DHT.h

/******************************************************************
  DHT Temperature & Humidity Sensor library for Arduino.

  Features:
  - Support for DHT11 and DHT22/AM2302/RHT03
  - Auto detect sensor model
  - Very low memory footprint
  - Very small code

  http://www.github.com/markruys/arduino-DHT

  Written by Mark Ruys, mark@paracas.nl.

  BSD license, check license.txt for more information.
  All text above must be included in any redistribution.

  Datasheets:
  - http://www.micro4you.com/files/sensor/DHT11.pdf
  - http://www.adafruit.com/datasheets/DHT22.pdf
  - http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Sensors/Weather/RHT03.pdf
  - http://meteobox.tk/files/AM2302.pdf

  Changelog:
   2013-06-10: Initial version
   2013-06-12: Refactored code
   2013-07-01: Add a resetTimer method
 ******************************************************************/

#ifndef dht_h
#define dht_h

#if ARDUINO < 100
  #include <WProgram.h>
#else
  #include <Arduino.h>
#endif

class DHT
{
public:

  typedef enum {
    AUTO_DETECT,
    DHT11,
    DHT22,
    AM2302,  // Packaged DHT22
    RHT03    // Equivalent to DHT22
  }
  DHT_MODEL_t;

  typedef enum {
    ERROR_NONE = 0,
    ERROR_TIMEOUT,
    ERROR_CHECKSUM
  }
  DHT_ERROR_t;

  void setup(uint8_t pin, DHT_MODEL_t model=AUTO_DETECT);
  void resetTimer();

  float getTemperature();
  float getHumidity();

  DHT_ERROR_t getStatus() { return error; };
  const char* getStatusString();

  DHT_MODEL_t getModel() { return model; }

  int getMinimumSamplingPeriod() { return model == DHT11 ? 1000 : 2000; }

  int8_t getNumberOfDecimalsTemperature() { return model == DHT11 ? 0 : 1; };
  int8_t getLowerBoundTemperature() { return model == DHT11 ? 0 : -40; };
  int8_t getUpperBoundTemperature() { return model == DHT11 ? 50 : 125; };

  int8_t getNumberOfDecimalsHumidity() { return 0; };
  int8_t getLowerBoundHumidity() { return model == DHT11 ? 20 : 0; };
  int8_t getUpperBoundHumidity() { return model == DHT11 ? 90 : 100; };

  static float toFahrenheit(float fromCelcius) { return 1.8 * fromCelcius + 32.0; };
  static float toCelsius(float fromFahrenheit) { return (fromFahrenheit - 32.0) / 1.8; };

protected:
  void readSensor();

  float temperature;
  float humidity;

  uint8_t pin;

private:
  DHT_MODEL_t model;
  DHT_ERROR_t error;
  unsigned long lastReadTime;
};

#endif /*dht_h*/