The document provides an introduction to embedded systems including definitions, explanations and comparisons to general purpose computer systems. It discusses the core components of embedded systems including hardware components like processors, memory and I/O as well as software components like operating systems and device drivers. It also covers various embedded system classifications, applications and communication interfaces.

1. Unit – I
Introduction to Embedded System
• Definition – “Embedded systems are
computing systems with tightly coupled
hardware and software integration, which are
designed to perform a dedicated function”.
• Explanation – An embedded system is a
combination of computer hardware along
with the mechanical or electrical parts, and
system software to perform some specific
task.

2. Embedded system and General
purpose computer system
• An embedded system refers to “A computer
which has been designed to do specialized
tasks. Example – Vending machine machine or
printer etc.
• General purpose computer system is a
combination of hardware and software which
performs different task by following the
instruction provided by the user .It is not
designed to solve any particular problem.

3. Difference b/w E.S and G.P.Computer
E.S
system
• An embedded system is designed to perform some special
task.
• It uses simplified circuit.
• Less memory is required.
• It uses slow processor.
• It is low in cost.
General Purpose computer system
• It is designed to perform a variety of task.
• The circuit is more complex.
• It requires more memory.
• It requires high speed processor.
• It is high in cost

4. Classification of Embedded System
Classification of E.S
Classification based on
Classification based on the
Hardware and
Function
software Complexity
Netw
Standalon ork Mobile Mediu
Real Sophis
e Appli Embedded Small m
Time ticated
embedded catio System Scale E.S scale
E.S E.S
system n E.S

5. Classification based on the Function
• Standalone E.S – It is built using a specialized
communication processor, memory a number
of network access interfaces and special
software that implements logic for sending
information from one device to another
decice.
• Real Time E.S – It monitors the

6. Purpose of E.S
• E.S are small, fast and very powerful tools.
• An E.S is a micro-processor based system that is built to
control a function or range of functions .
• E.S is designed to perform one or a few dedicated or
specific functions but with choices and different options.
• E.S are often required to provide Real-Time response.
• A Real-Time is defined as a system whose correctness
depends on the timeliness of its response. Example –
flight control system of an aircraft, sensor system in
nuclear reactors and power plants.

7. Why do we need E.S
• General purpose computers like PC’s would be too costly
for the majority of products that incorporate some form of
E.S technology.
• General purpose computers might fail to meet a number of
functional or performance requirements such as
constraints in power-consumption, size limitation etc.
• In todays digital world the life totally depends on at least
one piece of equipment which contains processor like a
phone, television, washing machine etc.
• The power requirement of E.S like cell phone , cameras are
very less as compared to the other general purpose
computer system.

8. Application of E.S
Some applications of E.S are as follows:
Automobile Sector:
E.S is widely used in automobile industries not only in the
development of automobiles but also in vehicles for achieving various
automated operations.
Automobile sector uses the embedded system in the following:
Anti-lock braking system(ABS)
Electronic Stability Control (ESC/ESP)
Traction Control (TCS)
Automatic Four-Wheel Drive
Fuel Injecton Control
Air bags and Automatic braking
Car Entertainment systems

9. • Telecommunication- This industry utilizes
numerous embedded systems from telephone
switches for the network to mobile phones at the
enduser.
• Telecom industry uses the E.S in the following:
 In Telephone lines to route data
 For messaging
 For other multimedia features in cell phones
and other devices.
 In network router and bridges
 Rocket and satellite control.
 Air Traffic Control.

10. • Aerospace and Avionics – E.S is more popular in this
field because a complex mixture of hardware,
electronics and embedded software is required to fulfill
the requirements.
• Embedded engineers confront major challenges in this
field like:
• Specially designed programs that helps to synchronize
the hardware of aero vehicles and the system software
of ATC, to take-off and landing the aero-vehicles.
• Ensuring that the complex software and hardware
interactions are right.
• Assembling components that meet specifications and
perform effectively together.
• Understanding the larger context of the embedded
software.

11. • Consumer Electronics: This field has benefited
a lot from embedded technologies like:
• MP3 Players
• Mobile Phones
• Digital Cameras
• Printers
Defense: The defense field also uses the E.S
services in RADARs, Guided Missile Systems,
automated guns and satellite phones.

