HT46R0664 datasheet(42/92 Pages) HOLTEK

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Rev. 1.00

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HT46R0664

Enhanced A/D+LCD Type 8-Bit OTP MCU

I/O Port Control Registers

Each Port has its own control register, known as PAC, PBC, PCC, PDC, PEC, PFC 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 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 pins, INTn, are pin-shared with I/O pins. To use the pin as an external

interrupt input the correct bits in the MFIC register must be programmed. The pin must also be

setup as an input by setting the Input/Output Port Control Register 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.

● BZ output

The BZ function output is pin-shared with an I/O pin. The output function of this pin is chosen

using the CTRL2 register. 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 BZ function

has been selected.

● 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 register. 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.

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