@kdragon_2 RetroPie is just Raspbian Linux underneath, so as long as your setup works with Raspbian and the OS detects your setup as a controller, RetroPie should recognise it and use it. As for the how to communicate with it, that's up to you - Linux/RetroPie already includes a few drivers that interpret GPIO inputs as a controller - look in the Docs.
@europadecas Despite my arcade, electronics, Linux, and coding experience I found Retropie to be a very complex and difficult to manage project. Kudos to the devs for integrating this many emulators into a single environment, and kudos to the support forum here for the help!
I wasn't sure about that line as it looked to do the same thing, however when I pulled the lines from the main retroarch.cfg file, both lines were there so I put them both in "just in case."
Could be that the core looks at one line and retroarch looks at another, or that some lines found else-ware look for the other string.
I commented out the original line and then added a new line above it for backup/troubleshooting purposes so my file like like this at the line :
joypad_autoconfig_dir = "/opt/retropie/configs/megadrive/retroarch-joypads/" # Original line - joypad_autoconfig_dir = "/opt/retropie/configs/all/retroarch-joypads/"
I had to do that for the MegaDrive, Sega 32X, and Sega CD. I don't think you need to make the file three times, probaly just need to make sure the path is correct. However the map file is real small so I made one for each system.
Finally, I re-configured the SNES controller so if I load up anything with the SNES controller, it's mapped out correctly.
Now if I load up either the MegaDrive, 32X, or Sega CD RetroArch uses the controller map for the Sega controller.
I was lucky as the buttons for the D-Pad, A, and B didn't change with the SNES mapping so the Sega controller works the exact same in EmulationStation.
Good luck. If you still need help, just ask and I will try to assist.
There has been some discussion on controller localisation settings for ES where you could choose what help icons you want per your controller but that also has similar issues with mappings/integration with libretro's configs
Yeah, for starters, how about reading this, then provide the details listed. It's hard to give advice when we don't know stuff about your build, which exact emulator you are using and so on and so on. Be specific.