File content as of revision 4:0c34c98a87ec:

/*
 *  DHT Library for  Digital-output Humidity and Temperature sensors
 *
 *  Works with DHT11, DHT21, DHT22
 *             SEN11301P,  Grove - Temperature&Humidity Sensor     (Seeed Studio)
 *             SEN51035P,  Grove - Temperature&Humidity Sensor Pro (Seeed Studio)
 *             AM2302   ,  temperature-humidity sensor
 *             RHT01,RHT02, RHT03, Humidity and Temperature Sensor (Sparkfun)
 *
 *  Copyright (C) Wim De Roeve
 *                based on DHT22 sensor library by HO WING KIT
 *                Arduino DHT11 library
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documnetation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to  whom the Software is
 * furished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS OR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 * /////////////////////////////////////////////////////////////////////////////
 *
 * Used by Giorgos Tsapparellas for Internet of Things (IoT) smart monitoring
 * device for agriculture using LoRaWAN technology.
 * 
 * Sensor Used: DHT11 - Digital-output Humidity and Temperature sensor.
 *
 * Date of issued copy: 10 January 2018
 *
 * Modifications: 
 * - No external modifications of the existing "AS IT IS" software.
 * - Added some external comments for meeting good principles of 
 *   source code re-usability.   
 */

#ifndef MBED_DHT_H
#define MBED_DHT_H

#include "mbed.h"

// eType data structure regarding sensor selection (either 11 or 22 value).
typedef enum eType eType;
enum eType {
    DHT11     = 11,
    SEN11301P = 11,
    RHT01     = 11,
    DHT22     = 22,
    AM2302    = 22,
    SEN51035P = 22,
    RHT02     = 22,
    RHT03     = 22
};

// eError enumeration regarding possible sensor's errors (from 0 to 7).  
typedef enum eError eError;
enum eError {
    ERROR_NONE = 0,
    BUS_BUSY,
    ERROR_NOT_PRESENT,
    ERROR_ACK_TOO_LONG,
    ERROR_SYNC_TIMEOUT,
    ERROR_DATA_TIMEOUT,
    ERROR_CHECKSUM,
    ERROR_NO_PATIENCE
};

// eScale enumeration for possible temperature's scales (from 0 to 3=2). 
typedef enum eScale eScale;
enum eScale {
    CELCIUS = 0,
    FARENHEIT,
    KELVIN
};

/* Public and private declarations of DHT class. */
class DHT
{
/* Public function callbacks of DHT class. */
public:

    DHT(PinName pin, eType DHTtype);
    ~DHT();
    eError readData(void);
    float ReadHumidity(void);
    float ReadTemperature(eScale const Scale);
    float CalcdewPoint(float const celsius, float const humidity);
    float CalcdewPointFast(float const celsius, float const humidity);

/* Private variables declarations and function callbacks of DHT class. */
private:
    time_t  _lastReadTime;
    float _lastTemperature;
    float _lastHumidity;
    PinName _pin;
    bool _firsttime;
    eType _DHTtype;
    uint8_t DHT_data[5];
    float CalcTemperature();
    float CalcHumidity();
    float ConvertCelciustoFarenheit(float const);
    float ConvertCelciustoKelvin(float const);
    eError stall(DigitalInOut &io, int const level, int const max_time);

};

#endif