File content as of revision 2:044740372a78:

/**
 * IMU filter example.
 *
 * Calculate the roll, pitch and yaw angles.
 */
#include "IMUfilter.h"
#include "ADXL345_I2C.h"
#include "ITG3200.h"
#include "USBMouse.h"


#define MOVERATE 1
#define MAXMOVE 100
#define MOVETHRESHOLD 3
//Gravity at Earth's surface in m/s/s
#define g0 9.812865328
//Number of samples to average.
#define SAMPLES 2
//Number of samples to be averaged for a null bias calculation
//during calibration.
#define CALIBRATION_SAMPLES 32
//Convert from radians to degrees.
#define toDegrees(x) (x * 57.2957795)
//Convert from degrees to radians.
#define toRadians(x) (x * 0.01745329252)
//ITG-3200 sensitivity is 14.375 LSB/(degrees/sec).
#define GYROSCOPE_GAIN (1 / 14.375)
//Full scale resolution on the ADXL345 is 4mg/LSB.
#define ACCELEROMETER_GAIN (0.000061035 * g0)
//Sampling gyroscope at .
#define GYRO_RATE   0.005
//Sampling accelerometer at 
#define ACC_RATE    0.005
#define FILTER_RATE 0.015

DigitalIn leftClick(p16);
DigitalIn rightClick(p15);

Serial pc(USBTX, USBRX);
//At rest the gyroscope is centred around 0 and goes between about
//-5 and 5 counts. As 1 degrees/sec is ~15 LSB, error is roughly
//5/15 = 0.3 degrees/sec.
IMUfilter imuFilter(FILTER_RATE, 0.3);
ADXL345_I2C accelerometer(p28, p27);
ITG3200 gyroscope(p28, p27);
USBMouse mouse;

Ticker accelerometerTicker;
Ticker gyroscopeTicker;
Ticker filterTicker;

/**
 * IMU filter example.
 *
 * Calculate the roll, pitch and yaw angles.
 */
 


//Offsets for the gyroscope.
//The readings we take when the gyroscope is stationary won't be 0, so we'll
//average a set of readings we do get when the gyroscope is stationary and
//take those away from subsequent readings to ensure the gyroscope is offset
//or "biased" to 0.
double w_xBias;
double w_yBias;
double w_zBias;

//Offsets for the accelerometer.
//Same as with the gyroscope.
double a_xBias;
double a_yBias;
double a_zBias;

//Accumulators used for oversampling and then averaging.
volatile double a_xAccumulator = 0;
volatile double a_yAccumulator = 0;
volatile double a_zAccumulator = 0;
volatile double w_xAccumulator = 0;
volatile double w_yAccumulator = 0;
volatile double w_zAccumulator = 0;

//Accelerometer and gyroscope readings for x, y, z axes.
volatile double a_x;
volatile double a_y;
volatile double a_z;
volatile double w_x;
volatile double w_y;
volatile double w_z;

//Buffer for accelerometer readings.
int readings[3];
//Number of accelerometer samples we're on.
int accelerometerSamples = 0;
//Number of gyroscope samples we're on.
int gyroscopeSamples = 0;

/**
 * Prototypes
 */
//Set up the ADXL345 appropriately.
void initializeAcceleromter(void);
//Calculate the null bias.
void calibrateAccelerometer(void);
//Take a set of samples and average them.
void sampleAccelerometer(void);
//Set up the ITG3200 appropriately.
void initializeGyroscope(void);
//Calculate the null bias.
void calibrateGyroscope(void);
//Take a set of samples and average them.
void sampleGyroscope(void);
//Update the filter and calculate the Euler angles.
void filter(void);
void processMove(void);
void processClick(void);

void initializeAccelerometer(void) {

    //Go into standby mode to configure the device.
    accelerometer.setPowerControl(0x00);
    //Full resolution, +/-16g, 4mg/LSB.
    accelerometer.setDataFormatControl(0x0B);
    //200Hz data rate.
    accelerometer.setDataRate(ADXL345_1600HZ);
    //Measurement mode.
    accelerometer.setPowerControl(0x08);
    //See http://www.analog.com/static/imported-files/application_notes/AN-1077.pdf
    wait_ms(22);

