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Dependencies:   mbed

Fork of ll14zs by Zeshaan Saeed

Joystick/Joystick.cpp@2:5d3aac7fd3df, 2018-05-08 (annotated)

Committer:
ll14zs
Date:
Tue May 08 11:15:58 2018 +0000
Revision:
2:5d3aac7fd3df
commit before implementing the road;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
ll14zs 2:5d3aac7fd3df 1 #include "Joystick.h"
ll14zs 2:5d3aac7fd3df 2
ll14zs 2:5d3aac7fd3df 3 Joystick::Joystick(PinName vertPin,PinName horizPin,PinName clickPin)
ll14zs 2:5d3aac7fd3df 4 {
ll14zs 2:5d3aac7fd3df 5 vert = new AnalogIn(vertPin);
ll14zs 2:5d3aac7fd3df 6 horiz = new AnalogIn(horizPin);
ll14zs 2:5d3aac7fd3df 7 click = new InterruptIn(clickPin);
ll14zs 2:5d3aac7fd3df 8 }
ll14zs 2:5d3aac7fd3df 9
ll14zs 2:5d3aac7fd3df 10 void Joystick::init()
ll14zs 2:5d3aac7fd3df 11 {
ll14zs 2:5d3aac7fd3df 12 // read centred values of joystick
ll14zs 2:5d3aac7fd3df 13 _x0 = horiz->read();
ll14zs 2:5d3aac7fd3df 14 _y0 = vert->read();
ll14zs 2:5d3aac7fd3df 15
ll14zs 2:5d3aac7fd3df 16 // this assumes that the joystick is centred when the init function is called
ll14zs 2:5d3aac7fd3df 17 // if perfectly centred, the pots should read 0.5, but this may
ll14zs 2:5d3aac7fd3df 18 // not be the case and x0 and y0 will be used to calibrate readings
ll14zs 2:5d3aac7fd3df 19
ll14zs 2:5d3aac7fd3df 20 // turn on pull-down for button -> this assumes the other side of the button
ll14zs 2:5d3aac7fd3df 21 // is connected to +3V3 so we read 1 when pressed and 0 when not pressed
ll14zs 2:5d3aac7fd3df 22 click->mode(PullDown);
ll14zs 2:5d3aac7fd3df 23 // we therefore need to fire the interrupt on a rising edge
ll14zs 2:5d3aac7fd3df 24 click->rise(callback(this,&Joystick::click_isr));
ll14zs 2:5d3aac7fd3df 25 // need to use a callback since mbed-os5 - basically tells it to look in this class for the ISR
ll14zs 2:5d3aac7fd3df 26 _click_flag = 0;
ll14zs 2:5d3aac7fd3df 27
ll14zs 2:5d3aac7fd3df 28 }
ll14zs 2:5d3aac7fd3df 29
ll14zs 2:5d3aac7fd3df 30 Direction Joystick::get_direction()
ll14zs 2:5d3aac7fd3df 31 {
ll14zs 2:5d3aac7fd3df 32 float angle = get_angle(); // 0 to 360, -1 for centred
ll14zs 2:5d3aac7fd3df 33
ll14zs 2:5d3aac7fd3df 34 Direction d;
ll14zs 2:5d3aac7fd3df 35 // partition 360 into segments and check which segment the angle is in
ll14zs 2:5d3aac7fd3df 36 if (angle < 0.0f) {
ll14zs 2:5d3aac7fd3df 37 d = CENTRE; // check for -1.0 angle
ll14zs 2:5d3aac7fd3df 38 } else if (angle < 22.5f) { // then keep going in 45 degree increments
ll14zs 2:5d3aac7fd3df 39 d = N;
ll14zs 2:5d3aac7fd3df 40 } else if (angle < 67.5f) {
ll14zs 2:5d3aac7fd3df 41 d = NE;
ll14zs 2:5d3aac7fd3df 42 } else if (angle < 112.5f) {
ll14zs 2:5d3aac7fd3df 43 d = E;
