Adding the option for Z-limit switch testing when homing on BL / 3Dtouch enabled printers?

[TekToy]

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?

[classicrocker883]

that is something I've thought too. I'll have to take another look into it, but from what I understand it can be a limitation of the board itself and how the firmware reads the pins. like it cant read both, it has to be one or the other. for instance, I tried having it so each axis could be disabled individually, but its not possible at all because they share the same connections on the board. so if you were to enable or disable one it has to be all.

[Mik-S-UMS]

In theory both the Z-limit switch and ABL could be used as they are separate pins on the CPU so I don't see why the FW can't read both, at least on the Aquila boards. I assume the 4.2.7 would be the same as is virtually identical but have no idea about other boards.

For the motors all the EN (enable) traces to the drivers are tied together to go to one CPU pin so this would mean you cannot enable just one axis.

[TekToy]

Mik-S-IMS > Yep that's your Aquila board Schematic I assume? ( https://github.com/Mik-S-UMS/Aquila-board/blob/main/Aquila%20%20board%20V1.0.3.pdf ), I was staring at it when the question arose in my mind as well.
The Z-min microswitch is connected to PA7, the BLtouch input signal is connected to PB0.

So it seems to me (in my blissful state of ignorance) there is no need for two separate firmwares, since it seems like it'd be trivial to insert an extra pin reading instruction into the Z-homing loop routine to check for either device hitting it's Z stop limit.

It might be an annoyance to people who still have the Z-switch on their machines but is currently being ignored, hence their being a useful default and the menu option to pick the appropriate Z option.

[TekToy]

Classicrocker883 > I assume those comments are referring to the older RAMPs based setups?, since on the Aquila (and I assume most modern 32bit boards) the two Z homing signals are on separate pins.

So it's a 'Ye Olde' Marlin firmware issue that insists on choosing one of the two separate signals for homing purposes?

And yes please, if you do delve into the mysterious depths of Marlin Z-homing and figure this option out, I'd be happy to test it out (not as if their aren't pockmarks in my bed texture already ;-).

But I think I'll hold off any rewiring of my board for now, (shudder!), it took way too much time tracking down the wiring issues of my el-cheapo faulty 3Dtouch to want to go through that experience again! (I somehow burnt out a trace on the motherboard BLtouch connector, don't ask me how!)

[classicrocker883]

so apparently yes, the probe and Z-min trigger exist on separate pins, I mean unless it is somehow mapped/linked or used for the probe.

I believe it may take a simple enable/disable of a config option to make this work for the first test. when I was digging through the source code I may have to force some checks, but @TekToy just let me know what your firmware .bin file is, like:

Aquila_GD32_BLT-ProUI-EX-12-26.bin

[TekToy]

I'm using - Aquila_N32_UBL-ProUI-EX-MPC- in whatever was current at the end of last year I think.

[classicrocker883]

Aquila_N32_UBL-ProUI-EX-MPC-01-27-tests.zip

Important

I'm sure you know what to do in order to test this out. so the probe should be connected in the 5-pin port, and the Z limit switch connected to the port Z-MIN (I think the connector on the stock board is blue).
When Homing, manually trigger/press the switch on 1 switch.
Repeat second Homing with other switch

Caution

!!🛑 Just be ready to KILL the power incase!!

🚫 ⚡🔌

Okay, try test ending in -t1 first.
I enabled it so when either the endstop switch or probe are triggered they act the same.

-t2 is a "too good to be true" version - its a simple change (if the first one works then this one becomes optional, would be interesting to see if it does work though)

---

edit:

here are a couple more I made if the first two don't work, or doesn't work as well

Aquila_N32_UBL-ProUI-EX-MPC-01-27-tests2.zip

[TekToy]

Cool bananas, finger on the power switch! - I'm familiar with that particular safety procedure . ;-)

I'll give it a go tomorrow and let you know how it goes.

[TekToy]

Okay T1 and T2 are decidedly ordinary, in that aside from the recent date they behave exactly like the older builds for homing, no bed cratering either, sooo...

Checked the endstop-diagnostic and Zmin isn't showing if that's relevant at all.

I'll give T3 and T4 a go.

[TekToy]

Well t3 and t4 went just like t1, t2.
Absolutely normal touch probe homing, Z limit switch seems to be completely ignored. :-(

Well thanks for taking the time to explore this none the less.

[classicrocker883]

yea there must be some kind of hard coded disable for whatever reason. I'll keep looking into it maybe someone else figured it out. but for sure the in series wiring should work, just don't have it hooked up to the Z-MIN on the board