librid

An ASTM F3411 and DIN EN 4709-002 message encoding and decoding library written in the C programming language.

The library provides struct definitions for all Remote ID messages. It also provides accessor and mutator functions for all members of the structure. You should not access the struct members directly. Instead use the provided functions which will decode and encode the data to and from the correct wire format.

The library targets embedded systems with limited features. You can use it for example for building a Remote ID scanner or transmitter. While not limited to these, there are known live implementations done with both Espressif ESP-IDF and Nordic nRF Connect SDK (NCS).

Important

This is a read-only mirror of the repository. Actual developing happens elsewhere. I do monitor this repository though.

Naming Conventions

Naming of modules and variables mirrors naming from the ASTM F3411 standard.

Element	Pattern	Example
Functions	rid_<module>_<action>	rid_location_set_speed()
Types	rid_<module>_t	rid_basic_id_t
Enums	RID_<CATEGORY>_<VALUE>	RID_ID_TYPE_SERIAL_NUMBER
Constants	RID_<NAME>	RID_TRACK_DIRECTION_MAX

Functions generally follow the init, validate, get and set pattern.

Function	Description	Example
rid_<type>_init()	Initialize with defaults	rid_location_init()
rid_<type>_validate()	Validate structure	rid_location_validate()
rid_<type>_set_<field>()	Mutator	rid_location_set_speed()
rid_<type>_get_<field>()	Accessor	rid_location_get_speed()
rid_<type>_<enum>_to_string()	Enum to string	rid_height_type_to_string()
rid_<type>_to_json()	JSON serialization	rid_location_to_json()

Examples

See the examples directory for better usage examples.

Differences from the Open Drone ID library.

This library output is byte compatible with the Open Drone ID library which is the reference implementation. There are a couple of behavior differences though.

Clamp Instead of Reject

According to ASTM F3411-22, the ground speed in a Location message must be clamped to a maximum of 254.25 m/s. The vertical speed must be clamped to either -62 m/s or 62 m/s depending on direction.

"Ground speed of flight. This value is provided in meters per second with a minimum resolution of 0.25 m/s. Special Values: Invalid, No Value, or Unknown: 255 m/s, if speed is >= 254.25 m/s: 254.25 m/s"

"Vertical speed upward relative to the WGS-84 datum, meters per second. Special Values: Invalid, No Value, or Unknown: 63 m/s, if speed is >= 62 m/s: 62 m/s, if speed is <= -62 m/s: -62 m/s"

Open Drone ID rejects any input value outside the valid bounds. Instead of rejecting this library clamps the values.

Reject ASCII control characters

ASTM F3411-22 specifies the Self ID and Operator ID as ASCII text, a string of ASCII characters. It is unclear if ASCII control characters should be accepted.

This library only allows printable ASCII characters and NUL. It is possible that this requirement will be relaxed in the future. Open Drone ID does not do an ASCII character check and also allows bytes > 127.

Build

$ mkdir build && cd build
$ cmake -DRID_BUILD_EXAMPLES=ON -DRID_BUILD_TESTS=ON ..
$ make
$ ctest --verbose

Install

Build and install a shared library.

$ mkdir build && cd build
$ cmake -DCMAKE_INSTALL_PREFIX=/opt/librid -DBUILD_SHARED_LIBS=ON ..
$ make
$ sudo make install

Uninstall

$ cd build
$ sudo make uninstall

License

The MIT License (MIT). Please see License File for more information.