HMS87C5216 ETC1 [List of Unclassifed Manufacturers], HMS87C5216 Datasheet - Page 32

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

HMS87C5216
R3 Port
R3 is an 8-bit CMOS bidirectional I/O port (address 0E5
I/O pin can independently used as an input or an output through
the R3DD register (address 0E6
R3 has internal pull-ups that is independently connected or dis-
connected by R3PC (address 0FB
are shown as below.
R3 Data Register (R/W)
R3
R3 Direction Register (W)
R3DD
R3 Pull-up Selection Register (W)
R3PC
R3 Open drain Assign Register (W)
R3ODC
R37 R36 R35 R34 R33 R32 R31 R30
H
).
H
). The control registers for R3
ADDRESS : 0E5
RESET VALUE : Undefined
ADDRESS : 0E6
RESET VALUE : 00
ADDRESS :0FB
RESET VALUE : 00
ADDRESS :0E0
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) R3 I/O Data Direction Register (R3DD)
R3 I/O Data Direction Register (R3DD) is 8-bit register, and can
assign input state or output state to each bit. If R3DD is ``1``, port
R3 is in the output state, and if ``0``, it is in the input state. R3DD
is write-only register. Since R3DD is initialized as ``00 h`` in re-
set state, the whole port R3 becomes input state.
(2) R3 Data Register (R3)
R3 data register (R3) is 8-bit register to store data of port R3.
When set as the output state by R3DD, and data is written in R3,
data is outputted into R3 pin. When set as the input state, input
state of pin is read. The initial value of R3 is unknown in reset
state.
(3) R3 Open drain Assign Register (R3ODC)
R3 Open Drain Assign Register (R3ODC) is 8bit register, and can
assign R3 port as open drain output port each bit, if corresponding
port is selected as output. If R3ODC is selected as ``1``, port R3
is open drain output, and if selected as ``0``, it is push-pull output.
R3ODC is write-only register and initialized as ``00 h`` in reset
state.
(4) R3 Pull-up Resistor Control Register (R3PC)
R3 pull-up resistor control register (R3PC) is 8-bit register and
can control pull-up on or off each bit, if corresponding port is se-
lected as input. If R3PC is selected as ``1``, pull-up ia disabled
and if selected as ``0``, it is enabled. R3PC 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