A.R.Drone Developer Guide - Abstract

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Listing 5.6: The video pipeline
typedef struct _vp_api_io_stage_
{
//Enum corresponding to the type of stage available, include in file .
//Only used for Debug.
VP_API_IO_TYPE type;
//Specific data to the current stage. Definitions are given in include files <
VP_Stages/*> .
void *cfg;
//Structure {vp_api_stage_funcs} is included in with the
definition of stages.
Stages are included also in the directory Soft/Lib/ardrone_tool/Video.
vp_api_stage_funcs_t funcs;
/ /This structure is included in the file and is shared between
all stages. It contains video
buffers and information on decoding the video.
vp_api_io_data_t data;
} vp_api_io_stage_t;
Definition of the structure of a pipeline:
The structure is included in file :
typedef struct _vp_api_io_pipeline_
{
//Number of stage to added in the pipeline.
uint32_t nb_stages;
//Address to the first stage.
vp_api_io_stage_t *stages;
//Must equal to NULL
vp_api_handle_msg_t handle_msg;
//Must equal to 0.
uint32_t nb_still_running;
//Must equal to NULL.
vp_api_fifo_t fifo;
} vp_api_io_pipeline_t;
5.7 Adding control devices
The ARDroneTool and demonstration programs come with an example of how to use a gamepad
to pilot the drone.
The gamepad.c[pp] files in the example contain the code necessary to detect the presence of a
gamepad, poll its status and send corresponding commands.
To add a control device and make ARDroneTool consider it, you must write :
• an initialization function, that ARDroneTool will call once when initializing the application.
The provided example scans the system and searches a known gamepad by looking
for its USB Vendor ID and Product ID.
• an update function, that ARDroneTool will systatically call every 20ms during the application
lifetime, unless the initialization fails
• a clean up function, that ARDroneTool calls once at the end of the application