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/**
 * @author Hugues Angelis
 *
 * @section LICENSE
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation 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
 * furnished 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 FOR 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.
 *
 * @section DESCRIPTION
 *
 * Vellerman VMA306 Ultrasonic Range Finder Library
 *
 * @Note :
 *  The purpose of this library is to adapt SRF05 library to allow full control of the sensor : 
 *      - allow cycle control (time between 2 pulses)
 *      - delayed trigerring (start periodical mesurement with a delay) 
 *  because in case of multiple US sensor use, pulse from a sensor can be detected by another like its own echo and thus interfere with mesurement.
 *
 *  Cycle time must be greater or equal to 50ms.
 *  After 30ms the sensor times out so 30ms output pulse means no detection
 *
 *  You may divide the echo pulse width by 58µs/cm to calculate the almost exact distance to the obstacle in centimeters.
 *
 *  To allow non blocking read you may use the global variable VMA306Flag witch is set to one each time a new mesure is ready. This variable must be cleared by user
 */

#ifndef _VMA306_H
#define _VMA306_H

/**
 * Includes : Mbed Library
 */
#include "mbed.h"

/**
 * VMA306 Ultrasonic Range Finder
 * similar to SRF05 : https://www.robot-electronics.co.uk/htm/srf05tech.htm
 * Poor documentation can be found here (FR) : https://www.gotronic.fr/art-capteur-a-ultrasons-vma306-26096.htm
 */
class VMA306 {
public:

    /** Constructor : Create a VMA306 object, connected to the specified pins
     *
     * @param trigger : DigitalOut to the VMA306 trigger
     * @param echo : InterruptIn to measure the return pulse
     */
    VMA306(PinName trigger, PinName echo);
    
    /** Start periodic Trigger
     *
     *  @param period : float time in second between two trig pulses
     *
     *  @note This function allows user to start each instance of Ultra Sonic range finder with a delay from the others (delay managment must be done by users).
     *  @note The first pulse will be send 1 period after.
     */
    void startPeriodicTrigger (float period = 0.15);
    
    /** Gives indication of a new mesurement
     *
     *  @return 1 if new data is ready, else 0
     */
    int isDataReady ();
    
    /** A non-blocking function that will return the last measurement
     *
     * @returns floating point representation of distance in cm
     */
    float read();

    /** A short hand way of using the read function */
    operator float();
        
private :
    DigitalOut _trigger;
    InterruptIn _echo;
    Timer _timer;
    Ticker _ticker;
    void _rising (void);
    void _falling (void);
    void _startRange (void);
    float _dist;
    int _VMA306Flag;
};

#endif