Project Report

on

“CRASH PROTECTION ”

SUBMITTED IN PARTIAL FULFILLMENT OF REQUIRED FOR B-

TECH IN “Electronics & communication” under Punjab state board of

technical education and industrial training Chandigarh

Submitted by:-

RIMT

(Mandi Gobindgarh)

Submitted To:-

DEPARTMENT OF “ ELECTRONICS AND COMMUNICATION”

RIMT- Near floating side, Mandi Gobindgarh. Punjab (147301)

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ON

CRASH PROTECTION

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INDEX

SR. NO. CHAPTER NAME PAGE NO.

1 Acknowledgement 4

2 Introduction 5

3 Component List

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4 Block Diagram

Mechanical drawing and description

Power Supply 12

6 Microcontroller 13

7 Circuit and working

Advantage

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11 Disadvantage 33

12 Application 34

13 Precaution 35

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CHAPTER – 1

ACKNOWLEDGEMENT

Many individual have proudly influenced us during our Studies (B.E) at

RIMT ENGINEERING College,Mandi Gobindgarh and it is pleasure to

acknowledge their guidance and support. At RIMT Polytechnic, We learned

many things like the project training is mainly aimed at enabling the student

to apply their theoretical knowledge to practical as "The theory is to know

how and practical is to do how" and to appreciate the limitation of

knowledge gained in the class room to practical situation and to appreciate

the importance of discipline, punctuality, team work, sense of responsibility,

money, value of time, dignity of labour.

I will like to express my gratitude towards Mrs. Talwar who took

keen interest in our project, who helped me in every possible way and is

source of inspiration for all the group members.

I would also like to thank Mr. Talwar (HOD), Electronics &

Communication who motivated us to complete our project with enthusiasm

and hard work.

Components:-

Iron Strip Lenth-10 fit, depth-30mm and width-12mm

Iron Strip Lenth- 2 fit, Depth-25mm and width-6mm

1. diode 4007 22. 1000uF, 25 V 1

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3. 470uF, 16 V 14. 7805 15. LED 16. 470 ohm 1

1. 40 pin base 12. 12 Mhz 13. 22 pF 24. 89s52 15. 10uF, 10 V 16. 10K 1

1. 8 Pin base 22. 817 23. 1K 24. 470 ohm 25. 4.7 K 26. 547 27. 558 2Bateery 2Battery connecter 2Motor Dc gear 2

PROCREDURE TO MAKE PROJECT:-

1. IDEA OF PROJECT

In this stage student select the topic of the project of the

project. It’s the main stage of project work.its the area where

talented students shows their innovative ideas. Innovative

students make project with a new idea then others. We

selected this project because we want to do something in with

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our own hands. We drop idea because there was little bit

practical.

2. STUDY RAW MATERIAL AND LAYOUT DIAGRAM

In this section we collected the study Raw Material. We

searches about our project on

google.com,www.yahoo.com,www.msn.com and

www.ludhianaprojects.com. But we find many Layout and

theory Raw Materials for our project. We were not sure about

the Layout and Raw Material used in it. Because Layout

diagram available on the site were provided by students. So we

can really on them. Then we saw www.ludhianaprojects.com a

project help provider site. Its help us lot. They helped us lot in

our project. We find the proper layout Project of our project in

that site.

3. Trail TESTING OF MAIN PROJECT- Then we collect the Raw

Material of project. It was not a easy task. Because no shop in

our area have all parts used in projects. Then after collection of

Raw Material we test the projects working by temporary made

project.- step by step. Because we want to sure about the

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Project. We checked it in different steps beacuuse it was a big

project and was not possible to check it in a single step.

4. COMPONENT MOUNTING- we have also some parts of

electronic circuit. So we kept the pcb for circuit with hole size

from 0.8mm yo 1 mm for leads of Raw Material. Then we insert

Raw Material according ton their pitches.

5. SODERING- Afgter mounting Raw Raw Material we solder the

Raw Raw Material ane by one. We kept the temperature of iron

at 250 degree to 400 degree. Because above this temperature

it can damage to component. We used general iron available in

the market of siron company. Its temperature was nearly 350

degree acc to company specifications. We used soldering wire

of 22 gauge with flux inbuilt.

6. Assembly of Project:- after making electronic circuit we make

mechanical portion. For this we take a base Board and after

this our first step is that we make iron work that is welding,

turning and etc. after this assembly of mechanical portion. After

making mechanical portion we connect electronic circuit to

make it automatic functions.

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7. FINAL TESTING- After that we test the Project step by step .

and insert the ICs after testing the one portion of the Project an

then after other step by step. Its was tough work we tested

voltage across the compents with erepect to ground. And

current in series.

TROUBLSHOOTING- Then we tried to troubleshoot the errors

in the project

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CHAPTER –2

INTRODUCTION

In this project we use will control train with IR sensor. This sensor have

transmitter and receiver and its working is based on the reflected rays.

sensor will give signal to microcontroller . Microcontroller will give that

data to relay drive circuit or H bride circuit.

If H brude will good enough to give sufficient current to motors then we will

use H- bridge circuit. If not then we will use relay circuit to operate motors.

We will use opto-couplers in between micron roller and H bridge circuit.

In this project we will control train with infrared in will be stopped. We will

control auto stop function of moving train . In this project we will use IR

sensor at the front of train. We can use more other sensor against IR sensor

but it is less in cost so we use it. Normally we will provide supply to IR

transmitter and it emits the frequency rays in invisible form. When any train

or other thing will be in front of train then sensor will work and with the

help of microcontroller motor supply will be disconnected . We will use

89c051 microcontroller for this function. We will give 9v supply to remote

with 9v dc battery available in the market. We will use 7805 voltage

regulator for 5v dc supply. For input to microcontroller there will be

microswitches. There will be complementary push pull power amplifier after

Microcontroller output.

For that we will use 548 npn transistors 558 pnp. It will amplify data so that

it will not destroy in the way. After that it will be amplify and led will

convert that signal into phpt signal . On reciver end photodide will amplify

that signal and will give it to microcontroller. Microcontroller will give

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signal to optocoupler. Here optocoupler will worl as a isolator after that h

bridge will amplify that signal and will give signal according to rxed signal

Automation requires precisely rotating motor which accelerates / decelerates very fast & stops at precise predetermined position without any error, and also has holding torque so that the motor-shaft position is maintained. AUTO CONTROLS make stepper motor controllers are based on H-bridge configuration with facility of having constant current supplied to the motor.

Stepper motor controllers are MOSFET based and utilize  high voltage D.C. Supply at constant current mode. Hence, the stepper motor can run at higher speed up to 1000 rpm and above. Stepper motor controllers can achieve the acceleration of 100 m/Sec2. to zero speed to stop the motor from running speed, with rated torque. The time of Acc & Dec. will vary as per the load and GD2 of the load to overcome inertia force.

Basic:-

COMPONENTS

DIODE

When a p-type semi conductor is suitably joined to an n-type semi

conductor, the contact surface so formed is called p-junction. A p-n junction

is known as semi conductor diode.

It is known as crystal diode since it is grown out of a crystal. A semi

conductor diode has two terminals. It conducts only when it is formed biased

i.e. when terminal connected with arrowhead is at higher potential than the

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terminal connected to the bar. However, when it is reversed biased,

practically it does not conduct any current through it.

ZENER DIODE

A specially designed silicon diode, which is optimized, to operate in

the breakdown region is known as Zener diode.

The ordinary rectifier and small signal diodes are never intentionally

operated in the breakdown region s known because this may damage them.

On the other hand Zener diodes are only operated in the breakdown region.

Therefore, Zener diodes are cryptically designed to have a sharp breakdown

voltage. By varying the doping levels of silicon diode, a manufacturer can

produce Zener diode with breakdown voltages from about 2 to 200V.

RESISTORS

Resistor is a component, used to limit the amount of current or divide

the voltage in an electronic circuit. The ability of a resistor to oppose the

current is called resistance R is Ohm.

Each resistor has two main characteristics i.e. its resistance (R) in

ohms and its power rating in watts (W). the resistors having wide range of

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resistance ( from a fraction of an ohm to many mega ohms ) are available.

The power rating may be as lower 1/10 W to as high a several hundred

watts. The value of R is selected to obtain a desired current I or voltage drop

IR in the circuit. At the same time wattage of the resistor is to select so that

it can dissipate the heat losses without overheating itself.

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CAPACITORS

The two conducting plates separated by an insulating material (called

dielectric) from a capacitor. The basic purpose of the capacitor is to store the

charge. The capacity of a capacitor to store per unit potential difference is

called its capacitance. The unit of capacitance of farads ( F ).

A capacitor is a component, which offers low impedance to AC but very

high. Impedance ( resistance ) to DC. In most of the electronic circuits, a

capacitor has dc voltage applied, combined with a much smaller AC signal

voltage. The usual function of the capacitor is to block DC voltage but pass

the AC signal voltage, by means of charging and discharging. These

application include coupling, bypassing for AC signal.

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TRANSISTORS

A semiconductor device consisting of two p-n junctions formed by a special

technique is adopted to form a transistor either p-type or n-type semi

conductors between a pair of opposite types is a transistor. There are two

types of transistors:

PNP transistor & NPN transistor.

