Table 7. Option Byte Organization; Table 8. Description Of The Option Bytes - ST STM32F101xx series Programming Manual

Reading/programming the embedded Flash memory
Table 7.
Address
0x1FFF F800
0x1FFF F804
0x1FFF F808
0x1FFF F80C
Table 8.
Flash memory
address
0x1FFF F800
0x1FFF F804
0x1FFF F808
20/31
Option byte organization
[31:24]
nUSER
nData1
nWRP1
nWRP3
Description of the option bytes
Bits [31:24] nUSER
Bits [23:16] USER: User option byte (stored in FLASH_OBR[9:2])
This byte is used to configure the following features:
– Select the watchdog event: Hardware or software.
– Reset event when entering Stop mode.
– Reset event when entering Standby mode.
Note: Only bits [16:18] are used, bits [23:19]: 0x1F are not used.
Bit 18: nRST_STDBY
0: Reset generated when entering Standby mode.
1: No reset generated.
Bit 17: nRST_STOP
0: Reset generated when entering Stop mode
1: No reset generated
Bit 16: WDG_SW
0: Hardware watchdog
1: Software watchdog
Bits [15:8]: nRDP
Bits [7:0]: RDP: Read protection option byte
The read protection helps the user protect the software code stored in Flash
memory. It is activated by setting the RDP option byte.
When this option byte is programmed to a correct value (RDPRT key = 0x00A5),
read access to the Flash memory is allowed.
(The result of RDP level enabled/disabled is stored in FLASH_OBR[1].)
Datax: Two bytes for user data storage.
These addresses can be programmed using the option byte programming
procedure.
Bits [31:24]: nData1
Bits [23:16]: Data1 (stored in FLASH_OBR[25:18])
Bits [15:8]: nData0
Bits [7:0]: Data0 (stored in FLASH_OBR[17:10])
WRPx: Flash memory write protection option bytes
Bits [31:24]: nWRP1
Bits [23:16]: WRP1 (stored in FLASH_WRPR[15:8])
Bits [15:8]: nWRP0
Bits [7:0]: WRP0 (stored in FLASH_WRPR[7:0])
Doc ID 17863 Rev 1
[23:16] [15:8]
USER nRDP
Data1 nData0
WRP1 nWRP0
WRP3 nWRP2
Option bytes
PM0075
[7:0]
RDP
Data0
WRP0
WRP2