Plunger sensitivity issue on Linux with VP Standalone, resolved

[JamesBarwell]

Hi, I had some trouble getting the plunger working but finally cracked it today. In the ConfigTool on Windows everything worked nicely, and also in Windows joy.cpl. I am using an ADS1115 in a double-ended configuration with a 10k linear pot.

So to be clear, this is not a Pinscape issue. I just wanted to post this to help anyone else who comes across it, and in case it is something you wish to document. It seems similar to #46

When I took the working device to my Linux machine running VPinball Standalone 10.8.0 I found that the plunger would always stick fully up or down, and jitter between these states sometimes when the pot was moved around near its centre position.

I found this issue and comment by francisdb which contains the answer: vpinball/vpinball#1247 (comment)

So there is some weirdness about using axis 3 (Z-axis), which is the default in Pinscape. I don't know where "seems to have a multiplier of 256 defined" comes from but that would certainly explain what I was seeing.

I fixed it by going to gamepad settings in the JSON and changing it so that the plunger was assigned to ry (axis 5) rather than z. My vpinballx.ini config was already set up with PlungerAxis = 5 for my 360 controller so it didn't require any changes.

I only have the potentiometer and haven't built a full plunger assembly yet, as I wanted to be sure it worked! However I can confirm that this is working on both VP Standalone 10.8.0 and in Pinball FX3. I think there may be a mismatch between the sensitivities/travel of the plunger in these two apps which I'll look into once I have it assembled and properly calibrated, but so far so good.

Can't wait to get everything boxed up and working as a proper controller. Thanks for this fantastic project.

[mjrgh]

I'm glad you found a workaround. It would probably be good if someone could get to the bottom of this at some point, since it sounds like there's a clear problem somewhere in there. My guess would be that it's one of the apps getting it wrong, because the numerical ranges that the various axes use are all well-defined - in the case of xinput, they're set in stone by the Microsoft specs, and in the case of gamepad, they're explicitly declared by the device in the HID report descriptors that it sends to the host, which the host is required to respect. The problem could be at either the device driver level (Linux xinput or HID driver), or in one of the applications, but given that it seems that the applications are showing different behavior for the same device, it sounds like it's most likely in one of the applications. If PinballFX3 turns out to be the faulty one, there's probably little hope of getting it fixed since it's a commercial program, but if it traces to VP, that's probably something that can be fixed.

[winxi01]

I fixed it by going to gamepad settings in the JSON and changing it so that the plunger was assigned to ry (axis 5) rather than z. My vpinballx.ini config was already set up with PlungerAxis = 5 for my 360 controller so it didn't require any changes.

Thanks for posting this here. With this workaround, I finally got my plunger to work with VP Standalone 10.8.0.

As a side note, this specific plunger issue seems to be fixed in the latest master of VP 10.8.1 (have tried it with commit d59b54c and different input mappings for the plunger position). Additionally, VP 10.8.1 lets you configure the input mapping for the plunger speed in the in-game menu (I'm not sure if the corresponding functionality is already properly implemented but at least it lets you configure it and I don't think that this is possible with Standalone 10.8.0).
However, at the moment VP 10.8.1 is still quite experimental and unstable, so it's good to have the workaround from above to make the plunger work with the more stable VP Standalone 10.8.0 under Linux.