baro_airspeed_analog.c

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/*
 * 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/>
 */

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

#if defined(PIOS_INCLUDE_MPXV7002) || defined (PIOS_INCLUDE_MPXV5004) || defined (PIOS_INCLUDE_ADC)

#define SAMPLING_DELAY_MS_MPXV                  10     //Update at 100Hz
#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   100.0f //Needs to be settable in a UAVO

// Private types

// Private variables

// Private functions

static uint16_t calibrationCount=0;


void baro_airspeedGetAnalog(BaroAirspeedData *baroAirspeedData, uint32_t *lastSysTime, uint8_t airspeedSensorType, int8_t airspeedADCPin)
{
        //Wait until our turn
        PIOS_Thread_Sleep_Until(lastSysTime, SAMPLING_DELAY_MS_MPXV);

        //Ensure that the ADC pin is properly configured
        if(airspeedADCPin <0){ //It's not, so revert to former sensor type
                baroAirspeedData->BaroConnected = BAROAIRSPEED_BAROCONNECTED_FALSE;

                return;
        }

        //Calibrate sensor by averaging zero point value //THIS SHOULD NOT BE DONE IF THERE IS AN IN-AIR RESET. HOW TO DETECT THIS?
        if (calibrationCount < CALIBRATION_IDLE_MS/SAMPLING_DELAY_MS_MPXV) { //First let sensor warm up and stabilize.
                calibrationCount++;
                return;
        } else if (calibrationCount <= (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS)/SAMPLING_DELAY_MS_MPXV) { //Then compute the average.
                calibrationCount++; /*DO NOT MOVE FROM BEFORE sensorCalibration=... LINE, OR ELSE WILL HAVE DIVIDE BY ZERO */

                uint16_t sensorCalibration;
#if defined(PIOS_INCLUDE_MPXV7002) || defined (PIOS_INCLUDE_MPXV5004) 
                if(airspeedSensorType==AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV7002){
                sensorCalibration=PIOS_MPXV7002_Calibrate(airspeedADCPin, calibrationCount-CALIBRATION_IDLE_MS/SAMPLING_DELAY_MS_MPXV);
                PIOS_MPXV7002_UpdateCalibration(sensorCalibration); //This makes sense for the user if the initial calibration was not good and the user does not wish to reboot.
                }
                else if(airspeedSensorType==AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV5004){
                sensorCalibration=PIOS_MPXV5004_Calibrate(airspeedADCPin, calibrationCount-CALIBRATION_IDLE_MS/SAMPLING_DELAY_MS_MPXV);
                PIOS_MPXV5004_UpdateCalibration(sensorCalibration); //This makes sense for the user if the initial calibration was not good and the user does not wish to reboot.
                }
#endif


                baroAirspeedData->BaroConnected = BAROAIRSPEED_BAROCONNECTED_TRUE;

                //Set settings UAVO. The airspeed UAVO is set elsewhere in the function.
                if (calibrationCount == (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS)/SAMPLING_DELAY_MS_MPXV)
                AirspeedSettingsZeroPointSet(&sensorCalibration);

                return;
        }

        //Get CAS
        float calibratedAirspeed=0;
#if defined(PIOS_INCLUDE_MPXV7002) || defined (PIOS_INCLUDE_MPXV5004) 
        if(airspeedSensorType==AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV7002){
                calibratedAirspeed = PIOS_MPXV7002_ReadAirspeed(airspeedADCPin);
                if (calibratedAirspeed < 0) //This only occurs when there's a bad ADC reading.
                return;

                //Get sensor value, just for telemetry purposes.
                //This is a silly waste of resources, and should probably be removed at some point in the future.
                //At this time, PIOS_MPXV7002_Measure() should become a static function and be removed from the header file.
                //
                //Moreover, due to the way the ADC driver is currently written, this code will return 0 more often than
                //not. This is something that will have to change on the ADC side of things.
                baroAirspeedData->SensorValue=PIOS_MPXV7002_Measure(airspeedADCPin);

        }
        else if(airspeedSensorType==AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV5004){
                calibratedAirspeed = PIOS_MPXV5004_ReadAirspeed(airspeedADCPin);
                if (calibratedAirspeed < 0) //This only occurs when there's a bad ADC reading.
                return;

                //Get sensor value, just for telemetry purposes.
                //This is a silly waste of resources, and should probably be removed at some point in the future.
                //At this time, PIOS_MPXV7002_Measure() should become a static function and be removed from the header file.
                //
                //Moreover, due to the way the ADC driver is currently written, this code will return 0 more often than
                //not. This is something that will have to change on the ADC side of things.
                baroAirspeedData->SensorValue=PIOS_MPXV5004_Measure(airspeedADCPin);

#else
        if (false) {
#endif
        } else if (airspeedSensorType == AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_RAWANALOG) {
                // will return raw ADC reading in mV (typically in range [0, 3300])
                calibratedAirspeed = PIOS_ADC_GetChannelRaw(airspeedADCPin);
                baroAirspeedData->SensorValue = calibratedAirspeed;
        }
        //Filter CAS
        float alpha=SAMPLING_DELAY_MS_MPXV/(SAMPLING_DELAY_MS_MPXV + ANALOG_BARO_AIRSPEED_TIME_CONSTANT_MS); //Low pass filter.
        float filteredAirspeed = calibratedAirspeed*(alpha) + baroAirspeedData->CalibratedAirspeed*(1.0f-alpha);

        //Set two values, one for the UAVO airspeed sensor reading, and the other for the GPS corrected one
        baroAirspeedData->CalibratedAirspeed = filteredAirspeed;

}

#else

void baro_airspeedGetAnalog(BaroAirspeedData *baroAirspeedData, uint32_t *lastSysTime, uint8_t airspeedSensorType, int8_t airspeedADCPin)
{
        /* Do nothing when driver support not compiled. */
        PIOS_Thread_Sleep_Until(lastSysTime, 1000);
}
#endif