Here's the control layout for the Null 2:
To exit a game, press Start and Select at the same time.
Plugging in headphones doesn't turn off the speakers, so you will need to use the mute switch when you plug them in.
RED means charging.
BLUE means charged.
Charging while the device is turned on is potentially unsafe.
Important: Do not use a high voltage fast charger (like the one the Google Pixel uses) with the Null 2, you will damage the TP4056 module. Check your charger before using it, 5V and 2A should be safe to use.
The button on the bottom acts as a 'system' button.
Holding the system button and pressing the shoulder buttons will change the volume level. Holding the system button and pressing the B button will shut down the Pi so that it can be turned off safely.
System + L = Volume Down
System + R = Volume Up
System + B = Shut Down
This can all be changed if you want it to do something else or maybe remap which buttons control the volume.
The Python script can be found in the /home/pi/Scripts folder.
If using the button for another purpose, you will need to remove all instances of “sudo python /home/pi/Scripts/systembuttons.py &” from the /etc/rc.local file.
When in a game you can use the following shortcuts:
Select + Start = Exit game
Select + Up = Toggle game speed
Select + L = Load save state
Select + R = Write save state
Select + Left/Right = Change save state slot
Select + X = Open RetroArch
These bindings can be changed either through the RetroArch interface:
From the main Null 2 menu, go to System Settings>RetroArch>Settings>Input>Hotkeys. Make your changes and then press B until you're back at RetroArch's main menu. Now go to Configuration File>Save Current Configuration before you quit to keep your changes.
Or you can change the configuration file directly by SSHing in and editing /opt/retropie/configs/all/retroarch.cfg