mini_doc

1.1 INTRODUCTION

TRAFFIC DENSITY ANALYZER CUM SIGNALING FOR METRO

CITIES is an application specific project which provides an intelligent environment.

The heart of our project is the microcontroller which will provide the controlling of

the traffic depending upon the density in each junction.

In this project we use IR communication to analyze traffic density. The IR

rays are continuously transmitted and received by the IR transmitter and IR receiver

respectively.

Whenever discontinuity occurs in the this process, the microcontroller senses

the result, compares it with all the four junctions and shows the green signal for

longer time period (where the traffic density is heavy) while the red signal is shown to

the other three roads.

1.2 AIM OF THE PROJECT

The main aim of the project is to reduce and in fact eliminate the traffic

density problems especially in metropolitan cities during busy hours.

The present day signaling process is a timed process i.e. the signaling of the

junctions is for same amount of time in all the four junctions irrespective of traffic

density. With this, the junction having more traffic is given green signal for the same

time which is being given to the junction having less traffic or no traffic. Thus the

density in one junction keeps on increasing while the other junction is clear with no

vehicles.

1.3 METHODOLOGY

In our project, we place IR transmitters and IR receivers in line of sight on

either sides of the road, where continuous transmission and reception of IR rays take

place. When there is any break up in the above process for specific period of time,

1

the microcontroller senses the heavy density and makes the green light(signaling

heavy density) glow for more amount of time and red light on other three roads thus

reducing heavy traffic density problem at the junction.

1.4 SIGNIFICANCE OF THE WORK

The significance of our project is to monitor the present day traffic by

analyzing the density and signaling the roads for varied amount of time depending

upon the density thereby reducing the traffic problems in the metropolitan cities

especially during the busy hours.

The application of our project is mainly to monitor and control the traffic

density at the junctions and can also be extended in monitoring the street light and can

also be applied for domestic purpose.

1.5 ORGANIZATION OF THE REPORT

The chapter 1 gives the brief introduction, aim and methodology of the project, Significance of the Work and organisation of the Report.

The chapter 2 gives the literature review, block diagram and the description of the project.

The chapter 3 gives the detailed description of the hardware components that are used in the project i.e., microcontroller, power supply and its components and the IR LEDs.

The chapter 4 gives the project circuitry (schematic) and its working principle.

The chapter 5 gives the results and conclusions that are achieved successfully by the end of the project.

2

2.1 LITERATURE REVIEW

The past traffic controlling system is a human based system wherein the traffic

at the junctions is monitored and controlled by traffic police which always results in

abnormal traffic conditions due to many reasons and sometimes may be because of

the inefficiency of the traffic police in controlling the traffic.

However with the development in technology the past traffic controlling

system is replaced now with a timed signaling system wherein the traffic police is

replaced with the automatic signaling system. The only disadvantage with this is it

gives signaling for constant fixed amount of time in all junctions irrespective of traffic

in that particular junction and with this the heavy traffic on one road goes on

increasing and even though there is no traffic on the other side the green light is

shown for the same amount of time as that on the heavy road.

We overcome this problem through our project where the signaling depends

on the density on the road i.e. the road having heavy traffic is given green light for

more amount of time when compared to remaining roads, thus reducing the traffic.

3

2.2 BLOCK DIAGRAM OF THE PROJECT

Fig.(2): Block Diagram of Project

2.3 BLOCK DIAGRAM DESCRIPTION

The main objective of this project is to control the traffic depending upon the

density. As there is much time wastage with the traffic lights which involves the time,

we are designing the new system which controls the traffic depending upon the

density.

Here we place IR transmitter and the IR receiver at both ends of the roads.

Whenever the vehicles pass in-between them the continuity will be lost. Hence the

microcontroller senses the density is high.

4

MICRO CONTROLLER

POWER SUPPLY

Signals from IR receivers from all directions

RED

GREEN

YELLOW

North side

RED

GREEN

YELLOW

South side

RED

GREEN

YELLOW

East side RED

GREEN

YELLOW

West side

IR Transmitter

signalsFrom all

directions

Then the microcontroller will be making the light (green) to be glow much

time at the junction where the traffic is high.

