Switching between random and normal mac address?

RE: Switching between random and normal mac address?

kerem — Wed, 02 Sep 2015 17:18:36 GMT

You were right, I edited my question with the working solution. It has nothing to do with reset, I just saved the initial value before randomizing and loaded it back to go back to normal. Done. Thank you.

RE: Switching between random and normal mac address?

Susheel Nuguru — Wed, 02 Sep 2015 05:00:06 GMT

any updates on this kerem?

RE: Switching between random and normal mac address?

kerem — Tue, 01 Sep 2015 13:21:43 GMT

Ok that makes sense, I think resetting was what's working for me. I'll update my answer after making sure that's the case.

RE: Switching between random and normal mac address?

Susheel Nuguru — Tue, 01 Sep 2015 13:01:10 GMT

I did not understand your comments. When the softdevice initializes it gets the device address and type from FICR and keeps the value inside its structures. when you change the value using sd_ble_gap_address_set, it does not change the value in FICR but changes it inside the softdevice structure (which is used in radio packets). This means that once you have called sd_ble_gap_address_set, softdevice completely forgot the original device address. It is upto the application to remember this before changing the value or the application can read it from FICR. So if you want the device address to reset to its inital state, you have to either restart the softdevice (like resetting the device) which will make the SD to fetch this value from FICR again or read FICR explicitly.

RE: Switching between random and normal mac address?

kerem — Tue, 01 Sep 2015 12:53:18 GMT

By the way, even after scrambling the mac address, a call to sd_ble_gap_address_get gives me the same original address so that's ok. This is again for sd 7.0 and sdk 6.1.

RE: Switching between random and normal mac address?

kerem — Tue, 01 Sep 2015 12:46:08 GMT

Using sd_ble_gap_address_get(&gap_address); fixed the problem, for some reason I was reading a different value which I see in the debugger.. Thank you.

RE: Switching between random and normal mac address?

Susheel Nuguru — Tue, 01 Sep 2015 12:17:23 GMT

You can do it in two ways

save the original one before changing it using sd_ble_gap_address_get

The Original device address is always present at NRF_FICR->DEVICEADD[0] and NRF_FICR->DEVICEADD[1]

You can fetch it by ble_gap_addr_t gap_address

   gap_address.addr_type     = NRF_FICR->DEVICEADDRTYPE & 0x01UL;
*((uint32_t PACKED *)&gap_address.addr[0]) = NRF_FICR->DEVICEADDR[0];
*((uint16_t PACKED *)&gap_address.addr[sizeof(uint32_t)]) = (NRF_FICR->DEVICEADDR[1] & 0x0000FFFFUL);

    err_code = sd_ble_gap_address_set(BLE_GAP_ADDR_CYCLE_MODE_NONE, &gap_address);

Since this is just reading, it can be done safely while softdevice is active.