Merge branch 'master' of https://github.com/adafruit/DHT-sensor-library

As correctly stated by Mausy5043, the division is quite slow in most
microcontrollers, so I have replaced them with multiplications.

DHT.cpp

@@ -11,8 +11,10 @@ written by Adafruit Industries
 DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
   _pin = pin;
   _type = type;
-  _bit = digitalPinToBitMask(pin);
-  _port = digitalPinToPort(pin);
+  #ifdef __AVR
+    _bit = digitalPinToBitMask(pin);
+    _port = digitalPinToPort(pin);
+  #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
@@ -46,7 +48,7 @@ float DHT::readTemperature(bool S, bool force) {
       f = data[2] & 0x7F;
       f *= 256;
       f += data[3];
-      f /= 10;
+      f *= 0.1;
       if (data[2] & 0x80) {
         f *= -1;
       }
@@ -60,11 +62,11 @@ float DHT::readTemperature(bool S, bool force) {
 }
 
 float DHT::convertCtoF(float c) {
-  return c * 9 / 5 + 32;
+  return c * 1.8 + 32;
 }
 
 float DHT::convertFtoC(float f) {
-  return (f - 32) * 5 / 9;
+  return (f - 32) * 0.55555;
 }
 
 float DHT::readHumidity(bool force) {
@@ -79,7 +81,7 @@ float DHT::readHumidity(bool force) {
       f = data[0];
       f *= 256;
       f += data[1];
-      f /= 10;
+      f *= 0.1;
       break;
     }
   }

DHT.h

@@ -48,7 +48,12 @@ class DHT {
 
  private:
   uint8_t data[5];
-  uint8_t _pin, _type, _bit, _port;
+  uint8_t _pin, _type;
+  #ifdef __AVR
+    // Use direct GPIO access on an 8-bit AVR so keep track of the port and bitmask
+    // for the digital pin connected to the DHT.  Other platforms will use digitalRead.
+    uint8_t _bit, _port;
+  #endif
   uint32_t _lastreadtime, _maxcycles;
   bool _lastresult;
 

README.md

@@ -1,3 +1,5 @@
 This is an Arduino library for the DHT series of low cost temperature/humidity sensors. 
 
+Tutorial: https://learn.adafruit.com/dht
+
 To download. click the DOWNLOADS button in the top right corner, rename the uncompressed folder DHT. Check that the DHT folder contains DHT.cpp and DHT.h. Place the DHT library folder your <arduinosketchfolder>/libraries/ folder. You may need to create the libraries subfolder if its your first library. Restart the IDE.

examples/DHTtester/DHTtester.ino

@@ -3,11 +3,11 @@
 
 #include "DHT.h"
 
-#define DHTPIN 2     // what pin we're connected to
+#define DHTPIN 2     // what digital pin we're connected to
 
 // Uncomment whatever type you're using!
 //#define DHTTYPE DHT11   // DHT 11
-#define DHTTYPE DHT22   // DHT 22  (AM2302)
+#define DHTTYPE DHT22   // DHT 22  (AM2302), AM2321
 //#define DHTTYPE DHT21   // DHT 21 (AM2301)
 
 // Connect pin 1 (on the left) of the sensor to +5V

library.properties

@@ -1,5 +1,5 @@
 name=DHT sensor library
-version=1.2.1
+version=1.2.3
 author=Adafruit
 maintainer=Adafruit <info@adafruit.com>
 sentence=Arduino library for DHT11, DHT22, etc Temp & Humidity Sensors