ll14zs 2:5d3aac7fd3df 44 } else if (angle < 157.5f) {
ll14zs 2:5d3aac7fd3df 45 d = SE;
ll14zs 2:5d3aac7fd3df 46 } else if (angle < 202.5f) {
ll14zs 2:5d3aac7fd3df 47 d = S;
ll14zs 2:5d3aac7fd3df 48 } else if (angle < 247.5f) {
ll14zs 2:5d3aac7fd3df 49 d = SW;
ll14zs 2:5d3aac7fd3df 50 } else if (angle < 292.5f) {
ll14zs 2:5d3aac7fd3df 51 d = W;
ll14zs 2:5d3aac7fd3df 52 } else if (angle < 337.5f) {
ll14zs 2:5d3aac7fd3df 53 d = NW;
ll14zs 2:5d3aac7fd3df 54 } else {
ll14zs 2:5d3aac7fd3df 55 d = N;
ll14zs 2:5d3aac7fd3df 56 }
ll14zs 2:5d3aac7fd3df 57
ll14zs 2:5d3aac7fd3df 58 return d;
ll14zs 2:5d3aac7fd3df 59 }
ll14zs 2:5d3aac7fd3df 60
ll14zs 2:5d3aac7fd3df 61 // this method gets the magnitude of the joystick movement
ll14zs 2:5d3aac7fd3df 62 float Joystick::get_mag()
ll14zs 2:5d3aac7fd3df 63 {
ll14zs 2:5d3aac7fd3df 64 Polar p = get_polar();
ll14zs 2:5d3aac7fd3df 65 return p.mag;
ll14zs 2:5d3aac7fd3df 66 }
ll14zs 2:5d3aac7fd3df 67
ll14zs 2:5d3aac7fd3df 68 // this method gets the angle of joystick movement (0 to 360, 0 North)
ll14zs 2:5d3aac7fd3df 69 float Joystick::get_angle()
ll14zs 2:5d3aac7fd3df 70 {
ll14zs 2:5d3aac7fd3df 71 Polar p = get_polar();
ll14zs 2:5d3aac7fd3df 72 return p.angle;
ll14zs 2:5d3aac7fd3df 73 }
ll14zs 2:5d3aac7fd3df 74
ll14zs 2:5d3aac7fd3df 75 // get raw joystick coordinate in range -1 to 1
ll14zs 2:5d3aac7fd3df 76 // Direction (x,y)
ll14zs 2:5d3aac7fd3df 77 // North (0,1)
ll14zs 2:5d3aac7fd3df 78 // East (1,0)
ll14zs 2:5d3aac7fd3df 79 // South (0,-1)
ll14zs 2:5d3aac7fd3df 80 // West (-1,0)
ll14zs 2:5d3aac7fd3df 81 Vector2D Joystick::get_coord()
ll14zs 2:5d3aac7fd3df 82 {
ll14zs 2:5d3aac7fd3df 83 // read() returns value in range 0.0 to 1.0 so is scaled and centre value
ll14zs 2:5d3aac7fd3df 84 // substracted to get values in the range -1.0 to 1.0
ll14zs 2:5d3aac7fd3df 85 float x = 2.0f*( horiz->read() - _x0 );
ll14zs 2:5d3aac7fd3df 86 float y = 2.0f*( vert->read() - _y0 );
ll14zs 2:5d3aac7fd3df 87
ll14zs 2:5d3aac7fd3df 88 // Note: the x value here is inverted to ensure the positive x is to the
ll14zs 2:5d3aac7fd3df 89 // right. This is simply due to how the potentiometer on the joystick
ll14zs 2:5d3aac7fd3df 90 // I was using was connected up. It could have been corrected in hardware
ll14zs 2:5d3aac7fd3df 91 // by swapping the power supply pins. Instead it is done in software so may
ll14zs 2:5d3aac7fd3df 92 // need to be changed depending on your wiring setup
ll14zs 2:5d3aac7fd3df 93
ll14zs 2:5d3aac7fd3df 94 Vector2D coord = {-x,y};
ll14zs 2:5d3aac7fd3df 95 return coord;
ll14zs 2:5d3aac7fd3df 96 }
ll14zs 2:5d3aac7fd3df 97
ll14zs 2:5d3aac7fd3df 98 // This maps the raw x,y coord onto a circular grid.
