HMS87C5216 ETC1 [List of Unclassifed Manufacturers], HMS87C5216 Datasheet - Page 33

• Manufacturer Part Number: HMS87C5216
• Description: CMOS SINGLE-CHIP 8-BIT MICROCONTROLLER FOR UR(Universal Remocon) & WIRELESS KEYBOARD
• Manufacturer: ETC1 [List of Unclassifed Manufacturers]

R4 Port
R4 is an 1-bit CMOS bidirectional I/O port (address 0E7
I/O pin can independently used as an input or an output through
the R4DD register (address 0E8
R3 has internal pull-ups that is independently connected or dis-
connected by R4PC (address 0FC
are shown as below.
SEP. 2004 Ver 1.01
R4 Data Register (R/W)
R4
R4 Direction Register (W)
R4DD
R4 Pull-up Selection Register (W)
R4PC
R4 Open drain Assign Register (W)
R4ODC
R44 R43 R42 R41 R40
H
).
H
). The control registers for R4
ADDRESS : 0E7
RESET VALUE : Undefined
ADDRESS : 0E8
RESET VALUE : 00
ADDRESS :0FC
RESET VALUE : 00
ADDRESS :0E1
RESET VALUE : 00
Port Direction
0: Input
1: Output
Pull-up select
1: Without pull-up
0: With pull-up
Open drain select
0: Push-pull
1: Open drain
H
H
H
H
H
H
H
H
). Each
(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.
HMS87C5216