flight/modules/Example/examplemodcallback.c

   1 /**
   2  ******************************************************************************
   3  *
   4  * @file       examplemodcallback.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 "callbackinfo.h" // object needed for callback id macro CALLBACKINFO_RUNNING_<MODULENAME>
  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 #define STACK_SIZE        configMINIMAL_STACK_SIZE
  55 #define CALLBACK_PRIORITY CALLBACK_PRIORITY_LOW
  56 #define CBTASK_PRIORITY   CALLBACK_TASKPRIORITY_AUXILIARY
  57 // Private types
  58
  59 // Private variables
  60 static DelayedCallbackInfo *cbinfo;
  61
  62 // Private functions
  63 static void ObjectUpdatedCb(UAVObjEvent *ev);
  64
  65 static void DelayedCb();
  66 /**
  67  * Initialise the module, called on startup.
  68  * \returns 0 on success or -1 if initialisation failed
  69  */
  70 int32_t ExampleModCallbackInitialize()
  71 {
  72     // Listen for ExampleObject1 updates, connect a callback function
  73     ExampleObject1ConnectCallback(&ObjectUpdatedCb);
  74
  75     cbinfo = PIOS_CALLBACKSCHEDULER_Create(&DelayedCb, CALLBACK_PRIORITY, CBTASK_PRIORITY, CALLBACKINFO_RUNNING_EXAMPLE, STACK_SIZE);
  76
  77     return 0;
  78 }
  79
  80 /**
  81  * This function is called each time ExampleObject1 is updated, this could be
  82  * a local update or a remote update from the GCS. In this example the module
  83  * does not have its own thread, the callbacks are executed from within the
  84  * event thread. Because of that the callback execution time must be kept to
  85  * a minimum.
  86  */
  87 static void ObjectUpdatedCb(__attribute__((unused)) UAVObjEvent *ev)
  88 {
  89     PIOS_CALLBACKSCHEDULER_Dispatch(cbinfo);
  90 }
  91
  92 /**
  93  * This function is called by the PIOS_CALLBACKSCHEDULER_Scheduler when its execution
  94  * has been requested.  Callbacks scheduled for execution are executed in the
  95  * same thread in a round robin fashion. The Dispatch function to reschedule
  96  * execution can be called from within the Callback itself, in which case the
  97  * re-run will be scheduled after all other callback with equal or higher
  98  * priority have been executed.  Like event callbacks, delayed callbacks are
  99  * executed in the same thread context one at a time, therefore blocking IO
 100  * functions or very long lasting calculations are prohibited. Unlike Event
 101  * callbacks these callbacks run with a standard (IDLE+1) thread priority and
 102  * do not block regular threads. They are therefore saver to use.
 103  */
 104 static void DelayedCb();
 105 ExampleSettingsData settings;
 106 ExampleObject1Data data1;
 107 ExampleObject2Data data2;
 108 int32_t step;
 109
 110 // Update settings with latest value
 111 ExampleSettingsGet(&settings);
 112
 113 // Get the input object
 114 ExampleObject1Get(&data1);
 115
 116 // Determine how to update the output object
 117 if (settings.StepDirection == EXAMPLESETTINGS_STEPDIRECTION_UP) {
 118     step = settings.StepSize;
 119 } else {
 120     step = -settings.StepSize;
 121 }
 122
 123 // Update data
 124 data2.Field1    = data1.Field1 + step;
 125 data2.Field2    = data1.Field2 + step;
 126 data2.Field3    = data1.Field3 + step;
 127 data2.Field4[0] = data1.Field4[0] + step;
 128 data2.Field4[1] = data1.Field4[1] + step;
 129
 130 // Update the ExampleObject2, after this function is called
 131 // notifications to any other modules listening to that object
 132 // will be sent and the GCS object will be updated through the
 133 // telemetry link. All operations will take place asynchronously
 134 // and the following call will return immediately.
 135 ExampleObject2Set(&data2);
 136
 137 // call the module again 10 seconds later,
 138 // even if the exampleobject has not been updated
 139 PIOS_CALLBACKSCHEDULER_Schedule(cbinfo, 10 * 1000, CALLBACK_UPDATEMODE_NONE);
 140 }