Report on Wireless Robot

8/6/2019 Report on Wireless Robot

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ACERC/DOECE/2010-11/MAJPRJ/1

Chapter 1

INTRODUCTION TO ROBOTICS

1.1 History

y Leonardo da Vinci created many robot-like sketches and designs in the 1500s.y The word robot first appeared in print in the 1920 play R.U.R. (Rossums Universal

Robots) by Karl Kapek, a Czechoslovakian playwright. Robota is Czechoslovakian for

worker or serf (peasant). Typical of early science fiction, the robots take over and

exterminate the human race.

y Isaac Asimov popularized the term robotics through many science-fiction novels andshort stories. Asimov is a visionary who envisioned in the 1930s the positronic brain for

controlling robots; this pre-dated digital computers by a couple of decades. Unlike earlier

robots in science fiction, robots do not threaten humans since Asimov invented the three

laws of robotics:1. A robot may not harm a human or, through inaction, allow a human to come to harm.

2. A robot must obey the orders given by human beings, except when such orders conflict

with the First Law.

3. A robot must protect its own existence as long as it does not conflict with the First or

Second Laws.

1.2 Introduction

Word robot was coined by CZECH novelist Karel Capek in 1920 play titled Rassums

Universal Robot (RUR). Robot in CZECH is a word for worker or servant.

For many people it is a machine that imitates a human like the androids in star wars,

terminator and star trek: the next generation. However these robots capture our imagination, such


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robots still only inhabit science fiction. People still have not been able to give a robot enough

common sense to reliably interact with a dynamic world. However lots of scientists are

working over this project to make the world of robot more and more advance.

The types of robots that we encounter most frequently are robots that do work that are too

dangerous, boring, onerous, or just plain nasty. Most of the robots in the world are of this type.

They can be found in auto, medical, manufacturing and space industries. In fact, there are over

millions of these type type of robots working for us today.

Some robots like the mars rover sojourner and upcoming mars exploration rover, or the under

water robot caribou help us learn about places that are too dangerous for us to go. While other

types of robots are just plain fun for kids of all ages. Popular toys such as teckno, polly or AIBO

ERS-220 seems to hit the stores shelves every year around festive time.

And as much fun as robots are to play with, robots are even much more fun to build. In Being

Digital, Nicholas Negroponte tells a wonderful story about an eight year old, pressed during a

televised premier of MITMedia Lab's LEGO/Logo work at Hennigan School. A zealous anchor,

looking for a cute sound bite, kept asking the child if he was having fun playing with

LEGO/Logo. Clearly exasperated, but not wishing to offend, the child first tried to put her off.

After her third attempt to get him to talk about fun, the child, sweating under the hot television

lights, plaintively looked into the camera and answered, "Yes it is fun, but it's hard fun."

But what exactly is a robot?

As strange as it might seem, there really is no standard definition for a robot. However,

there are some essential characteristics that a robot must have and this might help you to decide

what is and what is not a robot. It will also help you to decide what features you will need to

build into a machine before it can count as a robot.

A robot has these essential characteristics:

y Sensing First of all your robot would have to be able to sense its surroundings. It woulddo this in ways that are not unsimilar to the way that you sense your surroundings. Giving

your robot sensors: light sensors (eyes), touch and pressure sensors (hands), chemical


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sensors (nose), hearing and sonar sensors (ears), andtaste sensors (tongue) will give your

robot awareness of its environment.

y Movement A robot needs to be able to move around its environment. Whether rolling onwheels, walking on legs or propelling by thrusters a robot needs to be able to move. To

count as a robot either the whole robot moves, like the Sojourner or just parts of the robot

moves, like the Canada Arm.

y Energy A robot needs to be able to power itself. A robot might be solar powered,electrically powered, battery powered. The way your robot gets its energy will depend on

what your robot needs to do.

