DHT22 (AM2302) Digital Temperature & Humidity Sensor

Product Overview

The DHT22 (also branded AM2302) is a calibrated digital temperature and humidity sensor combining a capacitive polymer humidity sensing element with a precision NTC thermistor. It outputs fully calibrated digital signals over a single-wire (single-bus) interface, so a microcontroller only needs one GPIO pin to read both temperature and relative humidity.

Key Features

• Calibrated digital output for temperature and relative humidity
• Single-wire (single-bus) protocol, only one GPIO required
• Wide measurement range: -40°C to +80°C, 0–100% RH
• Accuracy: ±0.5°C temperature, ±2% RH humidity
• Resolution: 0.1°C and 0.1% RH
• Operating voltage: 3.3V–5V DC (5V recommended for long cable runs)
• Drop-in upgrade for DHT11 designs that need higher accuracy
• RoHS compliant; lead-free assembly compatible

Specifications

Wiring (4-pin module)

1. VCC → 3.3V or 5V (5V recommended for cables >1 m)
2. DATA → MCU GPIO (with 10 kΩ pull-up to VCC)
3. NC (not connected on the module)
4. GND → Ground

Typical Applications

• DIY weather stations and home weather logging
• HVAC climate monitoring and indoor air-quality nodes
• Greenhouse, mushroom farm and soil-climate projects
• IoT telemetry with ESP32 / ESP8266 / Raspberry Pi
• Arduino / MicroPython / PlatformIO teaching kits

Application note: the single-bus protocol is NOT Dallas 1-Wire. Use the DHT sensor library (Adafruit_DHT, DHT.h, or MicroPython dht class). Reading faster than every 2 seconds returns stale data.

// Arduino example
#include "DHT.h"
#define DHTPIN 2
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);
void setup() { Serial.begin(9600); dht.begin(); }
void loop() {
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  Serial.print(t); Serial.print(" °C  ");
  Serial.print(h); Serial.println(" %");
  delay(2000);
}