µ
PD78C14(A)
7
2. PIN FUNCTIONS
2.1 Pin Function List
Pin
Input/Output
Function
PA7-PA0
Input/Output
These 8 pins constitute an 8-bit I/O port and input/output can be specified in bit
(Port A)
units.
PB7-PB0
Input/Output
These 8 pins constitute an 8-bit I/O port and input/output can be specified in bit
(Port B)
units.
PC0/TxD
Input/Output,
Port C
Transmit Data
Output
These 8 pins constitute an 8-bit I/O
This pin outputs serial data.
PC1/RxD
Input/Output,
port and input/output can be specified
Receive Data
Input
in bit units.
This pin inputs serial data.
PC2/SCK
Input/Output,
Serial Clock
Input/Output
This pin inputs/outputs serial clock. It be-
comes an output pin when an internal
clock is used or an input pin when an
external clock is used.
PC3/INT2/TI
Input/Output,
Interrupt Request/Timer Input
Input, Input
This pin inputs edge triggering (falling
edge) maskable interrupt or external
clock for timer. This pin is also shared
with zero-cross detection pin for AC input.
PC4/TO
Input/Output,
Timer Output
Output
This pin outputs square waves in which
one cycle of the internal clock forms a
half cycle, indicating the timer’s counting
time.
PC5/CI
Input/Output,
Counter Input
Input
This pin inputs external pulse for timer/
event counter.
PC6/CO0
Input/Output,
Counter Output 0,1
PC7/CO1
Output
This pin outputs programmable square
wave by timer/event counter.
PD7-PD0/
Input/Output,
Port D
Address/Data Bus
AD7-AD0
Input/Output
These 8 pins constitute an 8-bit I/O
These pins function as multiplexed
port and input/output can be
address/data bus when using an
specified in byte units.
external memory.
PF7-PF0/
Input/Output,
Port F
Address Bus
AB15-AB8
Output
These 8 pins constitute an 8-bit I/O
These pins function as address bus when
port and input/output can be specified
using an external memory.
in bit units.
WR
Output
This is a strobe signal output to write data in external memory. This signal
(Write
becomes high level except during the data write machine cycle for external memory.
Strobe)
This signal becomes output high impedance when the RESET signal is low or in
the hardware STOP mode.
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