GRS Spinner sensitivity problems in MAME

[Teh Lurv]

Hey everyone; long time lurker, first time poster.

For a winter project I've been converting my old A1U cabinet into a general purpose MAME cabinet with a spare Pi 3B and RetroPie. I'm at the point where I'm tweaking MAME settings for the various games when I hit a snag with Tempest.

I'm using a GRS Spinner V2 and I've been following the formula described in this thread:
http://forum.arcadecontrols.com/index.php/topic,164017.0.html

Setting the GRS pulses to 1024/512 and adjusting the analog sensitivity accordingly to the formula results in the blaster moving much slower than it should (free spinning the knob as hard as I can barely gets the blaster one full rotation on level 1). The blaster does move five spaces per 1 full turn. I can increase the sensitivity until the blaster is moving at a familiar speed, but doing a full turn has it moving across a dozen spaces.

Oddly, setting the GRS spinner to 64 pulses and following the formula does result in the blaster behaving as it should. The problem now is the spinner pulses are now too low for games like Major Havoc.

I'm not sure if this is an issue with the spinner, MAME 0.78, or that I'm using a Pi platform. Has anyone run into this issue with the GRS spinner?

[KenToad]

I have no idea about that specific hardware/software setup. Have you tried hooking up the spinner to more recent versions of Mame on better hardware? If you're set on this specific combination of things, there are probably Facebook groups that might have more experience. Good luck!

[DarthMarino]

Out of the box, the GRS spinner works great with Windows/MAME when calculating based on a resolution of 720. I'm not sure how a Pi and RetroArch would effect the resolution. You can try checking on a website like this but it's not terribly intuitive.

https://www.mouse-sensitivity.com/dpianalyzer/

[bollwerk]

I'm not sure if this is helpful, but I adjust the sensitivity in MAME for each game individually, and the settings are saved per-game. I have a TurboTwist2 spinner. Note that I'm not adjusting anything on the spinner itself. If I understand your post, it sounds like you're adjusting something directly tied to the spinner hardware (perhaps in addition to adjusting MAME settings?).

I used the same forum thread as a starting baseline for each game, but tweaked further on some games to personal preference.

[Teh Lurv]

Thanks for the replies, I wanted to provide an update on my issue. I dug a little more into my problem and came across information about mouse polling in Linux: https://wiki.archlinux.org/title/Mouse_polling_rate#Polling_rate_and_polling_interval

I added usbhid.mousepoll to the boot config file, set the GRS spinner to pulse at 512, and did some testing. Without that command or when I set it to value 0 (system use polling rate requested by device), my spinner runs slow. When I force the system to poll at either 1, 2, 4, or 8, the spinner runs at a much faster speed. The spinner moved at the same speed with all four values, so I left it on 8 to save CPU cycles on the Pi.

I set MAME sensitivity according to the formula (14%) and the blaster now free spins at the familiar speed. I can also properly adjust Major Havoc. Interestingly when I do a 5-space full turn test, a full turn with the GRS is exactly 10 spaces. The blaster isn't moving twice as fast; the blaster clicks at the same speed as this guy's setup with a turbotwist: https://youtu.be/0_aIkkObZWM?t=130 I wonder if the GRS is reporting a half turn as a full turn.

In any case, I'm willing to call this issue resolved to my satisfaction.