FREE SIMULATOR EXAMPLE · BEGINNER

Pico: DHT22 Temperature & Humidity

This example reads temperature and humidity from a DHT22 sensor wired to GPIO7 of the Raspberry Pi Pico, printing both values to the Serial Monitor every two seconds. It uses the same Adafruit DHT library you would install on real hardware, so the code transfers directly to a physical build.

Board	Raspberry Pi Pico (RP2040 dual-core Cortex-M0+, 133 MHz)
Difficulty	beginner
Category	sensors
Libraries	DHT sensor library
Runs in	Sensbench browser simulator — free, no account

The exact circuit you get when you open this example — already wired, ready to run.

The sketch

// Raspberry Pi Pico — DHT22 Temperature & Humidity
// Requires: Adafruit DHT sensor library (install via Library Manager)
// Wiring: DATA → GP7  |  VCC → 3.3V  |  GND → GND

#include <DHT.h>

#define DHT_PIN  7   // GPIO 7
#define DHT_TYPE DHT22

DHT dht(DHT_PIN, DHT_TYPE);

void setup() {
  Serial.begin(115200);
  dht.begin();
  delay(1000);
  Serial.println("Pico DHT22 ready!");
}

void loop() {
  delay(2000);
  float h = dht.readHumidity();
  float t = dht.readTemperature();
  if (isnan(h) || isnan(t)) {
    Serial.println("DHT22 read error!");
    return;
  }
  Serial.print("Temp: "); Serial.print(t, 1); Serial.print(" C   ");
  Serial.print("Humidity: "); Serial.print(h, 1); Serial.println(" %");
}

How it works

The DHT22 talks a single-wire protocol on the data line: strict timing, 40 bits per reading. You never see any of that — the DHT object from the Adafruit library handles the bit-banging. dht.begin() in setup() initializes it, then dht.readTemperature() and dht.readHumidity() in the loop return the two values.

Wiring is three wires: DATA to GP7, VCC to 3V3, GND to GND. The 1-second delay after dht.begin() gives the sensor time to power up — the DHT22 is famously unresponsive in the first second after power-on, and a read in that window returns garbage.

Before you build it for real

Get the parts

Related examples

FAQ

Why does the code wait 2 seconds between reads?

The DHT22 is a slow sensor by design: it needs about 1.5-2 seconds between readings to sample its internal thermistor and humidity capacitor. The delay(2000) at the top of the loop is not politeness — polling faster returns stale or NaN values, and some DHT22 clones will hang the data line entirely if you hammer them.

Why is there an isnan() check?

DHT sensors fail checksums regularly — it is normal, not a bug. The library returns NaN when a read is bad, and the sketch prints a clean error instead of garbage numbers. On real hardware, frequent NaNs are usually a wiring problem (missing pull-up, wrong pin, power sag).