ardupilot/libraries/AP_Baro/AP_Baro.cpp

134 lines
4.7 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
* APM_Baro.cpp - barometer driver
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1
* of the License, or (at your option) any later version.
*/
#include <AP_Math.h>
#include <AP_Common.h>
#include <AP_Baro.h>
#include <AP_HAL.h>
extern const AP_HAL::HAL& hal;
// table of user settable parameters
const AP_Param::GroupInfo AP_Baro::var_info[] PROGMEM = {
// NOTE: Index numbers 0 and 1 were for the old integer
// ground temperature and pressure
// @Param: ABS_PRESS
// @DisplayName: Absolute Pressure
// @Description: calibrated ground pressure
// @Increment: 1
AP_GROUPINFO("ABS_PRESS", 2, AP_Baro, _ground_pressure, 0),
// @Param: ABS_PRESS
// @DisplayName: ground temperature
// @Description: calibrated ground temperature
// @Increment: 1
AP_GROUPINFO("TEMP", 3, AP_Baro, _ground_temperature, 0),
AP_GROUPEND
};
// calibrate the barometer. This must be called at least once before
// the altitude() or climb_rate() interfaces can be used
void AP_Baro::calibrate()
{
float ground_pressure = 0;
float ground_temperature = 0;
{
uint32_t tstart = hal.scheduler->millis();
while (ground_pressure == 0 || !healthy) {
read(); // Get initial data from absolute pressure sensor
if (hal.scheduler->millis() - tstart > 500) {
hal.scheduler->panic(PSTR("PANIC: AP_Baro::read unsuccessful "
"for more than 500ms in AP_Baro::calibrate [1]\r\n"));
}
ground_pressure = get_pressure();
ground_temperature = get_temperature();
hal.scheduler->delay(20);
}
}
// let the barometer settle for a full second after startup
// the MS5611 reads quite a long way off for the first second,
// leading to about 1m of error if we don't wait
for (uint8_t i = 0; i < 10; i++) {
uint32_t tstart = hal.scheduler->millis();
do {
read();
if (hal.scheduler->millis() - tstart > 500) {
hal.scheduler->panic(PSTR("PANIC: AP_Baro::read unsuccessful "
"for more than 500ms in AP_Baro::calibrate [2]\r\n"));
}
} while (!healthy);
ground_pressure = get_pressure();
ground_temperature = get_temperature();
hal.scheduler->delay(100);
}
// now average over 5 values for the ground pressure and
// temperature settings
for (uint16_t i = 0; i < 5; i++) {
uint32_t tstart = hal.scheduler->millis();
do {
read();
if (hal.scheduler->millis() - tstart > 500) {
hal.scheduler->panic(PSTR("PANIC: AP_Baro::read unsuccessful "
"for more than 500ms in AP_Baro::calibrate [3]\r\n"));
}
} while (!healthy);
ground_pressure = (ground_pressure * 0.8f) + (get_pressure() * 0.2f);
ground_temperature = (ground_temperature * 0.8f) +
(get_temperature() * 0.2f);
hal.scheduler->delay(100);
}
_ground_pressure.set_and_save(ground_pressure);
_ground_temperature.set_and_save(ground_temperature / 10.0f);
}
// return current altitude estimate relative to time that calibrate()
// was called. Returns altitude in meters
// note that this relies on read() being called regularly to get new data
float AP_Baro::get_altitude(void)
{
float scaling, temp;
if (_last_altitude_t == _last_update) {
// no new information
return _altitude;
}
// this has no filtering of the pressure values, use a separate
// filter if you want a smoothed value. The AHRS driver wants
// unsmoothed values
scaling = (float)_ground_pressure / (float)get_pressure();
temp = ((float)_ground_temperature) + 273.15f;
_altitude = logf(scaling) * temp * 29.271267f;
_last_altitude_t = _last_update;
// ensure the climb rate filter is updated
_climb_rate_filter.update(_altitude, _last_update);
return _altitude;
}
// return current climb_rate estimeate relative to time that calibrate()
// was called. Returns climb rate in meters/s, positive means up
// note that this relies on read() being called regularly to get new data
float AP_Baro::get_climb_rate(void)
{
// we use a 7 point derivative filter on the climb rate. This seems
// to produce somewhat reasonable results on real hardware
return _climb_rate_filter.slope() * 1.0e3f;
}