RELAY

Working of relay or two-way switch is of same type. The only difference is

that the two-way switches is operated manually but relay works on magnetic

field. In relay one coil is used to produce magnetic power. When voltage is

induced in coils magnetic field is produced. The terminals connected to

magnetic coils are connected to base plate switches on and off points of

relay. Coil is made on iron core by this electromagnetic field. The two points

of coil on which voltages are given are put at outer base plate of relay and

the relay is made on iron stand and stretched by the ‘spring is kept b/w the

two points of switch.

A and B is a coil. The pole D is connected to the switch C, when there is no

supply to the coil. This condition is known as normal connection (N/C). but

when the supply is given to the coil, the core of coil becomes

electromagnetic pole and connects the pole D with switch E. in this

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condition switch E is known as orderly connection (O/C).When the supply is

off. The core of supply is demagnetized; resulting in reconnection of pole D

with switch C. relay can operate on AC as well as DC.

There are many types of relays such as;

1. Many relays control only one phase i.e. have only one on/off contact.

2. Many relays can control two phase or both phase and neutral.

ON/OFF SWITCH

It makes the supply or total fluctuations of the switches ON/OFF.

NEON INDICATING LAMP

When the switch is made on this neon lamp gives light to indicate that the

main switch is made on. When it does not give any light this indicate that

switch is off.

TRANSFORMER

A transformer is just similar in appearance to an indicator. Basically, it

consists of two coils having the same core. The coil to which supply is

connected, is called primary winding and the coil to which load is

connected, is called secondary winding. When an AC supply is applied to

primary an e.m.f. is induced in the secondary side. Thus, transformer is a

static device, which transfers power from one to other circuit.

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Depending upon the number of turns on the secondary and primary side, a

transformer may be step up or step down. In electronics circuits, the

transformers, which are generally used, are known as power transformers,

o/p transformers and intermediate frequency transformers.

LEDs

Light Emitting Diodes (LEDs)

Colours | Sizes and shapes | Resistor value | LEDs in series | LED   data  | Flashing | Displays

Example:        Circuit symbol:   

FunctionLEDs emit light when an electric current passes through them.

Connecting and solderingLEDs must be connected the correct way round, the diagram may be labelled a or + for anode and k or - for cathode (yes, it really is k, not c, for cathode!). The cathode is the short lead and there may be a slight flat on the body of round LEDs. If you can see inside the LED the cathode is the larger electrode (but this is not an official identification method).

LEDs can be damaged by heat when soldering, but the risk is small unless you are very slow. No special precautions are needed for soldering most

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LEDs.

Testing an LEDNever connect an LED directly to a battery or power supply! It will be destroyed almost instantly because too much current will pass through and burn it out.

LEDs must have a resistor in series to limit the current to a safe value, for quick testing purposes a 1k resistor is suitable for most LEDs if your supply voltage is 12V or less. Remember to connect the LED the correct way round!

For an accurate value please see Calculating an LED resistor value below.

Colours of LEDsLEDs are available in red, orange, amber, yellow, green, blue and white. Blue and white LEDs are much more expensive than the other colours.

The colour of an LED is determined by the semiconductor material, not by the colouring of the 'package' (the plastic body). LEDs of all colours are available in uncoloured packages which may be diffused (milky) or clear (often described as 'water clear'). The coloured packages are also available as diffused (the standard type) or transparent.

Tri-colour LEDsThe most popular type of tri-colour LED has a red and a green LED combined in one package with three leads. They are called tri-colour because mixed red and green light appears to be yellow and this is produced when both the red and green LEDs are on.

The diagram shows the construction of a tri-colour LED. Note the different lengths of the three leads. The centre lead (k) is the common cathode for both LEDs, the outer leads (a1 and a2) are the anodes to the LEDs allowing

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each one to be lit separately, or both

Bi-colour LEDsA bi-colour LED has two LEDs wired in 'inverse parallel' (one forwards, one backwards) combined in one package with two leads. Only one of the LEDs can be lit at one time and they are less useful than the tri-colour LEDs described above.

Sizes, Shapes and Viewing angles of LEDsLEDs are available in a wide variety of sizes and shapes. The 'standard' LED has a round cross-section of 5mm diameter and this is probably the best type for general use, but 3mm round LEDs are also popular.

Round cross-section LEDs are frequently used and they are very easy to install on boxes by drilling a hole of the LED diameter, adding a spot of glue will help to hold the LED if necessary. LED clips are also available to secure LEDs in holes. Other cross-section shapes include square, rectangular and triangular.

As well as a variety of colours, sizes and shapes, LEDs also vary in their viewing angle. This tells you how much the beam of light spreads out. Standard LEDs have a viewing angle of 60° but others have a narrow beam of 30° or less.

Rapid Electronics stock a wide selection of LEDs and their catalogue is a good guide to the range available.

Calculating an LED resistor value

LED Clip

Photograph © Rapid Electronics

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An LED must have a resistor connected in series to limit the current through the LED, otherwise it will burn out almost instantly.

The resistor value, R is given by:

R = (VS - VL) / I

VS = supply voltage VL = LED voltage (usually 2V, but 4V for blue and white LEDs) I = LED current (e.g. 20mA), this must be less than the maximum permitted

If the calculated value is not available choose the nearest standard resistor value which is greater, so that the current will be a little less than you chose. In fact you may wish to choose a greater resistor value to reduce the current (to increase battery life for example) but this will make the LED less bright.

For exampleIf the supply voltage VS = 9V, and you have a red LED (VL = 2V), requiring a current I = 20mA = 0.020A, R = (9V - 2V) / 0.02A = 350 , so choose 390 (the nearest standard value which is greater).

Working out the LED resistor formula using Ohm's lawOhm's law says that the resistance of the resistor, R = V/I, where:   V = voltage across the resistor (= VS - VL in this case)   I = the current through the resistor

So   R = (VS - VL) / I

For more information on the calculations please see the Ohm's Law page.

Connecting LEDs in seriesIf you wish to have several LEDs on at the same time it may be possible to connect them in series. This prolongs battery life by lighting several LEDs with the same current as just one LED.

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All the LEDs connected in series pass the same current so it is best if they are all the same type. The power supply must have sufficient voltage to provide about 2V for each LED (4V for blue and white) plus at least another 2V for the resistor. To work out a value for the resistor you must add up all the LED voltages and use this for VL.

Example calculations: A red, a yellow and a green LED in series need a supply voltage of at least 3 × 2V + 2V = 8V, so a 9V battery would be ideal. VL = 2V + 2V + 2V = 6V (the three LED voltages added up). If the supply voltage VS is 9V and the current I must be 15mA = 0.015A, Resistor R = (VS - VL) / I = (9 - 6) / 0.015 = 3 / 0.015 = 200 , so choose R = 220 (the nearest standard value which is greater).

Avoid connecting LEDs in parallel!Connecting several LEDs in parallel with just one resistor shared between them is generally not a good idea.

If the LEDs require slightly different voltages only the lowest voltage LED will light and it may be destroyed by the larger current flowing through it. Although identical LEDs can be successfully connected in parallel with one resistor this rarely offers any useful benefit because resistors are very cheap and the current used is the same as connecting the LEDs individually. If

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LEDs are in parallel each one should have its own resistor.

Reading a table of technical data for LEDsSuppliers' catalogues usually include tables of technical data for components such as LEDs. These tables contain a good deal of useful information in a compact form but they can be difficult to understand if you are not familiar with the abbreviations used.

The table below shows typical technical data for some 5mm diameter round LEDs with diffused packages (plastic bodies). Only three columns are important and these are shown in bold. Please see below for explanations of the quantities.

Type Colour IF

max.VF

typ.VF

max.VR

max.Luminousintensity

Viewingangle Wavelength

Standard Red 30mA 1.7V 2.1V 5V 5mcd @ 10mA 60° 660nm

Standard Bright red 30mA 2.0V 2.5V 5V 80mcd @

10mA 60° 625nm

Standard Yellow 30mA 2.1V 2.5V 5V 32mcd @ 10mA 60° 590nm

Standard Green 25mA 2.2V 2.5V 5V 32mcd @ 10mA 60° 565nm

High intensity Blue 30mA 4.5V 5.5V 5V 60mcd @

20mA 50° 430nm

Super bright Red 30mA 1.85V 2.5V 5V 500mcd @

20mA 60° 660nm

Low current Red 30mA 1.7V 2.0V 5V 5mcd @

2mA 60° 625nm

IF max. Maximum forward current, forward just means with the LED connected correctly.

VF typ. Typical forward voltage, VL in the LED resistor calculation. This is about 2V, except for blue and white LEDs for which it is about 4V.

VF max. Maximum forward voltage.

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VR max. Maximum reverse voltage You can ignore this for LEDs connected the correct way round.

Luminous intensity

Brightness of the LED at the given current, mcd = millicandela.

Viewing angle Standard LEDs have a viewing angle of 60°, others emit a narrower beam of about 30°.

Wavelength The peak wavelength of the light emitted, this determines the colour of the LED. nm = nanometer.

Flashing LEDsFlashing LEDs look like ordinary LEDs but they contain an integrated circuit (IC) as well as the LED itself. The IC flashes the LED at a low frequency, typically 3Hz (3 flashes per second). They are designed to be connected directly to a supply, usually 9 - 12V, and no series resistor is required. Their flash frequency is fixed so their use is limited and you may prefer to build your own circuit to flash an ordinary LED, for example our Flashing   LED project which uses a 555 astable circuit.

