GMS81C5108
Port R1 is multiplexed with various special features.The
control registers controls the selection of alternate func-
tion. After reset, this value is “0”, port may be used as nor-
mal I/O port. The way to select alternate function such as
comparator input or buzzer will be shown in each periph-
eral section.
R3 Port
R3 is a 4-bit CMOS bidirectional I/O port (address 0C3H).
Each I/O pin can independently used as an input or an out-
put through the R3DR register (address 0CBH).
In addition, R1 port is used as key scan function which op-
erate with normal input port.
ADDRESS: 0C3
RESET VALUE: ----0000
H
R3 Data Register
B
B
R33 R32 R31 R30
-
-
-
-
-
R3
Input or output is configured automatically by each func-
tion register (KSMR) regardless of R1DR.
ADDRESS : 0CB
RESET VALUE : ----0000
H
R3 Direction Register
R2 Port
-
-
-
R3DR
R2 is a 4-bit CMOS bidirectional I/O port (address 0C2H).
Each I/O pin can independently used as an input or an out-
put through the R2DR register (address 0CAH).
Port Direction
0: Input
1: Output
R2 has internal pull-ups that is independently connected or
disconnected by R2PU (address 0D2H). The control regis-
ters for R2 are shown as below.
R3 Pull-up
Selection Register
ADDRESS : 0D3
RESET VALUE : ----0000
H
B
-
-
-
-
R3PU
ADDRESS: 0C2
H
RESET VALUE: ----0000
Pull-up select
0: Without pull-up
1: With pull-up
R2 Data Register
B
R23 R22 R21 R20
-
-
-
-
-
R2
R3 Open Drain
Selection Register
ADDRESS : 0D7
H
RESET VALUE : ----0000
B
ADDRESS : 0CA
H
-
-
-
-
R3CR
R2 Direction Register
RESET VALUE : ----0000
B
-
-
-
R2DR
Pull-up select
0: No Open Drain
1: Open Drain
Port Direction
0: Input
1: Output
SEG0~SEG36
R2 Pull-up
Selection Register
ADDRESS : 0D2
RESET VALUE : ----0000
H
Segment signal output pins for the LCD display. See "19.
LCD DRIVER" on page 71 for details.
B
-
-
-
-
R2PU
Pull-up select
0: Without pull-up
1: With pull-up
COM0~COM3
Common signal output pins for the LCD display. See "19.
LCD DRIVER" on page 71 for details.
R2 Open Drain
ADDRESS : 0D6
H
Selection Register
RESET VALUE : ----0000
B
SEG34~SEG36 and COM1~COM3 are selected by LCDD
of the LCR register.
-
-
-
-
R2CR
Pull-up select
0: No Open Drain
1: Open Drain
JUNE 2001 Ver 1.0
33
HYNIX [ HYNIX SEMICONDUCTOR ]
