LibrePilot/flight/modules/Airspeed/baro_airspeed_etasv3.c

/**
 ******************************************************************************
 * @addtogroup OpenPilotModules OpenPilot Modules
 * @{
 * @addtogroup AirspeedModule Airspeed Module
 * @brief Communicate with airspeed sensors and return values
 * @{
 *
 * @file       baro_airspeed.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      Airspeed module, handles temperature and pressure readings from BMP085
 *
 * @see        The GNU Public License (GPL) Version 3
 *
 *****************************************************************************/
/*
 * 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, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

/**
 * Output object: BaroAirspeed
 *
 * This module will periodically update the value of the BaroAirspeed object.
 *
 */

#include "openpilot.h"
#include "hwsettings.h"
#include "airspeedsettings.h"
#include "airspeedsensor.h" // object that will be updated by the module

#if defined(PIOS_INCLUDE_ETASV3)

#define CALIBRATION_IDLE_MS  2000   // Time to wait before calibrating, in [ms]
#define CALIBRATION_COUNT_MS 2000 // Time to spend calibrating, in [ms]

// Private types

// Private variables

// Private functions

static uint16_t calibrationCount  = 0;
static uint16_t calibrationCount2 = 0;
static uint32_t calibrationSum    = 0;


void baro_airspeedGetETASV3(AirspeedSensorData *airspeedSensor, AirspeedSettingsData *airspeedSettings)
{
    // Check to see if airspeed sensor is returning airspeedSensor
    airspeedSensor->SensorValue = PIOS_ETASV3_ReadAirspeed();
    if (airspeedSensor->SensorValue == (uint16_t)-1) {
        airspeedSensor->SensorConnected    = AIRSPEEDSENSOR_SENSORCONNECTED_FALSE;
        airspeedSensor->CalibratedAirspeed = 0;
        return;
    }

    // only calibrate if no stored calibration is available
    if (!airspeedSettings->ZeroPoint) {
        // Calibrate sensor by averaging zero point value
        if (calibrationCount <= CALIBRATION_IDLE_MS / airspeedSettings->SamplePeriod) {
            calibrationCount++;
            calibrationSum    = 0;
            calibrationCount2 = 0;
            return;
        } else if (calibrationCount <= (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) {
            calibrationCount++;
            calibrationCount2++;
            calibrationSum += airspeedSensor->SensorValue;
            if (calibrationCount > (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) {
                airspeedSettings->ZeroPoint = (int16_t)(((float)calibrationSum) / calibrationCount2);
                AirspeedSettingsZeroPointSet(&airspeedSettings->ZeroPoint);
                calibrationCount  = 0;
                calibrationSum    = 0;
                calibrationCount2 = 0;
            }
            return;
        }
    }

    // Compute airspeed
    airspeedSensor->CalibratedAirspeed = airspeedSettings->Scale * sqrtf((float)abs(airspeedSensor->SensorValue - airspeedSettings->ZeroPoint));
    airspeedSensor->SensorConnected    = AIRSPEEDSENSOR_SENSORCONNECTED_TRUE;
}


#endif /* if defined(PIOS_INCLUDE_ETASV3) */

/**
 * @}
 * @}
 */