listTopics

List all topics received by MAVLink client

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Syntax

topicTable = listTopics(mavlink)

Description

topicTable = listTopics(mavlink) returns a table of topics received on the connected mavlinkio client with information on the message frequency.

example

Examples

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Open Live Script

Create a MAVLink dialect object using the common.xml file.

dialect = mavlinkdialect("common.xml");

Create a local MAVLink client object that represents a simulated UAV. Specify these options:

  • MAVLink message definition — dialect

  • MAVLink system ID — 1

  • MAVLink component ID — 1

  • MAVLink component type — MAV_TYPE_QUADROTOR

  • MAVLink autopilot type — MAV_AUTOPILOT_GENERIC

uavClient = mavlinkio(dialect,SystemID=1,ComponentID=1,AutopilotType="MAV_AUTOPILOT_GENERIC",ComponentType="MAV_TYPE_QUADROTOR");

Connect the local simulated UAV to a random open UDP port by using the connect object function.

connect(uavClient,"UDP");

List all MAVLink clients that are connected to the simulated UAV by using the listClients object function. The output contains only the simulated UAV, which shows that no other MAVLink client is connected to the simulated UAV.

listClients(uavClient)
ans=1×4 table
    SystemID    ComponentID       ComponentType             AutopilotType     
    ________    ___________    ____________________    _______________________

       1             1         "MAV_TYPE_QUADROTOR"    "MAV_AUTOPILOT_GENERIC"

Launch QGroundControl.

To establish a connection with QGroundControl, first create a blank heartbeat message by using the createmsg object function.

heartbeat = createmsg(dialect,"HEARTBEAT");

Assign the component type and autopilot type of the simulated UAV, and the system status, to the heartbeat message fields.

heartbeat.Payload.type(:) = enum2num(dialect,MAV_TYPE=uavClient.LocalClient.ComponentType);
heartbeat.Payload.autopilot(:) = enum2num(dialect,MAV_AUTOPILOT=uavClient.LocalClient.AutopilotType);
heartbeat.Payload.system_status(:) = enum2num(dialect,MAV_STATE="MAV_STATE_STANDBY");

Create a timer callback function. Configure the callback function to send the heartbeat message to QGroundControl through a UDP connection using the sendudpmsg object function.

localHost = "127.0.0.1";
qgcPort = 14550;
heartBeatTimerFunction = @(~,~)sendudpmsg(uavClient,heartbeat,localHost,qgcPort);

Create a timer object with a fixed rate execution mode, period of 1 second, and the timer callback function. 

heartbeatTimer = timer(ExecutionMode="fixedRate",Period=1,TimerFcn=heartBeatTimerFunction);

Start the timer object. The local simulated UAV broadcasts the heartbeat message at 1 Hz, and QGroundControl connects to the simulated UAV.

start(heartbeatTimer)

List the MAVLink clients again to verify that QGroundControl is now connected. The output shows that QGroundControl is a connected MAVLink client with a component type of MAV_TYPE_GCS.

listClients(uavClient)

Once you have finished running the example, stop and delete the timer object to end the connection.

stop(heartbeatTimer)
delete(heartbeatTimer)

Input Arguments

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MAVLink client connection, specified as a mavlinkio object.

Output Arguments

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Topic info, returned as a table with SystemID, ComponentID, MessageID, MessageName, and MessageFrequency fields for each topic receiving messages on the client.

Version History

Introduced in R2019a

See Also

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External Websites