Emulator

Also other then the issues I mentioned, the game runs smooth on both emulators. Dolphin runs at a constant 30fps, and Visual Boy Advance runs at a constant 60.

Please Please, will some one look in to fixing this issue? I am having the same problem and can't play the game with 3 of my friends. I would even donate for fixing the issue.

Hello I'd like to help in correcting this issue. I believe I have an "idea" of what is happening with this but my understanding of this code is very limited.

I'm going to guess that the data transfer is being handled by CSIDevice_GBA::RunBuffer in SI_DeviceGBA.cpp on line 292.

My "idea" is that basically with something like this data is being passed and you have a listener waiting for instruction, or it actively looks for updates on some interval.

If it is the former, this would explain why this issue is occuring. This issue ONLY seems to occur if any player is viewing the radar screen on the GBA.

Now if we think about this for a moment, the Radar screen is the only "view" on the gba that needs to be actively updated from the gamecube side. It is tracking the positional data of your game character on the gamecube in relation to the world map. Every other option screen on the gba is dealing with static information that is only updated as necessary (items for example).

Now, i'm not sure exactly where the conflict lies but I would guess that the "jitter" (which is not actually jitter but held button presses being interpreted as multiple button presses) is happening in the exact same interval that the gba is receiving updates from the gamecube for the map data when using the radar screen.

The other thing is i'm not sure if this happening on the Dolphin side of things, or the vba-m side of things. I don't know exactly how the link cable passes data, or how the gba receives it. But this issue would seem to be something that is happening with GC sending data to the GBA, not the other way around.

I'd be willing to work in tandem with someone who understands the codebase better than I do. Please let me know so we can get in touch!

I have an idea myself. While messing around with the settings on the VGB I noticed after booting my VGB would be running at 200% and reporting 12 FPS and the stuttering would cease. The second that the Gameboy would stabilize and start running at 100% the game would resume stuttering. The only temp fix I can find was as the last guy mentioned stop viewing the radar screen

TarnishedBones wrote:

I have an idea myself. While messing around with the settings on the VGB I noticed after booting my VGB would be running at 200% and reporting 12 FPS and the stuttering would cease. The second that the Gameboy would stabilize and start running at 100% the game would resume stuttering. The only temp fix I can find was as the last guy mentioned stop viewing the radar screen

I am having exactly the same problem. Once the radar screen is turned on the character starts to "jitter".

I agreed with @rookiecookie, the stuttering probably happening because it's treated as press-release-press-release-(so on) instead of continuous presses
Why is this happening? I suspect the game code probably detecting abnormality and attempt to reset the joybus may be (it's been years since i use VBA-M & dolphin, but as i remember i saw reset command FFh in the joybus logs when strange things occurring), or may be the game reset the joybus because it didn't received data within a certain time (in-game timeout)

@TarnishedBones: As i remembered overclocking the GBA to 200% helped reduce the stuttering because it's giving enough time for the GBA to process the data (ie. render the radar tiles), while with normal speed 100% the GBA might not have enough time to fully render it at the time new data is coming from joybus (changing the joybus interval might help but may cause other issue like in-game timeout), when i was playing with the joybus interval i remembered there are cases where i saw the radar tiles didn't get fully rendered and refreshed with new data (where i'm seeing some missing radar tiles near the bottom)

So we need to make sure the GBA-side gamecode is having enough time to fully process joybus data and reply properly to GC before receiving new joybus data, and making sure both side didn't reach the in-game timeout which making them thinking the joybus is having connection issue and attempt to reset it.

PS: if anyone wanted to test different joybus interval value to see the difference, or wanted to see the joybus logs you can use my modified VBA-M (very old version) https://www.ngemu.com/threads/vba-m-svn1030e-support-linking-for-gb-gbc-gba-games.161897/

This is the issue that is blocking me right now and Running the game at 200% is a awful workaround that I can't guarantee I'll always maintain that high of framerate

Is this resolved now since the integrated GBA?