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Nations Technologies Inc.
Tel
：
+86-755-86309900
：
Address: Nations Tower, #109 Baoshen Road, Hi-tech Park North.
Nanshan District, Shenzhen, 518057, P.R.China
After each system reset, the option byte data is read out from the option byte block of Flash and stored in the option
byte register (FLASH_OB/FLASH_WRP) with read-only property. At the same time, the option byte complement
data read out together will be used to verify whether the option byte data is correct. If it does not match, an option
byte error flag (FLASH_OB.OBERR) will be generated. When an option byte error occurs, the corresponding option
byte is forced to 0xFF. When the option byte and its complement are both 0xFF (the state after erasing), the above
verification steps are skipped and verification is not required.
Table 3-3 Option byte list
Address
[31:24]
Corresponding
complement code
[23:16]
Option byte
[15:8]
Corresponding
complement code
[7:0]
Option byte
0x1FFF_F800
nUSER
USER
nRDP1
RDP1
0x1FFF_F804
nData1
Data1
nData0
Data0
0x1FFF_F808
nWRP1
WRP1
nWRP0
WRP0
0x1FFF_F80C
nWRP3
WRP3
nWRP2
WRP2
0x1FFF_F810
-
-
nRDP2
RDP2
Read protection L1 level option byte: RDP1
Protect the code stored in the flash memory;
When the correct value is written, it will be forbidden to read the flash memory;
The result of whether RDP1 is turned on or not can be inquired through FLASH_OB[1];
User configuration options: USER
USER[7:3]
：
Reserved
USER[2]
：
nRST_STDBY configuration options, read through FLASH_OB [4]
0
：
Reset when entering standby mode
1
：
No reset occurs when entering standby mode
USER[1]
：
nRST_STOP, read through FLASH_OB[3]
0
：
Reset occurs when entering stop0/stop2 mode
1
：
No reset occurs when entering stop0/stop2 mode
USER[0]
：
WDG_SW configuration options, read through FLASH_OB [2]
0
：
Hardware watchdog
1
：
Software watchdog
2 bytes of user data: Datax
Data1 (stored in FLASH_OB[25:18]);
Data0 (stored in FLASH_OB [17:10]);
Write protection option byte: WRP0 ~ 3, which can be written through the register FLASH _WRP [31:0] query
