Have you tried your hotkey and fire at the same time, usually its select/coin and one of your buttons for various commands
I'm not sure what a hotkey has to do with this. I can hook up a PS4 Controller (If I hit the PS4 logo button + the start button it will exit out of mame as a hotkey etc..) I can program / assign / map my Keyboard using the TAB key in MAME recognizes those as inputs. With retroarch being in place it takes over the controls in MAME & just won't see the zero usb encoders when trying to map them in MAME using the TAB / enter input key. Again the various components don't like each other that I'm trying to have work are:
Raspberry Pi 3b+
MAME 2003 Libretro
MAME Set .78
Retro Arch
Zero Delay USB encoders
If I replace MAME 2003 libretro with say Advance Mame 1.4 etc I don't have the issues of being able to map the buttons within the TAB feature of MAME (Advance mame), therefor I know the zero delay USB encoders work just fine. but I know .78 in conjunction with libretro 2003 has the best collective compatibility with games running on the rpi3b+ . When I switch the emulators that MAME uses from libretro 2003 to advance mame, within MAME if I hit the TAB key it works as it should & I can map the buttons. I think my main issues are with the fact that MAME Emulator libretro 2003 is using RETROARCH, that's where I'm having difficulties. I would imagine you can within a .cfg file turn off RETROARCH all together ? My next step is to just order an IPAC4 where I think it would work being it's proabably going to be recognized as a keyboard encoder instead, but I really don't want to run into the same issues that and purchasing 4x zero delay encoders are half the price and in theory for my purposes if I can get the zero USB encoders working would be a much more suitable / economical.
This is exactly my issue right from GitHub's site but I don't understand how to fix it:
To access the MAME internal menu, press the 'TAB' key or R2.
Whilst lr-mame2003 is a libretro emulator and benefits from automatic controller configuration, sometimes you may still want to rebind how it internally deals with inputs. For example, the default control setup might make sense in one game, but in another they don't. In which case, you can use the 'Input (this game)' option to rebind keys for a single game, generating a .cfg file in:
/home/pi/RetroPie/roms/mame-libretro/mame2003/cfg/
or, if you're using the arcade folder:
/home/pi/RetroPie/roms/arcade/mame2003/cfg/
If you rebind global inputs ('Input (general)'), it will update a file in the same directory called default.cfg.
These files are not human-readable, but can be safely deleted if you get into a mess and wish to return to the default configuration.
Also states this on the GitHub site:
Controls
lr-mame2003 utilities RetroArch control configurations. Add custom retroarch controls to the retroarch.cfg file in:
/opt/retropie/configs/mame-libretro/retroarch.cfg
Being that I'm setting up a 4-Player Cabinet using 4x zero delay usb encoders it would really be ideal If i can just get into the MAME hit the TAB as usually and just hit ENTER on each corresponding inputs... Sadly that doesn't seem to do anything when using these usb encoders.