NRF_MESH_EVT_MESSAGE_RECEIVED mesh event behaviour

[Chris_Dev]

Hi all!

I am using mesh sdk v4.10 and sdk 16.0 with an nrf52840 custom hardware. I have a question regarding the mesh event handler. I am seeing something weird which I don't understand.

I have added the mesh event handler by doing the following:

  m_evt_handler.evt_cb = SM_mesh_event_handler;
  nrf_mesh_evt_handler_add(&m_evt_handler);
  
 void SM_mesh_event_handler(const nrf_mesh_evt_t *p_evt)
{
    switch (p_evt->type)
    {
    case NRF_MESH_EVT_MESSAGE_RECEIVED:
    {
        system_monitor.message_rx_count++;
    }
    break;

    case NRF_MESH_EVT_TX_COMPLETE:
    {
        system_monitor.message_tx_count++;
    }
    break;


    default:
    {
    /*Do nothing here*/
    }
    break;
    }
}

I have a node which publishes sensor status messages. The node is publishing to group 0xC000. What I am seeing is the following:

1. Node publishes the message and repeats it 2 times

2. NRF_MESH_EVT_TX_COMPLETE occurs

3. The weird part, NRF_MESH_EVT_MESSAGE_RECEIVED  occurs as well. The number of times this happens is exactly half of the NRF_MESH_EVT_TX_COMPLETE count.

There are no other nodes turned on. Also, the nrf52840 is half duplex.

Could someone please explain this behavior to me?

Regards

Chris

[Joakim Jakobsen]

Hi Chris.

Do you have the node subscribing to group address 0xC000? If so, it should receive the message that you are sending.

The NRF_MESH_EVT_MESSAGE_RECEIVED will only occur once, as it will disregard the second message if it's repeated from the sender.

Best regards,
Joakim

[Chris_Dev]

Hi Joakim, thank you for reply.

No it's only publishing to 0xc000. And it's only one node, that is on, there are no other nodes. According to that event, the node is seeing it's own message that is being sent:/

[Joakim Jakobsen]

Oh, I misread the question. I thought you were talking about two different nodes.

Are you seeing this with the one of the stock examples in the Mesh SDK?

Best regards,
Joakim

[Chris_Dev]

I just tried it with the light lightness client example, adding an event handler by using:

nrf_mesh_evt_handler_add()

It does not seem to happen in this example!

I do have another codebase which consists of Nordic implemented client models:

1. Generic on/off client

2. Generic level client

3. Generic on/power up client

4. Light Lightness client

5. Light LC client

The exact same thing is happening with all these models as well, every time I publish a message i.e generic on/off set, I get the  NRF_MESH_EVT_MESSAGE_RECEIVED event on the node that sent the message.

Here is a snip of the Call Stack:

Going all the way down to static bool loopback_process(void) in core_tx_local.c, I see there is some "loopback" source called .source = NRF_MESH_RX_SOURCE_LOOPBACK, so it seems like the node is "echoing" it's transmitted messages, almost like a simple UART test where you connect TX with RX, just with the radio of course. This looks like some debugging functionality....

Perhaps it's something you can disable in the stack?