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

[+mytek]

13 hours ago, Mr Robot said:

My csync isn't connected via a resistor, am I slowly creating a hole in the universe or something else I'm unaware of?

Everything on the GBS is using 3.3V as its power supply. So if you give it a 5V sync, yes eventually you will damage the sync input if no current limiting resistor is in series. The XEL's sync output is lower then 5V, so it might not be as destructive, but I would still advise using a 470 ohm resistor in series just to be safe.

 

Edit: the sync voltage input of the GBS is really meant to use a 1V signal, which would have been typical of RGB monitors BITD. SCART is even lower, requiring 0.7V.

 

[chevymad]

Is Csync not on the 13pin monitor port? I built a 13 pin to vga connector and have been using that, and the vga in port on the gbs since it's an external mount at this point. If it is on the monitor port, is there a conveniant place to put the 470 ohm resistor? or should I add it to my monitor to vga adapter?  I tried running from j27 - 470ohm resistor - gbs gray wire tonight and it's no different then what I was doing .  Screen is moved to the upper left corner in all modes, all modes say "out of sync" on my monitor, all 3 gbs-pgm devices act the same. 

[+mytek]

11 minutes ago, chevymad said:

Is Csync not on the 13pin monitor port?

Yes it is, but it also exists as a single pin test point (J27) near the RGB-THRU connector. If your GBS were internal that would be the one to use, but it looks like you are running this external so sourcing it from the DIN-13 makes good sense.

 

11 minutes ago, chevymad said:

I built a 13 pin to vga connector and have been using that, and the vga in port on the gbs since it's an external mount at this point. If it is on the monitor port, is there a conveniant place to put the 470 ohm resistor? or should I add it to my monitor to vga adapter?

Yes adding the resistor to your monitor to VGA adapter seems like a good way to do it.

 

11 minutes ago, chevymad said:

  I tried running from j27 - 470ohm resistor - gbs gray wire tonight and it's no different then what I was doing .  Screen is moved to the upper left corner in all modes, all modes say "out of sync" on my monitor, all 3 gbs-pgm devices act the same. 

So I think in order for anyone to help you with this we need to know more about what you are doing.

 

I think you mentioned that you are using the GBS-PGM board. If so did you jumper P8 on the GBS RGB to VGA video board as well? Just want to make sure about that, since not doing so would mean the GBS-PGM is not even getting used, and the GBS VGA board would default to its own settings instead.

 

Not using CSYNC should just give you a scrambled picture, but if I understand correctly from your previous posts that wasn't the case.

 

What video mode are you using on your VBXE?

 

Keep in mind that the output is non-standard due to the Atari timing, so it wouldn't be unusual to have to adjust things like pitch, position, and size on the VGA monitor.

 

Also keep in mind that the higher rez modes of the GBS-PGM are test versions, and I haven't personally seen them in action, so there may be problems with using them. I presently have only tested with a Sophia RGB board in both PAL and NTSC in the lower resolution modes, and it works very good.

 

[chevymad]

So csync is in fact hooked up then, but without resistor at the moment. p8 is jumpered. VBXE is in ntsc. With the gbs-pgm installed the monitor says "out of sync" yet shows a picture that fills 3/4 of the screen and is in the upper left corner, different gbs-pgm modes change size and shape of picture. The "out of sync" message is from the monitor menu, because of it, I can't get to any of the video settings on the monitor. Pushing menu gets rid of the message or brings back the message. The 50hz modes will show garbage if computer is cold booted, but will show good video if switched while on. 60hz modes work fine from cold boot. I'm thinking there's some incompatibility with my monitor, an NEC accusync lcd. Frankly, i'm pretty happy with the stock gbs video, so I may just add the resistor and leave it be. 

[+mytek]

Thanks for the info .  I'll  have to revisit the GBS-PGM firmware and see if I can get it to play nicer with the monitor so that doing an automatic self adjustment yields a proper image, without the manual tweaking. For the most part I am just using some generic preset tables that I've tweaked in a few places. Probably just needs to be better adapted to our A8's. I do consider the firmware to be open source, and the tools to work with it are freely available, so perhaps someone will beat me to it. After all the source is included as part of the zipped firmware download available on my website.

 

[chevymad]

Does anyone have a spare main board for sale? I allready have a few of the vga connector board coming. I may end up just cutting a piece of hobby board to use for an internal mount for my gbs since stock seems to work with my monitor. 

