Can't enter ppsspp menu

[starfox1986]

I successfully got my psp Roms working on my Recalbox 8 / RPI 3B. However I did not find any information how to open the ppsspps config menu while ingame.
Some sources said I need to plug in a keyboard and press Esc. That doesn't work. Others say I need to map a certain key to my controller (I use Dualshock PS3 Controller) but I don't know which one to name in the mapping ini of ppsspp.

Anyone can tell me how to open that menu? Thank you very much.

[Zing]

@starfox1986

Anyone can tell me how to open that menu?

Have you ever tried Hotkey+B?