Datasheet

37
1.3.3 Pin Functions
Table 1.7 lists the pin functions.
Table 1.7 Pin Functions
Classification Symbol I/O Name Function
Power supply V
CC
I Supply Connects to power supply.
Connect all V
CC
pins to the system
supply. No operation will occur if
there are any open pins.
V
SS
I Ground Connects to ground.
Connect all V
SS
pins to the system
ground. No operation will occur if
there are any open pins.
V
PP
I Program
supply
Connects to the power supply (V
CC
)
during normal operation.
When in PROM mode, apply 12.5 V.
Clock PLLVCC I PLL supply On-chip PLL oscillator supply.
PLLVSS I PLL ground On-chip PLL oscillator ground.
PLLCAP I PLL
capacitance
On-chip PLL oscillator external
capacitance connection pin.
EXTAL I External clock Connect a crystal oscillator. Also, an
external clock can be input to the
EXTAL pin.
XTAL I Crystal Connect a crystal oscillator.
CK O System clock Supplies the system clock to
peripheral devices.
System control RES I Power-on reset Power-on reset when low
MRES I Manual reset Manual reset when low
WDTOVF O Watchdog
timer overflow
Overflow output signal from WDT
BREQ I Bus request Goes low when external device
requests bus right release
BACK O Bus request
acknowledge
Indicates that bus right has been
released to external device. The
device that output the BREQ signal
receives the BACK signal, notifying
the device that it has obtained the bus
right.