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Joystick Initialization in Linux

A topic by N[]NE created Dec 26, 2016 Views: 958 Replies: 12
Viewing posts 1 to 6
(Edited 2 times)

The first time I start FPV Freerider with a transmitter I have just plugged in, everything is off center. Then if I close out and restart, everything centers perfectly. This happens with both of my transmitters. It only happens in the Linux version of FPV Freerider and Recharged.


Thanks for reporting. That's a weird thing, I will keep it in mind in case I manage to find out what might be the cause.


To support this, I've also had this anomaly happen in Debian. Have not thoroughly tested the order of operations to find a cause, as the reload generally works.

Same here. Would be nice to know what library the game is using to manage the joystick. Evdev? SDL?

Been thinking about this for a few days as I notice that when I set calibration via /dev/input/js0, the calibration and the mappings are not observed in FPVF.

Developer (Edited 2 times)

Seems like a pretty common problem on Linux. I use Unity for development and basically just have to hope that it works on the different Linux distributions (I'm not a Linux user myself). I tried to search around for more info on this issue but I couldn't really find much. Hopefully some Linux guru will be able to chime in.

Here's one thing a found:

"Had the same issue on two other Unity-games. There is a simple workaround that worked for those games and might work [..]

- You need to callibrate (move the analogs around) before starting the game.

Just do a couple of circles with the analog sticks before starting the game and it should be fine.
As i understand it it's a bug with Unity's controller library under Linux.

Thanks. I'll look into what Unity is using (probably SDL). Just thought it was odd that I couldn't actually SEE the data stream anywhere I'd normally look. I figured it had to be evdev, but nada.


Ok, it will be interesting to hear if you manage to figure something out.

(Edited 1 time)

Moving the sticks around doesn't do anything unless an application is "looking at" them. Either FPV Freerider or jstest-gtk needs to be running in order to recenter the sticks. This is what I have been doing. Move the sticks around and then close and (re)start FPV Freerider.

If I run jstest-gtk first and move the sticks around, then run FPV Freerider, it initializes just fine, but that isn't really a true fix. As long as something initializes the transmitter before running Freerider it works just fine.


I have just install FPV freerider however on a fresh Ubuntu 17.04 instal, my transmitter is not working, no signal seemed to be detected.
The transmitter works well: FPV freerider has no issue with it when I tested on Windows; It appears as expected in /dev/input/js0 and also creates an entry in /dev/input/by-id/usb-xxx-event-if00; jstest-gtk works great; Velocidrone is recongnising the transmitter correctly(on the same ubuntu install).
The log only says:
Desktop is 1920 x 1080 @ 60 Hz
Using libudev for joystick management
Importing game controller configs
UnloadTime: 1.813000 ms

Any ideas on where the issue could be or how do I get debug information?

After some research, as someone mentioned, some buttons must be emulated otherwise the controller is not recognised by FPVfreerider.

To do that, use the wejoy : https://github.com/Vantskruv/w... and calibrate the original joystick with jscal to get rid of deadzone. Then FPVfreerider is working like a charm!


Thanks for reporting back. I'm glad you found the solution, I'm sure it will be of help to others!

Anybody with wejoy  config file? I got working just 2 axes.