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Topic: What to do with unused pins (Read 1 time) previous topic - next topic

Coding Badly


The recommended practice, only if the processor will be put to sleep...

Quote
13.2.6 Unconnected Pins
If some pins are unused, it is recommended to ensure that these pins have a defined level. ... The simplest method to ensure a defined level of an unused pin, is to enable the internal pull-up.

Jassper



The recommended practice, only if the processor will be put to sleep...

Quote
13.2.6 Unconnected Pins
If some pins are unused, it is recommended to ensure that these pins have a defined level. ... The simplest method to ensure a defined level of an unused pin, is to enable the internal pull-up.



Doesn't that cause a bit more current consumption by the processor? If it's pulled to a 5v level via internal resistors, power must be flowing.

Grumpy_Mike

Not very much because the input has so high an impedance.

Coding Badly

Doesn't that cause a bit more current consumption by the processor? If it's pulled to a 5v level via internal resistors, power must be flowing.


I have a handheld gadget that: runs from 2 AA alkaline batters, is used a few times every day, for 30 minutes to one hour.  This is the third year of its existence and it is still running problem-free on the original AA batteries.  The unused pins are held high by internal pullups.

In my experience, any current consumption from the internal pullups enabled on unconnected pins is so very small as to be essentially zero.

Jassper


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