HITACHI 9
1.3.2
Pin Functions
Table 1.3 describes the pin functions.
Table 1.3
Pin Functions
Type
Symbol
Pin No.
I/O
Name and Function
Power
V
CC
13, 38,
63, 73,
80, 88
I
Power: Connected to the power supply. Connect all
V
CC
pins to the system power supply . The chip will not
operate if any V
CC
pin is left unconnected.
Ground: Connected to ground. Connect all V
SS
pins to
the system ground. The chip will not operate if any V
SS
pin is left unconnected.
V
SS
4, 15, 24,
32, 41,
50, 59,
70, 81,
82, 92
I
V
PP
76*
I
RES pin in the MCU mode. Apply +12.5V when
programming the PROM in the SH7021 (PROM
version).
Clock
EXTAL
71
I
Crystal/external clock: Connected to a crystal resonator
or external clock input having the same frequency as
the system clock (CK).
XTAL
72
I
Crystal: Connected to a crystal resonator with the same
frequency as the system clock (CK). If an external clock
is input at the EXTAL pin, leave XTAL open.
CK
69
O
System clock: Supplies the system clock (CK) to
peripheral devices.
System
control
RES
76
I
Reset: Low input causes a power-on reset if NMI is
high, or a manual reset if NMI is low.
WDTOVF
75
O
Watchdog timer overflow: Overflow output signal from
the watchdog timer.
BREQ
60
I
Bus request: Driven low by an external device to
request the bus ownership.
BACK
58
O
Bus request acknowledge: Indicates that bus ownership
has been granted to an external device. By receiving
the
BACK
signal, a device that has sent a
BREQ
signal
can confirm that it has been granted the bus.
Note:
Pin 76 is RES in the SH7020, SH7021 (Masked ROM version) and Vpp in the SH7021
(PROM version).