GBS-8220, 23DB Connectors and Leads

[Higgy]

There still are some faint white speckles appearing.
I have a recapped board & am using a decent 2.5A PSU

[amigappc]

Hmmm, no way but to wait then. I migt try with that composite converter....

[Higgy]

It works ok as it is, so you could still buy one.
The work the guys are doing is just going to make it much better.

[dooklink]

Originally Posted by Higgy

@amigappc - I used ebay, bought straight from China. You could aslso try Aliexpress.

I don't think firmware version will matter much because it is going to get bypassed

I took out my RPi from my bartop arcade and am having a go. I have the programme booting but so far I see @dooklink's menu but no AMIGA

Note - there were no header pins where @dooklink connects so I had to remove the solder at the points on the pcb and solder in some header pins.

You need to connect a keyboard and press F2. All of the keyboard shortcuts are listed in the readme on the github page. And those pinheaders can be real anoying if they are prefilled with solder, some are, some aren't.

Hotkeys
Navigation:
F1 - Switch to Pi Menu
F2 - Switch to Currently loaded settings
F5 - Quick save settings
F7 - Quick load settings
Grave/Tilde(`/~)+1 - Switch menu to RGBHV 480p (VGA)
Grave/Tilde(`/~)+2 - Switch menu to YPbPr 480p
Grave/Tilde(`/~)+3 - Switch menu to RGBHV 576p (Non-standard)
Grave/Tilde(`/~)+4 - Switch menu to YPbPr 576p
Fine adjustments:
CTRL+1 - Increase vertical scale (if enabled)
CTRL+2 - Decrease vertical scale (if enabled)
CTRL+3 - Decrease horizontal scale
CTRL+4 - Increase horizontal scale
CTRL+5 - Move image up
CTRL+6 - Move image down
CTRL+7 - Move image left
CTRL+8 - Move image right

[Higgy]

Ah! Sorry I missed the fact I had to press F2. So I press F2 and then the On-Screen RPi menu disappears and I will have the AMIGA's output straight through the GBS- video chip!

I had the keyboard connected and I had a look at the onscreen menu. Quite a lot of adjustment there!
Maybe you could add some text to the On-Screen menu if you update it, for us that don't read the txt 'Press F2 on RPi keyboard to switch output to GBS- ' or something.

So the AMIGA would be a RGBHV 2??p not a YPbPr? I guess.

I look forward to playing again with this then this evening. Many thanks.

NOTE - just to clarify/mention in case this has not been tested as not quite sure how Megadrives etc have been connected.
I am connecting the AMIGA to the GBS- via the RGB header. So I have a SCART cable from the AMIGA going into the GBS-. I wired a female SCART connector onto the plug supplied with the GBS- that goes into the RGB header.

[Higgy]

Ok we have had success!!

There seems to be just one mode compatible so far as the others only accept YPbPr (component) input.
As you can see from the attached screenshot the bottom of the screen is missed off - because it is only expecting NTSC and I am feeding PAL?

@dooklink - do you have an AMIGA? If not the main screen res for a TV would be PAL: 640 x 256 (the RGB mode currently outputs 244p on your settings?)
others are:
1280 x 256 & 320 x 256.
There are also Interlaced modes, the other attached picture is of 640 x 512 and you can see it looks quite strange.

The MAIN benefit I see so far is the 'shimmering' when moving the mouse pointer/or movement is gone!!!! I guess it was cr*ppy GBS- programming . White noise also seemed to have gone! (UPDATE - I am running 'Jesus on E's with no RPi, just GBS- and no white noise...??!? seems a bit random. Turning GBS- on/off seems to affect this)

HOWEVER.... I have seen a strange thing, which hopefully someone might be able to answer. Twice now when have the GBS-/RPi hybrid attached after changing some settings I have not had an output???!!
But then when I rebooted my AMIGA it seemed dead? no HD (CF adaptor) access?
Yesterday it happend and after some time crying I took out the accelerator card & memory and started trying fitting components back one at a time. Thankfully it came back to life
This evening it happened again I took off the trapdoor and let her cool and it has restarted fine and I am running demos etc and it seems ok & I have not had this before??!

