Rotary potentiometer with steps/positions

Ok, this is probably not the “correct” way of describing it so please bear with me. :slight_smile:

I’m looking for a rotary potentiometer that has pre-defined “steps/positions”. I’d like to use it to change pages on a LCD-screen, each position of the potentiometer would be one page. The “feel” would be a lot better if I could match each page with a defined position on the knob.

It would be good if it had the aprox same dimensions as this one since I have a number of knobs for it.
Pot: http://www.ebay.com/itm/221132272705?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648
Knob: http://www.ebay.com/itm/321038173376?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2648

Alps has some but they tend to be quite expensive.

A cheaper solution would be to use a rotary switch to control a digital pot.

What you're after is a called "rotary encoder"

http://www.ebay.com/sch/i.html?_nkw=12mm+rotary+encoder

There's libraries, etc. for them on the Arduino web site.

What you're after is a called "rotary encoder"

Yes but you can get them with or without "dents" these dents are the click that you feel when you turn it. You can also get different number of dents per revolution.

Grumpy_Mike:

What you're after is a called "rotary encoder"

Yes but you can get them with or without "dents" these dents are the click that you feel when you turn it. You can also get different number of dents per revolution.

The technical name for which is "detents", although "dents" is sure to get you a laugh.

The term potentiometer is incorrect in this situation, as a potentiometer is a type of variable resistor. As noted by others, a rotary encoder is what you are looking for.

The technical name for which is "detents", although "dents" is sure to get you a laugh.

Yep dyslexia and an iPad are not friends ;)

Well there are/were pots that had mechanical detents, used a lot is older stereo systems to give it a higher tech feel I guess.

Lefty

Grumpy_Mike:

The technical name for which is "detents", although "dents" is sure to get you a laugh.

Yep dyslexia and an iPad are not friends ;)

We might believe that excuse if you'd only typed it once... :.

retrolefty: Well there are/were pots that had mechanical detents, used a lot is older stereo systems to give it a higher tech feel I guess.

Lefty

Agreed, but one wouldn't normally use one of those to select pages on an LCD like OP wants.

A pot with detents sounds like a really bad idea if the pot gets dirty at one of the detents. Probably why they use encoders for that application nowadays.

Grumpy_Mike:

The technical name for which is "detents", although "dents" is sure to get you a laugh.

Yep dyslexia and an iPad are not friends ;)

I can sympathize. I get some pretty funny autocorrects from my iDevices. :)

Actually I think a standard pot with or without detents could make a fine menu selection input device. Just wire the pot ends to ground and +5vdc and after reading a pot wiper value do a right shift of say 6 bits, so the resulting pot values would be 16 distinct values depending on pot position, that could be used to select 16 different menu items in the coding.

Lefty

retrolefty: Actually I think a standard pot with or without detents could make a fine menu selection input device. Just wire the pot ends to ground and +5vdc and after reading a pot wiper value do a right shift of say 6 bits, so the resulting pot values would be 16 distinct values depending on pot position, that could be used to select 16 different menu items in the coding.

Lefty

That would certainly work. You would a have a constant position of the knob for each menu item which may or may not be desirable. It might make the software slightly more complicated for when you wanted to add/delete menu pages. Another way for sure.

retrolefty:
Actually I think a standard pot with or without detents could make a fine menu selection input device. Just wire the pot ends to ground and +5vdc and after reading a pot wiper value do a right shift of say 6 bits, so the resulting pot values would be 16 distinct values depending on pot position, that could be used to select 16 different menu items in the coding.

Nope. It works if there’s only one menu (with exactly 16 items in it!) but it falls apart for anything more.

eg. Suppose you select a value in a sub-menu … the pot will be in the wrong position when you return to the main menu (and it was probably in the wrong position when you went into the sub menu, too…)

Rotary encoders don’t have any of those problems.

fungus:

retrolefty: Actually I think a standard pot with or without detents could make a fine menu selection input device. Just wire the pot ends to ground and +5vdc and after reading a pot wiper value do a right shift of say 6 bits, so the resulting pot values would be 16 distinct values depending on pot position, that could be used to select 16 different menu items in the coding.

Nope. It works if there's only one menu (with exactly 16 items in it!) but it falls apart for anything more.

eg. Suppose you select a value in a sub-menu ... the pot will be in the wrong position when you return to the main menu (and it was probably in the wrong position when you went into the sub menu, too...)

Rotary encoders don't have any of those problems.

You just lack imagination. There is never a 'wrong' position to be in until you do something to tell the software to accept that selection. ;)

I feel it could be a simple reliable menu pointing device if the sketch is designed correctly knowing before hand the maximum items for the menus and submenus before deciding how many shifts to make on the analog input readings. It's just software. Most menu selection interfaces require a second input, usually a button press to say yes that is the selection I want. ;)

Lefty

retrolefty:
You just lack imagination. There is never a ‘wrong’ position to be in

Yes there is.

Suppose you have a menu. The fourth option is ‘color’

You select ‘color’ and a sub menu appears. You select ‘red’, it’s the the first click from the left on the pot. The LED turns red as a result and you get sent back to the main menu.

The main menu is now out of sync. If ‘color’ is still selected then the pot is in the wrong position. If ‘color’ isn’t selected then the menu isn’t very intuitive to use (the currently selected item will depend on the color you selected in the submenu).

Now suppose you go back to the ‘color’ submenu. It should have ‘red’ highlighted (the current LED color). Problem is, ‘color’ is the fourth option in the main menu so the pot isn’t in the right place to do that.

It doesn’t work.

It doesn't work.

I agree in your mind it doesn't work. In my mind I can make it work perfectly. You seem to thinking turning among the options offered is the same as selecting an option, there is always another user action required to select the displayed option. Lets leave it at that.

Lefty

It works perfectly... providing that you choose to save the previous state so re entry places you at the position you exited at. Positional feedback must be from the visual display and not the knob. You don't read the knob you use the knob to read... Regardless of what the knob really is, rotary encoder, pot or rotary switch. Using a rotary encoder is probably the best move as it doesn't have the 270 deg rotational limitation of a pot or the mechanical stops that most rotary switches do. {Edit RKJ}

Bob

Thanks for the suggestions and ideas. For me I guess a normal pot would be ok since I only need to. Switch between 2-3 pages.

Now the next question. Can I use a digital (pwm) pin for this? This can be made to know what position the pot is right or do I need an analog pin?

What type of pin should I use for a rotary encoder?

Boopidoo: Thanks for the suggestions and ideas. For me I guess a normal pot would be ok since I only need to. Switch between 2-3 pages.

Now the next question. Can I use a digital (pwm) pin for this? This can be made to know what position the pot is right or do I need an analog pin?

What type of pin should I use for a rotary encoder?

A digital pin used in PWM service is an output pin, it could not be used to 'read' anything. Reading something is an inputting function for your arduino board. An analog pin must be used to read a pot because a pot is only capable of generating a variable DC output voltage to be wired to a analog input pin. A rotary encoder needs to use two digital input pins and depending if you want to use interrupts to service the encoder or not you may be limited to using digital pins 2 and/or 3.

Lefty

Ah, of course, thanks!

I think I might need to buy a Mega since I’m running out of pins. :slight_smile: