Introduction

The DHT11 is a basic, low-cost digital temperature and humidity sensor with a built-in status LED. It provides adequate accuracy for most hobbyist projects and includes visual feedback through its indicator LED.

Key Features

Technical Specifications

Pin Configuration

Wiring with Arduino

// Basic Connections:
// VCC  → 5V (LED will light up)
// DATA → D2 (with 4.7KΩ pull-up to VCC)
// GND  → GND

Library Setup

1. Install the DHT sensor library by Adafruit
2. Include the library in your sketch:

   #include <DHT.h>

3. Initialize the sensor (note DHT11 type):

#define DHTPIN 2       // Digital pin
#define DHTTYPE DHT11  // DHT 11

DHT dht(DHTPIN, DHTTYPE);

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

Basic Example with LED Monitoring

#include <DHT.h>

#define DHTPIN 2
#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
  pinMode(LED_BUILTIN, OUTPUT); // Arduino's onboard LED
}

void loop() {
  // Blink Arduino LED when reading sensor
  digitalWrite(LED_BUILTIN, HIGH);
  
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  
  digitalWrite(LED_BUILTIN, LOW);
  
  if (isnan(h) || isnan(t)) {
    Serial.println("Sensor error!");
    delay(500); // Rapid blink on error
    digitalWrite(LED_BUILTIN, HIGH);
    delay(500);
    return;
  }
  
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print("%\tTemperature: ");
  Serial.print(t);
  Serial.println("°C");
  
  delay(2000); // Match DHT11's 1Hz sampling rate
}

LED Status Guide

Troubleshooting