nesdev.org

anyone making a fpga snes with hdmi?

VeriSNES appears to be the most promising project.

VeriSNES shows promise in this regard, however keep in mind that:

1. The way the FPGA NES projects work are not 100% accurate (tiny underclock by 0.164167% (60.098 to 60)) for speed to avoid creating latency in upscale, this may also be true for SNES

2. The SNES interfaces are 5V, while FPGA's are not, thus level shifters are required on the cartridge interface, controllers and expansion interface (if a real expansion device is used.) So it is not known yet if it will work with expansion-chip games.

3. When paired with a SD2SNES, there's not yet a way to pass digital audio through the FPGA to avoid having to add an ADC. For things like the Super Gameboy and various "run X console games on your SNES" add-ons that ADC would still need to be present. The easiest solution, really, is for the SD2SNES to identify that it is running on VeriSNES and somehow pass the audio digitally when audio is being generated on the chip (MSU-1) instead of in Analog form. This would require that both projects collaborate. An alternate option is to simply implement the SD2SNES in the same FPGA, though at that point, may as well just tick every line on the wishlist and pick a FPGA capable of emulating the SA-1 as well.


The HDMI NES projects also picked as low-powered FPGA's as possible, and thus getting 1080p out of one project is impossible, while the other can do it, but costs twice as much. So this has some interesting implications for a SNES. If you want to support 720p only and no expansion-chip games, a much cheaper FPGA may be usable. But if you want to support expansion chips, and all resolutions (720p, 1080p, 2160p, 4320p, etc) without adding a lag-inducing framebuffer, a much more expensive FPGA would be required that has more block memory in the FPGA itself.

VeriSNES is being developed on a Terasic DE2-115 which costs around $600 (Cyclone IV FPGA with 114,480 Logic Elements and 3.9Mbits of RAM), someone who previously used the exact same board http://pgate1.at-ninja.jp/SNES_on_FPGA/rpt_DE2-115.htm fit the SNES into 28,417 LE's and 2,141,376 bits of Memory. But this doesn't include creating a HDMI interface.

The EP4CE115F29C7 alone costs 426.70 each, and are no longer stocked by various electronics places. The minimum FPGA that would fit the SNES as per that fitting report without taking into account the extra needed HDMI interface is EP4CE55F23C8N (Cyclone IV E) which costs $115.40

So minimally, it is looking like 115.40 a FPGA to emulate the SNES chips. Assuming you could acquire the controller ports and shielded cartridge interface cheaply. The OSCC (aka x-RGB) uses a EP4CE55F23C8N (15408 LE, 516096 Bits RAM) which costs 23.14. So it's likely this can all be done in the same FPGA. You still need chips for firmware to load the FPGA.

what's in accurate with the fpga nes exactly?

supermario4 wrote:what's in accurate with the fpga nes exactly?

See https://forums.nesdev.com/viewtopic.php ... 13#p136413 about the NES PPU underclock.

With a SNES, the same thing may be required as a real SNES outputs the same frequency on RGB output. You can read about issues involving RGB mods/line-doublers with the SNES due to this. The NES and SNES output 60.098 in NTSC when the correct frequency is 59.94 , this is just enough to break some capture equipment, and is a crap-shoot with flat-panel TV's. Computer monitors typically expect 60hz.

https://www.videogameperfection.com/201 ... r-verdict/

SNES/Super Famicom – The SNES/Super Famicom is certainly the system that causes the most issues with the OSSC. On most TVs and every computer monitor we’ve tested so far, the image is great, with no noise whatsoever and just the tiniest hint of jitter if you really get your nose up against the screen. Unfortunately, on some TVs the system simply does not work and it’s impossible to get a stable picture. Marqs is still investigating some workarounds for this problem and hopefully they will be fixed in a future firmware.

Kismet wrote:Computer monitors typically expect 60hz.

Pedantic moment:

Computer monitors are usually "multisync", even modern LCD ones, and can accept input any almost any arbitrary constant vsync rate.

It's when the monitor includes an analog NTSC sampler/upscaler that everything goes banana shaped, because those devices usually expect an exact 50, 59.94, or 60Hz vsync rate.

Kismet in simple terms what does the underclocked nes do to games exactly?

They run very, very slightly slower.

so not noticeable then?

Probably not, unless you're timing something specific with a clock. Like I think we're talking about losing a second every 20 minutes?

rainwarrior wrote:Probably not, unless you're timing something specific with a clock. Like I think we're talking about losing a second every 20 minutes?

Assuming my math is correct, you'd lose 60 frames (1 second's worth) in about 10 mins and 12 seconds. It's a 0.16% difference.
Even still, Unless you're a speedrunner and every frame matters, or doing a side-by-side comparison, I doubt you could tell a difference.

tepples wrote:VeriSNES appears to be the most promising project.

how long until it's works all games years,months etc?

lidnariq wrote:

Kismet wrote:Computer monitors typically expect 60hz.

