@mitu
i have 2 usb to the Pi
1st wireless keyboard+mouse
2nd bluetooth dongle

reason you're not using the built-in Bluetooth of the Pi 3B+
already try with built in bluetooth
I got the same problem sir

@mitu IT WORKED!!!!!

I needed to install xpadneo. Thank you so very very much - I spent so long trying all the different combinations!!

@mitu I'm not sure how to describe it. I've tried 3 different versions of Ubuntu and Pop OS and they all do the same thing after installing RetroPie. It will crash once when starting for the first time then work fine. The 8bitdo buttons don't program correctly the first time but will all map the second time. Then after I run a rom it stops recognizing the 8bitdo or it won't even load the rom and just locks up the system. The bluetooth stops responding on the OS desktop as well. I'll try to look into the 8bitdo firmware and see if that is an issue. I'm at a loss at this point.

@pmdci

One thing that Iv'e read should improve (some)things is editing this file,

sudo nano /etc/systemd/system/bluetooth.target.wants/bluetooth.service

look for a line like the following and make it like below.
(maybe make a backup copy of the file first if you want)

ExecStart=/usr/lib/bluetooth/bluetoothd --noplugin=sap

Iv'e been messing around with RPi4 bluetooth and my DS4 controllers recently and that is now part of my setup steps.

@mitu

Pi Model or other hardware: RPi 4 B+
Power Supply used: (If using a Pi)
RetroPie Version Used 4.6.6 version
USB Devices connected: none
Controller used: ps4 replica

sorry I'm late with this. Could this bluetooth connection problem be connected to the recent hack?

@mitu Well as I said, the Bluetooth functionality was working perfectly when setting up the 8bitdo controller and problems only began when the Pi was restarted. As regards the SD card, it's a 32GB card, branded 'Team' and was bought from a local computer store. To be honest, I've had my doubts about it, so I think I'm going to purchase a 32GB Sandisk Ultra card to replace it. I have also since sourced the official Raspberry Pi 5.1v 2.5A PSU to replace the one sent with my ABOX kit. So between the two new pieces of kit, I'll set up Retropie afresh and see how it goes.

Thanks for your patience and help with this issue, it's appreciated.

Please give more details about your system - https://retropie.org.uk/forum/topic/3/read-this-first.

Bluetooth connection can induce lag, but I suggest you test first with a wired controller (I think the SFC30 has this option) to see if it's the lag disappears or if there are other factors that add lag. Make sure your TV is set to Game Mode - if that's what you're using.

One method to improve the Bluetooth connection - and reduce the input lag - is to get an external BT USB adapter and disable the onboard BT or to disable the Wifi on the Pi. The 3B+ model has a better wireless chip (BT and WiFi), but since you didn't provide any info about your device, it's hard to determine what's the status on that.

Well, first you have a lot of addons installed that might be related to "piracy", I don't care about it, but that might cause problems, especially because many of them are done by people with little experience in coding and/or with malicious intents, be carefull about what you add to Kodi.
Second, you have a lot of errors (besides the ones from the addons I mentioned above) that Kodi cannot read or says that the file is read only:

1:43:30.972 T:1631396784 ERROR: SQL: [Textures13.db] Attempt to write a readonly database

This generally indicates that your system suffered file corruption, or most likely, your microSD card is broken or faulty.
This isn't easy to fix, and is impossible if your card is broken.
Try to move or delete your Kodi settings (/home/pi/.kodi) to start fresh with default settings.

@mitu alright so after updating everything from source and powering down and coming back I got the it to pair with my switch pro controller which seems to work fine now. I also turned off Bluetooth on all my other devices in the house phone smartwatch etc maybe that helped

Still having issues with the SteelSeries. Able to configure and regsiter all the buttons in device setup. In emulation station all the buttons seem to work as programmed but once a rom is launched the center buttons the ones I have programed to start and select don't register. Looking through the forums it seems will have to jump through a lot of hoops to get the device to play nice with the SteelSeries XL.

Any suggestions?

Btw thanks again!!!

Apologies I've remedied the issue now by updating Retropie :)

Out of interest how do I set the Bluetooth Snes pad to player 2 and my wired Buffalo pad to player 1? Many thanks

i see that controller has an integrated 3-way mode switch, have you tried booting retropie with it in each of the 3 modes? have a look at this guide:

https://github.com/RetroPie/RetroPie-Setup/wiki/Universal-Controller-Calibration-&-Mapping-Using-xboxdrv

it might be the next step if nothing else works. also, this thread is old but may still be of help: https://forum.xda-developers.com/mad-catz-mojo/general/setting-c-t-r-l-r-retroarch-t2987569

@itsnitro I just have to save those four folders and when I get setup again they can be put back on SD card

Formated the microSD card, wrote the latest img file (4.2) and now all is good.
Controllers are now installed and working fine.
Case closed. Thanks.

I tried to remove the USB dongle for the mouse/keyboard today, and it resulted in a lot longer playing time before freeze. This freeze issue is definitely related to controller hookup!

I have had a weird experience 2 times... i let the frozen screen hang, and after a good while, the game resumes ?!?! Well, the controller connection is lost, even though the controller LEDs are still lit. If i turn off the controllers and turnthem back on again, they won't pair wih bluetooth.

But it means that i can maybe pull some log files - I'm just not experienced enough to know which logfile woud be relevant, and how to pull it. Maybe someone could help me out in this regard??

@NYIslanders91 Please do not post a support request without first reading and following the advice in https://retropie.org.uk/forum/topic/3/read-this-first

It's fun to see how well this community works together and like to help each other.