VEHICLE DENSITY CONTROLLED AUTOMATIC TRAFFIC LIGHT from KMP Engineering college

VEHICLE DENSITY CONTROLLED AUTOMATIC TRAFFIC LIGHT
B.TECH 2014 1 Dept. Of EEE, KMPCE
CHAPTER 1
INTRODUCTION
The aim of this project is to solve traffic congestion which is a severe
problem in many modern cities all over the world. To solve the problem, we
have designed a framework for a dynamic and automatic traffic light
control system and developed a simulation model with codes in to help
build the system on hardware. Generally, each traffic light on an intersection is
assigned a constant green signal time. It is possible to propose dynamic time -
based coordination schemes where the green signal time of the traffic lights is
assigned based on the present conditions of traffic. The intelligent work which
is done by traffic inspector will be perfectly done by the micro controller
in the circuit with the help of sensors and the program which is coded to the
microcontroller.
Traffic lights have been installed in most cities around the world to control
the flow of traffic. They assign the right of way to road users by the use of lights
in standard colors (Red - Amber -Green), using a universal color code (and a
precise sequence, for those who are color blind). They are used at busy
intersections to more evenly apportion delay to the various users. The most
common traffic lights consist of a set of three lights: red, yellow (officially
amber), and green. When illuminated, the red light indicates for vehicles facing
the light to stop; the amber indicates caution, either because lights are about to
turn green or because lights are about to turn red; and the green light to proceed,
if it is safe to do so. There are many variations in the use and legislation of traffic
lights, depending on the customs of a country and the special needs of a particular
intersection. There may, for example, be special lights for pedestrians, bicycles,
buses, trams, etc.; light sequences may differ; and there may be special rules, or
sets of lights, for traffic turning in a particular direction. Complex intersections
may use any combination of these. Traffic light technology is constantly evolving
with the aims of improving reliability, visibility, and efficiency of traffic flow.

Conventional traffic light system is based on fixed time concept allotted to
each side of the junction which cannot be varied as per varying traffic density.
Junction timings allotted are fixed. Sometimes higher traffic density at one side of
the junction demands longer green time as compared to standard allotted time.
The proposed system using a microcontroller of 8051 series duly interfaced with
sensors, changes the junction timing automatically to accommodate movement of
vehicles smoothly avoiding unnecessary waiting time at the junction. The sensors
used in this project are IR and photodiodes are in line of sight configuration across
the loads to detect the density at the traffic signal. The density of the vehicles is
measured in three zones i.e., low, medium, high based on which timings are
allotted accordingly.
Further the project can be enhanced by synchronizing all the traffic
junctions in the city by establishing a network among them. The network can be
wired or wireless. This synchronization will greatly help in reducing traffic
congestion.
APPLICATIONS
There is no need of traffic inspector at the junctions for supervising the
traffic to run smoothly.
The intelligent work which is done by traffic inspector will be perfectly
done by the microcontroller in the circuit with the help of sensors and the
program which is coded to the microcontroller.
ADVANTAGES
Density based traffic light control have many advantages compared to time
based traffic control.
We can save considerable amount of time.
We can avoid unnecessary occurrence of traffic jams which causes public
inconvenience.

To monitor the density of the traffic, we will be keeping the few IR
Sensors in the besides the road and depends upon the signals from the sensors the
timing of the traffic signals will be changed. The sensors output is given to a
comparator to digitize the output.
In this project all the IR receivers placed near the roads are connected to
one controller & the traffic signals are connected to another controller. Based on
the IR receivers signal information will be send to the signal connected controller
using Zigbee. Both the controller will communicate with each other using pair of
Zigbee.
Initially traffic signal connected Zigbee will send signal to the IR receiver
connected controller trough Zigbee to monitor the particular road. IR receivers
connected controller will monitor the road indicated by the controller. If the 1st IR
is blocked means that particular road signal will be switched to green light for
30sec, if the vehicles blocked till 2nd IR means that particular signal will be
switched to 35sec & the signal time will be displayed on the LCD. If IR’s are not
blocked means by default 10 seconds traffic signal delay will be there. [2]
.
The heart of the embedded system is the microcontroller. 8051 architecture
based P89V51RD2 microcontroller from NxP is used to implement this project.
Microcontroller acts as the heart of the project, which controls the whole system.
It contains 1k RAM, 64k Flash, 3 Timers, 2 external interrupts, 1 UART, 32
GPIO’s, ISP programming support etc. KEIL IDE is used to program the
microcontroller and the coding will be done using Embedded C.