12. Core Components of E.S

13. Hardware
Processor – or the CPU is responsible for performing all
the computational and logical operations in an E.S.
Memory – It is odevice which can be used to store data in
a system. An E.S can have on-chip or off –chip memory.
There are different kinds of memory devices.
User Interface – It is a mechanism through which user can
provide certain choices to the E.S. These choices are
used by the CPU to perform a given task in certain
manner. Keypad is one of the most common UI.

14. Displays – These are used to provide certain
information to the user. Alphanumeric Displays
and LCD displays are widely used in embedded
device.
Input/Output: I/O peripherals provide a physical
media for Data Transfer with the external world.
Other Electrical Components: There are plenty
of other active and passive components in an
E.S. Examples Power supply, Data Converters
etc.

15. Software
• Control software:- It is responsible for
managing different modules of the system.
• Computation Extensive software: - It is
responsible for performing mathematical and
logical operations on the input data. The
output of this can be sent back or stored for
later use or can be used by the control
software to take certain decisions.

16. • Device Drivers: - These are the software
modules which control system’s peripheral.
• User Interface:- This software is responsible
for collecting user inputs and providing “User
Menu” or “System Status” to the user.
• Operating system : It is a software which
manages the different resources of a system
and provides an abstraction of the underlying
hardware to the users.

17. Microprocessors and Microcontrollers
• Microprocessors – It is a programmable integrated
circuit that can perform any type of arithmetic or
logical operation within a fraction of second.
• It forms a vital role on a computer system.
• Microprocessor is a high speed computer with less
storage capacity within it.
• It is also called as CPU or Central Processing Unit.
• It is the heart of a computer.
• It is a complete computation engine that is fabricated
on a single chip.
• The first miroprocessor was developed by intel

18. Working of Microprocessor
• A microprocessor executes a collection of
machine instructions that tell the processor what
task to do.
• A microprocessor does three basic things:-
 Using ALU it can perform mathematical
operations like addition, subtraction,
multiplication and division.
 It can move data from one memory location to
another.
 It can make decisions and jump to a new set of
instructions based on those decisions.

19. Microcontroller
• It is a small computer on a single integrated
circuit containing a processor core, memory and
programmable input/output peripherals.
• It is designed for personal computers or other
general purpose applications.
• They are used in automatically controlled
products and devices like automobile engine
control systems, applications etc.
• Microcontrollers are special purpose computer.

20. • Microcontrollers are embedded inside some
other device so that they can control the
features or actions of the product.It is also
called as “embedded controller”.
• They are dedicated to do one task and run one
specific program. The programs are stored in
ROM.
• They are low power devices ie they consume
less power.
• It has a dedicated input device and often has a
small LED or LCD display for output.
• It is often small and low cost.

21. Difference b/w Microprocessor and
Microcontroller
Microprocessor –
 It is a general purpose device that finds its applications in
most of the electronic device.
 It is a dependant unit that requires other chips for its proper
operation.
 It is called as a IC which contains many useful functions.
 It requires external memory devices to stored set of
instructions to carry out user defined tasks.
 It main use is to read data, perform extensinve calculations on
that data, and store the results in a mass storage device or
display the results.
 Example for microprocessor is 8085.
 It uses the memory chips to get the data.

22. • Microcontroller.
 It is a specific purpose device which has a specific
task for a sepecfic device.
 It is an independent device that does not require any
other specific chips.
 It is called as Microchip which contains the
components of microprocessor.
 It has the ability to execute a stored set of
instructions to carry out user defined tasks.
 It is used to control the operations of a machine
using a fixed program that is stored in Rom and does
not change over the lifetime of the system.
 Example of microcontroller is 8051.

23. RISC AND CISC Controllers
• RISC – Reduced Instruction Set Computing
It is designed to perform a smaller number of
types of computer instructions so that it can
operate at a higher speed.
The range of instructions is 30 to 40.
It is a type of microprocessor architecture that
utilizes a small, highly-optimezed set of
instructions , rather than a more specialized set
of instructions often found in other types of
architectures.

24. • CISC- Complex Instruction Set Computing
Here a single instruction can execute several
low-level operations and is capable of
performing multi-step operations or
addressing modes within single instructions.
Pentium microprocessors are CISC
microprocessors.

