If there is a lot of delay between touching the screen and the action you selected, or multiple touches generate just one action, activate the function Touch Sig Workaround under the Touch in Settings -> User interface.

Had to look to the firmware. Copilot saves some time, but always check for AI slop:

"Touch Sig Workaround" is a firmware setting related to the touchscreen on Prusa 3D printers (specifically models using the GT911 touchscreen controller).

What does it do?

• It changes how the firmware processes touch events from the hardware.
• Normally, the touchscreen signals a touch event using a hardware interrupt signal ("touch sig"). However, in some scenarios (possibly due to electrical noise or hardware quirks), this signal may not be detected reliably.- When "Touch Sig Workaround" is enabled, the firmware ignores the requirement for the hardware interrupt and instead polls (checks) for touch data directly. This allows the touchscreen to function even if the signal is missed.

How does it work in code?

• In `Touchscreen_GT911::update_impl`, if the workaround is enabled (`config_store().touch_sig_workaround.get()`), the firmware will process touch events even if the hardware signal ("touch sig") isn't detected.
• If the workaround is off, the firmware only updates the touch state when the hardware signal is detected.

Why is it needed?

• This workaround helps prevent "ghost touches" or missed touches caused by electromagnetic interference or other hardware issues.
• It improves touchscreen reliability on affected devices by ensuring touch events are not missed due to signal problems.

Summary:

"Touch Sig Workaround" is a reliability feature for the touchscreen. When enabled, it allows the firmware to detect and process touch events even if the usual hardware signal is missing, helping avoid missed or false touches.

So, according to Copilot:

• When off (default): Firmware fires touch events reactively on hardware interrupts.
• When on (workaround): Firmware reads GPIO pin touch signal value for during each cycle of main event loop. Presumably resolves issues with interrupt signal not firing properly for some users.

I only found one relevant function referencing the setting in sources: touchscreen_gt911.cpp:231. It seems clear that the actual touch events are only being handled when the flag is off, and I get the impression this handler always to be called from the main thread event loop. Another helpful comment further down to support (source):

// Report that the touch sig workaround is on and we've detected a touch data without the interrupt

Someone more familiar would have to confirm. My guess is it was not included in release notes or documentation simply because it is obscure.

https://help.prusa3d.com/article/touch-screen-mk4-mk3-9-mk3-5-xl_689554

Teamwork,

Steve

Posted by: @oregun

Awesome! Ordered the mmu3 for my mark4! ThanJks!!

My question is what is the menu item just below: "Touch Sig Workaround" ? 

From 6.0.0 release notes: "Tip: If you experience issues with the touch, please enable the Touch Sig Workaround option in the menu. Navigate to Settings -> User Interface -> Touch Sig Workaround"

My idea is that this is probably something to do with the sensitivity or other related parameters.

The issue persists after downgrading to 5.3.1

I'm also curious what "Touch Sig Workaround" is.

However, the time to finish and other statistical data are not available on FW 6.0.0 RC, which may be related to the M73 G-code..

Posted by: @hkoch

Just installed the new RC1 for MK4 which now supports Touch Diplay (if you enable it)

https://github.com/prusa3d/Prusa-Firmware-Buddy/tags

In the menu you have to enable "Touch"

 

My question is what is the menu item just below: "Touch Sig Workaround" ?