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/**
 * @section LICENSE
 *
 * Copyright (c) 2010 ARM Limited
 *
 * 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.
 *
 * @section DESCRIPTION
 *
 * IMU consisting of ADXL345 accelerometer and ITG-3200 gyroscope using
 * orientation filter developed by Sebastian Madgwick.
 *
 * Find more details about his paper here:
 *
 * http://code.google.com/p/imumargalgorithm30042010sohm/
 */

#ifndef MBED_IMU_H
#define MBED_IMU_H

/**
 * Includes
 */
#include "mbed.h"
#include "ADXL345.h"
#include "ITG3200.h"
#include "IMUfilter.h"

/**
 * Defines
 */
#define IMU_RATE           0.025
#define ACCELEROMETER_RATE 0.005
#define GYROSCOPE_RATE     0.005
#define GYRO_MEAS_ERROR    0.3 //IMUfilter tuning parameter.

//Gravity at Earth's surface in m/s/s
#define g0 9.812865328
//Number of samples to average
#define SAMPLES 4
#define CALIBRATION_SAMPLES 128
//Multiply radians to get degrees.
#define toDegrees(x) (x * 57.2957795)
//Multiply degrees to get radians.
#define toRadians(x) (x * 0.01745329252)
//Full scale resolution on the ADXL345 is 4mg/LSB.
//Multiply ADC count readings from ADXL345 to get acceleration in m/s/s.
#define toAcceleration(x) (x * (4 * g0 * 0.001))
//14.375 LSB/(degrees/sec)
#define GYROSCOPE_GAIN (1 / 14.375)
#define ACCELEROMETER_GAIN (0.004 * g0)

/**
 * IMU consisting of ADXL345 accelerometer and ITG-3200 gyroscope to calculate
 * roll, pitch and yaw angles.
 */
class IMU {

public:

    /**
     * Constructor.
     *
     * @param imuRate Rate which IMUfilter update and Euler angle calculation
     *                occurs.
     * @param gyroscopeMeasurementError IMUfilter tuning parameter.
     * @param accelerometerRate Rate at which accelerometer data is sampled.
     * @param gyroscopeRate Rate at which gyroscope data is sampled.
     */
    IMU(float imuRate,
        double gyroscopeMeasurementError,
        float accelerometerRate,
        float gyroscopeRate);

    /**
     * Get the current roll angle.
     *
     * @return The current roll angle in degrees.
     */
    double getRoll(void);

    /**
     * Get the current pitch angle.
     *
     * @return The current pitch angle in degrees.
     */
    double getPitch(void);

    /**
     * Get the current yaw angle.
     *
     * @return The current yaw angle in degrees.
     */
    double getYaw(void);

    /**
     * Sample the sensors, and if enough samples have been taken,
     * take an average, and compute the new Euler angles.
     */
    void sample(void);
    
    /**
     * Recalibrate the sensors and reset the IMU filter.
     */
    void reset(void);

private:

    /**
     * Set up the ADXL345 appropriately.
     */
    void initializeAccelerometer(void);

    /**
     * Calculate the zero g offset.
     */
    void calibrateAccelerometer(void);

    /**
     * Take a set of samples and average them.
     */
    void sampleAccelerometer(void);

    /**
     * Set up the ITG-3200 appropriately.
     */
    void initializeGyroscope(void);

    /**
     * Calculate the bias offset.
     */
    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);

    ADXL345   accelerometer;
    ITG3200   gyroscope;
    IMUfilter imuFilter;

    Ticker accelerometerTicker;
    Ticker gyroscopeTicker;
    Ticker sampleTicker;
    Ticker filterTicker;

    float accelerometerRate_;
    float gyroscopeRate_;
    float imuRate_;

    //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;

    double a_xBias;
    double a_yBias;
    double a_zBias;

    volatile double a_xAccumulator;
    volatile double a_yAccumulator;
    volatile double a_zAccumulator;
    volatile double w_xAccumulator;
    volatile double w_yAccumulator;
    volatile double w_zAccumulator;

    //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];
    int accelerometerSamples;
    int gyroscopeSamples;

};

#endif /* MBED_IMU_H */