DHT12 Temperature and Humidity Sensor

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These sensors are cheap and widely available. To use them with an Arduino use the sketch / libraries below.


Beware many sellers say the DHT12 compatible with the DHT11 this is NOT correct, they look the same but the wiring and protocols are DIFFERENT and you need new libraries for the DHT12

http://playground.arduino.cc/Main/Dht

While these are not as accurate as the DHT22 they can be calibrated individually (just add an offset Vs a know good Temp ref. The humidity sensing might be ok depending on your needs.

If you need accuracy go for the DHT22 but these are great for low cost, low resolution applications. Worth getting a few and calibrating Vs DHT22 and the note the offsets in the temperature ranges you care about.


/*  
 *   Example for a DHT12 sensor
 *   Beware some of the diagrams about the pinouts are incorrect.
 *   Pin Definition 1.VDD 2.SDA 3.GND 4.SCL
 *   Look at the sensor one side has holes to allow air inside. Lets call the surface with holes the FRONT
 *   The BACK of the sensor has printed codes and no holes
 *   The 4 PINS for connection come out of the BOTTOM of the sensor
 *   OK so we have defined the orientation of the sensor. 
 *   Looking at the FRONT of the Sensor with the legs pointing down the LEFTMOST PIN is PIN ONE
 *   
 *   -----------------
 *   !   O O O O O   !
 *   !   O O O O O   !
 *   !   O O O O O   !
 *   !   O O O O O   !
 *   -----------------
 *       !  !  !  !
 *       !  !  !  !
 *       !  !  !  !
 *       !  !  !  ! 
 *       1  2  3  4
 *       
*/

 #include
#include

dht12 DHT(0x5c);

 void setup()
{
  Serial.begin(9600);
  Serial.println(F("DHT12 TEST PROGRAM"));
}

 void loop()
{
  unsigned long b = micros();
  dht::ReadStatus chk = DHT.read();
  unsigned long e = micros();

   Serial.print(F("Read sensor: "));
  switch (chk)
  {
    case dht::OK:
      Serial.print(F("OK, took "));
      Serial.print (e - b); Serial.print(F(" usec, "));
      break;
    case dht::ERROR_CHECKSUM:
      Serial.println(F("Checksum error"));
      break;
    case dht::ERROR_TIMEOUT:
      Serial.println(F("Timeout error"));
      break;
    case dht::ERROR_CONNECT:
      Serial.println(F("Connect error"));
      break;
    case dht::ERROR_ACK_L:
      Serial.println(F("AckL error"));
      break;
    case dht::ERROR_ACK_H:
      Serial.println(F("AckH error"));
      break;
    default:
      Serial.println(F("Unknown error"));
      break;
  }

   Serial.print(F("Humidity: "));
  Serial.print((float)DHT.getHumidity()/(float)10);
  Serial.print(F("%, "));

   Serial.print(F(". Temperature (degrees C): "));
  Serial.print((float)DHT.getTemperature()/(float)10);

   Serial.print(F(", Dew Point (degrees C): "));
  Serial.println(DHT.dewPoint());

   delay(4000);
}
//
// END OF FILE
//