Finding Rgb Lines On The Gp2x


bacteria

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Once I have finished my N64/GBA project, I thought this would be a good project:

I have a GP2x, nice little system, especially for emulation, however the screen is small, buttons not in good places, and bad control system (you can easily replace the joystick with a D-pad, not difficult, but that doesn't solve the other issues with the system).

TV output from the GP2x is bad, it gives 320x240 output via RGB to its own LCD, but outputs in a different resolution, something like 320x228 or whatever, so lines are missed and it looks a bit wierd: also tv out quality is bad. You can output via S-video, but there isn't a lot of point as the system skips lines on the output. Also, as if this isn't bad enough, the colours are washed out (at least with PAL, NTSC isn't so bad apparently).

Here is the question: how would I be able to trace the lines from the chip or traces to find out which points to solder wires to for the RGB, C-sync and ground? If the answer is "with a multimeter", what readings so I look for, and what do I get my multimeter to look for please?

My thoughts are that if I can get this RGB, then one of two things will happen: either the PSone screen will take the 320x240 and make it fullscreen (640x480), as it tends to do, or just show a quarter sized screen (320x240), I won't know until I try it. If it is fullscreen, proper RGB, this system will be worth making a proper case project for!!

Any ideas guys? - I know there has to be a way to do this investigation, after all, it will be the same type of probing I would have thought as other people have used when locating the RGB connections on other games systems.
 
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Well, I doubt that you would be albe to find the lines with a multimeter. :) Plus, the MMSP2 has a lot of pins. There should be a pin out somewhere... There is this, but you'd need to mash all the R/G/B bits together, and convert them to analog. (I think, I'm not completely sure.) (P.S. Here's the post I stole it from.) Also, check out page 15 of this document. There's some great stuff on that Wiki page that you should check out.

Best of luck!
 
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bacteria

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Thanks for the work, rememberthe8bit, appreciated. I'm not very good at reading these types of documents, but unless anyone can provide a pic with "pin x is red, pin y is green" etc I might have to do what I can with the data.

By "mash all the R/G/B bits together" do you mean solder all the Reds together, etc, into one line? I need to end up with one R one G and one B line as well as C-sync and the Ground. This is what the PSone LCD screen takes.

The GP2x screen is 320x240, I am just trying to tap into this, as the tv out option is awful and not an option in its current state.
 

Orkie

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bacteria said:
The GP2x screen is 320x240, I am just trying to tap into this, as the tv out option is awful and not an option in its current state.
Apparently rlyeh has got the TV out working perfectly without odd stretching and will be releasing some code very soon now.
http://www.gp32x.de/board/index.php?showtopic=38013
 
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bacteria

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Fantastic. If I can't get RGB, then S-video tv out will be excellent! (there is a mod on Benheck to make a PSone screen (normally RGB and/or composite) into S-video.

This tv out mod to give 320x240 resolution will be really useful.
 

nubie

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Wow, just wow.

I am on benheck too, I posted a few times in the Portable Screen hacking area.



Edit: Whoops, I feel really stupid. Sorry again. (How's that?)
 

bacteria

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nubie - you started off being helpful, then resorted to being rude, no call for that.

If you read the pdf files you refer to you would realise that the documents are of a very technical nature, hence my comment. I find it hard to read such documents (see below). I am aware about Googling, I don't need you to make detremental comments; if someone already knew the answer it would have saved me a fair bit of time and research. I am intelligent, and probably a lot older than you too.

For your information, not that it is any of your business, I have Aspergers Syndrome (which is a mental condition - intelligent people get this, others get Autistic - Aspergers is linked to Autism), OCD, very mild dyslexia. so I hope you feel suitably stupid and embarrased about your last paragraph; and take a moment in your future postings to consider other people's feelings. BTW - I have a MENSA IQ of 136, in the top 10% of the population; are you still thinking I am not intelligent??
 

nubie

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bacteria said:
nubie - you started off being helpful, then resorted to being rude, no call for that.
Sorry, I am mildly ADHD and am on Dial-up, it makes me kind of pissy.

QUOTE
If you read the pdf files you refer to you would realise that the documents are of a very technical nature, hence my comment. I find it hard to read such documents (see below). I am aware about Googling, I don't need you to make detremental comments; if someone already knew the answer it would have saved me a fair bit of time and research. I am intelligent, and probably a lot older than you too.
Sorry, I will post you the PDF link from the Wiki (Don't feel bad about the Dyslexia, my best friend is Dyslexic, and on the GP2X Wiki the numbers are also Dyslexified, they incorrectly swapped the 8 and 7 :lol: :ph34r: )

QUOTE
For your information, not that it is any of your business, I have Aspergers Syndrome (which is a mental condition - intelligent people get this, others get Autistic - Aspergers is linked to Autism), OCD, very mild dyslexia. so I hope you feel suitably stupid and embarrased about your last paragraph; and take a moment in your future postings to consider other people's feelings. BTW - I have a MENSA IQ of 136, in the top 10% of the population; are you still thinking I am not intelligent??
Sorry again, I can only plead that I am a hopeless ass. I did (sarcastically) apologize, I suppose I will need to delete that and apologize for real here.

