Space Encounters Wiring

[mahuti]

I have a space encounters yoke sitting around with a 270* and a push-pull. Both look like pots (but apparently are not pots) attached to their own boards. One of the boards clearly says "angle encoder. I'm interested in hooking this up, and frankly don't know where to get started. Before I can do anything with them, I'd need to hook up the wiring which isn't super obvious (to me)

I'm sorry if "search is your friend" on this one but as a rookie to driving, steering, analog controls, I don't have a good handle on where to even begin. Before I dive too deep on this set of particular controls (who knows if they still even work) I wondered if anyone had any basic advice or links to get me going.

Any help is greatly appreciated.

Been doing a little research:
http://www.outerworldarcade.com/arcade/space_encounters/space_encounters_encoder.html

http://www.aurcade.com/games/manuals/00000287.pdf

[mahuti]

One more bit of useful stuff. Doesn't say what the signals are... I'm sure digging into the schematics more might tell me something.

[BadMouth]

I've never seen a setup like this before.

My initial impression is that it looks like it functions like a matrix of switches.
Each blank spot on the disc=no signal.
The angle would be determined by the pattern of which fingers (switches) are On or OFF.
This would move in steps and not be useful for other games.

In my electronics noob mind, the leads going to a multiplexer (74153) would seem to confirm that.
I'm interested in learning what the output from the multiplexer is.

I'm busy with work at the moment, but will dig into it later if nobody else does.

Initial impression is that it's cool, but won't be useful for any applications other than the original game.

[mahuti]

Yeah, I looked at that. I agree with your basic assessment.

Due to the low collectibility of this game I'm not too worked up about losing the completeness of these parts (i could probably sell them, or give them to someone that actually needs them) I'm wondering what my options would be to replace these with some other kind of encoder/part to make this yoke useful again.

I love the look of the cabinet, and want to keep it as a basis for a basic driving game cab (swappable panels). It would be cool if this yoke could actually get used again.

[BadMouth]

Well, what size is the shaft?
The gear looks like it would fit right on a pot and the holder also looks like a pot would bolt right in.

[mahuti]

A quick measurement says about 1/4 inch. I could take it apart to get a better measurement, but using tools at hand... 1/4" looks about right.

Like you say, when I first looked at it, I assumed it was a pot due to the way it was mounted. Looks pretty much the same.

[BadMouth]

Having a yoke with a shaft that slides all the way out and then being able to slide one with a steering wheel back in would be really cool.
I'm not sure how to keep the Y axis calibrated, but it would be a cool setup. 

You could have a longer shaft that engages an optical encoder for 360 degree games.
(without the gear that would be required to engage the 270 degree setup)
My mind goes off on all the possibilities. 

[mahuti]

My plan is to attach whatever encoders I need to the directly to the CPO so there's a single USB out, then I can just hot swap the entire CP for different styles of stuff.

I'm slowly setting up all 4 of my machines to be hot swappable, each panel with onboard encoders. Not cheap that way, but hooking them up is so damn simple. The stand-up driving rig won't be able to swap its driving controllers with other machines due to their size and configuration, but it will be able to swap with regular control panels too. That's what I'm ultimately "driving" at.

[BadMouth]

Reading up on the optical version, it seems the tabs around the outside determine the speed and direction like the usual encoder disk, then the other sections determine absolute position.

So there might be a way to wire that thing up to an arduino and translate it into something useful.
But it still only has 16 "slots" around the outside, so very low resolution.

[Howard_Casto]

The old racing encoder boards for Atari 2600 paddles use this method.  Looking up how stella handles these might give you a clue as to what you need interface wise. 

[mahuti]

So there might be a way to wire that thing up to an arduino and translate it into something useful. But it still only has 16 "slots" around the outside, so very low resolution.

Yeah, when I saw the swiper setup that's kind of what I was thinking

The old racing encoder boards for Atari 2600 paddles use this method.  Looking up how stella handles these might give you a clue as to what you need interface wise.

That's good info. Thanks for that. I have half a mind to pull these out while I do something more useful with the yoke... yet still see if I can make these work on their own just out of morbid curiosity.

[PL1]

As Howard points out, this is indeed like the Atari 2600 Driving controller. (related info here)



It uses Gray code which is similar to binary, with the main difference being that in Gray code only one bit changes per step.

    Binary (2-bit)
0  0  = 0 (decimal) - Starting point
0  1  = 1 - 1 bit changes
1  0  = 2 - 2 bits change ***
1  1  = 3 - 1 bit changes
0  0  = 0 - 2 bits change ***
. . .

    Gray code (2-bit)
0  0  = 0 (decimal) - Starting point
0  1  = 1 - 1 bit changes
1  1  = 3 - 1 bit changes
1  0  = 2 - 1 bit changes
0  0  = 0 - 1 bit changes
. . .

Space Encounters uses 6 bits (64 possible positions per rotation) of an 8-bit Gray code positon encoder (256 possible positions per rotation) for both the X-axis and Y-axis.

Wikipedia has code samples here for converting between Gray code and binary if you want to hook your position encoders up to an Arduino to make a HID device.


Scott
EDIT: It is an 8-bit position encoder wheel that only uses the 6 Least Significant Bits.

[BadMouth]

Given further thought, the gearing looks like a pretty high ratio, so it might be more usable than the 16 count encoder wheel would suggest.

I'd enjoy figuring this out if I had more free time...but I don't right now.

EDIT:   Never mind.  I should have read PL1's post more completely before posting.

[PL1]

Upon further examination, it appears that the Space Encounters has an 8-bit Gray code position encoder wheel (256 possible positions per rotation) but only uses the 6 least significant bits.

This is similar to the Atari Driving controller which has a 4-bit poition encoder wheel but only uses the 2 least significant bits.

There are 8 arms that can make contact -- the wheel only has metal on one side so the 8 arms on the other side do not make electrical contact.



Since none of the 8 arms make contact with metal all the way around, it appears that ground comes from the center-hub.

I verified this by using a photo of the position encoder wheel, superimposing a partly transparent strip from a photo of the contact arms, and overlaying circles on the contact arm rub-marks.

You can see the 8 contact arm paths -- red for the 4 on the right, green for the 4 on the left.


Scott