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 Post subject: Game Boy Advance HDMI Adapter
PostPosted: Sun Mar 04, 2018 6:07 pm 


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http://stephens-projects.com/projects/gbahdmi/

Looks like a good solution over the GB player, as far as quality is concerned. Who's excited for this?
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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Sun Mar 04, 2018 6:21 pm 


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I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right? Or by removing the oscillator is the board slightly overclocking the GBA?


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Sun Mar 04, 2018 6:47 pm 



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fact wrote:
http://stephens-projects.com/projects/gbahdmi/

Looks like a good solution over the GB player, as far as quality is concerned. Who's excited for this?

If you want a digital solution for modern displays, sure.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Sun Mar 04, 2018 7:51 pm 



Joined: 24 Jun 2015
Posts: 173
Location: Florida
bobrocks95 wrote:
I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right? Or by removing the oscillator is the board slightly overclocking the GBA?

The GBA is overclocked a little bit, but I don't really notice a difference in the speed when playing a game.

The HDMI output runs at 720p@59.8 Hz due to the use a 74 MHz pixel clock (720p expects 74.25 MHz). The line/pixel counts are spot on and my HDMI analyzer doesn't show any errors in the video timing. I haven't had a single display complain about the refresh rate (5 displays I own, displays at hotels, parents, HDMI distribution boxes in the school lab). One plus of using a 59.8 Hz output is it reduces the amount of overclock required for the GBA.

I'm trying to get an actual 74.25 MHz pixel clock for proper 60Hz refresh. I know the multiplier/divisor values to get something close to 74.25 MHz using a 100 MHz source clock, but the FPGA PLL isn't playing nicely. Ideally I'd have a switch for 60Hz/59.8Hz, that way users can have a choice between minimal overclock or a more compliant refresh rate. Is using a 74 MHz pixel clock even an issue if the pixel count/line count/porch sizes are correct? I would think the display's PLL wouldn't mind a 1% difference and it would still be able to lock on.

I suppose an easy fix is to replace the 100 MHz oscillator on the PCB with a 74.25MHz oscillator, I ordered some from digikey and will see how that goes.


Last edited by Woozle on Mon Mar 05, 2018 2:21 am, edited 1 time in total.

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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Sun Mar 04, 2018 9:26 pm 


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This looks really interesting. I'll keep an eye out to see how this develops.

Just curious for now, though; Is there a way to tell if one's GBA is a 40 pin model from the outside?
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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 12:14 am 



Joined: 24 Jun 2015
Posts: 173
Location: Florida
Pedro Lambrini wrote:
This looks really interesting. I'll keep an eye out to see how this develops.

Just curious for now, though; Is there a way to tell if one's GBA is a 40 pin model from the outside?

Near the battery door you should be able to see the GBA PCB through an opening in the case. There's a code/number on the PCB silkscreen, I think 40 pin GBAs have a zero as the first digit.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 12:40 am 


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Woah, I might be interested in the eventual SP-compatible version of this. I have a spare SP motherboard that I took a screen from to mod into a standard GBA.

The gridlines are a super nice touch too.

bobrocks95 wrote:
I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right?


Maybe not, but I'm wondering if Variable Refresh Rate support in HDMI 2.1 means TV's in the future are going to be more compatible with strange refresh rates.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 2:39 am 



Joined: 24 Jun 2015
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BazookaBen wrote:
Woah, I might be interested in the eventual SP-compatible version of this. I have a spare SP motherboard that I took a screen from to mod into a standard GBA.

The gridlines are a super nice touch too.

bobrocks95 wrote:
I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right?


Maybe not, but I'm wondering if Variable Refresh Rate support in HDMI 2.1 means TV's in the future are going to be more compatible with strange refresh rates.

All that's needed to support the SP and 32 pin GBA is a passive adapter to convert the flex cable pinout.

The refresh rate won't be an issue, I just ordered the proper 74.25 MHz oscillators from digikey so that I can get a 60Hz HDMI output. They're a drop in replacement for the current oscillator, so it should be easy to test and verify that it works.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:09 am 


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Will this kit output vga or 240p like the Vgamite?


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:15 am 



Joined: 24 Jun 2015
Posts: 173
Location: Florida
I do want to make a version with a rgb DAC like the ADV7125 later, but I have a lot on my plate finishing the HDMI kit. If I were to make an RGB output board I would want to regenerate the analog audio as its way too noisy to just pass through from the GBA audio amp.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:19 am 


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Ah you developers, so much to do, so little time.

Still waiting on citrus to finish his GC mod but he keeps getting distracted.

So much is happening in the mod scene right now I love it!


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:20 am 


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Location: Kentucky
Woozle wrote:
bobrocks95 wrote:
I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right? Or by removing the oscillator is the board slightly overclocking the GBA?

