mirror of https://github.com/ArduPilot/ardupilot
96 lines
2.9 KiB
C++
96 lines
2.9 KiB
C++
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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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APM_Baro.cpp - barometer driver
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public License
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as published by the Free Software Foundation; either version 2.1
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of the License, or (at your option) any later version.
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*/
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#include <FastSerial.h>
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#include <AP_Common.h>
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#include <AP_Baro.h>
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// calibrate the barometer. This must be called at least once before
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// the altitude() or climb_rate() interfaces can be used
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void AP_Baro::calibrate(void (*callback)(unsigned long t))
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{
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int32_t ground_pressure = 0;
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int16_t ground_temperature;
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while (ground_pressure == 0 || !healthy) {
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read(); // Get initial data from absolute pressure sensor
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ground_pressure = get_pressure();
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ground_temperature = get_temperature();
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callback(20);
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}
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for (int i = 0; i < 30; i++) {
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do {
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read();
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} while (!healthy);
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ground_pressure = (ground_pressure * 9l + get_pressure()) / 10l;
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ground_temperature = (ground_temperature * 9 + get_temperature()) / 10;
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callback(20);
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}
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_ground_pressure.set_and_save(ground_pressure);
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_ground_temperature.set_and_save(ground_temperature / 10.0f);
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}
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// return current altitude estimate relative to time that calibrate()
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// was called. Returns altitude in meters
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// note that this relies on read() being called regularly to get new data
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float AP_Baro::get_altitude(void)
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{
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float scaling, temp;
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if (_last_altitude_t == _last_update) {
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// no new information
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return _altitude;
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}
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// this has no filtering of the pressure values, use a separate
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// filter if you want a smoothed value. The AHRS driver wants
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// unsmoothed values
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scaling = (float)_ground_pressure / (float)get_pressure();
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temp = ((float)_ground_temperature) + 273.15f;
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_altitude = log(scaling) * temp * 29.271267f;
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_last_altitude_t = _last_update;
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return _altitude;
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}
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// return current climb_rate estimeate relative to time that calibrate()
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// was called. Returns climb rate in meters/s, positive means up
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// note that this relies on read() being called regularly to get new data
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float AP_Baro::get_climb_rate(void)
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{
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float alt, deltat;
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if (_last_climb_rate_t == _last_update) {
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// no new information
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return _climb_rate;
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}
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if (_last_climb_rate_t == 0) {
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// first call
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_last_altitude = get_altitude();
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_last_climb_rate_t = _last_update;
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_climb_rate = 0.0;
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return _climb_rate;
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}
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deltat = (_last_update - _last_climb_rate_t) * 1.0e-3;
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alt = get_altitude();
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// we use a 5 point average filter on the climb rate. This seems
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// to produce somewhat reasonable results on real hardware
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_climb_rate = _climb_rate_filter.apply((alt - _last_altitude) / deltat);
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_last_altitude = alt;
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_last_climb_rate_t = _last_update;
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return _climb_rate;
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}
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