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Coursework
Joystick.cpp@0:1f799c7cce2b, 2021-12-16 (annotated)
- Committer:
- sesa514652
- Date:
- Thu Dec 16 14:03:11 2021 +0000
- Revision:
- 0:1f799c7cce2b
Screen and US combined code
Who changed what in which revision?
User | Revision | Line number | New contents of line |
---|---|---|---|
sesa514652 | 0:1f799c7cce2b | 1 | #include "Joystick.h" |
sesa514652 | 0:1f799c7cce2b | 2 | |
sesa514652 | 0:1f799c7cce2b | 3 | Joystick::Joystick(PinName vertPin,PinName horizPin,PinName clickPin) |
sesa514652 | 0:1f799c7cce2b | 4 | { |
sesa514652 | 0:1f799c7cce2b | 5 | vert = new AnalogIn(vertPin); |
sesa514652 | 0:1f799c7cce2b | 6 | horiz = new AnalogIn(horizPin); |
sesa514652 | 0:1f799c7cce2b | 7 | click = new InterruptIn(clickPin); |
sesa514652 | 0:1f799c7cce2b | 8 | } |
sesa514652 | 0:1f799c7cce2b | 9 | |
sesa514652 | 0:1f799c7cce2b | 10 | void Joystick::init() |
sesa514652 | 0:1f799c7cce2b | 11 | { |
sesa514652 | 0:1f799c7cce2b | 12 | // read centred values of joystick |
sesa514652 | 0:1f799c7cce2b | 13 | _x0 = horiz->read(); |
sesa514652 | 0:1f799c7cce2b | 14 | _y0 = vert->read(); |
sesa514652 | 0:1f799c7cce2b | 15 | |
sesa514652 | 0:1f799c7cce2b | 16 | // this assumes that the joystick is centred when the init function is called |
sesa514652 | 0:1f799c7cce2b | 17 | // if perfectly centred, the pots should read 0.5, but this may |
sesa514652 | 0:1f799c7cce2b | 18 | // not be the case and x0 and y0 will be used to calibrate readings |
sesa514652 | 0:1f799c7cce2b | 19 | |
sesa514652 | 0:1f799c7cce2b | 20 | // turn on pull-down for button -> this assumes the other side of the button |
sesa514652 | 0:1f799c7cce2b | 21 | // is connected to +3V3 so we read 1 when pressed and 0 when not pressed |
sesa514652 | 0:1f799c7cce2b | 22 | click->mode(PullDown); |
sesa514652 | 0:1f799c7cce2b | 23 | // we therefore need to fire the interrupt on a rising edge |
sesa514652 | 0:1f799c7cce2b | 24 | click->rise(callback(this,&Joystick::click_isr)); |
sesa514652 | 0:1f799c7cce2b | 25 | // need to use a callback since mbed-os5 - basically tells it to look in this class for the ISR |
sesa514652 | 0:1f799c7cce2b | 26 | _click_flag = 0; |
sesa514652 | 0:1f799c7cce2b | 27 | |
sesa514652 | 0:1f799c7cce2b | 28 | } |
sesa514652 | 0:1f799c7cce2b | 29 | |
sesa514652 | 0:1f799c7cce2b | 30 | Direction Joystick::get_direction() |
sesa514652 | 0:1f799c7cce2b | 31 | { |
sesa514652 | 0:1f799c7cce2b | 32 | float angle = get_angle(); // 0 to 360, -1 for centred |
sesa514652 | 0:1f799c7cce2b | 33 | |
sesa514652 | 0:1f799c7cce2b | 34 | Direction d; |
sesa514652 | 0:1f799c7cce2b | 35 | // partition 360 into segments and check which segment the angle is in |
sesa514652 | 0:1f799c7cce2b | 36 | if (angle < 0.0f) { |
sesa514652 | 0:1f799c7cce2b | 37 | d = CENTRE; // check for -1.0 angle |
sesa514652 | 0:1f799c7cce2b | 38 | } else if (angle < 22.5f) { // then keep going in 45 degree increments |
sesa514652 | 0:1f799c7cce2b | 39 | d = N; |
sesa514652 | 0:1f799c7cce2b | 40 | } else if (angle < 67.5f) { |
sesa514652 | 0:1f799c7cce2b | 41 | d = NE; |
sesa514652 | 0:1f799c7cce2b | 42 | } else if (angle < 112.5f) { |
sesa514652 | 0:1f799c7cce2b | 43 | d = E; |
sesa514652 | 0:1f799c7cce2b | 44 | } else if (angle < 157.5f) { |
sesa514652 | 0:1f799c7cce2b | 45 | d = SE; |
sesa514652 | 0:1f799c7cce2b | 46 | } else if (angle < 202.5f) { |
sesa514652 | 0:1f799c7cce2b | 47 | d = S; |
sesa514652 | 0:1f799c7cce2b | 48 | } else if (angle < 247.5f) { |
sesa514652 | 0:1f799c7cce2b | 49 | d = SW; |