The GBA is overclocked a little bit, but I don't really notice a difference in the speed when playing a game.

The HDMI output runs at 720p@59.8 Hz due to the use a 74 MHz pixel clock (720p expects 74.25 MHz). The line/pixel counts are spot on and my HDMI analyzer doesn't show any errors in the video timing. I haven't had a single display complain about the refresh rate (5 displays I own, displays at hotels, parents, HDMI distribution boxes in the school lab). One plus of using a 59.8 Hz output is it reduces the amount of overclock required for the GBA.

I'm trying to get an actual 74.25 MHz pixel clock for proper 60Hz refresh. I know the multiplier/divisor values to get something close to 74.25 MHz using a 100 MHz source clock, but the FPGA PLL isn't playing nicely. Ideally I'd have a switch for 60Hz/59.8Hz, that way users can have a choice between minimal overclock or a more compliant refresh rate. Is using a 74 MHz pixel clock even an issue if the pixel count/line count/porch sizes are correct? I would think the display's PLL wouldn't mind a 1% difference and it would still be able to lock on.

I suppose an easy fix is to replace the 100 MHz oscillator on the PCB with a 74.25MHz oscillator, I ordered some from digikey and will see how that goes.


Sorry Woozle, I didn't realize this was your project. Refresh rate stuff had already been discussed enough in the old thread, my bad.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:26 am 



Joined: 24 Jun 2015
Posts: 173
Location: Florida
bobrocks95 wrote:
Woozle wrote:
bobrocks95 wrote:
I would have to imagine that not all TVs are going to play nicely with a 59.73Hz refresh rate, right? Or by removing the oscillator is the board slightly overclocking the GBA?

The GBA is overclocked a little bit, but I don't really notice a difference in the speed when playing a game.

The HDMI output runs at 720p@59.8 Hz due to the use a 74 MHz pixel clock (720p expects 74.25 MHz). The line/pixel counts are spot on and my HDMI analyzer doesn't show any errors in the video timing. I haven't had a single display complain about the refresh rate (5 displays I own, displays at hotels, parents, HDMI distribution boxes in the school lab). One plus of using a 59.8 Hz output is it reduces the amount of overclock required for the GBA.

I'm trying to get an actual 74.25 MHz pixel clock for proper 60Hz refresh. I know the multiplier/divisor values to get something close to 74.25 MHz using a 100 MHz source clock, but the FPGA PLL isn't playing nicely. Ideally I'd have a switch for 60Hz/59.8Hz, that way users can have a choice between minimal overclock or a more compliant refresh rate. Is using a 74 MHz pixel clock even an issue if the pixel count/line count/porch sizes are correct? I would think the display's PLL wouldn't mind a 1% difference and it would still be able to lock on.

I suppose an easy fix is to replace the 100 MHz oscillator on the PCB with a 74.25MHz oscillator, I ordered some from digikey and will see how that goes.


Sorry Woozle, I didn't realize this was your project. Refresh rate stuff had already been discussed enough in the old thread, my bad.
No need to be sorry, the project has dragged on forever so it's good to refresh memories.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 4:22 am 


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Will there ever be a version that supports RGB output? Is this possible?
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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 6:46 am 



Joined: 11 Dec 2014
Posts: 303
I know there's an existing thread but this looks great. Really does, keep up the good work.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 12:22 pm 


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Joined: 31 Mar 2005
Posts: 174
Location: Scotland
Thanks, Woozle. I'll have to dig out my old GBA stuff and see what I've got. These days, I just tend to use mGBA on my Wii or my GB Micro. :)
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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 3:23 pm 


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Joined: 25 Dec 2013
Posts: 525
Location: Indiana
Syntax wrote:
Ah you developers, so much to do, so little time.

Still waiting on citrus to finish his GC mod but he keeps getting distracted.

So much is happening in the mod scene right now I love it!



I'm actually done with my design :D I've sent a bunch of kits already. Waiting on more QSB's to arrive then will be starting up kits again.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 10:27 pm 



Joined: 24 Jun 2015
Posts: 173
Location: Florida
fact wrote:
Will there ever be a version that supports RGB output? Is this possible?

Definitely possible, just takes time to modify the board to include an RGB chip. Aside from analog noise, making an RGB version would be very straightforward as the FPGA code is greatly simplified. 99% of the hassle of this project is getting HDMI working in Verilog. My first attempt at GBA on a TV used 240p RGB output. https://www.youtube.com/watch?v=Fy_6fZzNGsU&t=29s

But if you want a CRT solution, I would use Extrems GBI for the Gamecube Gameboy Player. That seems pretty ideal for CRT usage.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 10:34 pm 


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Something cool for PC CRT users: something like 1280x960 or 1600x1200 with gridlines. Could something like that be created in the config file? Is the hardware capable?

