LibrePilot/flight/modules/Airspeed/baro_airspeed_mpxv.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_MPXV)

#define CALIBRATION_IDLE_MS                   2000   // Time to wait before calibrating, in [ms]
#define CALIBRATION_COUNT_MS                  2000   // Time to spend calibrating, in [ms]
#define ANALOG_BARO_AIRSPEED_TIME_CONSTANT_MS 100 // low pass filter

// Private types

// Private variables

// Private functions

static uint16_t calibrationCount = 0;

PIOS_MPXV_descriptor sensor = { .type = PIOS_MPXV_UNKNOWN };


void baro_airspeedGetMPXV(AirspeedSensorData *airspeedSensor, AirspeedSettingsData *airspeedSettings, int8_t airspeedADCPin)
{
    // Ensure that the ADC pin is properly configured
    if (airspeedADCPin < 0) {
        airspeedSensor->SensorConnected = AIRSPEEDSENSOR_SENSORCONNECTED_FALSE;
        AlarmsSet(SYSTEMALARMS_ALARM_AIRSPEED, SYSTEMALARMS_ALARM_ERROR);
        return;
    }
    if (sensor.type == PIOS_MPXV_UNKNOWN) {
        switch (airspeedSettings->AirspeedSensorType) {
        case AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV7002:
            sensor = PIOS_MPXV_7002_DESC(airspeedADCPin);
            break;
        case AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV5004:
            sensor = PIOS_MPXV_5004_DESC(airspeedADCPin);
            break;
        default:
            airspeedSensor->SensorConnected = AIRSPEEDSENSOR_SENSORCONNECTED_FALSE;
            AlarmsSet(SYSTEMALARMS_ALARM_AIRSPEED, SYSTEMALARMS_ALARM_ERROR);
            return;
        }
    }

    airspeedSensor->SensorValue = PIOS_MPXV_Measure(&sensor);

    if (!airspeedSettings->ZeroPoint) {
        AlarmsSet(SYSTEMALARMS_ALARM_AIRSPEED, SYSTEMALARMS_ALARM_WARNING);
        // Calibrate sensor by averaging zero point value
        if (calibrationCount < CALIBRATION_IDLE_MS / airspeedSettings->SamplePeriod) { // First let sensor warm up and stabilize.
            calibrationCount++;
            return;
        } else if (calibrationCount <= (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) { // Then compute the average.
            calibrationCount++; /*DO NOT MOVE FROM BEFORE sensorCalibration=... LINE, OR ELSE WILL HAVE DIVIDE BY ZERO */

            PIOS_MPXV_Calibrate(&sensor, airspeedSensor->SensorValue);

            // Set settings UAVO. The airspeed UAVO is set elsewhere in the function.
            if (calibrationCount > (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) {
                airspeedSettings->ZeroPoint = sensor.zeroPoint;
                AirspeedSettingsZeroPointSet(&airspeedSettings->ZeroPoint);
            }
            return;
        }
    }
    sensor.zeroPoint = airspeedSettings->ZeroPoint;

    // Filter CAS
    float alpha = airspeedSettings->SamplePeriod / (airspeedSettings->SamplePeriod + ANALOG_BARO_AIRSPEED_TIME_CONSTANT_MS); // Low pass filter.

    airspeedSensor->CalibratedAirspeed = PIOS_MPXV_CalcAirspeed(&sensor, airspeedSensor->SensorValue) * (alpha) + airspeedSensor->CalibratedAirspeed * (1.0f - alpha);
    airspeedSensor->SensorConnected    = AIRSPEEDSENSOR_SENSORCONNECTED_TRUE;
    AlarmsSet(SYSTEMALARMS_ALARM_AIRSPEED, SYSTEMALARMS_ALARM_OK);
}

#endif /* if defined(PIOS_INCLUDE_MPXV) */

/**
 * @}
 * @}
 */