1. Embedded Systems: Implementation and Applications
Kaushik Padmanabhan
Department of Electronics and Communication Engineering
Velammal Engineering College, Chennai, TN
Abstract - An embedded system can be defined as the computing device that has computer hardware with software embedded in it
as one of its most important component. It may be either an independent system or a part of a larger system. As its software
usually embeds in ROM, it does not need secondary memories as in a computer. Nearly 99% of the processors manufactured end
up in embedded systems. Embedded systems find applications in every industrial segment. Embedded systems can be categorized
as stand-alone systems, real-time systems, networked information appliances & mobile devices. The embedded systems have
brought about radical changes in Electronics and Computer, they have also begun to impact other human activities. Embedded
systems are heterogeneous. Since they are mixtures of hardware and software, trade-off is important design decisions. But
embedded systems are more heterogeneous than just combining computer science & digital electronics. This paper presents an
overview of existing modes of Embedded Systems, architecture & their application. A look has also been given to future
deployment of Embedded Systems.
Keywords - Embedded Systems, Processors, Chips, Memory.
I. INTRODUCTION
Hardware & software that forms a component of some
larger system & is expected to function without human
intervention. Typically, an embedded system consists of a
single-board microcomputer with software in ROM, which
starts running a dedicated application as soon as power is
turned on & does not stop until power is turned off. An
embedded system is any device controlled by instructions
stored on a chip. These devices are usually controlled by a
microprocessor that executes the instructions stored on a
Read Only Memory (ROM) chip.
Fig. 1.0: CHIP
An embedded system is pre-programmed to perform a
dedicated or narrow range of functions as part of a larger
system, usually with minimal end-user or operator
intervention. The term 'embedded' implies that these chips
are an integral part of the system. Broadly speaking, these
programmable devices or systems are generally used to
perform, control or monitor processes, machinery,
environments, equipment and communications tasks. In fact
a general computer system is made up of numerous
embedded systems. If an embedded system is designed well,
the existence of the processor & the software could be
completely unnoticed by a user of the device.
II. CATEGORIES OF EMBEDDED SYSTEM
A. Stand-alone Embedded Systems
As the name implies, stand-alone systems work in stand-
alone mode. They take inputs, process them & produce the
desired output. The input can be electrical signal from
transducers or commands from a human being such as
pressing of a button. The output can be electrical signals to
drive another system, an LED or LCD display for displaying
of information to the users. Embedded Systems used in
process control, automobiles, consumer electronic items etc.
fall into this category in a process control system, the inputs
are from sensors that convert a physical entity such as
temperature or pressure into its equivalent electrical signal.
These electrical signals are processed by the system and the
appropriate electrical signals are produced.
B. Real-time Systems
Embedded Systems in which some specific work has to be
done in specific time period are called real-time systems.
For example- Consider a system that has to open a valve
within 30 milliseconds when the humidity crosses a
particular threshold. If the valve is not opened within 30
milliseconds, a catastrophe may occur. Such systems with
strict deadline are called hard real-time systems. On the
other hand, if we consider a DVD player and we give some
command from a remote control, & there is a delay of a
milliseconds in executing the command, but this delay

2. won’t lead to a serious implication. Such systems are called
as soft real-time systems.
C. Network Information Appliances
Embedded systems that are provided with network
interfaces & accessed by networks such as Local Area
Network or the Internet are called networked information
appliances. Such embedded systems are connected to a
network, typically a network running TCP/IP (Transmission
Control Protocol/Internet protocol) protocol suite, such as
the Internet or the Company’s Intranet.
A networked process control system consists of a number of
embedded systems connected as a LAN. Each embedded
system can send real-time data to a central location from
where entire process control system can be monitored. The
monitoring can be done using a web browser such as the
Internet Explorer. The door-lock of the home can be a
small-embedded system with TCP/IP and HTTP server
software running on it.
