Adding Genesis/MD to MC-Cthulhu

So, about a year ago I had been working on a plan for a universal arcade stick with support for a bunch of retro consoles plus PC and PS3 (via an MC-Cthulhu board), Sega Genesis / Mega Drive via a padhacked 6-button pad from eBay and Xbox 360 via a leftover control board from one of my Mad Catz sticks.

360 and Cthulhu were supposed to share the same USB-over-RJ45 with a toggle switch to go between them and Genesis/MD was going to have a little pigtail that could hook up to an extension cable when needed. When I got the 360 board wired into the Cthulhu, though, everything went haywire with phantom button presses and all sorts of nonsense. This got me pretty bummed out about the whole project and I put it on ice.

However, there's been a lot of interest over on my MC-Cthulhu pinout page from people trying to integrate Genesis/MD input with the Cthulhu board since then, so I figured I'd better at least finish up that part and report my experience, which I finally did last night.

I won't go into a ton of detail in this post, as the "how" bits have already been covered in my other posts (linked above), so instead I'll focus on what worked and what didn't.

First off, I had originally tried swapping between the Cthulhu and the 360 board (before I abandoned it) using a momentary DPDT switch like you find on a guitar foot pedal. I wanted something tough that was hard to press, so it wouldn't trigger accidentally mid-game. This ended up being the wrong tool for the job, though, as it only switched to the other board while the switch was actually held down. So, I switched over to an ON/ON DPDT 2-position switch. I'm pretty confident this would have worked as intended had my 360 board wanted to cooperate.

The way the switch is supposed to work is: from your USB, you have 4 lines--GND, 5v, Data+ and Data-. The 5v and GND are wired onto the extra solder points on the Cthulhu (that is, the 3 sets of thru-holes where you solder on the RJ45 lines) and the Data+/- lines are wired onto the switch, with 2 coming from the Cthulhu and 2 coming the 360 board's USB header. The output lines from the switch (typically the 2 center leads) connect to the RJ45 lines. In normal use, both boards will be powered (whenever you do a multi-board solution, all boards need their voltage and ground lines connected together at all times) but the one that actually sends/receives data will be controlled by the toggle switch.

Once I got the boards wired together and noticed the strange behavior, I did a lot of troubleshooting and determined that just having the 5v and GND lines linked up was enough to break everything, so that was that. I may revisit it another time with a different 360 board, but for now I decided to just drop 360 support altogether. With the 360 board out of the picture, I didn't need the switch anymore, but I just left it on there anyway rather than having a gaping hole in the side of my stick for dust and liquids to sneak in. Plus, now I have a little fidget thingie I can fiddle with between matches.

sorry for blurry pic :(

Moving on to the Genesis/MD pad, there wasn't really anything unexpected. I soldered the padhack's button lines to the secondary soldering points on the Cthulhu (the 2 rows of thru-holes labeled A-H and 1-9) as outlined at the end of my pinout post and it all works great. The crummy pad I used has a very short cable, which made it super-easy to cram into my already-crowded Mad Catz SE chassis.

Yes, the wiring is a mess. Good thing nobody ever sees it but me (and now you)

You'll notice I did a little loop around a screw post before sending the connector out the back side. That's to prevent the wire from tugging on the pad PCB and ripping out my solder joints. I also covered the entire PCB and solder points with electrical tape to prevent any stray grounding/bridging.

The pigtail. It's pretty unobtrusive without the extension cable attached

You might also notice that I removed the 360 home/LED/turbo panel with a 3D-printed blank, which just barely fits a 24 mm button to serve as the Cthulhu's HOME button.

While I was at it, I took a tip from u/gongfuren on reddit's r/fightsticks board and swapped out some plungers on my short-stem IL competition buttons for a cool "bullseye" look and also removed the springs from the buttons, which gives them a much lighter touch. They're still a lot stiffer than Sanwa buttons (which is good, IMO, as I like to rest my hands on the buttons) but they feel significantly more responsive than with the spring, and they still keep their satisfying cherry click.