In person I am more than willing to help, but I don't know any technical people and live in a small (Pop. 5-7,000) town, so I rarely get to do projects with people, this hurts my inter-personal skills.

I will post the page numbers in the correct PDF shortly.
 
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nubie

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GP2X%20Conexant.JPG

Full picture

Here is a screen shot from the PDF, I am tracking down the proper pins and circuit diagram.

The real trick is in the software, if Rlyeh can fix this I will be modding my GP2X for sure, then I can get you real pics with my Macro camera of how to do the blah blah.



On the subject of a portable N64, are you using an iQue or a real N64?? The iQue is a hand-held (In the controller) N64 for the Chinese Market, it was a real Nintendo product that put the games on flash chips (?? I am unsure, since Lik-Sang got shut down I haven't seen one.)


Edit: here is the site, cached by Google: http://64.233.169.104/search?q=cache:aXUw-...lient=firefox-a

You can see that there is a 9.4MB PDF, I have it on my HDD (I don't know where I got it), but since I am on Dial-up it would be hell to upload it to you guys. You can search the name of it:

DSH-200670-001.pdf

Alternatively I think I will be putting up high-res pictures of relevant sections to RGB output. All of this is useless without Rlyeh's ability to write the registers that can put the Conexant chip into the correct RGB mode.
 

bacteria

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No problem, mate.

Good work BTW.

Yes, I am looking forward to Rlyeh's software to fix the tv out issues; then we just worry about tv out (PSone screen is a good option, and I have a spare screen, well, 2 actually) - this is where the choices come to be 1) tv out via S-video, or 2) RGB.

Looking at the pic of the chip you kindly provided, it doesn't seem obvious which are for the R,G,B, C-sync and ground.

I haven't registered on the site to get the download you mention, not got time for it at the moment, will do at some point. Any time I have free at the moment I am doing my N64/GBA combined portable console mod.

I am using a full-sized (normal) N64 mobo in my BenHeck project. I have read about the ique, but didn't find anywhere to buy one from - anyway, not really relevant as I want to play N64 carts on my system, which an ique can't do.

If you intend to put up the high-res sections of the RGB output (I use ImageShack for my pics), please feel free to up them on this thread.


nubie said:
Wow, just wow.

I am on benheck too, I posted a few times in the Portable Screen hacking area.
Edit: Whoops, I was bullying a sick person, I feel really stupid. Sorry again.



Thanks, pleased you like my BenHeck project.

I'm not "sick", it isn't an illness, it is a condition I was born with. I don't pander to it, I just get on with life. It has positive sides and negative sides too. I also wear spectacles, which is also a condition, it isn't a "sickness" either! "sick", sheesh!! :huh:

Apology accepted though! :lol:
 
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nubie

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bacteria said:
No problem, mate.

Good work BTW.

Yes, I am looking forward to Rlyeh's software to fix the tv out issues; then we just worry about tv out (PSone screen is a good option, and I have a spare screen, well, 2 actually) - this is where the choices come to be 1) tv out via S-video, or 2) RGB.

Looking at the pic of the chip you kindly provided, it doesn't seem obvious which are for the R,G,B, C-sync and ground.
Well, it is and it isn't, they are there in the form of cryptic "DACA ,DACB, DACC, and DACD", which after glancing through the other pins makes them the ones. DAC for Digital-Analog Conversion/Connection.

QUOTE
I haven't registered on the site to get the download you mention, not got time for it at the moment, will do at some point. Any time I have free at the moment I am doing my N64/GBA combined portable console mod.

I am using a full-sized (normal) N64 mobo in my BenHeck project. I have read about the ique, but didn't find anywhere to buy one from - anyway, not really relevant as I want to play N64 carts on my system, which an ique can't do.

If you intend to put up the high-res sections of the RGB output (I use ImageShack for my pics), please feel free to up them on this thread.
I alluded to the fact that you can't access the PDF by mentioning that my link was to Google Cache (a way to see web pages that are locked), mentioning that I didn't remember where I got the file (Showing that it wasn't from the obvious source, the one I linked too), and that I couldn't presently upload the PDF (implying I would need to), and last of all giving the name of the PDF to allow you to perform your own google search (Which you have to do because it isn't available from Conexant).

