Datasheet

STM8S105xx
Option bytes
Option
byte no.
Description
PRSC[1:0] AWU clock prescaler
0x: 16 MHz to 128 kHz prescaler
10: 8 MHz to 128 kHz prescaler
11: 4 MHz to 128 kHz prescaler
OPT5
HSECNT[7:0]:HSE crystal oscillator stabilization time
0x00: 2048 HSE cycles
0xB4: 128 HSE cycles
0xD2: 8 HSE cycles
0xE1: 0.5 HSE cycles
OPT6 Reserved
OPT7 Reserved
OPTBL
BL[7:0] Bootloader option byte
For STM8S products, this option is checked by the boot ROM code after reset.
Depending on the content of addresses 0x487E, 0x487F, and 0x8000 (reset vector), the
CPU jumps to the bootloader or to the reset vector. Refer to the UM0560 (STM8L/S
bootloader manual) for more details.
For STM8L products, the bootloader option bytes are on addresses 0xXXXX and
0xXXXX+1 (2 bytes). These option bytes control whether the bootloader is active or not.
For more details, refer to the UM0560 (STM8L/S bootloader manual) for more details.
Table 14: Description of alternate function remapping bits [7:0] of OPT2
Option
byte no.
Description
(1)
OPT2
AFR7 Alternate function remapping option 7
0: AFR7 remapping option inactive: Default alternate function
(2)
.
1: Port D4 alternate function = BEEP.
AFR6 Alternate function remapping option 6
0: AFR6 remapping option inactive: Default alternate functions
(2)
.
1: Port B5 alternate function = I
2
C_SDA; port B4 alternate function = I
2
C_SCL.
AFR5 Alternate function remapping option 5
0: AFR5 remapping option inactive: Default alternate functions
(2)
.
1: Port B3 alternate function = TIM1_ETR; port B2 alternate function = TIM1_NCC3;
port B1 alternate function = TIM1_CH2N; port B0 alternate function = TIM1_CH1N.
AFR4 Alternate function remapping option 4
0: AFR4 remapping option inactive: Default alternate function
(2)
.
1: Port D7 alternate function = TIM1_CH4.
AFR3 Alternate function remapping option 3
0: AFR3 remapping option inactive: Default alternate function
(2)
.
1: Port D0 alternate function = TIM1_BKIN.
AFR2 Alternate function remapping option 2
0: AFR2 remapping option inactive: Default alternate function
(2)
.
1: Port D0 alternate function = CLK_CCO. Note: AFR2 option has priority over AFR3 if
both are activated.
AFR1 Alternate function remapping option 1
0: AFR1 remapping option inactive: Default alternate functions
(2)
.
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