III. OVERVIEW OF EMBEDDED SYSTEM
ARCHITECTURE
Every embedded system consists of custom – built hardware
built around a Central Processing Unit (CPU). This
hardware also contains memory chips onto which software
is loaded. The software residing on the memory chip is
called the firmware. The embedded system architecture can
be represented as a layered architecture. The operating
system runs above the hardware and the application
software run above the operating system. It is not
compulsory to have an operating system in every embedded
system. For small appliances such as remote control units,
air conditioner, toys etc., there is no need for an operating
system. For applications involving complex processing, it is
advisable to have an operating system. In such a case, we
need to integrate the application software with the operating
system & then transfer entire software into a memory chip.
Once the software is transferred to the memory chip, the
software will continue to run for a long time & you don’t
need to reload the new software.
A. Building Block of hardware of an Embedded System
Central Processing Unit (CPU)
The CPU is a unit that centrally fetches & processes a set of
general-purpose instructions. The CPU instruction set
includes instructions for data transfer operations, ALU
operations, stack operations, input &output operations &
program control, sequencing & supervising operations. The
general-purpose instruction set is always specific to a
specific CPU.
Processor in the System
1. General Purpose Processor (GPP)
(a) Microprocessor
(b) Microcontroller
(c) Embedded Processor
(d) Digital Signals Processor (DSP)
(e) Media Processor
2. Application Specific System Processor (ASSP)
As Additional Processor
3. Multiprocessor system using General Purpose processors
(GPPS) & Application Specific Instruction Processors
(ASIPs)
4. GPP core(s) or ASIP core(s) integrated into either an
Application Specific Integrated Circuit (ASIC) or a Very
Large Scale Integrated Circuit (VLSI) circuit or an FPGA
core integrated with processor unit(s) in a VLSI (ASIC)
chip.
TABLE-I Block diagram of Component of the
Embedded System Hardware

3. Processor
A processor is the heart of the embedded system. For an
embedded system designer, knowledge of microprocessors
& Microcontrollers is a prerequisite. A processor has two
essential units:
 Program flow Control Unit (CU)
 Execution Unit (EU)
The CU includes a fetch unit for fetching instruction from
the memory. The EU has circuits that implement the
instructions pertaining to data transfer operation & data
conversion from one form to another. The EU includes the
Arithmetic and Logical Unit (ALU)
& also the circuits that execute instructions for a program
control tasks, say, halt, interrupt, or jump to another set of
instructions. It can also execute instructions for a call or
branch to another program & for a call to a function.
Processors runs the cycle of fetch & execute the instruction
defined in the processor instruction set are executing in the
sequence that they are fetched from the memory. A
processor is mostly in the form of an IC chip; alternatively,
it could be in core form in an ASIC or at a Soc. Core means
a part of the functional circuit on the VLSI chip.
Microprocessor
A microprocessor is a single VLSI chip that has a CPU and
may also have some other units (for Ex.: floating-point
processing arithmetic unit, pipelining &super-scaling units)
that are additionally present & that result in faster
processing of instructions.
Memory
The memory is categorized as Random Access
Memory (RAM) and Read Only Memory (ROM). The
contents of RAM will be erased if power is switched off.
So, the firmware is stored in the ROM. When the power is
switched on, the CPU reads the ROM, the program is
transferred to RAM and program is executed.
Input devices
Unlike the desktops, the I/P devices to an embedded
system have very limited capability. There will be keyboard
or a mouse, & hence interacting with the embedded system
is no easy task. Many embedded systems will have a small
keypad-you press one key to give a specific command. A
keypad may be used to I/P only the digits. Many embedded
system uses in process control do not have any I/P device
for user interaction; they take I/Ps from sensors or
transducers & produce electrical signals.
Output devices
The output devices of the embedded systems also
have very limited capability. Some embedded systems will
have a few Light Emitting Diodes to indicate the health
status of the system modules. A small Liquid Crystal
Display (LCD) may also be used to display some important
parameters.
IV. SPECIALITIES OF EMBEDDED SYSTEMS
While designing the embedded systems, developers have to
keep the below specialties in mind.
