What is NVSTATE in RM0481 rev 4?

[JesperEC]

In RM0481 rev 4 April 2025 I find the following text:

7.6.8 Write protection

A write-protected group of sectors cannot be erased nor programmed. As a result, a bank
erase cannot be performed if one group of sectors is write-protected, unless a NVSTATE
transition to OPEN is triggered (erasing the whole user flash memory).

 

It is not clear what NVSTATE is in this context. Is this a left-over from documentation of a different MCU?

 

I don’t think it is PRODUCT_STATE. Because to my understanding you can have a PRODUCT_STATE > OPEN and not enable TrustZone and then write to FLASH_WRP1R_PRG to turn off write protection - you should be able to do a bank erase on bank 1. You can set initial values with an OB but I can’t see any documentation that this also makes changing FLASH_WRP1R_PRG illegal and the relevant OBs are not protected by PRODUCT_STATE the same way as e.g. SECWM and HDP.

Same reasoning for flash bank 2.

And if you enable TrustZone, it is stated that FLASH_WRP[1, 2]R_PRG is non-secure. So as long as you don’t set part of the flash to secure watermarked, bank erase should work.

Also note that a AFAIK a regression of PRODUCT_STATE do not restore the WRP OBs to their default state.

 

The only other place NVSTATE is mentioned in RM0481 is in Table 507 TAMP interconnection:

tamp_itamp6     JTAG/SWD access when NVSTATE ? OPEN

 

Here, “NVSATE” should be “PRODUCT_STATE”?

 

  Best regards, Jesper

 

[Pavel A.]

Non-volatile ?

[Ozone]

I would think so, too.

The abbreviation NVM for any memory technology retaining it’s state during power-off is very common in the industry.

I don’t know the H5 reference manual in any detail, but I would start with searching the whole document for said term. Perhaps the name of a bit in some peripheral config or status register.

[JesperEC]

I don’t know the H5 reference manual in any detail, but I would start with searching the whole document for said term.

 

Already done. There are exactly 2 occurrences and both of them are listed in my post. 😎 

It is possible that the text exists in some bitmap image as well and then can’t be found by a standard pdf-viewer, but I consider that unlikely.

 

I think this needs to be addressed by someone from ST and I presume they need to correct the document.

 

    Best regards, Jesper