sesa514652 | 0:1f799c7cce2b | 50 | } else if (angle < 292.5f) { |
sesa514652 | 0:1f799c7cce2b | 51 | d = W; |
sesa514652 | 0:1f799c7cce2b | 52 | } else if (angle < 337.5f) { |
sesa514652 | 0:1f799c7cce2b | 53 | d = NW; |
sesa514652 | 0:1f799c7cce2b | 54 | } else { |
sesa514652 | 0:1f799c7cce2b | 55 | d = N; |
sesa514652 | 0:1f799c7cce2b | 56 | } |
sesa514652 | 0:1f799c7cce2b | 57 | |
sesa514652 | 0:1f799c7cce2b | 58 | return d; |
sesa514652 | 0:1f799c7cce2b | 59 | } |
sesa514652 | 0:1f799c7cce2b | 60 | |
sesa514652 | 0:1f799c7cce2b | 61 | // this method gets the magnitude of the joystick movement |
sesa514652 | 0:1f799c7cce2b | 62 | float Joystick::get_mag() |
sesa514652 | 0:1f799c7cce2b | 63 | { |
sesa514652 | 0:1f799c7cce2b | 64 | Polar p = get_polar(); |
sesa514652 | 0:1f799c7cce2b | 65 | return p.mag; |
sesa514652 | 0:1f799c7cce2b | 66 | } |
sesa514652 | 0:1f799c7cce2b | 67 | |
sesa514652 | 0:1f799c7cce2b | 68 | // this method gets the angle of joystick movement (0 to 360, 0 North) |
sesa514652 | 0:1f799c7cce2b | 69 | float Joystick::get_angle() |
sesa514652 | 0:1f799c7cce2b | 70 | { |
sesa514652 | 0:1f799c7cce2b | 71 | Polar p = get_polar(); |
sesa514652 | 0:1f799c7cce2b | 72 | return p.angle; |
sesa514652 | 0:1f799c7cce2b | 73 | } |
sesa514652 | 0:1f799c7cce2b | 74 | |
sesa514652 | 0:1f799c7cce2b | 75 | // get raw joystick coordinate in range -1 to 1 |
sesa514652 | 0:1f799c7cce2b | 76 | // Direction (x,y) |
sesa514652 | 0:1f799c7cce2b | 77 | // North (0,1) |
sesa514652 | 0:1f799c7cce2b | 78 | // East (1,0) |
sesa514652 | 0:1f799c7cce2b | 79 | // South (0,-1) |
sesa514652 | 0:1f799c7cce2b | 80 | // West (-1,0) |
sesa514652 | 0:1f799c7cce2b | 81 | Vector2D Joystick::get_coord() |
sesa514652 | 0:1f799c7cce2b | 82 | { |
sesa514652 | 0:1f799c7cce2b | 83 | // read() returns value in range 0.0 to 1.0 so is scaled and centre value |
sesa514652 | 0:1f799c7cce2b | 84 | // substracted to get values in the range -1.0 to 1.0 |
sesa514652 | 0:1f799c7cce2b | 85 | float x = 2.0f*( horiz->read() - _x0 ); |
sesa514652 | 0:1f799c7cce2b | 86 | float y = 2.0f*( vert->read() - _y0 ); |
sesa514652 | 0:1f799c7cce2b | 87 | |
sesa514652 | 0:1f799c7cce2b | 88 | // Note: the x value here is inverted to ensure the positive x is to the |
sesa514652 | 0:1f799c7cce2b | 89 | // right. This is simply due to how the potentiometer on the joystick |
sesa514652 | 0:1f799c7cce2b | 90 | // I was using was connected up. It could have been corrected in hardware |
sesa514652 | 0:1f799c7cce2b | 91 | // by swapping the power supply pins. Instead it is done in software so may |
sesa514652 | 0:1f799c7cce2b | 92 | // need to be changed depending on your wiring setup |
sesa514652 | 0:1f799c7cce2b | 93 | |
sesa514652 | 0:1f799c7cce2b | 94 | Vector2D coord = {-x,y}; |
sesa514652 | 0:1f799c7cce2b | 95 | return coord; |
sesa514652 | 0:1f799c7cce2b | 96 | } |
sesa514652 | 0:1f799c7cce2b | 97 | |
sesa514652 | 0:1f799c7cce2b | 98 | // This maps the raw x,y coord onto a circular grid. |
sesa514652 | 0:1f799c7cce2b | 99 | // See: http://mathproofs.blogspot.co.uk/2005/07/mapping-square-to-circle.html |
sesa514652 | 0:1f799c7cce2b | 100 | Vector2D Joystick::get_mapped_coord() |
sesa514652 | 0:1f799c7cce2b | 101 | { |
sesa514652 | 0:1f799c7cce2b | 102 | Vector2D coord = get_coord(); |
sesa514652 | 0:1f799c7cce2b | 103 | |
sesa514652 | 0:1f799c7cce2b | 104 | // do the transformation |
sesa514652 | 0:1f799c7cce2b | 105 | float x = coord.x*sqrt(1.0f-pow(coord.y,2.0f)/2.0f); |
sesa514652 | 0:1f799c7cce2b | 106 | float y = coord.y*sqrt(1.0f-pow(coord.x,2.0f)/2.0f); |
