nRF52-DK stops following a BLE connection after a small amount of time passes.

[tjhasan]

I am currently using a nRF52-DK to follow the connection between two external devices. I run the sniffer and start/stop the sniffing via Wireshark.

When I start sniffing, I can see the advertisement packets of the two devices. Then, I select to follow one of the devices. Once that device is followed, I connect the two external devices together. For a small amount of time, Empty PDU and Encrypted packets are shown in the window, but after a small amount of time (roughly around 3 to 5 seconds), the sniffer stops printing packets or packet data.

I'm assuming this is because of the hopping mechanism of BLE devices, but I was under the assumption that the nRF52-DK had the ability to follow a connection through the hopping sequence.

Any help would be appreciated.

[daviddedwin]

Please post:
1. Sniffer version used
2. DK version used
3. The wireshark capture file that you got after sniffing
4. Any other actions done on the devices to setup the connection.

Thanks

[tjhasan]

Forgot to mention some more details on the 2 .pcapng files I provided.

The "Pairing" .pcapng file shows the packets sniffed during the pairing process in which I supplied a Passkey as described in this document (Section 5).

The "Post-Pairing" .pcapng file shows the packets sniffed after the pairing has already taken place. This was done following the instructions shown in Section 5.5

[daviddedwin]

It looks like the pairing is using secure connections and the sniffer only supports the debug mode for secure connections. There is an example in this case to set the debug mode for secure connections so it can be sniffed by the sniffer. Alternatively you can downgrade to legacy passkey mode so the sniffer can sniff the connection.

Hope this helps, please accept my answer and upvote it.

Thanks

[tjhasan]

Thank you very much for your insight. I'm still fairly new to this so I apologize if this is a silly question, but how do I go about downgrading to legacy passkey mode? I'm assuming I would have to do it on one of the two devices I have (Samsung Galaxy Phone & Garmin Vivosmart 4). Could you by chance point me in the right direction for this?

Alternatively, how would I go about enabling debug mode for secure connections on my devices? The example that you linked to, I believe, shows a user asking about pairing their nRF82382 to nRF Connect and using a separate DK as a sniffer. But in my case, I'm trying to sniff the connection between a different set of devices.

[daviddedwin]

I had linked to the case where using the debug key for secure connections are described, but I see that the debug key setting is not so straight forward.

You can look at peer manager init (I checked on SDK 17.0.2 for the HID Mouse example) and set the LE Secure parameter to off, this should switch the pairing process to legacy.

static void peer_manager_init(void)
....

    sec_param.lesc=SEC_PARAM_LESC;