LED DisplaysLED displays are packages of many LEDs arranged in a pattern, the most familiar pattern being the 7-segment displays for showing numbers (digits 0-9). The pictures below illustrate some of the popular designs:

Bargraph 7-segment Starburst Dot matrixPhotographs © Rapid Electronics

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Pin connections of LED displaysThere are many types of LED display and a supplier's catalogue should be consulted for the pin connections. The diagram on the right shows an example from the Rapid Electronics catalogue. Like many 7-segment displays, this example is available in two versions: Common Anode (SA) with all the LED anodes connected together and Common Cathode (SC) with all the cathodes connected together. Letters a-g refer to the 7 segments, A/C is the common anode or cathode as appropriate (on 2 pins). Note that some pins are not present (NP) but their position is still numbered.

Also see: Display Drivers.

MOTOR:-

An electric motor converts electrical energy into mechanical energy. The

reverse task, that of converting mechanical energy into electrical energy, is

accomplished by a generator or dynamo. Traction motors used on

locomotives often perform both tasks if the locomotive is equipped with

dynamic brakes. Electric motors are found in household appliances such as

fans, exhaust fans, fridges, washing machines, pool pumps and fan-forced

ovens.

Most electric motors work by electromagnetism, but motors based on other

electromechanical phenomena, such as electrostatic forces and the

piezoelectric effect, also exist. The fundamental principle upon which

Pin connections diagram© Rapid Electronics

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electromagnetic motors are based is that there is a mechanical force on any

current-carrying wire contained within a magnetic field. The force is

described by the Lorentz force law and is perpendicular to both the wire and

the magnetic field. Most magnetic motors are rotary, but linear motors also

exist. In a rotary motor, the rotating part (usually on the inside) is called the

rotor, and the stationary part is called the stator. The rotor rotates because

the wires and magnetic field are arranged so that a torque is developed about

the rotor's axis. The motor contains electromagnets that are wound on a

frame. Though this frame is often called the armature, that term is often

erroneously applied. Correctly, the armature is that part of the motor across

which the input voltage is supplied. Depending upon the design of the

machine, either the rotor or the stator can serve as the armature.

A simple DC electric motor. When the coil is powered, a magnetic field is

generated around the armature. The left side of the armature is pushed away

from the left magnet and drawn toward the right, causing rotation.

BLOCK DIAGRAM:-

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Mechanical Portion:-

Track for train

SensorsPhotodiode or photo transistors

Programmable IC 89c51

Motor control circuit

DC Motors

Wheels of the Train

Power supply

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Train

Wheel system

A wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle, overcomes friction by facilitating motion by rolling. In order for wheels to rotate, a moment needs to be applied to the wheel about its axis, either by way of gravity, or by application of another external force. More generally the term is also used for other circular objects that rotate or turn, such as a ship's wheel, steering wheel and flywheel

Timeline

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Bronze Age disk wheel as depicted on the Standard of Ur (ca. 2500 BC)

Classical Greek four-spoked chariot-wheel (as a Linear B glyph), in use from the 15th century BC. Hittite and Egyptian chariots tended to have six spokes, Iron Age Assyrian ones eight.

Bronze Age "wheel pendants" of the Urnfield culture (ca. 1200 BC), found in Zürich (Swiss National Museum)

An Early Iron Age spoked wheel from Choqa Zanbil (ca. 1000 BC, National Museum of Iran)

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Wheel of the Etruscan chariot (ca. 530 BC)

The classic spoked wheel with hub and iron rim, in use from about 500 BC (Iron Age Europe) until the 20th century AD

Penny-farthing bicycle (1882)

Modern motorcycle alloy wheel with inflatable tire and disc brake

Michelin's "Tweel" airless tyre (2005)

[edit] Mechanics and function

The wheel is a device that enables efficient movement of an object across a surface where there is a force pressing the object to the surface. Common examples are a cart pulled by a horse, and the rollers on an aircraft flap mechanism.

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Wheels are used in conjunction with axles, either the wheel turns on the axle, or the axle turns in the object body. The mechanics are the same in either case.

The low resistance to motion (compared to dragging) is explained as follows (refer to friction):

the normal force at the sliding interface is the same. the sliding distance is reduced for a given distance of travel. the coefficient of friction at the interface is usually lower.

Bearings are used to help reduce friction at the interface. In the simplest and oldest case the bearing is just a round hole through which the axle passes (a "plain bearing").

Example:

If a 100 kg object is dragged for 10 m along a surface with the coefficient of friction μ = 0.5, the normal force is 981 N and the work done (required energy) is (work=force x distance) 981 × 0.5 × 10 = 4905 joules.

Now give the object 4 wheels. The normal force between the 4 wheels and axles is the same (in total) 981 N. Assume, for wood, μ = 0.25, and say the wheel diameter is 1000 mm and axle diameter is 50 mm. So while the object still moves 10 m the sliding frictional surfaces only slide over each other a distance of 0.5 m. The work done is 981 × 0.25 × 0.5 = 123 joules; the friction is reduced to 1/40 of that of dragging.

Additional energy is lost from the wheel-to-road interface. This is termed rolling resistance which is predominantly a deformation loss.

A wheel can also offer advantages in traversing irregular surfaces if the wheel radius is sufficiently large compared to the irregularities.

The wheel alone is not a machine, but when attached to an axle in conjunction with bearing, it forms the wheel and axle, one of the simple machines. A driven wheel is an example of a wheel and axle. Note that wheels pre-date driven wheels by about 6000 years.

[edit] Stability

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Static stability of a wheeled vehicle

For unarticulated wheels, climbing obstacles will cause the body of the vehicle to rotate. If the rotation angle is too high, the vehicle will become statically unstable and tip over. At high speeds, a vehicle can become dynamically unstable, able to be tipped over by an obstacle smaller than its static stability limit. Without articulation, this can be an impossible position from which to recover.

For front-to-back stability, the maximum height of an obstacle which an unarticulated wheeled vehicle can climb is a function of the wheelbase and the horizontal and vertical position of the center of mass (CM).

The critical angle is the angle at which the center of mass of the vehicle begins to pass outside of the contact points of the wheels. Past the critical angle, the reaction forces at the wheels can no longer counteract the moment created by the vehicle's weight, and the vehicle will tip over. At the critical angle, the vehicle is marginally stable. The critical angle θcrit can be found by solving the equation:

where

xcm is the horizontal distance (on level terrain) of the center of mass from the lower axle; and

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ycm is the vertical distance (on level terrain) of the center of mass from lower axle.

The maximum height h of an obstacle can thus be found by the equation:

where w is the wheelbase.

Gear system:-

Gears

A gear is a component within a transmission device that transmits

rotational force to another gear or device. A gear is different from a

pulley in that a gear is a round wheel which has linkages ("teeth" or

"cogs") that mesh with other gear teeth, allowing force to be fully

transferred without slippage. Depending on their construction and

arrangement, geared devices can transmit forces at different speeds,

torques, or in a different direction, from the power source. Gears are a

very useful simple machine. The most common situation is for a gear to

mesh with another gear, but a gear can mesh with any device having

compatible teeth, such as linear moving racks. A gear's most important

feature is that gears of unequal sizes (diameters) can be combined to

produce a mechanical advantage, so that the rotational speed and

torque of the second gear are different from that of the first. In the

context of a particular machine, the term "gear" also refers to one

particular arrangement of gears among other arrangements (such as

"first gear"). Such arrangements are often given as a ratio, using the

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number of teeth or gear diameter as units. The term "gear" is also used

in non-geared devices which perform equivalent tasks:

"...broadly speaking, a gear refers to a ratio of engine shaft speed

to driveshaft speed. Although CVTs change this ratio without

using a set of planetary gears, they are still described as having

low and high "gears" for the sake of

General

The smaller gear in a pair is often called the pinion; the larger, either

the gear, or the wheel.

Mechanical advantage

The interlocking of the teeth in a pair of meshing gears means that their

circumferences necessarily move at the same rate of linear motion (eg.,

metres per second, or feet per minute). Since rotational speed (eg.

measured in revolutions per second, revolutions per minute, or radians

per second) is proportional to a wheel's circumferential speed divided by

its radius, we see that the larger the radius of a gear, the slower will be

its rotational speed, when meshed with a gear of given size and speed.

The same conclusion can also be reached by a different analytical

process: counting teeth. Since the teeth of two meshing gears are locked

in a one to one correspondence, when all of the teeth of the smaller gear

have passed the point where the gears meet -- ie., when the smaller gear

has made one revolution -- not all of the teeth of the larger gear will

have passed that point -- the larger gear will have made less than one

revolution. The smaller gear makes more revolutions in a given period

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of time; it turns faster. The speed ratio is simply the reciprocal ratio of

the numbers of teeth on the two gears.

(Speed A * Number of teeth A) = (Speed B * Number of teeth B)

This ratio is known as the gear ratio.

The torque ratio can be determined by considering the force that a

tooth of one gear exerts on a tooth of the other gear. Consider two teeth

in contact at a point on the line joining the shaft axes of the two gears.