sesa514652 | 0:1f799c7cce2b | 107 | |
sesa514652 | 0:1f799c7cce2b | 108 | Vector2D mapped_coord = {x,y}; |
sesa514652 | 0:1f799c7cce2b | 109 | return mapped_coord; |
sesa514652 | 0:1f799c7cce2b | 110 | } |
sesa514652 | 0:1f799c7cce2b | 111 | |
sesa514652 | 0:1f799c7cce2b | 112 | // this function converts the mapped coordinates into polar form |
sesa514652 | 0:1f799c7cce2b | 113 | Polar Joystick::get_polar() |
sesa514652 | 0:1f799c7cce2b | 114 | { |
sesa514652 | 0:1f799c7cce2b | 115 | // get the mapped coordinate |
sesa514652 | 0:1f799c7cce2b | 116 | Vector2D coord = get_mapped_coord(); |
sesa514652 | 0:1f799c7cce2b | 117 | |
sesa514652 | 0:1f799c7cce2b | 118 | // at this point, 0 degrees (i.e. x-axis) will be defined to the East. |
sesa514652 | 0:1f799c7cce2b | 119 | // We want 0 degrees to correspond to North and increase clockwise to 359 |
sesa514652 | 0:1f799c7cce2b | 120 | // like a compass heading, so we need to swap the axis and invert y |
sesa514652 | 0:1f799c7cce2b | 121 | float x = coord.y; |
sesa514652 | 0:1f799c7cce2b | 122 | float y = coord.x; |
sesa514652 | 0:1f799c7cce2b | 123 | |
sesa514652 | 0:1f799c7cce2b | 124 | float mag = sqrt(x*x+y*y); // pythagoras |
sesa514652 | 0:1f799c7cce2b | 125 | float angle = RAD2DEG*atan2(y,x); |
sesa514652 | 0:1f799c7cce2b | 126 | // angle will be in range -180 to 180, so add 360 to negative angles to |
sesa514652 | 0:1f799c7cce2b | 127 | // move to 0 to 360 range |
sesa514652 | 0:1f799c7cce2b | 128 | if (angle < 0.0f) { |
sesa514652 | 0:1f799c7cce2b | 129 | angle+=360.0f; |
sesa514652 | 0:1f799c7cce2b | 130 | } |
sesa514652 | 0:1f799c7cce2b | 131 | |
sesa514652 | 0:1f799c7cce2b | 132 | // the noise on the ADC causes the values of x and y to fluctuate slightly |
sesa514652 | 0:1f799c7cce2b | 133 | // around the centred values. This causes the random angle values to get |
sesa514652 | 0:1f799c7cce2b | 134 | // calculated when the joystick is centred and untouched. This is also when |
sesa514652 | 0:1f799c7cce2b | 135 | // the magnitude is very small, so we can check for a small magnitude and then |
sesa514652 | 0:1f799c7cce2b | 136 | // set the angle to -1. This will inform us when the angle is invalid and the |
sesa514652 | 0:1f799c7cce2b | 137 | // joystick is centred |
sesa514652 | 0:1f799c7cce2b | 138 | |
sesa514652 | 0:1f799c7cce2b | 139 | if (mag < TOL) { |
sesa514652 | 0:1f799c7cce2b | 140 | mag = 0.0f; |
sesa514652 | 0:1f799c7cce2b | 141 | angle = -1.0f; |
sesa514652 | 0:1f799c7cce2b | 142 | } |
sesa514652 | 0:1f799c7cce2b | 143 | |
sesa514652 | 0:1f799c7cce2b | 144 | Polar p = {mag,angle}; |
sesa514652 | 0:1f799c7cce2b | 145 | return p; |
sesa514652 | 0:1f799c7cce2b | 146 | } |
sesa514652 | 0:1f799c7cce2b | 147 | |
sesa514652 | 0:1f799c7cce2b | 148 | bool Joystick::button_pressed() |
sesa514652 | 0:1f799c7cce2b | 149 | { |
sesa514652 | 0:1f799c7cce2b | 150 | // ISR must have been triggered |
sesa514652 | 0:1f799c7cce2b | 151 | if (_click_flag) { |
sesa514652 | 0:1f799c7cce2b | 152 | _click_flag = 0; // clear flag |
sesa514652 | 0:1f799c7cce2b | 153 | return true; |
sesa514652 | 0:1f799c7cce2b | 154 | } else { |
sesa514652 | 0:1f799c7cce2b | 155 | return false; |
sesa514652 | 0:1f799c7cce2b | 156 | } |
sesa514652 | 0:1f799c7cce2b | 157 | } |
sesa514652 | 0:1f799c7cce2b | 158 | |
sesa514652 | 0:1f799c7cce2b | 159 | void Joystick::click_isr() |
sesa514652 | 0:1f799c7cce2b | 160 | { |
sesa514652 | 0:1f799c7cce2b | 161 | _click_flag = 1; |
sesa514652 | 0:1f799c7cce2b | 162 | } |
sesa514652 | 0:1f799c7cce2b | 163 |