DHT22 + ESP32: Pinout, Wiring Diagram and Working Code

What is the DHT22 module pinout?

Compoden's DHT22 ships soldered to a small carrier board with a 3-pin header. The listing photo shows + and − printed at the two ends of the header; the middle pin is the data line. The bare AM2302 sensor on top has four legs (power, data, ground and one unused), which the carrier reduces to three.

DHT22 carrier board pins (from the listing photo and description)

Pin	Function	Source
+	Supply, 3.3–5.5 V	Photo silkscreen + AM2302 manual
Middle (OUT / DATA)	Single-wire bidirectional data; the carrier has an on-board pull-up	Listing (label not legible in photo)
−	Ground	Photo silkscreen

Check the middle pin's label on your board before powering it. If you have a bare four-leg DHT22 instead, follow the pin numbering in the Aosong AM2302 manual and add a pull-up resistor on the data line (the manual suggests 5.1 kΩ).

How do you wire the DHT22 to an ESP32?

DHT22 module to ESP32 DevKit (30-pin) wiring

DHT22 pin	ESP32 DevKit pin	Why this pin
+	3V3	Keeps the pull-up, and so the data line, at 3.3 V
OUT / DATA	GPIO4	Ordinary bidirectional GPIO; not a strapping, flash or serial pin
−	GND	Common ground

Which ESP32 pins should you avoid?

Every GPIO choice on this page follows the same rules for the 30-pin ESP32-WROOM-32 DevKit (the board Compoden stocks as the ESP32 30-pin CP2102 development board). Espressif's ESP32 GPIO reference is the source:

• Never use GPIO6–11. They connect to the module's SPI flash.
• Avoid the strapping pins GPIO0, 2, 5, 12 and 15 for sensors. Their level at reset decides boot mode and flash voltage, so a sensor holding one of them can stop the board booting. GPIO0 is not even on the 30-pin header; it only goes to the BOOT button.
• GPIO34, 35, 36 and 39 are input-only and have no internal pull-up or pull-down. They are ideal for analog inputs and useless for outputs or clocks.
• Use ADC1 (GPIO32–39) for analog readings. ADC2 pins (GPIO0, 2, 4, 12–15, 25–27) cannot be read while Wi-Fi is running.
• Leave GPIO1 and GPIO3 alone. They carry the USB serial link used for uploads and the Serial Monitor.
• ESP32 GPIOs are 3.3 V only. They are not 5 V tolerant.

Should the DHT22 run on 3.3 V or 5 V with an ESP32?

The Aosong AM2302 manual allows 3.3–5.5 V and suggests 5 V. With an ESP32, use 3.3 V anyway. The listing states the carrier has a 4.7 kΩ pull-up from the data line to the supply, so a 5 V supply would put 5 V on an ESP32 GPIO that is not 5 V tolerant.

The manual's trade-off for 3.3 V operation: keep the wire to the sensor under 1 metre, or the voltage drop starves the sensor and readings drift. If you need a long cable, power the sensor at 5 V and use a proper level shifter on the data line.

Working Arduino code for the DHT22 on ESP32

Install DHT sensor library from the Library Manager and accept the dependency it asks for. The sketch waits 2 seconds after power-up, then reads every 2.5 seconds, following the manual's timing rules.

// DHT22 (AM2302) module + ESP32 DevKit (ESP32-WROOM-32)
// Wiring: + -> 3V3, OUT (middle) -> GPIO4, - -> GND. Keep the cable under 1 m at 3.3 V.
// Library: "DHT sensor library" (Library Manager; accept its dependency)
#include <DHT.h>

const int DHT_PIN = 4;
DHT dht(DHT_PIN, DHT22);

void setup() {
  Serial.begin(115200);
  dht.begin();
  delay(2000);                      // datasheet: wait more than 2 s after power-up
}

void loop() {
  float humidity = dht.readHumidity();
  float tempC = dht.readTemperature();
  if (isnan(humidity) || isnan(tempC)) {
    Serial.println("DHT22 read failed. Check DATA on GPIO4, 3V3 and GND.");
  } else {
    Serial.printf("Temperature: %.1f C  Humidity: %.1f %%\n", tempC, humidity);
  }
  delay(2500);                      // datasheet: no faster than one read every 2 s
}

Compile check: this exact sketch compiled for the esp32:esp32:esp32 board (ESP32 Dev Module, ESP32 Arduino core 3.3.10) on 5 October 2026. A clean compile proves the code and libraries agree. It does not prove your wiring, so test it on the bench with the Serial Monitor at 115200 baud.

The manual notes that each reading returns the result of the previous measurement. If you read only once after a long sleep, take two readings and keep the second.

Common mistakes with the DHT22 and ESP32

• Powering the module from 5 V into an ESP32. The on-board pull-up then drives the data pin to 5 V.
• Reading faster than every 2 seconds. The manual warns this gives wrong values or failed reads.
• Declaring DHT11 in the code. The two sensors use different data formats; use DHT22.
• Using a strapping pin such as GPIO2, 5, 12 or 15. The pull-up can change the boot mode. GPIO4 avoids this.
• Long cable at 3.3 V. Over about 1 m the manual expects measurement errors.
• Expecting it to survive rain. The listing notes the bare module is not weatherproof.

Where can you get the parts?

Parts used in this guide (Compoden catalogue)

Item	Role	Link
DHT22 temperature and humidity module	Temperature and humidity sensor	View DHT22 module
ESP32 30-pin CP2102 development board	Controller with Wi-Fi and Bluetooth	View ESP32 board

Want this sensor in a bigger build? Describe the whole device in Soldr, for example “I want to build a room temperature and humidity monitor with an ESP32 and a DHT22”. Soldr returns the exact parts, a wiring map and code that compiles, all from one parts list, so the pins in the code match the pins in the wiring. Compoden stocks the parts and delivers across India.

Sources

Supply range, pull-up, cable-length and timing rules: Aosong AM2302 technical manual. ESP32 pin rules: Espressif ESP32 GPIO reference. Carrier pull-up and pin names: the Compoden listing and its photo.

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Frequently asked questions

Which ESP32 pin should I use for the DHT22?

Any ordinary GPIO that is not a strapping, flash or serial pin. GPIO4 is a safe choice on the 30-pin ESP32 DevKit. Power the module from 3V3 and connect its − pin to GND.

Can I power the DHT22 from 5 V with an ESP32?

Not with the carrier board wired straight to a GPIO, because its pull-up would put 5 V on the data line. Use 3.3 V with a cable under 1 m, or 5 V with a level shifter.

Why does my DHT22 return NaN on the ESP32?

Usually the read interval is under 2 seconds, the code declares DHT11, the data wire is on the wrong GPIO or the cable is too long for 3.3 V. Check those four before suspecting the sensor.