DH11數字溫濕度傳感器

DH11數字溫濕度傳感器是一種集溫度、濕度一體的復合傳感器，它能把溫度和濕度物理量通過溫、濕度敏感元件和相應電路轉化成方便計算機、PLC、智能儀表等數據采集設備直接讀取的數字量。DHT11由電阻式感濕器件和NTC系數感溫器件構成，具有校准數字信號輸出功能，采用單總線串行接口，輸出數據一共5個字節，分別表示：濕度整數位、濕度小數位，溫度整數位、溫度小數位及校驗和，其中檢驗和為濕度與溫度之和的最低八位數據。

arduino引腳	模塊引腳
D2	S
5V	VCC
GND	GND

double Fahrenheit(double celsius) 
{
        return 1.8 * celsius + 32;
}    //攝氏溫度度轉化為華氏溫度

double Kelvin(double celsius)
{
        return celsius + 273.15;
}     //攝氏溫度轉化為開氏溫度

// 露點（點在此溫度時，空氣飽和並產生露珠）
// 參考: 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);
}

// 快速計算露點，速度是5倍dewPoint()
// 參考: 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;
}

#include <dht11.h>

dht11 DHT11;

#define DHT11PIN 2

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