cannot talk to dongle after connect

[JimmyD]

I connect to the nRF52840-MDK dongle thru the Serial Terminal (nRF52 Connectivity) it found the comm port and set the baudrate automatically. However, the terminal window constantly fills up the screen with ~/ characters. it repeats every 1 second. What I would like is detailed instructions on how to configure this dongle to be a BT 5 sniffer and read the Extended Advertising for any BT device near the dongle. It would also be helpful to filter the devices seen. Eventually I like to use Python to filter the choices and obtain the advertises data where I can parse the data received. I'm using Windows 10 pro.

Thanks.

[ovrebekk]

Hi Jim

Where you unable to filter out both types of packets in your script, either by filtering on RSSI or the MAC address? 

Again, to figure out how the packets are defined and how the first packet leads to the second you can use the Wireshark interface for reference:

As usual I am testing using the periodic_adv sample for reference. 

I can see that three packets are sent on the primary advertising channels, and if I open the Advertiser Aux Pointer under the Extended Advertising Header I can see the information pointing to further data on the secondary advertising channels. 

In this particular case I can see that there is a packet coming on channel index 22, and the time offset from the current packet is 1110 us. By setting the time reference to the current packet I can see that approximately 1110 us later a packet is received on channel 22, containing the actual advertising data:

The Advertiser Sync Info field in the extended advertising packet contains information about the rest of the packets in the periodic advertising stream, meaning it is not strictly necessary to receive all the packets on the primary advertising channels, a scanner could decide to simply listen for the packets on the secondary channels instead (as long as you manage to stay synchronized with the stream). 

When using the sniffer you don't need to manually handle the forwarding from the primary channel packets to the secondary channel packets, the sniffer will try to report all of them. It is more about defining the filters properly to only process the packets that you care about, that you know are sent by the right advertiser. 

What kind of results do you get when trying to filter on MAC address and/or RSSI? 

Are you not able to see the same data that the smart phone reports?

Best regards
Torbjørn

[JimmyD]

My Wireshark setup is different. Unfortunately I don't have time to spend on this issue now, but will need it for phase 2. I still can't seem to get the extended information I need. when I get a chance to get back to this project, I'll take a screen shot so  you see.

[ovrebekk]

Hi Jim

No problem, once you have had time to look into it just let me know. 

Best regards
Torbjørn

[JimmyD]

Torbjorn,

I started to look into this again. I modified your 'example_count_by_type_v2.py" to print out only selected mac addresses and the data in hex.

I noticed at the top of this file you including SnifferAPI. Since I'm new to Python, I presume that you are including everything in the subfolder named SnifferAPI. I started looking into these files and found one named "Types.py".  I cannot find the type "AUX_SCAN_RSP" it seems that WireShark was able to extract the data I need using this type. Is it possible to include this type while scanning and see the data of this type? Let me know if this edit is simple you can send it to me or send me a new file.  

Greatly appreciate it.

FYI: I'll be out tomorrow (Wednesday)  and return on Monday.

Jim D.

[JimmyD]

I did find ADV_TYPE_SCAN_RSP in Type.py, I think that this is a clue, but not sure if this is enabled, I'll need help.

Thanks again.