1.Embedded Systems(6)

8/9/2019 1.Embedded Systems(6)

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EMBEDDED SYSTEM ARCHITECTURE AND

APPLICATIONS

1. EMBEDDED SYSTEMS

An embedded system can be defined as a computing device that does a specific focused

job. Appliances such as the air-conditioner, VCD player, DVD player, printer, fax machine,

mobile phone etc. are examples of embedded systems. Each of these appliances ill have a

processor and special hardare to meet the specific re!uirement of the application along ith the

embedded softare that is executed by the processor for meeting that specific re!uirement. "he

embedded softare is also called #firm are$. "he des%top&laptop computer is a general purpose

computer. 'ou can use it for a variety of applications such as playing games, word processing,

accounting, softare development and so on. (n contrast, the softare in the embedded systems

is alays fixed listed belo)

Embedded systems do a very specific tas%, they cannot be programmed to do different

things. . Embedded systems have very limited resources, particularly the memory. *enerally,

they do not have secondary storage devices such as the CD+ or the floppy dis%. Embedded

systems have to or% against some deadlines. A specific job has to be completed ithin a

specific time. (n some embedded systems, called real-time systems, the deadlines are stringent.

issing a deadline may cause a catastrophe-loss of life or damage to property. Embedded

systems are constrained for poer. As many embedded systems operate through a battery, the

poer consumption has to be very lo.

ome embedded systems have to operate in extreme environmental conditions such as

very high temperatures and humidity.

1.1 EMBEDDED SYSTEM ARCHITECTURE


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/et us see the details of the various building bloc%s of the hardare of an embedded

system. As shon in 0ig 1.2.2 the building bloc%s are3

• Central 4rocessing 5nit 6C457

• emory 6+ead-only emory and +andom Access emory7

• (nput Devices

• utput devices

• Communication interfaces

Application-specific circuitry

Fig 2.2.1 Block Diagram of Hardware of Emedded S!"#em

1.1.1Ce$#ral %roce""i$g U$i# &C%U'(


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"he Central 4rocessing 5nit 6processor, in short7 can be any of the folloing)

microcontroller, microprocessor or Digital ignal 4rocessor 6D47. A micro-controller is a lo-

cost processor. (ts main attraction is that on the chip itself, there ill be many other components

such as memory, serial communication interface, analog-to digital converter etc.

o, for small applications, a micro-controller is the best choice as the number of external

components re!uired ill be very less. n the other hand, microprocessors are more poerful,

but you need to use many external components ith them. D84 is used mainly for applications in

hich signal processing is involved such as audio and video processing.

1.1.2 Memor!(

"he memory is categori9ed as +andom Access 11emory 6+A7 and +ead nly emory

6+7. "he contents of the +A ill be erased if poer is sitched off to the chip, hereas

+ retains the contents even if the poer is sitched off. o, the firmare is stored in the

+. :hen poer is sitched on, the processor reads the +3 the program is program is

executed.

1.1.) I$*+# De,ice")

5nli%e the des%tops, the input devices to an embedded system have very limited

capability. "here ill be no %eyboard or a mouse, and hence interacting ith the embedded

system is no easy tas%. any embedded systems ill have a small %eypad-you press one %ey to

give a specific command. A %eypad may be used to input only the digits. any embedded

systems used in process control do not have any input device for user interaction3 they ta%e

inputs from sensors or transducers produce electrical signals that are in turn fed to other systems.

1.1.- +#*+# de,ice")

"he output devices of the embedded systems also have very limited capability. ome

embedded systems ill have a fe /ight Emitting Diodes 6/EDs7 to indicate the health status of


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the system modules, or for visual indication of alarms. A small /i!uid Crystal Display 6/CD7

may also be used to display some important parameters.

1.1./ Comm+$ica#io$ i$#erface"(

"he embedded systems may need to, interact ith other embedded systems at they may

have to transmit data to a des%top. "o facilitate this, the embedded systems are provided ith one

or a fe communication interfaces such as +2;2, +7,

and (EEE 1;?


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1.2.2 ffice A+#oma#io$(

"he office automation products using embedded systems are copying machine, fax

machine, %ey telephone, modem, printer, scanner etc.

1.2.) I$d+"#rial A+#oma#io$)

"oday a lot of industries use embedded systems for process control. "hese include

pharmaceutical, cement, sugar, oil exploration, nuclear energy, electricity generation and

transmission. "he embedded systems for industrial use are designed to carry out specific tas%s

such as monitoring the temperature, pressure, humidity, voltage, current etc., and then ta%e

appropriate action based on the monitored levels to control other devices or to send information

to a centrali9ed monitoring station.

1.2.- Medical Elec#ro$ic")

Almost every medical e!uipment in the hospital is an embedded system. "hese

e!uipments include diagnostic aids such as EC*, EE*, blood pressure measuring devices, B-ray

scanners3 e!uipment used in blood analysis, radiation, colonoscopy, endoscope etc.

Developments in medical electronics have paved ay for more accurate diagnosis of diseases.

1.2./ Com*+#er 3e#worki$g)

Computer netor%ing products such as bridges, routers, (ntegrated ervices Digital

etor%s 6(D7, Asynchronous "ransfer ode 6A"7, B.28 and frame relay sitches are

embedded systems hich implement the necessary data communication protocols. 0or example,

a router interconnects to netor%s. "he to netor%s may be running different protocol stac%s.

1.2.0 Telecomm+$ica#io$")

(n the field of telecommunications, the embedded systems can be categori9ed as

subscriber terminals and netor% e!uipment. "he subscriber terminals such as %ey telephones,

(D phones, terminal adapters, eb cameras are embedded systems. "he netor% e!uipment

includes multiplexers, multiple access systems, 4ac%et Assemblers Dissemblers 64ADs7,


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sate11ite modems etc. (4 phone, (4 gateay, (4 gate%eeper etc. are the latest embedded systems

that provide very lo-cost voice communication over the (nternet.

1.2.4 5irele"" Tec6$ologie")

Advances in mobile communications are paving ay for many interesting applications

using embedded systems. "he mobile phone is one of the marvels of the last decade of the 2@h

century. (t is a very poerful embedded system that provides voice communication hile e are

on the move. "he 4ersonal Digital Assistants and the palmtops can no be used to access

multimedia services over the (nternet. obile communication infrastructure such as base station

controllers, mobile sitching centers are also poerful embedded systems.

1.2.7 Sec+ri#!(

ecurity of persons and information has alays been a major issue. :e need to protect

our homes and offices3 and also the information e transmit and store. Developing embedded

systems for security applications is one of the most lucrative businesses noadays. ecurity

devices at homes, offices, airports etc. for authentication and verification are embedded systems.

1.Embedded Systems(6)

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