The same procedure will be followed in all the four junctions. The signaling

from the four junctions will be taken into consideration and depending upon the

density microcontroller will make the decision.

Hardware Components

Microcontroller

Power supply

IR transmitter

IR receiver

LEDs

Software Tools

Keil

Embedded C

Express PCB

5

3.1 MICROCONTROLLER3.1.1 INTRODUCTION

A Microcontroller consists of a powerful CPU tightly coupled with memory,

various I/O interfaces such as serial port, parallel port timer or counter, interrupt

controller, data acquisition interfaces-Analog to Digital converter, Digital to Analog

converter integrated on to a single silicon chip.

If a system is developed with a microprocessor, the designer has to go for

external memory such as RAM, ROM, EPROM and peripherals. But controller is

provided all these facilities on a single chip. Development of a Microcontroller

reduces PCB size and cost of design.

One of the major differences between a Microprocessor and a Microcontroller

is that a controller often deals with bits not bytes as in the real world application. Intel

has introduced a family of Microcontrollers called the MCS-51.

3.1.2 BLOCK DIAGRAM

Accumulator

Registers

Internal RAM

Stack Pointer

Timer / Counter

Internal ROM

I/O Port

Interrupt Circuits

Clock Circuits

I/O Port

Program Counter

Arithmetic and Logic Unit

6

Fig.(3): Block diagram of Microcontroller3.1.3 Features

• 4K bytes of In-System Programmable (ISP) flash memory

• 4.0V to 5.5V operating range

• Fully static operation: 0 Hz to 33 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

• Full duplex UART serial channel

• Low-power idle and power-down modes

3.1.4 Description

The AT89S51 is a low-power, high-performance CMOS 8-bit microcontroller

with 4K bytes of in-system programmable Flash memory. The device is manufactured

using Atmel’s high-density nonvolatile memory technology and is compatible with

the industry- standard 80C51 instruction set and pin out.

The on-chip Flash allows the program memory to be reprogrammed in-system

or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit

CPU with in-system programmable Flash on a monolithic chip, the Atmel AT89S51 is

a powerful microcontroller which provides a highly-flexible and cost-effective

solution to many embedded control applications.

7

Fig.(3.1): Microcontroller3.1.5 PIN DIAGRAM

Fig.(3.2): Pin Diagram of Microcontroller

8

3.1.6 PIN DESCRIPTION

VCC - Supply voltage

GND - Ground

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can

sink eight TTL inputs. When 1’s are written to port 0 pins, the pins can be used as high-

impedance inputs. Port 0 can also be configured to be the multiplexed low-order

address/data bus during access to external program and data memory. In this mode, P0 has

internal pull-ups. Port 0 also receives the code bytes during flash programming and outputs

the code bytes during program verification. External pull-ups are required during program

verification.

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups. The port 1

output buffers can sink/source four TTL inputs. When 1’s are written to port 1 pins,

they are pulled high by the internal pull-ups and can be used as inputs.

As inputs, port 1 pins that are externally being pulled low will source current

(IIL) because of the internal pull-ups. Port 1 also receives the low-order address bytes

during flash programming and verification.

Port 2





(IIL) because of the internal pull-ups. Port 2 also receives the high-order address bits

and some control signals during flash programming and verification.

Port 3

9





(IIL) because of the pull-ups. Port 3 receives some control signals for flash

programming and verification.

Port 3 also serves the functions of various special features of the AT89S51, as

shown in the following table.

Table(1) : Port 3 Pin Functions

RST

Reset input. A high on this pin for two machine cycles while the oscillator is

running resets the device.

ALE/PROG

Address Latch Enable (ALE) is an output pulse for latching the low byte of the

address during access to external memory. This pin is also the program pulse input

(PROG) during Flash programming.