In general, the force will have both a radial and a circumferential

component. The radial component can be ignored: it merely causes a

sideways push on the shaft and does not contribute to turning. The

circumferential component causes turning. The torque is equal to the

circumferential component of the force times radius. Thus we see that

the larger gear experiences greater torque; the smaller gear less. The

torque ratio is equal to the ratio of the radii. This is exactly the inverse

of the case with the velocity ratio. Higher torque implies lower velocity

and vice versa. The fact that the torque ratio is the inverse of the

velocity ratio could also be inferred from the law of conservation of

energy. Here we have been neglecting the effect of friction on the torque

ratio. The velocity ratio is truly given by the tooth or size ratio, but

friction will cause the torque ratio to be actually somewhat less than the

inverse of the velocity ratio.

In the above discussion we have made mention of the gear "radius".

Since a gear is not a proper circle but a roughened circle, it does not

have a radius. However, in a pair of meshing gears, each may be

33

considered to have an effective radius, called the pitch radius, the pitch

radii being such that smooth wheels of those radii would produce the

same velocity ratio that the gears actually produce. The pitch radius can

be considered sort of an "average" radius of the gear, somewhere

between the outside radius of the gear and the radius at the base of the

teeth.

The issue of pitch radius brings up the fact that the point on a gear

tooth where it makes contact with a tooth on the mating gear varies

during the time the pair of teeth are engaged; also the direction of force

may vary. As a result, the velocity ratio (and torque ratio) is not,

actually, in general, constant, if one considers the situation in detail,

over the course of the period of engagement of a single pair of teeth. The

velocity and torque ratios given at the beginning of this section are valid

only "in bulk" -- as long-term averages; the values at some particular

position of the teeth may be different.

It is in fact possible to choose tooth shapes that will result in the velocity

ratio also being absolutely constant -- in the short term as well as the

long term. In good quality gears this is usually done, since velocity ratio

fluctuations cause undue vibration, and put additional stress on the

teeth, which can cause tooth breakage under heavy loads at high speed.

Constant velocity ratio may also be desirable for precision in

instrumentation gearing, clocks and watches. The involute tooth shape

is one that results in a constant velocity ratio, and is the most commonly

used of such shapes today.

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Comparison with other drive mechanisms

The definite velocity ratio which results from having teeth gives gears

an advantage over other drives (such as traction drives and V-belts) in

precision machines such as watches that depend upon an exact velocity

ratio. In cases where driver and follower are in close proximity gears

also have an advantage over other drives in the reduced number of

parts required; the downside is that gears are more expensive to

manufacture and their lubrication requirements may impose a higher

operating cost.

The automobile transmission allows selection between gears to give

various mechanical advantages.

Spur gears

Spur gears are the simplest, and probably most common, type of gear.

Their general form is a cylinder or disk. The teeth project radially, and

with these "straight-cut gears", the leading edges of the teeth are aligned

parallel to the axis of rotation. These gears can only mesh correctly if

they are fitted to parallel axles.[2]

Helical gears

Intermeshing gears in motion

35

Unlike most gears, an internal gear (shown here) does not cause

direction reversal.

Helical gears from a Meccano construction set.

Helical gears offer a refinement over spur gears. The leading edges of

the teeth are not parallel to the axis of rotation, but are set at an angle.

Since the gear is curved, this angling causes the tooth shape to be a

segment of a helix. The angled teeth engage more gradually than do

spur gear teeth. This causes helical gears to run more smoothly and

quietly than spur gears. Helical gears also offer the possibility of using

non-parallel shafts. A pair of helical gears can be meshed in two ways:

with shafts oriented at either the sum or the difference of the helix

angles of the gears. These configurations are referred to as parallel or

crossed, respectively. The parallel configuration is the more

mechanically sound. In it, the helices of a pair of meshing teeth meet at

a common tangent, and the contact between the tooth surfaces will,

generally, be a curve extending some distance across their face widths.

In the crossed configuration, the helices do not meet tangentially, and

only point contact is achieved between tooth surfaces. Because of the

36

small area of contact, crossed helical gears can only be used with light

loads.

Quite commonly, helical gears come in pairs where the helix angle of

one is the negative of the helix angle of the other; such a pair might also

be referred to as having a right handed helix and a left handed helix of

equal angles. If such a pair is meshed in the 'parallel' mode, the two

equal but opposite angles add to zero: the angle between shafts is zero --

that is, the shafts are parallel. If the pair is meshed in the 'crossed'

mode, the angle between shafts will be twice the absolute value of either

helix angle.

Note that 'parallel' helical gears need not have parallel shafts -- this only

occurs if their helix angles are equal but opposite. The 'parallel' in

'parallel helical gears' must refer, if anything, to the (quasi) parallelism

of the teeth, not to the shaft orientation.

As mentioned at the start of this section, helical gears operate more

smoothly than do spur gears. With parallel helical gears, each pair of

teeth first make contact at a single point at one side of the gear wheel; a

moving curve of contact then grows gradually across the tooth face. It

may span the entire width of the tooth for a time. Finally, it recedes

until the teeth break contact at a single point on the opposite side of the

wheel. Thus force is taken up and released gradually. With spur gears,

the situation is quite different. When a pair of teeth meet, they

immediately make line contact across their entire width. This causes

impact stress and noise. Spur gears make a characteristic whine at high

speeds and can not take as much torque as helical gears because their

37

teeth are receiving impact blows. Whereas spur gears are used for low

speed applications and those situations where noise control is not a

problem, the use of helical gears is indicated when the application

involves high speeds, large power transmission, or where noise

abatement is important. The speed is considered to be high when the

pitch line velocity (that is, the circumferential velocity) exceeds 5000

ft/min.[3] A disadvantage of helical gears is a resultant thrust along the

axis of the gear, which needs to be accommodated by appropriate thrust

bearings, and a greater degree of sliding friction between the meshing

teeth, often addressed with specific additives in the lubricant.

[edit] Double helical gears

Double helical gears, invented by André Citroën and also known as

herringbone gears, overcome the problem of axial thrust presented by

'single' helical gears by having teeth that set in a 'V' shape. Each gear in

a double helical gear can be thought of as two standard, but mirror

image, helical gears stacked. This cancels out the thrust since each half

of the gear thrusts in the opposite direction. They can be directly

interchanged with spur gears without any need for different bearings.

Where the oppositely angled teeth meet in the middle of a herringbone

gear, the alignment may be such that tooth tip meets tooth tip, or the

alignment may be staggered, so that tooth tip meets tooth trough. The

latter type of alignment results in what is known as a Wuest type

herringbone gear.

38

With the older method of fabrication, herringbone gears had a central

channel separating the two oppositely-angled courses of teeth. This was

necessary to permit the shaving tool to run out of the groove. The

development of the Sykes gear shaper now makes it possible to have

continuous teeth, with no central gap.

Bevel gears

Bevel gear used to lift floodgate by means of central screw.

Main article: Bevel gear

Bevel gears are essentially conically shaped, although the actual gear

does not extend all the way to the vertex (tip) of the cone that bounds it.

With two bevel gears in mesh, the vertices of their two cones lie on a

single point, and the shaft axes also intersect at that point. The angle

between the shafts can be anything except zero or 180 degrees. Bevel

gears with equal numbers of teeth and shaft axes at 90 degrees are

called miter gears.

The teeth of a bevel gear may be straight-cut as with spur gears, or they

may be cut in a variety of other shapes. 'Spiral bevel gears' have teeth

that are both curved along their (the tooth's) length; and set at an angle,

analogously to the way helical gear teeth are set at an angle compared to

spur gear teeth. 'Zero bevel gears' have teeth which are curved along

39

their length, but not angled. Spiral bevel gears have the same

advantages and disadvantages relative to their straight-cut cousins as

helical gears do to spur gears. Straight bevel gears are generally used

only at speeds below 5 m/s (1000 ft/min), or, for small gears, 1000 r.p.m.[4]

Crown gear

A crown gear

A crown gear or contrate gear is a particular form of bevel gear whose

teeth project at right angles to the plane of the wheel; in their

orientation the teeth resemble the points on a crown. A crown gear can

only mesh accurately with another bevel gear, although crown gears are

sometimes seen meshing with spur gears. A crown gear is also

sometimes meshed with an escapement such as found in mechanical

clocks.

[edit] Hypoid gears

Main article: Hypoid

Hypoid gears resemble spiral bevel gears, except that the shaft axes are

offset, not intersecting. The pitch surfaces appear conical but, to

compensate for the offset shaft, are in fact hyperboloids of revolution.[citation needed] Hypoid gears are almost always designed to operate with

shafts at 90 degrees. Depending on which side the shaft is offset to,

relative to the angling of the teeth, contact between hypoid gear teeth

may be even smoother and more gradual than with spiral bevel gear

40

teeth. Also, the pinion can be designed with fewer teeth than a spiral

bevel pinion, with the result that gear ratios of 60:1 and higher are

"entirely feasible" using a single set of hypoid gears.[5]

Worm gear

A worm and gear from a Meccano construction set

Main article: Worm gear

A worm is a gear that resembles a screw. It is a species of helical gear,

but its helix angle is usually somewhat large(ie., somewhat close to 90

degrees) and its body is usually fairly long in the axial direction; and it

is these attributes which give it its screw like qualities. A worm is

usually meshed with an ordinary looking, disk-shaped gear, which is

called the "gear", the "wheel", the "worm gear", or the "worm wheel".