25. Difference b/w RISC and CISC
• RISC –
 It has lesser number of instructions.
 It uses High level instructions.
 Provides instruction pipelining.
 Increased execution speed.
 Single fixed length instruction.
 Less silicon and pins are used.
 Design time is reduced.
 It uses Harvard Architecture.
 Large number of registers are available.

26. • CISC
It has more number of instructions.
It rarely uses high-level instructions.
Instruction pipelining is not used.
Comparative lesser speed.
Variable length instructions.
More silicon and pins are used.
Increased design time.
Uses Von Neumann Architecture.
Limited number of general purpose registers
available.

27. Big Endian and Little Endian Processors
• Big Endian and Little Endian processors
describe the order in which a sequence of
bytes are stored in computer memory.
Big Endian is an order in which the most
significant value in the sequence is stored first at
the lowest storage address.
Little Endian is an order in which the least
significant value in the sequence is stored first.

28. Application Specific Integrated
Circuits(ASIC)
• It is designed to perform some specific function
or task.
• It is a microchip customized for a particular use
rather than for general purpose use.
• Ex- A chip designed solely to run a cell phone is
an ASIC.
• It include entire 32-bit processors , memory
blocks including ROM, RAM, EEPROM, Flash and
other large building blocks.
• ASIC is often termed as SoC (System-on-a-Chip).

29. ASCIsTypes
• ASCIs are categorized according to the technology used for
manufacturing them. They are:
• Full-custom- The full custom IC’S are the ASIC that cannot be
modified to suit for the different applications.
• These are entirely tailor-fitted to a particular application from
the very start.
• As its design and functionality is pre-specified by the user it is
manufactured with all the layers fully defined like off-the-shelf
general purpose IC’S.
• Semi-custom – These ASCI can be modifies partially.
• Semi-custom ASIC’S can be partly customized to serve
different functions within its general area of application.
• Semi-custom ASIC’S are designed to allow a certain degree of

30. • Structured or Platform ASIC –
• This belongs to a relatively new ASIC
classification.
• These are designed and produced from a
tightly defined set of design methodologies
,intellectual properties and well-characterized
silion.
• This type of ASIC is developed for shortening
the design cycle and minimizing the
development costs of the ASIC.

31. Programmable Logic Devices(PLD)
• It is an electronic component used to build
reconfigurable digital circuits.
• A PLD has an undefined function at the time
of manufacture.
• Before the PLD can be used in a circuit it must
be programmed that is reconfigured.

32. Classification of PLD
Classification of
Devices
Fixed Logic Programmable
Devices Logic Devices
FLD PLD

33. FLD
• The circuits in a FLD are permanent.
• They are made to perform one function or set
of functions.
• Once FLD’S are manufactured they cannot be
changed.
• With FLD’s the time required to go from
design, to prototypes, to a final manufacturing
run can take from several months to a year.

34. PLD

35. Sensors
• Sensors are also called as detectors.
• The changes in the system environment or variables are
detected by the sensors connected to the input port of the
embedded system.
• It is a transtrucer that converts energy from one type to
another type for any particular purpose.
• Example- ECG machine it is designed to monitor the heart
beat status of a patient and it canot impose a control over
the patient’s heart beat and its order. The sensors are used
here are the different electrode sets connected to the body
of the patient.
• The variations are captured and presented to the user
through a visual display or some printed chart.

36. Actuators
• Actuator is a form of transducer device which converts
signals to corresponding physical action.
• Actuator acts as an output device.
• If the embedded system is designed for any controlling
purpose the system will produce some changes in the
controlling variable to bring the controlled variable to
the desired value. This is achieved through an actuator
connected to the output port of the embedded system.
• If the E.S is designed for monitoring purpose only then
there is no need for including an actuator in the
system.

37. Types of Actuators
Classification of Actuators
Multi-Turn Actuator Part-Turn Actuator Linear Actuator

38. Multi-turn Actuator-
• It is an actuator which transmits to the valve a
torque for at least one full revolution. It is
capable of withstanding thrust.
• It is required for the automation of multi-turn
valves.
• One of the main type of this is the gate valve.

39. Part-turn actuators –
• It is an actuator which transmits a torque to the
valve for less than one full revolution. It is not
capable of withstanding thrust.
• The major representatives of this type are
butterfly valves and ball valves.
Linear Actuator –
• The major representative of this type are the
control valves.
• Just like the plug in the bathtub is pressed into
the drain the plug is pressed into the plug seat by
a stroke.