10

In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator

frequency and may be used for external timing or clocking purposes. Note, however,

that one ALE pulse is skipped during each access to external data memory.

If desired, ALE operation can be disabled by setting bit 0 of SFR location

8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction.

Otherwise, the pin is weakly pulled high.

Setting the ALE-disable bit has no effect if the microcontroller is in external

execution mode.

PSEN

Program Store Enable (PSEN) is the read strobe to external program memory.

When the AT89S51 is executing code from external program memory, PSEN is

activated twice each machine cycle, except that two PSEN activations are skipped

during each access to external data memory.

EA/VPP

External Access Enable. EA must be strapped to GND in order to enable the

device to fetch code from external program memory locations starting at 0000H upto

FFFFH.

However, that if lock bit 1 is programmed, EA will be internally latched on

reset. EA should be strapped to VCC for internal program executions. This pin also

receives the 12-volt programming enable voltage (VPP) during Flash programming.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock

operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

11

3.2 POWER SUPPLY DESCRIPTION

The power supplies are designed to convert high voltage AC mains electricity

to a suitable low voltage supply for electronics circuits and other devices. A power

supply can by broken down into a series of blocks, each of which performs a particular

function. A DC power supply which maintains the output voltage constant irrespective

of AC mains fluctuations or load variations is known as “Regulated DC Power

Supply”

For example a 5V regulated power supply system as shown below:

Fig.(3.3): Components of a typical power supply

3.3 TRANSFORMER

A transformer is an electrical device which is used to convert electrical power

from one electrical circuit to another without any change in frequency.

12

Transformers convert AC electricity from one voltage to another with little

loss of power. Transformers work only with AC and this is one of the reasons why

mains electricity is AC. Step-up transformers increase the output voltage while step-

down transformers decrease the output voltage.

Most of the power supplies use a step-down transformer to reduce the

dangerous high mains voltage to a safer low voltage. The input coil is called the

primary and the output coil is called the secondary. There is no electrical connection

between the two coils, instead they are linked by an alternating magnetic field created

in the soft-iron core of the transformer. The two lines in the middle of the circuit

symbol represent the core.

Transformers waste very little power so the power out is (almost) equal to the

power in. Note that as voltage is stepped down, current is stepped up. The ratio of the

number of turns on each coil, called the turn’s ratio, determines the ratio of the

voltages.

A step-down transformer has a large number of turns on its primary (input)

coil which is connected to the high voltage mains supply and a small number of turns

on its secondary (output) coil to give a low output voltage.

Fig.(3.4): An Electrical Transformer

13

Turns ratio = Vp/ VS = Np/NS

Power Out= Power In

VS x IS=VP x IP

Vp = primary (input) voltage

Np = number of turns on primary coil

Ip = primary (input) current

3.4 RECTIFIER

A circuit which is used to convert ac to dc is known as RECTIFIER. The

process of conversion of ac to dc is called “rectification”.

3.4.1 TYPES OF RECTIFIERS

Half wave Rectifier

Full wave rectifier

1. Centre tap full wave rectifier

2. Bridge type full wave rectifier

Half-wave Rectifier

The Half wave rectifier is a circuit, which converts an ac voltage to dc voltage

When a diode is connected to a source of alternating voltage, it will be

alternately forward-biased, and then reverse-biased, during each cycle of the AC sine-

wave.

When a single diode is used in a rectifier circuit, current will flow through the

circuit only during one-half of the input voltage cycle. For this reason, this rectifier

circuit is called a half-wave rectifier.

Full-wave Rectifier

14

A Full Wave Rectifier is a circuit, which converts an ac voltage into a

pulsating dc voltage using both half cycles of the applied ac voltage. It uses two

diodes of which one conducts during one half cycle while the other conducts during

the other half cycle of the applied ac voltage.

Fig.(3.5): Centre tap full wave rectifier

Bridge Rectifier

A bridge rectifier makes use of four diodes in a bridge arrangement to achieve

full-wave rectification. This is a widely used configuration, both with individual

diodes wired as shown and with single component bridges where the diode bridge is

wired internally.

