ardupilot/libraries/AP_Baro/AP_Baro.h

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-

#ifndef __AP_BARO_H__
#define __AP_BARO_H__

#include <AP_Param.h>
#include <Filter.h>
#include <DerivativeFilter.h>

class AP_Baro
{
public:
    AP_Baro() :
        _last_update(0),
        _pressure_samples(0),
        _altitude(0.0f),
        _last_altitude_EAS2TAS(0.0f),
        _EAS2TAS(0.0f),
        _last_altitude_t(0),
        _last_external_temperature_ms(0)
    {
        // initialise flags
        _flags.healthy = false;
        _flags.alt_ok = false;

		AP_Param::setup_object_defaults(this, var_info);
    }

    // healthy - returns true if sensor and derived altitude are good
    bool healthy() const { return _flags.healthy && _flags.alt_ok; }

    virtual bool            init()=0;
    virtual uint8_t         read() = 0;

    // pressure in Pascal. Divide by 100 for millibars or hectopascals
    virtual float           get_pressure() = 0;

    // temperature in degrees C
    virtual float           get_temperature() const = 0;

    // accumulate a reading - overridden in some drivers
    virtual void            accumulate(void) {}

    // calibrate the barometer. This must be called on startup if the
    // altitude/climb_rate/acceleration interfaces are ever used
    // the callback is a delay() like routine
    void        calibrate();

    // update the barometer calibration to the current pressure. Can
    // be used for incremental preflight update of baro
    void        update_calibration();

    // get current altitude in meters relative to altitude at the time
    // of the last calibrate() call
    float        get_altitude(void);

    // get altitude difference in meters relative given a base
    // pressure in Pascal
    float get_altitude_difference(float base_pressure, float pressure) const;

    // get scale factor required to convert equivalent to true airspeed
    float        get_EAS2TAS(void);

    // return how many pressure samples were used to obtain
    // the last pressure reading
    uint8_t        get_pressure_samples(void) {
        return _pressure_samples;
    }

    // get current climb rate in meters/s. A positive number means
    // going up
    float           get_climb_rate(void);

    // ground temperature in degrees C
    // the ground values are only valid after calibration
    float           get_ground_temperature(void) {
        return _ground_temperature.get();
    }

    // ground pressure in Pascal
    // the ground values are only valid after calibration
    float           get_ground_pressure(void) {
        return _ground_pressure.get();
    }

    // set the temperature to be used for altitude calibration. This
    // allows an external temperature source (such as a digital
    // airspeed sensor) to be used as the temperature source
    void set_external_temperature(float temperature);

    // get last time sample was taken (in ms)
    uint32_t        get_last_update() const { return _last_update; };

    static const struct AP_Param::GroupInfo        var_info[];

protected:

    struct Baro_flags {
        uint8_t healthy :1;             // true if sensor is healthy
        uint8_t alt_ok  :1;             // true if calculated altitude is ok
    } _flags;

    uint32_t                            _last_update; // in ms
    uint8_t                             _pressure_samples;

private:
    // get the temperature to be used for altitude calibration
    float                               get_calibration_temperature(void) const;


    AP_Float                            _ground_temperature;
    AP_Float                            _ground_pressure;
    AP_Int8                             _alt_offset;
    float                               _altitude;
    float                               _last_altitude_EAS2TAS;
    float                               _EAS2TAS;
    float                               _external_temperature;
    uint32_t                            _last_external_temperature_ms;
    uint32_t                            _last_altitude_t;
    DerivativeFilterFloat_Size7         _climb_rate_filter;
};

#include "AP_Baro_MS5611.h"
#include "AP_Baro_BMP085.h"
#include "AP_Baro_HIL.h"
#include "AP_Baro_PX4.h"
#include "AP_Baro_VRBRAIN.h"

#endif // __AP_BARO_H__