DocID018909 Rev 11
107/1731
RM0090
Embedded Flash memory interface
112
Bits 31:28 Reserved, must be kept cleared.
Bits 27:16
nWRP[11:0]:
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 on selected sector
1: Write protection inactive on selected sector
Bits 15:8
RDP[7:0]:
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[2:0]:
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. Always read as “0”.
Bits 3:2
BOR_LEV[1:0]:
BOR reset Level
These bits contain the supply level threshold that activates/releases the reset. They can be
written to program a new BOR level. By default, BOR is off. When the supply voltage (V
DD
)
drops below the selected BOR level, a device reset is generated.
00: BOR Level 3 (VBOR3), brownout threshold level 3
01: BOR Level 2 (VBOR2), brownout threshold level 2
10: BOR Level 1 (VBOR1), brownout threshold level 1
11: BOR off, 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.