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RGB2VGA: customizing a GBS-8200 for a cleaner low-lag image

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2 hours ago, Mr Robot said:

This is great news, I can't wait to try out the VBXE with it! 

 

My GBS is an 8220 and it already has a JST header in place, I can live with it sitting a little high on the board :) 

 

@Stephen when my boards arrive do you want me to send you a kit or make it for you? I know the soldering is half the fun!

Kit would be perfect thanks.  Let me know the cost.

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31 minutes ago, Sugarland said:

Fantastic! Question please.. How hot does it get in your 1050 case with all that in there?

 

Not much actually. Pretty much the same as a 800XL. Things to factor in, DC-DC switching regulators, TTL replaced with hi-speed cmos, DRAM replaced with low power Static RAM, more efficient U1MB replaces original ROMs and MMU. So although the GBS-8200 puts out its own heat, this is offset by the better efficiencies elsewhere.

 

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Getting ready to purchase some prototypes of the GBS carrier board for the XLD. They won't be from OSH Park due to the size of the board, which would result in a prohibitively expensive cost. But I liked the way it looked in purple and gold. However I think I'll opt for black when I get a few made by one of the Chinese manufacturers.

 

Since the GBS-8200 boards when purchased usually come with a wiring harness for P9 and P11, the only other one required will be to attach to P12 going over to the VGA connector board that will mount in one of the unused SIO jack positions on the 1088XLD board. Since only 8 active signals are present on that connector, I have located a source for an 8-pin JST connector with wires on eBay that should work.

 

Top View

RGB2VGA-XLD_top.thumb.png.98f4d6ae69f10464384ac07f7605acd4.png

 

 

Bottom View

RGB2VGA-XLD_bot.thumb.png.c528d76c1dadea857ac5f8a3ffce4deb.png

 

Updated Schematic: RGB2VGA-XLD_schema_10-24-2019.pdf

 

Edited by mytek
Revised Silkscreen -- added information
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I ordered my boards from OSHPark the other day, so am joining the club.  In the meantime I am wiring up the VBXE to the GBS-8200, am finding it difficult to figure out where the Yellow and Gray wires are supposed to go?  VBXE has a RGB control pin, but the two wires left to be hooked up are HSync/VSync.  I've tried to look up connection diagrams, but am not finding what I need.  Any help would be appreciated.

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The only signals required from the VBXE are R, G, B, Csync, and Gnd to P11 (RGBS in) on the GBS board. If you look at the RGB2VGA-XLD board's silkscreen on the board images I posted yesterday you'll see the position of these signals on that connector. Off the top of my head, I believe Csync is the gray wire on the P11 harness.

 

Control would not be used for this application. Nor is separated sync (Vsync, Hsync) required. However, and this is important, a 470-680 ohm resistor should be connected in series on the Csync line from the Atari to the GBS. If you don't do this, the 5V Csync going directly to the GBS will eventually damage a chip on the GBS board. It can't take anything above 3.3V.

 

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29 minutes ago, flashjazzcat said:

Note VBXE does not produce CSYNC. It needs to be picked off the host machine.

Thanks :) .

 

I knew that, but implied otherwise in my last post. However the warning about inserting a 470-680 ohm resister in series with that connection still applies. This limits the current of that line to something well below the rating of the clamping diodes on the GBS Csync input.

 

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And something else that needs to be done to work correctly from a 0.7V RGB input.

 

GBS_pots.thumb.jpg.24f495b56b009e4c0a7c5fb4b6585e8b.jpg

 

 

Revised Silkscreen on PCB to reflect this information...

New RGB2VGA-XLD Boards

 

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30 minutes ago, orpheuswaking said:

Not sure if I asked this or if I missed it. This needs a VBXE or similar correct?

Yes - the referenced GBS board takes a 15.75kHz RGB signal and upscales it to a 31.1 kHz VGA signal.

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Just now, Stephen said:

Yes - the referenced GBS board takes a 15.75kHz RGB signal and upscales it to a 31.1 kHz VGA signal.

Thanks Stephen. I'm contemplating putting a VBXE in one of my machines so that would be a godsend 

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46 minutes ago, orpheuswaking said:

Thanks Stephen. I'm contemplating putting a VBXE in one of my machines so that would be a godsend 

I can't recommend VBXE enough after finally seeing one in action!  It's insanely simple to install in the 1088XLD, if that is your first you should do it to that machine.

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3 hours ago, Evidious said:

The green light blinks on my board blinks.Is that ok? Other than that it looks great!

Blink is good. To be specific: A blinking green LED means you made it through the preset upload process, and you should now be seeing video. A momentary red means presets are being uploaded to the GBS (you'll see this on power-up, and also if you change the dip switch settings).

