A.R.Drone Developer Guide - Abstract

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Listing 5.4: Example of navdata management function
/* Receving navdata during the event loop */
inline C_RESULT demo_navdata_client_process( const navdata_unpacked_t* const
navdata )
{
const navdata_demo_t* const nd = &navdata->navdata_demo;
}
printf("Navdata for flight demonstrations\n");
printf("Control state : %s\n",ctrl_state_str(nd->ctrl_state));
printf("Battery level : %i/100\n",nd->vbat_flying_percentage);
printf("Orientation : [Theta] %f [Phi] %f [Psi] %f\n",nd->theta,nd->phi,nd
->psi);
printf("Altitude : %i\n",nd->altitude);
printf("Speed : [vX] %f [vY] %f\n",nd->vx,nd->vy);
printf("\033[6A"); // Ansi escape code to go up 6 lines
return C_OK;
5.4 Command line parsing for a particular application
The user can implement functions to add arguments to the default command line. Functions
are defined in file :
• ardrone_tool_display_cmd_line_custom (Not mandatory): Displays help for particular
commands.
• ardrone_tool_check_argc_custom (Not mandatory) : Checks the number of arguments.
• ardrone_tool_parse_cmd_line_custom (Not mandatory): Checks a particular line command.
5.5 Thread management in the application
In the preceding section, we showed how the ARDrone application was initialized and how
it manages the Navdata and control events. In addition to those aspects of the application
creation, there are also smaller details that need to be considered before building a final application.
It’s the responsibility of the user to manage the threads. To do so, we must declare a thread
table with MACRO defined in vp_api_thread_helper.h file. Listing 5.5 shows how to declare a
threads table.
The threads navdata_update and ardrone_control do not need to be launched and released;
this is done by the ARDroneMain for all other threads, you must use the MACRO named
START_THREAD and JOIN_THREAD.