How to Use MBED as a mouse to Play AngryBirdz

How to Use MBED as a mouse

.from: http://mbed.org/cookbook/Slingshot

Check this in action!

So now you can kill pigs with a real USB Slingshot, by combining the two totally different worlds of carpentry and embedded systems!

XXXXXXXXXXXXXXXXXXXXXXXX main.cpp XXXXXXXXXXXXXXXXXXXXXXXXXXX

/* mbed USB Slingshot, 
 *
 * Copyright (c) 2010-2011 mbed.org, MIT License
 * 
 * smokrani, sford
 *
 * 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 "mbed.h"
#include "USBMouse.h"
#include "ADXL345.h"

// Physical interfaces
USBMouse mouse;
ADXL345 accelerometer(p5, p6, p7, p8);
AnalogIn stretch_sensor(p15);
BusOut leds(LED1, LED2, LED3, LED4);

// Return slingshot angle in radians, up > 0 > down
float get_angle() {
    int readings[3];
    accelerometer.getOutput(readings);
    float x = (int16_t)readings[0];
    float z = (int16_t)readings[2];
    return atan(z / x);    
}

// Return normalised stretch value based on bounds of all readings seen
float get_stretch() {
    static float min_strength = 0.7;
    static float max_strength = 0.7;
    float current_strength = stretch_sensor.read();
    if(current_strength > max_strength) { max_strength = current_strength; }
    if(current_strength < min_strength) { min_strength = current_strength; }
    float stretch = (current_strength - min_strength) / (max_strength - min_strength);
    return 1.0 - stretch;
}

// move mouse to a location relative to the start point, stepping as needed
void move_mouse(int x, int y) {
    const int STEP = 10;
    static int current_x = 0;
    static int current_y = 0;
    
    int move_x = x - current_x;
    int move_y = y - current_y; 

    // Move the mouse, in steps of max step size to ensure it is picked up by OS
    while(move_x > STEP) { mouse.move(STEP, 0); move_x -= STEP; }
    while(move_x < -STEP) { mouse.move(-STEP, 0); move_x += STEP; }
    while(move_y > STEP) { mouse.move(0, STEP); move_y -= STEP; }
    while(move_y < -STEP) { mouse.move(0, -STEP); move_y += STEP; }
    mouse.move(move_x, move_y);
    
    current_x = x;
    current_y = y;
}

template <class T>
T filter(T* array, int len, T value) {
    T mean = 0.0;
    for(int i = 0; i<len - 1; i++) {
        mean += array[i + 1];
        array[i] = array[i + 1];
    }
    mean += value;
    array[len - 1] = value;
    return mean / (T)len;
}

typedef enum {
    WAITING = 2,
    AIMING = 4,
    FIRING = 8
} state_t;

int main() {
    leds = 1;

    // setup accelerometer
    accelerometer.setPowerControl(0x00);
    accelerometer.setDataFormatControl(0x0B);
    accelerometer.setDataRate(ADXL345_3200HZ);
    accelerometer.setPowerControl(0x08);

    state_t state = WAITING;    
    Timer timer;

    float angles[8] = {0};
    float stretches[8] = {0};
    
    while(1) {        

        // get the slingshot parameters
        float this_stretch = get_stretch();
        float this_angle = get_angle();

        // apply some filtering
        float stretch = filter(stretches, 8, this_stretch);
        float angle = filter(angles, 8, this_angle);
            
        leds = state;
                
        // act based on the current state
        switch (state) {
            case WAITING:
                if(stretch > 0.5) {             // significant stretch, considered starting 
                    mouse.press(MOUSE_LEFT);
                    state = AIMING;
                }
                break;

            case AIMING:
                if(stretch - this_stretch > 0.1) { // rapid de-stretch, considered a fire
                    mouse.release(MOUSE_LEFT);
                    move_mouse(0, 0);
                    timer.start();
                    state = FIRING;
                } else {
                    int x = 0.0 - cos(angle) * stretch * 200;
                    int y = sin(angle) * stretch * 200;
                    move_mouse(x, y);
                }
                break;

            case FIRING:
                if(timer > 3.0) {
                    timer.stop();
                    timer.reset();
                    state = WAITING;
                }        
                break;
        };
        
        wait(0.01);
    }
}

XXXXXXXXXXXXXXXXXXXXXXXX test.cpp XXXXXXXXXXXXXXXXXXXXXXXXXXX

#include "mbed.h"
#include "USBMouse.h"
#include "ADXL345.h"
 
USBMouse mouse;
ADXL345 acc(p5, p6, p7, p8);
AnalogIn strength(p15);
 
int main() {
    //Initialize accelerometer
    acc.setPowerControl(0x00);
    acc.setDataFormatControl(0x0B);
    acc.setDataRate(ADXL345_3200HZ);
    acc.setPowerControl(0x08);
 
    while (1) {
        int readings[3];
        acc.getOutput(readings);        // test accelerometer
        printf("acc: %i, %i, %i\r\n", (int16_t)readings[0], (int16_t)readings[1], (int16_t)readings[2]);
 
        uint16_t str = strength.read_u16();        // test stretch sensor
        printf("strength: %d\r\n", str);
       
        mouse.move(10, 10);             // test USB relative mouse

        wait(0.1);
    }
}

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Here is the pinout table:

ADXL345 Signal Name	mbed pin
Vcc	Vout
Gnd	Gnd
SDA	p5
SDO	p6
SCL	p7
CS	p8
Stretch sensor	mbed pin
One extremity	Vout
The other	p15
USB connector	mbed pin
Vcc	Vin
Gnd	Gnd
D+	D+
D-	D-