HT48R02B datasheet(30/71 Pages) HOLTEK

30 / 71 page

HT46R01B/02B/01N/02N

HT48R01B/02B/01N/02N

Rev.1.00

December 15, 2009

I/O Port Control Registers

Each Port has its own control register, known as PAC,

PBC, which controls the input/output configuration. With

this control register, each I/O pin with or without

pull-high resistors can be reconfigured dynamically un-

der software control. For the I/O pin to function as an in-

put, 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 en-

hanced by the use of pins that have more than one func-

tion. Limited numbers of pins can force serious design

constraints on designers but by supplying pins with

multi-functions, many of these difficulties can be over-

come. 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 pro-

gram 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 pro-

grammed. 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 appro-

priate 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 Coun-

ter 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 in-

puts by setting the appropriate bit in the Port Control

lected 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 selec-

tion, 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 selec-

tions, even if the PWM registers have enabled the

PWM function.

· A/D Inputs

Each device in this series has either four or eight in-

puts to the A/D converter. All of these analog inputs

are pin-shared with I/O pins on Port B. If these pins

are to be used as A/D inputs and not as I/O pins then

the corresponding PCRn bits in the A/D converter

control register, ADCR, 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 re-

sistor configuration options remain, however if used

as A/D inputs then any pull-high resistor configuration

options associated with these pins will be automati-

cally disconnected.

HT48R02B Datasheet(PDF) 30 Page - Holtek Semiconductor Inc

HT48R02B Datasheet(HTML) 30 Page - Holtek Semiconductor Inc

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