Introducing the VeriSNES (FPGA-based SNES)

Discussion of hardware and software development for Super NES and Super Famicom. See the SNESdev wiki for more information.

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greatkreator
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by greatkreator »

Likely the price won't be cheaper than a PC capable to run any SNES emulator (a PC which can do a lot of other jobs as well).
Power consumption? Maybe I am not enough environment friendly or just my electricity price 0.10 USD per kWh is not high enough to take it in account...
I really can't understand what's the point of this product comparing to the already existing disgusting ARM solutions?
It doesn't offer a full hardware clone. It won't help anyhow to create new full copies of beloved SNES.
It will be the same approximation of SNES' hardware work as SNES emulators already do for years.
Probably a bit more precise but the original SNES console will be the original SNES console.
And it's really sad. Because I really would like to make SNES to live forever.
I would like to have a full 100% hardware copy of SNES hardware.
Why not to make crowd funding for that? Why to produce another something that resembles SNES but isn't it.
Is to create 100% full hardware copy still impossible in 21 century? Or will it cost millions dollars?
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TmEE
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by TmEE »

Interest exists, skill maybe too, money probably can be dug up for it but it seems there's no time.

I'm all over hardware, partly for reasons Tepples has mentioned. Reimplementation that gets results that are for all intents and purposes same as original hardware is good enough for me (and many others) and when you can adjust some things to likings of oneself things get even better (i.e I absolutely don't want the blurry RGB of original hardware and I would like multiple additional options in the sound path such as zero crossings detection for volume changes and few other things). Realtime software emulator would be fine but those aren't practical for the most part, so hardware is only good way to go about it.
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greatkreator
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by greatkreator »

As a open-source project it's absolutely ok.
But to get enough(or even more) money as a crowd-founding project for that it should be much more interesting.
A too niche interest can't attract enough founders.
And it seems like you are trying to come up with reasons for the project existence than the project offers anything itself.
And it correlates well with the words that the project was intended to practice FPGA skills and just for fun.
Why not to make something like Analogue NT? Why to give false expectations and make me sad?
I really would like to have a brand new SNES with high quality video output.
I really would like to donate up to 1000 USD for such a project just to see it to be done.
I really don't want to donate even single dollar to get another chinese clone alike fake. There a lot of that ARM-based c...p for 20 dollars.
Harrumph
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by Harrumph »

greatkreator wrote: I really can't understand what's the point of this product comparing to the already existing disgusting ARM solutions?
[...]
I would like to have a full 100% hardware copy of SNES hardware.
FPGA hardware simulation is nothing like an ARM based emulation clone.
As far as I've understood, in the finished implementation, this will be as close to a 100% hardware copy as one could hope to get, just like the Analogue NT Mini is for NES.
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greatkreator
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by greatkreator »

If it would be so then it would really cool.
But the question is how to do that without reverse engineering?
It will be 99.98% solution but not the same. Those 0.02% will always show who is who.
As far I understand he uses the same "symptomatic" approach as emulators (not a reverse engineering approach) but just with better "tuning".
Let's see what the author will say. Without him I just guess.
tepples
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by tepples »

greatkreator wrote:I really can't understand what's the point of this product comparing to the already existing disgusting ARM solutions?
You need essentially zero latency to make the Super Scope or Justifier light gun work as advertised. I don't see how to do anything like that with a Raspberry Pi.
greatkreator wrote:It doesn't offer a full hardware clone. It won't help anyhow to create new full copies of beloved SNES.
I guess people disagree on what's a "full hardware clone". This is an approximation, but it's close enough that you can build a board around it, put a cartridge in, and it'll work with everything commercial and homebrew other than contrived test ROMs, even if it uses an unanticipated coprocessor.
greatkreator wrote:Is to create 100% full hardware copy still impossible in 21 century? Or will it cost millions dollars?
You mean something that copies the Super NES at as low a level as Visual 2A03 copies the NES? It would probably cost a few thousand dollars to decap, delayer, and micrograph a 1/1/1, 2/1/3, and 1CHIP chipset, and then trace polygons from the photographs.
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greatkreator
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by greatkreator »

I see.
It does make sense to some extent.

