Peripheral Clock Output - Holtek HT66F20-1 Manual

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 f
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
�a�e SIM�
R/W R/W
POR 1
Bit 7~5 SIM2, SIM1, SIM0: SIM operating mode control
000: SPI master mode; SPI clock is f
001: SPI master mode; SPI clock is f
010: SPI master mode; SPI clock is f
011: SPI master mode; SPI clock is f
100: SPI master mode; SPI clock is TM0 CCRP match frequency/2
101: SPI slave mode
110: I
111: Unused mode
These bits setup the overall operating mode of the SIM function. As well as selecting
if the I
the SPI Master clock frequency. The SPI clock is a function of the system clock but
can also be chosen to be sourced from the TM0. If the SPI Slave Mode is selected then
the clock will be supplied by an external Master device.
Bit 4 PCKEN: PCK output pin control
0: Disable
1: Enable
Bit 3~2 PCKP1, PCKP0: select PCK output pin frequency
00: f
01: f
10: f
11: TM0 CCRP match frequency/2
Bit 1 SIMEN: SIM control
0: Disable
1: Enable
The bit is the overall on/off control for the SIM interface. When the SIMEN bit is
cleared to zero to disable the SIM interface, the SDI, SDO, SCK and SCS, or SDA
and SCL lines will be in a floating condition and the SIM operating current will be
reduced to a minimum value. When the bit is high the SIM interface is enabled. The
SIM configuration option must have first enabled the SIM interface for this bit to be
effective. Note that when the SIMEN bit changes from low to high the contents of the
SPI control registers will be in an unknown condition and should therefore be first
initialised by the application program.
Bit 0 unimplemented, read as "0"
Rev. 1.40
HT66F20-1/HT66F30-1/HT68F20-1/HT68F30-1
clock. The PCKEN bit in the SIMC0 register is the
SYS
6 5 4
SIM1 SIM0 PCKE�
R/W R/W R/W
1 1 0
C slave mode
2
C or SPI function, they are used to control the SPI Master/Slave selection and
2
SYS
/4
SYS
/8
SYS
1�0
Flash MCU with EEPROM
3 2
PCKP1 PCKP0 SIME�
R/W R/W R/W
0 0
/4
SYS
/16
SYS
/64
SYS
TBC
�ove��e� ��� �01�
1 0
—
—
0 —