MAVCONN library

It is mavlink connection and communication library used in MAVROS. Since 2014-11-02 it adopted to use outside from ROS environment by splitting to individual package and removing dependencies to rosconsole.

See the MAVROS documentation and the libmavconn API reference for more details.

Connection URL

Connection defined by URL. Just pass one of that URL to MAVConnInterface::open_url() and get connection object.

Supported schemas:

• Serial: /path/to/serial/device[:baudrate]
• Serial: serial:///path/to/serial/device[:baudrate][?ids=sysid,compid]
• Serial with hardware flow control: serial-hwfc:///path/to/serial/device[:baudrate][?ids=sysid,compid]
• UDP: udp://[bind_host][:port]@[remote_host][:port][/?ids=sysid,compid]
• UDP broadcast until GCS discovery: udp-b://[bind_host][:port]@[:port][/?ids=sysid,compid]
• UDP broadcast (permanent): udp-pb://[bind_host][:port]@[:port][/?ids=sysid,compid]
• TCP client: tcp://[server_host][:port][/?ids=sysid,compid]
• TCP server: tcp-l://[bind_port][:port][/?ids=sysid,compid]

Note: ids from URL overrides ids given by system_id & component_id parameters.

Dependencies

Same as for mavros:

• Linux host
• Asio library ( https://think-async.com/Asio/ )
• console-bridge library
• compiler with C++20 support

Shared io_service (optional)

By default each connection owns and runs its own asio::io_service thread. For multi-connection setups you can provide a shared asio::io_service and run it from your own thread pool.

#include <asio.hpp>
#include <mavconn/interface.hpp>

asio::io_service shared_io;
auto work = std::make_unique<asio::io_service::work>(shared_io);
std::jthread io_thread([&]() { shared_io.run(); });

auto conn = mavconn::MAVConnInterface::open_url(
  "udp://0.0.0.0:14555@127.0.0.1:14550",
  1, mavconn::MAV_COMP_ID_UDP_BRIDGE,
  [](const mavlink::mavlink_message_t *, mavconn::Framing) {},
  {},
  &shared_io);

conn->close();
work.reset();
shared_io.stop();

License

Licensed under terms of LGPLv3, BSD, or GPLv3.

Changelog for package libmavconn

2.16.0 (2026-09-27)

• Merge pull request #2290 from mavlink/fix-io-context libmavconn: fix IoContextRunner self-close lifetime and restart (fix #2275)
• libmavconn: fix IoContextRunner self-close lifetime and restart (fix #2275) On a shutdown initiated from the owned I/O thread (self-close), join_owned() detaches the worker thread. The runner then called restart() while run() was still active on that thread (undefined behaviour) and, after the worker detached, could be destroyed while the thread still wrote is_running_. Move the io_context, work guard, and is_running flag into a heap-shared State that the worker thread also holds. The worker restarts the io_context only after run() returns, and the State (and thus the io_context) survives even if the owning connection is destroyed before the detached thread completes.
• Merge pull request #2289 from mavlink/check-cbg plugins: fix cmd/command service deadlocks and const shared_ptr deprecation warnings
• libmavconn: consume nodiscard result in baudrate test The serial baudrate regression test calls open_url_no_connect() expecting it to throw DeviceError; the [[nodiscard]] return was left unconsumed, producing -Wunused-result warnings. Capture it in a [[maybe_unused]] variable.
• Merge pull request #2287 from christophebedard/christophebedard/fix-libmavconn-missing-ament-cmake-google-benchmark-dep
• Add missing test_depend on ament_cmake_google_benchmark to libmavconn It's used in tests since #2256, but it wasn't declared as a (test) dependency, resulting in build failures on the ROS 2 buildfarm: https://build.ros2.org/view/Hbin_uJ64/job/Hbin_uJ64__libmavconn__ubuntu_jammy_amd64__binary/160/console ` 23:58:37 CMake Error at CMakeLists.txt:117 (find_package): 23:58:37 By not providing "Findament_cmake_google_benchmark.cmake" in 23:58:37 CMAKE_MODULE_PATH this project has asked CMake to find a package 23:58:37 configuration file provided by "ament_cmake_google_benchmark", but CMake 23:58:37 did not find one. 23:58:37 23:58:37 Could not find a package configuration file provided by 23:58:37 "ament_cmake_google_benchmark" with any of the following names: 23:58:37 23:58:37 ament_cmake_google_benchmarkConfig.cmake 23:58:37 ament_cmake_google_benchmark-config.cmake`
• Contributors: Christophe Bedard, Vladimir Ermakov

2.15.1 (2026-08-22)

• libmavconn: fix serial baudrate parsing above uint16 url_parse_host hardcoded a uint16 port limit and error label, which rejected serial baudrates above 65535 (e.g. 921600) with a misleading 'invalid port value' error. Make the value range and field name configurable and allow baudrate to use the full int range. Adds a regression test covering a high valid baudrate and invalid zero/non-numeric baudrates. Fix #2265
• Merge pull request #2260 from mavlink/fix-deprecations Fix deprecations
• libmavconn: fix deprecated literal operator whitespace
• libmavconn: avoid -Wformat-security in format() with no args
• Contributors: Vladimir Ermakov

2.15.0 (2026-08-08)

• Merge pull request #2259 from mavlink/docs-refresh docs: refresh, refactor extractor

• docs: refresh subpackage READMEs

  - mavros: point the API docs link at readthedocs/plugin reference instead of the dead wiki.ros.org page; fix ROS1 roslaunch examples to ros2 launch; note that up-to-date install instructions live in the readthedocs guide.

  • mavros_extras: link to the full plugin reference.
  • libmavconn: link to the docs and API reference.
  • mavros_msgs: add the missing README (message/service overview + API links).
  • test_mavros: mark the ROS1-era SITL hand-tests as historical.

• Merge pull request #2256 from mavlink/try-optimize-router Optimize MAVROS router and MAVConn send path

• libmavconn: speed up utils::format with a stack-buffer fast path The old format() called snprintf twice (once to measure, once to fill) and wrote through &ret.front()/capacity(), which is UB for empty output. Format into a small stack buffer first (single snprintf), re-formatting into a heap string only when the output exceeds it. Handles encoding errors and the empty-output case.

• libmavconn: skip send post when chain active, use composed async_write Only the producer that turns the tx queue from idle to active posts a send handler; an in-progress chain drains everything enqueued meanwhile. This removes the per-message asio::post handler allocation and shared_from_this churn on the send path in steady state. Use composed asio::async_write for TCP/serial so partial writes are handled internally, deleting the manual MsgBuffer::pos tracking and resend loop (and the fragile capture of a reference into the tx queue).

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