Intelligence A robot needs some kind of "smarts." This is where programming enters the

pictures. A programmer is the person who gives the robot its 'smarts.' The robot will have to havesome way to receive the program so that it knows what it is to do

Well it is a system that contains sensors, control systems, manipulators, power supplies

and software all working together to perform a task. Designing, building, programming and

testing a robots is a combination of physics, mechanical engineering, electrical engineering,

structural engineering, mathematics and computing. In some cases biology, medicine, chemistry

might also be involved. A study of robotics means that students are actively engaged with all of

these disciplines in a deeply problem-posing problem-solving environment.

1.3 Technical Robotics Terms

Speed

Speed is the amount of distance per unit time at which the robot can move, usually

specified in inches per second or meters per second. The speed is usually specified at a specific

load or assuming that the robot is carrying a fixed weight. Actual speed may vary depending

upon the weight carried by the robot.

Load Bearing Capacity

Load bearing capacity is the maximum weight-carrying capacity of the robot. Robots that

carry large weights, but must still be precise are expensive.


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Accuracy

Accuracy is the ability of a robot to go to the specified position without making a

mistake. It is impossible to position a machine exactly. Accuracy is therefore defined as the

ability of the robot to position itself to the desired location with the minimal error (usually 0.001

inch).

Repeatability

Repeatability is the ability of a robot to repeatedly position itself when asked to perform a

task multiple times. Accuracy is an absolute concept, repeatability is relative. Note that a robot

that is repeatable may not be very accurate. Likewise, an accurate robot may not be repeatable.

Precision

Precision is the fineness with which a sensor can report a value. For example, a sensor

that reads 2.1178 is more precise than a sensor that reads 2.1 for the same physical variable.

Precision is related to significant figures. The number of significant figures is limited to the least

precise number in a system of sensing or string of calculations.


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Chapter 2

INTRODUCTION TO PROJECT

2.1 Introduction

Conventionally, wireless-controlled robots use RF circuits,which have the drawbacks of

limited working range, limited frequency range and limited control. Use of a mobile phone for

robotic control can overcome these limitations. It provides the advantages of robust control,

working range as large as the coverage area of the service provider,no interference with other

controllers and up to twelve controls.Although the appearance and capabilities of robots vary

vastly, all robots share the features of a mechanical, movable structure under some form of

control. The control of robot involves three distinct phases: reception, processing and action.

Generally, the preceptors are sensors mounted on the robot, processing is done by the on-board

microcontroller or processor, and the task (action) is performed using motors or with some other

actuators.

2.2 Project Overview

In this project, the robot is controlled by a mobile phone that makes a call to the mobile

phone attached to the robot. In the course of a call, if any button is pressed,a tone corresponding

to the button pressed is heard at the other end of the call. This tone is called dual-tone multiple-

frequency (DTMF) tone. The robot perceives this DTMF tone with the help of the phone

stacked in the robot. The received tone is processed by the ATmega16 microcontroller with the

help of DTMF decoder MT8870. The decoder decodes the DTMF tone into its equivalent binary

digit and this binary number is sent to the microcontroller.The microcontroller is preprogrammed

to take a decision for any given input and outputs its decision to motor drivers in order to drive

the motors for forward or backward motion or a turn. The mobile that makes a call to the mobile

phone stacked in the robot acts as a remote. So this simple robotic project does not require the

construction of receiver and transmitter units. DTMF signaling is used fr telephone signaling

over the line in the voice-frequency band to the call switching centre. The version of DTMF used


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for telephone tone dialing is known as Touch-Tone.DTMF assigns a specific frequency

(consisting of two separatetones) to each key so that it can easily be identified by the electronic

circuit. The signal generated by the DTMF encoder is a direct algebraic summation, in real time,

of the amplitudes of two sine (cosine)waves of different frequencies, i.e., pressing 5 will send a

tone made by adding 1336 Hz and 770 Hz to the other end of the line. The tones and assignments

in a DTMF system are shown in Table I & there is a wireless camera is attached to this electronic

car. This camera is used to see the vision of external environment. This camera work to see the

outside. When this complete car is moving in a room it show the picture of this room

Fig. 2.1. DTMF system


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2.3 Scematic of cellphone operated car

Fig shows the block diagram of the microcontroller-based mobile phoneoperated land rover.

