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Query on Class B library - STM32U585 MCU

Associate III

Hi team;

We have selected Trust zone MCU STM32U585ZIT6Q (U5 series) for our project.
We are using with Trust zone enable in our project.
we have a query regarding the X-CUBE-CLASSB-U5.
We have taken library of X-CUBE-CLASSB-U5 and test example code in STM32CubeIDE and its working fine
But in our case all peripheral are in Non secure zone.and X-CUBE-CLASSB-U5 library is in Trust zone
so we have below queries
1) Can we use X-CUBE-CLASSB-U5 library in non secure zone
2) If we use X-CUBE-CLASSB-U5 in secure zone then will it hold our thread execution from non secure zone, while control goes to secure zone for STL functions?
3)if my peripheral is non secure side so how to check this peripheral through STL lib
Please guide us for same.
Thank you.

Petr Sladecek
ST Employee


you can find the answers at UM2893 delivered with the FW. Please read carefully end of chpt 3.1 and/or 4.3.12 especially, example 5 at Figure 5 and many other specific aspects when Trust zone is enabled. At principle, STL must be executed in Secure state. If the STL needs to be executed from non-secure state, then it must be called via the SG (secure gateway) feature.

Best regards,