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'F303 write protection, how does it work?

waclawek.jan
Super User

Reading Embedded Flash memory chapter of RM0316 and can't grab how the write protection is supposed to work.

a) 4.3.2 Write protection says:

It is activated by configuring the WRP[1:0] option bytes

Each other instances where WRP is mentioned says i'ts either WRP[3:0} or, in FLASH_WRPR register description, it's 32 bits, so I guess [1:0] a typo.

b) Okay so we have 32 bits for write protection, and 4.3.2 Write protection says

The write protection is implemented with a granularity of 2 pages.

According to 4.2.1 Flash memory organization:

The memory organization is based on a main memory block containing 128 pages of

2 Kbytes in STM32F303xB/C and STM32F358xC devices, 256 pages of 2 Kbytes in the

STM32F303xD/E

How exactly do 32 bits describe protection of 128 pages (let alone 256 pages), 2 pages per bit?

Thanks,

JW

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1 ACCEPTED SOLUTION

Accepted Solutions
Andreas Bolsch
Lead II

It's somewhat ... weird, I'd say. see table 14 in section in section 5 of the RM. WRP0 to WRP3 refers to the four bytes in FLASH_WRPR.

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2 REPLIES 2
Andreas Bolsch
Lead II

It's somewhat ... weird, I'd say. see table 14 in section in section 5 of the RM. WRP0 to WRP3 refers to the four bytes in FLASH_WRPR.

waclawek.jan
Super User

Thanks for the pointer, Andreas.

Well, OK, so bit 31 (or bit 7 of byte 3) does not cover 2 pages but 64+2 in 'B/C and 192+2 in 'D/E.

Why doesn't the chapter aptly named Write protection (4.3.2) say so?

JW

@Imen DAHMEN​