Question Portable snes

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So, i decided to start this other portable building: A portable snes.

I decided to use a SNES Jr. board due to its reduced dimensions.

I got this raspberry pi LCD screen (16:9) for another project (pictures attached). I intend to use a 4:3 version of this screen on the portable snes.

My question is: Wich is the best way to wire it to snes Jr. board without the need to add any other hardware (AV2VGA board, etc)? How to get the best image from this configuration?

PS. Trying to avoid using composite video.

Thanks!
IMG_20210103_104203625.jpg
IMG_20210103_104217592.jpg
 
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Thanks, A_s6! This "3-wire" aproach is exactly what i had in mind. This link just confirmed my theory. But...

The million dollars question is how to put these signal in mentioned LCD screen in order to make it run in RGB mod.

So, i've been searching info about that and i want to share a few things i know untill now.

The LCD board have this strange IC:
IC.jpg


You barely can read what is write on it.

Used a digital microscope and find out that it is a sixthhd hd-1. Googled it quickly searchin for a datasheet and found nothing except for this link bellow where an user calls it "the mystery chip" and claims that it could/should be a realtek RTD2660 similar chip. And to this one, at the same post,there is a datasheet.

Forum where user claims to be a RTD2660

Link directly to complete datasheet:

Have been looking into pdf datasheet and found some information that looks relevant to me. I know how to get RGB signal and c-sync from SNES, what was confirmed by the link sent by A_s6 (thanks again!). I know where to put RGB signals on LCD board, since it have a VGA input.

RGB.jpg


But, where to wire the sync?

So, i decided to search for the word sync on datasheet PDF, and i found at least two interesting information:

First of all:

sync on green.jpg


And second last, the information of wich pin (in theory) should receive sync signal:

sync on green 2.jpg


Is that correct?
Is it really a RTD2660 similar chip?
Is this simple like that?
"Is this the real life?
Is this just fantasy?"
What am i missing?

Could somebody help me to figure this out?
 

A_s6

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the rgb solution doesn’t output vga, so i think you have to do something like this:
 
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The RTD2660 and 2662 *can* support composite sync input, but most firmware used on common driver boards only supports RGBHV (VGA).

If you use a sync splitter (like the LM1881) you can get H-sync and V-sync from the SNES's C-sync output. But the resulting signal will be a progressive 15kHz signal. There's no guarantee that the default firmware of your driver board supports 15kHz VGA.

I would test your LCD with a sync splitter first. If your LCD doesn't work with the sync-split VGA from the SNES, you could potentially modify the firmware to suit your needs. @BocuD might have some more info about that, but it's a definitely a rabbithole.

Alternatively, you could try a ZJ050NA-08C 5" LCD like the one in the BitBuilt store. It's known to work with 15kHz VGA. Another option would be using a different LCD that has S-video input, which on a small LCD might not look too bad. These are the only options I can think of that don't require an external linedoubler board.
 
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the rgb solution doesn’t output vga, so i think you have to do something like this:
Thanks again, A_s6! You gave me valuable info again.
 
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Thanks for your attention, YveltalGriffin!

You've helped a lot! Things are getting clear to me.

If you use a sync splitter (like the LM1181) you can get H-sync and V-sync from the SNES's C-sync output.
I just couldn't find one of these Sync splitters for sale on line. Are they hard to find like that? Is this specification (LM1181) you gave me correct?

Thanks again!
 
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Sorry, it's the LM1881, not 1181. The datasheet I linked is the right one nontheless. There should be breakout boards for sale online, it's a common IC. You'll probably need some exta circuitry to generate H-sync from the LM1881, but there are example circuits online. This page seems like a good place to start. https://www.epanorama.net/documents/vga2rgb/vgamonitor.html
 

Stitches

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I found this old relic sitting in my portable resources folder. Can't for the life of me remember if the 7404 is needed tho

component to VGA.png
 
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I found this old relic sitting in my portable resources folder. Can't for the life of me remember if the 7404 is needed tho

View attachment 15490
And Stitches saves the day, again!

That schemactic will help me a lot! Thanks, man!

About the 7404... Read something about it. It's called a "TTL converter". I have no idea what TTL is but, there is a TTL conection on LCD board i got. I'm kinda in hurry right now, so i will have to wait a little bit till i got enough time to figure It out.


------Double post merged. Do not double post, please use the edit button------


Found this link:


Have no idea if it's related to my questions... As i said... had no time to read It yet.
 
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BocuD

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The RTD2660 and 2662 *can* support composite sync input, but most firmware used on common driver boards only supports RGBHV (VGA).

If you use a sync splitter (like the LM1881) you can get H-sync and V-sync from the SNES's C-sync output. But the resulting signal will be a progressive 15kHz signal. There's no guarantee that the default firmware of your driver board supports 15kHz VGA.

I would test your LCD with a sync splitter first. If your LCD doesn't work with the sync-split VGA from the SNES, you could potentially modify the firmware to suit your needs. @BocuD might have some more info about that, but it's a definitely a rabbithole.