CHAPTER 2
THE POWER STAGE
2.1 Power Supply
Power supply is a reference to a source of electrical power. A device or
system that supplies electrical or other types of energy to an output load or group
of loads is called a power supply unit or PSU. The term is most commonly applied
to electrical energy supplies, less often to mechanical ones, and rarely to others.
Here in our application we need a 5v DC power supply for all electronics involved
in the project. This requires step down transformer, rectifier, voltage regulator,
and filter circuit for generation of 5v DC power.
2.2 Components Used
2.2.1 Transformer
Transformer is a device that transfers electrical energy from one circuit to
another through inductively coupled conductors — the transformer's coils or
"windings". Except for air-core transformers, the conductors are commonly
wound around a single iron-rich core, or around separate but magneticallycoupled
cores. A varying current in the first or "primary" winding creates a varying
magnetic field in the core (or cores) of the transformer. This varying magnetic
field induces a varying electromotive force (EMF) or "voltage" in the "secondary"
winding. This effect is called mutual induction.
Figure 2.1: Transformer

If a load is connected to the secondary circuit, electric charge will flow in
the secondary winding of the transformer and transfer energy from the primary
circuit to the load connected in the secondary circuit.
The secondary induced voltage VS, of an ideal transformer, is scaled from the
primary VP by a factor equal to the ratio of the number of turns of wire in their
respective windings:
𝑉𝑆
𝑉𝑃
=
𝑁𝑆
𝑁 𝑃
By appropriate selection of the numbers of turns, a transformer thus allows an
alternating voltage to be stepped up — by making NS more than NP— or stepped
down.
Refer to the transformer circuit in figure as you read the following
explanation: The primary winding is connected to a 60-hertz ac voltage source.
The magnetic field (flux) builds up (expands) and collapses (contracts) about the
primary winding. The expanding and contracting magnetic field around the
primary winding cuts the secondary winding and induces an alternating voltage
into the winding. This voltage causes alternating current to flow through the load.
The voltage may be stepped up or down depending on the design of the primary
and secondary windings.
2.2.2 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.
According to the conventional model of current flow originally established
by Benjamin Franklin and still followed by most engineers today, current is
assumed to flow through electrical conductors from the positive to the negative
pole. In actuality, free electrons in a conductor nearly always flow from the
negative to the positive pole. In the vast majority of applications, however, the
actual direction of current flow is irrelevant. Therefore, in the discussion below
the conventional model is retained.

In the diagram Fig 2.2 , when the input connected to the left corner of the
diamond is positive, and the input connected to the right corner is negative,
current flows from the upper supply terminal to the right along the red (positive)
path to the output,
When the input connected to the left corner is negative, and the input
connected to the right corner is positive, current flows from the lower supply
terminal to the right along the red path to the output, and returns to the upper
supply terminal via the blue path.
Figure 2.2: Bridge Rectifier
In each case, the upper right output remains positive and lower right output
negative. Since this is true whether the input is AC or DC, this circuit not only
produces a DC output from an AC input, it can also provide what is sometimes
called "reverse polarity protection". That is, it permits normal functioning of DC-
powered equipment when batteries have been installed backwards, or when the
leads (wires) from a DC power source have been reversed, and protects the
equipment from potential damage caused by reverse polarity.
Prior to availability of integrated electronics, such a bridge rectifier was
always constructed from discrete components. Since about 1950, a single four-
terminal component containing the four diodes connected in the bridge
configuration became a standard commercial component and is now available
with various voltage and current ratings.
. 2.2.3RegulatorIC (78XX)
It is a three pin IC used as a voltage regulator. It converts unregulated DC
current into regulated DC current.

