
CHAPTER 2 PIN FUNCTIONS
User’s Manual U17260EJ6V0UD
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(a) KR0 to KR7
These are the key interrupt input pins
2.2.9 P120 to P124 (port 12)
P120 to P124 function as a 5-bit I/O port. These pins also function as pins for external interrupt request input,
potential input for external low-voltage detection, connecting resonator for main system clock, connecting resonator
for subsystem clock, external clock input for main system clock, and external clock input for subsystem clock. The
following operation modes can be specified in 1-bit units.
(1) Port mode
P120 to P124 function as a 5-bit I/O port. P120 to P124 can be set to input or output port using port mode
register 12 (PM12). Only for P120, use of an on-chip pull-up resistor can be specified by pull-up resistor option
register 12 (PU12).
(2) Control mode
P120 to P124 function as pins for external interrupt request input, potential input for external low-voltage
detection, connecting resonator for main system clock, connecting resonator for subsystem clock, external clock
input for main system clock, and external clock input for subsystem clock.
(a) INTP0
This functions as an external interrupt request input (INTP0) for which the valid edge (rising edge, falling
edge, or both rising and falling edges) can be specified.
(b) EXLVI
This is a potential input pin for external low-voltage detection.
(c) X1, X2
These are the pins for connecting a resonator for main system clock.
(d) EXCLK
This is an external clock input pin for main system clock.
(e) XT1, XT2
These are the pins for connecting a resonator for subsystem clock.
(f)
EXCLKS
This is an external clock input pin for subsystem clock.
Caution
For products without an on-chip debug function and with the flash memory of 48 KB or
more (
PD78F0534, 78F0535, 78F0536, and 78F0537) and having a product rank of “I”, “K”,
or “E”, and for the product with an on-chip debug function (
PD78F0537D), connect
P121/X1/OCD0A
Note
as follows when writing the flash memory with a flash memory
programmer.
P121/X1/OCD0ANote: When using this pin as a port, connect it to VSS via a resistor (10 k:
recommended) (in the input mode) or leave it open (in the output
mode).
The above connection is not necessary when writing the flash memory by means of self
programming.