RM0377 Datasheet, PDF (104/862 Pages) STMicroelectronics – This reference manual targets application developers

RM0377
Flash program memory and data EEPROM (FLASH)
3.7.6
Option bytes unlock key register (FLASH_OPTKEYR)
Address offset: 0x14
Reset value: 0x0000 0000
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FLASH_OPTKEYR[31:16]
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FLASH_OPTKEYR[15:0]
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
w
Bits 31:0 This is a write-only register. With a sequence of two write operations (the first one with
0xFBEAD9C8 and the second one with 0x24252627), the write size being that of a word, it is
possible to unlock the Option bytes area and the OBL_LAUNCH bit. The sequence can only be
executed when PELOCK is already unlocked. For more details, refer to Unlocking the Option
bytes area.
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