Yes that exactly what I dream about.
I would support such a project with a pleasure as much as I can.
Exactly 101% SNES (not something that looks like very much as SNES) will live forever.
But unfortunately I don't know whether other people would support my dream.
Maybe the majority of people are not demanding perfectionists as me and they will be ok with such a hybrid half-solution.
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mikejmoffitt
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by mikejmoffitt »

tepples wrote:You need essentially zero latency to make the Super Scope or Justifier light gun work as advertised. I don't see how to do anything like that with a Raspberry Pi.
Would an exact line doubler or tripler, adding exactly one line of latency (1 / framerate * n. lines seconds) allow the super scope, justifier, or even original zapper to work correctly? In the case of a 480p line-doubled VGA output, or even 720p line-tripled output, this would be a possible path to lightgun compatibility on a slightly more modern display.

Also, what would be a good < 1 frame solution for dealing with interlaced hi-res mode? Would it be better to

a) Allow a slight wobble on the screen as the line-doubled frames are output without weaving in a buffer, at the moderate expense of vertical clarity, or
b) Switch to a 1-frame-lag buffer solution, just for interlaced mode, at the expense of needing extra memory for a framebuffer?

Alongside, maybe:

c) Force ignore the interlaced mode flag, having the output be a progressive double-strike image?

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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by tepples »

Assuming a CRT capable of 480p CRT at twice-NTSC line rate, as opposed to 720p, 1080i, or an LCD:

Super Scope and Justifier can measure X in addition to Y. This requires the signal to be 15.7 kHz, not 31 kHz, as 31 kHz means only half of the electron beam time can be accounted for. Games could perhaps be patched to work with this, or the console might be able to do funny things with the HV latch to make it count twice as fast when outputting 480p.

Zapper should work with a doubler, as previous tests during the development of Zap Ruder have shown that it's only precise enough to detect Y, not X. But you'll need to use a CRT, use 480p, and crank up the darkening of every other scanline to 100% so that the light sensor circuit sees half the actual line frequency.

An LCD won't work. The light sensor circuit (photodiode + demodulator) can't even see light that doesn't flicker at close to 15.7 kHz. And even if an LED backlight were to flicker that fast, it probably wouldn't flicker individual lines from top to bottom the way light gun systems expect.

Nor will upscaling to a 720p CRT work very well, as 720p uses 4% vblank time (720+30 = 750 lines per field), compared to 240p's 8.4% vblank time (240+22 = 262 lines per field). This means line tripling at 720p will produce 750*60/3 = 15.0 kHz, not 15.7 kHz. This difference is why the Hi-Def NES needs to store pixels in a circular buffer. If you tried to use a Zapper with a 15.0 kHz line rate, it'd probably work with really simple games like Duck Hunt, but more complex games that measure Y position (Operation Wolf, Top Hunter, Zap Ruder) will mistrack vertically by up to 5 percent.

Interlace can be done trivially with a 100% scanlines upscaler. There's "a slight wobble" when you play it on an SDTV anyway, and it probably won't be any more apparent when you upscale.
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mikejmoffitt
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by mikejmoffitt »

Thank you for clarifying lightgun compatibility.
tepples wrote:Interlace can be done trivially with a 100% scanlines upscaler. There's "a slight wobble" when you play it on an SDTV anyway, and it probably won't be any more apparent when you upscale.
While this is an easy solution, using visible scanlines (i.e. darkening one or more scanned out duplicate lines) results in a significantly darker image than the normal line-doubled one. This does solve the problem trivially, but I don't think a dark and flickering solution is the best default one. This would solve the case nicely for people who want to use a scanline filter, however.

So, alongside that option for a scanline mode, a solution might be either

a) Allow a slight wobble on the screen as the line-doubled frames are output without weaving in a buffer, at the moderate expense of vertical clarity, or
b) Switch to a 1-frame-lag buffer solution, just for interlaced mode, at the expense of needing extra memory for a framebuffer.

Maybe both would be best, at the user's choice.
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by tepples »

Fortunately, I made a test card of the three solutions eight years ago.