Fig.(3.6): Bridge Rectifier

3.4.2 OPERATION

15

During positive half cycle of secondary, the diodes D2 and D3 are in forward

biased while D1 and D4 are in reverse biased as shown in the fig(3.7). The current

flow direction is shown in the fig.(3.7) with dotted arrows.

Fig.(3.7):Bridge Rectifier – Positive Half Cycle

During negative half cycle of secondary voltage, the diodes D1 and D4 are in

forward biased while D2 and D3 are in reverse biased as shown in the fig(3.8). The

current flow direction is shown in the fig.(3.8) with dotted arrows.

Fig.(3.8):Bridge Rectifier – Negative Half Cycle

3.5 FILTER

A Filter is a device which removes the ac component of rectifier output but allows the dc component to reach the load.

3.5.1 Capacitor Filter

16

The ripple content in the rectified output of half wave rectifier is 121% or that

of full-wave or bridge rectifier is 48%. Such high percentage of ripples is not

acceptable for most of the applications. Ripples can be removed by one of the

following methods of filtering.

A capacitor, in parallel to the load, provides an easier by-pass for the ripple

voltage through it due to low impedance at ripple frequency and leaves the dc to

appear at the load.

Filtering is performed by a large value electrolytic capacitor connected across

the DC supply to act as a reservoir, supplying current to the output when the varying

DC voltage from the rectifier is falling.

The capacitor charges quickly near the peak of the varying DC and then

discharges as it supplies current to the output. Filtering significantly increases the

average DC voltage to almost the peak value (1.4 × RMS value).

To calculate the value of capacitor(C),

C = ¼ * √3 * f * r * Rl

Where,

f = supply frequency,

r = ripple factor,

Rl = load resistance

3.6 REGULATOR

Voltage regulator ICs are available with fixed (typically 5, 12 and 15V) or

variable output voltages. The maximum current they can pass also rates them.

Negative voltage regulators are available, mainly for use in dual supplies.

17

Many of the fixed voltage regulators ICs have 3 leads and look like power

transistors, such as the 7805 +5V 1A regulator shown in the fig (3.5). The LM7805 is

simple to use.

The positive lead of an unregulated DC power supply (anything from 9V DC

to 24V DC) is connected to the input pin, and connect the negative lead to the

common pin and when the power is on, 5V appear at the output pin.

Fig.(3.9): A Three Terminal Voltage Regulator

3.6.1 LM78XX Description

The Bay Linear LM78XX is an integrated linear positive regulator with three

terminals. The LM78XX offer several fixed output voltages making them useful in

wide range of applications.

3.6.2 Features

• Output current of 1.5A

• Output voltage tolerance of 5%

• Internal thermal overload protection

• Internal short-circuit limited

• No external component

• Output voltage 5V, 6V, 8V, 9V, 10V, 12V, 15V, 18V, 24V

3.7 OSCILLATOR CHARACTERISTICS

18

The heart of the 8051 is the circuitry that generates the clock pulses by which

all internal operations are synchronized. Pins XTAL1 and XTAL2 are provided for

connecting a resonant network to form an oscillator typically a quartz crystal and

capacitors are employed. The crystal frequency is the basic internal clock frequency

of the microcontroller.

Fig.(3.10):Oscillator Connections

Fig.(3.11): External Clock Drive Configuration

3.8 LIGHT EMITTING DIODE

3.8.1 LED Description

It is a semiconductor diode having radioactive recombination. It requires a

definite amount of energy to generate an electron-hole pair.

19

The same energy is released when an electron recombines with a hole. This

released energy may result in the emission of photon and such a recombination. Here

the amount of energy released when the electro reverts from the conduction band to

the valence band appears in the form of radiation. Alternatively the released energy

may result in a series of phonons causing lattice vibration.

