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ROBUST TRAFFIC LIGHT CONTROLLER

UNDER THE GUIDANCE OF

ER.A.K.SINGH

BY:DEBASIS MISHRA

HISTORICAL PERSPECTIVE

• On 10 December 1868, the first traffic lights were installed outside the British Houses of Parliament in London, by the railway engineer J. P. Knight. They resembled railway signals of the time, with semaphore arms and red and green gas lamps for night use.

• The modern electric traffic light is an American invention. As early as 1912 in Salt Lake City, Utah, policeman Lester Wire invented the first red-green electric traffic lights.

TRAFFIC LIGHTS

• Traffic lights are also known as stop lights, traffic lamps, stop-and-go lights, robots or semaphore.

• These are signaling devices positioned at road intersections, pedestrian crossings and other locations to control competing flows 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).

OBSTACLES

• Redundancy is not present• Immune to failure due flow of large current• Voltage regulation is not proper• No augmented circuit is present when main

controller fails• Improper performance at different

temperature points

OBJECTIVEs

To make a robust traffic light controller

RedundancyVoltage regulationCurrent protectionImmune to Temperature

fluctuations

Controller

Traffic

Robust

MICROCONROLLER

THE BASIC 4 LANE TRAFFIC SIGNAL

STATE DIAGRAM

STATES OF LIGHTS OF LANES

AFTER4 SEC

AFTER50 SEC

CYCLIC ROTATION

Basic modules

• Four modules1. Power supply modules and Battery

backup module2. Microcontroller module3. Temperature regulated protection

module4. Overvoltage and overcurrent

protection module

Module-1

BASIC POWER SUPPLY CIRCUIT

LM7806=6V

Module-1 BASIC ZENER REGULATOR CIRCUIT

• Voltage regulation or stabilisation circuit

• Achieved through a ZENER DIODE

• ZENER break down occurs on applying reverse bias voltage

Module-1

6V BATTERY BACKUP SUPPLY

LM7806

• 131 Instructions• 32 8-bit GP registers• Throughput up to 16 MIPS• 16K programmable flash

(instructions)• 512Bytes EEPROM• 1K internal SRAM• Timers, serial and parallel

I/O, ADC

Module-2

ATMEGA 16 SPECIFICATIONS

Module-2

PIN DIAGRAM

Module-2

PROGRAMMING PORTS

• DDRA=0X00; (PORTA AS INPUT)• DDRA=0XFF; (PORTA AS OUTPUT)• PORTA=0XFF; (PORTA AS HIGH)• DELAY_MS(50); (USER DEFINED FUNCTION)• PORTA=0X00; (PORTA AS LOW) • DELAY_MS(50);

• Unsigned char read_portA;• read_portA=PINA;

Module-2

ADVANTAGE OF ATMEGA

• Less hardware complexity• Less power consumption• Faster operation• Cheap Programmer

HEADER FILE THAT WE USED = AVR/IO.H

4 PORTS ARE = A,B,C,D

3 BASIC COMMANDS TO PROGRAM THE PORTS ARE

DDR<PORT NAME>=<hex decimal or binary number>Used to declare ports as input or output port if 1=>output port, 0=>input portDDRA=0b01011100

PORT<PORT NAME>=<hex decimal or binary number>Used to assign output values through portPORTA=0b01011100

PIN<PORT NAME>=<hex decimal or binary number>Used to assign input values through portEg: PINA=0b01011100

Module-2BASIC COMMANDS FOR PROGRAMING THE PORTS OF AVR MICROCONTROLLER

Module-2SIMULATED CIRCUIT DIAGRAM FOR 4 LANE TRAFFIC LIGHT CONTROLLER

Module-2

‘C’ CODE FOR 4 LANE#include <AVR/IO.h>void Delay1s(int i){int j;volatile unsigned int cnt;for (j=0; j<i; j++)for (cnt = 0; cnt < 55555; cnt++); }void main(){ DDRA=0XFF; DDRB=0XFF; DDRC=0XFF; DDRD=0XFF; PORTA=0x01; PORTB=0x01; PORTC=0x01; PORTD=0x01;

