
Rev. 1.20
�0
��to�e� 0�� 201�
Rev. 1.20
�1
��to�e� 0�� 201�
HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
HT69F30A/HT69F40A/HT69F50A
TinyPower
TM
I/O Flash 8-Bit MCU with LCD & EEPROM
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~PHPU, and are implemented using weak
PMOS transistors.
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.
I/O Port Control Registers
Each Port has its own control register, known as PAC~PHC, which controls the input/output
configuration. With this control register, each I/O pin with or without pull-high resistors can be
reconfigured dynamically under software control. For the I/O pin to function as an input, the
corresponding bit of the control register must be written as a “1”. This will then allow the logic state
of the input pin to be directly read by instructions. When the corresponding bit of the control register
is written as a “0”, the I/O pin will be setup as a CMOS output. If the pin is currently setup as an
output, instructions can still be used to read the output register.
However, it should be noted that the program will in fact only read the status of the output data latch
and not the actual logic status of the output pin.
Pin-shared Functions
The flexibility of the microcontroller range is greatly enhanced by the use of pins that have more
than one function. Limited numbers of pins can force serious design constraints on designers but by
supplying pins with multi-functions, many of these difficulties can be overcome. For these pins, the
chosen function of the multi-function I/O pins is selected by a series of regiters via the application
program control.