EDIT: Actually since GBA is 160p, 1120p would be better for a PC CRT instead of 1200p.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 10:55 pm 



Joined: 24 Jun 2015
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BazookaBen wrote:
Something cool for PC CRT users: something like 1280x960 or 1600x1200 with gridlines. Could something like that be created in the config file? Is the hardware capable?

EDIT: Actually since GBA is 160p, 1120p would be better for a PC CRT instead of 1200p.

1280x720 is about the max the FPGA can do. I'm not using an HDMI transmitter IC to keep costs down so resolution will be fixed and limited to 720p.

Did you mean for a VGA output? Could probably try some higher res options in that scenario, but I don't have an analog display that I could test it with. Just some 480i PVMs.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 11:00 pm 


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Yeah I'd be running the HDMI to an HD Fury or something. 960x720 would work too, gridlines would be larger of course. Actually, my CRT already sort of has gridlines when I run that resolution.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Mon Mar 05, 2018 11:45 pm 


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Woozle wrote:
fact wrote:
Will there ever be a version that supports RGB output? Is this possible?

Definitely possible, just takes time to modify the board to include an RGB chip. Aside from analog noise, making an RGB version would be very straightforward as the FPGA code is greatly simplified. 99% of the hassle of this project is getting HDMI working in Verilog. My first attempt at GBA on a TV used 240p RGB output. https://www.youtube.com/watch?v=Fy_6fZzNGsU&t=29s

But if you want a CRT solution, I would use Extrems GBI for the Gamecube Gameboy Player. That seems pretty ideal for CRT usage.

This is really cool, I would presumably be using it through a scaler like the OSSC. Would be interesting to see how it handles line triple, linex4, etc. At that point i wonder if it would be a better option than GBI, as far as visual quality, this would put it close to the scaling you use over hdmi right?
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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 12:27 am 


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I'm disappointed you're still claiming the Game Boy Player is plagued with stutter.

I made GBI because I knew of madVR's smooth motion frame rate conversion. I had that feature working long before audio.
And for those that dislike it, there are video modes with a multiple of 59.7276 Hz.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 1:50 am 


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Extrems wrote:
I'm disappointed you're still claiming the Game Boy Player is plagued with stutter.

I made GBI because I knew of madVR's smooth motion frame rate conversion. I had that feature working long before audio.
And for those that dislike it, there are video modes with a multiple of 59.7276 Hz.


Yeah, GBI in ULL mode in 240p on my PVM is amazing. I've still yet to try it in 480p on my PC CRT's, but I imagine it's just as good.

I'm more interested in this project because I have a spare GBA motherboard laying around. And it might workout better for my PC CRT if it hits higher resolutions.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 2:09 am 


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BazookaBen wrote:
Yeah, GBI in ULL mode in 240p on my PVM is amazing.

I'm guessing you're unaware of the latest developments.

The current ultra-low latency version is gone, it merged with the low latency version and gained all of its features.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 2:08 pm 


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I'll have to give that new version a try, thanks for all your hard work Extrems! most the time I use your Game Boy interface with either the OSSC or FrameMeister. but sometimes I just use a component to VGA transcoder and that looks great on a VGA crt. ( I've been meaning to take pictures of that).

I usually tell Swiss to launch GBI/UL in either 480p or 240p modes, is that the correct procedure, or does GBI have its own resolution selection menu?


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 10:20 pm 



Joined: 30 Mar 2009
Posts: 14
I'm very interested in this project. I'd definitely like a native refresh rate option (or as close to it as possible) as my set is fine with around +/- .5hz from 60hz.

Also, if there's no DAC, a good solution would be to make sure it will output to a Tendak HDMI->RGBHV converter, which are affordable, good quality, are fine with weird refresh rates, and which even pass 240p properly for use with a PVM/BVM.


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Tue Mar 06, 2018 11:32 pm 


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This is awesome news Woozle, I've been hoping for that project of yours to come through soon. Stoked about this

Will the 240p rgb option be a DAC adapter that plugs in the HDMI version, or a completely different version of the kit (it's own thing plugged in the GBA)?


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Wed Mar 07, 2018 12:08 am 


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Extrems wrote:
I'm guessing you're unaware of the latest developments.

The current ultra-low latency version is gone, it merged with the low latency version and gained all of its features.


So if I remember correctly, ULL had less than a frame of lag. Is that the case now for LL?


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 Post subject: Re: Game Boy Advance HDMI Adapter
PostPosted: Wed Mar 07, 2018 12:11 am 


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BazookaBen wrote:
Extrems wrote:
I'm guessing you're unaware of the latest developments.

The current ultra-low latency version is gone, it merged with the low latency version and gained all of its features.


So if I remember correctly, ULL had less than a frame of lag. Is that the case now for LL?


There's some sort of buffer setting now that defaults to 1- I would guess setting that to 0 means it won't buffer any frames?


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