@obsidianspider
you may have some issues in connecting and configuring the buttons of your bluetooth controllers. But once it's done, it's really easy to switch between the available controllers in RetroArch.

Trying to ask your question "how does the system choose which controller to use?" (assuming system = RetroArch). Like I said in my first response, RetroArch define some indexes for the controllers. The default is player1 = index 0, player2 = index 1, and so on (I didn't make it clear in my first post). But you can change it in retroarch.cfg. What the RetroPie-Setup config editor and my joystick-selection tool do is just this: change these options in retroarch.cfg.

BTW: the options related to what we are talking about here are input_player1_joypad_index, input_player2_joypad_index, etc...

I managed to get it to work!

Turns out that I had to change the retroarch.cfg files inside the individual emulator folder, since the global retroarch.cfg file changes did not seem to register for the Neogeo ROM :)

@bidinou said in Recommended way to configure GPIO buttons-to-commands:

HI ! Really sorry for hijacking this thread with my own question but I never managed to get an answer :)

Why are you hijacking? I don't mind adding additional content to this, but if you already asked this question somewhere, why didn't you continue the conversation with whomever responded?

Hi, thanks @BuZz - all seems to work now. I got a few errors flash past as it was building but nothing that has stopped it from working. Hope it fixes it for you too @simonster.

I did have to play about with the retroarch.cfg file in the /nes folder to get it to work with my NES controller, but fixed it by setting the player 1 control to:
b_btn = "1"
select_btn = "2"
start_btn = "3"
up_axis = "-1"
down_axis = "+1"
left_axis = "-0"
right_axis = "+0"
a_btn = "0"

All the rest to "nul". If I didn't do this then as soon as I started a nes game it would not respond - I'm sure there is a proper config, but I spent a few hours playing about with the config files before I got it working so now enjoying some sweet retro gaming :)