(DA) Internet of Things and Smart Electronics- ELE3006M2122 / Mbed 2 deprecated Final_Project_V19_DLeaming_25574043

Final tidy of code following installation of new sensor, more comments added prior to submission

Dependencies:   mbed

Joystick/Joystick.cpp@18:fc63b51a0302, 2022-02-04 (annotated)

Committer:
legstar85
Date:
Fri Feb 04 09:20:18 2022 +0000
Revision:
18:fc63b51a0302
Parent:
13:5ad65a688f3f 
Final tidy of code following installation of new sensor, more comments added prior to submission

Who changed what in which revision?

UserRevisionLine numberNew contents of line
legstar85 13:5ad65a688f3f 1 #include "Joystick.h"
legstar85 13:5ad65a688f3f 2
legstar85 13:5ad65a688f3f 3 Joystick::Joystick(PinName vertPin,PinName horizPin,PinName clickPin)
legstar85 13:5ad65a688f3f 4 {
legstar85 13:5ad65a688f3f 5 vert = new AnalogIn(vertPin);
legstar85 13:5ad65a688f3f 6 horiz = new AnalogIn(horizPin);
legstar85 13:5ad65a688f3f 7 click = new InterruptIn(clickPin);
legstar85 13:5ad65a688f3f 8 }
legstar85 13:5ad65a688f3f 9
legstar85 13:5ad65a688f3f 10 void Joystick::init()
legstar85 13:5ad65a688f3f 11 {
legstar85 13:5ad65a688f3f 12 // read centred values of joystick
legstar85 13:5ad65a688f3f 13 _x0 = horiz->read();
legstar85 13:5ad65a688f3f 14 _y0 = vert->read();
legstar85 13:5ad65a688f3f 15
legstar85 13:5ad65a688f3f 16 // this assumes that the joystick is centred when the init function is called
legstar85 13:5ad65a688f3f 17 // if perfectly centred, the pots should read 0.5, but this may
legstar85 13:5ad65a688f3f 18 // not be the case and x0 and y0 will be used to calibrate readings
legstar85 13:5ad65a688f3f 19
legstar85 13:5ad65a688f3f 20 // turn on pull-down for button -> this assumes the other side of the button
legstar85 13:5ad65a688f3f 21 // is connected to +3V3 so we read 1 when pressed and 0 when not pressed
legstar85 13:5ad65a688f3f 22 click->mode(PullDown);
legstar85 13:5ad65a688f3f 23 // we therefore need to fire the interrupt on a rising edge
legstar85 13:5ad65a688f3f 24 click->rise(callback(this,&Joystick::click_isr));
legstar85 13:5ad65a688f3f 25 // need to use a callback since mbed-os5 - basically tells it to look in this class for the ISR
legstar85 13:5ad65a688f3f 26 _click_flag = 0;
legstar85 13:5ad65a688f3f 27
legstar85 13:5ad65a688f3f 28 }
legstar85 13:5ad65a688f3f 29
legstar85 13:5ad65a688f3f 30 Direction Joystick::get_direction()
legstar85 13:5ad65a688f3f 31 {
legstar85 13:5ad65a688f3f 32 float angle = get_angle(); // 0 to 360, -1 for centred
legstar85 13:5ad65a688f3f 33
legstar85 13:5ad65a688f3f 34 Direction d;
legstar85 13:5ad65a688f3f 35 // partition 360 into segments and check which segment the angle is in
legstar85 13:5ad65a688f3f 36 if (angle < 0.0f) {
legstar85 13:5ad65a688f3f 37 d = CENTRE; // check for -1.0 angle
legstar85 13:5ad65a688f3f 38 } else if (angle < 22.5f) { // then keep going in 45 degree increments
legstar85 13:5ad65a688f3f 39 d = N;
legstar85 13:5ad65a688f3f 40 } else if (angle < 67.5f) {
legstar85 13:5ad65a688f3f 41 d = NE;
legstar85 13:5ad65a688f3f 42 } else if (angle < 112.5f) {
legstar85 13:5ad65a688f3f 43 d = E;
legstar85 13:5ad65a688f3f 44 } else if (angle < 157.5f) {
