Datasheet

Option bytes
STM8S105xx
Addr. Option
name
Option
byte no.
Option bits Factory
default
setting
7 6 5 4 3 2 1 0
0x487F NOPTBL NBL[7:0]
Table 13: Option byte description
Option
byte no.
Description
OPT0
ROP[7:0] Memory readout protection (ROP)
AAh: Enable readout protection (write access via SWIM protocol)
Note: Refer to the family reference manual (RM0016) section on Flash/EEPROM
memory readout protection for details.
OPT1
UBC[7:0] User boot code area
0x00: no UBC, no write-protection
0x01: Page 0 to 1 defined as UBC, memory write-protected
0x02: Page 0 to 3 defined as UBC, memory write-protected
0x03: Page 0 to 4 defined as UBC, memory write-protected
...
0x3E: Pages 0 to 63 defined as UBC, memory write-protected
Other values: Reserved
Note: Refer to the family reference manual (RM0016) section on Flash write protection
for more details.
OPT2
AFR[7:0]
Refer to following table for the alternate function remapping decriptions of bits [7:2].
OPT3
HSITRIM:High speed internal clock trimming register size
0: 3-bit trimming supported in CLK_HSITRIMR register
1: 4-bit trimming supported in CLK_HSITRIMR register
LSI_EN:Low speed internal clock enable
0: LSI clock is not available as CPU clock source
1: LSI clock is available as CPU clock source
IWDG_HW: Independent watchdog
0: IWDG Independent watchdog activated by software
1: IWDG Independent watchdog activated by hardware
WWDG_HW: Window watchdog activation
0: WWDG window watchdog activated by software
1: WWDG window watchdog activated by hardware
WWDG_HALT: Window watchdog reset on halt
0: No reset generated on halt if WWDG active
1: Reset generated on halt if WWDG active
OPT4
EXTCLK: External clock selection
0: External crystal connected to OSCIN/OSCOUT
1: External clock signal on OSCIN
CKAWUSEL:Auto wake-up unit/clock
0: LSI clock source selected for AWU
1: HSE clock with prescaler selected as clock source for for AWU
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