Sensor de Umidade e Temperatura DHT11 - Arquivo 007

Referência:
Exemplo da biblioteca hdt11.h

Lista de Materiais:
IDE Arduino 1.0.6
1x  Board Arduino UNO
1x  Protoboard 830 furos
1x  Cabo USB-A male to USB-B male 
1x  Conj. de fios jumper p/ protoboard
1x  Sensor de umidade HDT11

Montagem:

Firmware:
#include <dht11.h>

dht11 DHT11;

#define DHT11PIN 2

void setup(){
  Serial.begin(9600);
}

void loop(){
  int chk = DHT11.read(DHT11PIN);

  Serial.print("Read sensor: ");
  switch (chk){
    case 0: Serial.println("OK"); break;
    case -1: Serial.println("Checksum error"); break;
    case -2: 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));
  
  Serial.println("\n");

  delay(2000);
}
//*******************************************************************************

double Fahrenheit(double celsius){

  return 1.8 * celsius + 32;
}
//*******************************************************************************

double Kelvin(double celsius){

  return celsius + 273.15;
}
//*******************************************************************************

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

Download: dht11.h