Richard Wunderlich / Joystick

Handles reading and scaling the analog inputs from a simple 2-axis joystick with a pushbutton. Can also attach rise and fall interrupts to the button.

Dependents:   joystickdeneme NOKIA_KOMBAT projekat

Purpose

Simple library for reading an analog joystick like those found on game console controllers. These joysticks usually also have a pushbutton.

Example

Joystick Library Example

// Joystick Library Example
//
// Reads the joystick x axis and fades green and red LEDs in response.
// The blue LED is turned on while the pushbutton is pressed.

#include "mbed.h"
#include <Joystick.h>

// target is the KL25Z
#define PIN_JOYX PTB0    // A0
#define PIN_JOYY PTB1    // A1
#define PIN_JOYA PTB2

PwmOut led_R(LED1);
PwmOut led_G(LED2);
PwmOut led_B(LED3);

Joystick j(PIN_JOYX, PIN_JOYY, PIN_JOYA);

// call on joystick button release
void jrise(void) {
    led_B = 1.0f;
}

// call on joystick button press
void jfall(void) {
    led_B = 0.0f;
}

int main () {
    // setup
    led_R = 1.0f;
    led_G = 1.0f;
    led_B = 1.0f;
    joypos p;    // joystick position
    // attach joystick button interrupts
    j.rise(&jrise);
    j.fall(&jfall);
    float fade = 0.0f;

    // loop
    while (1) {
        p = j.read();
        fade = p.x;
        if (fade > 0.0) {
            led_R = 1.0f;
            led_G = 1.0f - (float)fade;
        } else if (fade < 0.0) {
            led_R = 1.0f + (float)fade;
            led_G = 1.0f;
        } else {
            led_R = 1.0f;
            led_G = 1.0f;
        }
        wait(0.01);
    }
}

Files at this revision

API Documentation at this revision

Revision 0:13d10cc6a822, committed 2015-08-05

Comitter:
rwunderl
Date:
Wed Aug 05 20:21:34 2015 +0000
Commit message:
Initial commit of the Joystick library.

Changed in this revision

Joystick.cpp Show annotated file Show diff for this revision Revisions of this file
Joystick.h Show annotated file Show diff for this revision Revisions of this file 
diff -r 000000000000 -r 13d10cc6a822 Joystick.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Joystick.cpp	Wed Aug 05 20:21:34 2015 +0000
@@ -0,0 +1,104 @@
+/* mbed Joystick Library
+ * Copyright (c) 2015, rwunderl, http://mbed.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "Joystick.h"
+
+// apply the deadzone to the axis extremes (comment if you don't want to use this feature)
+#define JOYSTICK_DEADZONE_EXTREMES
+
+// adjust the deadzone value for your application, if required
+const double JOYSTICK_DEADZONE = 0.01;
+// set up these constants so they don't have to be calculated every time
+#ifdef JOYSTICK_DEADZONE_EXTREMES
+    const double JOYSTICK_MIN    = 0.0 + JOYSTICK_DEADZONE;    // effective minimum joystick value
+    const double JOYSTICK_MINMID = 0.5 - JOYSTICK_DEADZONE;    // minimum-side midpoint value
+    const double JOYSTICK_MAXMID = 0.5 + JOYSTICK_DEADZONE;    // maximum-side midpoint value
+    const double JOYSTICK_MAX    = 1.0 - JOYSTICK_DEADZONE;    // effective maximum joystick value
+#else
+    const double JOYSTICK_MIN    = 0.0;    // minimum joystick value
+    const double JOYSTICK_MINMID = 0.5 - JOYSTICK_DEADZONE;    // minimum-side midpoint value
+    const double JOYSTICK_MAXMID = 0.5 + JOYSTICK_DEADZONE;    // maximum-side midpoint value
+    const double JOYSTICK_MAX    = 1.0;    // maximum joystick value
+#endif
+
+double _map(double value, double in_min, double in_max, double out_min, double out_max) {
+    return (value - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
+}
+
+double _scale(double pos) {
+    double scaled = 0;
+
+    if (pos < JOYSTICK_MINMID) {
+        scaled = _map(pos, JOYSTICK_MIN, JOYSTICK_MINMID, -1, 0);
+    } else if (pos > JOYSTICK_MAXMID) {
+        scaled = _map(pos, JOYSTICK_MAXMID, JOYSTICK_MAX, 0, 1);
+    }
+
+    // check out of bounds [-1.0, 1.0] (happens at the extremes)
+    if (scaled < -1) {
+        scaled = -1;
+    } else if (scaled > 1) {
+        scaled = 1;
+    }
+
+    return scaled;
+}
+
+Joystick::Joystick(PinName x, PinName y, PinName a) : _x(x), _y(y), _a(a) {
+}
+
+joypos Joystick::read() {
+    joypos pos;
+
+    pos.x = getX();
+    pos.y = getY();
+
+    return pos;
+}
+
+double Joystick::getX() {
+    double val = _x.read();
+    val = _scale(val);
+    return val;
+}
+
+double Joystick::getY() {
+    double val = _y.read();
+    val = _scale(val);
+    return val;
+}
+
+double Joystick::getRawX() {
+    return _x.read();
+}
+
+double Joystick::getRawY() {
+    return _y.read();
+}
+
+void Joystick::rise(void (*fptr)(void)) { 
+    _a.rise(fptr);
+}
+
+void Joystick::fall(void (*fptr)(void)) {
+    _a.fall(fptr);
+}