Program for 1sec delay

Assigning all ports as output ports

Initializing values to ports

while(1) {PORTA=0x02;Delay1s(4);PORTA=0x04;Delay1s(20);PORTA=0x02;Delay1s(4);PORTA=0x01;

PORTB=0x02;Delay1s(4);PORTB=0x04;Delay1s(20);PORTB=0x02;Delay1s(2);PORTB=0x01;

Module-2

PORTC=0x02;Delay1s(4);PORTC=0x04;Delay1s(20);PORTC=0x02;Delay1s(4);PORTC=0x01;

PORTD=0x02;Delay1s(4);PORTD=0x04;Delay1s(20);PORTD=0x02;Delay1s(4);PORTD=0x01;}}

Loop continues infinite times

Module-2

PROBLEM STATEMENT OF 8 LANE TRAFFIC LIGHT CONTROLLER

• QUESTION• A vehicle coming from 1 can go in any

direction except 2 and 8 which are adjacent to the active lane.

• This is same for other lanes too.

SOLUTIONWe will take 2 lanes are active at a time i.e. let take 1 and 5.

Module-2

SIMULATION FOR 8 LANE Module-2

C CODE FOR 8 LANE TRAFFIC SIGNAL CONTROLLER

#include <AVR/IO.h>void Delay1s(int i){int j;volatile unsigned int cnt;for (j=0; j<i; j++);for (cnt = 0; cnt < 55555; cnt++); }void main(){ DDRA=0xFF; DDRB=0xFF; DDRC=0xFF; DDRD=0xFF; PORTA=0x01; PORTB=0x01; PORTC=0x01; PORTD=0x01; PORTA=0x02; Delay1s(4);

Module-2

while(1)• {PORTA=0x04;• Delay1s(20);• PORTA=0x02;• Delay1s(4);• PORTA=0x08;• Delay1s(20);• PORTA=0x02;• PORTB=0x02;• Delay1s(4);• PORTA=0x01;• PORTB=0x04;• Delay1s(20);• PORTB=0x02;• Delay1s(4);• PORTB=0x08;• Delay1s(20);• PORTB=0x02;• PORTC=0x02;• Delay1s(4);• PORTB=0x01;

Module-2

PORTC=0x04;Delay1s(20);PORTC=0x02;Delay1s(4);PORTC=0x08;Delay1s(20);PORTC=0x02;PORTD=0x02;Delay1s(4);PORTC=0x01;PORTD=0x04;Delay1s(20);PORTD=0x02;Delay1s(4);PORTD=0x08;Delay1s(20);PORTD=0x02;PORTA=0x02;Delay1s(4);PORTD=0x01;}}

Module-2

CIRCUIT DIAGRAM FOR MICROCONTROLLER BACK UP / MASTER SLAVE OPERATION OF MICROCONTROLLER

Module-2

THERMISTORS :Thermistor is a temperature-

sensing elementNegative temperature

coefficientsChemically stable and not

affected by aging

TEMPERATURE REGULATION PROTECTION MODULE

Module- 3

DC FANS : Automatic cooling fans to liberate heat out of the

circuits Operation controlled by thermistors Fan Motor 12V 700mA max. Use to cool down heat sinks

Module- 3

CIRCUIT DIAGRAM :

Module- 3

POLARITY PROTECTION MODULE

CIRCUIT DIAGRAM :

Module- 4

OVER VOLTAGE PROTECTION MODULE

CIRCUIT DIAGRAM :

Module- 4

Current Limiting Circuits(1A-2A)

• Normal operation• Output shorted, and no

limiting• Output shorted, with limiting

at 2A• Rsense=0.7/(Ilim)

CIRCUIT DIAGRAM :

Module- 4

CONCLUSION

• Major causes of failure are being countered• Microcontroller backup provides redundancy• High current and voltage values are made

limiting• Use of thermistors eliminate the dependency

of semiconductors on temperature• Sophisticated automatic traffic management is

the future aspect of this project

<<<***>>> [***Thank u***]<<<***>>>

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