What is the preferred procedure concerning dangling pins on an Arduino board?
Dangling? Would you mean 'Floating' (input with no signal source attached)?
It's not really like the IC gate world, where you tie them high to keep the output low.
If you don't read them, it doesn't seem that it would be an issue, but, you could set the Pull_up's on, or manually tie them to V+ with a moderately high value resistor, or set them as outputs.
Floating inputs can act like antennae and give false positives (High state), which may affect other things unexpectedly.
Take a look at 'Inputs'. good stuff.
pinMode(unusedPin, INPUT_PULLUP);
is the preferred method to keep the pins from switching due to electric fields in the environment, which can cause higher power use and internal noise. Especially on completed projects, make sure all inputs are accounted for.
It's just like in the IC gate world, only the gate outputs are internal to the chip.
Oops,,,,,
And just so you know that CrossRoads isn't just making this up, this is described in Section 18.2.6 Unconnected Pins:
Thanks folks. Floaters is the word I should have used but I had been using a B-spice simmer where open components are said to be dangling. Floaters or danglers, ta.