[Title Corrected] DEVICEID is NOT unique - it is "random" !

[awneil]

64 bit unique device identifier.
DEVICEID[0] contains the least significant bits of the device identifier. DEVICEID[1] contains the most significant bits of the device identifier.

infocenter.nordicsemi.com/.../ficr.html

Client wants a unique id - but would also prefer that products in a batch do not have sequential IDs.

Is it likely that chips on a reel will have sequential DEVICEIDs ?

[Jørgen Holmefjord]

Hi,

Each number is randomly generated, see this post. There is an extremely low probability that the chips on a reel will be sequential.

Best regards,
Jørgen

[Jørgen Holmefjord]

No, we can't guarantee that it is unique. But with 18446744073709551616 possible combinations, you should be quite unlucky to get numbers that are not unique.

We have never gotten any complaints or seen issues with this solution, and we use the number to uniquely identify chips ourselves.

[awneil]

But the fact remains that the documentation is incorrect.

Please update it to clearly state that it is random, not unique.

You could include the information about how it is generated, and the (un)likelihood of collisions - but don't lie!

It would save you having to keep answering the same question on the forum!

[awneil]

Jørgen Holmefjord said:

But with 18446744073709551616 possible combinations, you should be quite unlucky to get numbers that are not unique.

So is this basically the same premise as with UUIDs ?

"A little fun fact about UUIDs: There is no database ensuring that no one in the world is sharing the same UUID, but if you generate two random 128-bit UUIDs there is only a ~3e-39 chance that you will end up with two identical IDs (that is ~1/340,000,000,000,000,000,000,000,000,000,000,000,000)"

https://devzone.nordicsemi.com/nordic/short-range-guides/b/bluetooth-low-energy/posts/ble-services-a-beginners-tutorial

[Jørgen Holmefjord]

I have reported it internally.

[awneil]

Thanks.

[slight]

Is this still true? The nRF52833 datasheet says DEVICEID is unique. I understand that if it is random, there is very little chance that there will be a duplication, but it could be catastrophic if there was one.