Arduino Code Library

A collection of tested and verified Arduino code snippets for your projects. Copy, modify, and learn from these examples.

ServoLDRSensorAutomation
Intermediate

Automatic Switch with LDR Sensor

An Arduino sketch that automatically controls a servo motor based on light levels detected by an LDR sensor, with buzzer feedback.

Shaun Sosi
#include <Servo.h>

// Pin definitions and global variables
const int WAIT_TIME = 500;
const int LDR_PIN = A0;
const int SERVO_PIN = 6;
const int BUZZER_PIN = 8;

int ldrValue;
int servoPosition;
int mode = 2;  // Initial mode

Servo servo;

void setup() {
  // Initialize pins and serial communication
  servo.attach(SERVO_PIN);
  pinMode(LDR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  Serial.begin(9600);
}

void loop() {
  // Read light sensor value
  ldrValue = analogRead(LDR_PIN);
  Serial.println(ldrValue);

  // Check for high light level (mode 2 to 1)
  if (ldrValue >= 500 && mode == 2) {
    // Move servo and give feedback
    servo.write(500);
    delay(400);
    servo.write(90);
    
    // Buzzer feedback
    digitalWrite(BUZZER_PIN, HIGH);
    delay(WAIT_TIME);
    digitalWrite(BUZZER_PIN, LOW);
    
    mode = 1;
  }

  // Check for low light level (mode 1 to 2)
  if (ldrValue <= 400 && mode == 1) {
    // Move servo and give feedback
    servo.write(0);
    delay(400);
    servo.write(90);
    
    // Buzzer feedback
    digitalWrite(BUZZER_PIN, HIGH);
    delay(WAIT_TIME);
    digitalWrite(BUZZER_PIN, LOW);
    delay(WAIT_TIME);
    
    mode = 2;
  }
}