RM0454 chapter 30 is missing UID information

[Kraal]

Hi,

Chapter 30 in RM0454 (page 980) is missing the information about the unique device identifier.

It is very well described in the F0 RM0091, and I would like the same level of information to be added in the next revision of RM0454.

For the time being, can I suppose that I can follow F0 UID for G0 ?

Thank you very much.

[waclawek.jan]

Some of the Value-line (zero-ending part number) parts don't have Unique-ID (you may be able to read out some number, but its unique-ness is not guaranteed). If it's not in the RM, consider it not being there, and you should not rely on it.

See RM0444 for non-value-line 'G0.

JW

[Kraal]

Hi @Community member​ ,

Thank you for the information, I did not know that.

I don't understand why it would be removed for Value-lines parts fabrication lines, since UID is usually made of X-Y on the wafer, wafer number and lot number. So the information should be already available.

On top of that the UID flash location is explicitely mentionned in "stm32g070xx.h" and when I read it with the ST-Link I get the expected 12 bytes (they look like real information).

Since I have some nucleos lying around I will check for uniqueness.

Still, if anyone from ST can check and report if the info is missing from the RM, or if the info will never be there for the reason mentionned by @Community member​, that would be great.

Best regards.

[Peter BENSCH · Accepted solution]

@Community member​ is absolutely right in his statement. The section Unique device ID register (96 bits) is completely missing from RM0454 because the content of this location is not guaranteed.

The fact that the header file stm32g070xx.h contains the address UID_BASE does not necessarily mean that it can be used meaningfully - the respective data sheet is always decisive for the guaranteed functionality.

Regards

/Peter

[Kraal]

Thank you @Peter BENSCH​ for the quick confirmation.

I agree that the datasheet must be the only decisive document, provided it is up to date and error free.

I wish everyone a nice weekend,

Kraal

[waclawek.jan]

> I don't understand why it would be removed for Value-lines parts

There may be technicalities involved, but most likely ST simply wants you to buy the more expensive part if you want certain functionalities.

I think this is quite understandable strategy from a manufacturer's point of view.

You always can program an individual serial number yourself during manufacturing, so this is just simply transferring some of the burden from ST to you, so it's not some prohibitive drawback.

JW

[Peter BENSCH]

> ST simply wants you to buy the more expensive part if you want certain functionalities.

This may seem so from the point of view of users, but it does not get to the heart of the matter.

The fact is that the production of all chips is very costly, above all every single function must be guaranteed, which includes extensive testing. And this is exactly one of the crucial points: every single test step costs time and thus money, which of course affects the final price.

The STM32s of the Value Lines are now optimised for particularly low costs, where everything that can be omitted has been left out. For this reason, sometimes limited voltage values are guaranteed (e.g. can only be used from 2.0V) or the Unique ID function is no longer guaranteed.

But as Jan said, you can also store a serial number in the flash.

Regards

/Peter

[Kraal]

Hi @Peter BENSCH​ ,

Thank you, now I understand how it works in production.

Just like some parts are supposed to be 64k of flash only and yet sometimes you can have a bigger quantity available through the code, except that only 64k are garanteed to be tested and functionnal.

It makes sense for me and I will generate my own serial numbers during production.

Thank you both @Peter BENSCH​ and @Community member​ for the explanations.

Have a nice day,

Kraal

[Peter BENSCH]

Great!

When your question is answered, please mark this topic as answered by choosing Select as Best for the preferred answer, as also explained here. This will help other users find that answer faster.

Regards

/Peter