Figure 2.3 Regulator IC
Normally we get fixed output by connecting the voltage regulator at the
output of the filtered DC (see in above diagram). It can also be used in circuits to
get a low DC voltage from a high DC voltage (for example we use 7805 to get 5V
from 12V). There are two types of voltage regulators 1. Fixed voltage regulators
(78xx, 79xx) 2. Variable voltage regulators (LM317) in fixed voltage regulators
there is another classification 1. +ve voltage regulators 2. -ve voltage regulators
positive voltage regulators this include 78xx voltage regulators. The most
commonly used ones are 7805 and 7812. 7805 gives fixed 5V DC voltage if input
voltage is in (7.5V, 20V).
2.2.4The Capacitor Filter
The simple capacitor filter is the most basic type of power supply filter.
The application of the simple capacitor filter is very limited. It is sometimes used
on extremely high-voltage, low-current power supplies for cathode-ray and similar
electron tubes, which require very little load current from the supply. The
capacitor filter is also used where the power-supply ripple frequency is not
critical; this frequency can be relatively high. The capacitor (C1) shown in figure
2.4 is a simple filter connected across the output of the rectifier in parallel with the
load.
Figure 2.4: Full-wave rectifier with a capacitor filter.

When this filter is used, the RC charge time of the filter capacitor (C1)
must be short and the RC discharge time must be long to eliminate ripple action.
In other words, the capacitor must charge up fast, preferably with no discharge at
all. Better filtering also results when the input frequency is high; therefore, the
full-wave rectifier output is easier to filter than that of the half-wave rectifier
because of its higher frequency.
For you to have a better understanding of the effect that filtering has on
Eavg, a comparison of a rectifier circuit with a filter and one without a filter is
illustrated in views. The output waveforms represent the unfiltered and filtered
outputs of the half-wave rectifier circuit. Current pulses flow through the load
resistance (RL) each time a diode conducts. The dashed line indicates the average
value of output voltage. For the half-wave rectifier, Eavg is less than half (or
approximately 0.318) of the peak output voltage. This value is still much less than
that of the applied voltage. With no capacitor connected across the output of the
rectifier circuit, the waveform in view A has a large pulsating component (ripple)
compared with the average or dc component. When a capacitor is connected
across the output (view B), the average value of output voltage (Eavg) is increased
due to the filtering action of capacitor C1.
2.2.5DIODE
The diode is a p-n junction device. Diode is the component used to control
the flow of the current in any one direction. The diode widely works in forward
bias. When the current flows from the P to N direction. Then it is in forward
bias. The Zener diode is used in reverse bias function i.e. N to P direction.
Visually the identification of the diode`s terminal can be done by identifying he
silver/black line. The silver/black line is the negative terminal (cathode) and the
other terminal is the positive terminal (cathode).
2.2.6 RESISTORS
The flow of charge through any material encounters an opposing force
similar in many respects to mechanical friction .this opposing force is called
resistance of the material .in some electric circuit resistance is deliberately
introduced in form of resistor. Resistor used fall in three categories , only two of

which are color coded which are metal film and carbon film resistor .the third
category is the wire wound type ,where value are generally printed on the vitreous
paint finish of the component. Resistors are in ohms and are represented in Greek
letter omega, looks as an upturned horseshoe. Most electronic circuit require
resistors to make them work properly and it is obliviously important to find out
something about the different types of resistors available. Resistance is measured
in ohms, the symbol for ohm is an omega ohm. 1 ohm is quite small for
electronics so resistances are often given in kΩ and MΩ. Resistors used in
electronics can have resistances as low as 0.1 Ω or as high as 10 MΩ.Resistor
restrict the flow of electric current, for example a resistor is placed in series with a
light-emitting diode (LED) to limit the current passing through the LED.
2.2.7 CAPACITORS
In a way, a capacitor is a little like a battery. Although they work in
completely different ways, capacitors and batteries both store electrical energy. If
you have read How Batteries Work, then you know that a battery has two
terminals. Inside the battery, chemical reactions produce electrons on one terminal
and absorb electrons at the other terminal.
Like a battery, a capacitor has two terminals. Inside the capacitor, the
terminals connect to two metal plates separated by a dielectric. The dielectric can
be air, paper, plastic or anything else that does not conduct electricity and keeps
the plates from touching each other. You can easily make a capacitor from two
pieces of aluminum foil and a piece of paper. It won't be a particularly good
capacitor in terms of its storage capacity, but it will work. In an electronic
circuit, a capacitor is shown like this:
Figure 2.2.5: Capacitor

