DocID15687 Rev 5

25/29

PM0059

Flash memory interface

28

Bits 31:28 Reserved, must be kept cleared.

Bits 27:16 nWRP: Not write protect

These bits contain the value of the write-protection option bytes after reset. They can be

written to program a new write protect value into Flash memory.

0: Write protection active

1: Write protection not active

Bits 15:8 RDP: Read protect

These bits contain the value of the read-protection option level after reset. They can be

written to program a new read protection value into Flash memory.

0xAA: Level 0, read protection not active

0xCC: Level 2, chip read protection active

Others: Level 1, read protection of memories active

Bits 7:5 USER: User option bytes

These bits contain the value of the user option byte after reset. They can be written to

program a new user option byte value into Flash memory.

Bit 7: nRST_STDBY

Bit 6: nRST_STOP

Bit 5: WDG_SW

Note: When changing the WDG mode from hardware to software or from software to

hardware, a system reset is required to make the change effective.

Bit 4 Reserved, must be kept cleared.

Bits 3:2 BOR_LEV: BOR reset Level

These bits contain the supply level threshold that activates/releases the reset. They can be

drops below the selected BOR level, a device reset is generated.

00: BOR Level 3 (VBOR3), reset threshold level 3

01: BOR Level 2 (VBOR2), reset threshold level 2

10: BOR Level 1 (VBOR1), reset threshold level 1

11: BOR off (VBOR0), POR/PDR reset threshold level is applied.

Note: For full details about BOR characteristics, refer to the “Electrical characteristics” section

in the device datasheet.

Bit 1 OPTSTRT: Option start

This bit triggers a user option operation when set. It is set only by software and cleared when

the BSY bit is cleared.

Bit 0 OPTLOCK: Option lock

Write to 1 only. When this bit is set, it indicates that the FLASH_OPTCR register is locked.

This bit is cleared by hardware after detecting the unlock sequence.

In the event of an unsuccessful unlock operation, this bit remains set until the next reset.