This document describes the design of a robust traffic light controller. It discusses the historical use of traffic lights and outlines objectives to make the controller redundant, regulate voltage, protect from overcurrent and temperature fluctuations. It then describes the basic modules used - a power supply with battery backup, a microcontroller module, a temperature regulation module, and overvoltage/current protection. Code examples are provided for programming the microcontroller ports to control 4-lane and 8-lane traffic light sequences. Diagrams show the circuit designs for the modules. The conclusion states that this controller aims to address major failure causes through redundancy, limiting high voltages/currents, and protecting from temperature changes.

1. ROBUST TRAFFIC LIGHT CONTROLLER

2. ROBUST TRAFFIC LIGHT
CONTROLLER
UNDER THE GUIDANCE OF
ER.A.K.SINGH
BY:
DEBASIS MISHRA

3. 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.

4. 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).

5. 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

6. OBJECTIVEs Robust
Traffic
To make a robust traffic
Light
light controller
Redundancy
Voltage regulation MICROCONROLLER
Controller
Current protection
Immune to Temperature
fluctuations

7. THE BASIC 4 LANE TRAFFIC SIGNAL

8. STATE DIAGRAM

9. STATES OF LIGHTS OF LANES
AFTER
50 SEC
CYCLIC AFTER
AFTER ROTATION 4 SEC
4 SEC
AFTER
50 SEC

10. Basic modules
• Four modules
1. Power supply modules and Battery
backup module
2. Microcontroller module
3. Temperature regulated protection
module
4. Overvoltage and overcurrent
protection module

11. Module-1
BASIC POWER SUPPLY CIRCUIT
=6V
LM7806

12. 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

13. Module-1
6V BATTERY BACKUP SUPPLY
LM7806

14. Module-2
ATMEGA 16 SPECIFICATIONS
• 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

15. Module-2
PIN DIAGRAM

16. Module-2

17. 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;

18. Module-2
ADVANTAGE OF ATMEGA
• Less hardware complexity
• Less power consumption
• Faster operation
• Cheap Programmer

19. Module-2
BASIC COMMANDS FOR PROGRAMING
THE PORTS OF AVR MICROCONTROLLER
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 port
DDRA=0b01011100
PORT<PORT NAME>=<hex decimal or binary number>
Used to assign output values through port
PORTA=0b01011100
PIN<PORT NAME>=<hex decimal or binary number>
Used to assign input values through port
Eg: PINA=0b01011100

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

21. Module-2
‘C’ CODE FOR 4 LANE
#include <AVR/IO.h>
void Delay1s(int i)
{
int j; Program
volatile unsigned int cnt; for
for (j=0; j<i; j++) 1sec delay
for (cnt = 0; cnt < 55555; cnt++);
}
void main()
{
DDRA=0XFF;
DDRB=0XFF; Assigning all
DDRC=0XFF; ports as
DDRD=0XFF; output ports
PORTA=0x01;
PORTB=0x01; Initializing values
PORTC=0x01; to ports
PORTD=0x01;

22. Module-2
while(1) east
{
PORTA=0x02;
Delay1s(4);
PORTA=0x04;
Delay1s(20);
PORTA=0x02;
Delay1s(4);
PORTA=0x01; south
PORTB=0x02;
Delay1s(4);
PORTB=0x04;
Delay1s(20);
PORTB=0x02;
Delay1s(2);
PORTB=0x01;

23. Module-2
north
PORTC=0x02;
Delay1s(4);
PORTC=0x04;
Delay1s(20);
PORTC=0x02;
Delay1s(4);
PORTC=0x01; west
PORTD=0x02;
Delay1s(4);
PORTD=0x04;
Delay1s(20);
PORTD=0x02;
Delay1s(4);
PORTD=0x01;
} Loop continues infinite times
}

24. 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.
SOLUTION
We will take 2 lanes are active at a
time i.e. let take 1 and 5.

25. Module-2
SIMULATION FOR 8 LANE

26. 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);

27. 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;

28. 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;}
}

29. Module-2
CIRCUIT DIAGRAM FOR MICROCONTROLLER BACK UP /
MASTER SLAVE OPERATION OF MICROCONTROLLER

30. Module- 3
TEMPERATURE REGULATION
PROTECTION MODULE
THERMISTORS :
Thermistor is a temperature-
sensing element
Negative temperature
coefficients
Chemically stable and not
affected by aging

31. Module- 3
TEMPERATURE REGULATION
PROTECTION MODULE
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

32. Module- 3
TEMPERATURE REGULATION
PROTECTION MODULE
CIRCUIT DIAGRAM :

33. Module- 4
POLARITY PROTECTION MODULE
CIRCUIT DIAGRAM :

34. Module- 4
OVER VOLTAGE PROTECTION MODULE
CIRCUIT DIAGRAM :

35. Module- 4
Current Limiting Circuits(1A-2A)
CIRCUIT DIAGRAM :
• Normal operation
• Output shorted, and no
limiting
• Output shorted, with limiting
at 2A
• Rsense=0.7/(Ilim)

36. 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

37. <<<***>>>
[***Thank u***]
<<<***>>>