Diff: Joystick.h

Revision:

4:463abe5f5135

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Joystick.h	Thu May 05 09:18:01 2016 +0000
@@ -0,0 +1,92 @@
+/**
+@file Joystick.h
+@brief Header file containing functions prototypes, defines and global variables for constructing joystick.
+@brief Example code of how to read a joystick with slightly changed for the game
+@https://www.sparkfun.com/products/9032
+@author Craig A. Evans
+@date 7 March 2015
+*/
+
+#ifndef JOYSTICK_H
+#define JOYSTICK_H
+
+#define DIRECTION_TOLERANCE 0.25
+
+/**
+Joystick vertical direction
+@brief Analog input for joystick to send vertical directions data
+*/
+AnalogIn yPot(PTB2);
+/**
+Joystick horizontal direction
+@brief Analog input for joystick to send horizontal direction data
+*/
+AnalogIn xPot(PTB3);
+
+//! create enumerated type (0,1,2,3 etc. for direction)
+//! could be extended for diagonals etc.
+enum DirectionName {
+    UP,
+    DOWN,
+    LEFT,
+    RIGHT,
+    CENTRE,
+    UNKNOWN
+};
+//! struct for Joystick
+typedef struct JoyStick Joystick;
+struct JoyStick {
+    double x;    // current x value
+    double x0;   // 'centred' x value
+    double y;    // current y value
+    double y0;   // 'centred' y value
+    int button; // button state (assume pull-down used, so 1 = pressed, 0 = unpressed)
+    DirectionName direction;  // current direction
+};
+//! create struct variable
+Joystick joystick;
+/**
+Read default positions of the joystick to calibrate later readings
+*/
+void calibrateJoystick();
+/**
+Update the current position of joystick
+*/
+void updateJoystick();
+
+/////////////////////////////////////////////////
+/// Function Definitions
+/////////////////////////////////////////////////
+
+// read default positions of the joystick to calibrate later readings
+void calibrateJoystick()
+{
+    // must not move during calibration
+    joystick.x0 = xPot;  // initial positions in the range 0.0 to 1.0 (0.5 if centred exactly)
+    joystick.y0 = yPot;
+}
+
+void updateJoystick()
+{
+    // read current joystick values relative to calibrated values (in range -0.5 to 0.5, 0.0 is centred)
+    joystick.x = xPot - joystick.x0;
+    joystick.y = yPot - joystick.y0;
+
+    // calculate direction depending on x,y values
+    // tolerance allows a little lee-way in case joystick not exactly in the stated direction
+    if ( fabs(joystick.y) < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
+        joystick.direction = CENTRE;
+    } else if ( joystick.y < DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
+        joystick.direction = UP;
+    } else if ( joystick.y > DIRECTION_TOLERANCE && fabs(joystick.x) < DIRECTION_TOLERANCE) {
+        joystick.direction = DOWN;
+    } else if ( joystick.x < DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
+        joystick.direction = RIGHT;
+    } else if ( joystick.x > DIRECTION_TOLERANCE && fabs(joystick.y) < DIRECTION_TOLERANCE) {
+        joystick.direction = LEFT;
+    } else {
+        joystick.direction = UNKNOWN;
+    }
+}
+
+#endif
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