MAC Address ramdonly changing while advertising

[Gabriel Pinto]

Hello, I'm using the nrf52840 dev kit with softdevice s140 and nrf52 SDK to advertise a beacon.

I've noticed that the device has a "regular" MAC address  which is the one that shows up in the nrf Connect app when I scan the beacon, however, as I'm logging the beacons and respective MAC address I've noticed that the same device has had 8 different MAC addresses (even if just momentarily) over the course of a full day, this is a problem for me because I'm going to log the beacons based on their MAC address and I'm going to have multiple in the future so this address should be static and unique to each device.

Am I missing some configuration to make the mac address to be static?

Thanks in advance.

Gabriel

[Gabriel Pinto]

Hi Hung, 

Sorry for taking so long to answer but I had to put this issue on hold as it wasn't a priority at the time.

I'll try to follow up on your questions:

Hung Bui said:

You mentioned about a pattern 0xF6FF59, what is that ?

This is the raw data at the start of the beacon I get in my NRF Connect app. Rephrasing my previous comment I believe this to be specific manufacturer data of the nrf52840 chip, not the pca10059 board, I did not add this manually. The beacon always starts like that, don't know if it's from some of the configs or hard coded. 

Hung Bui said:

Please show how exactly you set up the advertiser and how you do filter on the scanner. 

I could share my script, but it's essentially a basic scanner that's getting the beacon and checking the beginning for the 0xF6FF59 code, if it has that then it gets the MAC address and the rest of the beacon payload. I don't have any other nrf device connect that can justify the MAC address change, furthermore the payload is the same when the MAC address changes. 

Thanks for the support.

[Learner]

Good Morning Gabriel,

Thank you for your reply. I will keep an eye on this case ID just in case a solution is provided.

The other comment I would like to add is this,

According to the logs from bt_hci_core,

[00:01:16.123,931] <inf> bt_hci_core: Identity: C7:2A:7D:C9:44:39 (random)

The MAC address is supposed to be random, yet every time I reset my device after I notice a change in its MAC address, it reverts back to the old address. This does not look like a random address. So, what is meant by 'random' in this context?

Kind regards

Mohamed