When you connect a capacitor to a battery, here’s what happens:
•The plate on the capacitor that attaches to the negative terminal of the battery
accepts electrons that the battery is producing.
•The plate on the capacitor that attaches to the positive terminal of the battery
loses electrons to the battery.
2.2.8 LED
LED falls within the family of P-N junction devices. The light emitting
diode (LED) is a diode that will give off visible light when it is energized. In any
forward biased P-N junction there is, with in the structure and primarily close to
the junction, a recombination of hole and electrons. This recombination requires
that the energy possessed by the unbound free electron be transferred to another
state. The process of giving off light by applying an electrical source is called
electroluminescence.
LED is a component used for indication. All the functions being carried
out are displayed by led .The LED is diode which glows when the current is being
flown through it in forward bias condition. The LEDs are available in the round
shell and also in the flat shells. The positive leg is longer than negative leg.
Fig 2.2.6 Led

CHAPTER 3
THE CONTROL STAGE
3.1 The 8051Microcontroller
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
pinout. 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.
The AT89S51 provides the following standard features: 4K bytes of Flash,
128 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit
timer/counters, a fivevector two-level interrupt architecture, a full duplex serial
port, on-chip oscillator, and clock circuitry. In addition, the AT89S51 is designed
with static logic for operation down to zero frequency and supports two software
selectable power saving modes. The Idle Mode stops the CPU while allowing the
RAM, timer/counters, serial port, and interrupt system to continue functioning.
The Power-down mode saves the RAM contents but freezes the oscillator,
disabling all other chip functions until the next external interrupt or hardware
reset. [1]
Features
1. Compatible with MCS-51® Products
2. 4K Bytes of In-System Programmable (ISP) Flash Memory
a. Endurance: 1000 Write/Erase Cycles
3. 4.0V to 5.5V Operating Range
4. Fully Static Operation: 0 Hz to 33 MHz

5. Three-level Program Memory Lock
6. 128 x 8-bit Internal RAM
7. 32 Programmable I/O Lines
8. Two 16-bit Timer/Counters
9. Six Interrupt Sources
10. Full Duplex UART Serial Channel
11. Low-power Idle and Power-down Modes
12. Interrupt Recovery from Power-down Mode
13. Watchdog Timer
14. Dual Data Pointer
15. Power-off Flag
16. Fast Programming Time
17. Flexible ISP Programming (Byte and Page Mode)
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 Indus-try-standard 80C51 instruction set
and pinout. 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.
The AT89S51 provides the following standard features: 4K bytes of Flash,
128 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, two 16-bit
timer/counters, a five-vector two-level interrupt architecture, a full duplex serial
port, on-chip oscillator, and clock circuitry. In addition, the AT89S51 is designed
with static logic for operation down to zero frequency and supports two software
selectable power saving modes. The Idle Mode stops the CPU while allowing the
RAM, timer/counters, serial port, and interrupt system to continue functioning.

The Power-down mode saves the RAM con-tents but freezes the oscillator,
disabling all other chip functions until the next external interrupt or hardware
reset.
Figure 3.1: Pin diagram
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 1s 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 accesses 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 1s 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.
Table 3.1 Port alternate functions
Port Pin Alternate Functions
P1.5 MOSI (used for In-System Programming)
P1.6 MISO (used for In-System Programming)
P1.7 SCK (used for In-System Programming)
because of the internal pull-ups.
Port 2 emits the high-order address byte during fetches from external program
memory and during accesses to external data memory that use 16-bit addresses
(MOVX @ DPTR). In this application, Port 2 uses strong internal pull-ups when
emitting 1s. During accesses to external data memory that use 8-bit addresses
(MOVX @ RI), Port 2 emits the contents of the P2 Special Function Register.
Port 2 also receives the high-order address bits and some control signals during
Flash programming and verification.

