LibrePilot/flight/modules/Example/examplemodevent.c

/**
 ******************************************************************************
 *
 * @file       examplemodevent.c
 * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
 * @brief      Example module to be used as a template for actual modules.
 *             Event callback version.
 *
 * @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
 */

/**
 * Input objects: ExampleObject1, ExampleSettings
 * Output object: ExampleObject2
 *
 * This module executes in response to ExampleObject1 updates. When the
 * module is triggered it will update the data of ExampleObject2.
 *
 * No threads are used in this example.
 *
 * UAVObjects are automatically generated by the UAVObjectGenerator from
 * the object definition XML file.
 *
 * Modules have no API, all communication to other modules is done through UAVObjects.
 * However modules may use the API exposed by shared libraries.
 * See the OpenPilot wiki for more details.
 * http://www.openpilot.org/OpenPilot_Application_Architecture
 *
 */

#include "openpilot.h"
#include "examplemodevent.h"
#include "exampleobject1.h" // object the module will listen for updates (input)
#include "exampleobject2.h" // object the module will update (output)
#include "examplesettings.h" // object holding module settings (input)

// Private constants

// Private types

// Private variables

// Private functions
static void ObjectUpdatedCb(UAVObjEvent *ev);

/**
 * Initialise the module, called on startup.
 * \returns 0 on success or -1 if initialisation failed
 */
int32_t ExampleModEventInitialize()
{
    // Listen for ExampleObject1 updates, connect a callback function
    ExampleObject1ConnectCallback(&ObjectUpdatedCb);

    return 0;
}

/**
 * This function is called each time ExampleObject1 is updated, this could be
 * a local update or a remote update from the GCS. In this example the module
 * does not have its own thread, the callbacks are executed from within the
 * event thread. Because of that the callback execution time must be kept to
 * a minimum, if the callback needs to wait for I/O or other long operations
 * then a thread should be used instead (see ExampleModThread.c). This is
 * important since all callbacks are executed from the same thread, so other
 * queued events can not be executed until the currently active callback returns.
 */
static void ObjectUpdatedCb(UAVObjEvent *ev)
{
    ExampleSettingsData settings;
    ExampleObject1Data data1;
    ExampleObject2Data data2;
    int32_t step;

    // Make sure that the object update is for ExampleObject1
    // This is redundant in this case since this callback will
    // only be called for a single object, it is however possible
    // to use the same callback for multiple object updates.
    if (ev->obj == ExampleObject1Handle()) {
        // Update settings with latest value
        ExampleSettingsGet(&settings);

        // Get the input object
        ExampleObject1Get(&data1);

        // Determine how to update the output object
        if (settings.StepDirection == EXAMPLESETTINGS_STEPDIRECTION_UP) {
            step = settings.StepSize;
        } else {
            step = -settings.StepSize;
        }

        // Update data
        data2.Field1    = data1.Field1 + step;
        data2.Field2    = data1.Field2 + step;
        data2.Field3    = data1.Field3 + step;
        data2.Field4[0] = data1.Field4[0] + step;
        data2.Field4[1] = data1.Field4[1] + step;

        // Update the ExampleObject2, after this function is called
        // notifications to any other modules listening to that object
        // will be sent and the GCS object will be updated through the
        // telemetry link. All operations will take place asynchronously
        // and the following call will return immediately.
        ExampleObject2Set(&data2);
    }
}