Alternatively, you could try a ZJ050NA-08C 5" LCD like the one in the BitBuilt store. It's known to work with 15kHz VGA. Another option would be using a different LCD that has S-video input, which on a small LCD might not look too bad. These are the only options I can think of that don't require an external linedoubler board.
From my experiments with the 2660 i know that none of the default firmwares it comes with support SOG or 15kHz signals. Unless you want to dive into modifying it to add support, i don't think its worth trying. Modifying the firmware to support 15kHz is definitely possible and i had some decent progress with that already a while ago, but i never got it working properly. I have to say as Yvetal mentioned before, its some really messy stuff; and while i don't recommend it, if you do go down that route, feel free to ask me for help :)
 
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From my experiments with the 2660 i know that none of the default firmwares it comes with support SOG or 15kHz signals. Unless you want to dive into modifying it to add support, i don't think its worth trying. Modifying the firmware to support 15kHz is definitely possible and i had some decent progress with that already a while ago, but i never got it working properly. I have to say as Yvetal mentioned before, its some really messy stuff; and while i don't recommend it, if you do go down that route, feel free to ask me for help :)
Thanks, BocuD!

I'll have to buy another lcd screen anyway, since mine is 16:9 aspect ratio and i want one 4:3 for this project. So, i definitely won't take that firmware modification route. I'm considering get one of these LCD screens Yveltalgriffin talked about.

Thanks to you too, Modler2!

You helped a lot! It's a possibility too. I'm wondering how much i could trim of it.
 
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Well... There are a lot of things think about... By now i'm considering to use composite signal instead of RGB. Could somebody tell me if there is really a big image improvement from composite to RGB in a five inch screen? Does it really worth all this effort?

And, guys... Do you know this board?

Screenshot_20210107-131259.png


Could It be the end of my converter nightmare? It's way cheaper than that one mentioned by Modler2, and, anyway, i wouldn't be able to use the HDMI input since i already ordered the LCD screen YveltalGriffin talked about.

How could i get the Snes signal and turn it in to a VGA signal with this gbs8200? Wich pins should i use? It requires a SNES RGB mod?

Things are kinda getting messy in my head right now.
 
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I am using a GBS8200 with the modified GBScontrol firmware in my αSNES project. The result is virtually pixel-perfect and looks incredible. Lots of guides available on the GBScontrol GitHub wiki on setting it up. Definitely a great option if you're going to use a linedoubler.
View attachment 15535
View attachment 15536
Wow! Very Nice, indeed! That's what i'm talking about! This crispie RGB picture is what i'm looking for!

If you don't mind, let me ask you some questions, YveltalGriffin.

1 - Is the Snes RGB mod necessary in order to achieve this outstanding quality?

2 - Is the Sync stripper still necessary?

3 - From which pins are you getting the signals? Do you have any schemactics of the connections with the gbs8200 that you could post here, if you don't mind?

4 - I saw that you need an Arduino to update gbs8200 firmware... And saw that takes a considerable effort to perform It. Is really worth to update it? Is the difference so brutal like that?

Thanks, again!
 
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Yeah, the picture is really amazing. Indistinguishable from an emulator at times!

1. Yes, this is an RGB-modded Snes Jr., so it's the highest quality RGB signal you can get from a SNES. All models of SNES can output RGB so there's no reason to not use it.

2. No sync stripping or extra circuitry on the SNES is required. Just a few resistors for the RGB mod as described on RetroRGB's site.

3. Check RetroRGB and the GBScontrol wiki for details on wiring stuff up. I'm not sure what revision SNES you have, but it's as simple as connecting R, G, B, csync and GND to the GBS8200 board. You do need to make some modifications to the GBScontrol board like adding a few resistors, but the wiki explains all of that.

4. Yes, you should use GBScontrol instead of the default firmware. The default firmware adds multiple frames of lag and treats 240p inputs as 480i, resulting in image degradation. GBScontrol linedoubling adds only ¼ frame of lag and improves image quality drastically. This video shows the difference:
 
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Yeah, the picture is really amazing. Indistinguishable from an emulator at times!

1. Yes, this is an RGB-modded Snes Jr., so it's the highest quality RGB signal you can get from a SNES. All models of SNES can output RGB so there's no reason to not use it.

2. No sync stripping or extra circuitry on the SNES is required. Just a few resistors for the RGB mod as described on RetroRGB's site.

3. Check RetroRGB and the GBScontrol wiki for details on wiring stuff up. I'm not sure what revision SNES you have, but it's as simple as connecting R, G, B, csync and GND to the GBS8200 board. You do need to make some modifications to the GBScontrol board like adding a few resistors, but the wiki explains all of that.

4. Yes, you should use GBScontrol instead of the default firmware. The default firmware adds multiple frames of lag and treats 240p inputs as 480i, resulting in image degradation. GBScontrol linedoubling adds only ¼ frame of lag and improves image quality drastically. This video shows the difference:

YveltalGriffin, i just can't thank you enough!

That's it! I'll order one gbs8200 right now!

One more question, YveltalGriffin... Have you performed any kind of trim on SNES board or gbs8200?

Thanks again!
 
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I haven't trimmed a SNES (skipped straight to redesigning the 1-chip motherboard) but there are lots of handy SNES PCB scans at both the PCB Strip Club and here on BB. Should be enough to help you puzzle out a trim!

I believe the GBS8200 is a 2-layer board, so it should be easy to trim off some of the empty board on the edges. I can upload scans of that PCB too if you'd like!
 
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