40. Communication Interface
• These are the devices through with the E.S can
interact with various subsystems and the
external world.
• For embedded product communication interface
can be viewed in two different perspectives :
1)Device/board level communication interface(On
board communication Interface)
2)Product level communication interface (External
communication interface)

41. Onboard communication Interface
• The communication channel which
interconnects the various components within
an embedded product is referred as
device/broad level communication interface.
• Examples – Serial interfaces like I2C,I-Wire,
and parallel bus interface.

42. External Communication interface
• These are the E.S which may be a part of large
distributed system and they require interaction and
data transfer between various devices and sub-
modules.
• The product level communication interface is
responsible for data transfer between the E.S and other
devices or modules.
• The external communication interface can be either a
wired media or a wireless media and it can be a serial
or a parallel interface.
• Examples – Infrared (IR), Bluetooth(BT), Wireless LAN
(Wi-Fi),Radio Frequency waves etc.

43. On Board Communication Interface
Inter Integrated Circuit Bus (I2C Bus) –
• It is a synchronous bi-directional half duplex two
–wire serial bus which provides communication
link between integrated circuits.
• It was designed by Philips Semiconductors in
1980s.
• It was developed to provide an easy way of
connection between a microprocessor /
microcontroller system and peripheral chips in
television sets.

44. • It comprises of two bus lines i.e Serial Clock-SCL and Serial
Data-SDA.
• SCL line is responsible for generating synchronisation clock
pulses.
• SDA is responsible for transmitting the serial data across
devices.
• I2C bus is a shared bus system to which many number of
I2C devices can be connected.
• Devices connected to the I2C nus can act as either
“Master” device or “Slave” device.
• The Master device is responsible for controlling the
communication by initiating or terminating data transfer,
sending data and generating necessary synchronisation
clock pulses.
• The Slave devices wait for the commands from the Master
and respond upon receiving the commands.

45. • Master and Slave devices can act as either
transmitter or receiver.
• Regardless whether a master is acting as
transmitter or receiver the synchronisation
clock signal is generated by Master device
only.
• I2C supports multi masters on the same bus.

46. External Communication Interfaces
• Infrared –
Infrared is a serial ,half duplex, line of sight based wireless technology
for data communication between devices.
The remote control of TV, AC works on the infrared data
communication principle.
IR uses infrared waves of the electromagnetic spectrum for
transmitting the data.
It supports point-point and point-to-multipoint communication.
The typical communication range for IR lies in the range of 10 cm to
1m.
The range can be increased by increasing the tranmitting power of the
IR device.
IR supports data rates ranging from 9600bits/sec to 16Mbps.

47. Embedded Firmware

48. UNIT –II
Characteristics and Quality Attributes of E.S
Embedded systems possess certain specific
characteristics and these are unique to each
embedded system.
1. Application and domain specific
2. Reactive and Real Time
3. Operates in harsh environments
4. Distributed
5. Small Size and weight
6. Power concerns

49. Application and Domain Specific –
• Each E.S has certain functions to perform and
they are developed in such a manner to do
the intended functions only.
• They cannot be used for any other purpose.
• Ex – The embedded control units of the
microwave oven cannot be replaced with AC’S
embedded control unit because the
embedded control units of microwave oven
and AC are specifically designed to perform
certain specific tasks.

50. Reactive and Real Time –
• E.S are in constant interaction with the real world through
sensors and user-defined input devices which are
connected to the input port of the system.
• Any changes in the real world care captured by the sensors
or input devices in real time and the control algorithm
running inside the unit reacts in a designed manner to
bring the controlled output variables to the desired level.
• E.S produce changes in output in response to the changes
in the input, so they are referred as reactive systems.
• Real Time system operation means the timing behaviour of
the system should be deterministic ie the system should
respond to requests in a known amount of time.
• Example – E.S which are mission critical like flight control
systems, Antilock Brake Systems (ABS) etc are Real Time
systems.

51. Operates in Harsh Environment –
• The design of E.S should take care of the
operating conditions of the area awhere the
system is going to implement.
• Ex – If the system needs to be deployed in a
high temperature zone, then all the
components used in the system should be of
high temperature grade.
• Also proper shock absorption techniques
should be provided to systems which are
going to be commissioned in places subject to
high shock.

