Rev. 1.10
56
November 26, 2019
Rev. 1.10
57
November 26, 2019
HT68FB240
USB Low Speed 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~PE. 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.
I/O Register List
Register
Name
Bit
7
6
5
4
3
2
1
0
PAWU
PAWU7
PAWU6
PAWU5
PAWU4
PAWU3
PAWU2
PAWU1
PAWU0
PAPU
PAPU7
PAPU6
PAPU5
PAPU4
PAPU3
PAPU2
PAPU1
PAPU0
PA
PA7
PA6
PA5
PA4
PA3
PA2
PA1
PA0
PAC
PAC7
PAC6
PAC5
PAC4
PAC3
PAC2
PAC1
PAC0
PXWU
—
PELWU
PDHWU PDLWU PCHWU PCLWU
PBHWU
PBLWU
PXPU
—
PELPU
PDHPU
PDLPU
PCHPU
PCLPU
PBHPU
PBLPU
PB
PB7
PB6
PB5
PB4
PB3
PB2
PB1
PB0
PBC
PBC7
PBC6
PBC5
PBC4
PBC3
PBC2
PBC1
PBC0
PC
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
PCC
PCC7
PCC6
PCC5
PCC4
PCC3
PCC2
PCC1
PCC0
PD
PD7
PD6
PD5
PD4
PD3
PD2
PD1
PD0
PDC
PDC7
PDC6
PDC5
PDC4
PDC3
PDC2
PDC1
PDC0
PE
—
—
—
—
—
—
PE1
PE0
PEC
—
—
—
—
—
—
PEC1
PEC0
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 PAPU
and PXPU, and are implemented using weak
PMOS transistors.
PAPU Register
Bit
7
6
5
4
3
2
1
0
Name
PAPU7
PAPU6
PAPU5
PAPU4
PAPU3
PAPU2
PAPU1
PAPU0
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
PAPU7~PAPU0:
Port A bit 7 ~ bit 0 Pull-high Control
0: Disable
1: Enable