Chapter 1
Overview
Cautions for Circuit Setup I - 37
Input and Output pin
When the direction of unused I/O pin is set to input, pull-up or down the pin with the resistor, the value of which
is typically between 10 kΩ and 100 kΩ.
When the unused I/O pin is configured as output, it should be left unconnected.
Figure:1.6.4 Unused I/O Pins
Recommended Condition of Each Pin *3
Pin name Input/Output Recommended condition of unused pins
P00 to P07
P10 to P17
P20 to P26
P30 to P37
P40 to P47
P50 to P57
P60 to P67
P70 to P77
P80 to P85
Input/output
Input
Pull-up (or down) the pins with the resistor, the value of which is typically between 10 kΩ and
100 kΩ. *1 *2
Output Unconnect the pins.
XI Input Unconnect the pins.
XO Output Unconnect the pins.
P27 Input/output
When connecting capacitors between P27 and V
SS
, the discharge diodes between P27 and
V
DD30
should be connected
.
VREFP -
Set V
REFP
= V
DD30.
NATRON Input
Pull-up the pin to V
DD30
(when auto reset function is disabled) or pull-down the pin to V
SS
(when auto reset function is enabled) with the resistor, the value of which is typically
between 10 kΩ and 100 kΩ.
DMOD Input
Pull-down the pin to V
SS
with the resistor, the value of which is typically between 1.5 kΩ and
100 kΩ. (Recommendation: between 10 kΩ and 100 kΩ)
*1 When unused pins are not connected, the microcomputer does not have the problem. However, it is easily influenced by the serge or
noise. Evaluate enough for determining the appropriate configuration.
*2 When pins are unused, set them to the general-purpose port function.
*3 Evaluate enough in consideration of the influence by exogenous noise and decide the condition of each pin.
Input Input
Data Data
Output OFF
Input Enable Input Enable
Output OFF
Pull-up
resistor
Pull-down
resistor
Output Control Output Control
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