The prime feature of a worm-and-gear set is that it allows the

attainment of a high gear ratio with few parts, in a small space. Helical

gears are, in practice, limited to gear ratios of 10:1 and under; worm

gear sets commonly have gear ratios between 10:1 and 100:1, and

occasionally 500:1.[6] In worm-and-gear sets, where the worm's helix

angle is large, the sliding action between teeth can be considerable, and

41

the resulting frictional loss causes the efficiency of the drive to be

usually less than 90 percent, sometimes less than 50 percent, which is far

less than other types of gears.

The distinction between a worm and a helical gear is made when at least

one tooth persists for a full 360 degree turn around the helix. If this

occurs, it is a 'worm'; if not, it is a 'helical gear'. A worm may have as

few as one tooth. If that tooth persists for several turns around the helix,

the worm will appear, superficially, to have more than one tooth, but

what one in fact sees is the same tooth reappearing at intervals along the

length of the worm. The usual screw nomenclature applies: a one-

toothed worm is called "single thread" or "single start"; a worm with

more than one tooth is called "multiple thread" or "multiple start".

We should note that the helix angle of a worm is not usually specified.

Instead, the lead angle, which is equal to 90 degrees minus the helix

angle, is given.

In a worm-and-gear set, the worm can always drive the gear. However,

if the gear attempts to drive the worm, it may or may not succeed.

Particularly if the lead angle is small, the gear's teeth may simply lock

against the worm's teeth, because the force component circumferential

to the worm is not sufficient to overcome friction. Whether this will

happen depends on a function of several parameters; however, an

approximate rule is that if the tangent of the lead angle is greater than

the coefficient of friction, the gear will not lock.[8] Worm-and-gear sets

that do lock in the above manner are called "self locking". The self

locking feature can be an advantage, as for instance when it is desired to

42

set the position of a mechanism by turning the worm and then have the

mechanism hold that position. An example of this is the tuning

mechanism on some types of stringed instruments.

If the gear in a worm-and-gear set is an ordinary helical gear only point

contact between teeth will be achieved.[9] If medium to high power

transmission is desired, the tooth shape of the gear is modified to

achieve more intimate contact with the worm thread. A noticeable

feature of most such gears is that the tooth tops are concave, so that the

gear partly envelopes the worm. A further development is to make the

worm concave (viewed from the side, perpendicular to its axis) so that it

partly envelopes the gear as well; this is called a cone-drive or Hindley

worm.

Helical and Worm Hand,

A right hand helical gear or right hand worm is one in which the teeth

twist clockwise as they recede from an observer looking along the axis.

The designations, right hand and left hand, are the same as in the long

established practice for screw threads, both external and internal. Two

external helical gears operating on parallel axes must be of opposite

hand. An internal helical gear and its pinion must be of the same hand.

43

A left hand helical gear or left hand worm is one in which the teeth twist

counterclockwise as they recede from an observer looking along the

axis.[11]

Rack and pinion

Rack and pinion animation

Main article: Rack and pinion

A rack is a toothed bar or rod that can be thought of as a sector gear

with an infinitely large radius of curvature. Torque can be converted to

linear force by meshing a rack with a pinion: the pinion turns; the rack

moves in a straight line. Such a mechanism is used in automobiles to

convert the rotation of the steering wheel into the left-to-right motion of

the tie rod(s). Racks also feature in the theory of gear geometry, where,

for instance, the tooth shape of an interchangeable set of gears may be

specified for the rack (infinite radius), and the tooth shapes for gears of

particular actual radii then derived from that.

[edit] External vs. internal gears

An external gear is one with the teeth formed on the outer surface of a

cylinder or cone. Conversely, an internal gear is one with the teeth

44

formed on the inner surface of a cylinder or cone. For bevel gears, an

internal gear is one with the pitch angle exceeding 90 degrees.

Electronic Portion

CHAPTER – 5

POWER SUPPLY

DIAGRAM WITH FOUR DIODE

WORKING

All most all types of electronics circuit need a source of DC supply

for their operation. As that can be obtained by storage cell are very

expensive and convenient but have advantage of being portable and ripple

fraction however their current is low and voltage are low so they need

frequency replacement so to overcome this we have converted our AC 220V

to different less voltage output in our circuit we have use two types of

supplies. One is 6V and other is 12V. By using step-down transformer we

45

have step-down double AC and by using two diodes we have converted AC

into DC. And filtering by 10000uF capacitor. We have regulator it by

regulator IC and thus taking O/P regulated DC supply for 12V. We have use

7812 regulating IC respectively.

Receiver TSop

Photo Modules for PCM Remote Control SystemsAvailable types for different carrier frequenciesType fo Type foTSOP1730 30 kHz TSOP1733 33 kHzTSOP1736 36 kHz TSOP1737 36.7 kHzTSOP1738 38 kHz TSOP1740 40 kHzTSOP1756 56 kHz

DescriptionThe TSOP17.. – series are miniaturized receivers forinfrared remote control systems. PIN diode andpreamplifier are assembled on lead frame, the epoxypackage is designed as IR filter.

46

The demodulated output signal can directly bedecoded by a microprocessor. TSOP17.. is thestandard IR remote control receiver series, supportingall major transmission codes.94 8691GNDVS OUTFeatures_ Photo detector and preamplifier in one package_ Internal filter for PCM frequency_ Improved shielding against electrical fielddisturbance_ TTL and CMOS compatibility_ Output active low_ Low power consumption_ High immunity against ambient light_ Continuous data transmission possible(up to 2400 bps)_ Suitable burst length 10 cycles/burstBlock Diagram

TSOP17..Vishay TelefunkenRev. 10, 02-Apr-01www.vishay.com Document Number 820302 (7)Absolute Maximum Ratings

47

Basic CharacteristicsTamb = 25_C

Application Circuit

Suitable Data FormatThe circuit of the TSOP17.. is designed in that way thatunexpected output pulses due to noise or disturbancesignals are avoided. A bandpassfilter, an integratorstage and an automatic gain control are used tosuppress such disturbances.

48

The distinguishing mark between data signal anddisturbance signal are carrier frequency, burst lengthand duty cycle.The data signal should fullfill the following condition:Carrier frequency should be close to centerfrequency of the bandpass (e.g. 38kHz).Burst length should be 10 cycles/burst or longer.After each burst which is between 10 cycles and 70cycles a gap time of at least 14 cycles is neccessary.For each burst which is longer than 1.8ms acorresponding gap time is necessary at some time inthe data stream. This gap time should have at leastsame length as the burst.Up to 1400 short bursts per second can be receivedcontinuously.Some examples for suitable data format are:NEC Code, Toshiba Micom Format, Sharp Code, RC5Code, RC6 Code, R–2000 Code, Sony Format(SIRCS).When a disturbance signal is applied to the TSOP17..it can still receive the data signal. However thesensitivity is reduced to that level that no unexpectedpulses will occure.Some examples for such disturbance signals whichare suppressed by the TSOP17.. are:DC light (e.g. from tungsten bulb or sunlight)Continuous signal at 38kHz or at any otherfrequencySignals from fluorescent lamps with electronicballast (an example of the signal modulation is in thefigure below).0 5 10 15 20time [ms]IR Signal from Fluorescent Lamp with low Modulation

49

CHAPTER – 6

MICROCONTROLLER

WELCOME TO THE WORLD OF THE MICROCONTROLLERS.

Look around. Notice the smart “intelligent” systems? Be it the T.V, washing machines, video games, telephones, automobiles, aero planes, power systems, or any application having a LED or a LCD as a user interface, the control is likely to be in the hands of a micro controller!

Measure and control, that’s where the micro controller is at its best.

Micro controllers are here to stay. Going by the current trend, it is obvious that micro controllers will be playing bigger and bigger roles in the different activities of our lives.

These embedded chips are very small, but are designed to replace components much bigger and bulky In size. They process information very intelligently and efficiently. They sense the environment around them. The signals they gather are tuned into digital data that streams through tributaries of circuit lines at the speed of light. Inside the microprocessor collates and calculators. The software has middling intelligence. Then in a split second, the processed streams are shoved out.

What is the primary difference between a microprocessor and a micro controller?

Unlike the microprocessor, the micro controller can be considered to be a true “Computer on a chip”.

In addition to the various features like the ALU, PC, SP and registers found on a microprocessor, the micro controller also incorporates features like the ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc.

50

While the microprocessor is more a general-purpose device, used for read, write and calculations on data, the micro controller, in addition to the above functions also controls the environment.

89S52 micro controller

The 89S52

The 89S52 developed and launched in the early 80`s, is one of the most popular micro controller in use today. It has a reasonably large amount of built in ROM and RAM. In addition it has the ability to access external memory.

The generic term `8x51` is used to define the device. The value of x defining the kind of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7, indicates EPROM and x=9 indicates EEPROM or Flash.

A note on ROM

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The early 89S52, namely the 8031 was designed without any ROM. This device could run only with external memory connected to it. Subsequent developments lead to the development of the PROM or the programmable ROM. This type had the disadvantage of being highly unreliable.

The next in line, was the EPROM or Erasable Programmable ROM. These devices used ultraviolet light erasable memory cells. Thus a program could be loaded, tested and erased using ultra violet rays. A new program could then be loaded again.

An improved EPROM was the EEPROM or the electrically erasable PROM. This does not require ultra violet rays, and memory can be cleared using circuits within the chip itself.