The important components of this rover are a DTMF decoder, microcontroller and motor driver.

An MT8870 series DTMF decoder is used here. All types of the MT8870 series use digital

counting techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code output.

The built-in dial tone rejection circuit eliminates the need for pre-filtering.

When the input signal given at pin 2 (IN-) in single-ended input configuration is recognised

to be effective, the correct 4-bit decode signal of the DTMF tone is transferred to Q1 (pin 11)

through Q4 (pin 14) outputs. Table II shows the DTMF data output table of MT8870. Q1 through

Q4 outputs of the DTMF decoder (IC1) are connected to port pins PA0 through PA3 of

ATmega16 microcontroller (IC2) after inversion by N1 through N4,respectively. The ATmega16

is a low-power, 8-bit, CMOS microcontroller based on the AVR enhanced RISC architecture. It

provides the following features: 16 kB of in-system programmable Flash program memory with

read-while-write capabilities, 512 bytes of EEPROM, 1kB SRAM, 32 general-purpose

input/output (I/O) lines and 32 general-purpose working registers. All the 32 registers re directly

connected to the arithmetic logic unit, allowing two independent registers to be accessed in one

single instruction executed in one clock cycle.

The resulting architecture is more code-efficient. Outputs from port pins PD0 through

PD3 and PD7 of the microcontroller are fed to inputs IN1 through IN4 and enable pins (EN1 and

EN2) of motor driver L293D, espectively, to drive two geared DC motors. Switch S1 is used for

manual reset. The microcontroller output is not sufficient to drive the DC motors, so current

drivers are required for motor rotation. The L293D is a quad, high-current, half-H driver

designed to provide bidirectional drive currents of up to 600 mA at voltages from 4.5V to 36V. It

makes it easier to drive the DC motors. The L293D consists of four drivers. Pin IN1 through IN4

and OUT1 through OUT4 are input and output pins, respectively, of driver 1 through driver 4.

Drivers 1 and 2, and drivers 3 and 4 are enabled by enable pin 1 (EN1) and pin 9 (EN2),

respectively. When enable input EN1 (pin 1) is high, drivers 1 and 2 are enabled and the outputs

corresponding to their inputs are active. Similarly, enable input EN2 (pin 9) enables drivers 3

and 4. An actual-size, single-side PCB for cellphone-operated land rover is shown in Fig.


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Fig. 2.2. Circuit diagram

2.4 Software description

The software is written in C language and compiled using CodeVision AVR C

compiler. The source program is ed into hex code by the compiler. Burn this hex code into

ATmega16 AVR microcontroller.The source program is well commented and easy to

understand. First include the register name defined specifically for ATmega16 and also declare

the variable. Set port A as the input and port D as the output. The program

will run forever by using while loop. Under while loop, read port A and test the

received input using switch statement. The corresponding data will output at port D after

testing of the received data.

2.5 WORKING

In order to control the robot, you need to make a call to the cell phone attached to the

robot (through head phone) from any phone, which sends DTMF tunes on pressing the numeric

buttons. The cell phone in the robot is kept in auto answer mode. (If the mobile does not have

the auto answering facility, receive the call by OK key on the rover-connected mobile and then

made it in hands-free mode.) So after a ring, the cellphone accepts the call. Now you may press


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any button on your mobile to perform actions . The DTMF tones thus produced are received by

the cellphone in the robot. These tones are fed to the circuit by the headset of the

Fig. 2.3 Working

cellphone. The MT8870 decodes the received tone and sends the equivalent binary

number to the microcontroller. According to the program in the microcontroller, the robot starts

moving.When you press key 2 (binary equivalent 00000010) on your mobile phone, the

microcontroller outputs 10001001 binary equivalent. Port pins PD0, PD3 and PD7 are high.

