HDMI CMVS?

Xian Xi · Mar 21, 2015

The Neo doesn't have a perfect 60hz signal, depending on the system it's usually either 59.18hz or 61.18hz. Can the FPGA just bump it to 60hz and if so, what kind of side effects would that cause?

kraquepype · Mar 21, 2015

Xian Xi said:
The Neo doesn't have a perfect 60hz signal, depending on the system it's usually either 59.18hz or 61.18hz. Can the FPGA just bump it to 60hz and if so, what kind of side effects would that cause?

Correct - in order to get a 60Hz signal the FPGA generates the clock signal in place of the crystal. The right pin of the crystal is lifted and replaced with the simulated clock output from the FPGA. This ensures display compatibility, and from what I can tell so far no real gameplay issues. The result is that the Neo is only slightly overclocked.

More details here:

https://github.com/charcole/NeoGeoHDMI/blob/master/Notes.md#overclocking

SmokeMonster · Mar 22, 2015

kraquepype said:
The question becomes, what is the best tradeoff? 720p output that could be more than the FPGA can handle, or a signal that not all displays handle natively? I'm also not sure what displays DON'T support 480p, so maybe this is all moot.)

720p is a lot safer. My new LG HDTV doesn't support 480p. Is there any way to implement a switch to select between 480P or 720p?

systmdfect · Mar 22, 2015

SmokeMonster said:
720p is a lot safer. My new LG HDTV doesn't support 480p. Is there any way to implement a switch to select between 480P or 720p?

When you say your TV doesn't support 480p, what exactly do you mean? It can't output in 480p or it just won't read an incoming 480p signal at all? A surprising number of people still have good old DVD players. I doubt the manufacturer would shoot themselves in the foot like that, unless you have a pretty high end television. Are you sure your TV won't just upscale the 480p to match one of its supported display resolutions?

SmokeMonster · Mar 23, 2015

systmdfect said:
When you say your TV doesn't support 480p, what exactly do you mean? It can't output in 480p or it just won't read an incoming 480p signal at all? A surprising number of people still have good old DVD players. I doubt the manufacturer would shoot themselves in the foot like that, unless you have a pretty high end television. Are you sure your TV won't just upscale the 480p to match one of its supported display resolutions?

480p input worked until the latest firmware release for it. Before all was well and I could input Dreamcast, etc through the VGA/RGB input. After the update though 480p or lower results in a black screen and "input error". There's no way to roll back the firmware either.

kraquepype · Mar 23, 2015

SmokeMonster said:
480p input worked until the latest firmware release for it. Before all was well and I could input Dreamcast, etc through the VGA/RGB input. After the update though 480p or lower results in a black screen and "input error". There's no way to roll back the firmware either.

That's not cool. I don't see how that would be intentional. It might be worth talking to the manufacturer or finding the release notes for the FW update.

Xian Xi · Apr 1, 2015

Anything new with this mod or is it now solid and good to go?

kraquepype · Apr 2, 2015

Nothing new really, its been running solid but some days at first boot I get interference that goes away if I power it off and on again. Its fully consolized now, I took it on a roadtrip to a friends house to play MOTW and it worked pretty good. His display had an issue but it cleared up after a few minutes.

I'm working on how to docs as well.

The project author is working on doing this on a MV1FS, and I wanted feedback from him on any issues.

I have 2 more FPGA boards coming and some female headers and PCBs to do a streamlined build I'm going to try on my 2 slot board.

I should be able to put both boards together if anyone is interested in giving it a shot.

clarkindustry · Apr 6, 2015

use tda 9980

Xian Xi · Apr 6, 2015

kraquepype said:
Nothing new really, its been running solid but some days at first boot I get interference that goes away if I power it off and on again. Its fully consolized now, I took it on a roadtrip to a friends house to play MOTW and it worked pretty good. His display had an issue but it cleared up after a few minutes.

I'm working on how to docs as well.

The project author is working on doing this on a MV1FS, and I wanted feedback from him on any issues.

I have 2 more FPGA boards coming and some female headers and PCBs to do a streamlined build I'm going to try on my 2 slot board.

