SNES -> Atari adapter doesn't work

[danboid]

I have a SNES controller to Atari adapter that works fone with my Amiga but I get a steady, frequent beep every few seconds when I plug it into my xberry pi. No error is printed to the screen but clearly its not happy.

I have my XB configured to use MD style controllers, which I thought would work with my SNES to Atari adapter.

Any suggestions?

[danboid]

This is the beeping thing:

[Pobulous]

Could it be drawing too much power from the 5V pin?

[Seven.FFF]

The Xberry Pi, like Nexts and N-GOs, uses megadrive/genesis wiring and select mux protocol. This means that it puts +5V on pin 5, second fire on pin 9, and pin 7 is an output pin carrying a strobed 3.3V low current logic clock signal for select, that moves a state machine in the controller through different states that represent the extra buttons.

Atari is a bit too much of a loosey-goosey term to have a precise meaning, as there are so many different wirings that were based on Atari wiring but changed it or extended it. In its original VCS 2600 form, Atari wiring has +5V on pin 7, and analogue paddle signals on pins 5 and 9. This is definitely not going to work. It's likely that the adaptor is trying to power itself from the select clock on pin 7, and seeing AC or an average DC voltage lower than 3.3V, with insufficient current.

You may be able to rewire your adaptor to swap the Xberry's Pis pin 5 to pin 7, and disconnect the Xberry's Pis pin 7, and that might do it. If not, you need a SNES to megadrive adaptor, if such a thing exists.

If you get stuck but you still really like the SNES controller more than megadrive pads, you could try an 8bitdo wireless M30 SNES controller. I use one of these (the older one that doesn't have the extra analogue sticks, so it exactly resembles the original SNES pad) with the 8bitdo bluetooth adaptor, and like it. You may get more use out of a 6 button 8bitdo megadrive controller though, as you can use all eight buttons and four directions with Next-specific games and with keyjoy mapping in classic speccy games. They sell a 2.4GHz version of this with a controller and adaptor together that most people think has the least lag, or a bluetooth version and bluetooth adaptor sold separately.

It's also worth mentioning that a Next or N-GO has a 74HS157 joystick multiplexer chip between the two joystick sockets and the FPGA, which as well as sharing both sockets between the single set of FPGA GPIO inputs, provides some protection of those GPIO lines. On an Xberry Pi this multiplexer chip is not present, which means any controller you plug in wil register for both sides, but also means pin 7 is connected directly to the FPGA GPIO line. Any third fire button the adaptor might be wired for could also short one of the GPIO lines directly to ground. I would personally not want to risk connecting your wrongly-wired adaptor in its current form, in case you fry the FPGA.

[danboid]

Thanks for your reply Robin!

I was hoping there might've been a setting I could've changed in NextZXOS or in its "BIOS". I don't want to risk breaking it by experimenting with it as I'm not sure I can get another and it works fine with my Amiga. I have ordered a couple of MD controllers which should arrive in the next couple of days. I can't stand using my old 2600 joysticks, I don't know how I put up with them as a kid but I suppose I didn't have any other options and I didn't know any better.

Good to see this forum is still active. I do have a FB accout but I don't think the community should be using it for discussion and support, or at least we should try to minimise the use of social media for productive chats that others may wish to reference but I should be preaching to the choir here. I have made a few posts already to the official specnext forum but none of my posts got a reply after a few weeks.

So why are people still using this but not the official forum? Is it beause the official forum is too captcha heavy? It is a bit tedious having to click the right squares every time you want to post and this forum seems to do OK without all that.

[Seven.FFF]

No problem!

Unfortunately the physical wiring is defined by the soldered connections and components on the board. That's the same for the Xberry Pi, Next ks1, Next ks2 and N-GO. The other side of the interface, how the Z80 sees the controller data through I/O ports or nextregs (kempston/sinclair/cursor/MD/keyjoy protocol), is done entirely in the FPGA, and is configurable by both users and games.

To be fair, nobody goes out of their way to tell you that the Next and clones use megadrive wiring when you buy one. It's not anywhere on the Next website, either kickstarter campaign, the ZX Renew website, the Xberry Pi github, the N-Go website, or in the Next manual or quickstart card. It's documented on the wiki, the distro and everybody's SD card, but you have to dig to find that.

Honestly, I'm not sure that the Next forum is in any way official. It's linked from the Team's website, but was just set up by a community member in the initial days of the first kickstarter, before they abandoned it. It's always been pretty dead, although it did pick up very slightly when the 6,000 new ks2 owners got their machines. The Next Team has always been very much centered around the facebook group from the beginning, and there are about 18,000 users there now. I wouldn't want to speculate too much on why most people prefer social media, as you'd get a different answer from everyone you asked. I think most forums have captchas or other anti-attack measures in place, including Spectrum Computing.

I do try to answer questions on the Next forum and on here, and also in discord, but these are not where the bulk of the main action is happening.

[Nitrowing]

The Next Team has always been very much centered around the facebook group from the beginning

One of the reasons mine has been unloved is that I couldn't see much happening. There's no way anyone could convince me to use social media and definitely never facebook

[danboid]

I recall using Mega Drive controllers on my Amiga and using Atari joysticks on my C64 so I was under the impression that as long as I only wanted one fire button I'd be able to interchange "Atari" style joysticks between these platforms and the Next / XBP but seems that is not so.

I had made a few posts to this forum now and I've not had to solve a captcha once - great! On the other Next forum I have to do a captcha every time I post and I believe that will be putting people off posting there.

[Seven.FFF]

If both ends are only using the lowest common denominator pins 1/2/3/4 for directions, pin 6 for single fire, and pin 8 for ground, then pretty much every computer/console will work with pretty much every stick/pad (apart from Amstrad SJS-1 sticks and Amstrad Spectrum +2/+2A/+3 computers, which have a deiberately incompatible and pathologically consumer-unfriendly wiring).

The problems come with the other pins, as historically every computer/console designer had a different idea about what to use them for. If a stick needs to be powered for autofire or wireless then it needs the computer to supply it on the right pin - either 5 or 7, otherwise the stick is going to act as if it's unpowered or do something weird with a 3.3V AC logic signal on the power pin. If a stick uses a second or third fire then it needs the computer to be using the same pins for it that the stick does. If a stick shorts a power rail to ground because it thinks it's completing a circuit for an extra fire button then the computer is going to reset. If a stick uses one of the pins as an output clock pin then it needs the computer to be outputting a clock on that pin, or else the stick will revert back to 1 or 2 button mode.

A megadrive controller doesn't actually need to be powered at all, so it fits the lowest common denominator quite nicely when it falls back to 2 button mode. That adaptor, on the other hand, does seem to need to be powered, as it's generating the clock signal that would usually be being done by the host computer. I suppose such an adaptor could be designed to work unpowered too, but that seems not to be the case here. It wouldn't beep if it was just passing through the the lowest common denominator pins unpowered.

There's something like 15 different common wirings that all describe themselves as Atari, by which they really mean the lowest common denominator. But most of them are not compatible with each other. There's a lot of confusion about this, and you won't be the first or last to assume that something will work without considering the details.

On both this forum and the Next forum I have to check some kind of captcha box every time my network changes, but not at any other time.

I often see people saying that they only use facebook, and they haven't tried to use a forum for 10 or 15 years. Which is the complete opposite of what Nitrowing thinks. Like I said, it's a personal preference and everyone is different. If you know the action is at one place and deliberately choose to avoid it and only go to the places where it isn't, then that's on you. You get to own your own choices as well as the consequences. It's a form of refusenik just like my mum choosing to only use a typewriter instead of the internet, albeit a less extreme form.