Gp2x With External Screen Via Tv-out


bacteria

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Bought a PSone screen a while back (good old E-bay!), butchered it apart (my new Dremmel from E-bay is great!), hot wired the 5v bypass (so only needs one set of batteries), stripped off all the cable connections and it works fine with tv out via the GP2x (using the old tv out cable) as composite video input. (thanks go to BenHeck forum!). Looks a bit like a roadkill, but works fine!

One issue; connected this 5" PSone screen to an old N64 I have, visuals are very nice, crisp and great. Did same on GP2x, and although it is quite good, there is some flicker (minor, but annoying). Also, the text is rather blurry, and when going to the GP2x menu (Ryo's) the text flickers, the colours flicker/scroll a bit - almost like the refresh rate is not good. I know it is not the PSone or connections as it is good on the N64 as a mobile screen.

I have bought a better quality Svideo male to composite male cable from E-bay incase it improves the quality.

Question is this: is this a fault with the GP2x output (ie crap basically), or does it need connectivity to s-video to remove the problems, is there anything which can be done to improve text quality, colour accuracy and flicker (eg a transistor, etc)?

What I am hoping to achieve, if I can, is a rebuild of my old project, using a SNES arcade controller (to be butchered), a D-pad (butchered from either a NES contoller, N64 controller or Nintendo gameboy mini (keyring)), 10,000NiMH (or close to) C or D cell batteries. I would also place the PSone screen on a rotating plate so it can be vertical or horizontal (good for some shoot-em-ups from MAME). It could look a bit like an old retro tabletop arcade game potentially (there would be plenty of spaces for the electronics inside the casing).

Interestingly, some games like Mame play on the PSone screen nice and fully, some games like (the excellent) Blingo miss a bit off the right side of the screen. Anything I can do to keep things as they should be?

If I can't be happy with the output via the GP2x, ie get a better result than now, there probably won't be much point in extending the project. I got one of those add-on units for an old GBA which gave tv-out; I could hack away at this I suppose and make a large screen hacked GBA unit I suppose! (I would rather do the GP2x mod though!

Anyone got ideas or comments please to improve the tv-out quality on the GP2x?
 

sehs33

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Hey bacteria, your problem seems to be software dependent, you can try the latest version of GMenu2x, or maybe give the TV out fixer app a try with the applications you use.
Good luck in your project :)
 

bacteria

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I am using Firmware 2.1

Games like Wolfenstein might not work on latest firmware (?) so stayed with what I know. Do the latest firmwares do anything to address the issues I mentioned earlier?

Using the latest version of GMenu2x.

Sehs33 - thanks for reply - not tried the TV out fixer, what is your experience of it; what improvements does it yield?
 

bacteria

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I spent years avoiding E-bay, I got swayed when I wanted a PSone screen (can't buy one anywhere else easily); read up about E-bay and how to protect yourself, and not looked back. Been doing it since December, got a 100% rating with over 260 feedbacks so far (so I must be doing something right!).

I'm not an advert for E-bay, but it is a really good way to buy things very cheaply (if you are vigilant!) - mind you there are a lot of idiots who bid on a broken GP2x recently and paid more for it than a new, guaranteed one. Muppets!

Anyway, "The MASTER" - any comment to add on this flicky screen issue please?? I want the screen from tv-out on GP2x to be at least as good as from the output from my other console outputs! I would rather do a great GP2x mod than a GBA one!!
 

yodaofborg

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Could be a low quality/bad cable connection too, so I would at least try another cable. Also, AFAIK, the GP2X outputs in S-Video, not composite, you can hack the RGB signal together to create a kind of composite signal, but it will never be as clear as a S-Video connection, does the PS-One screen not have RGB inputs?
 

Squidge

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The MASTER said:
Are you really an advert for eBay? ;)
I was about the write the exact same response :)

Anyway, if you use the original GPH provided menu, what happens to the screen output when you adjust the refresh rate? It certainly sounds clock-related to me.
 
