Dont keep your inputs floating!!!
June 8, 2010
I keep hearing and reading about the importance of making sure all the unused inputs are pulled low with a resistor. No reason is given other than "don't keep them floating because you'll get unpredictable results!"
If you take a look at the picaxe 28X board, you see that all the digital inputs are pulled low with a 10K resistor. I understand that this makes it easier to just connect a switch to the pins on the board without having to add an external resistor. The analog inputs are left floating, almost as if by design.
Some people add jumpers next to the analog inputs so they are tied down, like here.
Can anyone explain why it is better to tie down the inputs? Is there a professor-Rik-like way to demonstrate a situation where not connecting them to ground makes the circuit fail?