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What are Libraries?

Libraries are pre-written code that add functionality to your Arduino. Install via: Sketch → Include Library → Manage Libraries.

Servo Motor Control

#include <Servo.h>

Servo myServo;

void setup() {
    myServo.attach(9);  // Servo on pin 9
}

void loop() {
    for (int angle = 0; angle <= 180; angle++) {
        myServo.write(angle);  // Move to angle
        delay(15);
    }
    for (int angle = 180; angle >= 0; angle--) {
        myServo.write(angle);
        delay(15);
    }
}

LCD Display (LiquidCrystal)

#include <LiquidCrystal.h>

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

void setup() {
    lcd.begin(16, 2);           // 16 columns, 2 rows
    lcd.print("Hello World!");
}

void loop() {
    lcd.setCursor(0, 1);       // Column 0, Row 1
    lcd.print("Time: ");
    lcd.print(millis() / 1000);
    lcd.print("s   ");
    delay(500);
}

DHT Temperature & Humidity Sensor

#include <DHT.h>

#define DHTPIN 2
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

void setup() {
    Serial.begin(9600);
    dht.begin();
}

void loop() {
    float temp = dht.readTemperature();
    float humidity = dht.readHumidity();

    Serial.print("Temp: ");   Serial.print(temp);   Serial.println(" °C");
    Serial.print("Humidity: "); Serial.print(humidity); Serial.println(" %");
    delay(2000);
}

✅ Quick Quiz

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