Active Low or Active High

[TechnoGilles]

Hi all,

First, let me say that I am comfortable with the concepts of active high and active low.

What I would like to know is some guidelines as to when to use one versus the other when defining my own microcontroller/CPLD signals.

I've read a few topics about that on the Web, most of which, I must say, didn't make sense at all !

Thank you !

 

[OlPhart]

some general musings...

> Active low on any signals that go external, so a cut cable or pulled connector causes inactive states.
> Similarly, switches/contacts are easier to debounce as active low.
> Internally, no preference other than simplest/fewest # of gates. Exploring each way is good mental exercise.

 

[TechnoGilles]

Thanks a lot for the tips. Make total sense to me !