A. Performance
Many embedded systems have time constraints. For
instance, in a process control system, a constraint can be: “if
the temperature exceeds 40 degrees, open a valve within 10
milliseconds.” If the system meets such deadlines and they
are missed means, it may result in a catastrophe.
B. Power Consumption
Most of the embedded systems operate through a
battery. To reduce the battery drain & avoid frequent
recharging of the battery, the power consumption of an
embedded system has to be very low.
C. Cost
For an embedded system used in safety applications of a
nuclear plant or in a spacecraft, cost may not be a very
important factor. However, for an embedded system used in
consumer electronics or office automation, the cost is of
utmost importance.
D. Size
Size is certainly a factor for many embedded systems. For
instance, we do not like a mobile phone that has to be

4. carried on our backs. The size and the weight (i.e.
compactness) are the important parameters in embedded
systems that are used in aircraft, missiles etc.
E. Software Up gradation capability
Embedded systems are meant for a very specific task. So,
once the software is transferred to the embedded system, the
same software will run throughout its life. However, in
some cases, it may be necessary to upgrade the software.
V. RECENT TRENDS IN EMBEDDED SYSTEMS
In old good days, developing embedded systems was
confined to very specialists. Most of the embedded systems
are written only in assembly language & hence writing,
debugging & maintaining the code were very difficult &
time consuming. With the availability of powerful
processors & advanced development tools, embedded
software development is no longer ‘rocket science’.
A. Processor Power
The growing importance of embedded systems can be
gauged by the availability of processors about 150 varieties
of processors are available from around 50 semiconductor
vendors. Powerful 8-bit, 16- bit, 32-bit and 64-bit micro
controllers, & microprocessors are available to cater to the
different market segments the clock speed & memory
addressing capability of these processors are also increasing.
Very powerful digital signal processors are also available
for real time analyses of audio and video signals. As a
result, the power of desktop computers is now available on
palm tops.
B. Mobile Devices
Mobile devices such as mobile phones, Personal Digital
Assistants, smart phones etc. are a special category of an
embedded system. Though the PDA does many general-
purpose tasks, they need to be designed just like the
conventional embedded systems. The limitations of the
mobile devices-memory constraints, small size, display etc.
are same as those found in the embedded systems. Hence
mobile devices are considered as embedded systems.
C. Operating Systems
The advantage of embedded system in an operating system
is that the software development will be very fast &
marinating the code is very easy. The software can be
developed in a high level language such as “C”. So time to
market the system gets reduced. If real time performance is
required, a real time operating system can be used. In
addition, too many commercial embedded operating system
open source software campaigned let to development of
many open source operating system.
D. Communication Interfaces and Networking
Capability
With the availability of low-cost chips, embedded systems
can be provided networking capability through
communication interfaces such as Ethernet, 802.11b
wireless LAN & infrared. Network enabling of an
embedded system has many advantages: it can be accessed
over a network for remote control or monitoring.
E. Programming Languages
Development of embedded system was done mostly in
assembly languages. However, due to the availability of
cross-compilers, most of the development is now done in
high-level languages such as C and the object-oriented
languages like C++ & Java.
F. Development Tools
Availability of a number of tools for development,
debugging & testing as well as for modeling the embedded
systems is now paving way for the fast development of
robust & reliable systems. Development tools such as
BREW (Binary Routine Environment for wireless),
Wireless Application Protocol (WAP) development tools
facilitate easy development of applications for mobile
devices.
G. Programmable Hardware
PLDs& FPGA pave the way for reducing the components
on an embedded system, leading to small, low-cost systems.
After developing the prototype of an embedded system, for
mass production, FPGA can be developed by having all the
functionality of the processors, peripherals & application-
specific circuitry.
VI. APPLICATION AREAS
In today’s world the electronic devices have been
dominated. The children need embedded systems to play
smart video games. Housewives need embedded system for
smart Internet for compliant home appliances, such as,
microwave, television, music system, & so on.
Nearly 99%of the processors manufactured end up in
embedded systems. The embedded system market is one of
the highest growth areas as these systems are used in very
market segment- consumer electronics, office automation,
biomedical engineering, wireless communication, & data
communication, military and so on.
