How can you make 3 LEDs blink like traffic lights (Red, Yellow, Green)?

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To make 3 LEDs blink like traffic lights (Red, Yellow, Green), you’ll need to follow a simple sequence of turning each LED on and off in a timed pattern. Below is an example of how to implement this using a basic microcontroller (such as an Arduino), assuming you have three LEDs connected to three pins on the microcontroller.

Components Needed:

  • 3 LEDs (Red, Yellow, Green)
  • 3 resistors (typically 220Ω to 330Ω for each LED)
  • Arduino or any microcontroller
  • Jumper wires and breadboard

Circuit Setup:

  1. Connect each LED’s anode (long leg) to the respective pin on the microcontroller (e.g., pin 2 for Red, pin 3 for Yellow, pin 4 for Green).
  2. Connect the cathode (short leg) of each LED to the ground (GND) of the microcontroller through a current-limiting resistor.
  3. Ensure that the pins are set as output in your code.

Arduino Code:

// Define the LED pins
int redPin = 2;
int yellowPin = 3;
int greenPin = 4;

void setup() {
  // Set the LED pins as output
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
}

void loop() {
  // Red LED ON, Yellow and Green OFF
  digitalWrite(redPin, HIGH);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, LOW);
  delay(1000); // Wait for 1 second

  // Yellow LED ON, Red and Green OFF
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, HIGH);
  digitalWrite(greenPin, LOW);
  delay(1000); // Wait for 1 second

  // Green LED ON, Red and Yellow OFF
  digitalWrite(redPin, LOW);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, HIGH);
  delay(1000); // Wait for 1 second
}

How it works:

  1. The code sets each LED pin as an output.
  2. In the loop() function, the LEDs are turned on one at a time to simulate the traffic light sequence:
    • Red LED stays on for 1 second.
    • Yellow LED stays on for 1 second (this mimics the “warning” light).
    • Green LED stays on for 1 second.
  3. This sequence repeats indefinitely.

Traffic Light Timing:

  • Red Light: 1 second
  • Yellow Light: 1 second
  • Green Light: 1 second

You can adjust the timing (using the delay() function) depending on how fast or slow you want the traffic lights to change.

This simple code creates a basic traffic light pattern for the LEDs, simulating the transitions of red, yellow, and green lights.