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SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 9:43 am
by nymous

Hi. I've tried to google that question, but didn't find any answer. Can someone explain what's this adapater for? I saw it in several shops and on Aliexpress of course. What does it do? It has USB3 on both sides. Is it a kind of debug board? A level converter? Why is there a jumper and a connector on it?


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 11:54 am
by AngelicLiver

It is a level shifter. It is used to convert 3.3v logic to 5v peripherals. There's a good explanation here. As with anything on the user port; it may have a USB connector but it is not carrying USB signals. Do not try to connect USB devices to the user port.


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 2:29 pm
by nymous

No-no, I understand it's not an USB. Just wondering why do I need it with MiSTer. So it is a level shifter for 5V devices. Is there any list of which devices I should use with it?


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 2:49 pm
by nymous

Still, what the jumper do?


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 5:57 pm
by C-R-T
nymous wrote: Sat Dec 23, 2023 2:49 pm

Still, what the jumper do?

I’ve tried asking that before. Apparently it’s a secret.

But the board itself is the standard snac board. Without it you’ll get no snac functionality.


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 23, 2023 6:17 pm
by Flandango

The jumper enables/disables the IO6 line.


Re: SNAC adapter with USB on both sides?

Posted: Sun Dec 24, 2023 9:19 am
by nymous
C-R-T wrote: Sat Dec 23, 2023 5:57 pm

But the board itself is the standard snac board. Without it you’ll get no snac functionality.

The problem is, all my controllers work without it just fine, this is why i'm asking. I've tried NES, NES Zapper, SNES, Genesis and PC Engine. Though I've heard that some users have problems with NES controllers without it.


Re: SNAC adapter with USB on both sides?

Posted: Wed Dec 27, 2023 9:14 am
by FPGA64
nymous wrote: Sun Dec 24, 2023 9:19 am
C-R-T wrote: Sat Dec 23, 2023 5:57 pm

But the board itself is the standard snac board. Without it you’ll get no snac functionality.

The problem is, all my controllers work without it just fine, this is why i'm asking. I've tried NES, NES Zapper, SNES, Genesis and PC Engine. Though I've heard that some users have problems with NES controllers without it.

Why they may appear to work you are risking damage to the DE10 or the Controller. The level shifters take the voltage being supplied or coming in and adjust it to the logic level of the device. Without them you could be ewither undervolting the controller or overvolting the DE10.

This explains the Jumper

https://misterfpga.co.uk/sega-genesis-c ... nac-setup/


Re: SNAC adapter with USB on both sides?

Posted: Wed Dec 27, 2023 4:36 pm
by nymous
FPGA64 wrote: Wed Dec 27, 2023 9:14 am

Why they may appear to work you are risking damage to the DE10 or the Controller. The level shifters take the voltage being supplied or coming in and adjust it to the logic level of the device. Without them you could be ewither undervolting the controller or overvolting the DE10.

Yeah, I understand that. Unfortunately it's not very articulated anywhere, most (aliexpress) shops even skip the explanation totally.


Re: SNAC adapter with USB on both sides?

Posted: Wed Dec 27, 2023 7:37 pm
by FPGA64
nymous wrote: Wed Dec 27, 2023 4:36 pm
FPGA64 wrote: Wed Dec 27, 2023 9:14 am

Why they may appear to work you are risking damage to the DE10 or the Controller. The level shifters take the voltage being supplied or coming in and adjust it to the logic level of the device. Without them you could be ewither undervolting the controller or overvolting the DE10.

Yeah, I understand that. Unfortunately it's not very articulated anywhere, most (aliexpress) shops even skip the explanation totally.

I wouldnt touch an Ali Express store, other than Retrocastle, in any way.


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 30, 2023 5:47 pm
by jd213

RetroCastle does sell SNAC adapters, but I don't see the level shifter.
https://www.aliexpress.us/item/3256803697539804.html

I assume their PS1 SNAC would be safe to use without it though, since PS1 controllers use 3.3v.


Re: SNAC adapter with USB on both sides?

Posted: Sat Dec 30, 2023 7:44 pm
by FPGA64
jd213 wrote: Sat Dec 30, 2023 5:47 pm

RetroCastle does sell SNAC adapters, but I don't see the level shifter.
https://www.aliexpress.us/item/3256803697539804.html

I assume their PS1 SNAC would be safe to use without it though, since PS1 controllers use 3.3v.

His adaptor has them built into the board


Re: SNAC adapter with USB on both sides?

Posted: Sun Dec 31, 2023 3:12 pm
by jd213

Ah OK, that makes sense considering they're a bit more expensive than other SNAC adapters on Aliexpress.


Re: SNAC adapter with USB on both sides?

Posted: Wed Jan 10, 2024 11:32 am
by neogeo81

Just as info: All SNAC adapters from UltimateMister don't need this.


Re: SNAC adapter with USB on both sides?

Posted: Wed Jan 10, 2024 3:28 pm
by antibolo

Is it safe to chain two level shifters?

I ask because the Multisystem user port claims to have a built-in level shifter according to its manual, and I ordered a SNAC adapter from UltimateMister which apparently also has one. I haven't received it yet, but I'm still confused on how all that will interact.


Re: SNAC adapter with USB on both sides?

Posted: Wed Jan 10, 2024 11:47 pm
by Missus
antibolo wrote: Wed Jan 10, 2024 3:28 pm

Is it safe to chain two level shifters?

I ask because the Multisystem user port claims to have a built-in level shifter according to its manual, and I ordered a SNAC adapter from UltimateMister which apparently also has one. I haven't received it yet, but I'm still confused on how all that will interact.

You can disable the onboard level shifters. Thats how the MMS can use either User3.3v and Snac5v. Details are in the manual


Re: SNAC adapter with USB on both sides?

Posted: Thu Jan 11, 2024 4:07 pm
by neogeo81
antibolo wrote: Wed Jan 10, 2024 3:28 pm

Is it safe to chain two level shifters?

I ask because the Multisystem user port claims to have a built-in level shifter according to its manual, and I ordered a SNAC adapter from UltimateMister which apparently also has one. I haven't received it yet, but I'm still confused on how all that will interact.

you can disable it with the pin and switch on it AND most important you don't need to use it in the first place since it has one built in. just plug the SNAC controller adapters directly to your MMS.


Re: SNAC adapter with USB on both sides?

Posted: Thu Jan 11, 2024 4:14 pm
by antibolo
Missus wrote: Wed Jan 10, 2024 11:47 pm
antibolo wrote: Wed Jan 10, 2024 3:28 pm

Is it safe to chain two level shifters?

I ask because the Multisystem user port claims to have a built-in level shifter according to its manual, and I ordered a SNAC adapter from UltimateMister which apparently also has one. I haven't received it yet, but I'm still confused on how all that will interact.

You can disable the onboard level shifters. Thats how the MMS can use either User3.3v and Snac5v. Details are in the manual

The manual is not clear on what you're supposed to do when the SNAC device has a built-in level shifter.

From what I can gather, I should set SW7 (the front switch) to the IO6 position (as mentioned in the UltimateMister product page), and set the jumper J17 to the 3.3v position (presumably to disable the onboard level shifter), is that correct?