CHAPTER 2 PIN FUNCTIONS
User’s Manual U15109EJ3V0UD
80
(16) P170 to P176 (port 17) ··· 3-state I/O
P170 to P176 function as a 7-bit I/O port in which input and output can be specified in 1-bit units.
In addition to I/O port pins, these pins can also be used as V
DD0
=
4.5 V monitor output. During 8-bit access of
port 17, the highest bit is ignored during a write operation and is read as “0” during a read operation.
(a) Port function
P170 to P176 can be set to input or output in 1-bit units using the port 17 mode register (PM17).
(b) Alternate function
(i)
VM45 (V
DD0
====
4.5 V monitor output) … Output
This is the V
DD0
=
4.5 V monitor output pin.
(17) RESET (reset) ··· Input
RESET is a signal that is input asynchronously and has a constant low level width regardless of the status of
the operating clock. When this signal is input, a system reset is executed as the first priority ahead of all other
operations.
In addition to being used for ordinary initialization/start operations, this signal can also be used to cancel a
standby mode (HALT, IDLE, or STOP mode).
(18) Mode (mode)
This is pin used in other than the
µ
PD78F3089.
Connect to GND0 to GND2 in normal operating mode.
(19) CLKOUT (clock output) ··· Output
This pin outputs internally generated bus clocks.
(20) X1, X2 (crystal)
These pins are used to connect the resonator that generates the main clock.
(21) XT1, XT2 (crystal for sub-clock)
These pins are used to connect the resonator that generates the subclock.
(22) ADCV
DD
(power supply for analog)
This is the analog power supply pin for the A/D converter and alternate-function ports.
This pin also functions as a reference voltage pin for the A/D converter.
(23) ADCGND (ground for analog)
This is the ground pin for the A/D converter and alternate-function ports.
(24) CPUREG (regulator control)
This is the regulator pin for the CPU power supply. Connect this pin to GND0 to GND2 via a capacitor of 1
µ
F
(recommended value).