[chevymad]

Mytek, question on the buy link for the 8pin wire harness on ebay. I ordered from that link, and it appears the pins aren't spaced correctly. Pins are much too close together. Unless I've read incorrectly, I think this is supposed to connect the GBS to the remote VGA connector right? The other buy link is for the end connectors, are you just using the wires and attaching the correct ends? 

[Dropcheck]

On 4/18/2020 at 4:47 PM, chevymad said:

Does anyone have a spare main board for sale? I allready have a few of the vga connector board coming. I may end up just cutting a piece of hobby board to use for an internal mount for my gbs since stock seems to work with my monitor. 

I have 4 extra coming in next week.  They are red to match my main board. ? If that works we can go to IM to work out details. 

[+mytek]

2 hours ago, chevymad said:

Mytek, question on the buy link for the 8pin wire harness on ebay. I ordered from that link, and it appears the pins aren't spaced correctly. Pins are much too close together. Unless I've read incorrectly, I think this is supposed to connect the GBS to the remote VGA connector right? The other buy link is for the end connectors, are you just using the wires and attaching the correct ends? 

Hmmm... that's odd if it's too small. I'm pretty sure that's the one I used on the GBS side. The Dupont connector would need to be installed on the other side to plug into the VGA connector board.

 

 

Although I remember at the time ordering from two different sources and one of them wasn't correct. Hopefully I didn't get them mixed up.

 

This was the other one I had ordered: JST-XH 8-Pin 2.5mm Female Connector Adapter with Wire & Male connector x 10 SETS

 

I'll check the pin spacing tomorrow and let you know what I find out.

 

 

[chevymad]

The one the link took me to has 2.0mm pin spacing. 

 

Edit: Ah yes, the connector fits on the GBS side. Thanks for the clarification.

Edited May 7, 2020 by chevymad

[+mytek]

8 hours ago, chevymad said:

The one the link took me to has 2.0mm pin spacing. 

 

Edit: Ah yes, the connector fits on the GBS side. Thanks for the clarification.

So we're good? The link on my website is the right one?

 

[chevymad]

Yup, we're good. Hey, I had a 50/50 shot of picking the right end right? lol.. some days.  I actually looked at the wrong connector on the GBS board too.. Sorry to bother you with my mistake again.

[+mytek]

3 hours ago, chevymad said:

Yup, we're good. Hey, I had a 50/50 shot of picking the right end right? lol.. some days.  I actually looked at the wrong connector on the GBS board too.. Sorry to bother you with my mistake again.

No problem, but I do try to post useful pictures to help guide people to the right conclusion .

 

Glad to hear that all was ok ? .

 

[Rybags]

ed - this is in response by accident to stuff around page 2, I didn't realise I'd not read this thread in so long (opened to first unread)

 

The default cores don't do anything other than 240p type video and haven't the VGA ones been deprecated?

 

480i type interlace is a hardware bug exploit by software to Antic and VBXE or not isn't important.  VBXE itself in enhanced legacy mode has nothing to do with Sync generation.

I do believe though that it does PAL/NTSC detection by counting how many scanlines between VSyncs (?)

Or possibly it just doesn't need to know.  Palette is system agnostic, and we generally know that Antic is generating playfield video once the long period of HBlank command finishes.

Edited May 8, 2020 by Rybags

[+mytek]

7 hours ago, Rybags said:

ed - this is in response by accident to stuff around page 2, I didn't realise I'd not read this thread in so long (opened to first unread)

 

The default cores don't do anything other than 240p type video and haven't the VGA ones been deprecated?

 

480i type interlace is a hardware bug exploit by software to Antic and VBXE or not isn't important.  VBXE itself in enhanced legacy mode has nothing to do with Sync generation.

I do believe though that it does PAL/NTSC detection by counting how many scanlines between VSyncs (?)

Or possibly it just doesn't need to know.  Palette is system agnostic, and we generally know that Antic is generating playfield video once the long period of HBlank command finishes.

Thank you for the explanation even though it comes at a later time.

 

So if I'm reading this right, the 480i and 576i presets that were added to the 4 possible selections in the RGB2VGA-XLD are not of much use. Of course those selections could be utilized for other variations of the 240P and 288P that might better suit a particular monitor, since the presets control quite a few other parameters of the GBS.

