
MB89120/120A Series
6
I
PIN DESCRIPTION
(Continued)
Pin no.
Pin name
Circuit type
Function
5
X0
A
Main clock crystal oscillator pins (max. 4.2 MHz)
6
X1
8
X0A
B
Subclock crystal oscillator pins (for 32.768 kHz)
9
X1A
3
MOD0
C
Operation mode select pins
Connect these pins directly to V
SS
.
4
MOD1
2
RST
D
Reset I/O pin
This port is of N-ch open-drain output type with pull-up re-
sistor and a hysteresis input type. The internal circuit is ini-
tialized by the input of “L”. “L” is output from this pin by an
internal reset source as optional setting.
27 to 34
P07/ (INT27) to
P00/ (INT20)
I
General-purpose I/O ports
On the MB89120A series, these pins also serve as exter-
nal interrupt input.
External interrupt input is hysteresis input.
18, 20 to 26
P17 to P10
E
General-purpose I/O ports
10 to 17
P27 to P20
G
General-purpose output-only ports
42
P30/SCK
F
General-purpose I/O port
Also serves as clock I/O for the 8-bit serial I/O interface.
This port is of hysteresis input type.
41
P31/SO
F
General-purpose I/O port
Also serves as a serial I/O data output. This port is of hys-
teresis input type.
40
P32/SI
F
General-purpose I/O port
Also serves as a serial I/O data input. This port is of hys-
teresis input type.
39
P33/EC/SCO
F
General-purpose I/O port
Also serves as the external clock input for the 8-bit timer/
counter. This port is of hysteresis input type.
System clock output is optional.
38
P34/TO/INT0
F
General-purpose I/O port
Also serves as the overflow output and external
interrupt input for the 8-bit timer/counter. This port is of
hysteresis input type.
36,
37
P36/INT2,
P35/INT1
F
General-purpose I/O ports
Also serve as an external interrupt input. These ports are
of hysteresis input type.
35
P37/BZ/ (RCO)
F
General-purpose I/O port
Also serves as a buzzer output. This port is of
hysteresis input type. On the MB89120A series, the pin
also serves as a remote control output.