nRF52832 BLE random static address uniqueness accross chip life

[vincent_itk]

Hi there,

We are using for BLE communication a nRF52832 chip with random static address configuration (shown in the UART). Can we be sure that the address of a chip will be always the same all accross the life of the product ? No way to change reflashing the chip, rebooting, erasing whole flash, locking the flash protection or any other possible action ?

We need this to be sure we can identify a device by his BLE MAC address (associated with its 8-byte device ID).

Nevertheless, we are away about uniqueness limitations of theses ID as explained :

• here about the MAC address  Does nRF52840 on Thingy 91 has unique MAC-address? 
• here about the hardware ID  nRF5340 FICR ID uniqueness 

Is theses ID are based from DEVICEID[0..1] from FICR https://docs.nordicsemi.com/bundle/ps_nrf52832/page/ficr.html#d917e1924 for the hardware ID and from DEVICEADDR[0..1] from FICR too https://docs.nordicsemi.com/bundle/ps_nrf52832/page/ficr.html#d917e6657 for the BLE address ?

Many thanks by advance.

[Hieu]

Hello vincent_itk,

Can we be sure that the address of a chip will be always the same all accross the life of the product ? No way to change reflashing the chip, rebooting, erasing whole flash, locking the flash protection or any other possible action ?

As long as you are using the default random static address without setting a different address or creating new Bluetooth identity, then you can be sure that it will stay the same. 

As you can find from the DevZone cases you linked, the default address is derived from factory written registers, which cannot be changed. Normal flash write and erase cannot change it.

In case it isn't obvious, this constancy only remains true if the device isn't later updated to set a different address or create a new Bluetooth identity.