[FR] Adding option for backup Z-limit switch (w/probe)

[classicrocker883]

Is your feature request related to a problem? Please describe.

From this discussion: classicrocker883/MRiscoCProUI#244

I've had a few nozzle <-> bed crashes due to bad connectors on my 3Dtouch probe wiring, which got me to thinking as to why the Z-limit switch wasn't working as an emergency backup for just such touch probe failures.

Is there some reason the firmware can't check for both when Z-limit testing?

Also by extension, would it be difficult to add a menu option to set the Z testing method to either the Z-microswitch or the 3Dtouch, or both?

Are you looking for hardware support?

Hardware

Including, but not limited to:

Creality/Voxelab
^{basically any compatible printer}

1. Creality v4.2.2/4.2.7
2. Aquila GD32/N32/HC32 (based on v4.2.2)
3. Creality v2.4.S1_301F4 (STM32F401RC) as found in the Ender-3 S1 F4
4. Creality CR4NS200141C13 (STM32F401RE) as found in the Ender-5 S1
   These are some preliminary printer boards which would benefit most.

Describe the feature you want

Basically the idea is to utilize the Z stop/limit switch with a probe.

• Use as emergency stop
• Save nozzle from crashing into bed
• Redundant safety

Additional context

No response

[Maker-Paul]

You might want to checkout my pull request #28418