Matrix Orbital Corp

is there any way to hook up a potentiometer to the keypad input on a lcd display?

Why?

to use it as a volume control and/or a menu selection button.

JohnC602 wrote:to use it as a volume control and/or a menu selection button.

A pot is not really the correct thing to use in this case. The keypad is looking for button presses, so you want to use a device that turns switches on and off when the knob is rotated. I have the following on order from Mouser for just this purpose:

688-EC11B15242AF INCREMENTAL ENCODER
688-RKJXT1E12001 8-DIRECTIONAL SWITCH AND ENCODER with CENTER PUSH

Look those numbers up at

http://www.mouser.com/

and take a look at them by clicking on the catalog page link. You could use a POT, but the solution would be messy. -Chuck-

could you please keep me posted and fill me in on exactly how these things work as for as wiring and things go.

Thanks,

JohnC

Would I be right in thinking, these devices should just work by sending a number of pulses, so effectively its breaking and making the circuit, simulating many button presses as you move it up and down. So you would just hook it up to two of the keypad inputs?

Pheonix wrote:Would I be right in thinking, these devices should just work by sending a number of pulses, so effectively its breaking and making the circuit, simulating many button presses as you move it up and down. So you would just hook it up to two of the keypad inputs?

I believe that is correct, except that they are just switches. Nothing to generate ongoing button presses. If I remember, I chose the rotating encoder that gives 30 switch opens/closes per rotation, but there are various switch-counts-per-rotation versions on that catalog page. The Optical Encoders (elsewhere in the catalog) give thousands of switch changes per revolution, but they are quite expensive and you do not need that for this type application.

The Joystick like device just gives a single keypress (one of nine keys, depending on the direction and center push) so you would want to set the LCD to auto-repeat. -Chuck-

Some confusion here:

Encoders, normally, not works by switching, works by generating pulses, these encoders also can have detents, little clicks in each position, if a encoder is incremental, it generates at least two channels of pulses (A and B) you must use these two channels to detect if encoder is rotating to left or right side, normally electronic circuits are used for this purpose.

dtorner wrote:Some confusion here:

Encoders, normally, not works by switching, works by generating pulses, these encoders also can have detents, little clicks in each position, if a encoder is incremental, it generates at least two channels of pulses (A and B) you must use these two channels to detect if encoder is rotating to left or right side, normally electronic circuits are used for this purpose.

Yes, but the pulses are just switch opens and closes. There are a pair of them and the direction depends on the order received. There is a good read on them at:

http://www.mcmanis.com/chuck/robotics/p ... atrak.html

Chuck, the author, is a friend from the local robotics club, and though we share the same first name, we are not the same person. He is much smarter than I am.

I am not sure that I can use them with the LCD, but I hope to! Will let you know when I get them hooked up. -Chuck-

Got the devices. Have not hooked them up, but the RKJXT1E12001 looks really, really cool. It is tiny. It could hide behind a quarter. It is a joystick with switched in eight directions, plus a pushbutton, plus a rotation encoder. It may require some electronics to hook it up, but it will be well worth it! -Chuck-

That's a nice article. Interesting ideas begin to form...

I was looking around for some info on this topic and I ran across this site .

Would the circuit for "Up Down detection circuit" work to output the rotation of the encoder into something the keypad input would see as a "button press"

jace055 wrote:I was looking around for some info on this topic and I ran across this site .

Would the circuit for "Up Down detection circuit" work to output the rotation of the encoder into something the keypad input would see as a "button press"

Cool info. Think I will give it a try. But you can hook the encoder up directly. It does work, but it is a bit slow to respond. I think that that is due to the debounce times which I have not had a chance to test. -Chuck-