Update DHT.h

support 8M arduino

Humidity_Temperature_Sensor/DHT.h

@@ -1,12 +1,22 @@
-#ifndef __DHT_H__
-#define __DHT_H__
+#ifndef DHT_H
+#define DHT_H
 #if ARDUINO >= 100
  #include "Arduino.h"
 #else
  #include "WProgram.h"
 #endif
 
-/* DHT library 
+// 8 MHz(ish) AVR ---------------------------------------------------------
+#if (F_CPU >= 7400000UL) && (F_CPU <= 9500000UL)
+#define COUNT 3
+// 16 MHz(ish) AVR --------------------------------------------------------
+#elif (F_CPU >= 15400000UL) && (F_CPU <= 19000000L)
+#define COUNT 6
+#else
+#error "CPU SPEED NOT SUPPORTED"
+#endif
+
+/* DHT library
 
 MIT license
 written by Adafruit Industries
@@ -20,21 +30,20 @@ written by Adafruit Industries
 #define DHT21 21
 #define AM2301 21
 
-class DHT 
-{
-private:
-    uint8_t data[6];
-    uint8_t _pin, _type, _count;
-    boolean read(void);
-    unsigned long _lastreadtime;
-    boolean firstreading;
-
-public:
-    DHT(uint8_t pin, uint8_t type, uint8_t count=6);
-    void begin(void);
-    float readTemperature(bool S=false);
-    float convertCtoF(float);
-    float readHumidity(void);
-};
+class DHT {
+ private:
+  uint8_t data[6];
+  uint8_t _pin, _type, _count;
+  boolean read(void);
+  unsigned long _lastreadtime;
+  boolean firstreading;
+
+ public:
+  DHT(uint8_t pin, uint8_t type, uint8_t count=COUNT);
+  void begin(void);
+  float readTemperature(bool S=false);
+  float convertCtoF(float);
+  float readHumidity(void);
 
+};
 #endif