flight/modules/Airspeed/baro_airspeed_mpxv.c

   1 /**
   2  ******************************************************************************
   3  * @addtogroup OpenPilotModules OpenPilot Modules
   4  * @{
   5  * @addtogroup AirspeedModule Airspeed Module
   6  * @brief Communicate with airspeed sensors and return values
   7  * @{
   8  *
   9  * @file       baro_airspeed.c
  10  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
  11  * @brief      Airspeed module, handles temperature and pressure readings from BMP085
  12  *
  13  * @see        The GNU Public License (GPL) Version 3
  14  *
  15  *****************************************************************************/
  16 /*
  17  * This program is free software; you can redistribute it and/or modify
  18  * it under the terms of the GNU General Public License as published by
  19  * the Free Software Foundation; either version 3 of the License, or
  20  * (at your option) any later version.
  21  *
  22  * This program is distributed in the hope that it will be useful, but
  23  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  24  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  25  * for more details.
  26  *
  27  * You should have received a copy of the GNU General Public License along
  28  * with this program; if not, write to the Free Software Foundation, Inc.,
  29  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  30  */
  31
  32 /**
  33  * Output object: BaroAirspeed
  34  *
  35  * This module will periodically update the value of the BaroAirspeed object.
  36  *
  37  */
  38
  39 #include "openpilot.h"
  40 #include "hwsettings.h"
  41 #include "airspeedsettings.h"
  42 #include "airspeedsensor.h" // object that will be updated by the module
  43 #include "airspeedalarm.h"
  44
  45 #if defined(PIOS_INCLUDE_MPXV)
  46
  47 #define CALIBRATION_IDLE_MS                   2000   // Time to wait before calibrating, in [ms]
  48 #define CALIBRATION_COUNT_MS                  2000   // Time to spend calibrating, in [ms]
  49 #define ANALOG_BARO_AIRSPEED_TIME_CONSTANT_MS 256 // low pass filter
  50
  51 // Private types
  52
  53 // Private variables
  54
  55 // Private functions
  56
  57 static uint16_t calibrationCount = 0;
  58
  59 PIOS_MPXV_descriptor sensor = { .type = PIOS_MPXV_UNKNOWN };
  60
  61
  62 void baro_airspeedGetMPXV(AirspeedSensorData *airspeedSensor, AirspeedSettingsData *airspeedSettings, int8_t airspeedADCPin)
  63 {
  64     // Ensure that the ADC pin is properly configured
  65     if (airspeedADCPin < 0) {
  66         airspeedSensor->SensorConnected = AIRSPEEDSENSOR_SENSORCONNECTED_FALSE;
  67         AirspeedAlarm(SYSTEMALARMS_ALARM_ERROR);
  68         return;
  69     }
  70     if (sensor.type == PIOS_MPXV_UNKNOWN) {
  71         switch (airspeedSettings->AirspeedSensorType) {
  72         case AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV7002:
  73             sensor = PIOS_MPXV_7002_DESC(airspeedADCPin);
  74             break;
  75         case AIRSPEEDSETTINGS_AIRSPEEDSENSORTYPE_DIYDRONESMPXV5004:
  76             sensor = PIOS_MPXV_5004_DESC(airspeedADCPin);
  77             break;
  78         default:
  79             airspeedSensor->SensorConnected = AIRSPEEDSENSOR_SENSORCONNECTED_FALSE;
  80             AirspeedAlarm(SYSTEMALARMS_ALARM_ERROR);
  81             return;
  82         }
  83     }
  84
  85     airspeedSensor->SensorValue = PIOS_MPXV_Measure(&sensor);
  86
  87     if (!airspeedSettings->ZeroPoint) {
  88         AirspeedAlarm(SYSTEMALARMS_ALARM_WARNING);
  89         // Calibrate sensor by averaging zero point value
  90         if (calibrationCount < CALIBRATION_IDLE_MS / airspeedSettings->SamplePeriod) { // First let sensor warm up and stabilize.
  91             calibrationCount++;
  92             return;
  93         } else if (calibrationCount <= (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) { // Then compute the average.
  94             calibrationCount++; /*DO NOT MOVE FROM BEFORE sensorCalibration=... LINE, OR ELSE WILL HAVE DIVIDE BY ZERO */
  95
  96             PIOS_MPXV_Calibrate(&sensor, airspeedSensor->SensorValue);
  97
  98             // Set settings UAVO. The airspeed UAVO is set elsewhere in the function.
  99             if (calibrationCount > (CALIBRATION_IDLE_MS + CALIBRATION_COUNT_MS) / airspeedSettings->SamplePeriod) {
 100                 airspeedSettings->ZeroPoint = sensor.zeroPoint;
 101                 AirspeedSettingsZeroPointSet(&airspeedSettings->ZeroPoint);
 102             }
 103             return;
 104         }
 105     }
 106     sensor.zeroPoint = airspeedSettings->ZeroPoint;
 107     sensor.scale     = airspeedSettings->Scale;
 108
 109     // Filter CAS : airspeedSettings->SamplePeriod value is 0 - 255 range
 110     float alpha = 1 - (airspeedSettings->SamplePeriod / ANALOG_BARO_AIRSPEED_TIME_CONSTANT_MS); // Low pass filter.
 111
 112     airspeedSensor->CalibratedAirspeed = PIOS_MPXV_CalcAirspeed(&sensor, airspeedSensor->SensorValue) * (alpha) + airspeedSensor->CalibratedAirspeed * (1.0f - alpha);
 113     airspeedSensor->SensorConnected    = AIRSPEEDSENSOR_SENSORCONNECTED_TRUE;
 114     AirspeedAlarm(SYSTEMALARMS_ALARM_OK);
 115 }
 116
 117 #endif /* if defined(PIOS_INCLUDE_MPXV) */
 118
 119 /**
 120  * @}
 121  * @}
 122  */