The high output at PD7 of the microcontroller drives the motor driver (L293D). Port pins PD0

and PD3 drive motors M1 and M2 in forward direction . Similarly, motors M1 and M2 move for

left turn, right turn, backward motion and stop condition .


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2.6 Construction

When constructing any robot, one major mechanical constraint is the number there a two-

wheel drive or a four-wheel ive. Though four-wheel drive is more complex than two-wheel

drive, it provides more torque and good control. Two-wheel drive, on the other hand, is very easy

to construct. Top view of a four-wheel-driven land rover is shown in Fig. 3. The chassis used in

this model is a 1018cm2 sheet made up of parax. Motors are fixed to the bottom of this sheet

and the circuit is affixed firmly on top of the sheet. A cellphone is also mounted on the sheet as

shown in the picture. In the four-wheel drive system, the two motors on a side are controlled in

parallel. So a single L293D driver IC can drive the rover. For this robot, beads affixed with glue

act as support wheels.

Fig. 2.4 Construction


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{

PORTD=086; //O/P 086 ie Backward

break;

}

case 004:

{

PORTD=085; // Left turn

break;

case 006:

{

PORTD=0x8A; // Right turn

break;

}

case 005:

{

PORTD=000; // Stop

break;

}

}

}

}


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Chapter 3

COMPONENT DESCRIPTION

3.1 Resistor

A resistor is a two-terminal passive electronic component which implements electrical

resistance as a circuit element. When a voltage V is applied across the terminals of a resistor, a

current I will flow through the resistor in direct proportion to that voltage. The reciprocal of the

constant of proportionality is known as the resistance R, since, with a given voltage V, a larger

value of R further "resists" the flow of current I as given by Ohm's law:

Fig. 3.1 Resistor

Resistors are common elements of electrical networks and electronic circuits and are

ubiquitous in most electronic equipment. Practical resistors can be made of various compounds

and films, as well as resistance wire (wire made of a high-resistivity alloy, such as nickel-

chrome). Resistors are also implemented within integrated circuits, particularly analog devices,

and can also be integrated into hybrid and printed circuits.

The electrical functionality of a resistor is specified by its resistance: common

commercial resistors are manufactured over a range of more than 9 orders of magnitude. When

specifying that resistance in an electronic design, the required precision of the resistance may


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require attention to the manufacturing tolerance of the chosen resistor, according to its specific

application.

Fig. 3.2 Carbon Film Resistor

The temperature coefficient of the resistance may also be of concern in some precision

applications. Practical resistors are also specified as having a maximum power rating which must

exceed the anticipated power dissipation of that resistor in a particular circuit: this is mainly of

concern in power electronics applications. Resistors with higher power ratings are physically

larger and may require heat sinking. In a high voltage circuit, attention must sometimes be paid

to the rated maximum working voltage of the resistor.

The series inductance of a practical resistor causes its behavior to depart from ohms law;

this specification can be important in some high-frequency applications for smaller values of

resistance. In a low-noise amplifier or pre-amp the noise characteristics of a resistor may be an

issue. The unwanted inductance, excess noise, and temperature coefficient are mainly dependent

on the technology used in manufacturing the resistor. They are not normally specified

individually for a particular family of resistors manufactured using a particular technology.[1] A

family of discrete resistors is also characterized according to its form factor, that is, the size of

the device and position of its leads (or terminals) which is relevant in the practical manufacturing

of circuits using them

3.2 Capacitor

A capacitor (formerly known as condenser) is a device for storing electric charge. The

forms of practical capacitors vary widely, but all contain at least two conductors separated by a

non-conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils

separated by a layer of insulating film.