diff -r 000000000000 -r 13d10cc6a822 Joystick.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Joystick.h	Wed Aug 05 20:21:34 2015 +0000
@@ -0,0 +1,112 @@
+/* mbed Joystick Library
+ * Copyright (c) 2015, rwunderl, http://mbed.org
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#ifndef MBED_JOYSTICK_H
+#define MBED_JOYSTICK_H
+
+#include "mbed.h"
+
+/** Joystick position structure
+ *
+ * Struct to keep track of the joystick x and y positions.
+ */
+struct joypos {
+    double x;
+    double y;
+};
+
+/** Joystick class
+ *
+ * Reads a 2-axis analog joystick and keeps track of its positions.
+ *
+ * The joystick uses 2 AnalogIns and 1 DigitalIn
+ *     - X AnalogIn
+ *     - Y AnalogIn
+ *     - A DigitalIn (momentary pushbutton; Low is pressed)
+ */
+class Joystick {
+public:
+    /** Joystick interface
+     * Create the joystick object and assign pins.
+     *
+     * @param x X-axis AnalogIn.
+     * @param y Y-axis AnalogIn.
+     * @param a Pushbutton DigitalIn.
+     */ 
+    Joystick(PinName x, PinName y, PinName a);
+
+    /** Read the joystick position
+     * The position is returned as a joypos value with x and y in the range [-1.0, 1.0].
+     *
+     * @returns Position structure of the joystick.
+     */
+    joypos read();
+
+    /** Get the X position
+     * Read the joystick's horizontal position, represented as a double value in the range [-1.0, 1.0].
+     *
+     * @returns Horizontal position of the joystick.
+     */
+    double getX();
+
+    /** Get the Y position
+     * Read the joystick's vertical position, represented as a double value in the range [-1.0, 1.0].
+     *
+     * @returns Vertical position of the joystick.
+     */
+    double getY();
+
+    /** Get the raw X position
+     * Read the joystick's raw horizontal position, represented as a double value in the range [0.0, 1.0].
+     *
+     * @returns Horizontal position of the joystick.
+     */
+    double getRawX();
+
+    /** Get the raw Y position
+     * Read the joystick's raw vertical position, represented as a double value in the range [0.0, 1.0].
+     *
+     * @returns Vertical position of the joystick.
+     */
+    double getRawY();
+
+    /** Attach the rise interrupt
+     * Attach a function pointer to call when a rising edge occurs on the button input.
+     *
+     * @param fptr Pointer to a void function. Set to NULL or 0 for none.
+     */
+    void rise(void (*fptr)(void));
+
+    /** Attach the fall interrupt
+     * Attach a function pointer to call when a falling edge occurs on the button input.
+     *
+     * @param fptr Pointer to a void function. Set to NULL or 0 for none.
+     */
+    void fall(void (*fptr)(void));
+
+protected:
+    AnalogIn _x;
+    AnalogIn _y;
+    InterruptIn _a;
+};
+
+#endif /* MBED_JOYSTICK_H */