Electorials Electronics
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Project 005: Arduino "DHT" Humidity Sensor Project

A simple project for any electronic hobbyist interested in weather-related projects with the help of an Arduino and a "DHT" humidity sensor.

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Project 005: Arduino "DHT" Humidity Sensor Project

Things used in this project

Hardware components

Arduino UNO
Arduino UNO
You could use any other Arduino board as well. The Keyestudio Uno is used in this example.
×1
DHT22 Temperature Sensor
DHT22 Temperature Sensor
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Jumper wires (generic)
Jumper wires (generic)
3 Male to Male Jumper Wires.
×3
Resistor 10k ohm
Resistor 10k ohm
×1
Breadboard (generic)
Breadboard (generic)
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USB-A to B Cable
USB-A to B Cable
Depends on the Arduino.
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NextPCB
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Software apps and online services

Arduino IDE
Arduino IDE

Story

Read more

Schematics

Circuit Diagram

Schematics

Code

Arduino "DHT" Humidity Sensor Project Code

C/C++
// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain
#include "DHT.h"
#define DHTPIN 2     // what digital pin we're connected to

// Uncomment whatever type you're using!

//#define DHTTYPE DHT11   // DHT 11

//#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321

//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V

// NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1
// to 3.3V instead of 5V!

// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

// Initialize DHT sensor.

// Note that older versions of this library took an optional third parameter to
// tweak the timings for faster processors.  This parameter is no longer needed
// as the current DHT reading algorithm adjusts itself to work on faster procs.

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  Serial.println("DHTxx test!");
  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);
  // Reading temperature or humidity takes about 250 milliseconds!
  // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
  float h = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float t = dht.readTemperature();
  // Read temperature as Fahrenheit (isFahrenheit = true)
  float f = dht.readTemperature(true);
  // Check if any reads failed and exit early (to try again).
  if (isnan(h) || isnan(t) || isnan(f)) {
    Serial.println("Failed to read from DHT sensor!");
    return;
  }
  
  // Compute heat index in Fahrenheit (the default)
  float hif = dht.computeHeatIndex(f, h);
  // Compute heat index in Celsius (isFahreheit = false)
  float hic = dht.computeHeatIndex(t, h, false);
  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.print(" *C ");
  Serial.print(f);
  Serial.print(" *F\t");
  Serial.print("    Heat index: ");
  Serial.print(hic);
  Serial.print(" *C ");
  Serial.print(hif);
  Serial.println(" *F");
}

Adafruit DHT Sensor Library

Credits go to Adafruit for their amazing library, compatible for the DHT11, DHT22 and DHT21 humidity sensors.

Credits

Electorials Electronics
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