Dual Endstop Marlin, 1 stepper crashes during homing


I’m using the SKR 1.4 with DRV drivers and dual endstops for auto squaring. I test every stop using M119 commands and all stops passed the test, yet when I home X, Y or both, 1 endstop from each pair fails to function and their respective stepper will crash that end. Obviously the endstops are correctly configured, compiled, uploaded and wires all connected properly as the M119 tests all prove functional, yet when I home either X or Y, the problem occurs.

I can’t remember where I found the firmware, but it’s original name was “-MPCNC-with-SKR-1.4-Turbo-2209-TMC-Stepper-DualEndstop-master.zip”. I modified it to account for my machine and hardware, was happy that it compiled without any Extruders = 0 issues, but I can’t get over this hurdle.

Any clue what I should look for? Here’s my config files after I updated for my machine.
SKR 1.4-DRV-Dual Config Files.zip (68.1 KB)

I’d test conditions for the endstops again.

First off, all endstops must be wired independently. None should share any portion of wiring, and the switches should be wired directly back to the mainboard for signal and ground.

M119 should report individual status on switches, and should report only one or the other as “triggered” when only one is triggered. It should then report both triggered if you manually close both switches. If this does not work, then homing will not work.

If this is all working, then something else is going wrong with the homing sequence. Maybe check marlinbuilder releases for a closer fit. I think there’s one there for an SKR Turbo with DRV8825 drivers.

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My guess is that you have the X1 endstop with the X2 motor. So the motor hits the wrong endstop, stops the other motor, and continues to crash into the endstop. You can try to analytically trace the wires and check (the motor connected to the X port should match the xmin in m119) or just swap them and try it.

It is a somewhat common mistake.

There are also turbo drv firmwares compiled, but not tested in MarlinBuilder releases. It should track the latest from now on, unless it becomes a PITA.


The SKR Pro (but maybe not the 1.4?) has handy LEDs showing the state of the switches, make sure all 4 blink in the same fashion when triggered as an extra sanity check.

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Sadly, the SKR 1.4 does not have LEDs for the endstop ports, but that would be great. I’ve tested all switches independently as well as paired and they all perform as desired with M119, yet during homing sequence, 1 stop from each axis fails. If the switches were paired to the wrong steppers, both motors should still halt when both stops are pressed, yet 1 motor proceeds without a hiccup. I assure you though, my stops are paired with the correct steppers.

I also have an SKR Pro that I originally had for this Burly and it worked great, but I want to use that board for a triple Z printer and hope I can get an SKR 1.4 running this machine. Honestly, I must’ve tried 8 different Marlin repos for this board and always there is an issue or little bug that seems to only apply to my machine, lol. First it was Extruders=0 that caused the grief, but now that I’m past that, something else screws me. I guess the only thing left for me to do is try yet another repo and hope for the best.

That’s true, but if the first motor to touch stops the other motor, it will never trigger the second endstop.

I can assure you, after M119, and the stepper direction is right, there isn’t much that can go wrong with the homing sequence.

You don’t have to believe me, but I have seen this same issue a few times. It would take less than a minute to swap the endstops at the controller and tell it to home.

Another issue I have seen is that there are intermittent wiring errors in the endstops and they fail when the gantry stretches to home. But with our firmware, they would have to fail shorted, which is hard.

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I’ll switch the stop connections tomorrow am just to rule that out, but I can’t fathom that being the quirk. I’ll report back with the results.