Finally there is the FLASH, which is an improvement over the EEPROM. While the terms EEPROM and flash are sometimes used interchangeably, the difference lies in the fact that flash erases the complete memory at one stroke, and not act on the individual cells. This results in reducing the time for erasure.

Different microcontrollers in market.

PIC One of the famous microcontrollers used in the industries. It is based on RISC Architecture which makes the microcontroller process faster than other microcontroller.

INTEL These are the first to manufacture microcontrollers. These are not as sophisticated other microcontrollers but still the easiest one to learn.

ATMEL Atmel’s AVR microcontrollers are one of the most powerful in the embedded industry. This is the only microcontroller having 1kb of ram even the entry stage. But it is unfortunate that in India we are unable to find this kind of microcontroller.

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Intel 89S52

Intel 89S52 is CISC architecture which is easy to program in assembly language and also has a good support for High level languages.

The memory of the microcontroller can be extended up to 68K.

This microcontroller is one of the easiest microcontrollers to learn.

The 89S52 microcontroller is in the field for more than 20 years. There are lots of books and study materials are readily available for 89S52.

Derivatives

The best thing done by Intel is to give the designs of the 89S52 microcontroller to everyone. So it is not the fact that Intel is the only manufacture for the 89S52 there more than 20 manufactures, with each of minimum 20 models. Literally there are hundreds of models of 89S52 microcontroller available in market to choose. Some of the major manufactures of 89S52 are

Atmel

Philips

PhilipsThe Philips‘s 89S52 derivatives has more number of features than in any microcontroller. The costs of the Philips microcontrollers are higher than the Atmel’s which makes us to choose Atmel more often than Philips

53

DallasDallas has made many revolutions in the semiconductor market. Dallas’s 89S52 derivative is the fastest one in the market. It works 3 times as fast as a 89S52 can process. But we are unable to get more in India.

AtmelThese people were the one to master the flash devices. They are the cheapest microcontroller available in the market. Atmel’s even introduced a 20pin variant of 89S52 named 2051. The Atmel’s 89S52 derivatives can be got in India less than 70 rupees. There are lots of cheap programmers available in India for Atmel. So it is always good for students to stick with 89S52 when you learn a new microcontroller.

The 89S52 doesn’t have any special feature than other microcontroller. The only feature is that it is easy to learn. Architecture makes us to know about the hardware features of the microcontroller. The features of the 89S52 are

8K Bytes of Flash Memory 256 x 8-Bit Internal RAM Fully Static Operation: 1 MHz to 24 MHz 32 Programmable I/O Lines Two 16-Bit Timer/Counters Six Interrupt Sources (5 Vectored) Programmable Serial Channel Low Power Idle and Power Down Modes

The 89S52 has a 8-Bit CPU that means it is able to process 8 bit of data at a time. 89S52 has 235 instructions. Some of the important registers and their functions are

Let’s now move on to a practical example. We shall work on a simple

practical application and using the example as a base, shall explore the

various features of the 89S52 microcontroller.

54

Consider an electric circuit as follows,

The positive side (+ve) of the battery is connected to one side of a switch. The other side of the switch is connected to a bulb or LED (Light Emitting Diode). The bulb is then connected to a resistor, and the other end of the resistor is connected to the negative (-ve) side of the battery.

When the switch is closed or ‘switched on’ the bulb glows. When the switch is open or ‘switched off’ the bulb goes off

If you are instructed to put the switch on and off every 30 seconds, how would you do it? Obviously you would keep looking at your watch and every time the second hand crosses 30 seconds you would keep turning the switch on and off.

Imagine if you had to do this action consistently for a full day. Do you think you would be able to do it? Now if you had to do this for a month, a year??

No way, you would say!

The next step would be, then to make it automatic. This is where we use the Microcontroller.

But if the action has to take place every 30 seconds, how will the microcontroller keep track of time?

Execution time

Look at the following instruction, clr p1.0

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This is an assembly language instruction. It means we are instructing the microcontroller to put a value of ‘zero’ in bit zero of port one. This instruction is equivalent to telling the microcontroller to switch on the bulb. The instruction then to instruct the microcontroller to switch off the bulb is,

Set p1.0

This instructs the microcontroller to put a value of ‘one’ in bit zero of port one.

Don’t worry about what bit zero and port one means. We shall learn it in more detail as we proceed.

There are a set of well defined instructions, which are used while communicating with the microcontroller. Each of these instructions requires a standard number of cycles to execute. The cycle could be one or more in number.

How is this time then calculated?

The speed with which a microcontroller executes instructions is determined by what is known as the crystal speed. A crystal is a component connected externally to the microcontroller. The crystal has different values, and some of the used values are 6MHZ, 10MHZ, and 11.059 MHz etc.Thus a 10MHZ crystal would pulse at the rate of 10,000,000 times per second.

The time is calculated using the formula

No of cycles per second = Crystal frequency in HZ / 12.

For a 10MHZ crystal the number of cycles would be,

10,000,000/12=833333.33333 cycles.

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This means that in one second, the microcontroller would execute 833333.33333 cycles.

Therefore for one cycle, what would be the time? Try it out.

The instruction clr p1.0 would use one cycle to execute. Similarly, the instruction setb p1.0 also uses one cycle.

So go ahead and calculate what would be the number of cycles required to be executed to get a time of 30 seconds!

Getting back to our bulb example, all we would need to do is to instruct the microcontroller to carry out some instructions equivalent to a period of 30 seconds, like counting from zero upwards, then switch on the bulb, carry out instructions equivalent to 30 seconds and switch off the bulb.

Just put the whole thing in a loop, and you have a never ending on-off sequence.

Let us now have a look at the features of the 89S52 core, keeping the above example as a reference,

1. 8-bit CPU.( Consisting of the ‘A’ and ‘B’ registers)

Most of the transactions within the microcontroller are carried out through the ‘A’ register, also known as the Accumulator. In addition all arithmetic functions are carried out generally in the ‘A’ register. There is another register known as the ‘B’ register, which is used exclusively for multiplication and division.

Thus an 8-bit notation would indicate that the maximum value that can be input into these registers is ‘11111111’. Puzzled?

The value is not decimal 111, 11,111! It represents a binary number, having an equivalent value of ‘FF’ in Hexadecimal and a value of 255 in decimal.

We shall read in more detail on the different numbering systems namely the Binary and Hexadecimal system in our next module.

57

2. 8K on-chip ROM

Once you have written out the instructions for the microcontroller, where do you put these instructions?

Obviously you would like these instructions to be safe, and not get deleted or changed during execution. Hence you would load it into the ‘ROM’

The size of the program you write is bound to vary depending on the application, and the number of lines. The 89S52 microcontroller gives you space to load up to 8K of program size into the internal ROM.

8K, that’s all? Well just wait. You would be surprised at the amount of stuff you can load in this 8K of space.

Of course you could always extend the space by connecting to 68K of external ROM if required.

3. 256 bytes on-chip RAM

This is the space provided for executing the program in terms of moving data, storing data etc.

4. 32 I/O lines. (Four- 8 bit ports, labeled P0, P1, P2, P3)

In our bulb example, we used the notation p1.0. This means bit zero of port one. One bit controls one bulb.

Thus port one would have 8 bits. There are a total of four ports named p0, p1, p2, p3, giving a total of 32 lines. These lines can be used both as input or output.

5. Two 16 bit timers / counters.

A microcontroller normally executes one instruction at a time. However certain applications would require that some event has to be tracked independent of the main program.

The manufacturers have provided a solution, by providing two timers. These

58

timers execute in the background independent of the main program. Once the required time has been reached, (remember the time calculations described above?), they can trigger a branch in the main program.

These timers can also be used as counters, so that they can count the number of events, and on reaching the required count, can cause a branch in the main program.

6. Full Duplex serial data receiver / transmitter.

The 89S52 microcontroller is capable of communicating with external devices like the PC etc. Here data is sent in the form of bytes, at predefined speeds, also known as baud rates.

The transmission is serial, in the sense, one bit at a time

7. 5- interrupt sources with two priority levels (Two external and three internal)

During the discussion on the timers, we had indicated that the timers can trigger a branch in the main program. However, what would we do in case we would like the microcontroller to take the branch, and then return back to the main program, without having to constantly check whether the required time / count has been reached?

This is where the interrupts come into play. These can be set to either the timers, or to some external events. Whenever the background program has reached the required criteria in terms of time or count or an external event, the branch is taken, and on completion of the branch, the control returns to the main program.

Priority levels indicate which interrupt is more important, and needs to be executed first in case two interrupts occur at the same time.

8. On-chip clock oscillator.

This represents the oscillator circuits within the microcontroller. Thus the hardware is reduced to just simply connecting an external crystal, to achieve the required pulsing rate.

