Tutorial 2: LED Basics – How Light Emitting Diodes Work with Arduino

Tutorial 2: LED Basics – How Light Emitting Diodes Work with Arduino

Welcome back to CraftedTech Engineering’s Arduino tutorial series!
In this lesson, we’ll teach you how to properly wire and control a single LED with your Arduino. Understanding how LEDs work is a must for any beginner looking to master electronics and microcontrollers.

What You’ll Need

  • 1 Arduino Board (e.g., Arduino UNO)
  • 1 LED (any color)
  • 1 220Ω Resistor
  • Breadboard
  • Jumper wires
  • USB Cable for Arduino

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What Is an LED and How Does It Work?

An LED (Light Emitting Diode) is a component that lights up when current flows through it — but only in one direction. It has two legs:

  • Anode (long leg) = Positive side
  • Cathode (short leg) = Negative side

To prevent damage, a resistor is used to limit the current going to the LED.

Step-by-Step Instructions

Step 1: Wire the Circuit

  1. Insert the LED into the breadboard
  2. Connect the anode (long leg) to digital pin 9 on the Arduino using a jumper wire
  3. Connect the cathode (short leg) to one end of a 220Ω resistor
  4. Connect the other end of the resistor to GND on the Arduino

Step 2: Upload This Code

void setup() {
  // Set pin 9 as output
pinMode(9, OUTPUT);
}

void loop() {
  digitalWrite(ledPin, HIGH);  // Turn LED on
  delay(1000);                 // Wait 1 second
  digitalWrite(ledPin, LOW);   // Turn LED off
  delay(1000);                 // Wait 1 second


Code Breakdown

  • pinMode(ledPin, OUTPUT);: Configures pin 9 to send signals
  • digitalWrite(ledPin, HIGH);: Sends voltage to light up the LED
  • digitalWrite(ledPin, LOW);: Stops voltage and turns off the LED
  • delay(1000);: Pauses the program for 1 second

Try This!

  • Change delay(1000) to delay(200) for faster blinking
  • Try other pins like pin 7 or 8, just update ledPin in the code
  • Use a different resistor value (e.g., 330Ω or 470Ω) and observe brightness changes

Troubleshooting Tips

  • LED not lighting up? Double-check the LED orientation (long leg = pin)
  • Still no luck? Try another LED — it may be burnt out
  • Resistor issue? Using too high a value may make the LED too dim
  • Try changing ports and re-uploading the sketch if nothing happens

What You Learned in This Tutorial

✔️ How to wire a single LED to your Arduino
✔️ How to use a resistor to protect components
✔️ How to write code to blink the LED
✔️ How to apply digitalWrite() and delay() functions

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