 

Even the existing presets for the two supported standards could likely use some adjustment to better suit the video timing of the Atari, since I find that using AUTO setup in a VGA monitor doesn't result with a centered image, thus requiring manual adjustment of the monitor instead. The very well documented source code is provided so that hopefully others with more patience and diligence than I, might eventually tweak the firmware's built-in preset tables for a more perfect end result. The GBS's video scalar chip which is what the RGB2VGA-XLD talks to, is a very complicated beast to configure. Of course if the end user so desires the PIC16F1572 chip and the P8 jumper can be left out, thereby letting the GBS utilize it's own method of adjustment, although you'll have to put up with the annoying Chinese writing splash screen every time the system is powered up, and have to wait for it to disappear before video is passed through.

 

BTW, I would appreciate any submissions of improved firmware, and gladly make that as a JOY2PIC compatible download on my website.

 

[Rybags]

I was referring to VBXE firmware in this case, not the GBS (I have one but haven't done anything in the way of modding or customizing)

[+mytek]

46 minutes ago, Rybags said:

I was referring to VBXE firmware in this case, not the GBS (I have one but haven't done anything in the way of modding or customizing)

I was as well, since the firmware I employ in the RGB2VGA-XLD board's PIC processor had extra modes added at the suggestion of other A8 VBXE users to hopefully support the 480i and 576i video as I was told is possible from the VBXE. Not having experience with the VBXE myself, I didn't realize the full story behind what the VBXE could and could not do.

 

I suppose all is possible on either end, if the right firmware for such were developed.

 

Edit: Although I was told about the desire to have 480i, no mention was made of 576i which was an assumption on my part that this should have also been possible. All presets are derived from ongoing works in the public domain being done by various people for trying to make the GBS better for the retro scene. Full Story on the RGB2VGA Project.

 

BTW here some samples of the actual unretouched image from my Sony RGB monitor converting from Sophia RGB over to VGA via the GBS-8200 using the new presets.

 

[chevymad]

On 10/25/2019 at 6:50 AM, flashjazzcat said:

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

Spent most of the night trying to figure out why I had no signal when using the P11 input, but had good signal when going from my monitor port to the VGA connector. Finally saw this and figured out CS and C were not the same thing. Thanks!

[rockdoc2010]

Well,

It took me a three week endeavor to get this to run but it now works.

1088XLD and VBXE and VGA2RGB carrier board.

THANK YOU MYTEK!

 

I have very muted colors. Attract mode colors are off. 

I flashed my GBSCTRL PIC out of unit using the joy2pic stick.

Switches in the correct place and I have a stable pic to my VGA input on my screen.

I have a DELL monitor on the way and perhaps that will help.

 

We will see...

Douglas

 

[+DrVenkman]

6 hours ago, rockdoc2010 said:

I have very muted colors. Attract mode colors are off. 

Make sure to adjust the RGB potentiometers on the GBS8200 to maximize color gain (full counter-clockwise, if I recall correctly). The stock GBS8220 firmware menus also let you configure saturation, if I recall correctly. I don’t have one of Michael’s modified firmware boards for mine so I don’t know if he’s retained that feature or not.  Your monitor itself will have at least brightness and contrast controls. Higher-end monitors may also have independent saturation, color temperature and possibly even independent RGB adjustment also. 

 

And finally, the VBXE itself has a PAL color palette by default. There’s a whole thread about this around here if you search. I thought we had Candle convinced to provide those of us in NTSC-land with a good NTSC palette to write to the firmware so our games and applications will look like we expect, but that seems to have never happened. I know he’s likely to be busy with other new hardware and just hasn’t gotten around to it. You can load a batch file or something in SpartaDOS X to change the palette if you want, but it will only persist until the Atari is power-cycled.

[+mytek]

2 hours ago, DrVenkman said:

Make sure to adjust the RGB potentiometers on the GBS8200 to maximize color gain (full counter-clockwise, if I recall correctly).

Yes that is correct, since the GBS board's stock settings are based on supplying 1V peak-to-peak RGB and not the 0.7V that is the norm for the VBXE or Sophia.

 

2 hours ago, DrVenkman said:

The stock GBS8220 firmware menus also let you configure saturation, if I recall correctly. I don’t have one of Michael’s modified firmware boards for mine so I don’t know if he’s retained that feature or not.

