Bacteria's project - Modding a GP2x....FINISHED

bacteria · Post by **bacteria** » Mon Dec 03, 2007 4:07 am

Just spent about an hour playing various games on the GP2x via the PSone screen, just to see what the quality is like.

I seemed to have improved the picture a bit by making it stable by changing the 220pu capacitor for a 470pu one on the chroma line. I tried putting a capacitor on the luma line but it didn't make any difference, so I removed it.

The PSone screens are good after all, but not jaw dropping. This s-video input hack works well, images are nice.

I had thought that I needed the tv out hack program from rlyeh on the GP2x forum, but frankly, outputting to a PSone screen with its 640x480 resolution (the GP2x is 320x240) is absolutely fine, as it should be after all, one pixel on the GP2x = four on the PSone screen. I think it fair to say his program, if/when he finished it, may actually not make much difference ultimately to this project, which is good news. At this resolution the GP2x built-in tv out is fine.

I see no point in making the PSone screen rotate anymore, its only a handful of MAME games which would benefit, but it would mean lots of switches to divert controllers and a slightly bigger system case and less good looks; it is easier, and makes more sense, to do as you do on the GP2x; turn the system round and use the volume buttons on the GP2x as the action buttons. Saves hassle.

I have a few days this week to crack on with the case, in preparation for the damaged GP2x I am getting from Australia; by the time I am ready for it it should be here hopefully.

I am thinking about making the case look a bit like the Ipaq PDA project in a way, I like the way the sides are smooth and look like a solid case, if I make the corners angular (like my Nintendo 64 Advance project) I think I can make the corners virtually seamless potentially.

After this project, it will be time to make a better, flatter, sleeker and prettier N64p; this time with batteries, side loading cart (yes, a side loading cart), a TI board and Expansion Pack (I hope, all goes well!). My skills are developing quickly in this modding work now.

bacteria · Post by **bacteria** » Mon Dec 03, 2007 4:22 pm

I wanted to get rid of all the old clutter wires from my old soldering and taping (not a very clean job before). I removed the PSone plugs and soldered wires directly to the connectors. Accurate soldering required!! No wire is shorting to its neighbours, all checked. I wired up three grounds, I know I only need one (ground is ground), however it makes things tidy. I will use one ground for the chroma, one for the luma and the other one for connecting ground to ground from the PSone mobo to the GP2x ground. I am using a red and black wire I got from an old USB cable, nice and flexible and reasonably thick.

I made a note of the two main wires for the s-video, the chroma and luma, so I can trace them back to the GP2x when it arrives and hook it up. I also decided to have the option of headphones, so I used my multimeter to ascertain which wires connected to what - left, right and headphone ground. I put an old headphone connector onto BluTak to hold it in place while soldering:

I then held the wires in place with pliers and bent the wires over the back of the PSone mobo, and hot glued them in place so they don't tug out. This pic also shows the 470pf capacitor I am now using (which I removed off an old dead mobo from something or other). The capacitor has some electrical tape under it to stop a short, and the capacitor is hot glued in place to stop it detaching.

This is about as neat as I can make it. More space and less clutter means it is easier to install and fit the other components better!

More updates tomorrow.

bacteria · Post by **bacteria** » Tue Dec 04, 2007 4:26 am

I made a decision. Each project needs a twist to stave away mediocrity.

As I have tidied the PSone connection wires from being the usual jumble, I decided to have a go at making the rotating screen as indicated before. The screen and screen mobo can freely rotate now.

I re-worked the drawing, all fine, lots of space on the sides for the digital joystick and buttons under, and buttons on the opposite side.

If I can rig it up so turning the PSone screen breaks one set of switches and opens another, that would be ideal. in MAME on the GP2x, you can rotate the screen to play games like Gorf, Galaga, PacMan, Phoenix and all other old arcade games designed to play portrait rather than landscape. When you select this mode, the controls change from the standard D-pad and A, B buttons to D-pad (rotated so right=up, etc) and the two volume controls on the GP2x become the A and B buttons. This means a total of 6 switches (3 switch, double pole switches) otherwise. It would be nice to do this feature, I do love these old style games!