A. Consumer appliances
At home we use a number of embedded systems that include
digital camera, digital diary, DVD player, electronic toy,
microwave oven, remote controls for TV & air conditioner
etc. Today’s high-tech car has about 20 embedded systems

5. for transmission control, spark control, navigation etc. Even
wristwatches are now becoming embedded systems.
B. Industrial automation
Today a lot of industries use embedded systems for process
control. These include pharmaceutical, cement, sugar, oil
exploration, nuclear energy, electricity generation &
transmission. The embedded systems for industrial use are
designed to carry out the specific task such as monitoring
the temperature, pressure, humidity, voltage, current etc. &
then take appropriate action based on monitored levels to
control other devices.
C. Medical electronics
Almost every medical equipment in the hospital is an
embedded system. This equipment’s include diagnostic aids
such as ECG, EEG, blood pressure measuring devices & X-
ray scanners etc.
D. Computer Networking
Computer networking products such as bridges, routers,
Integrated Services Digital Networks (ISDN),
Asynchronous Transfer Mode & relay switches are the
embedded systems that implement the necessary data
communication protocols.
E. Wireless technologies
Advances in mobile communications are paving way for
many interesting applications using embedded systems. The
mobile phone is one of the marvels of the last decade of the
20th century. It is very powerful embedded system that
provides voice communication while we are on the move.
F. Instrumentation
Testing & measurement are the fundamental requirements in
all scientific and engineering activities. The measuring
equipment we use in laboratories to measure parameters
such as weight, temperature, voltage, current etc. are all
embedded systems. Test equipment such as oscilloscope,
logic analyzer, protocol analyzer, radio communication test
set etc, are embedded systems built around powerful
processors.
G. Security
Security of persons and information has always been a
major issue. We need to project our homes and offices, &
also the information we transmit & store. Developing
embedded systems for security applications is one of the
most lucrative businesses nowadays.
H. Finance
Financial dealing through cash & cheques are now slowly
paving way for transactions using smart cards and ATM
(Automatic Teller Machine, also expanded as Any Time
Money) machine. Smart card, of the size of a credit card,
has a small micro-controller and memory and it interacts
with the smart card reader / ATM machine & acts as an
electronic wallet.
VII. SPECIFIC APPLICATIONS
A. Automated teller machine (ATM)
ATM is an electronic device that allows a bank's customers
to make cash withdrawals and check their account balances
without the need for a human teller. Many ATMs also allow
people to deposit cash or cheques, transfer money between
their bank accounts or even buy postage stamps. There are
ATMs that are accessible to blind and visually impaired
peoples. This is one of the great inventions. These are types
of ATMs whose keypads are equipped with Braille system.
B. Embedded system in a shoe
The microprocessor embedded in this Adidas
running shoe calculates the pressure between the runner's
foot & the ground five million times per second &
continuously changes the cushioning to match an adjustable
comfort level. The computer controls a motor that lengthens
& shortens a cable attached to a plastic cushioning element.

6. VIII. CONCLUSION
An embedded system is closely integrated with the main
system. It may not interact directly with the environment.
Thus embedded systems contain programmed instruction
running via processor chips. They perform control,
protection & monitoring tasks. In broad terms embedded
systems are programmable devices or systems which are
generally used to control or monitor things like processes
machinery, environmental equipment & communications.
The range of embedded system is vast & includes all
industrial & commercial sectors. Embedded systems are
rapidly becoming a catalyst for change in the computing,
data communication, telecommunications, industrial control
& entertainment sector. The objective of this study is to
enlighten readers about the application of embedded
systems; the embedded systems technology and the impact
of the technology on various markets.
XI. REFERENCES
i) Embedded Systems Architecture, Designing and
Programming – By Rajkamal.
ii) Embedded Systems Programming and Designing –
By Michael Barr.
iii) Designing Of Embedded Hardware – By John
Keysoukisi.
iv) Embedded System Design – By Frank Vahid.
v) www.nptel.iitm.ac.in, www.embedded.com