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 3.2 Port 3-alternate functions
RST:Reset input. A high on this pin for two machine cycles while the oscillator is
running resets the device. This pin drives High for 98 oscillator periods after the
Watchdog times out. The DISRTO bit in SFR AUXR (address 8EH) can be used
to disable this feature. In the default state of bit DISRTO, the RESET HIGH out
feature is enabled.
Port Pin Alternate Functions
P3.0 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)

ALE/PROG Address Latch Enable (ALE) is an output pulse for latching the low
byte of the address during accesses to external memory. This pin is also the
program pulse input (PROG) during Flash programming.
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 activatedtwice 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 up to FFFFH. Note, 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.
XTAL1Input to the inverting oscillator amplifier and input to the internal clock
Operating circuit.
XTAL2Output from the inverting oscillator amplifier
Special A map of the on-chip memory area called the Special Function Register
(SFR) space is shown
User software should not write 1s to these unlisted locations, since they may be
used in future products to invoke new features. In that case, the reset or inactive
values of the new bits will always be 0. [1]

CHAPTER 4
SENSORS
An infrared sensor is an electronic instrument that is used to sense certain
characteristics of its surroundings by either emitting and/or detecting infrared
radiation. It is also capable of measuring heat of an object and detecting motion.
Infrared waves are not visible to the human eye.
In the electromagnetic spectrum, infrared radiation is the region having
wavelengths longer than visible light wavelengths, but shorter than microwaves.
The infrared region is approximately demarcated from 0.75 to 1000µm. The
wavelength region from 0.75 to 3µm is termed as near infrared, the region from 3
to 6µm is termed mid-infrared, and the region higher than 6µm is termed as far
infrared.
Fig 4.1 Object Sensor
Fig4.2 IR Diodes

An infrared sensor is an electronic device that emits and/or detects infrared
radiation in order to sense some aspect of its surroundings. Infrared sensors can
measure the heat of an object, as well as detect motion. Many of these types of
sensors only measure infrared radiation, rather than emitting it, and thus are
known as passive infrared (PIR) sensors.
All objects emit some form of thermal radiation, usually in the infrared
spectrum. This radiation is invisible to our eyes, but can be detected by an infrared
sensor that accepts and interprets it. In a typical infrared sensor like a motion
detector, radiation enters the front and
reaches the sensor itself at the center of
the device. This part may be composed
of more than one individual sensor, each
of them being made from pyro electric
materials, whether natural or artificial.
These are materials that generate an
electrical voltage when heated or cooled.
Requirements
 5V DC regulated power supply
 IR Receiver (1 pc)
 IR led (1 pc) Fig 4.3 circuit for sensor
 resistors (1K, 330R)
 Trim resistors-known as trimmer resistor (2pc.)
 Bread board and Vero board (or copper clad board if you want to make a unique
pcb)
 connection wires
 jumper and berg strip(optional)
 soldering equipment

CHAPTER 5
FLOW CHART AND CIRCUIT DIAGRAM
NO
No
START
INITIALIZE TIMER0 AS TIMER
Start by giving yellow on all side
North yellow is on and north red is
off
Go to subroutine delayy
North green on and others red on
Go to subroutine delay
Checkfor densityonnorth
Count=0
Decrement count
East yellow isonandEast redisoff
Checkfor densityon
East side and=count
A
C

A
Go to subroutine delay y
East green on and others red on
Count=0
Decrement count
Southyellow isonandSouthred isoff
South green on and others red on
Checkfor densityon
Southside and=count
Count=0
Decrement count
B

CH
B
Westyellow isonand Westredis off
West green on and others red on
Checkfor densityonWest
side and=count
Count=0
Decrement count
C

