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ROBUST TRAFFIC LIGHT CONTROLLER
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
Light
Traffic
Robust
MICROCONROLLER
THE BASIC 4 LANE TRAFFIC SIGNAL
STATE DIAGRAM
STATES OF LIGHTS OF LANES
AFTER4 SEC
AFTER4 SEC
AFTER50 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
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;
east
south
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;}}
north
west
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
TEMPERATURE REGULATION PROTECTION MODULE
Module- 3
CIRCUIT DIAGRAM :
TEMPERATURE REGULATION PROTECTION MODULE
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
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