Gp2x Joystick Exposed - The Internals

[thoro]

...hmm, it might be this component from ALPS:

> RKJXL100401V

There's a PDF - and it looks like GPH mounted it the way ALPS suggests:

 

[0-bake]

I don't know why the switch mfg didn't make the contacts the same size but they didn't kind of dumb. Then GPH didn't know any better so they just threw it in without testing, dumb and dumber.

that is a thing, i cant figure out:
GPH produces this product without having it tested before. although it seems this way
if i ran a company, i would test a product i like to mass produce before mass producing it...

 

[bazuka]

thoro
That looks to be it, but according to the datasheet, the shaft should move 12° in any direction before contact is made. The deadspot on mine seems larger than 24°, but not bu much.

I am going to find a distributor for this and order a couple to mess around with.

 

[Deed]

This is the most serious gp2x's issue after only the lcd's interlacing

It is a joke, right ? Or are you really really not able to push the stick left, right, up and down with enough precision to not hit diagonals ?

Btw, gaming is all about challenge, and master the controls are part of this challenge. I mean, playing snake on my old nokia phone would not have been so much fun if part of the challenge was not to be able to use the phone buttons that were absolutely not intented to play with ...

that said, I agree the joystick manufacture is quite strange. But I'm sure there is a logical explanation

 

[Radek]

This is the most serious gp2x's issue after only the lcd's interlacing

It is a joke, right ? Or are you really really not able to push the stick left, right, up and down with enough precision to not hit diagonals ?

Not, this isn't a joke of any sort. Unless we would call joke a running a game's character with erratic precision.

Yes - I can turn up, down, left and right but making it every time is unreliable. Some games care about it less (methanebross) but some others will give diagonal instead or nothing (like in the Nebulus). To overcome this inprecission I have to push the stick harder but then my thumb my slip from it.

Btw, gaming is all about challenge, and master the controls are part of this challenge. I mean, playing snake on my old nokia phone would not have been so much fun if part of the challenge was not to be able to use the phone buttons that were absolutely not intented to play with ...

Yes it's a challenge and one too much.

that said, I agree the joystick manufacture is quite strange. But I'm sure there is a logical explanation

​

It's fine in that sense it works. But isn't too adapted for arcade games and the diagonal bias is just strange as unnecessary.

 

[Eolair]

My guess is that this is an industrial joystick with diagonal bias. It was never meant for gaming. Unfortunately GPH probably never even informed themselves about the specifications.

Not having the same contact size means the circle of movement is not equally distributed in all directions. Normally if you have 8 directions you will have 45° to each direction. This means that you'll have a good margin of 45° for each action.

Looking at the contacts you can see that the gp2x joystick have a 35/55/35 distribution. Horizontal/vertical directions has 35° each while the diagonals have 55°. This means that while you have a nice wide 55° margin on the diagonals, you'll only have 35° on the verticals/horizontals. They will be much harder to hit.

So while a normal unbiased joystick looks like the one below to the left, the GP2X has one with a diagonal bias that looks like the one to the right:

Unfortunately you can't just desolder the stick, rotate it by 45° and put it back in. The soldering contacts won't line up with the board. GPH really messed up on this one

 

[murak]

Greate work DaveC! Very interesting pics!

Me personaly would like to find a "proper" directional-pad (think NES or MegaDrive) and solder it on the GP2X. The "middle-press-button" could be placed on other location on GP2X chassie. Will look in to it..

 

[pepone]

Knowing this, I wonder if the 2nd case of the "joystick configuration proposal" will attenuate the pb. ??

What do you think?

 

[reaper79]

Personally, I don't think the stick is all THAT bad. It takes some getting used to, and some people are more sensitive than others, but on the whole I don't mine it too much. Remember when you got your GP32? I thought that little stick was absolute shit, and after almost 3 years with my GP32 I wouldn't have the stick any other way.

That aside, I can't believe we have a diagonal bias on the GP2X joystick... WTF??? What amazes me even more is the amount of "dead zone" between the contacts, those are some pretty big gaps from the looks of DaveC's pictures. I'm good at modding things and would like to take a stab at this. If anyone find a good place to order from (where did you get yours DaveC?), please post a link. Or maybe we could do a group order if enough people are interested in playing with it.