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bacteria

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yodaofborg said:
Could be a low quality/bad cable connection too, so I would at least try another cable. Also, AFAIK, the GP2X outputs in S-Video, not composite, you can hack the RGB signal together to create a kind of composite signal, but it will never be as clear as a S-Video connection, does the PS-One screen not have RGB inputs?
Yes, the PSone can take RGB inputs as far as I know, but to he honest I had two tv-out cables for the GP2x, so I cut one up and saw it had a black, red and green cable, and a fourth bare-wire one. I couldn't fathom out how to connect them to the PSone :huh: - perhaps someone could tell me which one goes where? I spent hours yesterday looking on BenHeck, a lot of it is quite technical... :huh:

Image of this from BenHeck forums (thanks to them) is:

gba3ej4.jpg


Can't get the audio to work, but I know a workaround - I can just take the wires from the speakers to the PSone's. Used an s-video > composite converter - hopefully the new one I have bought today will be even better picture quality.

I hooked up the PSone screen to my old, battered GBA (with tv out add-on), removed the screen from the GBA, it only takes composite input, screen image is actually quite good - to be near perfect it would need to be slightly less red, but pretty good!

To show the GBA rig working, playing Super Mario Ball:

gba1op9.jpg


and...

gba2wj9.jpg


White wire under the PSone screen feeds from one of the pins to a chip at the back of the board which in effect saves using further batteries (the PSone needs 7.5v to work, and 5v for the screen to boot (this wire takes away the need for the 5v extra).

Not all the bits on the picture are relevant, just a few bits I was playing with.

A nice WIP, yes? ;) As you can see, the button contacts are nice and easy to connect to and nicely exposed!

These PSone screens are nice, anyone know of an even better one??

Waiting to get my new (better?) s-video > composite cable (unless anyone can confirm s-video connections to the PSone screen perhaps? and (here we go again :rolleyes: ) a new soldering iron from E-bay - paid under £8 for a solder, with desolder pump, sponge, (delivered) - my old one is knackered.

I am quite impressed with the GBA project, I might have to buy another PSone screen for the GP2x.... :lol:

To make the GBA project have enough power, it needs: 7.5v for the PSone screen (although I might do the white LED mod to reduce this power), 7.5v for the GBA tv-out and 3v for the GBA itself. Might be a way to reduce this lot down...

@Squidge - yes, it does sound clock related. Put project away for day, will play with this later (when my new cable arrives and I need to test it). Hmm.

Please keep your thoughts and assistance coming... ;)
 
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Samba Pa Ti

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wow i remember you talking about the psone screen a while back and now you have it working (very cool) the flickering is very strange but i experience similar flickers via tvout (to a tv) when im doing anything on the 2x if the volume is too high.

using the mp3 player i can turn the volume to about 50/60% and it stops flickering (sounds like somthing is interfering somwhere), im sure theres a way to put a filter capacitor or somthing on one of these wires to remove this bloody flicker at high volume,
im not sure if this is the problem you are experiencing (just thought i would mention it).

also a seperate issue i have, the speakers in the 2x dont go off when i plug in the ext connector, i have tried the speaker toggle program (it doesnt work with the ext properly), it just seems to turn off the sound completely regarding the ext connection.
 

bacteria

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Samba Pa Ti said:
wow i remember you talking about the psone screen a while back and now you have it working (very cool) the flickering is very strange but i experience similar flickers via tvout (to a tv) when im doing anything on the 2x if the volume is too high.

using the mp3 player i can turn the volume to about 50/60% and it stops flickering (sounds like somthing is interfering somwhere), im sure theres a way to put a filter capacitor or somthing on one of these wires to remove this bloody flicker at high volume,
im not sure if this is the problem you are experiencing (just thought i would mention it).

also a seperate issue i have, the speakers in the 2x dont go off when i plug in the ext connector, i have tried the speaker toggle program (it doesnt work with the ext properly), it just seems to turn off the sound completely regarding the ext connection.
Interesting...

I find with the tv-out cable, that the GP2x internal speakers stay on, strange. Planning to cut their wires and connect longer wires to the PSone speakers; saves the problem. Not played with the PSone speakers yet, but they are bigger and have to be better than the GP2x ones! ;)
 
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sehs33

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I don't know, but maybe if you pulled the sound from the headphone port this will solve it? you will only need a 3.5 to stereo audio cable.
 

DaveC

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bacteria said:
Question is this: is this a fault with the GP2x output (ie crap basically), or does it need connectivity to s-video to remove the problems, is there anything which can be done to improve text quality, colour accuracy and flicker (eg a transistor, etc)?

