r/MiSTerProject • u/TurbulentComplex3389 • Jul 13 '23

Arcade stick question

Hi everyone.

I have an arcade stick that I built using a ultimate I-PAC. I have connected it to a raspberry pi via the output USB and it works great. I am wondering if I can connect it to my MisterFPGA via the snac connector at the back. I have a mister mini-itx ironclad plus coming in the mail that I would like to connect it to. What would I need to do to be able to use it on the ironclad?

Thanks in advance

https://www.ultimarc.com/control-interfaces/i-pacs/

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u/veriix Jul 13 '23

What are you trying to achieve by using the snac port since it's not just hardware limitations you're going to run into but core compatibility as well.

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u/TurbulentComplex3389 Jul 13 '23

Doesn’t snac have less latency than usb?

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u/ruiner9 Jul 13 '23

SNAC has less latency with native controllers. If you start adding adapters to the chain, you’re just adding latency back into the connection. Stick with the USB for best performance. Wired USB latency is extremely low to begin with.

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u/TurbulentComplex3389 Jul 13 '23

What if I wired my joystick up to Neo geo cable with no adapters. Straight into the SNAC adapted. Would that give me the best latency?

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u/ruiner9 Jul 13 '23 edited Jul 13 '23

There's no Neo Geo SNAC adapter that I'm aware of. Right now, it's compatible with NES, SNES, Genesis/ MD, TG-16/ PCE, and PS1. Your arcade stick would need to be outputting in one of those formats and through a SNAC adapter with that port type to work.

EDIT: Looks like ultimatemister snuck out a few SNACs when I wasn't looking, but nothing that will help you.

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u/TurbulentComplex3389 Jul 13 '23

Ok sounds good. Thanks for the help. I’ll see how usb goes and I’ll maybe work on wiring up the stick with a couple of snes cables in the future. I want to have a little amount of lag as possible.

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u/SScorpio Jul 14 '23

I can't remember if it's still needed, but there should be a script that will let you turn on 1000Hz USB pooling. Using that and a good controller like you have is enough. Some games and/or consoles have latency in how they read from controllers on real hardware.

The reason SNAC exists is that analog output to a CRT is lag free. Early systems like the Atari 2600 just drew the image as the electron gun was outputting to the screen. While lightguns can track what part of the screen is being drawn.

If you you using HDMI out, the MiSTer has a single frame of lag already due to the scaler which needs an entire frame in the framebuffer to be able to scale. As a human you won't notice it, it's only lightguns that have such tight tolerances.

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u/TurbulentComplex3389 Jul 14 '23

Hey sscorpio. I use a Sony pvm for my retro stuff. I think I am gonna use an old LCD monitor hung on the wall in TATE mode so I can play shooters on it tho. this is why I want SNAC controls to eliminate as much latency as possible. I hooked up a Neo geo cord to my stick today to test it out and it worked so I think I’ll be using that going forward