CIRCUIT DIAGRAM
Figure 5.1: Circuit Diagram

BLOCK DIAGRAM
Fig 5.2 block diagram
VEHICLE DENSITY CONROLLED AUTOMATIC TRAFFIC LIGHT
WORKING:
In this system IR sensors are used to measure the density of the vehicles
whichare fixed within a fixed distance. All the sensors are interfaced with the
microcontrollerwhich in turn controls the traffic signal system according to
density detected by thesensors.
To monitor the density of the traffic, we will be keeping the few IR
Sensors in the besides the road and depends upon the signals from the sensors the
timing of the traffic signals will be changed. The sensors output is given to a
comparator to digitize the output.
IR NORTH
AT 89S51
TRAFFIC
LIGHTS
LED
ARRAYIR SOUTH
IR EAST
IR WEST
Step-down
Transformer
Bridge
Rectifier
Filter
Circuit
Regulator Power supply
To all

In this project all the IR receivers placed near the roads are connected to
one controller & the traffic signals are connected to another controller. Based on
the IR receivers signal information will be send to controller.
Initially traffic signal connected will send signal to the IR receiver
connected controller to monitor the particular road. IR receivers connected
controller will monitor the road indicated by the controller. If the 1st IR is blocked
means that particular road signal will be switched to green light for 20sec, if the
vehicles blocked till 2nd IR means that particular signal will be switched to 30sec
and if the vehicles blocked till 3rd IR means that particular signal will be switched
to 40sec. If IR’s are not blocked means by default 10 seconds traffic signal delay
will be there. [2]
The control is executed in a closed loop. First it starts from the north side.
Just before going to north side micro controller will checkthe density at that side
and the counter value corresponding to the density is stored and green light is
turned on. Before going to the next stage the micro controller will check the
density at the next stage at the time of yellow signal in present state and so on.
In this system IR sensors are used to measure the density of the vehicles
whichare fixed within a fixed distance. It consists of an IR transmitter and receiver
placed in the same side. The IR transmitter always transmits IR rays, when a
vehicle cuts the rays, or when an object comes in front of the module the IR rays
reflected and receiver gets the signal and t informs themicrocontroller.
Fig 5.3 Sensor Circuits

CHAPTER 6
RESULTS AND CONCLUSION
We can conclude that using the method of density based control of traffic
lights we can save a considerable amount of time and also we can prevent
excessive traffic jams thus leading to smooth traffic flow. Presently in India we
are following time based control of traffic signals and we are experiencing a
heavy traffic jams all over which in turn consumes lot of time and fuel. We hope
these methods will be adopted as soon as possible so that the limitations we are
experiencing with present method can be overcome.
In the process of realizing this project, the construction was initially
carried out on a breadboard to allow for checking and to ascertain that it is
functioning effectively. All irregularities were checked then tested and found to
have a satisfactory output. The component were then removed and transferred to a
Vero board strip and soldered into place and all discontinuous point were cut out
to avoid short-circuiting.
This project can be enhanced in such a way as to control automatically the
signals depending on the traffic density on the roads using sensors like metal
detector modules or by the application of neural networks extended with
automatic turn off when no vehicles are running on any side of the road which
helps in power consumption saving.

REFERENCES
[1] AT89s51 data sheet, Atmel Corporation, 2011.
[2] Madhavi Arora, V. K. Banga, "Real Time Traffic Light Control System", 2nd
International Conference on Electrical, Electronics and Civil Engineering
(ICEECE'2012), pp. 172-176, Singapore, April 28-29, 2012.
[3] Sabyasanchikanojia, "Real –time Traffic light control and Congestion
voidancesystem", International Journal of Engineering Research and
Applications (IJERA), Vol. 2, Issue 2,Mar-Apr 2012,pp. 925-929.
[4] Muhammad Ali Mazidi and Janice Gillis pie Mazidi,”The 8051
Microcontroller
And EmbeddedSystemsUsing Assembly and C” Second Edition
[5]http://www.coregravity.com/html/detecting_obstacle_with_ir__in.html (as on
23.4.2014)