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Fig. 3.2 Carbon Film Resistor

A capacitor is a passive electronic component consisting of a pair of conductors separated

by a dielectric (insulator). When there is a potential difference (voltage) across the conductors, a

static electric field develops across the dielectric, causing positive charge to collect on one plate

and negative charge on the other plate. Energy is stored in the electrostatic field. An ideal

capacitor is characterized by a single constant value, capacitance, measured in farads. This is the

ratio of the electric charge on each conductor to the potential difference between them.

Capacitors are widely used in electronic circuits for blocking direct current while

allowing alternating current to pass, in filter networks, for smoothing the output of power

supplies, in the resonant circuits that tune radios to particular frequencies and for many other

purposes.

The capacitance is greatest when there is a narrow separation between large areas of

conductor, hence capacitor conductors are often called "plates", referring to an early means of

construction. In practice the dielectric between the plates passes a small amount of leakage

current and also has an electric field strength limit, resulting in a breakdown voltage, while the

conductors and leads introduce an undesired inductance and resistance.


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3.3 Crystal Oscillator

A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance

of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise

frequency. This frequency is commonly used to keep track of time (as in quartz wristwatches), to

provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio

transmitters and receivers. The most common type of piezoelectric resonator used is the quartz

crystal, so oscillator circuits designed around them became known as "crystal oscillators."

Fig.3.4. Crystal Oscillator

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of

megahertz. More than two billion (2109) crystals are manufactured annually. Most are used for

consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz

crystals are also found inside test and measurement equipment, such as counters, signal

generators, and oscilloscopes.


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3.3.1. Operation

A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a

regularly ordered, repeating pattern extending in all three spatial dimensions.

Almost any object made of an elastic material could be used like a crystal, with

appropriate transducers, since all objects have natural resonant frequencies of vibration. For

example, steel is very elastic and has a high speed of sound. It was often used in mechanical

filters before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of

sound in the material. High-frequency crystals are typically cut in the shape of a simple,

rectangular plate. Low-frequency crystals, such as those used in digital watches, are typically cut

in the shape of a tuning fork. For applications not needing very precise timing, a low-cost

ceramic resonator is often used in place of a quartz crystal.

When a crystal of quartz is properly cut and mounted, it can be made to distort in an

electric field by applying a voltage to an electrode near or on the crystal. This property is known

as piezoelectricity. When the field is removed, the quartz will generate an electric field as it

returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal

behaves like a circuit composed of an inductor, capacitor and resistor, with a precise resonant

frequency. (See RLC circuit.)

Fig 3.5. Schematic diagram of crystal oscillator


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Quartz has the further advantage that its elastic constants and its size change in such a

way that the frequency dependence on temperature can be very low. The specific characteristics

will depend on the mode of vibration and the angle at which the quartz is cut (relative to its

crystallographic axes). Therefore, the resonant frequency of the plate, which depends on its size,

will not change much, either. This means that a quartz clock, filter or oscillator will remain

accurate. For critical applications the quartz oscillator is mounted in a temperature-controlled

container, called a crystal oven, and can also be mounted on shock absorbers to prevent

perturbation by external mechanical vibrations.

3.4 IC 1MT8870 DTMF DECODER

The M-8870 is a full DTMF Receiver that integrates both bandsplit filter and decoder

functions into a single 18-pin DIP or SOIC package. Manufactured using CMOS process

technology, the M-8870 offers low power consumption (35 mW max) and precise data handling.

Its filter section uses switched capacitor technology for both the high and low group filters and

for dial tone rejection. Its decoder uses digital counting techniques to detect and decode all 16

DTMF tone pairs into a 4-bit code. External component count is minimized by provision of an

on-chip differential input amplifier, clock generator, and latched tri-state interface bus. Minimal

external components required include a low-cost 3.579545 MHz color burst crystal, a timing

resistor, and a timing capacitor.