Could the GBS- be sending a higher than expected voltage/singal back down the SCART lead?? one for @Stedy to answer maybe.

Looking forward to some more modes @dooklink

[Stedy]

Hi,

Sorry for not replying sooner, I have been busy in the workshop. The first part of my GBS-82XX experiments has now been written up:

http://ianstedman.wordpress.com/gbs-82xx-experiments/

@dooklink

Welcome to EAB,I hope you enjoy your time here.

I have a Raspberry Pi so I might try your scripts soon. Good work in decoding the TVIA-5725 datasheet, it's not an easy read.

If you want to discuss some ideas or want a second opinion on things, please contact me. I've been playing with video systems professionally for 8 years now.

What systems do you connect the GBS-82XX to?

@higgy

Read my blog post and try the revised sync circuit.

Ian

[Higgy]

Nice read Ian (I wish I understood more!).

Currently I have one od your spec SCARTS from AMIGA going into female SCART plug wired into GBS- header. Should I remove all the resistors and have direct connections, apart from resistor on sync?

Not going to have time to work on it anymore tonight so will have to wait till tomorrow.

[dooklink]

Originally Posted by Higgy

Ok we have had success!!

There seems to be just one mode compatible so far as the others only accept YPbPr (component) input.
As you can see from the attached screenshot the bottom of the screen is missed off - because it is only expecting NTSC and I am feeding PAL?

@dooklink - do you have an AMIGA? If not the main screen res for a TV would be PAL: 640 x 256 (the RGB mode currently outputs 244p on your settings?)
others are:
1280 x 256 & 320 x 256.
There are also Interlaced modes, the other attached picture is of 640 x 512 and you can see it looks quite strange.

The MAIN benefit I see so far is the 'shimmering' when moving the mouse pointer/or movement is gone!!!! I guess it was cr*ppy GBS- programming . White noise also seemed to have gone! (UPDATE - I am running 'Jesus on E's with no RPi, just GBS- and no white noise...??!? seems a bit random. Turning GBS- on/off seems to affect this)

HOWEVER.... I have seen a strange thing, which hopefully someone might be able to answer. Twice now when have the GBS-/RPi hybrid attached after changing some settings I have not had an output???!!
But then when I rebooted my AMIGA it seemed dead? no HD (CF adaptor) access?
Yesterday it happend and after some time crying I took out the accelerator card & memory and started trying fitting components back one at a time. Thankfully it came back to life
This evening it happened again I took off the trapdoor and let her cool and it has restarted fine and I am running demos etc and it seems ok & I have not had this before??!

Could the GBS- be sending a higher than expected voltage/singal back down the SCART lead?? one for @Stedy to answer maybe.

Looking forward to some more modes @dooklink

I use the SyncStrike from Arcadeforge.de to connect RGB Scart consoles. I've tested a Megadrive, PAL RGB modded N64 and a modded Wii outputing true low res emulators. The SyncStrike just has LM1881 on it, so I assume you are using something similar. At the moment the RasPi is input through the Y input, so only RGB consoles can be used.

Sorry if the UI is a little hard to understand. You were saying that the Amiga was out of allignment right? There are various settings that you can load from the last option in the UI. Some are for interlaced 15Khz and some progressive. They all line double so 240p -> 480p, 480i -> 480p, 288p -> 576p, 576i -> 576p. These are standard PAL and NTSC timings. Since I don't own an Amiga I'm not sure what it outputs at the momemt. One thing to note is that the horizonal resolution of an analogue video signal only really exists in the digital domain. Once a video signal is analogue, there really isn't a horizonal resolution, only vertical refresh (50/60Hz etc) and the horizonal frequency (15Khz, 31.5Khz etc).

