NOTE: I am using the dual joystick version of xarcade, not the tank (with the trackball).
I have been wrestling with a similar issue for the last couple of weeks. I was using a converted original xbox before I got my pi, and I tried to use the xbox adapter on the pi (the xbox adapter has both xbox style connectors coming out of it as well as usb connectors, both for connecting to your emulator machine).
In a nutshell, the pi would *not* recognize the xarcade using the xbox adapter, and I suspect you will have the same issue. I bought my xarcade over the summer, so it has the PS/2 connector and the 9-din connector. I swapped out the xbox adapter for the 9-din – to – usb cord that was also provided with my purchase, and the retropie, upon reboot, immediately recognized the dual joystick as a gamepad. I also enabled the xarcade2joystick service in retropie, and I was finally able to configue the device.
This may be what you have to do. If not, great, but this may save you a *lot* of time and confusion (and in my case, a near aneurysm from frustration).
The old X-Arcade sticks with only the serial/PS2 adapters do work with the PS2 to USB adapter, *HOWEVER* you have to have a PS2 keyboard plugged into it (then it plugged into the adapter) for it to function… You also have the option of buying an upgrade kit for your stick (which is what I did on my first gen SOLO stick):
I went the DIY route with my X Arcade stick. I bought the parts, so the case, joysticks and buttonns from the X Arcade website. So no electronics. I gutted two wired xbox360 controllers and use those in place of the official X Arcade board.
^^ my other hobby