}

void initializeGyroscope(void) {

    //Low pass filter bandwidth of 42Hz.
    gyroscope.setLpBandwidth(LPFBW_42HZ);
    gyroscope.setSampleRateDivider(0);
    pc.printf("%d\n", gyroscope.getSampleRateDivider());
    pc.printf("%d\n", gyroscope.getInternalSampleRate());
    wait_ms(22);
}


void calibrateAccelerometer(void) {
    
    pc.printf("Calibrating Accelerometer\n");
    a_xAccumulator = 0;
    a_yAccumulator = 0;
    a_zAccumulator = 0;
    
    //Take a number of readings and average them
    //to calculate the zero g offset.
    for (int i = 0; i < CALIBRATION_SAMPLES; i++) {
    
    accelerometer.getOutput(readings);
    a_xAccumulator += (int16_t) readings[0];
    a_yAccumulator += (int16_t) readings[1];
    a_zAccumulator += (int16_t) readings[2];


    wait(ACC_RATE);

    }

    a_xAccumulator /= CALIBRATION_SAMPLES;
    a_yAccumulator /= CALIBRATION_SAMPLES;
    a_zAccumulator /= CALIBRATION_SAMPLES;

    //At 4mg/LSB, 250 LSBs is 1g.
    a_xBias = a_xAccumulator;
    a_yBias = a_yAccumulator;
    a_zBias = (a_zAccumulator - 981);

    a_xAccumulator = 0;
    a_yAccumulator = 0;
    a_zAccumulator = 0;
    pc.printf("Calibration Complete\n");
}



void calibrateGyroscope(void) {
    
    pc.printf("Calibrating Gyro\n");
    w_xAccumulator = 0;
    w_yAccumulator = 0;
    w_zAccumulator = 0;

    //Take a number of readings and average them
    //to calculate the gyroscope bias offset.
    for (int i = 0; i < CALIBRATION_SAMPLES; i++) {

        w_xAccumulator += gyroscope.getGyroX();
        w_yAccumulator += gyroscope.getGyroY();
        w_zAccumulator += gyroscope.getGyroZ();
        wait(GYRO_RATE);
    }

    //Average the samples.
    w_xAccumulator /= CALIBRATION_SAMPLES;
    w_yAccumulator /= CALIBRATION_SAMPLES;
    w_zAccumulator /= CALIBRATION_SAMPLES;

    w_xBias = w_xAccumulator;
    w_yBias = w_yAccumulator;
    w_zBias = w_zAccumulator;

    w_xAccumulator = 0;
    w_yAccumulator = 0;
    w_zAccumulator = 0;
    
    pc.printf("Calibration Complete\n");
}


void sampleAccelerometer(void) {

    //Have we taken enough samples?
    if (accelerometerSamples == SAMPLES) {

        //Average the samples, remove the bias, and calculate the acceleration
        //in m/s/s.
        a_x = ((a_xAccumulator / SAMPLES) - a_xBias) * ACCELEROMETER_GAIN;
        a_y = ((a_yAccumulator / SAMPLES) - a_yBias) * ACCELEROMETER_GAIN;
        a_z = ((a_zAccumulator / SAMPLES) - a_zBias) * ACCELEROMETER_GAIN;

        a_xAccumulator = 0;
        a_yAccumulator = 0;
        a_zAccumulator = 0;
        accelerometerSamples = 0;

    } else {
        //Take another sample.
        accelerometer.getOutput(readings);
        a_xAccumulator += (int16_t) readings[0];
        a_yAccumulator += (int16_t) readings[1];
        a_zAccumulator += (int16_t) readings[2];

        accelerometerSamples++;
        //pc.printf("Sample Accl %d", accelerometerSamples);
    }

