flight/modules/Example/examplemodevent.c

   1 /**
   2  ******************************************************************************
   3  *
   4  * @file       examplemodevent.c
   5  * @author     The OpenPilot Team, http://www.openpilot.org Copyright (C) 2010.
   6  * @brief      Example module to be used as a template for actual modules.
   7  *             Event callback version.
   8  *
   9  * @see        The GNU Public License (GPL) Version 3
  10  *
  11  *****************************************************************************/
  12 /*
  13  * This program is free software; you can redistribute it and/or modify
  14  * it under the terms of the GNU General Public License as published by
  15  * the Free Software Foundation; either version 3 of the License, or
  16  * (at your option) any later version.
  17  *
  18  * This program is distributed in the hope that it will be useful, but
  19  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  20  * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  21  * for more details.
  22  *
  23  * You should have received a copy of the GNU General Public License along
  24  * with this program; if not, write to the Free Software Foundation, Inc.,
  25  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  26  */
  27
  28 /**
  29  * Input objects: ExampleObject1, ExampleSettings
  30  * Output object: ExampleObject2
  31  *
  32  * This module executes in response to ExampleObject1 updates. When the
  33  * module is triggered it will update the data of ExampleObject2.
  34  *
  35  * No threads are used in this example.
  36  *
  37  * UAVObjects are automatically generated by the UAVObjectGenerator from
  38  * the object definition XML file.
  39  *
  40  * Modules have no API, all communication to other modules is done through UAVObjects.
  41  * However modules may use the API exposed by shared libraries.
  42  * See the OpenPilot wiki for more details.
  43  * http://www.openpilot.org/OpenPilot_Application_Architecture
  44  *
  45  */
  46
  47 #include "openpilot.h"
  48 #include "examplemodevent.h"
  49 #include "exampleobject1.h" // object the module will listen for updates (input)
  50 #include "exampleobject2.h" // object the module will update (output)
  51 #include "examplesettings.h" // object holding module settings (input)
  52
  53 // Private constants
  54
  55 // Private types
  56
  57 // Private variables
  58
  59 // Private functions
  60 static void ObjectUpdatedCb(UAVObjEvent *ev);
  61
  62 /**
  63  * Initialise the module, called on startup.
  64  * \returns 0 on success or -1 if initialisation failed
  65  */
  66 int32_t ExampleModEventInitialize()
  67 {
  68     // Listen for ExampleObject1 updates, connect a callback function
  69     ExampleObject1ConnectCallback(&ObjectUpdatedCb);
  70
  71     return 0;
  72 }
  73
  74 /**
  75  * This function is called each time ExampleObject1 is updated, this could be
  76  * a local update or a remote update from the GCS. In this example the module
  77  * does not have its own thread, the callbacks are executed from within the
  78  * event thread. Because of that the callback execution time must be kept to
  79  * a minimum, if the callback needs to wait for I/O or other long operations
  80  * then a thread should be used instead (see ExampleModThread.c). This is
  81  * important since all callbacks are executed from the same thread, so other
  82  * queued events can not be executed until the currently active callback returns.
  83  */
  84 static void ObjectUpdatedCb(UAVObjEvent *ev)
  85 {
  86     ExampleSettingsData settings;
  87     ExampleObject1Data data1;
  88     ExampleObject2Data data2;
  89     int32_t step;
  90
  91     // Make sure that the object update is for ExampleObject1
  92     // This is redundant in this case since this callback will
  93     // only be called for a single object, it is however possible
  94     // to use the same callback for multiple object updates.
  95     if (ev->obj == ExampleObject1Handle()) {
  96         // Update settings with latest value
  97         ExampleSettingsGet(&settings);
  98
  99         // Get the input object
 100         ExampleObject1Get(&data1);
 101
 102         // Determine how to update the output object
 103         if (settings.StepDirection == EXAMPLESETTINGS_STEPDIRECTION_UP) {
 104             step = settings.StepSize;
 105         } else {
 106             step = -settings.StepSize;
 107         }
 108
 109         // Update data
 110         data2.Field1    = data1.Field1 + step;
 111         data2.Field2    = data1.Field2 + step;
 112         data2.Field3    = data1.Field3 + step;
 113         data2.Field4[0] = data1.Field4[0] + step;
 114         data2.Field4[1] = data1.Field4[1] + step;
 115
 116         // Update the ExampleObject2, after this function is called
 117         // notifications to any other modules listening to that object
 118         // will be sent and the GCS object will be updated through the
 119         // telemetry link. All operations will take place asynchronously
 120         // and the following call will return immediately.
 121         ExampleObject2Set(&data2);
 122     }
 123 }