How to access the 2KB user option bytes in H7

[Dan4]

In the STM32H7 datasheets, page 23 (H750) or 26 (H743) - ST says the device has 2KB user option bytes flash area.

Does anyone have idea if this is a typo? Or how to access this memory?

If it really is there - it has a good potential to be used as config flash, because it seems independently erasable from the main flash sectors.

[PMath.4]

This any help?

https://community.st.com/s/question/0D50X00009XkfPk/simple-example-program-to-read-and-write-option-bytes-on-stm32f042k6-using-hal-libraries

[Dan4]

Thanks @PMath.4, but the problem is that these functions (used in the link) are not available in the flash_ex HAL files for H7, there are no similar defines in e.g. stm32h7??xx.h, and there is nothing in the reference manual explaining how to access these registers.

I would normally expect that the option bytes (as usual) are not directly mapped on the memory bus but are indirectly accessed via registers (which technically are again accessed via the memory bus, but this is a just a detail).

[loeffel2]

Hi Dan

I am also looking for a possibility to use the 2k user option bytes of the stm32h7 devices. But I am not sure if these so called user options bytes could be freely used or not. Did you figure out how the user options bytes could be accessed and programmed?

Best regards

Raphael

[Uwe Bonnes]

Are there really 2 k of user option bytes beside the user option bits fr configuration? I do not see it mentioned in the reference manual. I do not find in in the memory map neither.

[loeffel2]

Dear Uwe

This is the reason I am confused about the user options topic. The data sheet talks about 2k user options but the ref manual dosen't as you mentioned.

[Andreas Bolsch]

That's a recurring topic, e.g. https://community.st.com/s/question/0D53W00000mm98USAQ/how-to-write-nonreserved-option-bytes-on-stm32h750xx-mcu

[loeffel2]

Thanks for the link and clarification of the topic. I will use the first sector of internal flash bank 2 as a kind of OTP replacement.

[DanNew]

@loeffel2​ - Unfortunately I have not found a way to use this 2KB area. My contacts in ST were not aware either. It would have been convenient with the Value line devices...