Image
Interlacing test card (GIF at 1/3 speed to exaggerate visibility of slight wobble)


Left: Weave (1-field lag); center: fields with visible scanlines; right: line-doubled fields
Top row: Unfiltered image; bottom row: image blurred vertically before interlaced display
Left and right are darkened 30% to compensate for center's loss of brightness
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mikejmoffitt
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by mikejmoffitt »

The right-side solution is how it would look without the scanlines, then. I think as a zero-lag solution, it is adequate, although it must be acknowledged that it is not visually ideal. Fortunately, very few games utilize the interlaced mode during gameplay.
Kismet
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by Kismet »

calima wrote:Eh, ARM boards capable of SNES emulation are about 20$, FPGA boards able to run this would be on the order of 100$ (my guess).
Likely more, if jwdonal wants to post the sizing information for what he has now, we could back-of-the-envelope figure out how much it costs to build against a few FPGA's and maybe get some theoretical bill-of-materials. There is speculative guesses based on previous sizing information from other projects ( http://pgate1.at-ninja.jp/SNES_on_FPGA/ )

Likewise, there are other solutions that haven't been explored as well. A FPGA on a PCIe card that has a console-cartridge/controller breakout box is more versatile, and could emulate the micomsoft sc-512n1-l/dvi aka SA7160 (which is already a FPGA) This card costs 400$ US. Micomsoft is also the company that makes the upscalers that people use which are also FPGA based.

Expecting a sub-99$ FPGA unit is wishful thinking, and people buying software emulators on ARM boards are being deceived. People rarely use these things as anything but toys for younger children. Hence the NES classic and presumably the SNES classic are just COTS (Cheap Off The Shelf) ARM parts. The latency tradeoff isn't nearly as bad with the Nintendo product as it is with the Pi-Pirates, but it's not a great experience either.

The key point about the light guns, I don't see any way for these games to be played with the original cartridge and light guns because these were designed for CRT's and short of OLED screen that emulates the CRT flicker, it's likely impossible, and the market is too little. Only the Wii had a controller that had the necessary electronics to do light gun games, and it used an infrared source outside the TV so that it didn't matter how big the TV was or if it was a CRT or LCD. So don't expect the games to ever come back in any form other than pirate sources on software emulators. At best, someone may figure out a way to configure a IR LED strip to emulate the 15Khz signal and use a Wiimote as the light gun.
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by tepples »

Kismet wrote:The key point about the light guns, I don't see any way for these games to be played with the original cartridge and light guns because these were designed for CRT's and short of OLED screen that emulates the CRT flicker, it's likely impossible, and the market is too little. Only the Wii had a controller that had the necessary electronics to do light gun games, and it used an infrared source outside the TV so that it didn't matter how big the TV was or if it was a CRT or LCD. So don't expect the games to ever come back in any form other than pirate sources on software emulators. At best, someone may figure out a way to configure a IR LED strip to emulate the 15Khz signal and use a Wiimote as the light gun.
A Wii Remote to light gun adapter exists. It just might be tricky to commercialize until 2026, when the Wii Remote patents expire. And it requires the console to continue to emit a 15.7 kHz luma signal, even if it's also producing an HD signal with completely different timing.
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Re: Introducing the VeriSNES (FPGA-based SNES)

Post by vanfanel »

Kismet wrote:
Expecting a sub-99$ FPGA unit is wishful thinking, and people buying software emulators on ARM boards are being deceived. People rarely use these things as anything but toys for younger children. Hence the NES classic and presumably the SNES classic are just COTS (Cheap Off The Shelf) ARM parts. The latency tradeoff isn't nearly as bad with the Nintendo product as it is with the Pi-Pirates, but it's not a great experience either.
Many errors here:
-Maybe for hardware with the complexity found on a SNES, a sub-99$ FPGA board is wishful thinking, but for smaller systems we have the VERY decent ZX-UNO, that makes NES, Atari 800XL, MSX1, ZX-SPECTRUM, BBC-MICRO, AMSTRAD CPC and C64. It can be bought today and you can even make your own provided you have the parts and tools.
-Pi-Pitrates? Kiss my originals.
And thanks to the dispmanx and drm/kms backends, emulaton on the Pi has FAR LESS input latency than that found on the NES-MINI: https://forums.libretro.com/t/an-input- ... ation/4407
You should get better informed next time.
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