Finally the released energy may be transferred to another electron. The

recombination radiation may lie in the infra-red and visible light spectrum. In forward

it is peaked around the band gap energy and the phenomenon is called injection

luminescence.

In a junction biased, in the avalanche breakdown region, there results a

spectrum of photons carrying much higher energies, almost white light gets emitted

from micro-plasma breakdown region in silicon junction. Diodes having radioactive

recombination are termed as Light Emitting Diode, abbreviated as LED.

Fig.(3.12): Light Emitting Diode

Fig.(3.13): Circuit Symbol of LED

Testing an LED

Never 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.

3.8.2 CALCULATING AN LED RESISTOR VALUE

20

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

3.8.3 MERITS

The following are the merits of LED’s over conventional incandescent and other

types of lamps

1. Low working voltages and currents

2. Less power consumption

3. Very fast action

4. Emission of monochromatic light

5. small size and weight

6. No effect of mechanical vibrations

7. Extremely long life

Typical LED uses a forward voltage of about 2V and current of 5 - 10mA.

GaAs LED produces infra-red light while red, green and orange lights are produced

by gallium arsenide phosphide (GaAsP) and gallium phosphide (GaP).

21

3.9 INFRA - RED LED

3.9.1 IR LED DESCRIPTION

The QED233 / QED234 is a 940nm GaAs / AlGaAs LED encapsulated in a

clear untinted, plastic T-1 3/4 package.

Fig.(3.14): IR LED and Schematic

3.9.2 FEATURES

• Wavelength (λ) = 940 nm

• Chip material = GaAs with AlGaAs window

• Package type: T-1 3/4 (5mm lens diameter)

• Matched photo sensor: QSD122/123/124

• High output power

• Package, material and color: Clear, untinted, plastic

• Ideal for remote control applications

3.10 PHOTO DIODE

22

A photodiode is a type of photo detector capable of converting light into either

current or voltage, depending upon the mode of operation.

Photodiodes are similar to regular semiconductor diodes except that they may

be either exposed (to detect vacuum UV or X-rays) or packaged with a window or

optical fiber connection to allow light to reach the sensitive part of the device. Many

diodes designed for use specifically as a photodiode will also use a PIN junction

rather than the typical PN junction.

3.10.1 PRINCIPLE OF OPERATION

A photodiode is a PN junction or PIN structure. When a photon of sufficient

energy strikes the diode, it excites an electron thereby creating a mobile electron and a

positively charged electron hole. If the absorption occurs in the junction’s depletion

region, or one diffusion length away from it, these carriers are swept from the junction

by the built-in field of the depletion region. Thus holes move towards the anode and

electrons towards the cathode and a photocurrent is produced.

3.10.2 MATERIALS

The material used to make a photodiode is critical to define its properties,

because only photons with sufficient energy to excite electrons across the materials

band gap will produce significant photocurrents.

Table (2): Materials commonly used to produce photodiodes include

23

3.10.3 Features

Critical performance parameters of a photodiode include:

1) Excellent linearity with respect to incident light

2) Low noise

3) Wide spectral response

4) Mechanically rugged

5) Compact and lightweight

6) Long life

When a photodiode is used in an optical communication system, these

parameters contribute to the sensitivity of the optical receiver, which is the minimum

input power required for the receiver to achieve a specified bit error ratio.

24

4.1 SCHEMATIC DIAGRAM

25

Fig.(4): Schematic

4.2 SCHEMATIC DESCRIPTION

26

Power supply

The schematic diagram gives the basic hardware connections used in the

project. Beginning from the power supply the secondary of the step-down transformer

wires are given to the two ends (2, 4) of bridge rectifier which is having four diodes in

the bridge format. The other two ends (1, 3) are connected to the input (pin1) and

output (pin3) of the 7805 regulator and pin 2 is connected to ground as shown in

schematic diagram.

The 1000 micro farad capacitor is connected in between the bridge rectifier

and regulator to eliminate the ac ripples presented in the rectified output. The 100

microfarad capacitor is used to eliminate the noise at regulator output. Now 5V is

available at the pin 3 of regulator and connected to pin 40 of microcontroller.

