integrated
Circuits came into picture.
 Instruction sets became more complex and powerful with an introduction of Instuction
pipelining concept introduced.
 Processors like Intel, Pentium, Motorola 68k gained attention in high performance
embedded requirement.
 Dedicated Embedded real-time and general purpose
operating systems enter into the market.
 Robotics, Media, Industrial Process Control, networking
etc….are example of this generation.

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  Fourth Generation:
 With the advent of System on Chip SoC, reconfigurable
processors and multicore processors are bringing high
performance, tight integration and miniaturisation into the
embedded device market.
 The SoC technique implements a total system on a chip by
integrating different
functionalities with a processor core on an integrated circuit.
 They make use of high performance real time embedded
operating systems for their functioning.
 Smart Phone devices, Mobile Internet
Devices(MIDs) etc are examples of this
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 CLASSIFICATIONS OF
EMBEDDED SYSTEM

1. Small Scale Embedded System

2. Medium Scale Embedded System

3. Large Scale Embedded System

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SMALL SCALE EMBEDDED SYSTEMS

 They are built using low performance, low cost 8 or

16-bit Microprocessor/Microcontrollers.
 They may or may not contain an operating system
for their functioning.
 Simple in application need and performance is not
time critical.
 An electronic toy is an example of it.

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MEDIUM SCALE EMBEDDED SYSTEMS

 Systems are built around medium performance an low

cost 16 or 32-bit microprocessors or microcontrollers
or Digital signal processors.
 They usually contain an operating system (general
purpose or real time operating system) for its
functioning.
 Slightly complex in hardware and firmware(software)
requirements.
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LARGE SCALE EMBEDDED SYSTEMS

 They are built around 32 or 64-bit RISC processors/controllers or

Reconfigurable System on Chip RSoC or multi-core processors and
programmable logic devices.
 They involve highly complex hardware and firmware in this category.
 They may contain multiple processors/controllers and co- units/hardware
accelerators for offloading the processing requirements from the main
processor of the embedded system.
 They are employed in mission critical applications which demands high
performance.
 They contain real time operating system for task scheduling, prioritization
and management.

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Embedded Systems - Classification Based on deterministic
behavior: It is applicable for Real Time systems. The
application/task execution behavior for an embedded system can be
either deterministic or non- deterministic
These are classified in to two types
1.Soft Real time Systems: Missing a deadline may not be critical
and can be tolerated to a certain degree
2.Hard Real time systems: Missing a program/task execution time
deadline can have catastrophic consequences (financial, human loss
of life, etc.)

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Embedded Systems Classification Based on Triggering:
These are classified into two types

1.Event Triggered : Activities within the system (e.g., task

run-times) are dynamic and depend upon occurrence of
different events .
2.Time triggered: Activities within the system follow a
statically computed schedule (i.e., they are allocated time
slots during which they can take place) and thus by nature
are predictable.
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1.5 Major Application Areas of Embedded Systems

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CHARACTERISTICS OF EMBEDDED SYSTEMS

Application and domain specific

 Reactive and Real Time

Operates in harsh environments

Distributed

Small Size and weight

Power concerns

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APPLICATION AND DOMAIN SPECIFIC

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REACTIVE AND REAL TIME

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OPERATES IN HARSH ENVIRONMENTS

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DISTRIBUTED

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SMALL SIZE AND WEIGHT

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POWER CONCERNS

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QUALITY ATTRIBUTES OF EMBEDDED SYSTEMS
There are two types of quality attributes are:-

1. Operational Quality Attributes.

⚫ These are attributes related to operation or functioning of an embedded system. The way
an embedded system operates affects its overall quality.

2. Non-Operational Quality Attributes.

⚫ These are attributes not related to operation or functioning of an embedded system. The
way an embedded system operates affects its overall quality.

⚫ These are the attributes that are associated with the embedded system before it can be
put in operation.

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OPERATIONAL ATTRIBUTES

a) Response :
Response is a measure of quickness of the system.
 It gives you an idea about how fast your system is tracking the input
variables.
 Most of the embedded system demand fast response which should be real-
time.

b) Throughput
Throughput deals with the efficiency of system.
It can be defined as rate of production or process of a defined process over a
stated period of time.
 In case of card reader like the ones used in buses, throughput means how
much transaction the reader can perform in a minute or hour or day.

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c) Reliability:
⚫ Reliability is a measure of how much percentage you rely upon the proper
functioning of the system.

⚫ Mean Time between failures and Mean Time To Repair are terms used in defining
system reliability. ⚫ Mean Time between failures can be defined as the average time
the system is functioning before a failure occurs.

⚫ Mean time to repair can be defined as the average time the system has spent in
repairs.

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d) Maintainability:
⚫ Maintainability deals with support and maintenance to the end user or a client in case of
technical issues and product failures or on the basis of a routine system checkup
⚫ It can be classified into two types :-
1. Scheduled or Periodic Maintenance

This is the maintenance that is required regularly after a periodic time interval.
Example :
⚫ Periodic Cleaning of Air Conditioners
⚫ Refilling of printer cartridges.

2. Maintenance to unexpected failure :

⚫ This involves the maintenance due to a sudden breakdown in the functioning of the
system.
⚫ Example: 1. Air conditioner not powering on
2. Printer not taking paper in spite of a full paper stack

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e) Security:
⚫ Confidentiality, Integrity and Availability are three corner stones of information
security.

⚫ Confidentiality deals with protection data from unauthorized disclosure.

⚫ Integrity gives protection from unauthorized modification.

⚫ Availability gives protection from unauthorized user

⚫ Certain Embedded systems have to make sure they conform to the security
measures. Ex. An Electronic Safety Deposit Locker can be used only with a pin
number like a password.

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f) Safety:

⚫ Safety deals with the possible damage that can happen to the operating person
and environment due to the breakdown of an embedded system or due to the
emission of hazardous materials from the embedded products.

⚫ A safety analysis is a must in product engineering to evaluate the anticipated

damage and determine the best course of action to bring down the consequence
of damages to an acceptable level.

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NON -OPERATIONAL ATTRIBUTES

a) Testability and Debug-ability :

⚫ In hardware testing the peripherals and total hardware function in designed

manner
⚫ Firmware testing is functioning in expected way

⚫ Debug-ability is means of debugging the product as such for figuring out the
probable sources that create unexpected behavior in the total system .

b) Evolvability :
⚫ For embedded system, the qualitative attribute “Evolvability” refer to ease with
which the embedded product can be modified to take advantage of new
firmware or hardware technology.

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c) Portability :
⚫ Portability is measured of “system Independence”.
⚫ An embedded product can be called portable if it is capable of performing its
operation as it is intended to do in various environments irrespective of different
processor and or controller and embedded operating systems.

d) Time to prototype and market :

⚫ Time to Market is the time elapsed between the conceptualization of a product
and time at which the product is ready for selling or use

⚫ Product prototyping help in reducing time to market.

⚫ Prototyping is an informal kind of rapid product development in which

important feature of the under consider are develop.

⚫ In order to shorten the time to prototype, make use of all possible option like
use of reuse, off the shelf component etc.
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e) Per unit and total cost :
⚫ Cost is an important factor which needs to be carefully monitored. Proper
market study and cost benefit analysis should be carried out before taking
decision on the per unit cost of the embedded product.

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