Pedantic moment:

Computer monitors are usually "multisync", even modern LCD ones, and can accept input any almost any arbitrary constant vsync rate.

It's when the monitor includes an analog NTSC sampler/upscaler that everything goes banana shaped, because those devices usually expect an exact 50, 59.94, or 60Hz vsync rate.

The typical upscaler (eg XRGB, OSSC) has problems with non-59.94, which tend to show up mostly in the NES/SNES. You're right though, the computer monitor typically has more tolerance, however if you read the specs for current models of monitors, they typically will only mention 60hz for DP or DVI/VGA, and only support 25,29.97,30,59.94 on HDMI since those are "TV" modes.

supermario4 wrote:

tepples wrote:VeriSNES appears to be the most promising project.

how long until it's works all games years,months etc?

That's not a determinable answer as it's in development and currently:
- Still exists only on a development board, so we have no idea about it's ability to connect to HDMI since the development board only has VGA
- Currently doesn't have sprites, so right now you would only be able to fumble through a few games (eg Wolfenstien) that uses mostly BG modes.
- No idea right now if it can interface with a real cartridge, or expansion chip games

That's the gist of what I was able to read from VeriSNES's updates and the video's posted.

A "hardware" based emulation will be more accurate than a software emulator, but even then there are compromises that need to be made to make it work with HDMI, expansion chips, and expansion devices. I don't expect someone to just grab the Verilog files and turn around and start selling $200 SNES clones, because there is not a large market for that, (a working "clean" SNES goes for $80 on eBay, a broken one for parts goes for $30.)

However I do expect that eventually (maybe 4 years out from now) some kind of "universal console platform" will be designed that would let you connect original cartridges and controllers to new "base units" that would let you emulate any 8 or 16 bit console/computer that ever existed. Single-machine FPGA units are too expensive just to emulate one machine. There are current attempts right now for computers and arcade machines, but they largely rely on old-stock parts (which is how the Analogue NT started) instead of emulating all the chips. Eventually they will all realize that a common FPGA platform would bring down the unit cost on the FPGA.

Kismet wrote:

lidnariq wrote:

Kismet wrote:Computer monitors typically expect 60hz.

Pedantic moment:

Computer monitors are usually "multisync", even modern LCD ones, and can accept input any almost any arbitrary constant vsync rate.

It's when the monitor includes an analog NTSC sampler/upscaler that everything goes banana shaped, because those devices usually expect an exact 50, 59.94, or 60Hz vsync rate.

The typical upscaler (eg XRGB, OSSC) has problems with non-59.94, which tend to show up mostly in the NES/SNES. You're right though, the computer monitor typically has more tolerance, however if you read the specs for current models of monitors, they typically will only mention 60hz for DP or DVI/VGA, and only support 25,29.97,30,59.94 on HDMI since those are "TV" modes.

supermario4 wrote:

tepples wrote:VeriSNES appears to be the most promising project.

how long until it's works all games years,months etc?

That's not a determinable answer as it's in development and currently:
- Still exists only on a development board, so we have no idea about it's ability to connect to HDMI since the development board only has VGA
- Currently doesn't have sprites, so right now you would only be able to fumble through a few games (eg Wolfenstien) that uses mostly BG modes.
- No idea right now if it can interface with a real cartridge, or expansion chip games

That's the gist of what I was able to read from VeriSNES's updates and the video's posted.

A "hardware" based emulation will be more accurate than a software emulator, but even then there are compromises that need to be made to make it work with HDMI, expansion chips, and expansion devices. I don't expect someone to just grab the Verilog files and turn around and start selling $200 SNES clones, because there is not a large market for that, (a working "clean" SNES goes for $80 on eBay, a broken one for parts goes for $30.)

However I do expect that eventually (maybe 4 years out from now) some kind of "universal console platform" will be designed that would let you connect original cartridges and controllers to new "base units" that would let you emulate any 8 or 16 bit console/computer that ever existed. Single-machine FPGA units are too expensive just to emulate one machine. There are current attempts right now for computers and arcade machines, but they largely rely on old-stock parts (which is how the Analogue NT started) instead of emulating all the chips. Eventually they will all realize that a common FPGA platform would bring down the unit cost on the FPGA.

but the avs exists so how's it not possible to have it as a product then?

For one thing, there's far less logic in an NES CPU and PPU than in a Super NES S-CPU, S-PPU1, S-PPU2, S-SMP, and S-DSP. This means it can all fit in a less expensive FPGA.

For another, the NES CPU and PPU have been decapped, delayered, photographed, and simulated, allowing white-box testing of low-level details. See "Visual 2A03" and "Visual 2C02". The Super NES custom parts have not yet.