HMS87C5216 Datasheet, PDF(33/76 Page) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD

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HMS87C5216 Datasheet, PDF (33/76 Pages) List of Unclassifed Manufacturers – CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD

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HMS87C5216

R4 Port

R4 is an 1-bit CMOS bidirectional I/O port (address 0E7H). Each

I/O pin can independently used as an input or an output through

the R4DD register (address 0E8H).

R3 has internal pull-ups that is independently connected or dis-

connected by R4PC (address 0FCH). The control registers for R4

are shown as below.

R4 Data Register (R/W)

ADDRESS : 0E7H

RESET VALUE : Undefined

R44 R43 R42 R41 R40

R4 Direction Register (W)

R4DD

ADDRESS : 0E8H

RESET VALUE : 00H

Port Direction

0: Input

1: Output

R4 Pull-up Selection Register (W)

R4PC

ADDRESS :0FCH

RESET VALUE : 00H

Pull-up select

1: Without pull-up

0: With pull-up

R4 Open drain Assign Register (W)

ADDRESS :0E1H

RESET VALUE : 00H

R4ODC

Open drain select

0: Push-pull

1: Open drain

(1) R4 I/O Data Direction Register (R4DD)

R4 I/O Data Direction Register (R4DD) is 1-bit register, and can

assign input state or output state to each bit. If R4DD is ``1``, port

R4 is in the output state, and if ``0``, it is in the input state. R4DD

is write-only register. Since R4DD is initialized as ``00 h`` in re-

set state, the whole port R4 becomes input state.

(2) R4 Data Register (R4)

R4 data register (R4) is 1-bit register to store data of port R4.

When set as the output state by R4DD, and data is written in R4,

data is outputted into R4 pin. When set as the input state, input

state of pin is read. The initial value of R4 is unknown in reset

state.

(3) R4 Open drain Assign Register (R4ODC)

R4 Open Drain Assign Register (R4ODC) is 1-bit register, and

can assign R4 port as open drain output port each bit, if corre-

sponding port is selected as output. If R4ODC is selected as ``1``,

port R4 is open drain output, and if selected as ``0``, it is push-

pull output. R4ODC is write-only register and initialized as ``00

h`` in reset state.

(4) R4 Pull-up Resistor Control Register (R4PC)

R4 pull-up resistor control register (R4PC) is 1-bit register and

can control pull-up on or off each bit, if corresponding port is se-

lected as input. If R4PC is selected as ``1``, pull-up ia disabled

and if selected as ``0``, it is enabled. R4PC is write-only register

and initialized as ``00 h`` in reset state. The pull-up is automati-

cally disabled, if corresponding port is selected as output.

SEP. 2004 Ver 1.01

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