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DescriptionThe AT89S52 is a low-power, high-performance CMOS 8-bit microcomputer with 4Kbytes of Flash programmable and erasable read only memory (PEROM). The deviceis manufactured using Atmel’s high-density nonvolatile memory technology and iscompatible with the industry-standard MCS-51 instruction set and pinout. The on-chipFlash allows the program memory to be reprogrammed in-system or by a conventionalnonvolatile memory programmer. By combining a versatile 8-bit CPU with Flashon a monolithic chip, the Atmel AT89S52 is a powerful microcomputer which providesa highly-flexible and cost-effective solution to many embedded control applications.Features• Compatible with MCS-51™ Products• 4K Bytes of In-System Reprogrammable Flash Memory– Endurance: 1,000 Write/Erase Cycles• Fully Static Operation: 0 Hz to 24 MHz• Three-level Program Memory Lock• 128 x 8-bit Internal RAM• 32 Programmable I/O Lines• Two 16-bit Timer/Counters• Six Interrupt Sources• Programmable Serial Channel• Low-power Idle and Power-down Modes

PIN Diagram of 89S52

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Pin DescriptionVCCSupply voltage.GNDGround.Port 0Port 0 is an 8-bit open-drain bi-directional I/O port. As anoutput port, each pin can sink eight TTL inputs. When 1sare written to port 0 pins, the pins can be used as high impedanceinputs.Port 0 may also be configured to be the multiplexed low orderaddress/data bus during accesses to external programand data memory. In this mode P0 has internalpullups.Port 0 also receives the code bytes during Flash programming,and outputs the code bytes during programverification. External pullups are required during programverification.Port 1Port 1 is an 8-bit bi-directional I/O port with internal pull-ups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins they are pulled high bythe internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pullups.Port 1 also receives the low-order address bytes duringFlash programming and verification.Port 2Port 2 is an 8-bit bi-directional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.When 1s are written to Port 2 pins they are pulled high bythe internal pullups and can bPort 2 pins that are externally being pulled low will sourcecurrent (IIL) because of the internal pullups.Port 2 emits the high-order address byte during fetchesfrom external program memory and during accesses toexternal data memory that use 16-bit addresses (MOVX @DPTR). In this application, it uses strong internal pullupswhen emitting 1s. During accesses to external data memorythat use 8-bit addresses (MOVX @ RI), Port 2 emits the

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contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and somecontrol signals during Flash programming and verification.Port 3Port 3 is an 8-bit bi-directional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs.When 1s are written to Port 3 pins they are pulled high bythe internal pullups and can be used as inputs. As inputs,Port 3 pins that are externally being pulled low will sourcecurrent (IIL) because of the pullups.Port 3 also serves the functions of various special featuresof the AT89S52 as listed below:Port Pin Alternate FunctionsP3.0 RXD (serial input port)P3.1 TXD (serial output port)P3.2 INT0 (external interrupt 0)P3.3 INT1 (external interrupt 1)P3.4 T0 (timer 0 external input)P3.5 T1 (timer 1 external input)P3.6 WR (external data memory write strobe)P3.7 RD (external data memory read strobe)Port 3 also receives some control signals for Flash programmingand verification.RSTReset input. A high on this pin for two machine cycles whilethe oscillator is running resets the device.ALE/PROGAddress Latch Enable output pulse for latching the low byteof the address during accesses to external memory. Thispin is also the program pulse input (PROG) during Flashprogramming.In normal operation ALE is emitted at a constant rate of 1/6the oscillator frequency, and may be used for external timingor clocking purposes. Note, however, pulse is skipped during each access to external DataMemory.If desired, ALE operation can be disabled by setting bit 0 ofSFR location 8EH. With the bit set, ALE is active only duringa MOVX or MOVC instruction. Otherwise, the pin isweakly pulled high. Setting the ALE-disable bit has no

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effect if the microcontroller is in external execution mode.PSENProgram Store Enable is the read strobe to external programmemory.When the AT89S52 is executing code from external programmemory, PSEN is activated twice each machinecycle, except that two PSEN activations are skipped duringeach access to external data memory.EA/VPPExternal Access Enable. EA must be strapped to GND inorder to enable the device to fetch code from external programmemory locations starting at 0000H up to FFFFH.Note, however, that if lock bit 1 is programmed, EA will beinternally latched on reset.EA should be strapped to VCC for internal programexecutions.This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming, for parts that require12-volt VPP.XTAL1Input to the inverting oscillator amplifier and input to theinternal clock operating circuit.XTAL2Output from the inverting oscillator amplifier. that one ALEunconnected while XTAL1 is driven as shown in Figure 2.There are no requirements on the duty cycle of the externalclock signal, since the input to the internal clocking circuitryis through a divide-by-two flip-flop, but minimum and maximumvoltage high and low time specifications must be observed

CHAPTER – 7

Motor Drive Circuit

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Working :-

In this we use two optocouplers and four transistors ( two NPN and Two PNP). Circuit of transistor is known as H- Bridge circuit.

Optocoupler:-

Pin No. 1 of both ICs are connected with positive supply and Pin No. 2 of both ICs are connrcted with the output of Microcontroller. Pin no. 4 of ICs are connected with supply throught a 470 ohm resistance and Pin No. 3 is grounded. Pin No. 1 & 2 contains LED and Pin No. 3 & 4 Contain receiver for detecting the light of LED and it works as a Transistors.

H-Bridge Circuit:-

We use two npn and two pnp diodes. Collector of pnp diodes are connected with negative supply and collector of npn diodes are connected with positive supply. Base of one npn and one pnp is connected with the pin no. 4 of 1st optocoupler through a 1 K resistance. Base of other transistor are connected

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with the pin 4 of 2nd IC. Now emitter of one pair of different transistors are connected with one terminal of motor and 2nd terminal of motor is connected with other transisitor’s emitter.

Working:-

Inb the normal condition microcontroller gives the high output to pin no. 2 of both ICs and pin no. 1 is already connected with positive supply so both LEDs will not work hence voltage on both pairs of transistors will be high. Due high on both pair H-Bridge circuit will not work. Now one IR sensor will ground the input of Microcontroller hence one pin of microcontroller goes to low at output. So due to this pin no.2 of one IC will go to low and one high. Low pin of one IC glow the LED hence receiver of one IC will hence it will ground the positive supply so voltage at the base of one pair transistor will be low.So for low voltage one pnp transistor will work and gives the low voltage to motor at one point and at this time for high voltage at the other pair npn transistor will work and it gives the high voltage to motor at 2nd point so mpotor will rotate in one direction.

In 2nd condition 2nd IR sensor will work hence pin no 2 of second IC becomes low and of 1st Ic becomes high. So second IC will work like first IC and First Ic will Work like second IC which was in First condition. So due to this voltage polarity at the both pairs of base of all Tarnsistors gets changes and other left transistor will work. So they will change the polarity of motor hence motor will rotate and opposite direction.

Reset Circuitry:

As soon as you give the power supply the 8051 doesn’t start. You need to

restart for the microcontroller to start. Restarting the microcontroller is

nothing but giving a Logic 1 to the reset pin at least for the 2 clock pulses.

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So it is good to go for a small circuit which can provide the 2 clock pulses as

soon as the microcontroller is powered.

This is not a big circuit we are just using a capacitor to charge the

microcontroller and again discharging via resistor.

Crystals

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Crystals provide the synchronization of the internal function and to the

peripherals. Whenever ever we are using crystals we need to put the

capacitor behind it to make it free from noises. It is good to go for a 33pf

capacitor.

We can also resonators instead of costly crystal which are low cost and

external capacitor can be avoided.

But the frequency of the resonators varies a lot. And it is strictly not advised

when used for communications projects.

Using Keil C.

There is nothing much different from the Turbo C we used and Keil C we

are going to use. The only difference is that we need to change the header

file of the microcontroller we are going to use.

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Here in the above code I was using At89c51 so I am including this file for

compiling.

After including the file we must declare main function and start writing the

code.

DC Motor

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#include<AT89x51.h>

#include<AT89x51.h>void main(){int i;while(1){for (i = 0;i< 9000;i++)P1_1=0;for (i = 0;i< 9000;i++)P1_1=1;}}

These are the motors that are commonly found in the toys and the tape

recorders. These motors change the direction of rotation by changing the

polarity. Most chips can't pass enough current or voltage to spin a motor.

Also, motors tend to be electrically noisy (spikes) and can slam power back

into the control lines when the motor direction or speed is changed.

Specialized circuits (motor drivers) have been developed to supply motors

with power and to isolate the other ICs from electrical problems. These

circuits can be designed such that they can be completely separate boards,

reusable from project to project.

A very popular circuit for driving DC motors (ordinary or gearhead) is

called an H-bridge. It's called that because it looks like the capital letter 'H'

on classic schematics. The great ability of an H-bridge circuit is that the

motor can be driven forward or backward at any speed, optionally using a

completely independent power source.

The H-Bridge Circuit

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This circuit known as the H-bridge (named for its topological similarity to

the letter "H") is commonly used to drive motors. In this circuit two of four

transistors are selectively enabled to control current flow through a motor.

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opposite pair of transistors (Transistor One and Transistor Three) is enabled,

allowing current to flow through the motor. The other pair is disabled, and

can be thought of as out of the circuit.

By determining which pair of transistors is enabled, current can be made to

flow in either of the two directions through the motor. Because permanent-

magnet motors reverse their direction of turn when the current flow is

reversed, this circuit allows bidirectional control of the motor.

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The H-Bridge with Enable Circuitry

It should be clear that one would never want to enable Transistors One and

Two or Transistors Three and Four simultaneously. This would cause

current to flow from Power + to Power - through the transistors, and not the

motors, at the maximum current-handling capacity of either the power

supply or the transistors. This usually results in failure of the H-Bridge. To

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prevent the possibility of this failure, enable circuitry as depicted in Figure is

typically used.

