Safety self-test library fails the TM12 test module

[DamienF]

What I'd like to ask on this community forum is, has anyone faced any issue integrating the STL library? An FAE is engaged on this issue, with no response as of yet. We have good overall success, with the exception of the TM12 module, which fails occasionally. The occasional nature of the failure makes it difficult to troubleshoot.

Note, the safety self-test library is an ST-provided library. We run it on the H7. Failures still occur in spite of following the guidelines in the STL integration guide UM2601.

[Tesla DeLorean]

For those playing along at home, what specifically does "TM12" test for, Google was unhelpful..

[DamienF]

Oh, TM12 is part of the library API. More context: usage of the aforementioned ST-provided library is under NDA between the end-user and ST and therefore its API isn't public. FYI the library belongs to one of the STM32Cube Expansion Packages, and only high level info is public, see here: https://www.st.com/en/embedded-software/x-cube-stl.html

In short, that library helps customers achieve their targeted safety integrity level (SIL2 for us).

The sense of my enquiry is to probe the community at large for any experience/trouble using that library on the H7, not necessarily to dig into the nitty gritty of the problem -- for which this forum may not be the right place.

[Tesla DeLorean]

Sure I understand the purpose of STL, honesty as an IC Design, QA and DFT/BIST guy I've have my concerns about how much reliance is sought from such.

But what specific facet is TM12 testing? Trying to understand why it might fail.

The H7 has caching, super scalar and potentially multi-processor, going on. Certainly things which would cause unpredictable results, perhaps metastability or race conditions.

The H7 supposedly have some FLASH level CRC self-check functionally, which I could never make work properly, and got no straight answers from ST, and now I'm not even sure they are claiming its a feature, that sort of broken. And I've got a background with LFSR, CRC, and ECC implementations..

[Petr Sladecek]

Hello,

as the library is delivered to authorized subjects exclusively, I would like to ask you kindly to use official ST support via local FAE responsible for the FW delivery as this public forum is not suitable area to solve such kind of issues. So far, I've information that the issue reported by customer is under wide ST internal investigation, FAE was informed about possible solution by ST safety expert and we are waiting for customer feedback.

Thank you for understanding.

Best regards,

Petr, ST application engineer

[DamienF]

Thanks Petr; that makes a lot of sense. I since have made good progress running the STL lib on an H7-based Nucleo board using a similar usage model as ours. I'm following up with my FAE on that topic.