Option byte description
RM0365
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DocID025202 Rev 7
Table 13. Description of the option bytes
Flash memory
address
Option bytes
0x1FFF F800
Bits [31:24]:
nUSER
Bits [23:16]:
USER:
User option byte (stored in FLASH_OBR[15:8])
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
Bit 23: Reserved
Bit 22:
SRAM_PE
(not available in STM32F302x6/8 devices)
The SRAM hardware parity check is disabled by default. This bit allows the user to
enable the SRAM hardware parity check.
0: Parity check enabled.
1: Parity check disabled.
Bit 21:
VDDA_MONITOR
This bit selects the analog monitoring on the VDDA power source:
0: VDDA power supply supervisor disabled.
1: VDDA power supply supervisor enabled.
Bit 20:
nBOOT1
Together with the BOOT0 pin, this bit selects Boot mode from the main Flash
memory, SRAM or System memory. Refer to
Bit 19: Reserved, must be kept at reset.
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 value of this byte defines the Flash memory protection level
0xAA: Level 0
0xXX (except 0xAA and 0xCC): Level 1
0xCC: Level 2
The protection levels are stored in the Flash_OBR Flash option bytes register
(RDPRT bits).
0x1FFF F804
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[31:24])
Bits [15:8]:
nData0
Bits [7:0]:
Data0
(stored in FLASH_OBR[23:16])