ardupilot/libraries/AP_Baro/AP_Baro.h

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#pragma once
#include <AP_HAL/AP_HAL.h>
#include <AP_Param/AP_Param.h>
#include <Filter/Filter.h>
#include <Filter/DerivativeFilter.h>
// maximum number of sensor instances
#define BARO_MAX_INSTANCES 3
// maximum number of drivers. Note that a single driver can provide
// multiple sensor instances
#define BARO_MAX_DRIVERS 3
// timeouts for health reporting
#define BARO_TIMEOUT_MS 500 // timeout in ms since last successful read
#define BARO_DATA_CHANGE_TIMEOUT_MS 2000 // timeout in ms since last successful read that involved temperature of pressure changing
class AP_Baro_Backend;
class AP_Baro
{
friend class AP_Baro_Backend;
friend class AP_Baro_SITL; // for access to sensors[]
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public:
// constructor
AP_Baro();
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// barometer types
typedef enum {
BARO_TYPE_AIR,
BARO_TYPE_WATER
} baro_type_t;
// initialise the barometer object, loading backend drivers
void init(void);
// update the barometer object, asking backends to push data to
// the frontend
void update(void);
// healthy - returns true if sensor and derived altitude are good
bool healthy(void) const { return healthy(_primary); }
bool healthy(uint8_t instance) const { return sensors[instance].healthy && sensors[instance].alt_ok && sensors[instance].calibrated; }
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// check if all baros are healthy - used for SYS_STATUS report
bool all_healthy(void) const;
// pressure in Pascal. Divide by 100 for millibars or hectopascals
float get_pressure(void) const { return get_pressure(_primary); }
float get_pressure(uint8_t instance) const { return sensors[instance].pressure; }
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// temperature in degrees C
float get_temperature(void) const { return get_temperature(_primary); }
float get_temperature(uint8_t instance) const { return sensors[instance].temperature; }
// accumulate a reading on sensors. Some backends without their
// own thread or a timer may need this.
void accumulate(void);
// calibrate the barometer. This must be called on startup if the
// altitude/climb_rate/acceleration interfaces are ever used
void calibrate(bool save=true);
// update the barometer calibration to the current pressure. Can
// be used for incremental preflight update of baro
void update_calibration(void);
// get current altitude in meters relative to altitude at the time
// of the last calibrate() call
float get_altitude(void) const { return get_altitude(_primary); }
float get_altitude(uint8_t instance) const { return sensors[instance].altitude; }
// 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);
// get air density / sea level density - decreases as altitude climbs
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float get_air_density_ratio(void);
// 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) const;
// ground pressure in Pascal
// the ground values are only valid after calibration
float get_ground_pressure(void) const { return get_ground_pressure(_primary); }
float get_ground_pressure(uint8_t i) const { return sensors[i].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);
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// get last time sample was taken (in ms)
uint32_t get_last_update(void) const { return get_last_update(_primary); }
uint32_t get_last_update(uint8_t instance) const { return sensors[instance].last_update_ms; }
// settable parameters
static const struct AP_Param::GroupInfo var_info[];
float get_external_temperature(void) const { return get_external_temperature(_primary); };
float get_external_temperature(const uint8_t instance) const;
// HIL (and SITL) interface, setting altitude
void setHIL(float altitude_msl);
// HIL (and SITL) interface, setting pressure, temperature, altitude and climb_rate
// used by Replay
void setHIL(uint8_t instance, float pressure, float temperature, float altitude, float climb_rate, uint32_t last_update_ms);
// Set the primary baro
void set_primary_baro(uint8_t primary) { _primary_baro.set_and_save(primary); };
// Set the type (Air or Water) of a particular instance
void set_type(uint8_t instance, baro_type_t type) { sensors[instance].type = type; };
// Get the type (Air or Water) of a particular instance
baro_type_t get_type(uint8_t instance) { return sensors[instance].type; };
// HIL variables
struct {
float pressure;
float temperature;
float altitude;
float climb_rate;
uint32_t last_update_ms;
bool updated:1;
bool have_alt:1;
bool have_last_update:1;
} _hil;
// register a new sensor, claiming a sensor slot. If we are out of
// slots it will panic
uint8_t register_sensor(void);
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// return number of registered sensors
uint8_t num_instances(void) const { return _num_sensors; }
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// enable HIL mode
void set_hil_mode(void) { _hil_mode = true; }
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// set baro drift amount
void set_baro_drift_altitude(float alt) { _alt_offset = alt; }
// get baro drift amount
float get_baro_drift_offset(void) { return _alt_offset_active; }
// simple atmospheric model
static void SimpleAtmosphere(const float alt, float &sigma, float &delta, float &theta);
// set a pressure correction from AP_TempCalibration
void set_pressure_correction(uint8_t instance, float p_correction);
private:
// how many drivers do we have?
uint8_t _num_drivers;
AP_Baro_Backend *drivers[BARO_MAX_DRIVERS];
// how many sensors do we have?
uint8_t _num_sensors;
// what is the primary sensor at the moment?
uint8_t _primary;
struct sensor {
baro_type_t type; // 0 for air pressure (default), 1 for water pressure
uint32_t last_update_ms; // last update time in ms
uint32_t last_change_ms; // last update time in ms that included a change in reading from previous readings
bool healthy:1; // true if sensor is healthy
bool alt_ok:1; // true if calculated altitude is ok
bool calibrated:1; // true if calculated calibrated successfully
float pressure; // pressure in Pascal
float temperature; // temperature in degrees C
float altitude; // calculated altitude
AP_Float ground_pressure;
float p_correction;
} sensors[BARO_MAX_INSTANCES];
AP_Float _alt_offset;
float _alt_offset_active;
AP_Int8 _primary_baro; // primary chosen by user
AP_Int8 _ext_bus; // bus number for external barometer
float _last_altitude_EAS2TAS;
float _EAS2TAS;
float _external_temperature;
uint32_t _last_external_temperature_ms;
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DerivativeFilterFloat_Size7 _climb_rate_filter;
AP_Float _specific_gravity; // the specific gravity of fluid for an ROV 1.00 for freshwater, 1.024 for salt water
AP_Float _user_ground_temperature; // user override of the ground temperature used for EAS2TAS
bool _hil_mode:1;
float _guessed_ground_temperature; // currently ground temperature estimate using our best abailable source
// when did we last notify the GCS of new pressure reference?
uint32_t _last_notify_ms;
bool _add_backend(AP_Baro_Backend *backend);
};