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A MINOR PROJECT ON
TRAFFIC LIGHT
CONTROLLER

Based on AT89C51 Microcontroller

Presented By:
Ramkrishna Mishra (5910428)

HISTORY OF TRAFFIC
LIGHT were invented by J
The world's very first traffic lights
P Knight installed near London's House of Commons,
which was on the intersection of George and Bridge
Street, in 1868.
In

1914 The American Traffic Signal Company
installed red and green traffic lights on every corner
of the intersection of 105th Street and Euclid Avenue
in Cleveland, Ohio.

First

traffic lights were all controlled by either timing,
or manually switched

RED
Come

to complete stop at stop line or before crosswalk
or intersection.
After stopping, you may turn right on red
at most intersections if the way is clear.
Some school districts have local policies that prohibit
right turns on red by bus operators.
Some intersections display “NO TURN ON RED,”
which you must obey.

YELLOW
Stop
The

if you can do so safely.

light will soon be red.

GREEN
Go,
If

but only if intersection is clear.

turning left, wait for gap in oncoming traffic to
complete turn.

Few things about AT89C51
 It has four Ports:
Port 0
Port 1
Port 2
Port 3
These Four ports works as Input port as
well as output port.

ABSTRACT
The function of traffic lights is to provide
sophisticated control and coordination to
ensure that traffic moves as smoothly and
safely as possible.

FEATURES OF TRAFFIC LIGHT CONTROLLER
controller assumes

equal traffic density on

all the roads.
The

free left turn condition is provided
throughout the entire signal period.

The

control can also be exercised manual
when desired.

INTRODUCTION
•

This project uses a LED light as an indicator.

•

A microcontroller for auto change signal after a
specific time interval.

•

The LEDs are automatically on and off by
making the corresponding port pin of the micro
controller high.

COMPONEN
TS
AT89C51 Microcontroller
Capacitor (30pF x2,10µF)
Resistor (8.2KΩ)
Crystal oscillator (11.0592MHz)
LED

light (Red, Green, Blue)

PCB
Power supply

WORKIN
G
 The

pins of the various input output ports of the

microcontroller are connected directly to the
given LEDs.
 The

8051 is programmed in a manner that the

respective LEDs glow by setting the required bit
using assembly language and a certain amount
of delay is provided depending on the user.

PROGRAM
#include<reg51.h>
sbit RE = P0^0;
sbit YE = P0^1;
sbit GE = P0^2;
sbit RW = P0^3;
sbit YW = P0^4;
sbit GW = P0^5;
sbit RN = P0^6;
sbit YN = P0^7;

sbit GN = P2^0;
sbit RS = P2^1;
sbit YS = P2^2;
sbit GS = P2^3;
void Delay(void)

{
unsigned int j;//,i;
////for(i=0;i<200;i++)
for(j=0;j<700;j++);
}
void SuperDelay()
{
unsigned int i;
for (i=0;i<25;i++);
Delay();
}

void main()
{
while (1)
{
RE=0; GE=1; YE=0;
RW=1; GW=0; YW=0;
RN=1; GN=0; YN=0;
RS=1; GS=0; YS=0;
SuperDelay();

GE=0; YE=1;
Delay();
RE=1; GE=0; YE=0;
RW=0; GW=1; YW=0;
RN=1; GN=0; YN=0;
RS=1; GS=0; YS=0;
SuperDelay();
GW=0; YW=1;
Delay();
RE=1; GE=0; YE=0;
RW=1; GW=0; YW=0;
RN=0; GN=1; YN=0;
RS=1; GS=0; YS=0;
SuperDelay();
GN=0; YN=1;
Delay();
RE=1; GE=0; YE=0;
RW=1; GW=0; YW=0;
RN=1; GN=0; YN=0;
RS=0; GS=1; YS=0;
SuperDelay();
GS=0; YS=1;
Delay();
}
}

MOTIVATION
The

project finds high practical and
widespread use.

It

is a very primitive application of
the microcontroller.

Easy

and convenient to be built for
a beginner as the coding comprises
of basic instructions.

SCOP
E
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 IR
detector/receiver module extended with
automatic turn off when no vehicles are
running on any side of the road which helps
in power consumption saving.

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Traffic light controller

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