Active high or low?

Archiver

I have a decent understanding of how active-high and active-low
switches work. But, why would I choose one way over the other? I
thought I saw an explanation in "What's a Microcontroller?", but I
can't seem to find that part again.

Thanks for any help.

Archiver

This is what I was taught, take it for what it's worth:

Many engineers prefer active-low inputs because this puts a resistor
(the pull-up) between the button and the Vdd side of the circuit. If
there was a static discharge from the user to the pushbutton the
resistor would limit the current to the Vdd side.

For all I know this is a wive's tale ... but it works for me.

-- Jon Williams
-- Applications Engineer, Parallax
-- Dallas Office

---

Original Message

---

From: dave_heathcb [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=otI2mLR2vWaPsdN0MzNHaSXfHUubbWjTo56A_hpDIKY9twLN-7iW6wBUzibSskDRI6DqOgT1K67QC3Rz]dave_h425@h...[/url
Sent: Sunday, April 11, 2004 4:23 PM
To: basicstamps@yahoogroups.com
Subject: [noparse][[/noparse]basicstamps] Active high or low?


I have a decent understanding of how active-high and active-low
switches work. But, why would I choose one way over the other? I
thought I saw an explanation in "What's a Microcontroller?", but I
can't seem to find that part again.

Thanks for any help.