HT46R064D/065D/066D
Enhanced A/D Type 8-Bit OTP MCU with LED Driver
I/O Port Control Registers
Each Port has its own control register, known as PAC, PBC, PCC, PDC 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 ²1². 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 ²0², 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 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
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 PAC0 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 and TC1 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
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 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 Pins
Pins PB6, PB7, PC6, PC7 on Port B and Port C 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.
Rev. 1.00
42
January 12, 2011
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
