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.

Warning

MavNet can send real arm, takeoff, land, and RTL commands. Start with PX4 SITL, keep props off real vehicles, and treat every connection string as capable of moving hardware.

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Add project references while the package is unpublished: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