Here's the final result:

And here's my other IL stick that I swapped plungers with:

Retro Console RJ45 Pinouts - PS360+, MC-Cthulhu, Brook Retro Board

I build a lot of arcade sticks and I like to use them on old video game consoles, and the best way to do this is usually to get a control board that is compatible with multiple consoles. There have been a few boards that do this over the years, including Toodles' MC-Cthulhu (mostly discontinued but still available sporadically), Akishop Customs' PS360+ (discontinued) and now (at the time of this writing) Brook's Retro Board.

The preferred way to connect these boards to the consoles is via RJ45 connectors soldered to the board and then a console-specific connector soldered onto the other end of the cable. A few arcade parts stores sell premade cables for some of the more popular consoles at the time of this writing, but that will probably stop at some point, so it's good to know how to put these cables together.

There used to be a huge thread with really great tutorials on making these cables on the Shoryuken forums by user "rtdzign" but when SRK migrated to a different forum software a few years ago, it completely fucked up their post index so you can't get to things from google search results and I think the whole forum is shutting down completely soon, so all of this will be lost (most of it already is, really; I had to go sifting through the Wayback Machine's archives to collect most of this stuff).

Anyway, here goes (note: the pics in this post come from rtdzign's original tutorial on SRK and from Akishop Custom's PS360+ manual, with copyrights for those respective images belonging to them):

If you buy a MC-Cthulhu from somewhere, you may want to make sure you have the latest firmware. Toodles' "Godlike Controls" site has been down for a while, but the Wayback Machine cached the firmware file here.
Mirror

The ethernet connection pinout looks like this:

USB

The first cable you'll probably want to make is a regular USB cable (for PC and PS3). It's pretty simple - ground (pin 4 of the USB cable) goes to pin 1 of the ethernet cable, data+ (USB pin 3) goes to pin 5 of the ethernet cable, data- (USB pin 2) goes to ethernet pin 6 and VCC (USB pin 1) goes to ethernet pin 8.

Color - Purpose - RJ45 Pin - Cthulhu - ETH Color
Black - GND     - 1        - G       - Orange Stripe
---   - ---     - 2        - A       - Orange Solid
---   - ---     - 3        - B       - Green Stripe
---   - ---     - 4        - C       - Blue Solid
White - DATA-   - 5        - D       - Blue Stripe
Green - DATA+   - 6        - E       - Green Solid
---   - ---     - 7        - F       - Brown Stripe
Red   - VCC     - 8        - V       - Brown Solid

Original Xbox

Once you've done USB, OG Xbox is a logical next choice, as it's just USB with a proprietary plug:


OG Xbox also has a yellow wire that is unused and can be ignored, but otherwise it's the same as the regular USB cable.

NOTE: in general, don't trust wire colors blindly. *Always* test continuity with a multimeter to confirm wire-to-pin assignment. Cheap, knockoff extension cables are notorious for using essentially random wire colors (including nonsense like red GNDs, black VCCs, etc.)

If your construction skills aren't great and you would rather buy something, I believe you could also just use a USB-female-to-Xbox-male adapter like this one (or build one) and get the same effect pairing it with your newly constructed RJ45-to-USB cable.

Once you've got the hang of it, the rest of the consoles are just a matter of matching up the gamepad pins with the ethernet wires.

Gamecube

Gamecube (not compatible with PS360+) only uses the first 3 pins of the controller, which makes it pretty easy: controller pin 1 is VCC, which goes to ethernet pin 8, controller pin 3 is GND, which goes to ethernet pin 1 and controller pin 2 is DATA, which goes to ethernet pin 7. Easy-peasy.

Here's the diagram:

GC Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1      - +5v     - 8        - V       - Brown Solid
2      - DATA    - 7        - F       - Brown Stripe
3      - Ground  - 1        - G       - Orange Stripe

And the same info in order of RJ45/Cthulhu pins:

GC Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
3      - Ground  - 1        - G       - Orange Stripe
---    - ---     - 2        - A       - Orange Solid
---    - ---     - 3        - B       - Green Stripe
---    - ---     - 4        - C       - Blue Solid
---    - ---     - 5        - D       - Blue Stripe
---    - ---     - 6        - E       - Green Solid
2      - DATA    - 7        - F       - Brown Stripe
1      - +5v     - 8        - V       - Brown Solid

N64

The Brook Retro Board has support for N64, and its pinout is very similar to the Gamecube's but in reverse order. That is, pin 1 is GND, pin 2 is Data and pin 3 is VCC (+3.3v).

