ardupilot/libraries/AP_Airspeed/AP_Airspeed_analog.cpp

60 lines
1.6 KiB
C++

/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
* analog airspeed driver
*/
#include <AP_HAL.h>
#include <AP_Math.h>
#include <AP_Common.h>
#include <AP_ADC.h>
#include <AP_ADC_AnalogSource.h>
#include <AP_Airspeed.h>
extern const AP_HAL::HAL& hal;
// scaling for 3DR analog airspeed sensor
#define VOLTS_TO_PASCAL 819
#if CONFIG_HAL_BOARD == HAL_BOARD_APM1
extern AP_ADC_ADS7844 apm1_adc;
#endif
bool AP_Airspeed_Analog::init()
{
#if CONFIG_HAL_BOARD == HAL_BOARD_APM1
if (_pin == 64) {
_source = new AP_ADC_AnalogSource( &apm1_adc, 7, 1.0f);
return true;
}
#endif
_source = hal.analogin->channel(_pin);
return true;
}
// read the airspeed sensor
bool AP_Airspeed_Analog::get_differential_pressure(float &pressure)
{
if (_source == NULL) {
return false;
}
_source->set_pin(_pin);
pressure = _source->voltage_average_ratiometric() * VOLTS_TO_PASCAL;
return true;
}