DHT22 / AM2302 with ESP32: Wiring & Arduino Readings

Read room temperature and relative humidity from the DHT22 / AM2302 module using an ESP32. This is a digital single-data-line sensor; it does not appear in an I2C address scanner.

Identify the module and signal pin

The linked product includes PCB and D1-mini-style options. Read the actual VCC, DATA and GND markings before connecting it. A bare four-pin sensor and a three-pin breakout do not share a universal left-to-right connector order. Select DHT22 in the code for an AM2302/DHT22 device, not DHT11.

Prepare the ESP32

Use a working ESP32-C3 Supermini, a USB data cable and short jumper wires. The example selects GPIO4 as the data pin and uses 3.3 V supply and logic. For a different board, choose a free exposed GPIO and update DATA_PIN. Keep the sensor away from the USB regulator and the ESP32 package when checking room-air readings.

Wire power, data and the pull-up

Inspect whether the breakout already includes a data pull-up before adding another. If it is a plug-on D1 mini shield, confirm its signal route first; do not plug that footprint onto an unrelated ESP32 header. On an ESP8266 D1 mini, the printed D labels differ from GPIO numbers.

Install the DHT library

In Arduino Library Manager install DHT sensor library by Adafruit and Adafruit Unified Sensor. Accept the listed dependencies. Create a new sketch, paste the complete example, click Verify, then Upload. Keep a record of your board profile and library versions when reporting an issue.

Keep the DHT22 type selected even if the enclosure is marked AM2302. A library for an AHT20, SHT4x or another I2C humidity sensor uses a different protocol and will not read this sensor.

Upload a temperature and humidity test

The loop waits 2.5 seconds between readings. Do not remove this delay to make the display update faster: the DHT22 has a slow measurement cycle. Failed reads are checked before numbers are printed.

#include <Arduino.h>
#include <DHT.h>

constexpr int DATA_PIN = 4; // GPIO4, not a D1-mini D-number.
DHT climate(DATA_PIN, DHT22);
void setup() {
  Serial.begin(115200);
  climate.begin();
}
void loop() {
  delay(2500);
  const float humidity = climate.readHumidity();
  const float celsius = climate.readTemperature();
  if (isnan(humidity) || isnan(celsius)) {
    Serial.println("DHT read failed; check sensor type, pull-up and wiring.");
  } else {
    Serial.printf("Temperature: %.1f C | Humidity: %.1f %%RH\n", celsius, humidity);
  }
}

Check readings and placement

1. Open Serial Monitor at 115200 baud and wait for several successful samples.
2. Let the sensor settle after handling before comparing it with a reference.
3. Record both instruments in the same place and out of direct sunlight.
4. If readings are consistently warm, move the sensor away from the controller and enclosure heat.

This example reads Celsius and percent relative humidity. Short-term variations do not establish a calibration error. If you need an I2C sensor for a larger bus, continue with the separate AHT20 guide rather than trying to change the DHT communication protocol.

Troubleshooting

References and further reading

• Adafruit DHT Arduino tutorial
• DHT sensor library
• ESP32-C3 Supermini setup

Related product

DHT22 AM2302 Digital Temperature and Humidity Sensor AM2302 Module + PCB For D1 Mini development board or Arduino →