Simultaneous LE and BR/EDR to Same Device Capable: false

[mikkaa]

Hoping someone can help. 

I am using an nRF52840 MDK USB dongle running nrf firmware in wireshark / nrf sniffer. I am attempting to sniff the bluetooth messages from my pool controller, so that i can then add the commands to an espcontroller (then add it into my home automation).

I am able so see and select the nrf sniffer for Bluetooth LE interface in the list in wireshark, then once selected, I can see the bluetooth pool controller in the list of devices in Wireshark.

I am able to see constantly updating SCAN_RSP, SCAN_SEQ and ADV_IND records in the list, while my iphone is NOT connected to the pool controller, but then once I connect to the bluetooth controller from my iPhone, the messages stop and I get a final message ADV_EXT_IND [malformed Packet]. Once i disconnect my phone from the pool controller, the messages start coming through again.

If i open one of the messages, I can see a value stating Simultaneous LE and BR/EDR to Same Device Capable (Host): false, and another stating Simultaneous LE and BR/EDR to Same Device Capable (Controller): false so i suspect i cannot connect multiple bluetooth devices to the controller. 

Is there a way to get around this to sniff the messages as i click buttons?

thanks in advance for your assistance

[mikkaa]

Thank you again for your assistance. I sat the bluetooth connector (plugged into a different port in my laptop) within 20cm from the pool controller and was able to capture messages (thank you). I have attached them here for your perusal.

Connection was made at 5854 and disconnection at 10280. I am pretty sure I sent around 6 commands from the phone/app,

1. medium pump speed
2. low pump speed
3. high pump speed
4. Auto controller
5. Manual controller
6. Disconnect

Can i just ask, I assume the protocol ATT is communication between the phone (app) and the pool controller. Should I be looking at the Send Write Command and within that the Handle and Value as the message attributes. AND should i be able to find the Service and UUID?

pool_sniffer_2.pcapng

Thanks for all your assistance again, this has been very educational.

[Vidar Berg]

It's hard to say what caused the poor reception earlier, maybe it was just the range, but I am glad to hear that you are able to follow the connection now.

mikkaa said:

Can i just ask, I assume the protocol ATT is communication between the phone (app) and the pool controller. Should I be looking at the Send Write Command and within that the Handle and Value as the message attributes. AND should i be able to find the Service and UUID?

Yes, you can see from the write request what the iPhone is sending to the pool controller. However, to know which characteristics it's writing to, you need to know how the attribute table is laid out on the server. This is not possible to tell with this sniffer trace alone because the iPhone did not perform a service discovery at the beginning of this connection, but rather relied on previously cached attribute handle values from the pool controller's GATT server.

Value written to attribute handle 0x20 (unknown characteristic):

Example of an attribute table (layout is found through the service discovery procedure):

You can clear the cache on the iPhone by toggling Bluetooth enable in Settings->Bluetooth (note: toggling Bluetooth enable from the access control center will not have the same effect), and therefore force the phone to perform a new discovery on the next connection. If you then sniff the connection you should be able to see which UUIDs the attribute handles belong to.

A more visual approach to finding out which characteristics the attribute handles are assigned to is to use the the Bluetooth Low energy app in nRF connect for desktop and connect it to your pool controller. There you can send write and read request to the various characteristics and the log view will show what handles it used.

[mikkaa]

That information is exceptional. Thank you very much for your help, and I will try out the nRF Connect desktop app to get the values. Thanks again for all your help.