OTP size for STM32F746XX

grmpyc8 · ‎2022-11-07

I found a strange mismatch in the reference manual for the OTP memory size:

Accordingly to the manual page 78 (https://www.st.com/resource/en/reference_manual/rm0385-stm32f75xxx-and-stm32f74xxx-advanced-armbased-32bit-mcus-stmicroelectronics.pdf) the start-address of the OTP memory begins at `0x1FF0 F000` and ends at address: `0x1FF0 F41F` (in AXIM mode) and is declared as a memory area with the size of 1024 bytes.

But if I calculate `0x1FF0F41F - 0x1FF0F000 + 1` I get a total of 1056 bytes OTP memory?!

Is this a typo in the manual or is my calculation wrong?

Piranha · ‎2022-11-07

The "sector size" seems to show how many useful bytes there are (1024), not the whole address range (1056). But then for option bytes there are just 8 useful bytes, laid out like 16 bytes of registers and taking 32 bytes of address range. And for system memory 60 KB is just rounded value. More consistency would be nice.

Also the title of the "Bloc base address on AXIM interface" column has a spelling error - should be "Block". And it's not only the base address, but an address range.

Most likely the same is true for other reference manuals.

View solution in original post

Andreas Bolsch · ‎2022-11-07

RM0385, section 3.6.

Piranha · ‎2022-11-07

The "sector size" seems to show how many useful bytes there are (1024), not the whole address range (1056). But then for option bytes there are just 8 useful bytes, laid out like 16 bytes of registers and taking 32 bytes of address range. And for system memory 60 KB is just rounded value. More consistency would be nice.

Also the title of the "Bloc base address on AXIM interface" column has a spelling error - should be "Block". And it's not only the base address, but an address range.

Most likely the same is true for other reference manuals.

grmpyc8 · ‎2022-11-07

Thank you very much for the quick help!