NES/SNES 240p dejitter mod

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thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Arthrimus wrote:
dadjumper wrote:Is there anywhere I can buy a pre-flashed board? I'd love to solve my jitter issues with the OSSC, but I don't quite have the know-how to flash the firmware etc.
thebigcheese wrote: I would also love to buy a pre-assembled board. Mostly out of laziness. Side question, if I have an RGB bypass board (Voultar's kit) for my SNES 1-chip (a Jr model), would the steps change at all? Sync is fed through the bypass board, so I am assuming I would run sync through this first and then into the bypass board, but maybe it would just run directly to the output instead?
I'm about to order and build some of the v1.2 boards this week. I could build a couple extra if anyone wants one. PM me if you're interested, I'll probably be making my parts order tomorrow.
Excellent, PM sent.
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James-F
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Re: NES/SNES 240p dejitter mod

Post by James-F »

marqs wrote:It should be now good enough for mass-manufacturing.
That's great!
Gotta have at least one unit with this.
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Any chance for an NES install guide? Specifically for a toploader. The SNES seems pretty straightforward, but I'd also like to sort out my NES while I'm at it. I suppose there haven't been any updates about a potential NESRGB fix?
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dadjumper
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Re: NES/SNES 240p dejitter mod

Post by dadjumper »

thebigcheese wrote:
Arthrimus wrote:
dadjumper wrote:Is there anywhere I can buy a pre-flashed board? I'd love to solve my jitter issues with the OSSC, but I don't quite have the know-how to flash the firmware etc.
thebigcheese wrote: I would also love to buy a pre-assembled board. Mostly out of laziness. Side question, if I have an RGB bypass board (Voultar's kit) for my SNES 1-chip (a Jr model), would the steps change at all? Sync is fed through the bypass board, so I am assuming I would run sync through this first and then into the bypass board, but maybe it would just run directly to the output instead?
I'm about to order and build some of the v1.2 boards this week. I could build a couple extra if anyone wants one. PM me if you're interested, I'll probably be making my parts order tomorrow.
Excellent, PM sent.
Same here, thanks!
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

thebigcheese wrote:Any chance for an NES install guide? Specifically for a toploader. The SNES seems pretty straightforward, but I'd also like to sort out my NES while I'm at it. I suppose there haven't been any updates about a potential NESRGB fix?
I'll be installing one of those v1.2 boards on my original Famicom once they arrive.
beast1x5
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Re: NES/SNES 240p dejitter mod

Post by beast1x5 »

I could totally use a dejitter board myself
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unmaker
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Re: NES/SNES 240p dejitter mod

Post by unmaker »

I'm interested in building one of these myself. I actually have 3 version 1.1 boards already and I need to order the parts. What I'm confused on though is this:

-Hardware

-OpenOCD supported JTAG programmer (e.g. FT2232 based)

Would someone mind linking a suitable programmer? Preferably as cheap as possible. I have an Altera USB Blaster but I don't think that'll work for this.
ebeb
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Re: NES/SNES 240p dejitter mod

Post by ebeb »

unmaker wrote:I'm interested in building one of these myself. I actually have 3 version 1.1 boards already and I need to order the parts. What I'm confused on though is this:

-Hardware

-OpenOCD supported JTAG programmer (e.g. FT2232 based)

Would someone mind linking a suitable programmer? Preferably as cheap as possible. I have an Altera USB Blaster but I don't think that'll work for this.
I programmed mine with a Raspberry Pi; works pretty well.
https://movr0.com/2016/09/02/use-raspbe ... d-adapter/
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

So looking at the different installs, it seems like different components that need to be removed and different solder points for the wires for each revision... Is there some general guidance we should be looking for? I have an NTSC SNES Jr and NTSC NES-101 I want to use these with, but schematics are hard to find for anything Nintendo and I'm not really sure what to be looking for. I know Marqs said he would add some info for the Famicom, but I don't think that really helps my situation, either...
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

