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I recently bought a RetroBit 6-button control pad with the intent of taking it apart and retrofitting the innards to a 6-button arcade stick I have.

My goal is to have the stick work with bluetooth or while physically connected. Because the Bluetooth controller has a "home" button for pairing, I was going to map that to the never used "Mode" button on the Arcade stick.

What I'm wondering is if my logic is correct with wiring. I was planning on placing a common ground wire between the boards (dont know where yet) and then using the probe pads to connect "A" to "A", "B" to "B", etc... does that make sense? Would it work? Any suggestions?

Below are some images of the boards as well as when I plan to do.
(I didnt fully dissect the Up/Down/Left/Right of the arcades stick so I just put a red blob around the pads (I'll figure it out later).

20200619_103741.jpg (1.41 MB)

20200619_100633.jpg (3.18 MB)

Concept.jpg (205.13 KB)

Yep, those both look like common ground boards, so you should be good. You might want to use a pair of diodes per input, to make sure the boards don't somehow short each other out (I had this issue with a Neo Geo and a JPAC). Remember, it's common ground, so make sure you get the diodes the right way, if you need them.

If you use stripboard, you can do what I did for my arcade cab's kick harness, which is set up a kinda bus type thing, with all the inputs hooked up to every other rail, and then use diodes to jump to the adjacent rail where you connect the outputs. It's a repeating 2x3 pattern. Then you can always hook up EVEN MORE PCBs if you want, and it's just one cut/drill on the rail and three solder joins per input.

BTW, if you ever wanted to take it a step further, you might be interested to know that Saturn pads use the same 9 lines that the MD uses, just with a different connector and logic, so you could add a RetroBit Saturn PCB and add a DE-9 connector to the pad-end of the cable, add a switch to control power to the MD and Saturn PCB, and then hook both boards up to the MD cable (I'm almost certain you'd need diodes here, and be aware that TH is used to control the multiplexer on both pads, and TR is also hooked up to the multiplexer on the Saturn pad) and use the Saturn pad cable as a DE-9->Saturn adapter. Just hook the outputs up as Sik describes for the "keyboard adapter": https://www.arkagis.com/controls

Edit: It just occurred to me that if you're planning to use the original chassis, you'll probably want to just connect the two pads together and hope that they don't short each other out. If they do, you can try adding a single set of diodes for every PCB that isn't the MD board, and if that still has issues you'd need to cut the traces on any problem buttons on the MD pad between the test pads and the ICs so that you can add a diode in there. In fact, if you have any shorts, you probably ought to cut all the traces to add diodes, it'd be faster than testing the 256 possible button combos + a full circle.

Sik also built a controller diagnostic function into the trial version of Arkagis, which is available from the above link. Just mash reset three times to get to it. Try as many combos as you can when testing, because you may find one that causes false positive inputs. Do the same with the controller properties window on Windows. That's how you'll know whether you need diodes or not.

Thank you for the reply. TONS of information. I'll let you all know how it goes

Happy to help! I've just realized some of it will probably not apply, since you've probably got limited space in the chassis, but it's always nice to have options. That said, if space was an issue but you wanted to add Saturn support, it's very easy to build a small controller board for the Saturn using the schematic on http://www.gamesx.com and a small piece of stripboard. The note on the schematic mentions two pins that may need to be pulled low for detection, I can confirm that those pins in fact DO need to pulled to ground (it's right there in the SMPC manual, so I'm not sure why there was ever any doubt).

Author	Message
Tha_Ape Joined: 22 Feb 2020 Posts: 51 Location: Washington, DC	Dual Use BlueTooth/9-pin 6-button Arcade Stick (CONCEPT CHECK) Posted: Sun Jun 21, 2020 1:25 pm
	I recently bought a RetroBit 6-button control pad with the intent of taking it apart and retrofitting the innards to a 6-button arcade stick I have. My goal is to have the stick work with bluetooth or while physically connected. Because the Bluetooth controller has a "home" button for pairing, I was going to map that to the never used "Mode" button on the Arcade stick. What I'm wondering is if my logic is correct with wiring. I was planning on placing a common ground wire between the boards (dont know where yet) and then using the probe pads to connect "A" to "A", "B" to "B", etc... does that make sense? Would it work? Any suggestions? Below are some images of the boards as well as when I plan to do. (I didnt fully dissect the Up/Down/Left/Right of the arcades stick so I just put a red blob around the pads (I'll figure it out later). 20200619_103741.jpg (1.41 MB) 20200619_100633.jpg (3.18 MB) Concept.jpg (205.13 KB)

Wafer Joined: 22 Sep 2019 Posts: 98	Posted: Sun Jun 21, 2020 1:47 pm
Wafer Joined: 22 Sep 2019 Posts: 98	Yep, those both look like common ground boards, so you should be good. You might want to use a pair of diodes per input, to make sure the boards don't somehow short each other out (I had this issue with a Neo Geo and a JPAC). Remember, it's common ground, so make sure you get the diodes the right way, if you need them. If you use stripboard, you can do what I did for my arcade cab's kick harness, which is set up a kinda bus type thing, with all the inputs hooked up to every other rail, and then use diodes to jump to the adjacent rail where you connect the outputs. It's a repeating 2x3 pattern. Then you can always hook up EVEN MORE PCBs if you want, and it's just one cut/drill on the rail and three solder joins per input. BTW, if you ever wanted to take it a step further, you might be interested to know that Saturn pads use the same 9 lines that the MD uses, just with a different connector and logic, so you could add a RetroBit Saturn PCB and add a DE-9 connector to the pad-end of the cable, add a switch to control power to the MD and Saturn PCB, and then hook both boards up to the MD cable (I'm almost certain you'd need diodes here, and be aware that TH is used to control the multiplexer on both pads, and TR is also hooked up to the multiplexer on the Saturn pad) and use the Saturn pad cable as a DE-9->Saturn adapter. Just hook the outputs up as Sik describes for the "keyboard adapter": https://www.arkagis.com/controls Edit: It just occurred to me that if you're planning to use the original chassis, you'll probably want to just connect the two pads together and hope that they don't short each other out. If they do, you can try adding a single set of diodes for every PCB that isn't the MD board, and if that still has issues you'd need to cut the traces on any problem buttons on the MD pad between the test pads and the ICs so that you can add a diode in there. In fact, if you have any shorts, you probably ought to cut all the traces to add diodes, it'd be faster than testing the 256 possible button combos + a full circle. Sik also built a controller diagnostic function into the trial version of Arkagis, which is available from the above link. Just mash reset three times to get to it. Try as many combos as you can when testing, because you may find one that causes false positive inputs. Do the same with the controller properties window on Windows. That's how you'll know whether you need diodes or not.

Tha_Ape Joined: 22 Feb 2020 Posts: 51 Location: Washington, DC	Posted: Mon Jun 22, 2020 11:28 am
	Thank you for the reply. TONS of information. I'll let you all know how it goes

Wafer Joined: 22 Sep 2019 Posts: 98	Posted: Mon Jun 22, 2020 12:24 pm
Wafer Joined: 22 Sep 2019 Posts: 98	Happy to help! I've just realized some of it will probably not apply, since you've probably got limited space in the chassis, but it's always nice to have options. That said, if space was an issue but you wanted to add Saturn support, it's very easy to build a small controller board for the Saturn using the schematic on http://www.gamesx.com and a small piece of stripboard. The note on the schematic mentions two pins that may need to be pulled low for detection, I can confirm that those pins in fact DO need to pulled to ground (it's right there in the SMPC manual, so I'm not sure why there was ever any doubt).

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