}


void sampleGyroscope(void) {

    //Have we taken enough samples?
    if (gyroscopeSamples == SAMPLES) {

        //Average the samples, remove the bias, and calculate the angular
        //velocity in rad/s.
        w_x = toRadians(((w_xAccumulator / SAMPLES) - w_xBias) * GYROSCOPE_GAIN);
        w_y = toRadians(((w_yAccumulator / SAMPLES) - w_yBias) * GYROSCOPE_GAIN);
        w_z = toRadians(((w_zAccumulator / SAMPLES) - w_zBias) * GYROSCOPE_GAIN);

        w_xAccumulator = 0;
        w_yAccumulator = 0;
        w_zAccumulator = 0;
        gyroscopeSamples = 0;

    } else {
        //Take another sample.
        w_xAccumulator += gyroscope.getGyroX();
        w_yAccumulator += gyroscope.getGyroY();
        w_zAccumulator += gyroscope.getGyroZ();

        gyroscopeSamples++;
        //pc.printf("Sample Gyro %d", gyroscopeSamples);
    }

}

void filter(void) {
    //Update the filter variables.
    imuFilter.updateFilter(w_y, w_x, w_z, a_y, a_x, a_z);
    //Calculate the new Euler angles.
    imuFilter.computeEuler();

}

void processClick()
{
     static bool preRightClick = false;  

     if (leftClick == 0)   
     {  
        mouse.press(MOUSE_LEFT);
     }  
     else
     {  
        mouse.release(MOUSE_LEFT);          
     }

     // Right Mouse Click  ___  Falling Edge Detection
     if (rightClick == 0 && preRightClick == false)
     {  
         preRightClick = true;
     } 
     else if (rightClick == 1 && preRightClick == true)
     {   preRightClick = false;
         mouse.click(MOUSE_RIGHT);      
     }  
}


void processMove(void)
{    
    int16_t move_x, move_y;
        
        
    move_x = (int16_t)(-MOVERATE*toDegrees(imuFilter.getRoll()));
    move_y = (int16_t)(-MOVERATE*toDegrees(imuFilter.getPitch()));      

    if (move_x <= MOVETHRESHOLD && move_x >= -MOVETHRESHOLD)
         move_x = 0;
    else if (move_x > MOVETHRESHOLD){
         if (move_x > MAXMOVE+MOVETHRESHOLD) move_x = MAXMOVE;
          else move_x -=MOVETHRESHOLD;
     }
            
    else{
         if (move_x < -MAXMOVE-MOVETHRESHOLD) move_x = -MAXMOVE;    
           else move_x+=MOVETHRESHOLD;
    } 
            
        
        if (move_y <= MOVETHRESHOLD && move_y  >= -MOVETHRESHOLD)
            move_y = 0;
        else if (move_y > MOVETHRESHOLD){
            if (move_y > MAXMOVE+MOVETHRESHOLD) move_y = MAXMOVE;
            else move_y -=MOVETHRESHOLD;
        }
            
        else{
            if (move_y < -MAXMOVE-MOVETHRESHOLD) move_y = -MAXMOVE;    
            else move_y+=MOVETHRESHOLD;
        } 
                   
        pc.printf("move_x = %d,  move_ y = %d\n", move_x,move_y);  
                
        mouse.move(move_x, move_y);            
   }

int main() {

    //pc.printf("Starting IMU filter test...\n");

    //Initialize inertial sensors.
    initializeAccelerometer();
    calibrateAccelerometer();
    initializeGyroscope();
    calibrateGyroscope();

   
    
    leftClick.mode(PullUp); 
    rightClick.mode(PullUp); 
    //pc.printf("Initialized Successfully...\n\r");

    //Set up timers.
    //Accelerometer data rate is 200Hz, so we'll sample at this speed.
    accelerometerTicker.attach(&sampleAccelerometer, GYRO_RATE);
    //Gyroscope data rate is 200Hz, so we'll sample at this speed.
    gyroscopeTicker.attach(&sampleGyroscope, ACC_RATE);
    //Update the filter variables at the correct rate.
    filterTicker.attach(&filter, FILTER_RATE);
   
   
   //pc.printf("Timers Setup...Entering Loop...\n\r");
     
   
    while (1) {

        wait(0.01);
        pc.printf("angle_x = %f,  angle_ y = %f\n",-toDegrees(imuFilter.getRoll()),-toDegrees(imuFilter.getPitch()));   
        processClick();
        processMove();
    }

}