The Megadrive, for example, outputs 240p60Hz or 288p50Hz standard NTSC or PAL timings. But, the actual resolution seen is always 224p. The Megadrive renders it's digital canvas onto 224 lines of the NTSC or PAL lines. So this is why you will always get a slightly non 4:3 image with a pure linedoubled Megadrive. It is meant to be that way and if the Amiga outputs 256p in a 288p frame then the same should be true. If however the Amiga outputs true 256p with non standard timings, then I would need to create new settings for 512p output. This brings new problems since 512p is not standard, and highly unlikley to work with HD LCD TVs.

I use component YPbPr for all PAL signals as 576p RGB is not accepted by LCD Monitors or TVs. One possible work around is to create new settings for 800x600 RGB ouput. Is the Amiga output 50 or 60Hz though?

So I would recomend loading the 288p -> 576p YPbPr settings and plugging it into an HDTV via component. This requires a VGA to 3 RCA cable though. Also, you can adjust the position with the hotkeys listed in the readme and save those settings in the menu.

Originally Posted by Stedy

Hi,

Sorry for not replying sooner, I have been busy in the workshop. The first part of my GBS-82XX experiments has now been written up:

http://ianstedman.wordpress.com/gbs-82xx-experiments/

@dooklink

Welcome to EAB,I hope you enjoy your time here.

I have a Raspberry Pi so I might try your scripts soon. Good work in decoding the TVIA-5725 datasheet, it's not an easy read.

If you want to discuss some ideas or want a second opinion on things, please contact me. I've been playing with video systems professionally for 8 years now.

What systems do you connect the GBS-82XX to?

@higgy

Read my blog post and try the revised sync circuit.

Ian

I'm not sure if you are asking about input devices or output to monitors/TVs. I've listed the consoles I've tried above. I've output my GBS8200s into my Dell PC monitor and a Samsung LCD HDTV. I've also used both RGBHV (read VGA), and YPbPr (read Component). My Dell PC monitor is strange in that it will take RGB and YPbPr with any sync type, be it Sync on Green, Composite or Seperate H&V.

[Higgy]

Hi.
I am not using sync stripper or anything like that. I have the AMIGA directly connected to GBS- via RGBHV connector.
@Stedy will be best to comment, but I think the AMIGA might output the way you describe which is a pain in the ass. The PAL model is also 50Hz.
The AMIGA especially the AGA models (A1200 & A4000) can output all sorts of resolutions. There are even VGA modes. But the problem if I remember correctly from 15+ years ago is that you can set the 'desktop environment' to these nice resolutions, but most games bypass this and will goto the 320x256 resolution. The current GBS- adapts on the fly to the AMIGA signal and reprocess it.

We might be able to find an AMIGA owner nearby to you! It is a great system but to do what it did I think lots of trickery was done

[dooklink]

Originally Posted by Higgy

Hi.
I am not using sync stripper or anything like that. I have the AMIGA directly connected to GBS- via RGBHV connector.
@Stedy will be best to comment, but I think the AMIGA might output the way you describe which is a pain in the ass. The PAL model is also 50Hz.
The AMIGA especially the AGA models (A1200 & A4000) can output all sorts of resolutions. There are even VGA modes. But the problem if I remember correctly from 15+ years ago is that you can set the 'desktop environment' to these nice resolutions, but most games bypass this and will goto the 320x256 resolution. The current GBS- adapts on the fly to the AMIGA signal and reprocess it.

We might be able to find an AMIGA owner nearby to you! It is a great system but to do what it did I think lots of trickery was done

Oh okay. Does that mean your SCART lead has Csync or Composite video as sync?

The resolutions and outputs of old computer systems always seems more complex than old game consoles. I'm sure there will be a solution that works well. I think I will end up having to build a calculator/logic to work out video modes for various input timings. I usally target standard ouput resolutions though, either VESA or CEA.

This brings up another option, and I'm looking for a show of hands as to how important or usefull it would be. Would it be better to scale to 1920x1080p and other common high res timings? The HD Box Pro uses the same chips as the GBS boards and has 1920x1080 and 1920x1200 output resolutions. This would create more scalling artifacts though.

