Thread network commissionning (with Bluetooth)

[QuentinD]

Hello

I would like to commission my Thread network but my Thread network is isolated (I have no wifi) but I have bluetooth which works in parallel to the Thread network (app based on the "ble_thread_dyn_mtd_coap_cli_pca10056_s140" example ).

Would it be possible to use bluetooth to commission the Thread network (add a new device to the Thread network)? If yes, what do you advise me to be able to do that?

Thank you

[Edvin]

Hello QuentinD and HardikHarpal,

Sorry for the late reply. I pinged our Thread team, and they told me that this was apparently already a known issue, but the fix didn't make it before the SDK 4.1.0 freeze. 

The fix is included in this pull request:

https://github.com/openthread/openthread/pull/4788

As far as I know, the only way to patch this is to rebuild the openthread stack with this applied.

They said that they will check if there is a possible workaround, but as of now, a rebuild is required. 

Best regards,

Edvin

[QuentinD]

Hello Edvin,

I rebuiled OpenThread but unfortunately I still have the same problem ... I tested it with the example "ble_thread_dyn_mtd_coap_cli_pca10056_s140".

When I execute the "otCommissionerStart (...)" function, it returns "OT_ERROR_ALREADY" to me and then if I execute "otCommissionerAddJoiner (...)", it returns "OT_ERROR_INVALID_STATE".

And if I execute the "otCommissionerStop (...)" function before calling the "otCommissionerStart (...)" function, it returns "OT_ERROR_INVALID_STATE".

Do you have any idea when we can have a correction?
If the answer is no, is it possible to activate it by default (without having to activate it later in the application)? Or, do you have other ways to commission a new device on an existing Thread network?

Thank you

[Edvin]

Hello,

A new reply from our Thread team:

--

Hello,

The commissioner API exposes on-mesh commissioner API.

 

Note that the on-mesh commissioner feature is optional in Thread, and does not need to be used. The normal/regular commissioning
is done using external commissioner through e.g. mobile phone: https://openthread.io/guides/border-router/external-commissioning

I do see two problems here.

The first one is incorrect API usage, and the second is the bug in OpenThread described here: https://github.com/openthread/openthread/pull/4788
which is already fixed on master.

First of all, otCommissionerStart can be called only when device has already attached
to the network. Calling this API before will return error code as in your case.

For example, you can act on state change handler for example:

switch (otThreadGetDeviceRole(p_context))
 {
 case OT_DEVICE_ROLE_CHILD:
 case OT_DEVICE_ROLE_ROUTER:
 case OT_DEVICE_ROLE_LEADER:
 {
     otError error = otCommissionerStart(thread_ot_instance_get(), commissioner_state_callback, commissioner_joiner_callback, NULL);
     ASSERT(error == OT_ERROR_NONE);
     break;
 }

Only when state of the commissioner changes to `OT_COMMISSIONER_STATE_ACTIVE` you can call

otCommissionerAddJoiner

When it comes to the side-effect of using the OpenThread libraries as is in SDK 4.1.0, as explained
in the GitHub's Pull Request. Basically if Commissioner changes the state without user intervention
e.g. from Active to Disabled (due to some network issue e.g. Keep Alives are lost) without calling
the OpenThread API it may not be possible to turn on/off the commissioner again.
This should not be a blocker with the current OpenThread libraries.

The `OT_ERROR_ALREADY` error is a little bit misleading since it is returned from Border Agent module, not the Commissioner one:
https://github.com/openthread/openthread/blob/c6a258e3a5bd90aa26d8245c435c0ae5797027f4/src/core/api/commissioner_api.cpp#L54

Anyway, I would suggest to rebuild OpenThread libraries with the following commit which includes the fix: 2f618bd4a72501a2f31e23d50a4f388b9a8c6b9b

--

Try this.

BR,
Edvin

[QuentinD]

Hello,

Thank you very much for your help and all this information.

I use the on-mesh commissioner because I don't have a boarder router connected to the internet, as your example shows: I only have a smartphone that can connect to the device via Bluetooth.

Now I am no longer getting errors from these functions but still have problem in certain scenarios.

For example, if I do the simple procedure like this, it works (with the "thread_cli_ftd_uart_pca10056" exemple):
 

But if the 2 devices were on a different network before launching the commissioning, the commissioning fails:
 or 

Do you have any idea why commissioning fails when the 2 devices are not on the same network?

Thank you

[Edvin]

I am not sure I follow. Are they supposed to be commissioning when they are not on the same network?