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DHT11 Temperature / Humidity Sensor

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AOSONG
RRP: $1.95
$1.50
(You save $0.45)
SKU:
CIC-0000011
Weight:
0.10 Ounces
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 Product Description

DHT11 Temperature and Humidity Sensor

Specifications

  • Temperature Sensor IC
  • Relative humidity Resolution: 16Bit, Repeatability: ±1% RH, Accuracy: At 25°C ±5% RH
  • Temperature Resolution: 16Bit, Repeatability: ±0.2°C, Range: At 25°C ±2°C Response time: 1 / e (63%) 10S
  • Electrical Characteristics, Power supply: DC 3.5~5.5V, Current: measurement 0.3mA standby 60µ A
  • Sampling period: more than 2 seconds
Pin Description
  1. VDD power supply 3.5~5.5V DC 
  2. DATA serial data, a single bus
  3. NC, empty pin
  4. GND ground

 Product Documents

Datasheet


#include 



//

// PURPOSE: DHT11 library test sketch for Arduino

//



//Celsius to Fahrenheit conversion

double Fahrenheit(double celsius)

{

        return 1.8 * celsius + 32;

}



//Celsius to Kelvin conversion

double Kelvin(double celsius)

{

        return celsius + 273.15;

}



// dewPoint function NOAA

// reference: http://wahiduddin.net/calc/density_algorithms.htm

double dewPoint(double celsius, double humidity)

{

        double A0= 373.15/(273.15 + celsius);

        double SUM = -7.90298 * (A0-1);

        SUM += 5.02808 * log10(A0);

        SUM += -1.3816e-7 * (pow(10, (11.344*(1-1/A0)))-1) ;

        SUM += 8.1328e-3 * (pow(10,(-3.49149*(A0-1)))-1) ;

        SUM += log10(1013.246);

        double VP = pow(10, SUM-3) * humidity;

        double T = log(VP/0.61078);   // temp var

        return (241.88 * T) / (17.558-T);

}



// delta max = 0.6544 wrt dewPoint()

// 5x faster than dewPoint()

// reference: http://en.wikipedia.org/wiki/Dew_point

double dewPointFast(double celsius, double humidity)

{

        double a = 17.271;

        double b = 237.7;

        double temp = (a * celsius) / (b + celsius) + log(humidity/100);

        double Td = (b * temp) / (a - temp);

        return Td;

}



dht11 DHT11;



#define DHT11PIN 2



void setup()

{

  Serial.begin(115200);

  Serial.println("DHT11 TEST PROGRAM ");

  Serial.print("LIBRARY VERSION: ");

  Serial.println(DHT11LIB_VERSION);

  Serial.println();

}



void loop()

{

  Serial.println("\n");



  int chk = DHT11.read(DHT11PIN);



  Serial.print("Read sensor: ");

  switch (chk)

  {

    case DHTLIB_OK:

                Serial.println("OK");

                break;

    case DHTLIB_ERROR_CHECKSUM:

                Serial.println("Checksum error");

                break;

    case DHTLIB_ERROR_TIMEOUT:

                Serial.println("Time out error");

                break;

    default:

                Serial.println("Unknown error");

                break;

  }



  Serial.print("Humidity (%): ");

  Serial.println((float)DHT11.humidity, 2);



  Serial.print("Temperature (oC): ");

  Serial.println((float)DHT11.temperature, 2);



  Serial.print("Temperature (oF): ");

  Serial.println(Fahrenheit(DHT11.temperature), 2);



  Serial.print("Temperature (K): ");

  Serial.println(Kelvin(DHT11.temperature), 2);



  Serial.print("Dew Point (oC): ");

  Serial.println(dewPoint(DHT11.temperature, DHT11.humidity));



  Serial.print("Dew PointFast (oC): ");

  Serial.println(dewPointFast(DHT11.temperature, DHT11.humidity));



  delay(2000);

}

//

// END OF FILE

//

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