I also need to be creative in designing a case with a rotating facility, and keeping it looking nice. I will need to secure the section under and on top for rotation. This means two top layers, which is fine as I intend to make a wrap-around cover case like I did on the PDA. If I hadn't had worked out how to do this on the PDA, I would have had problems with this design.

New case design:

Dimensions are (the pencil line): 232mm (so 240mm when done) by 197mm (205mm). Not noticeably any difference in size; but this is as small as it goes when using C cells and 55mm speakers!

bacteria · Post by **bacteria** » Tue Dec 04, 2007 5:39 am

Here are some of the games which benefit from being portrait:

PacMan (Ms PacMan, etc)

Phoenix

StarForce

Galaga

Of course there are several others: Gorf, Dig Dug, Dig Dug 2, Donkey Dong (and follow-ups), 1942, Arkanoid, Commando....

There are of course many quality games which are landscape, playable on the GP2x, like the Metal Slug series, Neo Turf Masters, Bomberman, etc (NeoGeo); SMS, NeoGeo Pocket, Megadrive, NES and SNES games, etc: however when you just want a quick-fix game, the old arcade games are excellent! The GP2x is also great for MP3 playing and also movies too.

tom61 · Post by **tom61** » Tue Dec 04, 2007 6:34 pm

You should definitely make it rotatable. Because A) It's cool. B) I want you to figure it out in case I decide to make an emulator portable with a PSOne screen.

bacteria wrote:I had thought that I needed the tv out hack program from rlyeh on the GP2x forum, but frankly, outputting to a PSone screen with its 640x480 resolution (the GP2x is 320x240) is absolutely fine, as it should be after all, one pixel on the GP2x = four on the PSone screen.

Actually, the LCD in the PSOne screen is 320x240. One to one ratio with the GP2X. No idea why 640x480 keeps coming up as being it's resolution, but anything higher than 320x240 is interlaced. Look up the datasheet if you are in doubt.

bacteria · Post by **bacteria** » Wed Dec 05, 2007 3:59 am

tom61 - I Googled about the PSone screen resolution, to try and get a definitive answer, couldn't find a datasheet (any chance you could post a link please so I can look)?

I found this project, he claims the higher resolution on his specs, and on page 2 of his project it shows 640x480 setting up the screen to work via VGA on his computer. http://www.bit-tech.net/modding/2004/07/07/psone_lcd/1

It would be nice to know the definite answer. I looked in the PSone screen manual and it doesn't even mention the resolution of the screen there.

This rotation of the screen is an interesting puzzle; you don't want a handle or bar to move the screen from one orientation to another as you would have a 90 degree hole in your case; be it at the back or side, or an eyesore of a knob/handle on the front for gripping and rotating. This isn't acceptable. I want ideally to have a smooth surface which you rotate by the pressure of your fingertips.

To make the rotation possible, you need to have a sandwich. Top layer holds the perspex in place, perspex in middle (strength, and a clear top for the PSone screen to keep it protected), bottom layer to hold perspex in place.

The accuracy of the cut of the perspex is not important, as long as it rotates freely. The top and bottom layer need to be fairly perfect circles to allow the assembly to rotate and not slip or stick or move about.

Thus, I could cut out the perspex crudely with a drill, as the gap between the two pieces isn't important, which is just as well as it looks crude. This will be invisible in the end (apart from the area in the middle the screen will go), so not relevant.

This is why using the concept I used for the PDA will work great with this project. You will see as this project develops, why.

bacteria · Post by **bacteria** » Wed Dec 05, 2007 7:15 am

Soldered wires to the PSone contrast and volume buttons. Hot glued these wires to the edge of the PSone screen and top of mobo, these wires will move with the PSone screen when the screen is rotated, so I don't want them to wriggle free.

I had to cut out a slightly larger circle from perspex (another sheet), as I hadn't allowed enough clearance for the "sandwich". The PSone screen, corner to corner, is about 150mm long, so I made the circle about 170mm.

I gave the perspex a good clean with PC LCD screen cleaner; and hot glued it in the corners to the screen.

