Touch Screen X-y Swapped?


Still Fresh
May 19, 2008
So I've got myself a nice new GP2x F200 unit. It came shipped with 4.0.2 (which was an issue in itself, but now is on 4.1.0) now I can actually callibrate the touch-screen in english, I know for sure it's not working right. It calibrates fine, and even moves the pointer perfectly on the final calibration screen. ..but in every game, it's entirely wrong.

In everything I've tried: ScummVM, FlipIR, Exult, Tile World, FPaint, etc. touching with the stylus the x and y axis seem to be swapped. ie: I touch the top of screen, pointer moves to the right side .. bottom of screen, pointer moves to left. Touch the left side of the screen, pointer moves to the bottom, right side, pointer moves to the top. :|

It feels to me like the touch screen cables have been wired wrong, so the x co-ords are plugged into the y on the motherboard input and vice versa. Anyone know the internals of the machine to know if this is possible? Could it be just software/firmware? Or is it serious enough I should just return it. (I'm tempted to take it apart to try to fix .. but it is brand new.) :unsure:
It's probably related to the LCD change that EvilDragon mentioned in this thread. Sounds like someone needs to do some investigating so devs can recompile all of their software <_<
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fishybawb said:
It's probably related to the LCD change that EvilDragon mentioned in this thread. Sounds like someone needs to do some investigating so devs can recompile all of their software <_<

By the sounds of it, virtually everything is going to have to be recompiled. Even SDL etc. would need changes to take account of this (and by the looks of it, we're talking hideous "If Firmware_version = X or LCD_Type = Y then do Z, else...." changes throughout). And then any program that statically links against SDL (i.e. most of them) would need a recompile against the new lib with all that junk in it. Similarly for Allegro, hand-coded, etc. programs.

From what I gleaned from that other post, the new type of screen either reports presses backwards or the screen displays things backwards, which means that you can't really "fix" that, you just have to work around it. And if you design for the new screen, F-200's with the old screen would show similar problems.

Roll on the days of a TRULY open games platform, without massive undocumented changes, and where the source code is available in roughly the same year as the release of the firmware so that people can see what bloody changed. Seriously, anyone found the source code to F-100 version 3 firmware yet?
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A similar thing happened back in the GP32 days - Gamepark changed the screen that the backlit (BLU) model used, omitting to mention that it wasn't entirely compatible with the old one. The new model was dubbed BLU+, and devs either had to add a "BLU+" option into their menus to avoid the display looking b0rked, or compile specific binaries for each model.

In short, an almighty fuck up. I really hope there's still enough interest in the GP2X for people to be bothered updating stuff for owners of the newer model F200...
Sphinxter said:
Sure it's not just 4.1.0? I mean did it work right before you flashed it when it was running 4.0.2? Not a big bonus calibrating in english.
No, it wasn't 4.1.0 .. it was doing this in 4.0.2 (which is how it shipped from From what I've been reading it's all due to the new LCD unit in the F200 models.

..and, now that I've stopped panicking and done more thorough troubleshooting, I realise the touchscreen itself is fine. In the post-calibration screen the pointer follows my stylus perfectly (Nintendo DS stylus .. throw out those GPH ones guys .. they're crap, inaccurate, and can scratch the screen) and all the internal apps use the touch-screen perfectly.

It looks like coders are going to have to account for this new touch-screen explicitly. Have an option to transpose the x and y detection. Dont-cha love 'progress'? :D
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I'm getting the same thing, new F200 owner, came shipped with 4.0.2 and a seemingly backwards touch screen. At least 4.1.0 has fixed some of the other compatability issues, REminiscence works now :)

I'm no coder, but couldn't a small app be written to stay in memory and swap the x and y axis over?