HT68F03 datasheet(48/139 Pages) HOLTEK

48 / 139 page

HT66F03/HT66F04/HT68F03/HT68F04

Rev. 1.00

April 16, 2010

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. 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

²MOV A,[m]², where m denotes the port address. For output opera-

tion, all the data is latched and remains unchanged until the output latch is rewritten.

· I/O Register List

Name

Bit

76543210

PAWU

PAPU

PAC

Pull-high Resistors

Many product applications require pull-high resistors for their switch inputs usually requiring the use of an external re-

sistor. 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 the register PAPU, and

are implemented using weak PMOS transistors.

· PAPU Register

Bit

76543210

Name

R/W

POR

00000000

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.

· PAWU Register

Bit

76543210

Name

R/W

POR

00000000

Bit 7~0

PAWU: Port A bit 7 ~ bit 0 Wake-up Control

0: Disable

1: Enable

HT68F03 Datasheet(PDF) 48 Page - Holtek Semiconductor Inc

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