I prefer exact line doubled output with no aspect ratio correction as I use analogue scan line generators (SLG3000 / SLG HD=).

[jbenam]

Originally Posted by Higgy

The MAIN benefit I see so far is the 'shimmering' when moving the mouse pointer/or movement is gone!!!! I guess it was cr*ppy GBS- programming . White noise also seemed to have gone!

That is excellent! That was my major gripe when running my Amiga on an LCD using SCART

Now we just need smooth scrolling and to fix the white speckles issue and it'll be a perfect purchase

[Higgy]

I think yes. As @Stedy's SCART diagram shows TTL CSYNC:

http://eab.abime.net/showthread.php?t=47281

Regarding 1920 x 180 etc, I am correct in thinking this would be more for use with home TV's with VGA input? As I think most of us are using PC VGA monitors (in 4:3 ratio) so they would not be able to display such a high res. My monitors are only capable of something like 1024 or 1280.
Having the option of 1920 is good but having only that option (if I have understood correctly) might be an issue.

Were sorry for you having to check numerous forums but very glad. Your doing a great job.

[amigappc]

1280x1024 - 4:3 most affordable older LCD monitors. CRTs as well. "Must have" because older games were made for 4:3 mostly. Of course 1024x768 is a must too, for 15inch CRTs and LCD monitors.

[Jope]

1280x1024 is actually a 5:4 resolution.. 1280x960 is suitable for 4:3 screens.

Then again, most Amigas don't run in a square pixel resolution anyway.. ;-)

[jbenam]

Originally Posted by Jope

Then again, most Amigas don't run in a square pixel resolution anyway.. ;-)

For that reason I believe the scandoubler (in this case the GBS-82XX) should take care of it, appropriately resizing the screen as much as possible (preferably with integer scaling) and then placing black bars in the rest of the screen.

Do you think that would be doable, dooklink?

Most LCDs actually suck at that and will just squish the pixels trying to adapt them to a fixed resolution which definitely doesn't fit the Amiga

Anyway, if you need another guinea pig I have a Raspberry Pi around and I also intended on getting a GBS-82XX so I'll soon be joining you guys as a beta tester

[dooklink]

Originally Posted by jbenam

For that reason I believe the scandoubler (in this case the GBS-82XX) should take care of it, appropriately resizing the screen as much as possible (preferably with integer scaling) and then placing black bars in the rest of the screen.

Do you think that would be doable, dooklink?

Most LCDs actually suck at that and will just squish the pixels trying to adapt them to a fixed resolution which definitely doesn't fit the Amiga

I agree with that in general, but there are only so many options with the chipset. You can either enable or disable the vertical scalling. Linedoubling is always applied as it processed through the deinterlacer, but without interpolation for 240p etc.

So I'll target standard VESA timings, 800x600, 1024x768, 1280x960 plus 1080p & 720p. Resolutions that are not 4:3 can have black bars at the sides. 800x600 could have black bars at the top and bottom as well if you disabled the vertical scaling for exact 2x vertical scale.

[jbenam]

Originally Posted by dooklink

I agree with that in general, but there are only so many options with the chipset. You can either enable or disable the vertical scalling. Linedoubling is always applied as it processed through the deinterlacer, but without interpolation for 240p etc.

So I'll target standard VESA timings, 800x600, 1024x768, 1280x960 plus 1080p & 720p. Resolutions that are not 4:3 can have black bars at the sides. 800x600 could have black bars at the top and bottom as well if you disabled the vertical scaling for exact 2x vertical scale.

Feared as much... Better than nothing I guess.

800x600 sounds good enough for me as long as I can get exact 2x scaling without any squishing

Great stuff, keep up with the good work! I can't wait to get a GBS-8200!

[amigappc]

Is it better to buy 8220/v3 8200? Ian?

[amigappc]

Also, I wanted to ask what about this, was it ever finished and tested? Can it help in this case? http://www.ianstedman.co.uk/Amiga/designs/RVA/rva.html