The M-8870-02 provides a power-down option which, when enabled, drops

consumption to less than 0.5 mW. The M-8870-02 can also inhibit the decoding of fourth

column digits


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3.4.1 Pin Diagram of IC1MT8870

Fig 3.6 Pin Diagram of IC1MT8870

3.4.2 Pin Functions ofMT8870


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3.4.3 Tone Decoding ofMT8870

Table 3.2 Tone Decoding ofMT8870


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3.5 ATMEGA 16 8051 MICROCONTROLLER

Microcontroller manufacturers have been competing for a long time for attracting choosy

customers and every couple of days a new chip with a higher operating frequency, more memory

and upgraded A/D converters appeared on the market.However, most of them had the same or at

least very similar architecture known in the world of microcontrollers as 8051 compatible.

What is all this about?

The whole story has its beginnings in the far 80s when Intel launched the first series of

microcontrollers called the MCS 051. Even though these microcontrollers had quite modest

features in comparison to the new ones, they conquered the world very soon and became a

standard for what nowadays is called the microcontroller.

The main reason for their great success and popularity is a skillfully chosen configuration

which satisfies different needs of a large number of users allowing at the same time constant

expansions (refers to the new types of microcontrollers). Besides, the software has been

developed in great extend in the meantime, and it simply was not profitable to change anything

in the microcontrollers basic core. This is the reason for having a great number of various

microcontrollers which basically are solely upgraded versions of the 8051 family

Fig. 3.7 Pin diagram of 8051


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As seen in figure above, the 8051 microcontroller has nothing impressive in appearance:

4 Kb of ROM is not much at all.

128b of RAM (including SFRs) satisfies the user's basic needs.

4 ports having in total of 32 input/output lines are in most cases sufficient to make all

necessary connections to peripheral environment.

The whole configuration is obviously thought of as to satisfy the needs of most

programmers working on development of automation devices. One of its advantages is that

nothing is missing and nothing is too much. In other words, it is created exactly in accordance to

the average users taste and needs. Another advantages are RAM organization, the operation of

Central Processor Unit (CPU) and ports which completely use all recourses and enable further

upgrade.

3.5.1 Pinout Description

Pins 1-8: Port 1 Each of these pins can be configured as an input or an output.

Pin 9: RS A logic one on this pin disables the microcontroller and clears the contents of most

registers. In other words, the positive voltage on this pin resets the microcontroller. By applying

logic zero to this pin, the program starts execution from the beginning.

Pins10-17: Port 3 Similar to port 1, each of these pins can serve as general input or output.

Besides, all of them have alternative functions:

Pin 10: RXD Serial asynchronous communication input or Serial synchronous communication

output.

Pin 11: TXD Serial asynchronous communication output or Serial synchronous communication

clock output.

Pin 12: INT0 Interrupt 0 input.

Pin 13: INT1 Interrupt 1 input.


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Pin 14: T0 Counter 0 clock input.

Pin 15: T1 Counter 1 clock input.

Pin 16: WR Write to external (additional) RAM.

Pin 17: RD Read from external RA

Pin 18, 19: X2, X1 Internal oscillator input and output. A quartz crystal which specifies

operating frequency is usually connected to these pins. Instead of it, miniature ceramics

resonators can also be used for frequency stability. Later versions of microcontrollers operate at

a frequency of 0 Hz up to over 50 Hz.

Pin 20: GND Ground.

Pin 21-28: Port 2 If there is no intention to use external memory then these port pins are

configured as general inputs/outputs. In case external memory is used, the higher address byte,

i.e. addresses A8-A15 will appear on this port. Even though memory with capacity of 64Kb is

not used, which means that not all eight port bits are used for its addressing, the rest of them are

not available as inputs/outputs.

Pin 29: PSEN If external ROM is used for storing program then a logic zero (0) appears on it

every time the microcontroller reads a byte from memory.

