pymavlink

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Pymavlink

This is a Python implementation of the MAVLink protocol. It includes a source code generator (generator/mavgen.py) to create MAVLink protocol implementations for other programming languages as well. Also contains tools for analyzing flight logs.

Documentation

Please see ardupilot.orghttp://ardupilot.org/dev/docs/mavlink-commands.html (opens in a new tab) for mavlink command reference.

For realtime discussion please see the pymavlink Gitter channel (opens in a new tab)

Examples can be found in the repository (opens in a new tab) or in the ArduSub book (opens in a new tab)

Rust generation and MAVSpec/mavio interoperability are documented in generator/Rust/README.md (opens in a new tab).

Installation

Pymavlink supports Python 3. Python 2 support has been removed.

The following instructions assume you are using a Debian-based (like Ubuntu) installation.

Dependencies

Pymavlink has several dependencies :

- [lxml](http://lxml.de/installation.html) : for checking and parsing xml file 

Optional :

- numpy : for FFT
- pytest : for tests

On Linux

lxml has some additional dependencies that can be installed with your package manager (here with apt):

sudo apt install libxml2-dev libxslt-dev

Optional for FFT scripts and tests:

sudo apt install python3-numpy python3-pytest

Analogously you can install the required dependencies for pymavlink:

sudo apt install python3-lxml

Alternatively, in the unlikely event that your distribution (other than Debian and its derivatives like Ubuntu) does not feature that package, you may decide to use pip and install the missing dependency from its source tree:

sudo apt install python3-pip
sudo python3 -m pip install --upgrade lxml

Yet another alternative is to use brew, in perfect analogy to how it is described for the macOS.

On macOS

lxml's native dependencies (libxml2 and libxslt) can be installed with Homebrew (opens in a new tab) :

brew install libxml2 libxslt

Install the Python dependencies with pip so they land in the same Python environment as pymavlink (Homebrew's numpy/pytest install into Homebrew's own Python interpreter, which is typically not the one running pymavlink) :

python3 -m pip install --upgrade lxml

Optional for FFT scripts and tests:

python3 -m pip install --upgrade numpy pytest

On Windows

Lxml can be installed with a Windows installer from here : pypi.orghttps://pypi.org/project/lxml (opens in a new tab)

Installation

For users

It is recommended to install pymavlink from PyPI with pip, that way dependencies should be auto installed by pip.

sudo python3 -m pip install --upgrade pymavlink

Mavnative

Starting from September 2022, mavnative, a C extension for parsing mavlink, was deprecated and removed. Mavnative development was stalled for long time, it only supports MAVLink1 and doesn't get any fix on the protocol.

For developers

From the pymavlink directory, you can use :

(cd ..; git clone https://github.com/ArduPilot/mavlink.git)
MDEF=$PWD/../mavlink/message_definitions python3 -m pip install . -v

Since pip installation is executed from /tmp, it is necessary to point to the directory containing message definitions with MDEF. MDEF should not be set to any particular message version directory but the parent folder instead. If you have cloned from mavlink/mavlink then this is /mavlink/message_definitions . Using pip should auto install dependencies and allow you to keep them up-to-date.

Or:

python3 -m pip install .

Running the tests

From inside the pymavlink directory, fetch the message definitions alongside the checkout and run the suite with pytest:

(cd ..; git clone https://github.com/ArduPilot/mavlink.git)
MDEF=$PWD/../mavlink/message_definitions PYTHONPATH=.. python3 -m pytest

MDEF points at the message definitions used to generate the dialects; if you already have an ArduPilot checkout, point it at that mavlink/message_definitions instead. PYTHONPATH=.. imports the local checkout rather than a pip-installed copy.

Ardupilot Custom Modes

By default, pymavlink will map the Ardupilot mode names to mode numbers per the definitions in the ardupilotmega.xml (opens in a new tab) file. However, during development, it can be useful to add to or update the default mode mappings.

To do this:

• create a folder named .pymavlink in your home directory (i.e. $HOME on Linux, $USERPROFILE on Windows); and
• add a JSON file called custom_mode_map.json to this new .pymavlink folder.

The JSON file is a dictionary that maps vehicle MAV_TYPE (opens in a new tab) value to a dictionary of mode numbers to mode names. An example that duplicates the existing mapping for MAV_TYPE_FIXED_WING (enum value of 1) vehicles is as follows:

{
    "1": {
        "0":  "MANUAL",
        "1":  "CIRCLE",
        "2":  "STABILIZE",
        "3":  "TRAINING",
        "4":  "ACRO",
        "5":  "FBWA",
        "6":  "FBWB",
        "7":  "CRUISE",
        "8":  "AUTOTUNE",
        "10": "AUTO",
        "11": "RTL",
        "12": "LOITER",
        "13": "TAKEOFF",
        "14": "AVOID_ADSB",
        "15": "GUIDED",
        "16": "INITIALISING",
        "17": "QSTABILIZE",
        "18": "QHOVER",
        "19": "QLOITER",
        "20": "QLAND",
        "21": "QRTL",
        "22": "QAUTOTUNE",
        "23": "QACRO",
        "24": "THERMAL"
        "25": "LOITERALTQLAND",
        "26": "AUTOLAND",
    }
}

This custom_mode_map.json file can be used to:

• change the display name of an existing mode (e.g. change "TAKEOFF" to "LAUNCH");
• add a new mode (e.g. add "25": "NEW_MODE"); and
• add a mapping for an unsupported vehicle type (e.g. add a mapping for MAV_TYPE_AIRSHIP (enum value of 7) vehicles).

Notes:

• Whilst the MAV_TYPE and mode numbers are integers, they need to be defined as strings in the JSON file, as raw integers can't be used as dictionary keys in JSON.
• This feature updates the default definitions. You can use it to change the name-to-number mapping for a mode, but you completely can't remove an existing mapping.

License

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pymavlink is released under the GNU Lesser General Public License v3 or later.

The source code generated by generator/mavgen.py is available under the permissive MIT License.