With Virtual Connection

Create console application

Note: Rider will be used in this guide, you are free to choose any other IDE for C# that you prefer.

Open your IDE and select the Project Type: Console
Leave everything as default. You may choose a different project name if you wish.
Press Create to create a project.
You should now see the default project page.

Install Required NuGet Packages

Open the NuGet Package Manager and search for the Asv.Mavlink packet.
Install the latest version (this guide is relevant to version 4.0.0 and higher)

The DeepEqual package is also used in this guide for testing purposes.

Setup task completion source and cancellation token

Create a task completion source. You'll need it to wait for a response from the server.

var tcs = new TaskCompletionSource<HeartbeatPayload>();

Create a cancellation token source with a timeout. The cancellation token will trigger after 10 seconds. You can change this by setting a different time span.

var cancel = new CancellationTokenSource(TimeSpan.FromSeconds(10), TimeProvider.System);

Register a delegate that will be called when the cancellation token is canceled. This will stop tcs from running in a loop when the token fails.

cancel.Token.Register(() => tcs.TrySetCanceled());

Create virtual mavlink connection

Note: Virtual MAVLink connection is used for testing purposes only. You'll need to create a router for a real MAVLink connection. Refer to With Ardu SITL for more information.

Create a virtual connection.

var protocol = Protocol.Create(builder =>
{
    builder.RegisterMavlinkV2Protocol();
    builder.Features.RegisterBroadcastFeature<MavlinkMessage>();
    builder.Formatters.RegisterSimpleFormatter();
});

var link = protocol.CreateVirtualConnection();

Create a MAVLink client identity. Assign SystemId, ComponentId, TargetSystemId, and TargetComponentId. You can read more about it in the official mavlink guide.

var identity = new MavlinkClientIdentity(1,2,3,4);

Device creation

Create a packet sequence calculator.

// Class for calculating the next sequence number of a packet
var clientSeq = new PacketSequenceCalculator();

Provide core services with a log factory to create a logger and a different time provider. This class provides everything that your device or MAVLink microservice will use.

var clientCore = new CoreServices(
    link.Client, 
    clientSeq, 
    logFactory: null, 
    timeProvider: null, 
    new DefaultMeterFactory()
);

Create a default device id.

var deviceId = new MavlinkClientDeviceId("copter", identity);

Create a configuration for the vehicle client device.

var config = new VehicleClientDeviceConfig();

Finally, create an ArduCopter client device.

var arduCopter = new ArduCopterClientDevice(
    deviceId, 
    config, 
    ImmutableArray<IClientDeviceExtender>.Empty, 
    clientCore
);

Create mavlink server

Create a packet sequence calculator and core services for the server.

var serverSeq = new PacketSequenceCalculator();
var serverCore = new CoreServices(
    link.Server,
    serverSeq, 
    logFactory: null, 
    timeProvider: null, 
    new DefaultMeterFactory()
);

Create a heartbeat server.

var mavlinkServer = new HeartbeatServer(
    identity.Target, 
    new MavlinkHeartbeatServerConfig(), 
    serverCore
);

Send data from server to client

Asv.Mavlink uses the R3 library, which allows you to use a reactive programming approach. To catch data received from the server, subscribe to its source.

arduCopter.Heartbeat.RawHeartbeat.Subscribe(p =>
{
    if (p is null) // if we have no data we skip it
    {
        return;
    }
    
    // We use console to see that everything works fine
    Console.WriteLine($"Heartbeat type: {p.Type}, Heartbeat baseMode: {p.BaseMode}");
    tcs.TrySetResult(p); // here we get the result
});

tart the server (note: some servers may not have this method).

mavlinkServer.Start();

Create a variable to save the payload sent from the server.

HeartbeatPayload? payload = null;

Set the payload for the MAVLink package. This operation triggers the process that sends data to the client.

mavlinkServer.Set(p =>
{
p.Type = MavType.MavTypeBattery;
p.BaseMode = MavModeFlag.MavModeFlagGuidedEnabled;
Console.WriteLine($"From Server Type: {p.Type}, From server baseMode: {p.BaseMode}");
payload = p;
});

Get the result

var result = await tcs.Task;

Compare data

if (!payload.IsDeepEqual(result))
{
    Console.WriteLine("Result is not equal to payload from server");
}

Console.WriteLine("Payload from server is equal to result");

Code's output

Proper console output should look something like that:

From Server Type: MavTypeBattery, From server baseMode: MavModeFlagGuidedEnabled
Heartbeat type: MavTypeBattery, Heartbeat baseMode: MavModeFlagGuidedEnabled
Payload from server is equal to result

Process finished with exit code 0.

Complete code

using System.Collections.Immutable;
using Asv.Common;
using Asv.IO;
using Asv.Mavlink;
using Asv.Mavlink.Minimal;
using DeepEqual.Syntax;
using R3;

// Setup
var tcs = new TaskCompletionSource<HeartbeatPayload>();
var cancel = new CancellationTokenSource(TimeSpan.FromSeconds(10), TimeProvider.System);
cancel.Token.Register(() => tcs.TrySetCanceled());

// Virtual mavlink connection
var protocol = Protocol.Create(builder =>
{
    builder.RegisterMavlinkV2Protocol();
    builder.Features.RegisterBroadcastFeature<MavlinkMessage>();
    builder.Formatters.RegisterSimpleFormatter();
});
        
var link = protocol.CreateVirtualConnection();
//

// Client Device
var identity = new MavlinkClientIdentity(1,2,3,4);

var clientSeq = new PacketSequenceCalculator();
var clientCore = new CoreServices(
    link.Client, 
    clientSeq, 
    logFactory: null, 
    timeProvider: null, 
    new DefaultMeterFactory()
);

var deviceId = new MavlinkClientDeviceId("copter", identity);
var config = new VehicleClientDeviceConfig();

var arduCopter = new ArduCopterClientDevice(
    deviceId, 
    config, 
    ImmutableArray<IClientDeviceExtender>.Empty, 
    clientCore
);
//

// Heartbeat server
var serverSeq = new PacketSequenceCalculator();
var serverCore = new CoreServices(
    link.Server,
    serverSeq, 
    logFactory: null, 
    timeProvider: null, 
    new DefaultMeterFactory()
);

var mavlinkServer = new HeartbeatServer(
    identity.Target, 
    new MavlinkHeartbeatServerConfig(), 
    serverCore
);
//

arduCopter.Heartbeat.RawHeartbeat.Subscribe(p =>
{
    if (p is null)
    {
        return;
    }
    
    Console.WriteLine($"Heartbeat type: {p.Type}, Heartbeat baseMode: {p.BaseMode}");
    tcs.TrySetResult(p);
});

mavlinkServer.Start();

HeartbeatPayload? payload = null;
mavlinkServer.Set(p =>
{
    p.Type = MavType.MavTypeBattery;
    p.BaseMode = MavModeFlag.MavModeFlagGuidedEnabled;
    Console.WriteLine($"From Server Type: {p.Type}, From server baseMode: {p.BaseMode}");
    payload = p;
});

var result = await tcs.Task;

if (!payload.IsDeepEqual(result))
{
    Console.WriteLine("Result is not equal to payload from server");
}

Console.WriteLine("Payload from server is equal to result");

Last modified: 25 December 2024