could some one tell me what is the best practice for unused pin ?
the goal is to have minimum consumption
a. setting the pin as input and connecting to VCC via pull-up resistor ?
b. like a but connecting to GND
c. setting the pin as input but leaving “on-air” (no connection)
d. setting the pin as output with 0 value
Thank in advance
Use of external pullup or pulldown is essential for those really keen on getting a well defined result.This is the single biggest must-do here.
The Arduino Yún is a microcontroller board based on the ATmega32u4 and the Atheros AR9331.
ATmega32u4 is 5V logic.
AR9331 is 2.5V logic.
In other word AR9331 has far more ESD susceptibility.
How Yun did at unused pin?
Go read Yun diagram, and surprise!