 

You say it looks great. Does that mean you are displaying VBXE output to VGA? If so can you elaborate, as in tell us what modes of operation, what monitor, and perhaps post a screenshot or two.

 

2 hours ago, Stephen said:

I can't recommend VBXE enough after finally seeing one in action!  It's insanely simple to install in the 1088XLD, if that is your first you should do it to that machine.

And it will be insanely simple to convert it's output to VGA when I release the RGB2VGA-XLD board with it's companion VGA connector board ;) . Well I should qualify that statement, by saying you will need to do some terminal crimping.

 

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15 hours ago, mytek said:

The only signals required from the VBXE are R, G, B, Csync, and Gnd to P11 (RGBS in) on the GBS board. If you look at the RGB2VGA-XLD board's silkscreen on the board images I posted yesterday you'll see the position of these signals on that connector. Off the top of my head, I believe Csync is the gray wire on the P11 harness.

 

Control would not be used for this application. Nor is separated sync (Vsync, Hsync) required. However, and this is important, a 470-680 ohm resistor should be connected in series on the Csync line from the Atari to the GBS. If you don't do this, the 5V Csync going directly to the GBS will eventually damage a chip on the GBS board. It can't take anything above 3.3V.

 

I've installed the VBXE on a 1088XEL using the wiring diagram here: https://atari8bit.net/vbxe-1088xel-wiring-diagram/
 

Is there anything else that I need to wire up?  There aren't specific instructions on how to connect on 1088XEL in the install docs so I was a bit confused until I found the aforementioned diagram.  

Unfortunately the GBS-8200 is saying no signal, after I wired up R-G-B-GND wires.  I momentarily get a green screen, but I'm not sure if that is coming from the VBXE, or the GBS-8200.  I haven't gotten the board from OSHPark yet, but I should still be getting some sort of picture at the resolutions that are available in the stock firmware.  

Do I still need to hook up the CSync w/resistor?  Looking at the 1088XEL Schematic, I'm assuming it is the J27-Buffered/Csync point?  I don't have anything but LCD monitors, so I don't think I will be able to check the RGB output from the VBXE directly, but is there anything else I can look at to ensure functionality?  I could hook up an Oscope, but not really familiar with what I would be looking to verify.  I do get a green led on the VBXE board.  I didn't try the pots yet, I'll give that a shot next, but wasn't sure if I was missing anything obvious.  Even without the Csync hooked up, should I be getting some sort of picture?

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The stock GBS will not necessarily be set to use the RGBS input by default. You would have to get into it's menu and select the correct input, as well as pick an output resolution. And then there are a multitude of other adjustments. Or better yet wait until you have the GBS-PGM board and enjoy the simplicity :) .

 

The GBS will need CSYNC connected via a 470 ohm resistor to J27 on the XEL as well.

 

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both switches up,but it fills the whole screen with A off and B on its a Seiki Monitor/TV , I will try it on a Plain PC Monitor when i get a chance

atari new pix.jpg

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9 hours ago, mytek said:

The stock GBS will not necessarily be set to use the RGBS input by default. You would have to get into it's menu and select the correct input, as well as pick an output resolution. And then there are a multitude of other adjustments. Or better yet wait until you have the GBS-PGM board and enjoy the simplicity :) .

 

The GBS will need CSYNC connected via a 470 ohm resistor to J27 on the XEL as well.

 

I have a VBXE installed in my 800XL. I built an Atari ST 13 DIN to VGA cable and have it running directly from the 13 DIN port on my 800XL to the VGA port on the GBS-8200. I didn't install a resister for the CSYNC line. Would that also be necessary since it is plugged directly in the VGA port and not the P11 harness? Not knowing about the resister, I have had it installed this way for over a year. Never too late if it is better practice.

Edited by Mark loves Stella

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21 hours ago, orpheuswaking said:

Thanks Stephen. I'm contemplating putting a VBXE in one of my machines so that would be a godsend 

I love having the VBXE installed. Not just for the expanded graphics and ability to utilize a modern monitor, but now my 800XL emulates a 48k ZX Spectrum opening up a whole catalog of new software. 

P.S. you also need a Rapidus installed. If you have a Pokey stereo mod installed, you will get the added benefit of an AY sound chip emulated. 

Edited by Mark loves Stella
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2 hours ago, Mark loves Stella said:

I have a VBXE installed in my 800XL. I built an Atari ST 13 DIN to VGA cable and have it running directly from the 13 DIN port on my 800XL to the VGA port on the GBS-8200. I didn't install a resister for the CSYNC line. Would that also be necessary since it is plugged directly in the VGA port and not the P11 harness? Not knowing about the resister, I have had it installed this way for over a year. Never too late if it is better practice.

