How to Use DHT11: Examples, Pinouts, and Specs

The DHT11 is a basic, low-cost digital temperature and humidity sensor manufactured by Arduino. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and outputs a digital signal on the data pin. This sensor is widely used in various applications due to its simplicity and affordability.

• Home automation systems
• Weather stations
• Environmental monitoring
• HVAC systems
• Greenhouse monitoring

1. Power Supply: Connect the VCC pin to a 3.3V or 5V power supply.
2. Ground: Connect the GND pin to the ground of the circuit.
3. Data Pin: Connect the Data pin to a digital input pin on your microcontroller (e.g., Arduino UNO).

• Pull-up Resistor: Use a 10kΩ pull-up resistor between the Data pin and VCC to ensure reliable communication.
• Sampling Rate: The DHT11 has a sampling rate of 1Hz, meaning it can provide one reading per second. Avoid querying the sensor more frequently to prevent inaccurate readings.
• Wiring Length: Keep the wiring between the sensor and the microcontroller as short as possible to minimize signal degradation.

#include "DHT.h"

#define DHTPIN 2     // Pin where the DHT11 is connected
#define DHTTYPE DHT11   // DHT 11

DHT dht(DHTPIN, DHTTYPE);

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

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

  float h = dht.readHumidity();
  float t = dht.readTemperature();

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

  Serial.print("Humidity: ");
  Serial.print(h);
  Serial.print(" %\t");
  Serial.print("Temperature: ");
  Serial.print(t);
  Serial.println(" *C");
}

1. No Data Output: Ensure the Data pin is connected correctly and the pull-up resistor is in place.
2. Inaccurate Readings: Check the power supply voltage and ensure it is within the specified range. Also, verify the sampling rate is not too high.
3. Sensor Not Responding: Ensure the sensor is not damaged and is connected to the correct pins on the microcontroller.

• Check Connections: Verify all connections are secure and correct.
• Use a Pull-up Resistor: Ensure a 10kΩ pull-up resistor is used between the Data pin and VCC.
• Power Supply: Ensure the sensor is powered with a stable voltage within the specified range.
• Code Verification: Double-check the code for any errors and ensure the correct library is included.

By following this documentation, users can effectively integrate the DHT11 sensor into their projects, ensuring accurate temperature and humidity measurements.