LibrePilot/flight/modules/GPS/GPS.c

/**
 ******************************************************************************
 * @addtogroup OpenPilotModules OpenPilot Modules
 * @{
 * @addtogroup GSPModule GPS Module
 * @brief Process GPS information
 * @{
 *
 * @file       GPS.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      GPS module, handles GPS and NMEA stream
 * @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
 */

// ****************

#include <openpilot.h>

#include "gpspositionsensor.h"
#include "homelocation.h"
#include "gpstime.h"
#include "gpssatellites.h"
#include "gpsvelocitysensor.h"
#include "gpssettings.h"
#include "taskinfo.h"
#include "hwsettings.h"

#include "WorldMagModel.h"
#include "CoordinateConversions.h"

#include "GPS.h"
#include "NMEA.h"
#include "UBX.h"


// ****************
// Private functions

static void gpsTask(void *parameters);
static void updateSettings();

#ifdef PIOS_GPS_SETS_HOMELOCATION
static void setHomeLocation(GPSPositionSensorData *gpsData);
static float GravityAccel(float latitude, float longitude, float altitude);
#endif

// ****************
// Private constants

#define GPS_TIMEOUT_MS           500


#ifdef PIOS_GPS_SETS_HOMELOCATION
// Unfortunately need a good size stack for the WMM calculation
        #define STACK_SIZE_BYTES 1024
#else
#if defined(PIOS_GPS_MINIMAL)
        #define STACK_SIZE_BYTES 500
#else
        #define STACK_SIZE_BYTES 650
#endif // PIOS_GPS_MINIMAL
#endif // PIOS_GPS_SETS_HOMELOCATION

#define TASK_PRIORITY            (tskIDLE_PRIORITY + 1)

// ****************
// Private variables

static uint32_t gpsPort;
static bool gpsEnabled = false;

static xTaskHandle gpsTaskHandle;

static char *gps_rx_buffer;

static uint32_t timeOfLastCommandMs;
static uint32_t timeOfLastUpdateMs;

#if defined(PIOS_INCLUDE_GPS_NMEA_PARSER) || defined(PIOS_INCLUDE_GPS_UBX_PARSER)
static struct GPS_RX_STATS gpsRxStats;
#endif

// ****************
/**
 * Initialise the gps module
 * \return -1 if initialisation failed
 * \return 0 on success
 */

int32_t GPSStart(void)
{
    if (gpsEnabled) {
        if (gpsPort) {
            // Start gps task
            xTaskCreate(gpsTask, (signed char *)"GPS", STACK_SIZE_BYTES / 4, NULL, TASK_PRIORITY, &gpsTaskHandle);
            PIOS_TASK_MONITOR_RegisterTask(TASKINFO_RUNNING_GPS, gpsTaskHandle);
            return 0;
        }
    }
    return -1;
}

/**
 * Initialise the gps module
 * \return -1 if initialisation failed
 * \return 0 on success
 */
int32_t GPSInitialize(void)
{
    gpsPort = PIOS_COM_GPS;
    uint8_t gpsProtocol;

#ifdef MODULE_GPS_BUILTIN
    gpsEnabled = true;
#else
    HwSettingsInitialize();
    HwSettingsOptionalModulesData optionalModules;

    HwSettingsOptionalModulesGet(&optionalModules);

    if (optionalModules.GPS == HWSETTINGS_OPTIONALMODULES_ENABLED) {
        gpsEnabled = true;
    } else {
        gpsEnabled = false;
    }
#endif

#if defined(REVOLUTION)
    // These objects MUST be initialized for Revolution
    // because the rest of the system expects to just
    // attach to their queues
    GPSPositionSensorInitialize();
    GPSVelocitySensorInitialize();
    GPSTimeInitialize();
    GPSSatellitesInitialize();
    HomeLocationInitialize();
    updateSettings();