 

[DaveC]

...hmm, it might be this component from ALPS:

> RKJXL100401V

There's a PDF - and it looks like GPH mounted it the way ALPS suggests:

​

Yes it is that. strange but the first time I clicked on link it went to the wrong one :blink:

 

[Deed]

You really are whiners. Looking at Eolair's picture, it just makes plain sense. Contacts for left, right, up and down directions are just in the right place and have the good larger. Why the hell should these contacts be more larger than they are ?

Gaming is also all about precision, do you know ? It's just plain sense that if I do not push the joystick right, it will not go into the good direction ! There may be an error margin, but it does not have to be too large ... So 35° is nice enough for the main directions I think.

Btw, dead zones are quite more annoying than this 35°/55° stuff.

 

[gaz]

Playing BombJack in MAME GP2X with 90 degree screen rotation is sweet!

I now know why!

 

[thoro]

Yes it is that. strange but the first time I clicked on link it went to the wrong one

I edited the link - the first one had a (my) session id h34r:.

You really are whiners.

Hehe!

 

[DaveC]

Knowing this, I wonder if the 2nd case of the "joystick configuration proposal" will attenuate the pb. ??

What do you think?

​

Well if you look at case 2 it would actually make the zones even. The problem is that all previous and current d-pads and sticks all have an X,Y bias, they are not even, or diagonal bias.

 

[DijiTao]

We need this image:

Updated with the new information -- should prove inresting (if not depressing)

 

[barnesy]

How plausible would it be to rotate the whole joystick assembly 45 degrees, moving each direction pin around one step? It would take a lot of pin bending to get the pins to match their places on the circuit board, but maybe that's an answer? My first guess is that even if the pins can be bent to the right places, the stick might not be able to sit low enough. I need to take my gp2x apart soon for another reason so I'll have a look then.

 

[Jarska333]

Hey, DaveC, any thoughts on replacing the spring with something less, hum, stiff? How big is it?

The stiffnes has been the main problem for me, not the diagonals. It's so annoying, when in addition to the slippery stick, that I haven't even played much with it, so the diagonal problem hasn't surfaced, so to speak...

Problem with all of these mods is, that I'd nevertheless lose the warranty...

I wonder if RJXT they have would be better, and interchangeable?

 

[Radek]

How plausible would it be to rotate the whole joystick assembly 45 degrees, moving each direction pin around one step? It would take a lot of pin bending to get the pins to match their places on the circuit board, but maybe that's an answer? My first guess is that even if the pins can be bent to the right places, the stick might not be able to sit low enough. I need to take my gp2x apart soon for another reason so I'll have a look then.

​

No - bending isn't an option because it would wear off too fast. If there is some clear space between stick's box and front panel then it would be much better to do an adapter using small piece of pcb. It would make stick stands higher but so what?

We need this image:

Updated with the new information -- should prove inresting (if not depressing)

​

Fortunately it will not be that bad. The "case 2" in this pictures should improve handling significantly. For aplications what are needing just 4 ways the "5" will be perfect. So too much despair is unfounded as some programs (methanebrothers for an example) have already pretty good controls even with this "natural diagonal bias".

 

[0-bake]

edit...oops mistake.

i caan't really see, how the contacts "get contact". what actually is touching these 8 contacts?

edit2: if the contact is made by this round "contactor hat", it would be possible to shorten the bigger contacts with an isolator.

 

[DijiTao]

I'm trying to wrap my head around how two contacts get pushed at the same time -- Also there looks to be a massive natural dead-zone as well --- but playing around with the joystick test app, it doesn't feel at all like these pictures look.

Hmm -- actually... What has never felt right comparing the above image to the actual behavior of the gp2x stick is the assumption that the in-between diagonals have just a big target area as the other directions.

I'm actually thinking things aren't as bad as they look -- after all if the stick works peachy in the test app (except for the damn throw distance) then who cares how exactly it's wired.