Multiple SEM6000 Bluetooth sniffing with one nrf52840 dongle

[searcher_98]

I'm building a project where I need to sniff bluetooth data exchanged between a Voltcraft SEM6000BT plug and my phone app. The idea here is to capture the BTATT (where the power, voltage, current etc are) data using Wireshark and a nrf52840 dongle. I was able to capture all the BTATT packets when using only one SEM6000 connected to the app as you can see in the print screen below.

But when I connect 2 smart plugs on the phone app, wireshark stops showing the BTATT packets when I select the "All advertising devices" as a filter in Wireshark, so I can't see these packets when using multiple plugs. Sometimes it works, but only if I select one plug only MAC address in the 'Device' filter, but when I do this, wireshark don't show the other plug's data logically.

I'm not a Wireshark expert, so maybe I'm missing something, but do you know if this have to do with a wireshark configuration that I have to do or if this can be a problem with the plug phone app or something else? In my phone app I still can see all the measurements.

PS: I tested using two dongles, each pointing to one different device (smart plug) in the same Wireshark instance and it works, but I would like to know if I could do this using only one nrf52840 dongle, or will I need one dongle for each smart plug?

Thanks for your help.

[Sigurd]

Hi!

"All advertising devices"

This will not follow the devices into connection state, it only shows advertising.

PS: I tested using two dongles, each pointing to one different device (smart plug) in the same Wireshark instance and it works, but I would like to know if I could do this using only one nrf52840 dongle, or will I need one dongle for each smart plug?

Yes, correct, if you want to sniff 2 connections at the same time, you need two dongles.

[searcher_98]

Thanks for the answer!

I have another question, for the moment, to be able to intercept BT data between the plug and my cellphone, I'm obliged to have my cellphone app open all the time, but that's not praticable as a final solution since we'll not have a cellphone with the app opened all the time.

Is there a way to use to nrf52840 dongle to mimic the cellphone as a destination device to receive the BT packets directly from the plug without needing the cellphone?

I tried for exemple to use Bluestack to emulate android over the pc and downloading the app, but neither Bluestack or any other android emulator support Bluetooth.

[Sigurd]

You could perhaps use the BLE app in nRF Connect for Desktop, and use e.g. another nR52840 dongle as the central, and use that to connect to the Voltcraft plug.

https://www.nordicsemi.com/Products/Development-tools/nRF-Connect-for-Desktop

[searcher_98]

Do I have to use the same firmware used with the other dongles? The sniffer firmware

[Sigurd]

No, it's a different FW for the BLE app. You should get a pop-up when you try to run the BLE app on the dongle, to flash the correct FW.

[searcher_98]

Perfect, that worked, thanks.

But I still don't get the BTATT packet with the data that I need in Wireshark, I could connect to the device using Nrf Connect, but I don't understand how it works and if I have to do something to be able to capture the same packets that the mobile app do, since I'm new to Nrf Connect. Below is my Nrf Connect screen.

Do you have a tutorial on how can I do it? I think the command the phone sends to get the BTATT data back is the following.