Best Sensors for Arduino Projects: Complete Guide with 15 Project Ideas

Getting Started with Arduino Sensors

Sensors allow your Arduino to perceive the world - temperature, distance, light, motion, and more. This guide covers the most popular sensors with wiring diagrams and code examples.

Temperature & Humidity: DHT22

The DHT22 (AM2302) is a reliable, affordable sensor for temperature and humidity measurements.

#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

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

void loop() {
 float h = dht.readHumidity();
 float t = dht.readTemperature();
 
 Serial.print("Temp: "); Serial.print(t); Serial.print("°C ");
 Serial.print("Humidity: "); Serial.print(h); Serial.println("%");
 delay(2000);
}

Distance: HC-SR04 Ultrasonic

The HC-SR04 measures distance using ultrasonic pulses (like sonar). Range: 2cm to 400cm.

#define TRIG_PIN 9
#define ECHO_PIN 10

void setup() {
 Serial.begin(9600);
 pinMode(TRIG_PIN, OUTPUT);
 pinMode(ECHO_PIN, INPUT);
}

void loop() {
 // Send pulse
 digitalWrite(TRIG_PIN, LOW);
 delayMicroseconds(2);
 digitalWrite(TRIG_PIN, HIGH);
 delayMicroseconds(10);
 digitalWrite(TRIG_PIN, LOW);
 
 // Measure echo time
 long duration = pulseIn(ECHO_PIN, HIGH);
 float distance = duration * 0.034 / 2; // cm
 
 Serial.print("Distance: ");
 Serial.print(distance);
 Serial.println(" cm");
 delay(100);
}

Light: LDR (Photoresistor)

An LDR changes resistance based on light intensity. Use with a voltage divider to read analog values.

#define LDR_PIN A0

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

void loop() {
 int lightValue = analogRead(LDR_PIN);
 
 Serial.print("Light: ");
 Serial.print(lightValue);
 
 if (lightValue < 200) {
 Serial.println(" (Dark)");
 } else if (lightValue < 600) {
 Serial.println(" (Dim)");
 } else {
 Serial.println(" (Bright)");
 }
 delay(500);
}

Project Ideas

Common Sensors Reference