Logitech trackball mouse TM-150r can be wheeled on Ubuntu 20.04

Introduction

I love Logitech's trackball mouse TM-150r. Even on Ubuntu 20.04, I wanted to add a wheel function to TM-150r, and I did a lot of research, so I will leave it as a memo. Specifically, I made it possible to scroll by moving the cursor while pressing the small button (left small button) above the left mouse button.

Preliminary research

First, I checked the id of TM-150r with the following command.

$ xinput list

Then

↳ Logitech USB Trackball                  	id=11	[slave  pointer  (2)]

I found out that the id of TM-150-r is 11.

Then I typed the following command to identify the number of the small left button.

First, without pressing anything with the mouse

$ xinput query-state 11

11 is the id you identified earlier. Then the output is

2 classes :
ButtonClass
	button[1]=up
	button[2]=up
	button[3]=up
	button[4]=up
	button[5]=up
	button[6]=up
	button[7]=up
	button[8]=up
	button[9]=up
ValuatorClass Mode=Relative Proximity=In
	valuator[0]=2427
	valuator[1]=902
	valuator[2]=119
	valuator[3]=833

I think it will look like this. All are up. Next, execute `` `xinput query-state 11``` while holding down the specified left small button

ButtonClass
	button[1]=up
	button[2]=up
	button[3]=up
	button[4]=up
	button[5]=up
	button[6]=up
	button[7]=up
	button[8]=down
	button[9]=up

And since 8 is down, I know that the number of the left small button is 8.

Rewriting Ubuntu settings

Now that you have identified the button, rewrite /etc/X11/xorg.conf. In my case, xorg.conf was not published, so I created xorg.conf with the touch command. After creating it, just rewrite it as follows with the vi command.

Section "InputClass"
        Identifier      "Marble Mouse"
        MatchProduct    "Logitech USB Trackball"
        Driver          "libinput"
        Option          "ScrollMethod" "button"
        Option          "ScrollButton" "8"
        Option          "MiddleEmulation" "on"
EndSection

This 8 is the number of the left small button that I checked in the preliminary survey. Finally, when reboot is done, the setting is completed. If you want to make it a small right button, you can specify the button number and set it by the same procedure.