legstar85 13:5ad65a688f3f 45 d = SE;
legstar85 13:5ad65a688f3f 46 } else if (angle < 202.5f) {
legstar85 13:5ad65a688f3f 47 d = S;
legstar85 13:5ad65a688f3f 48 } else if (angle < 247.5f) {
legstar85 13:5ad65a688f3f 49 d = SW;
legstar85 13:5ad65a688f3f 50 } else if (angle < 292.5f) {
legstar85 13:5ad65a688f3f 51 d = W;
legstar85 13:5ad65a688f3f 52 } else if (angle < 337.5f) {
legstar85 13:5ad65a688f3f 53 d = NW;
legstar85 13:5ad65a688f3f 54 } else {
legstar85 13:5ad65a688f3f 55 d = N;
legstar85 13:5ad65a688f3f 56 }
legstar85 13:5ad65a688f3f 57
legstar85 13:5ad65a688f3f 58 return d;
legstar85 13:5ad65a688f3f 59 }
legstar85 13:5ad65a688f3f 60
legstar85 13:5ad65a688f3f 61 // this method gets the magnitude of the joystick movement
legstar85 13:5ad65a688f3f 62 float Joystick::get_mag()
legstar85 13:5ad65a688f3f 63 {
legstar85 13:5ad65a688f3f 64 Polar p = get_polar();
legstar85 13:5ad65a688f3f 65 return p.mag;
legstar85 13:5ad65a688f3f 66 }
legstar85 13:5ad65a688f3f 67
legstar85 13:5ad65a688f3f 68 // this method gets the angle of joystick movement (0 to 360, 0 North)
legstar85 13:5ad65a688f3f 69 float Joystick::get_angle()
legstar85 13:5ad65a688f3f 70 {
legstar85 13:5ad65a688f3f 71 Polar p = get_polar();
legstar85 13:5ad65a688f3f 72 return p.angle;
legstar85 13:5ad65a688f3f 73 }
legstar85 13:5ad65a688f3f 74
legstar85 13:5ad65a688f3f 75 // get raw joystick coordinate in range -1 to 1
legstar85 13:5ad65a688f3f 76 // Direction (x,y)
legstar85 13:5ad65a688f3f 77 // North (0,1)
legstar85 13:5ad65a688f3f 78 // East (1,0)
legstar85 13:5ad65a688f3f 79 // South (0,-1)
legstar85 13:5ad65a688f3f 80 // West (-1,0)
legstar85 13:5ad65a688f3f 81 Vector2D Joystick::get_coord()
legstar85 13:5ad65a688f3f 82 {
legstar85 13:5ad65a688f3f 83 // read() returns value in range 0.0 to 1.0 so is scaled and centre value
legstar85 13:5ad65a688f3f 84 // substracted to get values in the range -1.0 to 1.0
legstar85 13:5ad65a688f3f 85 float x = 2.0f*( horiz->read() - _x0 );
legstar85 13:5ad65a688f3f 86 float y = 2.0f*( vert->read() - _y0 );
legstar85 13:5ad65a688f3f 87
legstar85 13:5ad65a688f3f 88 // Note: the x value here is inverted to ensure the positive x is to the
legstar85 13:5ad65a688f3f 89 // right. This is simply due to how the potentiometer on the joystick
legstar85 13:5ad65a688f3f 90 // I was using was connected up. It could have been corrected in hardware
legstar85 13:5ad65a688f3f 91 // by swapping the power supply pins. Instead it is done in software so may
legstar85 13:5ad65a688f3f 92 // need to be changed depending on your wiring setup
legstar85 13:5ad65a688f3f 93
legstar85 13:5ad65a688f3f 94 Vector2D coord = {-x,y};
legstar85 13:5ad65a688f3f 95 return coord;
legstar85 13:5ad65a688f3f 96 }
legstar85 13:5ad65a688f3f 97
legstar85 13:5ad65a688f3f 98 // This maps the raw x,y coord onto a circular grid.
legstar85 13:5ad65a688f3f 99 // See: http://mathproofs.blogspot.co.uk/2005/07/mapping-square-to-circle.html
legstar85 13:5ad65a688f3f 100 Vector2D Joystick::get_mapped_coord()
legstar85 13:5ad65a688f3f 101 {
legstar85 13:5ad65a688f3f 102 Vector2D coord = get_coord();
legstar85 13:5ad65a688f3f 103
legstar85 13:5ad65a688f3f 104 // do the transformation
