Mavlink messages to qgc

QGroundControl Development
1

Hi, a question about qgroundcontrol: I’m sending mavlink debug messages from px4 to qgc and i can see them in the MavLink Inspector, If i want for instance to print the debug msg payload on the Flight map, how can i do it? Maybe somebody can provide a simple example? According to the manual: all MAVLink messages are routed to Vehicle’s which are associated with the link by MAVLinkProtocol . So what object in Vehicle.h is handling the incommoding messages? Or maybe it is done elsewhere?

2

Hi,

Create a class (YourCustomClass) with an activeVehicle property :
Vehicle* activeVehicle;

And a slot to read messages :
.h

public slots:
  void readMavlinkMessage(const mavlink_message_t& message);

.cpp

void YourCustomClass::readMavlinkMessage(const mavlink_message_t& message){
    if(message.msgid == MAVLINK_MSG_ID_DEBUG){
        uint8_t ind = mavlink_msg_debug_get_ind(&message);
        qCDebug() << "Debug message index: " << ind;
    }
}

Connect the message received signal to the read slot :
QObject::connect(activeVehicle, SIGNAL(mavlinkMessageReceived(const mavlink_message_t&)), this, SLOT(readMavlinkMessage(const mavlink_message_t&)));

Add an instance of your custom class in CustomPlugin.h/.cc, and then from qml (for instance in CustomFlyView.qml) :

    Connections{
        target: QGroundControl.multiVehicleManager
        onActiveVehicleChanged: {
            QGroundControl.corePlugin.YourCustomInstance.activeVehicle = QGroundControl.multiVehicleManager.activeVehicle
        }
    }

Tom

1 Like
3

I have the same problem : thanks for these precious informations Tom ! I make it right !

I would like to speak with you a little about our project. There are others functionalities we need and you are surely the good person to ask for.

Mickaël.

4

Nethertheless, I lost something. In my case, I want to catch a specific mavlink message, got data and printed it in my modified FlyViewCustomLayer.qml as it said here : custom_build/FlyView.html
Nothing happens because I don’t know how to “add an instance of your custom class in CustomPlugin.h/.cc” because I’m not using the “custom-example” example, and I don’t have those classes…
Where can I put my instance to make it working with my version of QGC ?

Thanks a lot !

5

This way worked out for me to get debug messages on qgc view:

  1. Create debug variable in Vehicle.h class:

mavlink_debug_t debug_msg;

2. Crate Q_Property

private:
         mavlink_debug_t debug_msg;
public:
         Q_PROPERTY( int debug_ind  READ debug_ind    NOTIFY debug_ind_Changed)
         int debug_ind () { return debug_msg.ind; }

         Q_PROPERTY( float debug_value  READ debug_value  NOTIFY debug_value_Changed)
         float debug_value () { return debug_msg.value; }
signals:
         void debug_ind_Changed (int debug_ind);
         void debug_value_Changed (float debug_value );

3. Add message to mavlink message handler in Vehicle.c

switch (message.msgid) {
........
    /*My code*/
    case MAVLINK_MSG_ID_DEBUG:
        mavlink_msg_debug_decode(&message, &debug_msg);
        emit debug_ind_Changed(debug_msg.ind);
        emit debug_value_Changed(debug_msg.value);
        break;
        
  }

4.In qml file create label that shows the values

P.S. TomRvr thanks a lot for your reply!

2 Likes
6

Thank you for the valuable information. Is it possible to know how to implement this in recent times (QGC 2023 versions)? Since some definitions and classes in the Vehicle.h file have changed. I would really appreciate it :slightly_smiling_face: