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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Pull-high Resistors
Many product applications require pull-high resistors for their switch inputs usually requiring the
use of an external resistor. To eliminate the need for these external resistors, all I/O pins, when
configured as an input have the capability of being connected to an internal pull-high resistor. These
pull-high resistors are selected using registers, namely PAPU~PDPU, and are implemented using
weak PMOS transistors.
Note that the pull-high resistor can be controlled by the relevant pull-high control register only
when the pin-shared functional pin is selected as an input or NMOS output. Otherwise, the pull-high
resistors cannot be enabled.
PxPU Register
Bit
7
6
5
4
3
2
1
0
Name
PxPU�
PxPU6
PxPU5
PxPU4
PxPU3
PxPU�
PxPU1
PxPU0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
PxPUn
: I/O Port x Pin pull-high function control
0: Disable
1: Enable
The PxPUn bit is used to control the pin pull-high function. Here the "x"can be A, B, C and D.
However, the actual available bits for each I/O Port may be different.
Port A Wake-up
The HALT instruction forces the microcontroller into the SLEEP or IDLE Mode which preserves
power, a feature that is important for battery and other low-power applications. Various methods
exist to wake-up the microcontroller, one of which is to change the logic condition on one of the Port
A pins from high to low. This function is especially suitable for applications that can be woken up
via external switches. Each pin on Port A can be selected individually to have this wake-up feature
using the PAWU register.
Note that the wake-up function can be controlled by the wake-up control registers only when the
pin-shared functional pin is selected as general purpose input/output and the MCU enters the power
down mode.
PAWU Register
Bit
7
6
5
4
3
2
1
0
Name
PAWU�
PAWU6
PAWU5
PAWU4
PAWU3
PAWU�
PAWU1
PAWU0
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
Bit 7~0
PAWU7~PAWU0
: PA7~PA0 wake-up function control
0: Disable
1: Enable