legstar85 13:5ad65a688f3f 105 float x = coord.x*sqrt(1.0f-pow(coord.y,2.0f)/2.0f);
legstar85 13:5ad65a688f3f 106 float y = coord.y*sqrt(1.0f-pow(coord.x,2.0f)/2.0f);
legstar85 13:5ad65a688f3f 107
legstar85 13:5ad65a688f3f 108 Vector2D mapped_coord = {x,y};
legstar85 13:5ad65a688f3f 109 return mapped_coord;
legstar85 13:5ad65a688f3f 110 }
legstar85 13:5ad65a688f3f 111
legstar85 13:5ad65a688f3f 112 // this function converts the mapped coordinates into polar form
legstar85 13:5ad65a688f3f 113 Polar Joystick::get_polar()
legstar85 13:5ad65a688f3f 114 {
legstar85 13:5ad65a688f3f 115 // get the mapped coordinate
legstar85 13:5ad65a688f3f 116 Vector2D coord = get_mapped_coord();
legstar85 13:5ad65a688f3f 117
legstar85 13:5ad65a688f3f 118 // at this point, 0 degrees (i.e. x-axis) will be defined to the East.
legstar85 13:5ad65a688f3f 119 // We want 0 degrees to correspond to North and increase clockwise to 359
legstar85 13:5ad65a688f3f 120 // like a compass heading, so we need to swap the axis and invert y
legstar85 13:5ad65a688f3f 121 float x = coord.y;
legstar85 13:5ad65a688f3f 122 float y = coord.x;
legstar85 13:5ad65a688f3f 123
legstar85 13:5ad65a688f3f 124 float mag = sqrt(x*x+y*y); // pythagoras
legstar85 13:5ad65a688f3f 125 float angle = RAD2DEG*atan2(y,x);
legstar85 13:5ad65a688f3f 126 // angle will be in range -180 to 180, so add 360 to negative angles to
legstar85 13:5ad65a688f3f 127 // move to 0 to 360 range
legstar85 13:5ad65a688f3f 128 if (angle < 0.0f) {
legstar85 13:5ad65a688f3f 129 angle+=360.0f;
legstar85 13:5ad65a688f3f 130 }
legstar85 13:5ad65a688f3f 131
legstar85 13:5ad65a688f3f 132 // the noise on the ADC causes the values of x and y to fluctuate slightly
legstar85 13:5ad65a688f3f 133 // around the centred values. This causes the random angle values to get
legstar85 13:5ad65a688f3f 134 // calculated when the joystick is centred and untouched. This is also when
legstar85 13:5ad65a688f3f 135 // the magnitude is very small, so we can check for a small magnitude and then
legstar85 13:5ad65a688f3f 136 // set the angle to -1. This will inform us when the angle is invalid and the
legstar85 13:5ad65a688f3f 137 // joystick is centred
legstar85 13:5ad65a688f3f 138
legstar85 13:5ad65a688f3f 139 if (mag < TOL) {
legstar85 13:5ad65a688f3f 140 mag = 0.0f;
legstar85 13:5ad65a688f3f 141 angle = -1.0f;
legstar85 13:5ad65a688f3f 142 }
legstar85 13:5ad65a688f3f 143
legstar85 13:5ad65a688f3f 144 Polar p = {mag,angle};
legstar85 13:5ad65a688f3f 145 return p;
legstar85 13:5ad65a688f3f 146 }
legstar85 13:5ad65a688f3f 147
legstar85 13:5ad65a688f3f 148 bool Joystick::button_pressed()
legstar85 13:5ad65a688f3f 149 {
legstar85 13:5ad65a688f3f 150 // ISR must have been triggered
legstar85 13:5ad65a688f3f 151 if (_click_flag) {
legstar85 13:5ad65a688f3f 152 _click_flag = 0; // clear flag
legstar85 13:5ad65a688f3f 153 return true;
legstar85 13:5ad65a688f3f 154 } else {
legstar85 13:5ad65a688f3f 155 return false;
legstar85 13:5ad65a688f3f 156 }
legstar85 13:5ad65a688f3f 157 }
legstar85 13:5ad65a688f3f 158
legstar85 13:5ad65a688f3f 159 void Joystick::click_isr()
legstar85 13:5ad65a688f3f 160 {
legstar85 13:5ad65a688f3f 161 _click_flag = 1;
legstar85 13:5ad65a688f3f 162 }