DHT11 Temperature and Humidity Sensor

Name: DHT11 Temperature and Humidity Sensor
Brand: ESP32
Price: 2 USD
Availability: InStock

DHT11 Temperature and Humidity Sensor image

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Overview

The DHT11 is a low-cost digital sensor for measuring temperature and humidity. It provides calibrated digital outputs and is easy to interface with microcontrollers. With a temperature measurement range of 0-50°C and humidity range of 20-90%, it's suitable for basic environmental sensing applications.

Quick Navigation

📋 Specs 📍 Pinout 🔌 Wiring 🔧 Debug

Code Examples

Arduino

C++ Framework

ESP-IDF

Native Framework

ESPHome

YAML Configuration

PlatformIO

IDE & Toolchain

MicroPython

Python Framework

About DHT11 Temperature and Humidity Sensor

The DHT11 is a basic, ultra low-cost digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and outputs a digital signal on the data pin (no analog input pins needed). It’s fairly simple to use, but requires careful timing to grab data. The only real downside of this sensor is you can only get new data from it once every 2 seconds.

Where to Buy

Get Your DHT11

Starting from

$2 per unit

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Technical Specs

DHT11 Specifications

Complete technical specification details for DHT11 Temperature and Humidity Sensor

📊 Technical Parameters

Interface Single-Wire Digital

Temperature Range 0°C to 50°C

Humidity Range 20% to 90% RH

Temperature Accuracy ±2°C

Humidity Accuracy ±5% RH

Operating Voltage 3.3V to 5.5V

Sampling Rate Once every 2 seconds

Download Full Datasheet

Pin Configuration

DHT11 Pinout

The DHT11 features a simple 4-pin design for power and single-wire digital communication.

Visual Pinout Diagram

Pinout Diagram Primary

DHT11 Temperature and Humidity Sensor pinout

Total Pins

Pin Types

Power

Communication

Control

Quick Tips

🔌

Sensor uses single-wire digital interface,⚠️ Requires 10kΩ pull-up resistor on DATA pin

💡

Works with both 3.3V and 5V power supplies

⏱️

Sampling rate limited to once per second

Pin Descriptions

Pin Name	Type	Description	Notes
1 VCC	Power	Power supply input (3.3V or 5V)	Compatible with both 3.3V and 5V logic levels
2 DATA	Communication	Digital signal output	Connect to any digital GPIO pin on microcontroller
3 NC	Control	Not connected	Leave this pin unconnected
4 GND	Power	Ground connection	Connect to ESP32 ground

Connection Guide

Wiring DHT11 to ESP32

Connect the DHT11 using the single-wire digital interface with a pull-up resistor for reliable communication.

Visual Wiring Diagram

Wiring Diagram Recommended

DHT11 Temperature and Humidity Sensor wiring with ESP32

Connections

Connection Status

Required

Protocol

OneWire

Pin Connections

DHT11 Pin	ESP32 Pin	Description
1 VCC Required	3.3V	Power supply (can use 3.3V or 5V)
2 GND Required	GND	Ground connection
3 DATA Required	GPIO4	Digital data line
4 DATA (Pull-up) Required	10kΩ to VCC	Pull-up resistor for reliable communication

💡

GPIO4 is commonly used but any GPIO pin works

🔧

10kΩ pull-up resistor between DATA and VCC is required

⚡

Use 3.3V for ESP32 compatibility, 5V also works

⏱️

Wait at least 2 seconds between readings

Help & Support

DHT11 Troubleshooting

Common issues and solutions to help you get your sensor working

Common Issues

Debugging Tips

Additional Resources

Datasheet

Technical specifications and guidelines

Code Examples

DHT11 Programming Examples

Ready-to-use code examples for different platforms and frameworks

#include "DHT.h"

#define DHTPIN 4 // Digital pin connected to the DHT sensor
#define DHTTYPE DHT11 // DHT11 sensor type

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  Serial.println("DHT11 Sensor Initialization");
  dht.begin();
}

void loop() {
  delay(2000); // Wait a few seconds between measurements

  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

  if (isnan(humidity) || isnan(temperature)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }

  Serial.print("Humidity: ");
  Serial.print(humidity);
  Serial.print("%  Temperature: ");
  Serial.print(temperature);
  Serial.println("°C");
}

This Arduino sketch interfaces with the DHT11 sensor to read temperature and humidity data. It utilizes the DHT library to communicate with the sensor. The setup() function initializes serial communication and the sensor. In the loop() function, it waits for 2 seconds between measurements, reads humidity and temperature, checks for successful readings, and then prints the values to the Serial Monitor.