AT89S51 Microcontroller

The 8051 microcontroller consist 40 pins and every pin has its own

functionality as shown in the schematic diagram.

The port 0 is having the pull up resistor which is having eight 10K resistors in

parallel each connected to the each pin of it.

IR LED

The IR LED is arranged with a resistor, in such a way that Vcc is applied to

the positive terminal of the IR LED. These are connected to the port 1 of the

microcontroller.

IR Receiver

27

The IR receivers are arranged with the transistor logic as shown in the

schematic diagram. The two transistors are connected in such a manner that collector

terminal is connected to the base terminal of the other. The photo diode is connected

to the base of the transistor along with the combination of the resistor.

The IR Receivers are connected to the P3.2, P3.3, P3.4, P3.5 pins of the

microcontroller.

5.1 RESULT

28

Our project showed a tremendous result in monitoring and controlling the

traffic by giving green signal for more amount of time to the road which had heavy

traffic and quite less time to the junction having less traffic, thereby reducing the

traffic density.

5.2 CONCLUSION

The project “TRAFFIC DENSITY ANALYZER CUM SIGNALING

FOR METRO CITIES” has been successfully designed and tested. Integrating

features of all the hardware components used have developed it. Presence of every

module has been reasoned out and placed carefully thus contributing to the best

working of the unit. Secondly, using highly advanced ICs and with the help of

growing technology the project has been successfully implemented.

BIBILOGRAPHY

29

1. The 8051 Microcontroller and Embedded systems- Muhammad Ali Mazidi and Janice Gillispi Mazidi

2. The 8051 Microcontroller Architecture, Programming & Applications - Kenneth J.Ayala

3. Microprocessor Architecture, Programming & Applications - Ramesh S.Gaonkar

4. Electronic Components - D.V.Prasad

5. www.atmel.databook.com

6. www.keil.com

7. www.national.com

8. www.atmel.com

9. www.wikipedia.com

10. www.microsoftsearch.com

SOURCE CODE

30

http://WWW.MICROSOFTSEARCH.COM/

http://www.wikipedia.com/

http://WWW.ATMEL.COM/

http://WWW.NATIONAL.COM/

http://www.keil.com/

http://WWW.ATMEL.DATABOOK.COM/

#include<reg51.h> //adding header files

sbit sensor1 = P3^2; //declaring the inputs and outputs

sbit sensor2 = P3^3;



sbit r_1 = P1^0;

sbit g_1 = P1^1;

sbit r_2 = P1^2;

sbit g_2 = P1^3;

sbit r_3 = P1^4;

sbit g_3 = P1^5;

sbit r_4 = P1^6;

sbit g_4 = P1^7;

void delay(unsigned int value) //definitions of sub-programs

{

unsigned int i,j;

for(i=0;i<value;i++)

for(j=0;j<100;j++);

}

void way1( )

{

g_4 = 1;

r_4 = 0;

g_1 = 0;

r_1 = 1;

}

void way2( )

31

{

g_1 = 1;

r_1 = 0;

g_2 = 0;

r_2 = 1;

}

void way3( )

{

g_2 = 1;

r_2 = 0;

g_3 = 0;

r_3 = 1;

}

void way4( )

{

g_3 = 1;

r_3 = 0;

g_4 = 0;

r_4 = 1;

}

void main( ) //starting the main program

{

r_1 = 0;

r_2 = 0;

r_3 = 0;

r_4 = 0;

while(1) //infinite loop

{

way1( );

if(sensor1 = = 1)

{

delay(7000);

}

else

32

delay(3000);

way2( );

if(sensor2 = = 1)

{

delay(7000);

}

else

delay(3000);

way3( );

if(sensor3 = = 1)

{

delay(7000);

}

else

delay(3000);

way4( );

if(sensor4 == 1)

{

delay(7000);

}

else

delay(3000);

}

}

33