I need to check the size of the case again, it might be that this "extra" means I need to increase the case size by a few millimeters, or may not, I need to ascertain this before I cut it to size.

bacteria · Post by **bacteria** » Wed Dec 05, 2007 9:21 am

Yes, had to make it slightly bigger - pencil drawing underneath were original sizes. The perspex is at right angles, the drawing isn't. Size is now 240mm x 210mm (so will end up 248 x 218mm). I needed to make this a little bigger than originally planned as the screen circle cutout needs it tracks in place (the sandwich), if I cram things in too much I would end up compromising on the durability of this feature.

The tact buttons, speakers and batteries are placed in position, to give an idea how it will fit. I preferred having the batteries more balanced, this is the best I can get; they are rather large after all.

The red circle on the left is the cutout for the digital joystick. The buttons on the right are (top to bottom): Y, X, A, B. B is the main action button, A is the next, X and Y are more used for options. At the bottom middle are 6 buttons (only 4 shown), two 12mm tact switches for Select and Start; and 4 x 6mm tact switches directly above. To explain, many emulators on the GP2x use key combinations to exit to a menu or exit the emulator back to the system menu. Typically this is left shoulder + right shoulder + start; or vol+ + vol- or whatever. To this end, I am making two of the four small tact switches the two volume controls (not the PSone volume buttons I add, these will be mounted elsewhere) and the other two for the shoulder buttons; this will make it easy to access the functions without contorting fingers to get to them normally!

I don't need to place the GP2x vol+ and vol- buttons near the joystick to act as action buttons (they become action buttons when you normally rotate the GP2x to play vertical games), as I will reallocate them to the A and B buttons, so normal play happens.

I am going to have to work out the placement of metal contacts for when the screen rotates, to switch button actions and joystick control changes.

bacteria · Post by **bacteria** » Wed Dec 05, 2007 10:10 am

I have now cut out the perspex with my dremel.

I discovered on my PDA project that there is no loss of sound quality by having a thick piece of paper/thin card (160gsm) over the speaker holes; so i decided to use this principle on this project. I can't have big speaker holes in the case otherwise it will make that part of the case weak, also I need to bore holes in the perspex for the speaker (just not the top bit with the paper on top). I thus drilled holes over the speaker areas to make big holes but keep the perspex strength. The joystick is cut out, nice and circular and smooth, and the holes for the tact buttons are done.

As the only thing needing accuracy is the joystick, I have managed to cut the holes quickly (see time lines of my postings). Any finishing will be done with the mounting card on top (perspex, mounting board on top, paper on top - as per PDA project).

bacteria · Post by **bacteria** » Wed Dec 05, 2007 10:20 am

Ignore all the stuff under the perspex, this is to give an idea of what it will look like (if you have imagination).

I need to get the vacuum cleaner out, LOTS of bits of plastic on my floor at the moment!

Picture makes it look bigger than it is, I can assure you! When holding the case, my fingers and side of my palm cover a reasonable area of the case.

Back to project tomorrow.

tom61 · Post by **tom61** » Wed Dec 05, 2007 4:53 pm

bacteria wrote:tom61 - I Googled about the PSone screen resolution, to try and get a definitive answer, couldn't find a datasheet (any chance you could post a link please so I can look)?

I found this project, he claims the higher resolution on his specs, and on page 2 of his project it shows 640x480 setting up the screen to work via VGA on his computer. http://www.bit-tech.net/modding/2004/07/07/psone_lcd/1

It would be nice to know the definite answer. I looked in the PSone screen manual and it doesn't even mention the resolution of the screen there.

Get the numbers and make off the back of the LCD unit itself and google the datasheet for that. I was rather disappointed with the 320x240 native resolution of LCD during my attempted PCp project.

That 640x480 mentioned in the article is interlaced, it's displaying lines alternating over the same row. Which is why you'll find issues with text 'flickering' on projects running "VGA mods" on these. It's like displaying high-res stuff on a TV. A TV doesn't have 800 by 600 lines of resolution, but it can cheat a little by interlacing, and you get a fuzzy picture of the output.

arfink · Post by **arfink** » Wed Dec 05, 2007 7:41 pm

Looks great, I can't beleive some of the awesome things you've been thinking up. I was thinking of getting a gp2x, but I would never have thought to gut the thing, let alone improve it. Looks great, and good luck on the screen rotation. I know it's a bugger to do screen rotation in full size arcade machines, where there is even lots of room for wires. If you can make it work I will be extremely impressed. BTW, is this going to be a foam covered deal like your PDA? If it is, could you maybe cover your technique in more detail, I thought that was intriguing but I could not quite figure out how you did it.

khaag · Post by **khaag** » Thu Dec 06, 2007 12:44 am

This is looking good so far... but the problem I see is the shape of the case. It looks too "square". Looks somewhat uncomfortable to hold. Are you going to add more to the case design or is that it?