#else
    if (gpsPort && gpsEnabled) {
        GPSPositionSensorInitialize();
        GPSVelocitySensorInitialize();
#if !defined(PIOS_GPS_MINIMAL)
        GPSTimeInitialize();
        GPSSatellitesInitialize();
#endif
#if defined(PIOS_GPS_SETS_HOMELOCATION)
        HomeLocationInitialize();
#endif
        updateSettings();
    }
#endif /* if defined(REVOLUTION) */

    if (gpsPort && gpsEnabled) {
        GPSSettingsInitialize();
        GPSSettingsDataProtocolGet(&gpsProtocol);
        switch (gpsProtocol) {
        case GPSSETTINGS_DATAPROTOCOL_NMEA:
            gps_rx_buffer = pvPortMalloc(NMEA_MAX_PACKET_LENGTH);
            break;
        case GPSSETTINGS_DATAPROTOCOL_UBX:
            gps_rx_buffer = pvPortMalloc(sizeof(struct UBXPacket));
            break;
        default:
            gps_rx_buffer = NULL;
        }
        PIOS_Assert(gps_rx_buffer);

        return 0;
    }

    return -1;
}

MODULE_INITCALL(GPSInitialize, GPSStart);

// ****************
/**
 * Main gps task. It does not return.
 */

static void gpsTask(__attribute__((unused)) void *parameters)
{
    portTickType xDelay = 100 / portTICK_RATE_MS;
    uint32_t timeNowMs  = xTaskGetTickCount() * portTICK_RATE_MS;

    GPSPositionSensorData gpspositionsensor;
    GPSSettingsData gpsSettings;

    GPSSettingsGet(&gpsSettings);

    timeOfLastUpdateMs  = timeNowMs;
    timeOfLastCommandMs = timeNowMs;

    GPSPositionSensorGet(&gpspositionsensor);
    // Loop forever
    while (1) {
        uint8_t c;

        // This blocks the task until there is something on the buffer
        while (PIOS_COM_ReceiveBuffer(gpsPort, &c, 1, xDelay) > 0) {
            int res;
            switch (gpsSettings.DataProtocol) {
#if defined(PIOS_INCLUDE_GPS_NMEA_PARSER)
            case GPSSETTINGS_DATAPROTOCOL_NMEA:
                res = parse_nmea_stream(c, gps_rx_buffer, &gpspositionsensor, &gpsRxStats);
                break;
#endif
#if defined(PIOS_INCLUDE_GPS_UBX_PARSER)
            case GPSSETTINGS_DATAPROTOCOL_UBX:
                res = parse_ubx_stream(c, gps_rx_buffer, &gpspositionsensor, &gpsRxStats);
                break;
#endif
            default:
                res = NO_PARSER; // this should not happen
                break;
            }

            if (res == PARSER_COMPLETE) {
                timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;
                timeOfLastUpdateMs = timeNowMs;
                timeOfLastCommandMs = timeNowMs;
            }
        }

        // Check for GPS timeout
        timeNowMs = xTaskGetTickCount() * portTICK_RATE_MS;
        if ((timeNowMs - timeOfLastUpdateMs) >= GPS_TIMEOUT_MS) {
            // we have not received any valid GPS sentences for a while.
            // either the GPS is not plugged in or a hardware problem or the GPS has locked up.
            uint8_t status = GPSPOSITIONSENSOR_STATUS_NOGPS;
            GPSPositionSensorStatusSet(&status);
            AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_ERROR);
        } else {
            // we appear to be receiving GPS sentences OK, we've had an update
            // criteria for GPS-OK taken from this post...
            // http://forums.openpilot.org/topic/1523-professors-insgps-in-svn/page__view__findpost__p__5220
            if ((gpspositionsensor.PDOP < gpsSettings.MaxPDOP) && (gpspositionsensor.Satellites >= gpsSettings.MinSattelites) &&
                (gpspositionsensor.Status == GPSPOSITIONSENSOR_STATUS_FIX3D) &&
                (gpspositionsensor.Latitude != 0 || gpspositionsensor.Longitude != 0)) {
                AlarmsClear(SYSTEMALARMS_ALARM_GPS);
#ifdef PIOS_GPS_SETS_HOMELOCATION
                HomeLocationData home;
                HomeLocationGet(&home);

                if (home.Set == HOMELOCATION_SET_FALSE) {
                    setHomeLocation(&gpspositionsensor);
                }
#endif
            } else if ((gpspositionsensor.Status == GPSPOSITIONSENSOR_STATUS_FIX3D) &&
                       (gpspositionsensor.Latitude != 0 || gpspositionsensor.Longitude != 0)) {
                AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_WARNING);
            } else {
                AlarmsSet(SYSTEMALARMS_ALARM_GPS, SYSTEMALARMS_ALARM_CRITICAL);
            }
        }
    }
}