A major challenge of this project has been making the board universal for all NES/SNES revisions, potentially including DFO etc mods. There's certainly a general guideline on how the board is installed (replace original clocking circuit, tap PPU-generated sync signal, hook up de-jittered c-sync to output), but the details are case-specific. I've now assembled a couple v1.2 boards so I'll be installing one to a Famicom soon. Meanwhile, you could try tracing out NES-101 clock circuit and check how much it matches this schematic (which seems to have a couple errors).
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

thebigcheese wrote:So looking at the different installs, it seems like different components that need to be removed and different solder points for the wires for each revision... Is there some general guidance we should be looking for? I have an NTSC SNES Jr and NTSC NES-101 I want to use these with, but schematics are hard to find for anything Nintendo and I'm not really sure what to be looking for. I know Marqs said he would add some info for the Famicom, but I don't think that really helps my situation, either...
I should have SNES jr. specific installation instructions put together soon. I have a SNES Jr. coming in the mail so I'll pass my findings on to Marqs and he could add them to the Github if he is satisfied with the results. I don't expect the install to be substantially different than the 1CHIP boards except for the RGB mod that needs to be done.

I'm also looking for a NES to use as a guinea pig for this mod as well, if I get that done in a timely fashion I'd be happy to share my results there as well.
plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances

I install and sell mods at arthrimus.com | SNES RGB Bypass+Dejitter available now! | Watch me live stream my work on YouTube
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Thanks! I have been looking over the schematics for the other SNES systems to compare and I think I more or less have it figured out, but wasn't going to really dive in until I get the boards. For the NES-101... once the Famicom stuff is up, that might give me something to go off. Or I suppose I could roughly base it off of where things are connected on the SNES schematics. But I've got the NESRGB in there and an RGB mod in the Junior, so that naturally complicates things. I assume I am basically just fixing sync before it gets to the mod boards, ie sending it to the dejitter board, then from that to the mod?
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keropi
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Re: NES/SNES 240p dejitter mod

Post by keropi »

kind of late to the party but is there a place to get this mod either complete or in kit form - but with the fpga programmed?
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Arthrimus
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Re: NES/SNES 240p dejitter mod

Post by Arthrimus »

keropi wrote:kind of late to the party but is there a place to get this mod either complete or in kit form - but with the fpga programmed?
I put together a small batch of V1.2 boards over last weekend. I still have some extras that I could let go of. PM me if you are interested.
plus ça change,
plus c'est la même chose,
The more that things change,
The more they stay the same.- RUSH- Circumstances

I install and sell mods at arthrimus.com | SNES RGB Bypass+Dejitter available now! | Watch me live stream my work on YouTube
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

Instructions for SNS-CPU-1CHIP-02 (identical to SNS-CPU-1CHIP-01) and SNN-CPU-01 has been added to the repo. I've also now installed the board inside Famicom by removing 220p and 51p caps from clock lines going to CPU/PPU and wiring MCLK_o (with resistor divider enabled) to the sides which go to chips while getting CSYNC_i from CS# of NESRGB. While that seems to work in principle, I'm getting some noise issues (especially on 3.3V supply which is strange) that need to be resolved before the installation can be considered stable.
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Awesome, thanks! Just installed in my junior and it's working great. FYI, you can also tap c-sync off the via two to the left of the vias you used for RGB, much easier and it works fine. I've got 5x running on the OSSC with no issues now.
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

I got a tip and verified that the problem with Famicom was caused by a counterfeit regulator. Adding a large cap on 3.3V line eliminated oscillation and remaining minor noise seen on scope did not cause issues. A second hurdle was that CSYNC from NESRGB's comparator wasn't reliably captured initially as latching occurred too close to signal transition, but enabling "reduced MC power" option of the CPLD (slighly increasing delay of MCLK_o and signals launched by it) fixed that. Now everything seems to run stable - I'll add instructions and updated SVF for Famicom in a few days.