52. Distributed –
• It means that embedded systems may be a
part of a larger system.
• Many numbers of such distributed embedded
systems form a single large embedded control
unit.
• Ex – Automatic vending machine. It contains a
card reader , a vending unit etc. Each of them
are independent embedded units but they
work together to perform the overall vending
function.

53. Small Size and Weight –
• Product aesthetics(size,weight,shape,style,etc)
is an important factor in choosing a product.
• It is convenient to handle a compact device
than a bulky product.
• In embedded domain compactness is a
significant deciding factor.

54. Power Concerns –
• Power management is another important
factor that needs to be considered in
designing embedded systems.
• E.S should be designed in such a way as to
minimize the heat dissipation by the system.

55. Quality Attributes of Embedded
System
Quality attributes are the non-functional
requirements that need to be documented properly
in any system design.
Quality attributes can be classified as Operational
quality attributes and non-operational quality
attributes.

56. Quality Attributes of E.S
Operation Q.A Non-Operational Q.A
Response Testability and Debug-ability
Throughput Evolvability
Reliability Portability
Maintainability Time to Prototype and Market
Security
Per Unit and Total Cost
Safety

57. Operational Quality Attributes
• The operational quality attributes represent the relevant
quality attributes related to the embedded system when it
is in the operational mode or online mode.
Operational Q.A are:
Response –
It is the measure of quickness of the system.
It tells how fast the system is tracking the changes in input
variables.
Most of the E.S demand fast response which should be almost
real time.
Ex – Flight control application.

58. Throughput –
• It deals with the efficiency of a system.
• It can be defined as the rate of production or
operation of a defined process over a stated
period of time.
• Ex – In case of card reader throughput means
how many transactions the reader can
perform in a minute or in an hour or in a day.
• Throughput is generally measured in terms of
“Benchmark”.
• A Benchmark is a reference point by which
something can be measured.

59. Reliability –
• It is a measure of how much we can rely upon
the proper functioning of the system.
• Mean Time Between Failure (MTBF) and Mean
Time To Repair (MTTR) are the terms used in
determining system 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 a failure.
• For embedded system with critical application
need, it should be of the order of minutes.

60. Maintainability –
• It deals with support and maintenance to the
end user or client in case of technical issues
and product failure or on the basis of a
routine system checkup.
• Reliability and maintainability are
complementary to each other.
• A more reliable system means a system with
less corrective maintainability requirements
and vice versa.
• As the reliability of the system of the system
increases the chances of failure and non-
functioning also reduces thereby the need for
maintainability is also reduced.

61. Security –
• Confidentiality, Integrity and availability are
the three major measures of information
security.
• Confidentiality deals with protection of data
and application from unauthorized disclosure.
• Integrity deals with the protection of data and
application from unauthorized modification.
• Availability deals with protection of data and
application from unauthorized users.

62. Safety –
Safety deals with the possible damages that can
happen to the operator, pubic and the
environment due to the breakdown of an E.S .
The breakdown of an embedded system may
occur due to a hardware failure or a firmware
failure.
Safety analysis is a must in product engineering
to evaluate the anticipated damages and
determine the best course of action to bring
down the consequences of the damages to an
acceptable level.

63. Non-Operational Quality Attributes
The quality attributes that needs to be addressed for the
product not on the basis of operational aspects are
grouped under this category.
Testability and Debug-ability –
• Testability deals with how easily one can test the
design, application and by which means it can be done.
• For an E.S testability is applicable to both the
embedded hardware and firmware.
• Embedded hardware testing ensures that the
peripherals and total hardware functions in the desired
manner, whereas firmware testing ensures that the
firmware is functioning in the expected way.

64. Evolvability –
• It is a term which is closely related to Biology.
• It is referred as the non-heritable variation.
• For an embedded system evolvability refers to
the ease with which the embedded product can
be modified to take advantage of new firmware
or hardware technology.
Portability-
• It is the measure of system independence.
• An embedded product is said to be portable if the
product is capable of functioning in various
environments, target processors and embedded
operating systems.

65. Time-to-Prototype and Market –
It is the time elapsed between the
conceptualisation of a product and the time at
which the product is ready for selling.
Per Unit Cost and Revenue –
• Cost is a factor which is closely monitored by
both end user and product manufacturer.
• Any failure to position the cost of a
commercial product at a nominal rate may
lead to the failure of the product in the
market.