Understanding rotary encoders

[Ragtop]

There has always been a lot of confusion surrounding Rotary Encoders, and I'm struggling to make sense of it.

 

What I understand is that a typical rotary encoder (Such as this) will send a button press to either output, depending which way you turn it, per click.

 

Connect each output pin to a digital input and the ground to any common ground. Turn left and input 1 fires, turn right and input 2 fires. Keep turning right and input 2 fires repeatedly.

 

Correct?

 

Assuming the above is indeed correct, I don't understand why there is talk about needing to use a Bodnar board and some kind of software to "interpret" the input. Surely its just seen as a momentary button?

 

All I want to do is connect the rotary encoder to Helios and send each pulse to increment a feature (Tacan freq inc/dec etc). Why would I need some special software to implement this?

 

As it happens, I do own a Bodnar BU0836X so if that is the only way to do it then fine, but I'm just failing to see why it wouldn't simply work as any other button on my Brydling B256A13

[Sokol1_br]

You need a USB controller with specific firmware to "decode" the encoder digital wavelength signal as "button press". Leo Bodnar boards handle encoders (1 for each 2 buttons connections).

 

Conventional boards dont "understand" these wavelength, probable due matrix scanning...

 

For non compatible boards looks like you can use rotary pulse switch - see what the guy say in the left column:

 

http://www.737ng.co.uk/technical.htm

 

http://www.mouser.com/catalog/specsheets/TW-700079.pdf

 

Seems these switch have a cam that press left button only and another that press right button only.

Edited May 9, 2015 by Sokol1_br

[zaelu]

It seems the name is a "hint"... encoder. :)

 

It actually transmits a sort of signal. They are able to transmit more than that and their applications are generally way wider than we are using them in Flight Sims.

 

Mines are transmitting a left-right or right-left signal depending on the direction of the turn. So that renders them useless for direct connection because if I want them assigned to rudder trim lets say... if I turn to the right will transmit left-right and if I turn to the left they will transmit right-left... in either case nothing will happen, right?

 

So I have to connect them through a bodnar board and use a program from him (first one on the following link http://www.leobodnar.com/shop/index.php?main_page=page&id=12 ) and program the board to interpret those pesky signals as just one right press and just one left press and then transmit them as such to the direct input interface

 

edit

 

Sokol1_br sniped me :)

 

but here is a pic with my settings

Edited May 9, 2015 by zaelu

[Hansolo]

Hi Ragtop,

 

You assumption on how e rotary incremental encoder works is not correct and that's why it will not work without the firmware.

 

It doesn't give output 1 when turning one way and output 2 when turning the other way. I does that when you are using the Leo Bodnar firmware or equivilent softwares.

 

In reality the encoder itself is varying the A and B signals as can be seen on the attached picture. And that is why you need software to enterpret which directions you are turing because either way both A and B alters high/low. It the sequence that determines which way.

 

Hope it made any sense.

 

Cheers

Hans

[Ragtop]

Thanks for making that clear everyone.

 

Lucky I have that Bodnar board I guess!

[agrasyuk]

 

Connect each output pin to a digital input and the ground to any common ground. Turn left and input 1 fires, turn right and input 2 fires. Keep turning right and input 2 fires repeatedly.

 

Correct?

 

not really. in a nutshell turn right A then B fires. turn left B then A fires.

sounds like you already figured out what controller you will be using.

[Ragtop]

This is why I love forums. I was half ready to just have a bash at it!

 

Thanks again guys.

[NeoMorph WTH]

The reason the LB board needs to be altered to use an encoder because most encoders use something called "Grey Code" inside to reduce problems with incorrect reading (and yeah, having built cockpits before I've taken a few encoders apart in my time because I wanted to know what is happening).

 

You see when you spin the knob on an encoder fast it can easily get confused. The Leo Bodnar boards I have been the most accurate ones I have come across. If you want to see how hard rotary encoders are, just try wiring one up to an Arduino and looking at the numerous code examples. Some are infinitely better than others and some are really horrendous.

 

But returning to your original post... you are essentially right. Unfortunately to identify which way your are turning the knob starting from any position is what makes rotary encoders so useful... and so frustrating for newbies (I ended up bald lol).

 

Ironically I have found that the Chinese rotary encoders I have gotten off ebay have been really accurate when used with the LB boards. I thought they would drift but they feel good in operation and work flawlessly.

 

 

Just one question... what do you use encoders for in an A-10C cockpit? I'm only just starting out and need to take stock of what encoders, pots, switches and knobs I'm going to need.

Edited May 11, 2015 by NeoMorph WTH

[Ragtop]

I'm intending to use them to alter radio and TACAN/ILS frequencies in the A-10.

 

I don't want to buy a tonne of them so my intention is to get a 3 position toggle switch for the radios and use it to select which radio I'm changing the frequency of. Like a shift state as such.

[Tekkx]

Last post here is almost half a year old. I'll place my question anyway:

 

I intend to complete my HELIOS-dash with some rotarys on HSI, Altimeter...

Thanks to DCS BIOS this shouldn't become a big deal.

 

Now I am spoilt for choice what kind of rotary.

 

There are so many offers that my hair became grey :)

First criterion is size. OK. This is easy.

But:

- what means "absolute" or "incremental"

- which resolution should it be: 20 PPR (pulses per rotation?) or 4000

- there are also "channels" and "detents"

 

Please share your experiences with me. I'm driving crazy!!!

I found some at eby with 18 PPR. Should that work?

 

Thank you so much.