Arduino LED Chaser – Running Light Project for Beginners

Introduction

An LED Chaser (also called a "Running Light") is a circuit where multiple LED's turn on and off one after the other to create a chasing effect. In this guide, we will use an Arduino Uno to control four LED's connected to Digital Pins 13, 12, 11, and 10.

🛠️ Components Needed

• Arduino Uno R3

• 4 LEDs (Red)

• 1 Resistor (220Ω or 330Ω)

• Jumper Wires & Breadboard

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🔌 Circuit and Connections

To keep the wiring simple, all LED's share a single ground connection through one resistor:

• Anodes (Long Legs): Connect to Arduino Digital Pins 13, 12, 11, and 10.

• Cathodes (Short Legs): All connected together to a single ground rail on your breadboard.

• Ground: The shared cathode rail connects to the Resistor, which then connects to the Arduino GND pin.

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💻 Arduino Code

Copy and paste this code into your Arduino IDE to start the chaser:

void setup() {

  // Set pins 10, 11, 12, and 13 as outputs

  pinMode(13, OUTPUT);

  pinMode(12, OUTPUT);

  pinMode(11, OUTPUT);

  pinMode(10, OUTPUT);

}

void loop() {

  // Move forward from pin 13 to 10

  for (int pin = 13; pin >= 10; pin--) {

    digitalWrite(pin, HIGH); // Turn LED on

    delay(200);              // Wait 0.2 seconds

    digitalWrite(pin, LOW);  // Turn LED off

  }

}

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🔌 Circuit Explanation: The "Ground Rail" Method

In this specific circuit, we are using a Common Resistor setup. This is a very clever way to save space on a breadboard!

• The Positive Side (Control): Each LED is connected to its own Digital Pin ($13,12,11,10$). These pins act like individual power switches. When the code says HIGH, the "switch" closes, and 5V flows to that specific LED.

• The Negative Side (Return): All the short legs (Cathodes) are tied together. This is called a "Common Ground."

• The Resistor's Job: Instead of 4 resistors, we use one $220\Omega$ resistor between the common ground and the Arduino GND pin. Since our code only turns on one LED at a time, that single resistor is enough to protect whichever LED is currently lit.

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💻 Code Explanation: The "For Loop" Magic

Instead of writing digitalWrite many times, we use a For Loop. This makes the code shorter and more professional.

1. The Setup void setup() The loop for (int pin = 10; pin <= 13; pin++) tells the Arduino: "Start at pin 10, and as long as the number is less than or equal to 13, set that pin as an OUTPUT." It’s a fast way to initialize all pins at once.

2. The Main Loop void loop()

• HIGH: Sends 5 V to the pin, lighting the LED.

• Delay (1000 ms): Keeps the light on for 1 seconds so the human eye can see the movement.

• LOW: Cuts the power to 0 V, turning the LED off before the loop moves to the next pin.

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💡 Pro-Tips for Your Readers

• Speed Control: Change the delay(1000) to 100 for a faster chase, or 500 for more slower one.

• Resistor Safety: While sharing one resistor works for this chaser, it is better practice in larger projects (where multiple LED's stay on) to give each LED its own resistor.

• Reverse Direction: Can you modify the code to make the lights "bounce" back and forth?