(Great work so far though

)

Website · Post by **Life of Brian** » Thu Dec 06, 2007 1:13 am

The rotating screen idea is great! I love it! Well, thanks a lot - I really want a GP2x now

bacteria · Post by **bacteria** » Thu Dec 06, 2007 3:40 am

tom61 - Oh well, it explains the slight fuzzyness. Any way the "interlacing" can be disabled on the PSone screen and just give its native resolution then?

I had noticed that the screen seems to flash a couple of lines at the top of the LCD and the bottom, I planned on covering this with my window on the case, then it isn't distracting when a bright colour is shown as the flashing line won't be visible. This must be the interlacing you refer too. Do any of the 5" (or thereabouts sized) screens out there suitable for modding projects give an absolutely steady picture with no interlacing??

arfink - The GP2x is a very good games system; it runs almost all games on the Megadrive, NES, NeoGeo, old MAME games, GB, GBC and (I just discovered) GBA games at or close to fullspeed; some SNES games, but a bit slower. Yes, GBA too - I hadn't tried this emulator on the GP2x before, amazing! It also plays movies and music files. You can overclock the unit from its native 200Mhz to around 260-300Mhz (depending on luck and the unit you have), which helps playing the games fullspeed.

I hate squinting at a small screen, a 3" screen doesn't cut it for me, that's why I am using a PSone screen, I find looking at a tiny screen very tiring on the eyes, which is why I can only play games on my DS for short periods.

My design for the screen rotation is simple (simpler the better), however I may need to hack a bit here and there from the "sandwich" to make it rotate easily. I had considered, and dismissed, a handle or stick; and not using cogs as these are destined to fail. I also decided against making indents in the case for fingers to fit into to turn the screen as this can only look ugly. I am however taking advantage of the fact that the screen is not square, so there is plenty of surface area to lightly press above and below the screen and rotate the screen. Neat! I am toying with whether I make a design feature of the rotation circle by putting a circle around it, and mini circles as design features on the casing to make it look "chic"; or make the rotation circle as transparent as I can.

I bought some arty paper, 160gsm, speckled grey in colour, as it looks nice and is forgiving to blemishes and finger marks, I will use this for the outer casing.

Yes, the buttons will be made in a similar manner to how I made the PDA ones, they work great and are steadfast (especially when a small amount of clear varnish is applied to the foam sides). Yes, ok, I will be happy to cover this in more detail on my guide, no problem.

khaag - Yes, I agree, you don't want sharp corners, although this would make it easier to make the finishing to the case. Sharp corners are not great for design and not comfortable to use for a case. I had thought to angle the corners (like on the Nintendo 64 Advance project), however I have a much better idea - I am going to use the tops off bath foam bottles, they are quite rigid (I can reinforce them anyway), straight and quite thin. (My Blue Peter part of my logo is coming into play again!!). I had thought about toilet roll tubes but they are a bit large and the finish isn't good enough; smooth plastic is better, and these bottle tops are ideal!

If I paint them black, they will be a design feature of the system and also give circular corners: also this will be far easier to cover the paper top around and bypass the plastic corners. Watch this evolve!! The contrast between the speckled paper and the black will look nice.

Life of Brian - Thanks, there are good reasons to have a rotating screen on this project, and it is a far more interesting concept than making the system in a standard manner - much more of a challenge this way! (and a first). You can get GP2x's at a good price at the moment, on e-bay. Go for a MKII version if you can, although there is nothing wrong with MKI (but don't bother with "first edition", they had some issue with them.

I have a few chores to do around the house now, then I will have some time to do some more on this project. When I go grocery shopping later I will need to buy more of the bath foam, for the lids - I need 3 more for this project!