What is embedded system?
An embedded system is some combination of
computer hardware and software, either fixed in
capability or programmable, that is designed for a
specific function or for specific functions within a
larger system. Industrial machines, agricultural
and process industry devices, automobiles,
medical equipment, cameras, household
appliances, airplanes, vending machines and toys
as well as mobile devices are all possible
locations for an embedded system.
An embedded system has three components :−
• It has hardware.
• It has application software.
• It has Real Time Operating system (RTOS)
• Easily Customizable
• Low power consumption
• Low cost
• Enhanced performance
• High development effort
• Larger time to market
Characteristics of an Embedded System
• Single-functioned :−
An embedded system usually performs
a specialized operation and does the same repeatedly.
• Reactive and Real time :−
Many embedded systems must
continually react to changes in the system's environment
and must compute certain results in real time without any
• Microprocessors based :−
It must be microprocessor or
• Memory :−
It must have a memory, as its software usually
embeds in ROM. It does not need any secondary memories
in the computer.
• Connected :−
It must have connected peripherals to connect
input and output devices.
• HW-SW systems :−
Software is used for more features and
flexibility. Hardware is used for performance and security.
Types of Embedded system:
Embedded system can be classified into different types
based on performance function requirement and
performance of the microcontroller.
Real time embedded system :
An embedded system that gives an output within a
specified amount of real time is
called real time embedded system. That is in
additional to a proper output it depends on
time constant as well.
Stand Alone embedded system:
These are embedded system that can work by
themselves. In other words they are self
sufficient and don't required a different system
to function. Music players, video gaming and
microwave ovens are the examples of standalon
• Network embedded system:
Embedded system that are connected to the network &
depends on it from their functionally are called network
embedded system. Router
home security system are network embedded system.
• Mobile embedded system
Embedded system that are mobile in nature are called
mobile embedded system. They include generally small
system. They are used in
portable embedded devices like cell phones, mobile, digital
camers, mp3 player and personal digital assistant.
Apllication of embedded system:
Here are some application area of embedded
• Consumer electronics:
Mobile phones , video games, printers, home
entertainment system, television, digital
camera, music player
• Household application:
Washing machine , diswashes, air conditioner,
• Medical equipment:
BLood pressure monitor, CET scanner, heart
beat monitor, ECG machine, etc
Anticlock breaking system, air conditionor control,
electronic fuel, injections, entertainment systems
• Industrial system
Robotic machine, control system, smoke detector, fire
detector, data collection system, system monitoring,
Navigation system, guided system, global positioning
Router, network hubs, phone, etc
Some Basic terms:
Most digital electronic circuits today are built with semi
conductor parts called chips. Chips are purchased from
manufacturers specializing in building such parts.
Semi-conductor themselves are enclosed in small thin
square or rectangle black package made of plastics or
ceramics. Each package made of plastics or ceramics.
Each package have collection of pins and those pins are
response for their own functions. Most digital circuit
use just two voltage to do their work
– OVDC somtimes called ground or low input.
– Either 3V or 5V sometimes called VCC or high
The most common mechanism to connect the chips to
one another is the printed circuit board.
A very simple part built from a handful of semiconductor transistor
is called gates or sometime discrete.
" A logic gate is an elementary building block of a digital circuit.
Most logic gates have two inputs and one output.
At any given moment , every terminal is in one of two binary
conditions low (0) or high(1)."
# Types of Gates:
An AND gate is one whose output is driven to high of both the
input are high and in other conditions the output is driven to low
A B Y
0 0 0
0 1 0
1 0 0
1 1 1
An OR gate is one which output is high if either or both of the
inputs are high. AND whose output is driven to low if only if both
input are low.
A B Y
0 0 0
0 1 1
1 0 1
1 1 1
NOT/ INVERTER gate:
Inverter are the very simple gate i.e output driven to low if the
input is high & vice- versa
The bubble or little loop on the invertor symbol is used in other schematic symbols to
indicate that an input or an output is inverted that is loop when it should be high &
AN XOR gate is one whose output is driven high if one if the input is high & other input
is low. And if both the input are high or low at that conditions the output is low, then it
is called XOR gate.
A B Y
0 0 0
0 1 1
1 0 1
1 1 1
NAND gate is not AND gate.
A B Y
0 0 1
0 1 1
1 0 1
1 1 0
It is one of the example of embedded system that
do the long-distance transmission of textual or symbolic (as
opposed to verbal or audio) messages without the physical
exchange of an object bearing the message. Telegraphy
requires that the method used for encoding the message
be known to both sender and receiver. Such methods are
designed according to the limits of the
signaling medium used.
– Telegraph must sort out on the network and provide the clean
data stream to the printer.
– Telegraph has to work with a number of different types of a
printers without customer configuration.
– Telegraph must respond quite rapidly to certain events.
– Telegraph must keep track of time
Cordless Bar-code scanner
A cordless barcode reader (or barcode scanner)
is an embedded system (electronic device) that
can read and output printed barcodes to
a computer. Like a flatbed scanner, it consists of a
light source, a lens and a light sensor translating
optical impulses into electrical ones. Additionally,
nearly all barcode readers
contain decoder circuitry analyzing the barcode's
image data provided by the sensor and sending
the barcode's content to the scanner's output
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