Although you've been ok thus far, it's safer to run with a resistor. What's probably saved you is that the CSYNC coming out of either the GTIA or the CD4050 is current limited. I think CMOS can only drive about 5 ma at 5V, and I believe NMOS can only source 3 ma.

 

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12 hours ago, Evidious said:

both switches up,but it fills the whole screen with A off and B on its a Seiki Monitor/TV , I will try it on a Plain PC Monitor when i get a chance.

Both switches Up (ON) = 480i 60 Hz (Hi-Rez), 'A' OFF, 'B' ON = 240p 60Hz (standard Atari resolution). Ideally you should be using a square VGA computer monitor. TV's that double as a computer monitor sometimes default to expanding the content to fill the screen, perhaps that's what you are seeing happen. However sometimes they have a way to change their aspect ratio in the setup menu.

 

modes.png.63d3114fb3fbbee1c8a165b73c9e0f1e.png

 

3 hours ago, Mark loves Stella said:

I love having the VBXE installed. Not just for the expanded graphics and ability to utilize a modern monitor, but now my 800XL emulates a 48k ZX Spectrum opening up a whole catalog of new software. 

P.S. you also need a Rapidus installed. If you have a Pokey stereo mod installed, you will get the added benefit of an AY sound chip emulated. 

Now that's a very good application for the Rapidus, as well as the VBXE. And wow what beautiful graphics in that game!!! Now I just might have to save up and buy that combination of hardware :) .

 

Edited by mytek
Corrected dip switch info and added mode table
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22 hours ago, mytek said:

The stock GBS will not necessarily be set to use the RGBS input by default. You would have to get into it's menu and select the correct input, as well as pick an output resolution. And then there are a multitude of other adjustments. Or better yet wait until you have the GBS-PGM board and enjoy the simplicity :) .

 

The GBS will need CSYNC connected via a 470 ohm resistor to J27 on the XEL as well.

 

I did try all the different input modes, turn the pots all the way down, picked an output resolution.  Still no signal detected, though I still haven't connected the CSync, though of course I will be after getting a resistor.  I should be seeing something, even if isn't a great picture, shouldn't I?  I guess I'll try connecting CSync momentarily, just to test if I get a picture.

Edited by wildstar87

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On 10/26/2019 at 10:04 PM, wildstar87 said:

I did try all the different input modes, turn the pots all the way down, picked an output resolution.  Still no signal detected, though I still haven't connected the CSync, though of course I will be after getting a resistor.  I should be seeing something, even if isn't a great picture, shouldn't I?  I guess I'll try connecting CSync momentarily, just to test if I get a picture.

I can pull the CSYNC line and still get a jumbled image, so yes you should see something even without it connected. If you are set to use a RGBS input and are seeing a blank screen something else is going on. As to what? I don't know.

 

5 hours ago, Mr Robot said:

OSHPark finally delivered the GBS test boards! 

Cool 👍 . I'm very curious to see what results you get when running hi-rez modes from a VBXE.

 

-----

On a side note: I have run my GBS board with several VGA monitors as listed below.

  • Sony SDM-HS75P (EXCELLENT)
  • Sony SDM-HS95 (EXCELLENT)
  • DELL 1708FP (OK- a little dim)
  • DELL 1905FP (OK- a little dim)
  • DELL 2007FP (POOR - noisy & dim)

Sony not surprisingly is the best monitor of the bunch.

 

On the SONY monitors these are the settings that I found worked the best...

  • Backlight = 100
  • Contrast = 90
  • Brightness = 60-100 (based on your preference)
  • GAMMA2
  • 9300K
  • Sharpness = 5-10 (based on your preference)
  • Phase = 19
  • Pitch = 1668
  • Hcenter 50Hz = 53, 60Hz = 73
  • Vcenter 50Hz = 50, 60Hz = 0-10

 

Sony SDM-HS95 (19") monitor results @60Hz (NTSC GTIA & ANTIC), GBS 240p mode, Sophia RGB.

Sharpness = 5 for these images, but I actually prefer it at 10 (maximum) for a slightly crisper image.

 

Sony_SDM-HS95_GBS1.thumb.JPG.b0a0ce3285575e3f10ce2c010524ed4f.JPG

 

Sony_SDM-HS95_GBS2.thumb.JPG.a77247d05f5f8563255b8ea5ff8ad433.JPG

 

Sharpness = 10

Sony_SDM-HS95_GBS3.thumb.JPG.89c490f58ab0724e127134dba531c372.JPG

 

Edited by mytek
Corrected 50Hz Hcenter setting, added images

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