Well you do know that composite is basically the worst quality signal you can get other than RF. In itself composite is bleedy, fuzzy, has poor color separation/saturation and is full of dot-crawl and noise , and that is on a good day. Even if the cables are perfect it will look rubbish. If you can get S-video to the PS1 screen it will look a bit better. If you can connect both through RGB then it will be best and will look close to the quality of the GP2X screen itself if the native res is the same. The other thing is I don't know what the native resolution of that PS1 screen is. If it doesn't match the GP2X you will get fuzzyness from that too.

Using that screen as is the image will just look "overcooked". You are taking the GP2X signal, modulating and combining signals then sending it to the screen hardware which takes that modulated signal and tries to separate the signals back again. It is done analog so the quality will degrade at every step. It is just too much electronics to go through to get a clean image.
 
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bacteria

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DaveC - thanks for reply.

PSone screen is 640 x 480; so 1 pixel on the GP2x would be 4 on the PSone screen. Not really an issue - after all most emulated games were always a little blocky!!

Take your point on the composite; I know the GP2x outputs S-video (via the tv-out cable) and you can of course convert S-video to composite with an adaptor (as I used).

The PSone screen can take RGB, but I don't know if the GP2x can output in RGB - can it?, if so, any chance you could elaborate as to how please (ie what the pins are to connect to, and any advice about it please)?? If it can use RGB, would only a quarter of the PSone screen be used or would it fill the screen properly (1 pixel = 4)?

The picture from the GBA (or N64)to the PSone screen (as per my pic) is pretty good, a bit on the red side, but pretty good; noticeably better than on the GP2x. Would S-video cure the colour balances and crispen the image compared to composite?

The S-video cable - 4 wires (from the GP2x tv-out cable) - red, green, black and bare wire - which wire does what please?? I might be able to hook up S-video on the PSone if I knew more about these wires! :huh:

Advice appreciated! :rolleyes:
 

Orkie

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bacteria said:
The S-video cable - 4 wires (from the GP2x tv-out cable) - red, green, black and bare wire - which wire does what please?? I might be able to hook up S-video on the PSone if I knew more about these wires! :huh:
http://pinouts.ru/Video/SVideo_pinout.shtml

DaveC is wrong in saying s-video will look a 'bit' better than composite, it is much higher quality. Also, just because the PS1 screen is 640x480 doesn't mean the image will just be scaled evenly in both directions. The GP2X *only* outputs TV resolution, it won't do 640x480. This means that whatever you do, the output will look a bit stretched and not very nice.
 
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Orkie

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Samba Pa Ti said:
is the ps1 screen 640x480 ?

it should look ok if its designed to work with consoles which work on tv shouldnt it ?
My point was that the GP2X itself outputs a stretched image, and no solution to this has yet been found.
 
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bacteria

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Orkie said:
bacteria said:
The S-video cable - 4 wires (from the GP2x tv-out cable) - red, green, black and bare wire - which wire does what please?? I might be able to hook up S-video on the PSone if I knew more about these wires! :huh:
http://pinouts.ru/Video/SVideo_pinout.shtml

DaveC is wrong in saying s-video will look a 'bit' better than composite, it is much higher quality. Also, just because the PS1 screen is 640x480 doesn't mean the image will just be scaled evenly in both directions. The GP2X *only* outputs TV resolution, it won't do 640x480. This means that whatever you do, the output will look a bit stretched and not very nice.


Ok, so based on the PSone connections diagram, which of the s-video wires go where please (black, red, green and bare wire (I cant open that part of the cable and find out)? Can the GP2x do RGB (the PSone shows the connections for RGB)? :blink:
 
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DaveC

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bacteria said:
Ok, so based on the PSone connections diagram, which of the s-video wires go where please (black, red, green and bare wire (I cant open that part of the cable and find out)? Can the GP2x do RGB (the PSone shows the connections for RGB)? :blink:
The GP2X is doing RGB now when it displays to it's own screen. Interfacing that to the PS1 screen and getting the timings and 2:1 res would be rather difficult without a custom board. It would be possible but would take alot. The MMSP 2 chip does have an RGB out too but I doubt it has the power to drive a screen, you would have to make some kind of an amp.
 
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