How to Use DFrobot DHT22 Temperature & Humidity Sensor V2: Examples, Pinouts, and Specs

The DFRobot DHT22 Temperature & Humidity Sensor V2 is a reliable sensor module capable of measuring both temperature and humidity with high accuracy. It utilizes the DHT22 sensor, which is known for its long-term stability and calibration. This sensor is widely used in various applications such as weather stations, home environment monitoring, HVAC systems, and any project where precise atmospheric conditions are needed.

• Home automation systems
• Weather monitoring stations
• Environmental data logging
• HVAC system monitoring
• Agricultural and soil monitoring

• Operating Voltage: 3.3 to 6V DC
• Output Signal: Digital signal via a single-bus
• Measuring Range:
  • Humidity: 0-100% RH
  • Temperature: -40°C to 80°C (-40°F to 176°F)
• Accuracy:
  • Humidity: ±2% RH
  • Temperature: ±0.5°C
• Resolution:
  • Humidity: 0.1% RH
  • Temperature: 0.1°C
• Sampling Rate: ≤ 2 seconds

1. Power Supply: Connect the VCC pin to a 3.3V or 5V supply from your microcontroller board.
2. Data Signal: Connect the DATA pin to a digital I/O pin on your microcontroller.
3. Ground: Connect the GND pin to the ground on your microcontroller board.
4. Pull-up Resistor: A 5.1kΩ to 10kΩ pull-up resistor is typically required between the VCC and DATA pins.

• Avoid placing the sensor in direct sunlight or near heat sources for accurate readings.
• Ensure the sensor is not exposed to condensing humidity levels.
• Allow the sensor to acclimate to the environment for accurate readings.
• Use shielded/filtered cables if the sensor is placed in an environment with high electromagnetic interference.

#include "DHT.h"

#define DHTPIN 2     // Digital pin connected to the DHT sensor
#define DHTTYPE DHT22   // DHT 22 (AM2302)

DHT dht(DHTPIN, DHTTYPE);

void setup() {
  Serial.begin(9600);
  dht.begin();
}

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

  // Reading temperature or humidity takes about 250 milliseconds!
  float humidity = dht.readHumidity();
  // Read temperature as Celsius (the default)
  float temperature = dht.readTemperature();

  // Check if any reads failed and exit early (to try again).
  if (isnan(humidity) || isnan(temperature)) {
    Serial.println(F("Failed to read from DHT sensor!"));
    return;
  }

  // Compute heat index in Celsius (isFahrenheit = false)
  float heatIndex = dht.computeHeatIndex(temperature, humidity, false);

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

• Inaccurate Readings: Ensure the sensor is not placed near heat sources or in direct sunlight.
• No Data: Check the wiring, especially the pull-up resistor on the data line.
• Erratic Readings: Ensure there's no condensation on the sensor and it's acclimated to the environment.

• Sensor Not Responding: Verify the power supply and connections. Reset the microcontroller and try reading again.
• Consistently High Humidity Readings: Check for any moisture or condensation on the sensor and dry it gently if necessary.
• Long Cable Runs: Use shielded cables and keep the cable length as short as possible to minimize signal degradation.

Q: Can the sensor be used outdoors? A: Yes, but it should be protected from direct sunlight, rain, and condensation.

Q: How long does the sensor need to acclimate to a new environment? A: It typically takes about 30 minutes to an hour for the sensor to stabilize and provide accurate readings.

Q: Is calibration required for the sensor? A: The DHT22 sensor comes pre-calibrated from the factory. However, for critical applications, periodic calibration against a known standard may be necessary.