ll14zs 2:5d3aac7fd3df 99 // See: http://mathproofs.blogspot.co.uk/2005/07/mapping-square-to-circle.html
ll14zs 2:5d3aac7fd3df 100 Vector2D Joystick::get_mapped_coord()
ll14zs 2:5d3aac7fd3df 101 {
ll14zs 2:5d3aac7fd3df 102 Vector2D coord = get_coord();
ll14zs 2:5d3aac7fd3df 103
ll14zs 2:5d3aac7fd3df 104 // do the transformation
ll14zs 2:5d3aac7fd3df 105 float x = coord.x*sqrt(1.0f-pow(coord.y,2.0f)/2.0f);
ll14zs 2:5d3aac7fd3df 106 float y = coord.y*sqrt(1.0f-pow(coord.x,2.0f)/2.0f);
ll14zs 2:5d3aac7fd3df 107
ll14zs 2:5d3aac7fd3df 108 Vector2D mapped_coord = {x,y};
ll14zs 2:5d3aac7fd3df 109 return mapped_coord;
ll14zs 2:5d3aac7fd3df 110 }
ll14zs 2:5d3aac7fd3df 111
ll14zs 2:5d3aac7fd3df 112 // this function converts the mapped coordinates into polar form
ll14zs 2:5d3aac7fd3df 113 Polar Joystick::get_polar()
ll14zs 2:5d3aac7fd3df 114 {
ll14zs 2:5d3aac7fd3df 115 // get the mapped coordinate
ll14zs 2:5d3aac7fd3df 116 Vector2D coord = get_mapped_coord();
ll14zs 2:5d3aac7fd3df 117
ll14zs 2:5d3aac7fd3df 118 // at this point, 0 degrees (i.e. x-axis) will be defined to the East.
ll14zs 2:5d3aac7fd3df 119 // We want 0 degrees to correspond to North and increase clockwise to 359
ll14zs 2:5d3aac7fd3df 120 // like a compass heading, so we need to swap the axis and invert y
ll14zs 2:5d3aac7fd3df 121 float x = coord.y;
ll14zs 2:5d3aac7fd3df 122 float y = coord.x;
ll14zs 2:5d3aac7fd3df 123
ll14zs 2:5d3aac7fd3df 124 float mag = sqrt(x*x+y*y); // pythagoras
ll14zs 2:5d3aac7fd3df 125 float angle = RAD2DEG*atan2(y,x);
ll14zs 2:5d3aac7fd3df 126 // angle will be in range -180 to 180, so add 360 to negative angles to
ll14zs 2:5d3aac7fd3df 127 // move to 0 to 360 range
ll14zs 2:5d3aac7fd3df 128 if (angle < 0.0f) {
ll14zs 2:5d3aac7fd3df 129 angle+=360.0f;
ll14zs 2:5d3aac7fd3df 130 }
ll14zs 2:5d3aac7fd3df 131
ll14zs 2:5d3aac7fd3df 132 // the noise on the ADC causes the values of x and y to fluctuate slightly
ll14zs 2:5d3aac7fd3df 133 // around the centred values. This causes the random angle values to get
ll14zs 2:5d3aac7fd3df 134 // calculated when the joystick is centred and untouched. This is also when
ll14zs 2:5d3aac7fd3df 135 // the magnitude is very small, so we can check for a small magnitude and then
ll14zs 2:5d3aac7fd3df 136 // set the angle to -1. This will inform us when the angle is invalid and the
ll14zs 2:5d3aac7fd3df 137 // joystick is centred
ll14zs 2:5d3aac7fd3df 138
ll14zs 2:5d3aac7fd3df 139 if (mag < TOL) {
ll14zs 2:5d3aac7fd3df 140 mag = 0.0f;
ll14zs 2:5d3aac7fd3df 141 angle = -1.0f;
ll14zs 2:5d3aac7fd3df 142 }
ll14zs 2:5d3aac7fd3df 143
ll14zs 2:5d3aac7fd3df 144 Polar p = {mag,angle};
ll14zs 2:5d3aac7fd3df 145 return p;
ll14zs 2:5d3aac7fd3df 146 }
ll14zs 2:5d3aac7fd3df 147
ll14zs 2:5d3aac7fd3df 148 bool Joystick::button_pressed()
ll14zs 2:5d3aac7fd3df 149 {
ll14zs 2:5d3aac7fd3df 150 // ISR must have been triggered
ll14zs 2:5d3aac7fd3df 151 if (_click_flag) {
ll14zs 2:5d3aac7fd3df 152 _click_flag = 0; // clear flag
ll14zs 2:5d3aac7fd3df 153 return true;
ll14zs 2:5d3aac7fd3df 154 } else {
ll14zs 2:5d3aac7fd3df 155 return false;
ll14zs 2:5d3aac7fd3df 156 }
ll14zs 2:5d3aac7fd3df 157 }
ll14zs 2:5d3aac7fd3df 158
ll14zs 2:5d3aac7fd3df 159 void Joystick::click_isr()
ll14zs 2:5d3aac7fd3df 160 {
ll14zs 2:5d3aac7fd3df 161 _click_flag = 1;
ll14zs 2:5d3aac7fd3df 162 }