In this circuit, the internal inverters ensure that the vertical pairs of

transistors are never enabled simultaneously. The Enable  input determines

whether or not the whole circuit is operational. If this input is false, then

none of the transistors are enabled, and the motor is free to coast to a stop.

By turning on the Enable input and controlling the two Direction inputs, the

motor can be made to turn in either direction.

Note that if both direction inputs are the same state (either true or false) and

the circuit is enabled, both terminals will be brought to the same voltage

(Power + or Power - , respectively). This operation will actively brake the

motor, due to a property of motors known as back emf, in which a motor that

is turning generates a voltage counter to its rotation. When both terminals of

the motor are brought to the same electrical potential, the back emf causes

resistance to the motor's rotation.

Stepper motors

Stepper motors are special kind of heavy duty motors having 2 or 4 coils.

The motors will be stepping each time when it get the pulse. As there are

many coils in the motors we need to energize the coils in a specific sequence

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for the rotation of the motor. These motors are mostly used in heavy

machines. The figure shown below consists of a 4 coil stepper motor and the

arrow mark will rotate when the coils are energized in the sequence.

Unlike DC motors stepper motors can be turned accurately for the given

degrees.

Servo motors

Servo motors unlike the stepper motor it has to be controlled by the timing

signal. This motor has only one coil. It is mostly used in train s for its

lightweight and low power consumption. The servo motors can also be

accurately rotated by the making the control signal of the servo motor high

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for a specific time period. Actually the servo motor will be having 3 wires

where 2 are for power supply and another one is for the control signal.

Driving the servomotors is so simple that you need to make the control

signal high for the specific amount of time. The width of the pulse

determines the output position of the shaft

Object Detection

Detecting objects without whiskers doesn’t require anything as sophisticated

as machine vision. Some train s use RADAR or SONAR (sometimes called

SODAR when used in air instead of water). An even simpler system is to

use infrared light to illuminate the train ’s path and determine when the light

reflects off an object.The IR illuminators and detectors are readily available

and inexpensive.

Infrared As Headlights

The infrared object detection system we’ll build on the Bot is like a car’s

headlights in several respects. When the light from a car’s headlights reflects

off obstacles, your eyes detect the obstacles and your brain processes them

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and makes your body guide the car accordingly. We will be using infrared

LEDs for headlights. They emit infrared, and in some cases, the infrared

reflects off objects and bounces back in the direction of the detecter. The

eyes of the Bot( mobile) are the infrared detectors. The infrared detectors

send signals to the Microcontroller indicating whether or not they detect

infrared reflected off an object. The brain of the Bot, the microcontroller

makes decisions and operates the motors based on this sensor input.

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CHAPTER - 9

CIRCUIT DIAGRAM

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WORKING

First of all we give a 12 volt supply to the train then power supply circuit

will convert it in 5 volt which is required for microcontroller and all parts of

circuit. this supply goes to microcontroller. Positive voltage at 40 no. pin

and 20 no. is connected with Ground. We give a 5 volt supply at pin no. 9

for reset purpose through a reset circuit. Reset circuit is constructed by 10uF

capacitor and 10 K resistance. Pin no, 18 and 19 is connected with 12 Mhz

crystal oscillator and 2 ceramic capacitor respected the ground. Now we use

a TSOP 1738 of which pin no. 1 is connected with GND and 2nd pin is

connected with Positive 5 volt. It gives output at pin no. 3 which is

connected with P3.3 which receives the data in serial form. After this

programming works and gives output at port 2. Port 2 is connected with

motor circuit. One motor circuit is connected with P2.0 and P2.1 and second

motor is connected with P2.2 and P2.3. for forward direction MCU gives

low at P2.0 and P2.2 and high at other two pins. Due to this both motors will

rotate in same direction. To understand this functioning of motors above

working of motor circuit is descrived. For reverse direction P2.1 and P2.3

goes low and respectively P2.0 and P2.2 goes high so both motors will rotate

same but in different direction as that of previous direction. For left or right

turning of train we give low signal at Pin no. P2.0 and P2.3 or P2.1 and

P2.2. due to this both motors will rotate in opposite direction hence train

will turn in one direction.

To control the function of stop we use IR transmitter and receiver at front

of Train. IR transmitter is connected with 5 volt supply through a 100 ohm

resitance permanently. IR receiver used as a switching circuit for

microcontroller. First of all we provide 5 volt supply at P1.0 through 10 k

resistor and also we connect IR reciver at this pin without any resistance. So

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when receiver detect the rays ( which are reflected by other train In the front

of main train) provide low signal to the microcontroller. So its starts its

programming working and provide high signal at all pins of motor circuit

and that happen motor get stop.

To movement of this train we use wheels direct with motor or in some

situations gears are used with motor and wheel to create torque and speed of

train .

Programming

/

*************************************************************

********ir train new modified

*************************************************************

*********/

VAR1 equ r7 ;Temporary Variable

TEMP equ 10H ;Temp variable

COUNT equ 11H ;Count

ADDR equ 12H ;Device address

CMD equ 13H ;Command

FLIP bit 00H ;Flip bit

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TOG bit 01H ;Temp bit for flip

IR equ P3.3 ;IR Receiver connected to this pin

SW1 equ P2.0 ;Switch 1 connected here

SW2 equ P2.1 ;Switch 2 connected here

SW3 equ P2.2 ;Switch 3 connected here

SW4 equ P2.3 ;Switch 4 connected here

SW5 equ P2.4 ;Switch 5 connected here

SW6 equ P2.5 ;Switch 6 connected here

SW7 equ P2.6 ;Switch 7 connected here

SW8 equ P2.7 ;Switch 8 connected here

SWport equ P1 ;Port at which switches are connected

org 00H ;Start of prog

main:

nop

fcmd:

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nvalid:

ljmp main

valid: ;Key press check

clr a

mov c,FLIP

rlc a

mov TEMP,a

clr a

mov c,TOG

rlc a

cjne a,TEMP,valid1

sjmp nvalid

valid1:

mov c,FLIP

mov TOG,c

mov a,CMD

clr c

cjne a,#1,skip1 ;Check for SW1

acall moto1

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ljmp main

isset1:

clr SW1

ljmp main

moto1:

clr p2.0

setb p2.1

clr p2.2

setb p2.3

acall delay

acall delay

setb p2.0

setb p2.1

setb p2.2

setb p2.3

ret

skip1:

cjne a,#2,skip2 ;Check for SW2

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acall moto2

ljmp main

isset2:

clr SW2

ljmp main

moto2:

setb p2.0

clr p2.1

setb p2.2

clr p2.3

acall delay

acall delay

setb p2.0

setb p2.1

setb p2.2

setb p2.3

ret

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skip2:

cjne a,#3,skip3 ;Check for SW3

acall moto3

ljmp main

isset3:

clr SW3

ljmp main

moto3:

clr p2.0

setb p2.1

setb p2.2

clr p2.3

acall delay

acall delay

setb p2.0

setb p2.1

setb p2.2

setb p2.3

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ret

skip3:

cjne a,#4,skip4 ;Check for SW4

acall moto4

ljmp main

isset4:

clr SW4

ljmp main

moto4:

setb p2.0

clr p2.1

clr p2.2

setb p2.3

acall delay

acall delay

setb p2.2

setb p2.3

setb p2.0

setb p2.1

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ret

skip4:

cjne a,#5,skip5 ;Check for SW5

acall moto5

ljmp main

isset5:

clr SW5

ljmp main

moto5:

setb p2.4

clr p2.5

acall delay

setb p2.4

setb p2.5

ret

skip5:

cjne a,#6,skip6 ;Check for SW6

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acall moto6

ljmp main

isset6:

clr SW6

ljmp main

moto6:

clr p2.4

setb p2.5

acall delay

setb p2.4

setb p2.5

ret

skip6:

cjne a,#7,skip7 ;Check for SW7

jb SW7,isset7

setb SW7

ljmp main

isset7:

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clr SW7

ljmp main

skip7:

cjne a,#8,skip8 ;Check for SW8

jb SW8,isset8

setb SW8

ljmp main

isset8:

clr SW8

ljmp main

skip8:

cjne a,#0CH,exit ;Check for all switches

mov SWport,#00H

ljmp main

exit:

ljmp main

delay:

acall delay1

acall delay1

acall delay1

90

acall delay1

acall delay1

ret

delay1:

MOV R6,#255

AGAIN22: MOV R7,#255

BACK22: DJNZ R7,BACK22

DJNZ R6,AGAIN22

RET

END ;End of program

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CHAPTER – 10

ADVANTAGES

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CHAPTER – 11

DISADVANTAGES

CHAPTER – 12

APPLICATION

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CHAPTER – 13

PRECAUTIONS

1. According to circuit all the different components for their services,

ability.

2. During soldering on the PCB, one should be very careful regarding

short circuit, dry units, etc.

3. Components direction especially electrolytic capacitor, transistor,

must be kept in mind for their actual position.

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4. Put each and every component on the PCB according their actual

position.

5. Proper care must be taken by solders on transistor so that these are not

to be damaged due to leakage of current.

6. Put each and every component of the same value on the PCB as per

diagram.

Bibliography:

www.ludhianaprojects.com/train ics

http://www.sciencejoywagon.com/physicszone/lesson/otherpub/wfendt/electricmotor.htm

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