Lesson 4 – Task 2

Controlling LED Timing with delay() | Task 2

Control LED timing using delay()

Now that your traffic light circuit is ready, it's time to write the code to control it.

In the example below, the green LED stays on for 5 seconds, the yellow for 1.5 seconds, and the red for 5 seconds. This timing is controlled using the delay() function in milliseconds.

        
// Lesson 4 Traffic light

int greenLed = 5;
int yellowLed = 6;
int redLed = 7;

int dtGreen = 5000;
int dtYellow = 1500;
int dtRed = 5000;

int val;

void setup() {
  // put your setup code here, to run once:
pinMode(greenLed, OUTPUT);
pinMode(yellowLed, OUTPUT);
pinMode(redLed, OUTPUT);
Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
digitalWrite(greenLed, HIGH);
Serial.println("green");
delay(dtGreen);
digitalWrite(greenLed, LOW);

digitalWrite(yellowLed, HIGH);
Serial.println("yellow");
delay(dtYellow);
digitalWrite(yellowLed, LOW);

digitalWrite(redLed, HIGH);
Serial.println("red");
delay(dtRed);
digitalWrite(redLed, LOW);
}

💡 Remember: 1000 milliseconds = 1 second.

Write the sketch in your Arduino IDE and upload it to test your traffic light code.