DH11数字温湿度传感器

DH11数字温湿度传感器是一种集温度、湿度一体的复合传感器，它能把温度和湿度物理量通过温、湿度敏感元件和相应电路转化成方便计算机、PLC、智能仪表等数据采集设备直接读取的数字量。DHT11由电阻式感湿器件和NTC系数感温器件构成，具有校准数字信号输出功能，采用单总线串行接口，输出数据一共5个字节，分别表示：湿度整数位、湿度小数位，温度整数位、温度小数位及校验和，其中检验和为湿度与温度之和的最低八位数据。

arduino引脚	模块引脚
D2	S
5V	VCC
GND	GND

 double Fahrenheit(double celsius)
 {
         return 1.8 * celsius + ;
 }    //摄氏温度度转化为华氏温度

 double Kelvin(double celsius)
 {
         return celsius + 273.15;
 }     //摄氏温度转化为开氏温度

 // 露点（点在此温度时，空气饱和并产生露珠）
 // 参考: 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-);
         SUM += 5.02808 * log10(A0);
         SUM += -1.3816e-7 * (pow(, (11.344*(-/A0)))-) ;
         SUM += 8.1328e-3 * (pow(,(-3.49149*(A0-)))-) ;
         SUM += log10(1013.246);
         double VP = pow(, SUM-) * humidity;
         double T = log(VP/0.61078);   // temp var
         return (241.88 * T) / (17.558-T);
 }

 // 快速计算露点，速度是5倍dewPoint()
 // 参考: 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/);
         double Td = (b * temp) / (a - temp);
         return Td;
 }

 #include <dht11.h>

 dht11 DHT11;

 #define DHT11PIN 2

 void setup()
 {
   Serial.begin();
   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, );

   Serial.print("Temperature (oC): ");
   Serial.println((float)DHT11.temperature, );

   Serial.print("Temperature (oF): ");
   Serial.println(Fahrenheit(DHT11.temperature), );

   Serial.print("Temperature (K): ");
   Serial.println(Kelvin(DHT11.temperature), );

   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();
 }