APPENDIX 1
AT89S51 BLOCK DIAGRAM

APPENDIX 2
MICROCONTROLLER PROGRAM
; DYNAMICALLY CHANGED VEHICLE DENSITY CONTROLLED
; AUTOMATIC TRAFFIC CONTROL
;*******************************************
; OUTPUT PINS
NG EQU P2.0
NR EQU P2.1
NY EQU P2.2
EG EQU P2.3
ER EQU P2.4
EY EQU P2.5
SG EQU P2.6
SR EQU P2.7
SY EQU P3.0
WG EQU P3.1
WRR EQU P3.2
WY EQU P3.3
; INPUT PINS
N1 EQU P3.4
N2 EQU P3.5
N3 EQU P3.6
E1 EQU P3.7

E2 EQU P1.0
E3 EQU P1.1
S1 EQU P1.2
S2 EQU P1.3
S3 EQU P1.4
W1 EQU P1.5
W2 EQU P1.6
W3 EQU P1.7
ORG 00H
LJMP MAIN
ORG 50H
MAIN: MOV TMOD, #10H
MOV A,#00H
MOV P2,A
MOV A,#0FH
MOV P3,A
MOV A,#0FFH
MOV P1,A
SETB NY
SETB EY
SETB SY
SETB WY
ACALL DELAYY
SETB NR
SETB ER
SETB SR
SETB WRR
CLR NY
CLR EY
CLR SY
CLR WY

START: SETB WY
CLR WG
MOV R1,#00H
ACALL NORTH
ACALL DELAYY
CLR WY
SETB WRR
SETB NG
CLR NR
ACALL DELAY
CLR NG
SETB NY
MOV R1,#00H
ACALL EAST
ACALL DELAYY
CLR NY
SETB NR
SETB EG
CLR ER
ACALL DELAY
CLR EG
SETB EY
MOV R1,#00H
ACALL SOUTH
ACALL DELAYY
CLR EY
SETB ER
SETB SG
CLR SR
ACALL DELAY
CLR SG

SETB SY
MOV R1,#00H
ACALL WEST
ACALL DELAYY
CLR SY
SETB SR
SETB WG
CLR WRR
ACALL DELAY
LJMP START
NORTH: JNB N3,N_2
MOV R1,#4
RET
N_2: JNB N2,N_1
MOV R1,#3
RET
N_1: JNB N1,N_0
MOV R1,#2
RET
N_0: MOV R1,#1
RET
EAST: JNB E3,E_2
MOV R1,#4
RET
E_2: JNB E2,E_1
MOV R1,#3
RET
E_1: JNB E1,E_0
MOV R1,#2
RET
E_0: MOV R1,#1

RET
SOUTH: JNB S3,S_2
MOV R1,#4
RET
S_2: JNB S2,S_1
MOV R1,#3
RET
S_1: JNB S1,S_0
MOV R1,#2
RET
S_0: MOV R1,#1
RET
WEST: JNB W3,W_2
MOV R1,#4
RET
W_2: JNB W2,W_1
MOV R1,#3
RET
W_1: JNB W1,W_0
MOV R1,#2
RET
W_0: MOV R1,#1
RET
;SUBROUTINE FOR 10 sec DELAY
DELAY: MOV R0,#8FH
LOOP1: MOV TH1,#03H
MOV TL1,#0FBH
SETB TR1
RPT: JNB TF1,RPT

CLR TR1
CLR TF1
DJNZ R0,LOOP1
DJNZ R1, DELAY
RET
;SUBROUTINE FOR 5 sec DELAY
DELAYY: MOV R0,#47H
LOOP: MOV TH1,#03H
MOV TL1,#0FBH
SETB TR1
AGAIN: JNB TF1,AGAIN
CLR TR1
CLR TF1
DJNZ R0,LOOP
RET
END

VEHICLE DENSITY CONTROLLED AUTOMATIC TRAFFIC LIGHT from KMP Engineering college

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