precisionAccelerometer.h

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/*
 * Copyright (c) 2015, Freescale Semiconductor, Inc.
 * Copyright 2016-2017 NXP
 * All rights reserved.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

/*! \file precisionAccelerometer.h
    \brief Implements accelerometer calibration routines
*/

#ifndef PRECISIONACCELEROMETER_H
#define PRECISIONACCELEROMETER_H

/// calibration constants
#define ACCEL_CAL_AVERAGING_SECS                2                               ///< calibration measurement averaging period (s)
#define MAX_ACCEL_CAL_ORIENTATIONS              12                              ///< number of stored precision accelerometer measurements

/// accelerometer measurement buffer
typedef struct AccelBuffer
{
                float fGsStored[MAX_ACCEL_CAL_ORIENTATIONS][3]; ///< uncalibrated accelerometer measurements (g)
                float fSumGs[3];                                                                ///< averaging sum for current storage location
                int16_t iStoreCounter;                                                          ///< number of remaining iterations at FUSION_HZ to average measurement
                int16_t iStoreLocation;                                                         ///< -1 for none, 0 to 11 for the 12 storage locations
                int16_t iStoreFlags;                                                            ///< denotes which measurements are present
} AccelBuffer;

/// precision accelerometer calibration structure
typedef struct AccelCalibration
{
                // start of elements stored in flash memory
                float fV[3];                                                                    ///< offset vector (g)
                float finvW[3][3];                                                              ///< inverse gain matrix
                float fR0[3][3];                                                                ///< forward rotation matrix for measurement 0
                // end of elements stored in flash memory
                float fmatA[10][10];                                                    ///< scratch 10x10 matrix used by calibration algorithms
                float fmatB[10][10];                                                    ///< scratch 10x10 matrix used by calibration algorithms
                float fvecA[10];                                                                ///< scratch 10x1 vector used by calibration algorithms
                float fvecB[4];                                                                 ///< scratch 4x1 vector used by calibration algorithms
                float fA[3][3];                                                                 ///< ellipsoid matrix A
                float finvA[3][3];                                                              ///< inverse of the ellipsoid matrix A
} AccelCalibration;

struct AccelSensor;  // actual typedef is located in sensor_fusion_types.h

// function prototypes for functions in precisionAcclerometer.c
/// Initialize the accelerometer calibration functions
void fInitializeAccelCalibration(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    volatile int8_t *AccelCalPacketOn                   ///< Used to coordinate calibration sample storage and communications
);
/// Update the buffer used to store samples used for accelerometer calibration.
void fUpdateAccelBuffer(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelSensor* pthisAccel,                     ///< Pointer to the accelerometer input/state structure
    volatile int8_t *AccelCalPacketOn                   ///< Used to coordinate calibration sample storage and communications
);
/// function maps the accelerometer data fGs (g) onto precision calibrated and de-rotated data fGc (g), iGc (counts)
void fInvertAccelCal(
    struct AccelSensor *pthisAccel,                     ///< Pointer to the accelerometer input/state structure
    struct AccelCalibration *pthisAccelCal              ///< Accelerometer calibration parameter structure
);
/// function runs the precision accelerometer calibration
void fRunAccelCalibration(
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 4 element calibration from the available measurements
void fComputeAccelCalibration4(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 7 element calibration from the available measurements
void fComputeAccelCalibration7(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);
/// calculate the 10 element calibration from the available measurements
void fComputeAccelCalibration10(
    struct AccelBuffer *pthisAccelBuffer,               ///< Buffer of measurements used as input to the accel calibration functions
    struct AccelCalibration *pthisAccelCal,             ///< Accelerometer calibration parameter structure
    struct AccelSensor* pthisAccel                      ///< Pointer to the accelerometer input/state structure
);

#endif // PRECISIONACCELEROMETER_H