I should be able to put both boards together if anyone is interested in giving it a shot.

I'll take one just to test it out. Shoot me a PM.

kraquepype · Apr 6, 2015

Xian Xi said:
I'll take one just to test it out. Shoot me a PM.

Cool once I get time to wire it up for my 2 slot for testing I'll send one your way.

What board will you be putting it on?

The original author got to start on his MV1FS implementation and was having a few issues, I'm sure they will get worked out.

kraquepype · Apr 6, 2015

clarkindustry said:
use tda 9980

What is a tda 9980? Details please?

Xian Xi · Apr 7, 2015

kraquepype said:
Cool once I get time to wire it up for my 2 slot for testing I'll send one your way.

What board will you be putting it on?

The original author got to start on his MV1FS implementation and was having a few issues, I'm sure they will get worked out.

Most likely an MV1C.

kraquepype · Apr 7, 2015

Xian Xi said:
Most likely an MV1C.

That should work, the SVC jamma board is similar to the MV1C.

I'll let you know once I get the new FPGAs in... It might be a few weeks before I get it all done though. Luckily I do have an SVC board to test on before I send it to you.

clarkindustry · Apr 8, 2015

kraquepype said:
What is a tda 9980? Details please?

TDA9981AHL/15/C180 - HDMI transmitter up to 150 MHz pixel rate with 3 x 8-bit video inputs and 4 x I2S-bus with S/PDIF, SOT315-1 Package, Standard Marking, Tray Dry Pack, Bakeable, Single

daybona · Apr 8, 2015

I'm very curious to see how this turns out. A Neo that outputs a true digital hd signal would be amazing!

XtraSmiley · Jun 14, 2015

Any update to this?

Xian Xi · Jun 14, 2015

I forgot to ask about this as well.

GTRetro87 · Jun 23, 2015

Now this is something I'm down to put some $$ towards

kraquepype · Jun 24, 2015

Hey guys, sorry for not replying sooner... It's been hard to do anything inside lately since the weather got warmer and things have been quite hectic lately. (I could go into more detail but won't... enough excuses...)

There was a code update from Charlie recently that resolved the issue with lines on the left side that happened on certain games, so the picture it looking pretty good.

The weird sync problem on my MV-1B is still there but it resolves after being fired up for a few minutes. (This might not be an issue on other boards)

There is still the problem with some sounds not getting through (Credit sounds, character select chimes, etc) that have to do with a seperate sound channel (SSG - Simple Sound Generator) that is added to the sound output outside of the main DAC. It would have to be mixed in somehow or the analog audio would need to be converted before going to the FPGA.

I still need to wire up my 2 slot and put together a board for Xian Xi ... If I get some free time I'll try to get that going but won't be for a few weeks most likely.

I'd love to design a PCB that could attach directly to the FPGA board with a header for the MVS wiring and a HDMI jack to simplify things, but I have no experience with PCB design.

XtraSmiley · Sep 12, 2015

Fresh bump, any progress?

Xian Xi · Sep 15, 2015

I still am interested in doing this but I need a "for idiots" version.

kraquepype · Sep 17, 2015

I've still got 2 FPGA boards waiting for me to mess with

I still haven't figured out how to account for the SSG, without it you get most sounds but not having coin or character select sounds bugs me.

When I get some time I'll try to put a how-to together for what I've done, that might get more people tinkering.

Unfortunately I don't think this will ever be a turn-key type solution - I don't have the time to dedicate to it.

I hope I can make it a little easier though.

...

XtraSmiley · Jan 12, 2016

New year bump. Any progress?

Xian Xi · Jan 12, 2016

kraquepype said:
I've still got 2 FPGA boards waiting for me to mess with

I still haven't figured out how to account for the SSG, without it you get most sounds but not having coin or character select sounds bugs me.

When I get some time I'll try to put a how-to together for what I've done, that might get more people tinkering.

Unfortunately I don't think this will ever be a turn-key type solution - I don't have the time to dedicate to it.

I hope I can make it a little easier though.

...

Analog audio is just a 3rd channel that can be summed to the L and R channels.

HDMI CMVS?

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