BS85B12-3_12 Datasheet, PDF (136/183 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3/BS85C20-5
Touch Key Flash MCU with LCD/LED Driver
Peripheral Clock Output
The Peripheral Clock Output allows the device to supply external hardware with a clock signal
synchronised to the microcontroller clock.
Peripheral Clock Operation
As the peripheral clock output pin, PCK, is shared with I/O line, the required pin function is chosen
via PCKEN in the SIMC0 register. The Peripheral Clock function is controlled using the SIMC0
register. The clock source for the Peripheral Clock Output can originate from either the TM0 CCRP
match frequency/2 or a divided ratio of the internal fSYS clock. The PCKEN bit in the SIMC0 register
is the overall on/off control, setting PCKEN bit to "1" enables the Peripheral Clock, setting PCKEN
bit to "0" disables it. The required division ratio of the system clock is selected using the PCKP1
and PCKP0 bits in the same register. If the device enters the SLEEP Mode this will disable the
Peripheral Clock output.
SIMC0 Register
Bit
7
6
5
4
3
2
1
0
Name
SIM2
SIM1
SIM0 PCKEN PCKPSC1 PCKPSC0 SIMEN
—
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
—
POR
1
1
1
0
0
0
0
—
Bit 7~5
Bit 4
Bit 3~2
Bit 1
Bit 0
SIM2~SIM0: SIM Operating Mode Control
Described elsewhere
PCKEN: PCK Output Pin Control
0: disable
1: enable
PCKPSC1, PCKPSC0: Select PCK output pin frequency
0: fSYS
1: fSYS/4
2: fSYS/8
3: TM0 CCRP match frequency/2
SIMEN: SIM Control
Described elsewhere
Unimplemented, read as "0"
Rev. 1.20
136
August 10, 2012