Rev. 1.10
78
November 26, 2019
Rev. 1.10
79
November 26, 2019
HT68FB240
USB Low Speed Flash MCU
SIMD Register
Bit
7
6
5
4
3
2
1
0
Name
D7
D6
D5
D4
D3
D2
D1
D0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
x
x
x
x
x
x
x
x
"x" unknown
There are also three control registers for the SPI interface, SIMC0,
SIMC2 and SBSC
. Note that the
SIMC2 register also has the name SIMA which is used by the I
2
C function. The SIMC1 register is
not used by the SPI function, only by the I
2
C function. Register SIMC0 is used to control the enable/
disable function and to set the data transmission clock frequency. Although not connected with the
SPI function, the SIMC0 register is also used to control the Peripheral Clock Prescaler. Register
SIMC2 is used for other control functions such as LSB/MSB selection, write collision flag etc.
SIMC0 Register
Bit
7
6
5
4
3
2
1
0
Name
SIM2
SIM1
SIM0
PCKEN
PCKP1
PCKP0
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
SIM2~SIM0:
SIM Operating Mode Control
000: SPI master mode; SPI clock is f
SYS
/4
001: SPI master mode; SPI clock is f
SYS
/16
010: SPI master mode; SPI clock is f
SYS
/64
011: SPI master mode; SPI clock is
f
LIRC
100: SPI master mode; SPI clock is TM0 CCRP match frequency/2
101: SPI slave mode
110: I
2
C slave mode
111: I/O mode
These bits setup the overall operating mode of the SIM function. As well as selecting
if the I
2
C or SPI function, they are used to control the SPI Master/Slave selection and
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
SYS
01: f
SYS
/4
10: f
SYS
/8
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. If the SIM is configured to operate as an SPI interface via the SIM2~SIM0
bits, the contents of the SPI control registers will remain at the previous settings when
the SIMEN bit changes from low to high and should therefore be first initialised by
the application program. If the SIM is configured to operate as an I
2
C interface via the