VECT_TAB_OFFSET comments in different releases

[escherstair]

In file system_stm32h7xx.c the macro VECT_TAB_OFFSET is defined in different ways under several conditions. This is ok. But I see a comments on these definition, that changes from release to release, and I don't understand why. You can see it blaming the file system_stm32h7xx.c. In release 1.9.1 it was

#define VECT_TAB_OFFSET         0x00000000U       /*!< Vector Table base offset field.
                                                       This value must be a multiple of 0x200. */

note the value 0x200 In release 1.10.0 it was

#define VECT_TAB_OFFSET         0x00000000U       /*!< Vector Table base offset field.
                                                       This value must be a multiple of 0x300. */

note that now the value is 0x300 In release 1.11.0 it is

#define VECT_TAB_OFFSET         0x00000000U       /*!< Vector Table base offset field.
                                                       This value must be a multiple of 0x400. */

note the value 0x400

I dont' understand the reason for this change. Similar changes in the comment can be seen for VECT_TAB_BASE_ADDRESS

I need to relocate the vector table, and so I must be sure which is the allowed values. And most importan idf they change with releases on the firmware. I have an application developed with 1.9.1 and my offset is a multiple of 0x200 (but not a multiple of 0x400) Should I change it to a different value (multiple of 0x400) if I migrate my project to firmware 1.11.0?

[TOUNSTM]

Hello @escherstair,

Thank you for this report. We will get back to you as soon as we analyze it further. This may take some time. Thank you for your comprehension.

With Regards,

[carlo-dev-git]

Please check this too https://github.com/STMicroelectronics/cmsis_device_h7/issues/2

[ALABSTM]

Hi,

@escherstair, the offset multiple to consider is 0x400 indeed. As suggested by @carlo-dev-git, the confirmation can be found in issue cmsis_device_h7#2.

The rationale is that the vector table offset shall:

• be a multiple of its total size in bytes rounded to the nearest power of 2,
• comply to the constraint that bits 0 to 8 of the VTOR register are reserved, thus shall be left to zero.

As for STM32H7, we have 162 lines + 16 exceptions = (162 + 16) x 4 = 0x2C8 --> rounded to 0x400.

You may find further details in the programmers manual, revision 5, page 197, paragraph 4.3.4.

I hope this answers your question. Please allow me to close this thread.

PS: @carlo-dev-git, thank you very much for you helpful reply.