GP2A.h

00001 /**
00002  * @author Hugues Angelis
00003  *
00004  * @section LICENSE
00005  *
00006  * Permission is hereby granted, free of charge, to any person obtaining a copy
00007  * of this software and associated documentation files (the "Software"), to deal
00008  * in the Software without restriction, including without limitation the rights
00009  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00010  * copies of the Software, and to permit persons to whom the Software is
00011  * furnished to do so, subject to the following conditions:
00012  *
00013  * The above copyright notice and this permission notice shall be included in
00014  * all copies or substantial portions of the Software.
00015  *
00016  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00017  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00018  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
00019  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00020  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00021  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00022  * THE SOFTWARE.
00023  *
00024  * @section DESCRIPTION
00025  *
00026  * SHARP GP2 Analog sensor familly library
00027  *
00028  * Any GP2 analog sensor may be added to this library using the constructor :
00029  *      minDistance :   is the minimum distance for linear approximation (cm)
00030  *      maxDistance :   is the maximum distance for linear approximation (cm)
00031  *      slope :         is the slope of the linear part of the graph V = f(1/d)
00032  *                      take special care that we use the 1/d instead of d for x
00033  *                      axis.
00034  *      origin :        is the value of the origin (Y for X = 0) of the line of 
00035  *                      V=f(1/d)
00036  *  The slope parameter must be computed by user unless the GP2 reference is
00037  *  listed in the list below :
00038  *      - GP2Y0A02YK0F (Min = 30cm, Max = 150cm, Slope = 60, origin = 0)
00039  *      - GP2Y0A21YK0F (Min =  7cm, Max =  80cm, Slope = 0.246, origin = -0.297)
00040  *
00041  *  You may add others sensors if you wish it
00042  *
00043  *  One must be aware that under the minimum distance the sensor will output
00044  *  a false value of distance leading to strong errors.
00045  * @endsection
00046  */
00047 
00048 #ifndef GP2A_H
00049 #define GP2A_H
00050 
00051 /**
00052  * Slope definitions for common GP2A sensors
00053  */
00054  
00055 #define GP2Y0A02YK0F_SLOPE    60.0
00056 #define GP2Y0A21YK0F_SLOPE    0.23625
00057 #define GP2Y0A02YK0F_ORIGIN   0.0
00058 #define GP2Y0A21YK0F_ORIGIN   -0.297
00059 
00060 /**
00061  * Includes : Mbed library
00062  */
00063 #include "mbed.h"
00064 
00065 /**
00066  * GP2A Sensor : See sharp website for more informations
00067  *  http://www.sharp-world.com/products/device/lineup/selection/opto/haca/diagram.html
00068  *  @param slope = 60 for a GP2Y0A02 and 0.236 for a GP2Y0A21
00069  *  @param origin = 0 for a GP2Y0A02 and -0.297 for a GP2Y0A21
00070  */
00071 class GP2A {
00072 
00073 public :
00074 
00075     /**
00076      * Constructor of a Sharp GP2 Familly object.
00077      *
00078      * @param vmes (PinName) : the Mbed pin used to connect with GP2A sensor
00079      * @param dMin (double) : the GP2A sensor min distance to mesure
00080      * @param dMax (double) : the GP2A sensor max distance to mesure
00081      * @param slope (double) : the slope of the linear part of the graph V = f(1/d)
00082      * @param origin (double) : the origin (Y for X=0) of the linear pat of the graph V = f(1/d)
00083      * @note you better use slope and origin value that I've put above as sybolic constants
00084      */
00085     GP2A(PinName vmes, float dMin, float dMax, float slope, float origin = 0);
00086 
00087     /**
00088      * Return the distance to target mesured by sensor in cm
00089      *
00090      * @return Distance in cm
00091      * @note Distance is (very) approximative, to have a better mesurment I recommand an averaging of at least 5 measures
00092      * @note you may get a new mesurment every 50ms 
00093      */
00094     double getDistance (void);
00095 
00096     /**
00097      * Return the current voltage on GP2A output
00098      *
00099      * @return Voltage between 0 and 3.3V
00100      */
00101     double getVoltage (void);
00102     
00103     /** 
00104      * A short hand of getDistance
00105      */
00106     operator double();
00107     
00108     
00109 
00110 private :
00111     float m_dMin, m_dMax, m_slope, m_origin;
00112 
00113 protected :
00114 
00115     AnalogIn    _sensor ;
00116 
00117 };
00118 #endif //GP2A_H