Pin 30: ALE Prior to reading from external memory, the microcontroller puts the lower address

byte (A0-A7) on P0 and activates the ALE output. After receiving signal from the ALE pin, the

external register (usually 74HCT373 or 74HCT375 add-on chip) memorizes the state of P0 and

uses it as a memory chip address. Immediately after that, the ALU pin is returned its previous

logic state and P0 is now used as a Data Bus. As seen, port data multiplexing is performed by

means of only one additional (and cheap) integrated circuit. In other words, this port is used for

both data and address transmission

Pin 31: EA By applying logic zero to this pin, P2 and P3 are used for data and address

transmission with no regard to whether there is internal memory or not. It means that even there

is a program written to the microcontroller, it will not be executed. Instead, the program written


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Port 1

P1 is a true I/O port, because it doesn't have any alternative functions as is the case with

P0, but can be cofigured as general I/O only. It has a pull-up resistor built-in and is completely

compatible with TTL circuits.

Port 2

P2 acts similarly to P0 when external memory is used. Pins of this port occupy addresses

intended for external memory chip. This time it is about the higher address byte with addresses

A8-A15. When no memory is added, this port can be used as a general input/output port showing

features similar to P1.

Port 3

All port pins can be used as general I/O, but they also have an alternative function. In

order to use these alternative functions, a logic one (1) must be applied to appropriate bit of the

P3 register. In tems of hardware, this port is similar to P0, with the difference that its pins have a

pull-up resistor built-in.

Pin's Current limitations

When configured as outputs (logic zero (0)), single port pins can receive a current of

10mA. If all 8 bits of a port are active, a total current must be limited to 15mA (port P0: 26mA).

If all ports (32 bits) are active, total maximum current must be limited to 71mA. When these pins

are configured as inputs (logic 1), built-in pull-up resistors provide very weak current, but strong

enough to activate up to 4 TTL inputs of LS series.

3.6 IC L293D

L293D is a dual H-Bridge motor driver, so with one IC we can interface two DC motorswhich can be controlled in both clockwise and counter clockwise direction and if you have

motor with fix direction of motion. You can make use of all the four I/Os to connect up to four

DC motors.


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L293D has output current of 600mA and peak output current of 1.2A per channel.

Moreover for protection of circuit from back EMF output diodes are included within the IC. The

output supply (VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice

for DC motor driver.

3.6.1 Pin configuration

Fig. 3.8. Pin configuration


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3.6.2. Electrical Characteristic

Table 3.3 Electrical Characteristic

y Supply voltage(Vss) is the Voltage at which we wish to drive the motor. Generally weprefer 6V for dc motor and 6 to 12V for gear motor, depending upon the rating of the

motor.

y Logical Supply Voltage will decide what value of input voltage should be considered ashigh or low .So if we set Logical Supply Voltage equals to +5V, then -0.3V to 1.5V will

be considered as Input Low Voltage and 2.3 V to 5V will be considered as Input High

Voltage.

y L293D has 2 Channels .One channel is used for one motor.Channel 1 - Pin 1 to 8

Channel 2 - Pin 9 to 16

y Enable Pin is use to enable or to make a channel active .Enable pin is also called as ChipInhibit Pin. All Input(Pin No. 2,7,10and 15) of L293D IC is the output from

microcontroller (ATmega8).


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y Eg-We connected (Pin No. 2, 7, 10 and 15) of L293D IC to (Pin No. 14,15,16and 17) ofATmega8 respectively in our robots, because on pin 14 and 15 of ATmega8 we can

generate PWM. All Output (Pin No. 3, 6,11and 14) of L293D IC goes to the input of

Right and Left motor through RMC(4 pin Connector).