N64 Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1       - Ground  - 8        - G       - Orange Stripe
2       - DATA    - 7        - F       - Brown Stripe
3       - +3.3v   - 1        - V       - Brown Solid

And the same info in order of RJ45/Cthulhu pins:

N64 Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1       - Ground  - 1        - G       - Orange Stripe
---     - ---     - 2        - A       - Orange Solid
---     - ---     - 3        - B       - Green Stripe
---     - ---     - 4        - C       - Blue Solid
---     - ---     - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
2       - DATA    - 7        - F       - Brown Stripe
3       - +3.3v   - 8        - V       - Brown Solid

PS1 and PS2

PSX is another good one, since it covers both PS1 and PS2 and was considered the "standard" connector for sticks prior to the adoption of USB, so you can find PSX-to-whatever adapters fairly easily from companies like Raphnet. In fact, Akishop Customs recommends using a PSX cable with a PSX-to-Gamecube adapter to cover Gamecube and Wii inputs with PS360+ boards.

Note: the 'RUMBLE' pin carries 7.2v-9v for use by the rumble motors. We don't need to mess with it.

PSX Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
1         DATA    - 4        - C       - Blue Solid
2         CMD     - 3        - B       - Green Stripe
3         RUMBLE  - ---      - ---    
4         GND     - 1        - G       - Orange Stripe
5         +3.3v   - 8        - V       - Brown Solid
6         ATTN    - 5        - D       - Blue Stripe
7         CLK     - 2        - A       - Orange Solid
8         UNUSED  - ---      - ---
9         ACK     - 7        - F       - Brown Stripe

and here's that same data shuffled around to use the order of the RJ45/Cthulhu pins, in case that is easier to understand:

PSX Pin - Purpose - RJ45 Pin - Cthulhu - ETH Color
4       - GND     - 1        - G       - Orange Stripe
7       - CLK     - 2        - A       - Orange Solid
2       - CMD     - 3        - B       - Green Stripe
1       - DATA    - 4        - C       - Blue Solid
6       - ATTN    - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
9       - ACK     - 7        - F       - Brown Stripe
5       - +3.3v   - 8        - V       - Brown Solid

NES and SNES

SNES / NES is another interesting case insofar as they use the same protocol, just with a different connector. Rather than making/storing/transporting 2 separate ethernet cables, I made one ethernet-to-SNES cable and use a self-made SNES-to-NES adapter for NES (also useful for using the more ergonomic SNES pad on an NES). I also have a cheap SNES-to-Wiimote-expansion adapter (this one from Hyperkin https://www.amazon.com/Hyperkin-Controller-Adapter-Classic-super-nintendo/dp/B075RMYMNH) but neither my PS360+ nor my MC-Cthulhu work with my SNES Classic/Mini through it, so YMMV (worth noting: MC-Cthulhu and PS360+ don't work with my Analogue Super Nt using the normal SNES cable, either, though they both work with an actual SNES console, so clearly something fucky is going on that probably won't ever be resolved for either of the essentially dead products). I haven't tried either of them running through a Wiimote's Bluetooth connection (to, for example, use an arcade stick wirelessly with emulators on a softmodded Wii), so if you try that, please let me know your results in the comments.

To be verbose, here are both the NES and SNES pinouts and pics, respectively (the "unused" pins are reserved for special controllers and serve no purpose for us):

NES

NES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1       - GND     - 1        - G       - Orange Stripe
2       - CLK     - 2        - A       - Orange Solid
3       - LATCH   - 7        - F       - Brown Stripe
4       - DATA    - 4        - C       - Blue Solid
5       - UNUSED  - ---      - ---     - ---
6       - UNUSED  - ---      - ---     - ---
7       - VCC     - 8        - V       - Brown Solid

And here it is sorted by RJ45 pin:

NES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1       - GND     - 1        - G       - Orange Stripe
2       - CLK     - 2        - A       - Orange Solid
5       - UNUSED  - 3        - B       - Green Stripe
4       - DATA    - 4        - C       - Blue Solid
6       - UNUSED  - 5        - D       - Blue Stripe
---     - ---     - 6        - E       - Green Solid
3       - LATCH   - 7        - F       - Brown Stripe
7       - VCC     - 8        - V       - Brown Solid

