Interfacing DHT11 Humidity & Temperature Sensor with Arduino

Welcome to this beginner-friendly Arduino tutorial on the dht11. By the end of the guide, you'll wire the module to an Arduino UNO, flash a short sketch, and read live values on the Serial Monitor — no prior electronics experience required.

What you'll learn

• How the module works in plain language
• The exact parts you need and how to wire them safely
• The full Arduino IDE sketch with comments
• Common issues and how to fix them

Arduino code

Open the Arduino IDE, paste the sketch below into a new file, install any libraries the sketch #includes (Tools → Manage Libraries), select your board and COM port, then click Upload.

#include <Adafruit_Sensor.h>
#include <DHT.h>
#include <DHT_U.h>
#define DHTTYPE    DHT11     // DHT 11
#define DHTPIN 2
DHT_Unified dht(DHTPIN, DHTTYPE);
uint32_t delayMS;
void setup() {
  Serial.begin(9600);
  dht.begin();
  sensor_t sensor;
  delayMS = sensor.min_delay / 1000;
}

void loop()
{
  sensors_event_t event;
  dht.temperature().getEvent(&event);
  Serial.print(F("Temperature: "));
  Serial.print(event.temperature);
  Serial.println(F("°C"));
  dht.humidity().getEvent(&event);
  Serial.print(F("Humidity: "));
  Serial.print(event.relative_humidity);
  Serial.println(F("%"));
  delay(delayMS);
}

How it works

The sketch initialises serial communication and the dht11 driver in setup(), then in loop() it samples the sensor at a regular interval and prints the result to the Serial Monitor at 9600 baud. Open the Serial Monitor (Ctrl+Shift+M) after upload to see live readings.

Troubleshooting checklist

• No readings: verify the baud rate in Serial Monitor matches the sketch (usually 9600).
• Garbage characters: wrong baud rate or loose GND wire.
• Library not found: install the exact library referenced in the #include line via Library Manager.
• Sensor not detected (I²C): run an I²C scanner sketch to confirm the address.

What to build next

Once the basic readout works, try logging values to an SD card, sending them over Wi-Fi with an ESP32, or pushing them to a Blynk IoT dashboard. Pair this module with our simulator round-up to prototype the circuit before soldering.