Is nrf51 DEVICEID unique?

[pablo]

Hi,

I have read several threads on the devzone that points to the DEVICEID being randomly generated and not unique. At the same time chapter 7.4 in the Reference Manual says the DEVICEID is a "64 bit unique device identifier" (though it does not mention the generation method).

My question is: Can I use the 64-bit DEVICEID field to uniquely identify a nrf51 chip?

[Hung Bui]

Hi Pablo,

The DEVICEID is randomly generated using FIPS approved random number generator during production process. There is a slight chance that you have 2 chips with same DEVICEID but the possibility's very small given the high amount number of bits (= 1/(2^64) = 5.42*10^-20) .

[pablo]

Ok. So it is not unique. Given the FIPS RNG, is it safe to assume that using only DEVICEID[0] would result in a 1/(2^32) risk of collision between two devices?

[Hung Bui]

Yes, it's correct.

[awneil]

pablo said:

Reference Manual says the DEVICEID is a "64 bit unique device identifier"

It still says it - and it is still wrong!

https://devzone.nordicsemi.com/f/nordic-q-a/49664/deviceid-is-unique---but-is-it-random/198061#198061