HYUNDAI MicroElectronics
GMS82512/16/24
R4 and R4DD register:
R4 is an 5-bit CMOS bidirection-
In addition, Port R4 is multiplexed with various special
features. The control register PMR4 (address 0D0H) con-
trols the selection of alternate function. After reset, this
value is “0”, port may be used as normal I/O port.
To use alternate function such as external interrupt or ex-
ternal counter input, write “1” in the corresponding bit of
PMR4.
al I/O port (address 0C8H). Each I/O pin can independently
used as an input or an output through the R4DD register
(address 0C9H).
ADDRESS: 0C8
H
R4 Data Register
RESET VALUE: Undefined
-
-
-
R44 R43 R42 R41 R40
R4
Port Pin
Alternate Function
R40
R41
R42
R43
R44
INT0 (External Interrupt 0)
INT1 (External Interrupt 1)
INT2 (External Interrupt 2)
INT3 (External Interrupt 3)
EC0 (External count input to Timer/
Counter 0)
Input / Output data
ADDRESS: 0C9
H
R4 Direction Register
RESET VALUE: 00
H
-
-
-
R4DD
Regardless of the direction register R4DD, PMR4 is select-
ed to use as alternate functions, port pin can be used as a
corresponding alternate features.
Port Direction
0: Input
1: Output
ADDRESS: 0D0
RESET VALUE: 00
H
R4 Port Mode Register
H
-
-
-
4
3
2
1
0
PMR4
0: R40
1: INT0
0: R41
1: INT1
0: R42
1: INT2
0: R43
1: INT3
0: R44
1: EC0
ADDRESS: 0F8H
RESET VALUE: 00H
Edge Selection Register
7
6
5
4
3
2
1
0
IEDS
INT3
INT2
INT1
INT0
External Interrupt Edge Select
00: Reserved
01: Falling (1-to-0 transition)
10: Rising (0-to-1 transition)
11: Both (Rising & Falling)
FEB. 2000 Ver 1.00
29
HYNIX [ HYNIX SEMICONDUCTOR ]
