8/3/2019 Synchronized Traffic Signal Controller

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SYNCHRONIZED TRAFFIC SIGNAL CONTROLLER

1- This controller assumes equal traffic density on the entire road.2- This traffic controller uses digital

logic, which can be easily, isimplemented by logic gates.3- This controller is generalized one can be used

for different roads withslight modification.4- All the traffic signals in this controller are synchronized

with each other.X, Y are used as binary variables to denote the four states of all thesignals. Letters A to Hindicate the left and right sides of roads in four

directions as shown in the fig. And the traffic movement on the roads at a specific signal (green)

isdenoted by arrows in directions in which traffic can flow as shown in figure.When one signal is green

the other signals, one will be yellow from whichdirection traffic will flow after it and other two will be

red.The Boolean function of green light of a signal will be same as the Booleanfunction of yellow light of

the other signal through which traffic will flow after it signal and the other two red lights of remaining

signals and it will be sameas for other paths.

IMPLEMENTATION:-.Timer 555 (IC1) is wired as an astable multivibrator to generate clock signalfor the

4-bit counter 74160 (IC2). The time duration of IC1 can be adjustedby varying the value of resistor R1,

resistor R2, or capacitor C2 of the clockcircuit. Theon time duration T is given by the following

relationship:T = 0.695C2(R1+R2)

IC2 is wired as a 2-bit binary counter by connecting its pin 11s output toclear pin 1 via inverter. Binary

outputs from pins 13, 14 assumed asvariables X and Y, respectively. These outputs, along with

their complimentary outputs X, Y respectively, are used as inputs to the rest of the logic circuit to

realize various outputs satisfying Table 1. Pin 12 isgrounded because we require two bit counter so to

convert it into 2 bitcounter. We inverted pin 11s output and set it to clear input of counter

andgrounded pin 12.We can simulate various traffic lights using green, yellow, and red LEDsand feed the

outputs of the circuit.The traffic signals can also be controlled manually, if desired. Any signalstate can

be established by entering the binary value corresponding to thatparticular state into the parallel input

pins of the 2-bit counter. Similarly, thesignal can be reset at any time by providing logic 0 at the reset pin

(pin 1)of the counter using an external switch

Equipment:-1- 555 timer IC

2- 74160 counter IC

3- Capacitors

4- Resistors

5- 7404 inverter IC

6- 7408 AND IC

7- LEDS (green,yellow,red)

BOOLEAN FUNCTIONS FOR ALL THE SIGNAL CONDITIONS:-