Autofocus broken and crushes Z-motors

[artgolden]

Bug description
Attempting autofocus on an early FRAME prototype with board version "UC2 Standalone Board V3" moves the Z-axis motors to the limit as the first step of autofocus thereby crushing the motors past the limit. The first step of autofocus tried to bring Z-axis motors to 0 position, which was past the hardware limit.

How to reproduce
The issue is unreliable and poorly predictable.
Pressing Autofocus the second time right after previous Autofocus finished triggers it more often.

Expected behavior
working autofocus without moving to 0 as the first step.

Environment

• OS: [e.g. "Ubuntu 22.04"]
• ImSwitch version: 2.1.153

[artgolden]

Additional issue:
"STOP AUTOFOCUS" button does not stop the autofocus.

[artgolden]

Further Update: it looks like the issue happens after reloading the webUI and pressing autofocus before touching Z-axis controls. On the initial loading of the webUI after page refresh the values of the axes are all 0. And sometimes (unfrotunately not every time) it looks like the pressing autofocus makes the stage move to this 0 position as the first step.

Screenshot after webpage refresh:

[artgolden]

ImSwitch_Autofocus_broken_test_1__4_12_2025.mp4

UPD:
Confirmed occurance of moving to 0 after pressing the Autofocus button even later, not right after the page refresh. So needs further investigation

[artgolden]

UPD: I found a smi-reproducible way to trigger this behavior. Pressing Autofocus the second time right after previous Autofocus finished triggers it.

Attached video shows this as well as not working "STOP AUTOFOCUS" button.

ImSwitch_Autofocus_broken_test_2__4_12_2025.mp4.mp4

[artgolden]

UPD: the double starting Autofocus back to back is not the only way the issue happens. But other occurrences I could not predict so far.

[beniroquai]

I'll have a look!