Razer Raion padhack

One of the problems when making a custom fightstick (arcade controller for fighting games) is modern console compatibility. While it was easy to make an Arduino or similar board work as a USB controller for the PS3, unfortunately it is no longer the case with the PS4 and PS5. Only licensed controllers work with them due to restrictions introduced by Sony. Every licensed controller has a private key embedded in it that allows it to perform some kind of authentication when connected to a console. One solution to this problem is a practice known as padhacking: taking the insides of an existing licensed controller and transplanting them into a different enclosure, for example a fightstick-shaped one, carefully soldering wires between buttons and the right places on the donor PCB.

In theory you can use any controller for this, like a DualShock 4 or a DualSense, but it makes sense to choose one that will be relatively cheap to obtain and also easy to solder to. One such controller is the Razer Raion. It was originally released for the PS4, but since it qualifies as a "specialty peripheral", it also works in PS5 games. I got one and made a mixbox-layout fightstick using its PCB.

First I had to figure out where the solder points that I need are on the PCB. Fortunately I found this helpful tweet and with this information it was a fairly straightforward job.

The rest of the fightstick was similar to what I've done previously, in fact I just modified one of the designs to accomodate the Raion PCB. Here's what it looks like inside. As you can see it uses common ground.

One thing to keep in mind when converting a controller like this is the matter of SOCD cleaning - what happens when you press opposing direction buttons at the same time? Most traditional controllers don't have to worry about this because it's physically impossible to simultanously trigger opposing directions on them. But when you make a stick that has separate buttons for up, down, left and right, that can be pressed independently, it's something you have to start thinking about. In case of the Razer Raion, it uses a scheme called first input priority, meaning that if you press and hold left, then press and hold right, it will keep sending left. When you release left, then it will start sending right. If I didn't like this, I'd have to add an external SOCD cleaner between the buttons and the Raion PCB.

I posted the 3D-printable models for this stick on Printables. It uses Kailh low profile (choc v1) mechanical keyboard switches for the buttons. Here's what the final result looks like.