SNES

SNES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
2        - UNUSED  - ---      - ---     - ---
3        - UNUSED  - ---      - ---     - ---
4        - DATA    - 4        - C       - Blue Solid
5        - LATCH   - 7        - F       - Brown Stripe
6        - CLK     - 2        - A       - Orange Solid
7        - +5v     - 8        - V       - Brown Solid

And sorted by RJ45 pin:

SNES pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
6        - CLK     - 2        - A       - Orange Solid
2        - UNUSED  - 3        - B       - Green Stripe
4        - DATA    - 4        - C       - Blue Solid
3        - UNUSED  - 5        - D       - Blue Stripe
---      - ---     - 6        - E       - Green Solid
5        - LATCH   - 7        - F       - Brown Stripe
7        - +5v     - 8        - V       - Brown Solid

TurboGrafx-16 / PC-Engine

TG16/PCE is kinda weird insofar as it has 2 functions on each pin (e.g. D-pad up and the I button) and then it uses the DATA SELECT pin to select which set of functions to poll.

I don't have a TG16/PCE, but from rtdzign:

The American TurboGrafx-16 uses has a female Din 8 port on the system while the Turbo Duo and all the Japanese systems use a Mini Din 8. I recommend that you buy a number of 6 ft monoprice Mini Din 8 cables. For an TG-16 you can buy a male Din 8 connector and solder that to an ethernet cable.

And here's the diagram sorted by DIN pin:

DIN Pin  - RJ45 pin - Cthulhu - ETH Color
1 +5v    - 8        - V       - Brown Solid
2 UP/I   - 2        - A       - Orange Solid
3 RT/II  - 3        - B       - Green Stripe
4 DN/Sel - 4        - C       - Blue Solid
5 LF/Run - 7        - F       - Brown Stripe
6 SELECT - 6        - E       - Green Solid
7 OE     - 5        - D       - Blue Stripe
8 GND    - 1        - G       - Orange Stripe

And sorted by RJ45 pin:

DIN Pin  - RJ45 pin - Cthulhu - ETH Color
8 GND    - 1        - G       - Orange Stripe
2 UP/I   - 2        - A       - Orange Solid
3 RT/II  - 3        - B       - Green Stripe
4 DN/Sel - 4        - C       - Blue Solid
7 OE     - 5        - D       - Blue Stripe
6 SELECT - 6        - E       - Green Solid
5 LF/Run - 7        - F       - Brown Stripe
1 +5v    - 8        - V       - Brown Solid

Saturn

Saturn pads have voltage lines running in and out of the gamepad. When you see diagrams online, they are typically named according to the console's perspective, rather than the controller's, so keep in mind that these names are basically backward.

Sorted by Saturn pin:

Sat Pin   - RJ45 pin - Cthulhu - ETH Color
1 +5v-OUT - 8        - V       - Brown Solid
2 DATA1   - 3        - B       - Green Stripe
3 DATA0   - 2        - A       - Orange Solid
4 SELECT0 - 5        - D       - Blue Stripe
5 SELECT1 - 6        - E       - Green Solid
6 +5v-IN  - ---      - ---     - ---
7 DATA3   - 7        - F       - Brown Stripe
8 DATA2   - 4        - C       - Blue Solid
9 GND     - 1        - G       - Orange Stripe

Sorted by RJ45 pin:

Sat Pin   - RJ45 pin - Cthulhu - ETH Color
9 GND     - 1        - G       - Orange Stripe
3 DATA0   - 2        - A       - Orange Solid
2 DATA1   - 3        - B       - Green Stripe
8 DATA2   - 4        - C       - Blue Solid
4 SELECT0 - 5        - D       - Blue Stripe
5 SELECT1 - 6        - E       - Green Solid
7 DATA3   - 7        - F       - Brown Stripe
1 +5v-OUT - 8        - V       - Brown Solid

3DO

3DO pads have headphone jacks on them, so 2 of the pins are dedicated to carrying audio signals, and there's a second VCC line. I would assume you can use either of them but haven't tested it, since I don't have a 3DO. Neither did rtdzign, it seems, as here's what he had to say about it:

(I don't have a 3DO and am assuming the D-sub follows normal pinout convention Picture is from a 3rd party genesis extension cable.)