#ifdef PIOS_GPS_SETS_HOMELOCATION
/*
 * Estimate the acceleration due to gravity for a particular location in LLA
 */
static float GravityAccel(float latitude, __attribute__((unused)) float longitude, float altitude)
{
    /* WGS84 gravity model.  The effect of gravity over latitude is strong
     * enough to change the estimated accelerometer bias in those apps. */
    float sinsq = sinf(latitude);

    sinsq *= sinsq;
    /* Likewise, over the altitude range of a high-altitude balloon, the effect
     * due to change in altitude can also affect the model. */
    return 9.7803267714f * (1.0f + 0.00193185138639f * sinsq) / sqrtf(1.0f - 0.00669437999013f * sinsq)
           - 3.086e-6f * altitude;
}

// ****************

static void setHomeLocation(GPSPositionSensorData *gpsData)
{
    HomeLocationData home;

    HomeLocationGet(&home);
    GPSTimeData gps;
    GPSTimeGet(&gps);

    if (gps.Year >= 2000) {
        /* Store LLA */
        home.Latitude  = gpsData->Latitude;
        home.Longitude = gpsData->Longitude;
        home.Altitude  = gpsData->Altitude + gpsData->GeoidSeparation;

        /* Compute home ECEF coordinates and the rotation matrix into NED
         * Note that floats are used here - they should give enough precision
         * for this application.*/

        float LLA[3] = { (home.Latitude) / 10e6f, (home.Longitude) / 10e6f, (home.Altitude) };

        /* Compute magnetic flux direction at home location */
        if (WMM_GetMagVector(LLA[0], LLA[1], LLA[2], gps.Month, gps.Day, gps.Year, &home.Be[0]) == 0) {
            /*Compute local acceleration due to gravity.  Vehicles that span a very large
             * range of altitude (say, weather balloons) may need to update this during the
             * flight. */
            home.g_e = GravityAccel(LLA[0], LLA[1], LLA[2]);
            home.Set = HOMELOCATION_SET_TRUE;
            HomeLocationSet(&home);
        }
    }
}
#endif /* ifdef PIOS_GPS_SETS_HOMELOCATION */

/**
 * Update the GPS settings, called on startup.
 * FIXME: This should be in the GPSSettings object. But objects have
 * too much overhead yet. Also the GPS has no any specific settings
 * like protocol, etc. Thus the HwSettings object which contains the
 * GPS port speed is used for now.
 */
static void updateSettings()
{
    if (gpsPort) {
        // Retrieve settings
        uint8_t speed;
        HwSettingsGPSSpeedGet(&speed);

        // Set port speed
        switch (speed) {
        case HWSETTINGS_GPSSPEED_2400:
            PIOS_COM_ChangeBaud(gpsPort, 2400);
            break;
        case HWSETTINGS_GPSSPEED_4800:
            PIOS_COM_ChangeBaud(gpsPort, 4800);
            break;
        case HWSETTINGS_GPSSPEED_9600:
            PIOS_COM_ChangeBaud(gpsPort, 9600);
            break;
        case HWSETTINGS_GPSSPEED_19200:
            PIOS_COM_ChangeBaud(gpsPort, 19200);
            break;
        case HWSETTINGS_GPSSPEED_38400:
            PIOS_COM_ChangeBaud(gpsPort, 38400);
            break;
        case HWSETTINGS_GPSSPEED_57600:
            PIOS_COM_ChangeBaud(gpsPort, 57600);
            break;
        case HWSETTINGS_GPSSPEED_115200:
            PIOS_COM_ChangeBaud(gpsPort, 115200);
            break;
        }
    }
}

/**
 * @}
 * @}
 */