DHT22 Temperature & Humidity Sensor

What is the DHT22 Temperature & Humidity Sensor?

The DHT22 is a digital temperature and humidity sensor that’s a step up from the common DHT11. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air, and outputs a calibrated digital signal via a single-wire bus. You’ll get readings with better accuracy and a wider range than the DHT11, making it perfect for weather stations, greenhouse monitoring, or any project where you want reliable environmental data.

It comes as a small module with four pins, often with a built-in pull-up resistor, so you can interface it directly with a microcontroller’s digital input pin. Just note that it needs a bit of timing precision in your code — the communication protocol is custom and slightly timing-sensitive, but there are libraries available for most platforms to handle that for you.

Key Specifications

Pinout

Note: Pin numbering and labeling can vary between module manufacturers and revisions. Always double-check against the datasheet for your specific batch.

Common Use Cases

• Indoor weather stations and temperature/humidity monitors for your workshop or home.
• Greenhouse or plant terrarium automation — trigger fans or misters based on readings.
• Server room or electronics enclosure environmental logging.
• Smart HVAC control prototypes (e.g., turn on a heater when temperature drops).
• Data logging experiments for science fair or IoT projects.

Wiring Example

For the most common setup with an Arduino Uno, connect pin 1 (VCC) to the 5V rail, and pin 4 (GND) to ground. Connect pin 2 (DATA) to any digital I/O pin, for example Arduino pin D2. If your module doesn’t have an onboard pull-up resistor, add a 4.7 kΩ resistor between the DATA pin and VCC. That’s it — just power and one data wire, and you’re ready to read sensor values with a DHT22 library.

Tips and Gotchas

• Wait two seconds between readings. The DHT22’s maximum sampling rate is 0.5 Hz — if you try to read it too fast, the sensor will ignore you or return stale data.
• Mind the pull-up resistor. Some modules include one, others don’t. If your data line doesn’t have a 4.7 kΩ to 10 kΩ pull-up to VCC, communication will fail intermittently.
• Keep the sensor dry during soldering. The humidity sensing element is exposed and sensitive to heat and moisture — soldering the pins or cleaning with excessive water can damage it.
• Don’t rely on it for sub-second readings. The DHT22 is great for slow environmental logging, but it’s not suitable for real-time applications like wind speed measurement or fast HVAC control loops.

Now go wire it up and start measuring your world — happy making!

Tutorial

With the DHT22 sensor and a microcontroller, you can build temperature and humidity monitors, data loggers, weather stations, and HVAC control systems.

// Complete working sketch for DHT22 on Arduino Uno
#include <DHT.h>

#define DHTPIN 2
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  Serial.println(F("DHT22 test!"));
  dht.begin();
}

void loop() {
  delay(2000);
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  if (isnan(h) || isnan(t)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  Serial.print(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.println(F("°C"));
}

[env:uno]
platform = atmelavr
board = uno
framework = arduino
lib_deps =
    adafruit/DHT sensor library

// Complete working sketch for DHT22 on ESP32
#include <DHT.h>

#define DHTPIN 4
#define DHTTYPE DHT22

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(115200);
  Serial.println(F("DHT22 test on ESP32!"));
  dht.begin();
}

void loop() {
  delay(2000);
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  if (isnan(h) || isnan(t)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }
  Serial.print(F("Humidity: "));
  Serial.print(h);
  Serial.print(F("%  Temperature: "));
  Serial.print(t);
  Serial.println(F("°C"));
}

[env:esp32dev]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps =
    adafruit/DHT sensor library