3do will currently only work as the only controller, plugged directly into the system; trying to daisy chain off of it or use it through a daisy chain isn't going to work.

Here's the diagram sorted by Dsub pin:

Dsub Pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
2        - VCC+5v  - 8        - V       - Brown Solid
3        - AUDIO1  - ---      - ---
4        - AUDIO2  - ---      - ---
5        - VCC+5v  - ---      - ---
6        - P/S     - 7        - F       - Brown Stripe
7        - CLOCK   - 2        - A       - Orange Solid
8        - GND     - ---      - ---
9        - DATA    - 4        - C       - Blue Solid

And sorted by RJ45:

Dsub Pin - Purpose - RJ45 pin - Cthulhu - ETH Color
1        - GND     - 1        - G       - Orange Stripe
7        - CLOCK   - 2        - A       - Orange Solid
---      - ---     - 3        - B       - Green Stripe
9        - DATA    - 4        - C       - Blue Solid
---      - ---     - 5        - D       - Blue Stripe
---      - ---     - 6        - E       - Green Solid
6        - P/S     - 7        - F       - Brown Stripe
2        - VCC+5v  - 8        - V       - Brown Solid

Dreamcast

No VMU support and only works with games that can be played solely with an arcade stick. (update 8/4/23): Someone in the comments reported that the original pic was wrong, so here's a corrected pic:

 The diagram was always correct:

Here's the diagram sorted by DC pin:

DC Pin   - RJ45 Pin - Cthulhu - ETH Color
1 DATA1  - 7        - F       - Brown Stripe
2 VCC+5v - 8        - V       - Brown Solid
3 GND    - 1        - G       - Orange Stripe
4 SENSE  - 3        - B       - Green Stripe
5 DATA5  - 4        - C       - Blue Solid

And sorted by RJ45 pin:

DC Pin   - RJ45 Pin - Cthulhu - ETH Color
3 GND    - 1        - G       - Orange Stripe
---      - 2        - A       - Orange Solid
4 SENSE  - 3        - B       - Green Stripe
5 DATA5  - 4        - C       - Blue Solid
---      - 5        - D       - Blue Stripe
---      - 6        - E       - Green Solid
1 DATA1  - 7        - F       - Brown Stripe
2 VCC+5v - 8        - V       - Brown Solid

Sega Genesis / Mega Drive

None of these boards work with Genesis / MD because it does its own crazy thing that's very difficult to reproduce without spending a ton of money on dedicated parts. The best thing to do for these is to padhack a crappy 6-button pad, which can be purchased online for peanuts. See my post here for a look at that process.

MC-Cthulhu Secondary Solder Point Pinout

The Cthulhu boards include a double-row of unlabeled solder points on the side of the board opposite the RJ45 solder points. These are intended for attaching a 360 padhack for adding 360 support, but they're just additional hard-lines tied to the screw-terminals, so they can technically be used to add any additional PCB, so long as you tie the VCC and Grounds together.

Since they're unlabeled, it can be a hassle to use them, but you can easily identify by testing continuity between the solder points and the screw-terms. Nevertheless, I'll include the pinout here to make it easier (the labeling scheme assumes right-alignment; that is, H and 9 are on the far right, lined up, while A and 1 are staggered on the left side):

    [A] [B] [C] [D] [E] [F] [G] [H]
[1] [2] [3] [4] [5] [6] [7] [8] [9]

A = VCC
B = Down
C = Ground
D = Select
E = Right
F = 3K ('Roundhouse' in Street Fighter nomenclature)
G = 3P (Fierce)
H = 1P (Jab)

1 = Up
2 = 4P (PPP)
3 = Left
4 = 4K (KKK)
5 = Start
6 = 2K (Forward)
7 = 1K (Short)
8 = 2P (Strong)
9 = Home/Guide

And, just because I keep needing it and don't feel like searching for it every time, here's a copy of the MC-Cthulhu pinout: