Arduino based traffic light demonstration

In Arduino based traffic light demonstration tutorial, we’ll learn to implement a simple traffic light system using some led’s, resistors, and Arduino. Traffic light Sequence will change after every 4 seconds.

Materials required:

Arduino uno
ULN2803 (NPN darlington pair)
Red, Green, Yellow Led’s
330 ohms resistors

Source code

Copy

	#define r1 1
	#define y1 2
	#define g1 3
	#define r2 4
	#define y2 5
	#define g2 6
	#define r3 7
	#define y3 8
	#define g3 9
	#define r4 10
	#define y4 11
	#define g4 12
	int ledPins[] = { 1,2,3,4,5,6,7,8,9,10,11,12};
	int pinCount = 12;
	void setup()
	{
	for (int thisPin = 0; thisPin < pinCount; thisPin++) {
	pinMode(ledPins[thisPin], OUTPUT);
	}
	}
	void loop()
	{
	digitalWrite(r1, HIGH); +digitalWrite(r2, HIGH); digitalWrite(r3, HIGH); digitalWrite(r4, HIGH);
	digitalWrite(y1, HIGH); digitalWrite(y2, HIGH); digitalWrite(y3, HIGH); digitalWrite(y4, HIGH);
	digitalWrite(g1, HIGH); digitalWrite(g2, HIGH); digitalWrite(g3, HIGH); digitalWrite(g4, HIGH);
	delay(4000);
	digitalWrite(r1, HIGH); digitalWrite(r2, HIGH); digitalWrite(r3, HIGH); digitalWrite(r4, LOW);
	digitalWrite(y1, LOW); digitalWrite(y2, LOW); digitalWrite(y3, LOW); digitalWrite(y4, LOW);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, HIGH);
	delay(4000);
	digitalWrite(r1, HIGH); digitalWrite(r2, HIGH); digitalWrite(r3, LOW); digitalWrite(r4, LOW);
	digitalWrite(y1, LOW); digitalWrite(y2, LOW); digitalWrite(y3, HIGH); digitalWrite(y4, HIGH);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, HIGH); digitalWrite(r2, HIGH); digitalWrite(r3, LOW); digitalWrite(r4, HIGH);
	digitalWrite(y1, LOW); digitalWrite(y2, LOW); digitalWrite(y3, LOW); digitalWrite(y4, LOW);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, HIGH); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, HIGH); digitalWrite(r2, LOW); digitalWrite(r3, LOW); digitalWrite(r4, HIGH);
	digitalWrite(y1, LOW); digitalWrite(y2, HIGH); digitalWrite(y3, HIGH); digitalWrite(y4, LOW);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, HIGH); digitalWrite(r2, LOW); digitalWrite(r3, HIGH); digitalWrite(r4, HIGH);
	digitalWrite(y1, LOW); digitalWrite(y2, LOW); digitalWrite(y3, LOW); digitalWrite(y4, LOW);
	digitalWrite(g1, LOW); digitalWrite(g2,HIGH); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, LOW); digitalWrite(r2, LOW); digitalWrite(r3, HIGH); digitalWrite(r4, HIGH);
	digitalWrite(y1, HIGH); digitalWrite(y2, HIGH); digitalWrite(y3, LOW); digitalWrite(y4, LOW);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, LOW); digitalWrite(r2, HIGH); digitalWrite(r3, HIGH); digitalWrite(r4, HIGH);
	digitalWrite(y1, LOW); digitalWrite(y2, LOW); digitalWrite(y3, LOW); digitalWrite(y4, LOW);
	digitalWrite(g1, HIGH); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	digitalWrite(r1, LOW); digitalWrite(r2, HIGH); digitalWrite(r3, HIGH); digitalWrite(r4, LOW);
	digitalWrite(y1, HIGH); digitalWrite(y2, LOW); digitalWrite(y3, LOW); digitalWrite(y4, HIGH);
	digitalWrite(g1, LOW); digitalWrite(g2,LOW); digitalWrite(g3, LOW); digitalWrite(g4, LOW);
	delay(4000);
	}

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