
Rev. 1.20
56
November 20, 2019
Rev. 1.20
57
November 20, 2019
HT66F2740
12V High Current Flash MCU
HT66F2740
12V High Current Flash MCU
Input/Output Ports
Holtek microcontrollers offer considerable flexibility on their I/O ports. With the input or output
designation of every pin fully under user program control, pull-high selections for all ports and
wake-up selections on certain pins, the user is provided with an I/O structure to meet the needs of a
wide range of application possibilities.
The device provides bidirectional input/output lines labeled with port names PA and PD. These I/O
ports are mapped to the RAM Data Memory with specific addresses as shown in the Special Purpose
Data Memory table. All of these I/O ports can be used for input and output operations. For input
operation, these ports are non-latching, which means the inputs must be ready at the T2 rising edge
of instruction “MOV A, [m]”, where m denotes the port address. For output operation, all the data is
latched and remains unchanged until the output latch is rewritten.
Register
Name
Bit
7
6
5
4
3
2
1
0
PA
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
PAC
PAC7
PAC6
PAC5
PAC4
PAC3
PAC2
PAC1
PAC0
PAPU
PAPU7
PAPU6
PAPU5
PAPU4
PAPU3
PAPU2
PAPU1
PAPU0
PAWU
PAWU7
PAWU6
PAWU5
PAWU4
PAWU3
PAWU2
PAWU1
PAWU0
PD
—
—
PD5
PD4
PD3
PD2
PD1
PD0
PDC
—
—
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
PDPU
—
—
PDPU5
PDPU4
PDPU3
PDPU2
PDPU1
PDPU0
“—”: Unimplemented, read as “0”
I/O Logic Function Register List
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 a
digital input have the capability of being connected to an internal pull-high resistor.
These pull-high resistors are selected using registers, namely PAPU and 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 a digital input or NMOS output. Otherwise, the pull-high
resistors cannot be enabled.
• PxPU Register
Bit
7
6
5
4
3
2
1
0
Name
PxPU7
PxPU6
PxPU5
PxPU4
PxPU3
PxPU2
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 or D.
However, the actual available bits for each I/O Port may be different.