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/gpio.h"

#define DHT11_PIN GPIO_NUM_4

void dht11_task(void *pvParameter) {
    // DHT11 reading logic here
    while (1) {
        // Read temperature and humidity
        // Print values
        vTaskDelay(2000 / portTICK_PERIOD_MS); // Delay for 2 seconds
    }
}

void app_main() {
    xTaskCreate(&dht11_task, "dht11_task", 2048, NULL, 5, NULL);
}

This ESP-IDF code sets up a FreeRTOS task to read data from the DHT11 sensor connected to GPIO 4. The dht11_task function contains the logic to read temperature and humidity from the sensor and print the values. The task runs in an infinite loop with a 2-second delay between readings. The app_main function creates this task with a stack size of 2048 bytes and a priority of 5.

sensor:
  - platform: dht
    model: DHT11
    pin: GPIO4
    temperature:
      name: "Living Room Temperature"
    humidity:
      name: "Living Room Humidity"
    update_interval: 60s

This ESPHome configuration specifies the dht platform and sets the model to DHT11 for correct handling of the sensor. The pin key defines the GPIO pin (e.g., GPIO4) to which the sensor's data pin is connected. The temperature and humidity keys define the sensor outputs, giving user-friendly names like 'Living Room Temperature' and 'Living Room Humidity.' The update_interval is set to 60 seconds, which means the ESP32 will read and update the sensor data every 60 seconds.

platformio.ini

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps = 
    adafruit/DHT sensor library @ ^1.4.3
    adafruit/Adafruit Unified Sensor @ ^1.1.6
monitor_speed = 115200

main.cpp

#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>

#define DHTPIN 4 // Define the GPIO pin for the data pin
#define DHTTYPE DHT11 // Specify the DHT model

DHT dht(DHTPIN, DHTTYPE);

void setup() {
    Serial.begin(115200);
    Serial.println("DHT11 Sensor Example");

    // Initialize the sensor
    dht.begin();
}

void loop() {
    // Read temperature and humidity
    float temperature = dht.readTemperature();
    float humidity = dht.readHumidity();

    // Check if any readings failed
    if (isnan(temperature) || isnan(humidity)) {
        Serial.println("Failed to read from DHT sensor!");
        return;
    }

    // Print results to Serial Monitor
    Serial.print("Temperature: ");
    Serial.print(temperature);
    Serial.println(" °C");

    Serial.print("Humidity: ");
    Serial.print(humidity);
    Serial.println(" %");

    delay(2000); // Wait before next reading
}

The platform = espressif32 specifies that the project is for ESP32 boards, and board = esp32dev sets the specific development board being used. The lib_deps field includes the required libraries for the DHT11 sensor (DHT sensor library and Adafruit Unified Sensor), ensuring compatibility. The code defines the GPIO pin (e.g., GPIO4) for the sensor’s data line and initializes the DHT11 sensor using the DHT library. Temperature and humidity readings are printed to the Serial Monitor every 2 seconds, with error handling to check for invalid readings.

from machine import Pin
from time import sleep
import dht

# Initialize the DHT11 sensor on GPIO4
dht_sensor = dht.DHT11(Pin(4))

print("DHT11 Sensor Example")

while True:
    try:
        # Measure temperature and humidity
        dht_sensor.measure()
        temperature = dht_sensor.temperature()  # Temperature in Celsius
        humidity = dht_sensor.humidity()  # Relative Humidity in %

        # Print temperature and humidity to the console
        print("Temperature: {:.1f} °C".format(temperature))
        print("Humidity: {:.1f} %".format(humidity))
    except OSError as e:
        print("Failed to read sensor.")

    # Delay between readings
    sleep(2)

The dht module simplifies interactions with the DHT11 sensor, handling initialization and data retrieval. The sensor is initialized with the GPIO pin (e.g., GPIO4), and a confirmation message is printed to indicate successful setup. Inside an infinite loop, the script continuously reads the temperature (in Celsius) and relative humidity (in percentage) using the measure() method. The readings are formatted and printed to the console. Error handling with try and except ensures the program can recover from sensor read failures. A 2-second delay between readings ensures manageable updates.

Summary

Wrapping Up DHT11

The ESP32 DHT11 Temperature and Humidity Sensor is a powerful environment sensor that offers excellent performance and reliability. With support for multiple development platforms including Arduino, ESP-IDF, ESPHome, PlatformIO, and MicroPython, it's a versatile choice for your IoT projects.