00001 /* mbed USB Slingshot, 
00002  *
00003  * Copyright (c) 2010-2011 mbed.org, MIT License
00004  * 
00005  * smokrani, sford
00006  *
00007  * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
00008  * and associated documentation files (the "Software"), to deal in the Software without
00009  * restriction, including without limitation the rights to use, copy, modify, merge, publish,
00010  * distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the
00011  * Software is furnished to do so, subject to the following conditions:
00012  * 
00013  *  The above copyright notice and this permission notice shall be included in all copies or
00014  * substantial portions of the Software.
00015  *
00016  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
00017  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00018  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
00019  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00020  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
00021  */
00022 
00023 #include "mbed.h"
00024 #include "USBMouse.h"
00025 #include "ADXL345.h"
00026 
00027 // Physical interfaces
00028 USBMouse mouse;
00029 ADXL345 accelerometer(p5, p6, p7, p8);
00030 AnalogIn stretch_sensor(p15);
00031 BusOut leds(LED1, LED2, LED3, LED4);
00032 
00033 // Return slingshot angle in radians, up > 0 > down
00034 float get_angle() {
00035     int readings[3];
00036     accelerometer.getOutput(readings);
00037     float x = (int16_t)readings[0];
00038     float z = (int16_t)readings[2];
00039     return atan(z / x);    
00040 }
00041 
00042 // Return normalised stretch value based on bounds of all readings seen
00043 float get_stretch() {
00044     static float min_strength = 0.7;
00045     static float max_strength = 0.7;
00046     float current_strength = stretch_sensor.read();
00047     if(current_strength > max_strength) { max_strength = current_strength; }
00048     if(current_strength < min_strength) { min_strength = current_strength; }
00049     float stretch = (current_strength - min_strength) / (max_strength - min_strength);
00050     return 1.0 - stretch;
00051 }
00052 
00053 // move mouse to a location relative to the start point, stepping as needed
00054 void move_mouse(int x, int y) {
00055     const int STEP = 10;
00056     static int current_x = 0;
00057     static int current_y = 0;
00058     
00059     int move_x = x - current_x;
00060     int move_y = y - current_y; 
00061 
00062     // Move the mouse, in steps of max step size to ensure it is picked up by OS
00063     while(move_x > STEP) { mouse.move(STEP, 0); move_x -= STEP; }
00064     while(move_x < -STEP) { mouse.move(-STEP, 0); move_x += STEP; }
00065     while(move_y > STEP) { mouse.move(0, STEP); move_y -= STEP; }
00066     while(move_y < -STEP) { mouse.move(0, -STEP); move_y += STEP; }
00067     mouse.move(move_x, move_y);
00068     
00069     current_x = x;
00070     current_y = y;
00071 }
00072 
00073 template <class T>
00074 T filter(T* array, int len, T value) {
00075     T mean = 0.0;
00076     for(int i = 0; i<len - 1; i++) {
00077         mean += array[i + 1];
00078         array[i] = array[i + 1];
00079     }
00080     mean += value;
00081     array[len - 1] = value;
00082     return mean / (T)len;
00083 }
00084 
00085 typedef enum {
00086     WAITING = 2,
00087     AIMING = 4,
00088     FIRING = 8
00089 } state_t;
00090 
00091 int main() {
00092     leds = 1;
00093 
00094     // setup accelerometer
00095     accelerometer.setPowerControl(0x00);
00096     accelerometer.setDataFormatControl(0x0B);
00097     accelerometer.setDataRate(ADXL345_3200HZ);
00098     accelerometer.setPowerControl(0x08);
00099 
00100     state_t state = WAITING;    
00101     Timer timer;
00102 
00103     float angles[8] = {0};
00104     float stretches[8] = {0};
00105     
00106     while(1) {        
00107 
00108         // get the slingshot parameters
00109         float this_stretch = get_stretch();
00110         float this_angle = get_angle();
00111 
00112         // apply some filtering
00113         float stretch = filter(stretches, 8, this_stretch);
00114         float angle = filter(angles, 8, this_angle);
00115             
00116         leds = state;
00117                 
00118         // act based on the current state
00119         switch (state) {
00120             case WAITING:
00121                 if(stretch > 0.5) {             // significant stretch, considered starting 
00122                     mouse.press(MOUSE_LEFT);
00123                     state = AIMING;
00124                 }
00125                 break;
00126 
00127             case AIMING:
00128                 if(stretch - this_stretch > 0.1) { // rapid de-stretch, considered a fire
00129                     mouse.release(MOUSE_LEFT);
00130                     move_mouse(0, 0);
00131                     timer.start();
00132                     state = FIRING;
00133                 } else {
00134                     int x = 0.0 - cos(angle) * stretch * 200;
00135                     int y = sin(angle) * stretch * 200;
00136                     move_mouse(x, y);
00137                 }
00138                 break;
00139 
00140             case FIRING:
00141                 if(timer > 3.0) {
00142                     timer.stop();
00143                     timer.reset();
00144                     state = WAITING;
00145                 }        
00146                 break;
00147         };
00148         
00149         wait(0.01);
00150     }
00151 }