HT46R068B/HT46R069B
Enhanced A/D Type 8-bit OTP MCU
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 some pins,
the chosen function of the multi-function I/O pins is set by configuration options while for others
the function is set by application program control.
External Interrupt Input
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The external interrupt pin, INT, is pin-shared with an I/O pin. To use the pin as an external
interrupt input the correct bits in the INTC0 register must be programmed. The pin must also be
setup as an input by setting the PAC3 bit in the Port Control Register. A pull-high resistor can
also be selected via the appropriate port pull-high resistor register. Note that even if the pin is
setup as an external interrupt input the I/O function still remains.
External Timer/Event Counter Input
The Timer/Event Counter pins, TC0, TC1 and TC2 are pin-shared with I/O pins. For these
shared pins to be used as Timer/Event Counter inputs, the Timer/Event Counter must be
configured to be in the Event Counter or Pulse Width Capture Mode. This is achieved by setting
the appropriate bits in the Timer/Event Counter Control Register. The pins must also be setup
as inputs by setting the appropriate bit in the Port Control Register. Pull-high resistor options
can also be selected using the port pull-high resistor registers. Note that even if the pin is setup
as an external timer input the I/O function still remains.
PFD Output
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The PFD function output is pin-shared with an I/O pin. The output function of this pin is chosen
using the CTRL0 register. Note that the corresponding bit of the port control register, must
setup the pin as an output to enable the PFD output. If the port control register has setup the pin
as an input, then the pin will function as a normal logic input with the usual pull-high selection,
even if the PFD function has been selected.
PWM Outputs
The PWM function whose outputs are pin-shared with I/O pins. The PWM output functions
are chosen using the CTRL0 and CTRL2 registers. Note that the corresponding bit of the port
control registers, for the output pin, must setup the pin as an output to enable the PWM output. If
the pins are setup as inputs, then the pin will function as a normal logic input with the usual pull-
high selections, even if the PWM registers have enabled the PWM function.
SCOM Driver Pinss
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Pins PB0~PB3 on Port B can be used as LCD COM driver pins. This function is controlled
using the SCOMC register which will generate the necessary 1/2 bias signals on these four pins.
A/D Inputs
Each device in this series has up to 16 inputs to the A/D converter. All of these analog inputs are
pin-shared with I/O pins. If these pins are to be used as A/D inputs and not as I/O pins then the
corresponding PCRn bits in the ANCSR0 and ANCSR1 registers, must be properly setup. There
are no configuration options associated with the A/D converter. If chosen as I/O pins, then full
pull-high resistor configuration options remain, however if used as A/D inputs then any pull-high
resistor configuration options associated with these pins will be automatically disconnected.
Rev. 1.00
44
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HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
