SparkfunAnalogJoystick.cpp

00001 /** Analog Joystick APIs
00002  *  Used as a user interface for Sparkfun Analog Joystick Module
00003  *  @file SparkfunAnalogJoystick.cpp
00004  *  @author Yuan,ZHANG; Jiajie,YANG
00005  */
00006 
00007 #include "SparkfunAnalogJoystick.h"
00008 #include "math.h"
00009 
00010 #define M_PI 3.14159265358979323846
00011 
00012 /** Constructor of Joystick object
00013  */
00014 SparkfunAnalogJoystick::SparkfunAnalogJoystick(PinName vert, PinName horz, PinName sel): VERT(vert), HORZ(horz), SEL(sel)
00015 {
00016     SEL.mode(PullUp);
00017 }
00018 
00019 //! Get the button status
00020 int SparkfunAnalogJoystick::button(){
00021     return 1-SEL;
00022 }
00023 
00024 //! X axis value, reverse the value to get the x value in a normal Cartesian coordinate system
00025 float SparkfunAnalogJoystick::xAxis(){
00026     return -(HORZ-0.5)*2;
00027 }
00028 
00029 //! Y axis value
00030 float SparkfunAnalogJoystick::yAxis(){
00031     return (VERT-0.5)*2;
00032 }
00033 
00034 //! Calculate the angle value in a polar coordinate system
00035 float SparkfunAnalogJoystick::angle(){
00036     float horz=-(HORZ-0.5)*2;
00037     float vert=(VERT-0.5)*2;
00038     float angle=0;
00039     if (vert==0&&horz>0) return 0;
00040     if (vert==0&&horz<0) return 180;
00041     if (horz==0&&vert>0) return 90;
00042     if (horz==0&&vert<0) return 270;
00043     if (horz>0) angle=atan(vert/horz)*180/M_PI;
00044     else angle=180+atan(vert/horz)*180/M_PI;
00045     if (angle<0) angle+=360;
00046     return angle;
00047 }
00048 
00049 //! Calculate the normalized distance value in a polar coordinate system
00050 float SparkfunAnalogJoystick::distance(){
00051     float horz=-(HORZ-0.5)*2;
00052     float vert=(VERT-0.5)*2;
00053     float angle=SparkfunAnalogJoystick::angle();
00054     float oneAxis=tan(angle*M_PI/180.0);
00055     if (oneAxis<0) oneAxis=-oneAxis;
00056     if (oneAxis>1) oneAxis=1/oneAxis;
00057     float maxdistance=sqrt(1+oneAxis*oneAxis);
00058     float temp=horz*horz+vert*vert;
00059     return sqrt(temp)/maxdistance;
00060     
00061 }