libraries: switch to dht11.h from keyestudio

a93d1575a96c77b5cc9184bf3ceca3ecf9d61779  /home/vbatts/KS0530 Keyestudio Solar Tracking Kit.zip
fea14b18807e3dac4b112354eefb76a5e0f76c4b  /home/vbatts/KS0530 Keyestudio Solar Tracking Kit/Libraries/Dht11.zip

Dht11/examples/dht11/dht11.ino

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+double Fahrenheit(double celsius) 
+{
+        return 1.8 * celsius + 32;
+}    //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 * (A0-1);
+        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/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);
+}