Added Convenience Methods

.gitignore

@@ -0,0 +1,31 @@
+# Vi files
+*~
+
+# Compiled Object files
+*.slo
+*.lo
+*.o
+*.obj
+
+# Precompiled Headers
+*.gch
+*.pch
+
+# Compiled Dynamic libraries
+*.so
+*.dylib
+*.dll
+
+# Fortran module files
+*.mod
+
+# Compiled Static libraries
+*.lai
+*.la
+*.a
+*.lib
+
+# Executables
+*.exe
+*.out
+*.app

DHT.cpp

@@ -8,7 +8,16 @@ written by Adafruit Industries
 
 #define MIN_INTERVAL 2000
 
-DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
+// Old constructor.
+//DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
+
+/*
+ * New constructor.
+ *
+ * Note that count is now ignored as the DHT reading algorithm adjusts itself
+ * based on the speed of the processor.
+ */
+DHT::DHT(uint8_t pin, uint8_t type) {
   _pin = pin;
   _type = type;
   #ifdef __AVR
@@ -17,10 +26,9 @@ DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
   #endif
   _maxcycles = microsecondsToClockCycles(1000);  // 1 millisecond timeout for
                                                  // reading pulses from DHT sensor.
-  // Note that count is now ignored as the DHT reading algorithm adjusts itself
-  // basd on the speed of the processor.
 }
 
+
 void DHT::begin(void) {
   // set up the pins!
   pinMode(_pin, INPUT_PULLUP);
@@ -152,8 +160,12 @@ boolean DHT::read(bool force) {
     InterruptLock lock;
 
     // End the start signal by setting data line high for 40 microseconds.
-    digitalWrite(_pin, HIGH);
-    delayMicroseconds(40);
+    //digitalWrite(_pin, HIGH);
+    //delayMicroseconds(40);
+    // WEB: This is an error. DHT tries to pull the line low as soon as it came back to high.
+    // therefore the low-high transition after the start signal "low" needs to be realised by
+    // the pullup resistor only, uC pin must already be in INPUT mode.
+    // ref: https://github.com/adafruit/DHT-sensor-library/issues/48
 
     // Now start reading the data line to get the value from the DHT sensor.
     pinMode(_pin, INPUT_PULLUP);

DHT.h

@@ -37,11 +37,28 @@ written by Adafruit Industries
 
 class DHT {
   public:
-   DHT(uint8_t pin, uint8_t type, uint8_t count=6);
+   // Note that count is now ignored as the DHT reading algorithm adjusts itself
+   // based on the speed of the processor.
+   DHT(uint8_t pin, uint8_t type, uint8_t count) {
+     DHT(pin, type);
+   };
+   DHT(uint8_t pin, uint8_t type);
    void begin(void);
+   float readFahrenheit(bool force=false) {
+       return readTemperature(true, force);
+   };
+   float readCelcius(bool force=false) {
+       return readTemperature(false, force);
+   };
    float readTemperature(bool S=false, bool force=false);
    float convertCtoF(float);
    float convertFtoC(float);
+   float computeHeatIndexFahrenheit(float temperature, float percentHumidity) {
+       return computeHeatIndex(temperature, percentHumidity, true);
+   };
+   float computeHeatIndexCelcius(float temperature, float percentHumidity) {
+       return computeHeatIndex(temperature, percentHumidity, false);
+   };
    float computeHeatIndex(float temperature, float percentHumidity, bool isFahrenheit=true);
    float readHumidity(bool force=false);
    boolean read(bool force=false);
@@ -59,6 +76,7 @@ class DHT {
 
   uint32_t expectPulse(bool level);
 
+  void _init(uint8_t pin, uint8_t type);
 };
 
 class InterruptLock {