Meurig Phillips / Joystick

functions for reading the joystick

Dependents:   SnakeProjectRev1 SnakeProjectRev1

Joystick.h@3:ae04f59e274a, 2016-05-05 (annotated)

Committer:
meurigp
Date:
Thu May 05 14:19:34 2016 +0000
Revision:
3:ae04f59e274a
Parent:
2:e444008676a4 
Neater code

Who changed what in which revision?

UserRevisionLine numberNew contents of line
meurigp 0:18c9492be42e 1 #ifndef JOYSTICK_H
meurigp 0:18c9492be42e 2 #define JOYSTICK_H
meurigp 0:18c9492be42e 3
meurigp 0:18c9492be42e 4 #include "mbed.h"
meurigp 0:18c9492be42e 5
meurigp 0:18c9492be42e 6 // change this to alter tolerance of joystick direction
meurigp 0:18c9492be42e 7 #define DIRECTION_TOLERANCE 0.05
meurigp 0:18c9492be42e 8
meurigp 0:18c9492be42e 9 // connections for joystick
meurigp 2:e444008676a4 10 InterruptIn button(PTB11);
meurigp 0:18c9492be42e 11 AnalogIn xPot(PTB2);
meurigp 0:18c9492be42e 12 AnalogIn yPot(PTB3);
meurigp 0:18c9492be42e 13
meurigp 3:ae04f59e274a 14 Ticker pollJoystick;
meurigp 3:ae04f59e274a 15
meurigp 0:18c9492be42e 16 // create enumerated type (0,1,2,3 etc. for direction)
meurigp 0:18c9492be42e 17 // could be extended for diagonals etc.
meurigp 0:18c9492be42e 18 enum DirectionName {
meurigp 0:18c9492be42e 19 UP,
meurigp 0:18c9492be42e 20 DOWN,
meurigp 0:18c9492be42e 21 LEFT,
meurigp 0:18c9492be42e 22 RIGHT,
meurigp 0:18c9492be42e 23 CENTRE,
meurigp 0:18c9492be42e 24 UNKNOWN
meurigp 0:18c9492be42e 25 };
meurigp 0:18c9492be42e 26
meurigp 0:18c9492be42e 27 // struct for Joystick
meurigp 0:18c9492be42e 28 typedef struct JoyStick Joystick;
meurigp 0:18c9492be42e 29 struct JoyStick {
meurigp 0:18c9492be42e 30 float x; // current x value
meurigp 0:18c9492be42e 31 float x0; // 'centred' x value
meurigp 0:18c9492be42e 32 float y; // current y value
meurigp 0:18c9492be42e 33 float y0; // 'centred' y value
meurigp 0:18c9492be42e 34 int button; // button state (assume pull-down used, so 1 = pressed, 0 = unpressed)
meurigp 0:18c9492be42e 35 DirectionName direction; // current direction
meurigp 0:18c9492be42e 36 };
meurigp 0:18c9492be42e 37 // create struct variable
meurigp 0:18c9492be42e 38 Joystick joystick;
meurigp 0:18c9492be42e 39
meurigp 0:18c9492be42e 40 int printFlag = 0;
meurigp 2:e444008676a4 41 volatile int buttonFlag = 0;
meurigp 2:e444008676a4 42
meurigp 2:e444008676a4 43
meurigp 0:18c9492be42e 44
meurigp 0:18c9492be42e 45 // function prototypes
meurigp 2:e444008676a4 46 void buttonISR();
meurigp 0:18c9492be42e 47 void calibrateJoystick();
meurigp 0:18c9492be42e 48 void updateJoystick();
meurigp 0:18c9492be42e 49
meurigp 2:e444008676a4 50 void buttonISR()
meurigp 2:e444008676a4 51 {
meurigp 2:e444008676a4 52 buttonFlag = 1;
meurigp 2:e444008676a4 53 }
meurigp 0:18c9492be42e 54
meurigp 0:18c9492be42e 55 // read default positions of the joystick to calibrate later readings
meurigp 0:18c9492be42e 56 void calibrateJoystick()
meurigp 0:18c9492be42e 57 {
meurigp 0:18c9492be42e 58 button.mode(PullDown);
meurigp 0:18c9492be42e 59 // must not move during calibration
meurigp 0:18c9492be42e 60 joystick.x0 = xPot; // initial positions in the range 0.0 to 1.0 (0.5 if centred exactly)
meurigp 0:18c9492be42e 61 joystick.y0 = yPot;
meurigp 0:18c9492be42e 62 }
meurigp 0:18c9492be42e 63 void updateJoystick()
meurigp 0:18c9492be42e 64 {
meurigp 0:18c9492be42e 65 // read current joystick values relative to calibrated values (in range -0.5 to 0.5, 0.0 is centred)
meurigp 0:18c9492be42e 66 joystick.x = xPot - joystick.x0;
meurigp 0:18c9492be42e 67 joystick.y = yPot - joystick.y0;
meurigp 0:18c9492be42e 68 // read button state
meurigp 0:18c9492be42e 69 joystick.button = button;
meurigp 0:18c9492be42e 70
meurigp 0:18c9492be42e 71 // calculate direction depending on x,y values
meurigp 0:18c9492be42e 72 // tolerance allows a little lee-way in case joystick not exactly in the stated direction
meurigp 0:18c9492be42e 73 if ( fabs(joystick.y) < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
meurigp 0:18c9492be42e 74 joystick.direction = CENTRE;
meurigp 0:18c9492be42e 75 } else if ( joystick.y > DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
meurigp 0:18c9492be42e 76 joystick.direction = UP;
meurigp 0:18c9492be42e 77 } else if ( joystick.y < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
meurigp 0:18c9492be42e 78 joystick.direction = DOWN;
meurigp 0:18c9492be42e 79 } else if ( joystick.x > DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
meurigp 0:18c9492be42e 80 joystick.direction = LEFT;
meurigp 0:18c9492be42e 81 } else if ( joystick.x < DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
meurigp 0:18c9492be42e 82 joystick.direction = RIGHT;
meurigp 0:18c9492be42e 83 } else {
meurigp 0:18c9492be42e 84 joystick.direction = UNKNOWN;
meurigp 0:18c9492be42e 85 }
meurigp 0:18c9492be42e 86
meurigp 0:18c9492be42e 87 // set flag for printing
meurigp 0:18c9492be42e 88 printFlag = 1;
meurigp 0:18c9492be42e 89 }
meurigp 0:18c9492be42e 90
meurigp 0:18c9492be42e 91 #endif