📘 Project 1 – LED Blinking (Hello World of Arduino)

🎯 Learning Objectives

After completing this project, students will be able to:

✅ Connect an LED with Arduino

✅ Understand digital output

✅ Use pinMode()

✅ Use digitalWrite()

✅ Use delay()

✅ Upload Arduino programs

1. Introduction

The LED Blinking project is the first project for almost every Arduino programmer.

Just like printing:

Hello World

is the first program in many programming languages,

blinking an LED is the first Arduino project.

This project teaches the basic workflow of Arduino programming.

2. What is an LED?

LED stands for:

Light Emitting Diode

An LED emits light when electric current flows through it.

LED Legs

LED has two terminals:

Anode (+)

Long Leg

Cathode (-)

Short Leg

3. Components Required

4. Circuit Connection

Connection Diagram

Arduino Pin 13
      |
    220Ω
      |
     LED
      |
     GND

5. Working Principle

Arduino sends:

HIGH

↓

LED ON

Arduino sends:

LOW

↓

LED OFF

By repeating ON and OFF with delays, the LED appears to blink.

6. Algorithm

Step 1

Set Pin 13 as OUTPUT

↓

Step 2

Turn LED ON

↓

Step 3

Wait 1 Second

↓

Step 4

Turn LED OFF

↓

Step 5

Wait 1 Second

↓

Step 6

Repeat Forever

7. Arduino Program

void setup()
{
  pinMode(13, OUTPUT);
}

void loop()
{
  digitalWrite(13, HIGH);

  delay(1000);

  digitalWrite(13, LOW);

  delay(1000);
}

8. Code Explanation

Configure Pin

pinMode(13, OUTPUT);

Makes Pin 13 an output pin.

LED ON

digitalWrite(13, HIGH);

Outputs 5V.

LED glows.

Delay

delay(1000);

Waits:

1000 ms = 1 Second

LED OFF

digitalWrite(13, LOW);

Outputs 0V.

LED turns OFF.

Repeat

The loop() function repeats forever.

9. Expected Output

LED Pattern:

ON
↓
1 Second
↓
OFF
↓
1 Second
↓
Repeat

10. Real World Applications

LED blinking concepts are used in:

• Status Indicators
• Alarm Systems
• Traffic Signals
• Machine Status Lights
• Industrial Control Panels

11. Common Errors

LED Not Glowing

Check:

• LED polarity
• Pin number
• Wiring

LED Always ON

Check:

digitalWrite()

logic.

Upload Failed

Check:

• COM Port
• USB Cable
• Board Selection

12. Experiment Variations

Fast Blink

delay(200);

Slow Blink

delay(2000);

SOS Pattern

Create custom blinking sequences.

📊 Project Summary

In this project, we learned:

✅ LED connection

✅ Digital Output

✅ pinMode()

✅ digitalWrite()

✅ delay()

✅ Arduino program upload

This project serves as the foundation for all future Arduino projects.

🏠 Assignment

Task 1

Change blink speed to 500 ms.

Task 2

Change blink speed to 200 ms.

Task 3

Create a pattern:

ON
ON
OFF
ON
OFF
OFF

Task 4

Connect two LEDs and blink them alternately.

Task 5

Explain the role of pinMode(), digitalWrite(), and delay() in your own words.