One general note has been made about CSYNC_o level which currently does not 100% match the output by vanilla SNES c-sync, mainly due to CPLD output logic high being closer to 4V than 5V. Replacing R10 (3.3k) with 8.2k resistor brings the output to same level, and that change is already applied on the first batch of pre-assembled boards which is available soon.
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keropi
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Re: NES/SNES 240p dejitter mod

Post by keropi »

marqs, how can someone order one of those boards that will be available soon?
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Marqs, does the change to R10 do much? That is, if I'm already getting good picture and sync with my PVM and OSSC, would changing it actually have any benefit for me?
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

keropi wrote:marqs, how can someone order one of those boards that will be available soon?
They'll be sold through Videogameperfection.com.
thebigcheese wrote:Marqs, does the change to R10 do much? That is, if I'm already getting good picture and sync with my PVM and OSSC, would changing it actually have any benefit for me?
No need to do that if everything works fine. For those who have 470ohm series resistor on the cable, resulting sync level (with original R10) ends up a bit lower that nominal 0.3Vpp which is why the change was made.
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

Installation instructions for Famicom HVC-CPU-07 has been added to the repo. The method for other FC/NES models should be mostly similar. OP has also been updated with relevant links.
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keropi
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Re: NES/SNES 240p dejitter mod

Post by keropi »

I have a question about this :mrgreen:
ATM I have 3 multisync monitors that are capable of 15~40khz in both analog and digital formats and I prefer to use them since I also like my old pc CGA/EGA stuff. SNES with the stock c-sync signal mess with the monitors and you cannot get a usable display but If I pass the signal through a LM1881 (or strip composite) it works.
So my question is: if I install one of the new RGB bypass boards that also has a 4th channel for c-sync will it work or I would need the dejitter board as well? ATM I have installed bortie's RGB bypass that uses the 7314 so it's only 3 channels.

Thanks for any info!
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maxtherabbit
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Re: NES/SNES 240p dejitter mod

Post by maxtherabbit »

keropi wrote:I have a question about this :mrgreen:
ATM I have 3 multisync monitors that are capable of 15~40khz in both analog and digital formats and I prefer to use them since I also like my old pc CGA/EGA stuff. SNES with the stock c-sync signal mess with the monitors and you cannot get a usable display but If I pass the signal through a LM1881 (or strip composite) it works.
So my question is: if I install one of the new RGB bypass boards that also has a 4th channel for c-sync will it work or I would need the dejitter board as well? ATM I have installed bortie's RGB bypass that uses the 7314 so it's only 3 channels.

Thanks for any info!
I wouldn't think running the sync through an amp like the THS7374 would do anything to help you, could be wrong though
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keropi
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Re: NES/SNES 240p dejitter mod

Post by keropi »

well, feeding it to the LM1881 makes it work (feeding c-sync to the sync stripper in other words) so maybe the 7374 could also attenuate it or something so the monitors can sync to it ... it seems I'll just have to test it.
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Syntax
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Re: NES/SNES 240p dejitter mod

Post by Syntax »

Most RGB bypass kits have the choice to attenuate the buffered csync to 75R standards or leave it at 5v TTL.

You want 5v TTL and a 330-470R resistor on the sync line when using it with non TTL equipment. (330 for stock ntsc SNES 470 for bypass board I think, but check)

A stripper will add delay to the sync line and move your image left or right.
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

keropi wrote:well, feeding it to the LM1881 makes it work (feeding c-sync to the sync stripper in other words) so maybe the 7374 could also attenuate it or something so the monitors can sync to it ... it seems I'll just have to test it.
Which multisync monitors are you using and are you feeding sync to a TTL sync input? LM1881 doesn't help with sync jitter, and I doubt your problem is related to that. However, LM1881 sync output is 5Vpp while c-sync level (to unterminated input) of SNES is 2.4Vpp, which is still technically TTL but possibly not high enough for some monitors' sync inputs..
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Marqs, I found a schematic for the original Famicom (which is, I believe, the one used in your example) and have tracked down the components you removed in the instructions. In order for me to translate this to my toploader, I just want to verify something. It looks like C4 and C9 are used on either end of a connection between pin 29 of the CPU and pin 18 of the PPU. When you remove these and jumper the pads, I am assuming you are doing this to basically bypass the circuit in between and connect those pins directly, is that correct? So effectively, pin 29 of the CPU and pin 18 of the PPU are directly connected to each other after modding, right?

