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What happens if unused ports are connected as a group to VDD0 or VSS0?

Latest Updated:12/01/2011

Question:

When pins are unused, it is written to independently connect them via a resistor.
Is it a problem if a number of unused ports are connected as a group to VDD0 or VSS0 ?

Answer:

This will cause problems.
A port may switch to output during the interval until reset becomes effective following power on or when the port mode is rewritten due to program defect, etc.
At this time, bundling unused pins may cause shorting between High and Low output pins.
Since this may cause damage to the microcontroller, it is necessary to handle each pin individually.
Suitable Products
RL78 Family
78K Family