Light Switch Example ( SDK for Mesh 2.0.0 )

[vijayrakesh]

Hi!

I have some doubt's on Light Switch example in SDK for Mesh V.2.0.0 

1. I'm able to connect using nRF Connect Android Application to Proxy Client and Server but when i send some data its getting disconnected. Where do receive smartphone sent data in nRF52832 program? Is there any particular data to send to turn the led ?

2.Apart from previous version SDK new version contains provisioner role, without this role only one client and three server can work as previous version of light switch example in latest version example?   

3.How to know the Unicast ID,Virutal ID and Group ID?

4.Which API will send a message with maximum length of data as unicast or broadcast and what is the maximum length can sent in mesh network?

Regards,

Vijay Rakesh

[Thomas Stenersen]

Hi Vijay,

First off, sorry for the wall of text, but I felt I had to provide a bit of explanation with my answers. Secondly, I would highly recommend you to have a look through the introductionary chapters in the Bluetooth Mesh Profile specification. It’s not a terrible read, and will help a lot when working with Bluetooth Mesh :)

1. When you program your board with one of the proxy examples, the device will start advertising the Mesh Provisioning Service as defined by the Mesh Profile specification. The service acts as a transport for the Bluetooth Mesh provisioning protocol. This means that the data written to the Data In characteristic has to be according to the provisioning protocol, if not, the device will disconnect. That’s probably what you’re expericencing.

   After provisioning is complete, the device will actually reset the GATT database and start to advertise the Mesh Proxy Service. This service acts as a generic transport for Bluetooth Mesh traffic. The mesh messages are forwarded as is over GATT. That means that in order to send data to the device, you actually need a full mesh stack on both sides. We have released iOS libraries and will also release a similar library for Android in the future. If you want to test provisioning over GATT now, you may try the open source BlueZ meshctl tool, but unfortunately we cannot provide support for that. Read more here: https://devzone.nordicsemi.com/f/nordic-q-a/33636/mesh-api-for-pb-gatt-provisioning-proxy-sample-code/129379#129379

2. In the nRF5 SDK for Mesh v2.0.0 we split out the provisioning role from the Light switch client example. We saw that there were some confusion about whether client models was tied to the provisioning role or not. The provisioner is separate from model types. Any node can have any combination of client and/or server models.
   In the new SDK, the provisioner example is set up for 1 client and N servers. I’d recommend reading the example README for more information about how it is set up: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.meshsdk.v2.0.1/md_examples_light_switch_README.html?cp=4_1_0_4_0

   If you use the Interactive PyACI as a provisioner you can set up the network as you’d like. Connecting any of the Simple OnOff Clients to any of the Servers :) There is a tutorial you can follow here: http://infocenter.nordicsemi.com/topic/com.nordic.infocenter.meshsdk.v2.0.1/md_scripts_interactive_pyaci_doc_demo_configuration.html?cp=4_1_0_2_0_2

3. The node’s unicast address (address of the primary element) should be printed in the RTT log after the device has been provisioned. The addresses are distributed by the provisioner and a node doesn’t have any fixed virtual address and/or group address. You can use the API provided by the Device State Manager (DSM) to access the local node’s addresses and keys, but again, it is the provisioner node’s job to add, remove and bind any of these.

4. Read about maximum data length here: https://devzone.nordicsemi.com/f/nordic-q-a/32854/max-size-of-data-to-send-from-one-node-to-other-ble-mesh

   In short, when using a custom model, the maximum data length is 384 - 4 - 3 = 377 bytes. The model should use access_model_publish() to transmit this data.

Hope this helps,
Thomas

[vijayrakesh]

Hi Thomas,

Thanks for the reply, Is there any app built with full mesh stack in iOS/Andriod ? If yes, please let me know the app name and also what data i have send to switch on/off LED.

[Thomas Stenersen]

Hi,

There should be an app using the iOS library out soon (pending App Store review, as I understand it), but  it's still in an early development stage. In that version I don't think you can control the LEDs from the phone, but set up the network s.t. the client will publish on/off messages to the server. I recommend using the Interactive Python interface right now as that is more flexible and mature.

Best,

Thomas