Edit: Hmm, actually, looking at my NES-101, those two pins are already directly connected. It looks like they connect together and then from there to a capacitor (that I think connects to the oscillator circuit). So I am not sure what's going on. Maybe the schematic I have is numbered weird or maybe that's not what I need to do?
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

thebigcheese wrote:Marqs, I found a schematic for the original Famicom (which is, I believe, the one used in your example) and have tracked down the components you removed in the instructions. In order for me to translate this to my toploader, I just want to verify something. It looks like C4 and C9 are used on either end of a connection between pin 29 of the CPU and pin 18 of the PPU. When you remove these and jumper the pads, I am assuming you are doing this to basically bypass the circuit in between and connect those pins directly, is that correct? So effectively, pin 29 of the CPU and pin 18 of the PPU are directly connected to each other after modding, right?
Yes, by removing the caps the original clock circuit is disconnected. MCLK_o (from snes_dejitter) is hooked to PPU pin 18 thru NESRGB adapter board (assuming you install it the same way), so you then only need to connect it to CPU pin 29 which is the reason for the jumper wire.
thebigcheese wrote:Edit: Hmm, actually, looking at my NES-101, those two pins are already directly connected. It looks like they connect together and then from there to a capacitor (that I think connects to the oscillator circuit). So I am not sure what's going on. Maybe the schematic I have is numbered weird or maybe that's not what I need to do?
Maybe NES-101 already has CPU and PPU driven by a common driver, would be typical for Nintendo to save a few parts on late revision model.
thebigcheese
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Re: NES/SNES 240p dejitter mod

Post by thebigcheese »

Yeah, I tracked it as best I can and it does seem to be the case. In that case, should I just remove the single capacitor to disconnect from the circuit? Since they are already connected, I imagine that would be all. And the oscillator, of course.

With regards to programming the dejitter board, I've got one that needs to be updated with the new NES update. Can I not just flash directly from Quartus (using my Altera USB Blaster)? It seems like I can open the POF file there and flash directly, but maybe I am not understanding how it works (which wouldn't be surprising, I'm a novice). If I am to use Open OCD, would I then use the SVF you posted in the project or do I need to compile my own per the instructions?
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marqs
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Re: NES/SNES 240p dejitter mod

Post by marqs »

thebigcheese wrote:Yeah, I tracked it as best I can and it does seem to be the case. In that case, should I just remove the single capacitor to disconnect from the circuit? Since they are already connected, I imagine that would be all. And the oscillator, of course.
Yes, that should work. Removal of original crystal is not strictly necessary, but doing so removes one potential noise source and saves a bit of power.
thebigcheese wrote:With regards to programming the dejitter board, I've got one that needs to be updated with the new NES update. Can I not just flash directly from Quartus (using my Altera USB Blaster)? It seems like I can open the POF file there and flash directly, but maybe I am not understanding how it works (which wouldn't be surprising, I'm a novice). If I am to use Open OCD, would I then use the SVF you posted in the project or do I need to compile my own per the instructions?
I don't think you can program it from Quartus (extra settings are added during pof2jed conversion), but you might be able to use USB Blaster with OpenOCD to program the SVF from repo. However, USB Blaster does not supply power so you'd need to externally provide 5V for the board and 3.3V/5V for USB Blaster's V_target pin (check your model's JTAG voltage support).
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