MavNet

MavNet

MavNet is a small .NET MAVLink v2 stack for UDP vehicle links. It gives you typed MAVLink messages, a UDP transport, and a PX4-oriented Drone facade for common telemetry and commands.

Status

• Target framework: net10.0
• Transport today: UDP
• Dialect today: common.xml (PX4-oriented)
• High-level vehicle facade today: PX4 multirotor (Drone)
• Package status: not published to NuGet yet
• Tests: xUnit + FluentAssertions across all layers, CI on Ubuntu + Windows

Where we stand: roughly 20–25% of a full general-purpose C# MAVLink SDK. The wire-format core, codegen pipeline, UDP transport, send path, and command-ACK correlation are solid. The protocol surface above that is still thin.

Roadmap

A condensed view. Full version in ROADMAP.md.

Done

• MAVLink v2 frame decode / CRC / truncation / forward-compat
• Codegen from common.xml (single dialect)
• UDP transport + heartbeat + typed dispatcher events
• Zero-alloc static-abstract send path
• PX4 Drone facade: arm, disarm, takeoff, land, RTL with COMMAND_ACK correlation
• Mission protocol: upload / download / clear / start state machines for waypoints, geofence and rally points; live MISSION_CURRENT / MISSION_ITEM_REACHED on Vehicle
• Rate-controlled state subscription
• Test harness, CI matrix, codegen-drift check, SourceLink, deterministic builds
• Static analysis: .NET analyzers (Recommended + code-style in build, generated code excluded), allowlist→IMavlinkConnection wiring consistency test

Next, in order

Milestone	Scope
M2	Parameter Protocol: PARAM_REQUEST_LIST / VALUE / SET with cache and ACK correlation
M3	Transports: TCP, serial; URI-driven MavlinkConnection.Open(...)
M4	Dialect-agnostic core + ArduPilot (ardupilotmega.xml, Copter/Plane/Rover facades)
M5	Telemetry rate control (SET_MESSAGE_INTERVAL) + LinkHealth (rtt, packet loss)
M6	FTP (msgid 110) + dataflash log download + TLOG write/read
M7	MAVLink v2 signing (HMAC-SHA256) + multi-link routing / bridging
M8	Camera v2, Gimbal v2, gripper, winch, component-aware addressing

Each milestone is a thin vertical slice — code + tests + docs, NuGet-shippable. v1.0 lands after M8.

Quick Start

Add project references while the package is unpublished:

<ItemGroup>
  <ProjectReference Include="path/to/MavNet/src/MavNet.PX4/MavNet.PX4.csproj" />
</ItemGroup>

Connect to PX4 SITL:

using MavNet.Core;
using MavNet.PX4;
using MavNet.PX4.Vehicles;

await using Drone drone = await Drone.ConnectAsync(
    "udp://0.0.0.0:14550?rhost=127.0.0.1&rport=18570",
    TimeSpan.FromSeconds(30));

using StateSubscription sub = drone.SubscribeState(
    s => Console.WriteLine($"{s.Mode} armed={s.Armed} alt={s.Alt:F1}m bat={s.Battery:F0}%"),
    StateRate.Hz(2));

CommandOutcome outcome = await drone.ArmAsync();
Console.WriteLine(outcome.Result);

Run the bundled probe:

dotnet run -c Release --project examples/MavNet.Probe -- "udp://0.0.0.0:14550?rhost=127.0.0.1&rport=18570"

Probe keys: A arm, D disarm, T takeoff to 10 m, L land, R return to launch, M mission demo (upload + start a square around the current position), Q quit.

Connection Strings

udp://localHost:localPort?rhost=remoteHost&rport=remotePort

Example for local PX4 SITL:

udp://0.0.0.0:14550?rhost=127.0.0.1&rport=18570

Defaults are localHost=0.0.0.0, localPort=14550, rhost=127.0.0.1, and rport=18570.

Build

dotnet build MavNet.slnx

Warnings are errors. Generated protocol files are committed, so a normal build does not require regeneration.

Generated Protocol Code

Generated files live under:

• src/MavNet.Protocol.Generated/
• src/MavNet.Protocol/Generated/MessageRegistry.cs

Do not hand-edit them. Regenerate with:

dotnet run --project tools/MavNet.CodeGen

When adding a message to tools/MavNet.CodeGen/allowlist.txt, regenerate, then add its typed event and dispatch case in src/MavNet.Transport.Udp/MavlinkConnection.cs. Surface it through Vehicle or Drone only when it belongs in the high-level API. AllowlistWiringConsistencyTests fails the build if the IMavlinkConnection event for an inbound message is forgotten (send-only messages are listed explicitly).

Docs

The full documentation site is published to GitHub Pages on every push to main.

Conceptual articles live in docs/articles/ as plain Markdown. API reference is generated automatically from /// XML comments in source.

Edit and preview locally:

dotnet docfx docfx.json --serve --watch

Open http://localhost:8080. The site rebuilds automatically when you save a Markdown file.

Build without serving:

dotnet docfx docfx.json

Output goes to _site/ (git-ignored).

Articles:

• Getting started
• Architecture
• Missions