This document describes a student project to create a traffic light controller using an AT89C51 microcontroller. It provides background on the history of traffic lights, descriptions of red, yellow, and green light meanings. The project components include an AT89C51 microcontroller, LED lights, resistors, capacitors, and a crystal oscillator. The microcontroller is programmed to automatically change the LED light signals after a time interval by setting the corresponding port pins high and low. The motivation is that it is a basic microcontroller application. There is opportunity to enhance it to control signals automatically based on sensor detection of traffic density.

1. A MINOR PROJECT ON
TRAFFIC LIGHT
CONTROLLER
Based on AT89C51 Microcontroller
Presented By:
Ramkrishna Mishra (5910428)

2. 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

3. 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.

4. 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.

5. 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.

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

7. 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.

8. 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.

9. COMPONEN
TS
AT89C51 Microcontroller
Capacitor (30pF x2,10µF)
Resistor (8.2KΩ)
Crystal oscillator (11.0592MHz)
LED
light (Red, Green, Blue)
PCB
Power supply

10. BLOCK DIAGRAM

11. CIRCUIT DIAGRAM

12. 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.

13. 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)

14. {
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();
}
}

15. 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.

16. 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.