Anyway, here is a nice diagram showing that pins 59-62 are indeed the correct ones:
GP2X%20Conexant%20HD.jpg


Full Size (To read it you need to click "Download Photo" and view it on your PC)

Assuming that the S-Video pins are correctly done, all we need is two more circuits for SCART/RGB + CVBS, and only 1 more circuit for Sync-on-Green RGB (Some monitors support this) or Y/Pr/Pb (what is on most HDTV/Progressive scan TV sets)

So there you have it, just connect to the extra pin you need and it will be ready to go.

Like I say I can't help much more without some actual hardware testing (I am using an Audiovox D-1500A/EX-50 screen and modding it to support RGB, it only supports S-Video/Composite right now, it seems to be pretty much like the PSOne screen, except the circuit boards are much smaller and made for DVD/Car screens).
 
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Squidge

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bacteria said:
Squidge - great. I can't read it, a bit small. Any idea which points I need to solder to for the 5 wires I need to hook up please for RGB? Thanks!
That chip outputs digital data, RGB is analogue data, therefore you need a digital to analogue converter connected to those DAC lines.
 
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nubie

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Squidge said:
bacteria said:
Squidge - great. I can't read it, a bit small. Any idea which points I need to solder to for the 5 wires I need to hook up please for RGB? Thanks!
That chip outputs digital data, RGB is analogue data, therefore you need a digital to analogue converter connected to those DAC lines.

Squidge, quick question regarding the diagram I posted above:

It appears to say that we have two of the 3 lines for RGB already connected to digital to analog converters for us to get the S-Video. Does this mean that we only need one more DAC circuit to have RGB/YPrPb (SoG RGB)?
 
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clyder14

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cx25874 IC need registers set to output video in the correct mode for SCART.
Was trying to use rlyeh's GP2X minimal library - http://www.retrodev.info to change video output modes.
 
http://www.imageupload.co.uk/files/7j520ycz9b81iww5ales.jpg
 
http://www.imageupload.co.uk/files/qxxvtiqivncku8uxo79z.jpg
 
http://www.imageupload.co.uk/files/6ev1ldbsxd0nb8z8l8vj.jpg
 
http://www.imageupload.co.uk/files/bktmt2p0hdtlgt74w51w.png
 
http://www.imageupload.co.uk/files/ns7gdr98nxgyocw8q7g1.jpg
 
http://www.imageupload.co.uk/files/kpnkc5chcbbnz94v8wgk.jpg
 
The CX25874/875’s PAL Composite Signal should be used by the subsystem to
provide the positive-going Video output/sync output expected by SCART-compliant
display devices. In other words, the Composite Sync output should be fed into the
Video Input (Contact #20-CEI IEC 933-1) on the SCART connector.

Table 1-31. Default SCART Outgoing Signal Assignments
Pin # on CX25874/875 SCART Output
60 = DACA Video[0] = Red Primary Color
61 = DACB Video[1] = Green Primary Color
62 = DACC Video[2] = Blue Primary Color
59 = DACD Video[3] = Composite Video Signal
GENERAL NOTE: Video[0-3] can be routed out of any of the 4 on-chip DACs by adjusting the appropriate OUT_MUXA/B/C/D[1:0] bits
 
Compliance with the European EN50-049 SCART connector standard. Blue
should be received as Pin #7, Green as Pin #11, Red as Pin #15, and CVBS Out
from the CX25874/875 as Composite Out at Pin #19 (Display Side of Connector).

CX25874/875 SCART Outputs for Different SCART Standards
 Red    Green  Blue  Composite/Blanking
 Pin 15 Pin 11 Pin 7 Pin 19 -Composite
Sync Out (To Display)


Part List:

SMD

Resistors
4 x 75ohm, 1%      [0603 package]

Standard

Capacitors
4 x 22pF, 5%        [0603 package]
4 x 270pF, 5%        [0603 package]
4 x 330pF, 5%        [0603 package]

Diodes
4 x Schottky BAT54S / DA204K    [SOT23-N package]

Inductors
4 x 1.8uH, 5%            [IND1210]
 

clyder14

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Two of the RGB colours already output to the extension port.
I lifted two pins on the extentsion port and routed Red and CVBS to pins 11 and 12
 
http://www.imageupload.co.uk/files/1husmrhu2fg6jt7goish.jpg
 
CX PIN  DAC          SCART COLOUR    SVIDEO   EXT PIN    SCART PIN
    
60         DACA =     RED                                       11         
61         DACB =     GREEN                  V_Y          5                   11
62         DACC =     BLUE                     V_C          4                   7
59         DACD =     CVBS                                     12
 
 
but without coding the CX chip to the correct output mode all I got was this -
http://www.imageupload.co.uk/files/ha3j0inc8eaxrt2xs1wy.jpg
 
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