What are Arduino Libraries?

• Libraries are pre-written pieces of code that extend the functionality of your Arduino sketches.
• They help you work with sensors, displays, motors, communication modules, and other hardware easily—without writing everything from scratch.
• Libraries include functions, classes, and examples that simplify coding.

✅ Example: To control an LCD display, instead of writing low-level code, you can use theLiquidCrystal library.

🔹 2. Types of Arduino Libraries

🔹 3. How to Use a Library

✅ Step 1: Include the Library in Your Sketch

Use#include <LibraryName.h> at the beginning of your code.

#include <Servo.h> // Include the Servo motor library

✅ Step 2: Use the Functions Provided

Example using the Servo library:

#include <Servo.h>

Servo myServo;

void setup() {

  myServo.attach(9);  // Connect servo to pin 9

}

void loop() {

  myServo.write(90);  // Rotate to 90 degrees

  delay(1000);

  myServo.write(0);   // Rotate to 0 degrees

  delay(1000);

}

🔹 4. How to Install a Library

There are 3 common methods to install libraries in Arduino IDE:

✅ Method 1: Using Library Manager (Recommended)

🔧 Steps:

1. Open Arduino IDE
2. Go to Sketch > Include Library > Manage Libraries
3. The Library Manager window will open
4. Search for the desired library (e.g., DHT sensor)
5. Click Install

📌 Example: Search forDHT sensor library and install it to use DHT11/DHT22 sensors.

✅ Method 2: Installing ZIP Library

If you have a.zip file of the library (from GitHub or other sources):

🔧 Steps:

1. Download the.zip file of the library
2. Open Arduino IDE
3. Go to Sketch > Include Library > Add .ZIP Library
4. Select the downloaded.zip file
5. Library will be added automatically

✅ Method 3: Manual Installation

If you want to install a library manually:

🔧 Steps:

1. Download and extract the library folder (should contain.h and.cpp files)
2. Move it to:

Documents > Arduino > libraries

3. Restart Arduino IDE

✅ After restart, go to Sketch > Include Library, and you should see your library listed.

🔹 5. How to Upload a Sketch Using a Library

Once a library is included:

• Just write your code using the library functions
• Connect your Arduino board
• Click Verify✅ to check for errors
• Click Upload🔼 to send the code to the board

🔹 6. Commonly Used Libraries in Arduino

🔹 7. Troubleshooting Library Issues

Real-life Example: DHT11 Sensor Code Using Library

#include "DHT.h"      // Include the DHT sensor library

#define DHTPIN 2      // Sensor data pin connected to Arduino pin 2

#define DHTTYPE DHT11 // DHT11 sensor type

DHT dht(DHTPIN, DHTTYPE);

void setup() {

  Serial.begin(9600);

  dht.begin();       // Start the sensor

}

void loop() {

  float h = dht.readHumidity();     // Read humidity

  float t = dht.readTemperature();  // Read temperature

  Serial.print("Humidity: ");

  Serial.print(h);

  Serial.print("%  | Temperature: ");

  Serial.print(t);

  Serial.println("°C");

  delay(2000);

}

Summary