Installing raspbian without retropie didn't work, even by using video driver which is in overlay folder of boot. So keeping retropie but adding pixel was the solution as retropie can understand that, and can understand that you want to start it instead of buggy emulationstation

I played with frame_width, fame_high for have good screen (not too small) and a little (not too much) with overscan_top/left

the sound have crackling/poping, like have raspis... but It's much better that at the beginning, it was really worse at first...

Now If I want better sound I have to figure out how use an external soundcard and be recognized. Both my ur242 and zoomH4n are not recognized, on the pi boy or on my other raspberry pi, same problem.

Normally I think I can edit config.txt for resolve this, but the config.txt is the same than before (I made a save of the previous one and it seems to be exactly the same and screen width and hight are here so it seems like it don't read config.txt...

emulationstation is in the good format and emulators too, but native application and terminal are bad displayed. This is the configs at the end of config.txt :

# Enable audio (loads snd_bcm2835)
dtparam=audio=on
gpu_mem_256=128
gpu_mem_512=256
gpu_mem_1024=256
overscan_scale=1
# hdmi_force_hotplug=1

# hdmi_group=2

# hdmi_mode=87

# hdmi_cvt=640 480 60 1 0 0 0

# disable_overscan=1

# avoid_warnings=1
dtparam=audio=on
display_rotate=3
dtoverlay=mzdpi6
gpio=18=op,dh,pd
#gpio=0-9=a2
#gpio=12-17=a2
#gpio=20-25=a2
framebuffer_width=480
framebuffer_height=320
enable_dpi_lcd=1
display_default_lcd=1
dpi_group=2
dpi_mode=87
dpi_output_format=0x07f006
hdmi_timings=320 0 28 18 28 480 0 2 2 8 0 0 0 60 0 32000000 1
audio_pwm_mode=1

it's hard because I have to start pi boy, quit emulation station for have the terminal, then plug usb adaptor with ethernet + keyboard, and type commands by hand. I have to figure how connect to ssh on it

So maybe this pi boy 3b+ pi can also do it? I don't know what is the version of my other pi...

But right now my problem is dirty audio in lgpt. I see in other threads that the principal solution was external usb audio interface. But maybe it's outdated because audio works good on my other raspi without usb interface and i would prefer much without

Maybe i should create a new thread for that because it's related to rasppi not specific to pi boy. The audio problem is on a pi3b (which is inside pi boy)

But I finally get it working, (but there is a problem about audio) it seems that it doesn't like when changing stuff on the sd card. I "finished" an important part of my setup, used it like 4/5 times and emulation station always started now. If someone has a pi boy, you must exist lgpt then press start on emulation station then choose system shutdown. If you don't it can corrupt files and don't start again...

And I discover how accessing terminal too. If you choose quit emulation station insead of system shutdown, you arrive to a terminal! And there mapping is easyer because a log is created (have to use mapping event print option with lgpt command in lgpt wiki). You just need to remember which button you press before open the log (with cat lgpt.log for exemple). And doing that I saw that lgpt was good launched from the terminal so if I use only lgpt maybe I will just automatically start it and don't launch emulation station like I did on my standard raspberry pi.

So now it's good mapped and midi works good! BUT, the sound of lgpt is very dirty. It sounds like a problem other people already had here. The thing strange is that sound is fine in other emulation games.

Other points :

- the shoulder buttons behind the pi boy are not good when you put the gameboy on a table because the buttons are pressed, I think it can ruin it in the time, keeping them always pressed...

- screen with lgpt is small, it's fullscreen but lgpt has a yellow part unused around the program, that should be much better to zoom in a bit but I don't know if it's possible. It's a little hard for eyes for me

1) emulation station sometimes don't start but maybe that's because of bad shutdown programs. Normally we need to close emulation station from menu before shutdown the gameboy.

2) for now I can't use buttons correctly, they are crazy mapped from my mapping.xml file (if no file they don't work at all) which is complicated is that I can't see the terminal (or don't know how) and so can't use lgpt key display option. Pi boy doesn't have raspbian only retropie and don't know how access to the terminal from it... With a keyboard connected and using it, it works fine

I added lgpt folder in home/pi. On retropie if I go in options, there is a file manager and I try to launch lgpt from there. It don't work i have black screen I don't know why...

I saw on internet there is the "ports" possibility for non-emulation file by adding file.sh in a specific folder. I have to test that