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DHT22 Temperature and Humidity Meter

A project that measures humidity and temperature, in both Celsius and Fahrenheit, with a DHT22 sensor and writes them to the Serial Monitor every two seconds. It is more precise than the DHT11 and has a wider measuring range. Before uploading the code, install Adafruit's "DHT sensor library" in the Arduino IDE (and the "Adafruit Unified Sensor" library it asks for).

What you need

• 1 × Arduino Uno R3
• 1 × DHT22 Temperature/Humidity Sensor (AM2302)
• 3 × Jumper Wire - Male/Female

Wiring steps

1. 1

   Power the sensor

   

   Plug a red jumper wire into the 5V pin on the Arduino's POWER header. With the DHT22's front facing you, connect the other end to its top pin, pin 1 (VCC).

2. 2

   Connect the data line

   

   Plug a blue jumper wire into the Arduino's digital pin 2. Connect its other end to the DHT22's pin 2 (DATA), just below. The code reads the sensor on this pin (DHTPIN 2).

3. 3

   Ground (GND) connection

   

   Plug a black jumper wire into the GND pin on the Arduino's digital header, next to pin 13. Connect its other end to the DHT22's bottom pin, pin 4 (GND). Pin 3 stays free; do not connect anything to it.

Arduino sketch

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

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin(); // initialize the sensor
}

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

  // read humidity
  float humi  = dht.readHumidity();
  // read temperature as Celsius
  float tempC = dht.readTemperature();
  // read temperature as Fahrenheit
  float tempF = dht.readTemperature(true);

  // check if any reads failed
  if (isnan(humi) || isnan(tempC) || isnan(tempF)) {
    Serial.println("Failed to read from DHT sensor!");
  } else {
    Serial.print("Humidity: ");
    Serial.print(humi);
    Serial.print("%");

    Serial.print("  |  ");

    Serial.print("Temperature: ");
    Serial.print(tempC);
    Serial.print("°C ~ ");
    Serial.print(tempF);
    Serial.println("°F");
  }
}

What the Serial Monitor shows

Humidity: 45.50%  |  Temperature: 23.40°C ~ 74.12°F
Humidity: 45.60%  |  Temperature: 23.40°C ~ 74.12°F