GK-AS-DHT11 geeekus Digital Temperature Humidity Moisture DHT11 Sensor Breakout Board Module

The geeekus DHT11 temperature and humidity sensor is a low-cost and easy-to-use device for measuring ambient temperature and humidity levels by connecting it to a microcontroller.

It uses a capacitive humidity sensing element and a thermistor to measure the relative humidity and temperature, respectively. The sensor outputs a 16-bit digital signal over a single-wire interface, making it simple to use with microcontrollers such as an Arduino. The DHT11 is commonly used in a wide range of applications, including home automation systems, weather stations, and HVAC control systems. 

The DHT11 detects water vapor by measuring the electrical resistance between two electrodes. The humidity sensing component is a moisture holding substrate with electrodes applied to the surface. When water vapor is absorbed by the substrate, ions are released by the substrate which increases the conductivity between the electrodes. The change in resistance between the two electrodes is proportional to the relative humidity. Higher relative humidity decreases the resistance between the electrodes, while lower relative humidity increases the resistance between the electrodes.

The DHT11 measures temperature with a surface mounted NTC temperature sensor (thermistor) built into the unit.

An IC mounted on the back of the unit converts the resistance measurement to relative humidity. It also stores the calibration coefficients, and controls the data signal transmission between the DHT11 and the Arduino

The DHT11 uses just one signal wire to transmit data to the Arduino. Power comes from separate 5V and ground wires. A 10K Ohm pull-up resistor is needed between the signal line and 5V line to make sure the signal level stays high by default

Aosong DHT11 is factory-calibrated and communicates with a microcontroller over only 1 digital I/O pin

Specifications

• Supply Voltage: +5 V
• Temperature Range: 0-50 °C error of ± 2 °C
• Humidity: 20-90% RH ± 5% RH error
• Interface: Digital

Arduino Library and Example for DHTxx Sensors

Sample Code:

#include <dht11.h>
dht11 DHT;
#define DHT11_PIN 4
  
void setup(){
  Serial.begin(9600);
  Serial.println("DHT TEST PROGRAM ");
  Serial.print("LIBRARY VERSION: ");
  Serial.println(DHT11LIB_VERSION);
  Serial.println();
  Serial.println("Type,\tstatus,\tHumidity (%),\tTemperature (C)");
}
  
void loop(){
  int chk;
  Serial.print("DHT11, \t");
  chk = DHT.read(DHT11_PIN);    // READ DATA
  switch (chk){
    case DHTLIB_OK:  
                Serial.print("OK,\t"); 
                break;

case DHTLIB_ERROR_CHECKSUM: 

                Serial.print("Checksum error,\t"); 
                break;
    case DHTLIB_ERROR_TIMEOUT: 
                Serial.print("Time out error,\t"); 
                break;
    default: 
                Serial.print("Unknown error,\t"); 
                break;
  }
 // DISPLAT DATA
  Serial.print(DHT.humidity,1);
  Serial.print(",\t");
  Serial.println(DHT.temperature,1);
  
  delay(1000);
}