When header P8 on the GBS board is shorted (jumper installed) the original firmware has left the room and the PIC MCU's code has taken over, thus all the original control features provided by the original GBS firmware are rendered inoperative. The main idea is to be able to use the dip switch on the carrier board to accommodate different configurations. However keep in mind that the RGB2VGA-XLD carrier board can be used without the PIC chip and thereby revert to the original GBS firmware by not jumpering P8. This can also be done with the PIC chip still installed. So if you like what the original GBS board is doing, by all means use its stock firmware. The carrier board is really more about providing an easy method to supply filtered power to the GBS from the XLD, provide a solid mounting system, provide independent buffering of the RGB, and offer a convenient way when coupled with the VGA2GBS board to have a more professional looking back panel VGA connector.

 

Theory behind the PIC MCU inclusion

The PIC's GBS preset tables contained within its firmware which are written in GCB, can be tweaked to match the desired resolution of the source device, specifically with the Atari in mind. The PIC firmware provided on my website as well as the links to documentation and to the Shmups Forum was meant to serve as a starting point, with the PIC firmware considered as BETA. Using Great Cow Basic which is freely available, and writing well documented code, was intended to allow others to more easily expand upon what the BETA firmware can do. And as with much of the development hardware and software I offer on my AtariBits website, this stuff can and will be a work in progress - some more than others. In the future I would be very happy to offer alternative GBS code written by others as additional downloads from my website.

 

 

8 hours ago, rockdoc2010 said:

It took me a three week endeavor to get this to run but it now works.

1088XLD and VBXE and VGA2RGB carrier board.

Congrats on sticking with it and getting it to work ? .

 

[rockdoc2010]

Unfortunately,

 

I am using the PIC as is but I have to go thru the button sequence to select my resolution every time I power back up. and I found that you have to be quick about it.

I am also still getting the red led blink followed by two short blinks.

When I adjusted the onboard switches to a different resolution, i did get a half second green led. I assume from what I have read in the thread that that is the GBS initializing the parameters.

 

Cant wait for Sophia 3 to come out.

 

[+mytek]

2 hours ago, rockdoc2010 said:

I am using the PIC as is but I have to go thru the button sequence to select my resolution every time I power back up. and I found that you have to be quick about it.

That's interesting, but it really shouldn't work like that since the P8 jumper is suppose to completely shutdown the internal firmware and then open up reception on the I2C input coming from the PIC chip. The PIC chip has no code to look for input from the buttons, and will only respond to the dip switches.

 

2 hours ago, rockdoc2010 said:

I am also still getting the red led blink followed by two short blinks.

That's the version number indication of the PIC firmware. Long blink = 1 and two short blinks = 1.2 for the full version number. By your description it looks like the LED might be backwards, since that should be in GREEN not RED.

 

2 hours ago, rockdoc2010 said:

When I adjusted the onboard switches to a different resolution, i did get a half second green led. I assume from what I have read in the thread that that is the GBS initializing the parameters.

Yes that is correct.

 

2 hours ago, rockdoc2010 said:

Cant wait for Sophia 3 to come out.

I think you meant to say Sophia 2. And yes that'll be the ultimate solution.

 

Leave out the P8 jumper and remove the PIC chip to adjust things using the buttons and menus via the original GBS firmware and see if you like that better. The PIC code is very experimental and won't always play well with your monitor (I use Sony VGA monitors which work very well for me).

 

 

[Mr Robot]

One unexpected side effect of the firmware override is it becomes incompatible with my video capture device. The GBS8220 outputs at max 1024x768 and I can capture that but with the GBS board it outputs 1280x1024, which I cannot capture.

 

[+mytek]

2 hours ago, Mr Robot said:

One unexpected side effect of the firmware override is it becomes incompatible with my video capture device. The GBS8220 outputs at max 1024x768 and I can capture that but with the GBS board it outputs 1280x1024, which I cannot capture.

Yes an unfortunate side effect. However there probably are presets out there in the universe that would give you a 1024x768 display, although it would require some experimentation. And now that I think about it, the dip switch legend should have been left off the board silkscreen to better accommodate user versions of the PIC firmware with custom resolutions.

 

If it wasn't for the long delay and chinese splash screen each time the GBS starts up I probably wouldn't have even bothered with the PIC chip aspect, and just made it strictly a buffered carrier board, utilizing the GBS's original firmware.