Hello and thanks always for your help.

I have a quick and simple question.
We all know about switches. They can be open or close, on or off and they can transmit a binary value to the input of an IC or turn on a lamp or whatever.

But what if I want to implement some circuit in which three (or more) states are necessary. I first limit it to three states because I dont want the discussion to go to a potentiometer and A/D converter. Let's say I need just three states.

It doesnt necessarily have to be switches.. is there some kind of electronic part with which I can implement this (and so that the program in my IC can now if I am in stage 1 or 2 or 3??

EDIT: Thinking more about this, I ve come to using two switches which would give me a 2 bit signal 00 01 10 11 that gives me 4 options and use two pins of my IC. However I would like something more permanent that I dont need to be pressing the switch all the time..


I guess if I want to use only one pin that would imply using analog signals....
Anyway, any other ideas you guys have??

 

Hello,

The modern approach is to use a single push button switch and count the pushes. Each push represents a different state you need to detect. I dont always like this, but if there are not that many states it works ok.

 

Toggle switches don't need to be pressed all the time.

Have you considered rotary switches, that have multiple throws? They have multiple poles, too. For example, a 3P4T switch )I just made that up; unsure if that exact configuration is available).

If the number of positions is small, such a switch is available as a slide switch. Think of an old boom box, with a slide switch choosing between AM, FM, CD, or Aux.

There are also rotary encoders. I am think for example of a thumb wheel switch, that encodes decimal to BCD.

You didn't mention how many states you want to select between?