How to Use DHT11: Examples, Pinouts, and Specs

The DHT11 is a basic, low-cost digital temperature and humidity sensor. 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
• Data logging

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).

• Pull-up Resistor: Use a 10kΩ pull-up resistor between the Data pin and VCC to ensure reliable communication.
• Sampling Rate: Do not sample the sensor more than once per second to avoid inaccurate readings.
• Placement: Place the sensor in a location where it can accurately measure the ambient temperature and humidity without interference.

  +-------------------+
  |                   |
  |    DHT11 Sensor   |
  |                   |
  +-------------------+
       |   |   |   |
       |   |   |   |
      VCC Data NC GND
       |   |       |
       |   |       |
      5V  D2      GND
       |   |       |
       |   |       |
      +---+-------+
          |
         10kΩ
          |
         VCC

#include "DHT.h"

#define DHTPIN 2     // Pin connected to the Data pin of DHT11
#define DHTTYPE DHT11   // Define the type of DHT sensor

DHT dht(DHTPIN, DHTTYPE);

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

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

  float humidity = dht.readHumidity();
  float temperature = dht.readTemperature();

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

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

1. No Data Output: Ensure the sensor is properly connected and the pull-up resistor is in place.
2. Inaccurate Readings: Check the sampling rate and ensure it is not faster than once per second.
3. Sensor Not Responding: Verify the power supply voltage and connections.

• Check Connections: Double-check all connections, especially the Data pin and pull-up resistor.
• Power Supply: Ensure the sensor is receiving the correct voltage (3.3V to 5.5V).
• Library Compatibility: Make sure you are using a compatible library for the DHT11 sensor.

By following this documentation, users should be able to effectively integrate and troubleshoot the DHT11 temperature and humidity sensor in their projects.