Questions about Wi-Fi provisioning using Bluetooth LE

[Mohammad Afaneh]

I am using the existing nRF Connect SDK (v2.9.0) example of Wi-Fi provisioning using Bluetooth LE (https://github.com/nrfconnect/sdk-nrf/tree/main/samples/wifi/provisioning/ble) and it's working fine.

I am using a Bluetooth sniffer (RFcreations mini-moreph) to capture the communication during the process, and I can't figure out from the source code what the values sent in the packets correspond to, specifically the payloads in the commands and status messages. Examples of these values highlighted in the red box in the image below:

Can you point me to any documentation (or source code) that provides the corresponding meanings to the different values used?

Also, is there any documentation on the workflow and packet exchange during this process? maybe something like a message sequence diagram.

Thanks!

[Aleksander Nowakowski]

Hello, nice to meet you! Let me answer all your questions.

I'll be pointing to the source code of Android app "nRF Wi-Fi Provisioner".

The Wi-Fi Provisioning service has 3 characteristics:

https://github.com/NordicSemiconductor/Android-nRF-Wi-Fi-Provisioner/blob/70ad27852ee6c77a5aac6453db0109ae0abcad6a/lib/ble/src/main/java/no/nordicsemi/android/wifi/provisioner/ble/internal/ProvisionerBleManager.kt#L67-L70 

The first one, Version, can be read without security, other 2 require pairing.

All the data are encoded as ProtoBuf using these files: https://github.com/NordicSemiconductor/Android-nRF-Wi-Fi-Provisioner/tree/main/lib/ble/src/main/proto 

Version charactersitic is encoding using version.proto (Version type)

Control Point is using request.proto and response.proto (and common.proto) (Request and Response types)

Data Out characteristic is using result.proto (Result type).

Data Out is used to return Scan Results and Connection States.

Using my friend chat.gpt or https://www.protobufpal.com/ and providing the proto files I'm getting the following:

0x0110 represents a Result message where:

• Field 2 (state) is set
• Value is 1 → AUTHENTICATION

0x0210 represents a Result message where:

• Field 2 (state) is set
• Value is 2 → ASSOCIATION

You'll find all staes here: https://github.com/NordicSemiconductor/Android-nRF-Wi-Fi-Provisioner/blob/70ad27852ee6c77a5aac6453db0109ae0abcad6a/lib/ble/src/main/proto/common.proto#L69-L77 

0x0108 seems to be a Request GET_STATUS.

Either https://www.protobufpal.com/ or your image has the data in other endianness, so you may need to revert bytes.

[Aleksander Nowakowski]

For example, when we have 0x0110, the first selected message:
1. I think the data are 0x1001 
2. 0x10 = 0001 0000 = 00010 | 000 = value 2, integer -> this is a Result type, so field 2 is Connection State
3. 0x01 = integer value 1 -> AUTHENTICATION

[Mohammad Afaneh]

Thank you @Aleksander. That makes sense now!