Fig 3.9.Motor Driving Circuit

3.6.3Motor Driving Table

Table 3.4 Motor Driving Table


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Characteristics

OUTPUT 1 --- Negative Terminal of Right Motor

OUTPUT 2 --- Positive Terminal of Right Motor

OUTPUT 3 --- Positive Terminal of Left Motor

OUTPUT 4 --- Negative Terminal of Left Motor

3.7 Wireless Camera

Wireless security cameras are closed-circuit television (CCTV) cameras that transmit a

video and audio signal to a wireless receiver through a radio band. Many wireless security

cameras require at least one cable or wire for power; "wireless" refers to the transmission of

video/audio. However, some wireless security cameras are battery-powered, making the cameras

truly wireless from top to bottom.

Wireless cameras are proving very popular among modern security consumers due to

their low installation costs (there is no need to run expensive video extension cables) and flexible

mounting options; wireless cameras can be mounted/installed in locations previously unavailable

to standard wired cameras

3.7.1.Types of Wireless Security Cameras

Analog wireless

Analog wireless is the transmission of audio and video signals using radio frequencies.

Typically, analog wireless has a transmission range of around 300 feet (91 meters) in open space;

walls, doors, and furniture will reduce this range.

Types of Analog wireless Analog wireless is found in three frequencies: 900 MHz, 2.4

GHz, and 5.8 GHz. Currently, the majority of wireless security cameras operate on the 2.4 GHz

frequency. Most household routers, cordless phones, video game controllers, and microwaves

operate on the 2.4 GHz frequency and may cause interference with your wireless security

camera. 900 MHz is known as Wi-Fi Friendly because it will not interfere with the Internet

signal of your wireless network.


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Pros

Affordable: the cost of individual cameras is low Multiple receivers per camera: the

signal from one camera can be picked up by any receiver; you can have multiple receivers in

various locations to create your wireless surveillance network

Cons

Susceptible to interference from other household devices, such as microwaves, cordless

phones, video game controllers, and routers Signal is not secureneighbors can pick up the

transmission on their radios or other devices on a similar bandwidth Quality of video and audio

is average/poor; image can degrade significantly with interference

Digital wireless cameras

Digital wireless is the transmission of audio and video analog signals encoded as digital

packets over high-bandwidth radio frequencies.

Pros

100% secure: neighbors cannot pick up the signal on a radio Wide transmission range

usually close to 450 feet (open space, clear line of sight between camera and receiver) High

quality video and audio Two-way communication between the camera and the receiver Digital

signal means you can transmit commands and functions, such as turning lights on and off You

can connect multiple receivers to one recording device, such as security DVR

Cons

Usually more expensive than similar analog setup


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3.7.2 Uses and Applications

Wireless security cameras are becoming more and more popular in the consumer market.

They are a cost-effective way to have a comprehensive surveillance system in your home or

business without needing an expensive installation. Wireless cameras are also a great for people

renting homes or apartments. Since there is no need to run video extension cables through walls

or ceilings (from the camera to the receiver or recording device) one does not need approval of a

landlord to install a wireless security camera system.

A wireless security camera is also a great option for seasonal monitoring and

surveillance. You can observe your pool or patio in the summer months and take down the

camera in the winter.

3.7.3.Wireless range

Wireless security cameras function best when there is a clear line of sight between the

camera(s) and the receiver. Outdoors, and with clear line of sight, digital wireless cameras

typically have a range between 250 to 450 feet. Indoors, the range can be limited to 100 to 150

feet. The signal range varies depending on the type of building materials and/or objects the

wireless signal must pass through.


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CONCLUSION

The main aim of our project was to put our knowledge into the practical use. This project has

given us the experience to work in the actual field and it also helped me in getting information

about the basic philosophies, process circuits and other building blocks of electronics.

This project report is a brief description about our work done on our project

In this project report we have discussed about the microcontroller based electronic car which

having a wireless camera which show the images of external environment.

Lastly we would like to say that this project is helped us to shape the practica knowledge and it

would also help us throughout our life.


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REFERENCE

y www.wikipedia.orgy www.google.com

Documents

Report on Wireless Robot