So, I'm a new portabilizer, wondering about the psone screen. I'm interested in making the screen modular so it could be used for:
- different portables (discussed here http://forums.benheck.com/viewtopic.php?f=8&t=28205&hilit=modular. Don't necessarily want to use USB)
- as a 2nd monitor for a computer
- just as a generic display with composite
I know the psone screen comes with composite video input fresh out of the box, but I'm wondering what kind of other connections are hackable. So, my questions are:

1) Could I make the screen have a VGA input like what you see on computer lcd monitors today


2) What kind of resolution would the screen have if this is possible? VGA (640x480)? Progressive or Interlaced?

3) What is the relationship between RGB and VGA? I hear people on the forum talking quite a bit about RGB (i.e. SNES outputs RGB), but not much about VGA.

4) Is s-video possible with the USA version of the psone screen?

Thanks much!!

______________
~wajimba

1) No.
2) Not applicable.
3) VGA can go to high resolution, RGB is fixed at something fairly low. VGA uses separate sync, RGB uses composite sync. VGA has a sync frequency of 31KHz, RGB is at 15KHz. You can convert with an upscan or downscan converter.
4) Maybe. It's only been done on PAL screens so far. One necessary chip is missing BUT you might be able to do some conversion a different way.

5) Is there a way to split the csync into hsync and vsync? (I hope I got the terminology right.) Would that cover all the pins that VGA needs? How big would an upscan converter PCB be?
6) Does anyone know what resolution RGB is tied to?
7) Is there a different screen that costs $50 or less that can do both VGA and composite/s-video?

So I did a little more poking around- and it looks like you can combine the h- and v-sync from a VGA signal into a composite sync for use in RGB+S (as in the psone screen, as far as I know)

The site I found it on is http://www.tkk.fi/Misc/Electronics/circuits/vga2rgbs.html

And here is the diagram:


My questions are:
What are the components- specifically the guys called 74LS86 (or 74HCT86 is also usable apparently)?

Are refresh rates going to be an issue, or is that what csync takes care of?

Cost of materials?

Otherwise, if you put that adapter inside the screen case, you could theoretically have a VGA input port on your PSone screen!

No, that circuit only gives you C-sync with 31khz vertical, it does not do any conversion. It won't work.

However some (not all) video cards are able to generate a 15KHz c-sync signal on their own. Google around for the bit-tech.net article on wiring a PSone LCD to your computer.

OK, so this is what I have gathered:
It is possible to make a PSone screen that can connect to an average computer via VGA (at 640x480) if:
You wire up a h and v sync to csync converter and,
You use a program called Power Strip to tune the refresh rate exactly to your screen.

The only issues I see with the theoretical design now are if someone plugs in two video connections at once to the screen. (I want to have both composite and VGA (and a header to the portable)) How would I isolate those two connections? Diodes?
When I get a chance to make this thing I'll put a guide together. I think it won't be for a while though as I'm in the middle of a semester
For now, could someone help me with the parts list for the converter please?
Also, I don't really like the idea of a header to connect the screen to the portable- what are some other options? It has to be pretty small, and durable. Some kind of sliding connection where the pins just make contact instead of a male-female kind of thing? Are there any (relatively) standard connections like this? i.e. I would be able to find them at radioshack or digikey, etc.

For reference, the bit-tech article is http://www.bit-tech.net/modding/2004/07/07/psone_lcd/1

You could use a headphone plug, those are pretty standard for carrying composite video.

I was thinking something with at least 5 pins- rgb + power + ground

Actually the PSone screen CAN accept VGA. Its been around for years now.

http://www.bit-tech.net/modding/2004/07/07/psone_lcd/1

I've been in the modding scene for quite some time now

Actually, that's exactly the article I was looking at.
It says you need to make sure your video card can output csync, and as far as I have heard, most current cards don't. The idea behind the modular screen is you can take it anywhere and use it in a variety of ways; as a tv (via composite), as a computer monitor (via VGA), or in a portable, via RGB (or composite)- not sure what kind of connection to use here- I guess I would actually need 6 pins. Ideas anyone?

So, to use the screen as a monitor, I want to be able to connect it to any average computer, hence the h+v sync to csync converter. Again, I would like some help with the circuit to do this. Does it look like the diagram I posted earlier in this thread will do the job effectively? What parts would I need to build the circuit- or, is it a pretty complex piece that would be better if I could find it premade somewhere. Anyone know where to get it? (cheaply)

Sorry for such long posts- if you have good info/ideas for one of my conveniently color coded questions, please post and don't feel like you have to answer all of them at once.

EDIT:
Found a parts list for the h+v2csync converter on the original site:

C1 22 uF 10V electrolytic
C2 22 uF 10V electrolytic
R1 2.2 kohm
R2 2.2 kohm
R3 1.8 kohm
R4 1.8 kohm
R5 2.7 kohm
R6..R8 47 ohm
U1 74LS86 or 74HCT86
T1&T2 BC 547

What is up with these last 2 guys? When I look up 74LS86 on digikey, it comes up with about 20 options. What kind of current should it be rated for?
Is there something special about the BC547 or can I just use any npn transistor I pull out of some old electronics? Again, what kind of amp/voltage rating should it have?

Interesting... you are bringing up a similar idea with your first posts as I did when I was just getting started. The thread you linked to at the beginning, in fact.


I had the same durability beef with headers, which is why I settled on USB (although I haven't done anything with the concept yet). The most obvious alternative is to use the connection the video cable makes with the system - it's made to be inserted and removed repeatedly. The only reason I didn't want to use them is that USB is smaller.

Yeah, I'm bringing up the same idea because I didn't really like the USB idea. Disastrous results could ensue from plugging it in to an actual usb port.
What kind of options are there for headers? I'm thinking something along the lines of:

But a little more beefy. It might work if you put the other end on the screen, and made the slot have very little wiggle room, and/or kind of funneled it down so that it fit perfectly without catching the pins the wrong way. Even still I don't think it would be durable enough. I just had to bend the pins of a VGA connector back into place today- and those are even better protected.

Yeah, but who's going to do that? You know better.


What about using the AV ports that they use on the pocket TVs? It looks like an audio plug, but it's composite video and L and R audio as well. You could use two if you needed more connections.

If you do want to use headers, do it this way: rather than having them mounted on each piece (so they'd need to hit perfectly during insertion), have a little bit of cable that you plug in first before sliding the screen into place. That way, you don't risk accidentally bending pins.

Ah, 2 AV ports. That's a total of 8 connections, which would meet my need for 6. That means I could go on the cheap and just get some regular stereo mini jacks. 6 connections total. Put the female ends on the screen so nothing's jutting out. Me likes.
Thinking back over my number 6, would I need more than one ground connection? Will signal degrade if I'm grounding red, green, blue and power to the same pin?

My only real concern is size. How big a footprint will 2 headphone jacks take up inside? 1" square?

I don't think it needs to be high current, look for something with fast switching speed. I think you can substitute a 2N4401 for a BC547, but don't quote me on that.