[BUG] Robo 3D R1+ Marlin bugfix 2.1.x not homing Z axis

[LexAKABox]

Did you test the latest bugfix-2.1.x code?

Yes, and the problem still exists.

Bug Description

sorry. im new here. please excuse improper procedures. i have thoroughly scoured this site, Marlins site and everywhere else i can find, but have not found a solution.

After successfully building the firmware VIA Visual Studio Code, when homing the Z axis it only drops about 10mm and stops.
i had to reverse the Z homing direction from the original 1.1x firmware (-1 to 1) otherwise it would try to home moving up. using the arrow commands all axis move in the proper direction. i have tried a lot of different "fixes" with no change. i made so many changes, i just reloaded the original files and am starting over from scratch. i am now back on the stock configuration.h/adv.h files from the marlin bugfix 2.1.X configuration examples only changing the temperature sensor for the E3D (5). i have attached the compiled firmware as well as the config files I'm using. any help would be greatly appreciated. i cannot tell if the auto bed leveling will work as i cannot get past homing. i recognize ABL is currently not enabled in the attached files. i wanted to get the homing working as it uses the same switches. thanks again in advance everyone!

https://github.com/user-attachments/files/18790363/firmware.zip
https://github.com/user-attachments/files/18790367/Configuration.zip
https://github.com/user-attachments/files/18790368/Configuration_adv.zip

Bug Timeline

seems to be in all variants of the 2.x

Expected behavior

z axis home

Actual behavior

z axis moves down 5-10 mm and stops regardless of where it is in the plane (after swapping the z home direction. it was moving up instead of down) in all previous builds home direction is -1 but i had to switch it to 1 in order to get it to move down.

Steps to Reproduce

attempt to home z axis or all axis either via software or terminal.

Version of Marlin Firmware

bugfix-2.1.x

Printer model

Robo 3D R1+

Electronics

stock electronics other than an E3D V6 hotend

LCD/Controller

none

Other add-ons

none

Bed Leveling

ABL Bilinear mesh

Your Slicer

Cura

Host Software

Same as my slicer

Don't forget to include

• A ZIP file containing your Configuration.h and Configuration_adv.h.

Additional information & file uploads

No response

[borland1]

Have you tried debugging the hardware by connecting your printer to a serial terminal program and sending G-code to check that your z-axis limit switch is working properly?

Sending g-code M119 will report Endstop State.

> M119
Reporting endstop status
x_min: open
y_min: open
z_min: TRIGGERED
z_probe: open
filament: open

Marlin G-code M119

Endstops Reference

[LexAKABox]

i have not tried that. but it works properly with the original Marlin 1.0 firmware. i will test that when i get back into town.

…

On Mon, Feb 17, 2025, 11:49 AM borland1 ***@***.***> wrote: Have you tried debugging the hardware by connecting your printer to a serial terminal program and sending G-code to check that your z-axis limit switch is working properly? Sending g-code M119 will report Endstop State. > M119 Reporting endstop status x_min: open y_min: open z_min: TRIGGERED z_probe: open filament: open Marlin G-code M119 <https://marlinfw.org/docs/gcode/M119.html#:~:text=Use%20this%20command%20to%20get%20the%20current%20state,runout%20sensors%20are%20also%20reported%20with%20this%20command.> Endstops Reference <https://marlinfw.org/docs/hardware/endstops.html> — Reply to this email directly, view it on GitHub <#27684 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BPPOC3DCSWYXXVCPRXUMXCD2QIOLLAVCNFSM6AAAAABXDOSKVKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMNRTG44DIMJRGU> . You are receiving this because you authored the thread.Message ID: ***@***.***> [image: borland1]*borland1* left a comment (MarlinFirmware/Marlin#27684) <#27684 (comment)> Have you tried debugging the hardware by connecting your printer to a serial terminal program and sending G-code to check that your z-axis limit switch is working properly? Sending g-code M119 will report Endstop State. > M119 Reporting endstop status x_min: open y_min: open z_min: TRIGGERED z_probe: open filament: open Marlin G-code M119 <https://marlinfw.org/docs/gcode/M119.html#:~:text=Use%20this%20command%20to%20get%20the%20current%20state,runout%20sensors%20are%20also%20reported%20with%20this%20command.> Endstops Reference <https://marlinfw.org/docs/hardware/endstops.html> — Reply to this email directly, view it on GitHub <#27684 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BPPOC3DCSWYXXVCPRXUMXCD2QIOLLAVCNFSM6AAAAABXDOSKVKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDMNRTG44DIMJRGU> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[borland1]

OK, There's a Endstop Threashold Setting In the Configuration.h file, at the end of the "Endstop Settings" section. Also, a check for stuck or broken endstops.

 /**
 * Endstop Noise Threshold
 *
 * Enable if your probe or endstops falsely trigger due to noise.
 *
 * - Higher values may affect repeatability or accuracy of some bed probes.
 * - To fix noise install a 100nF ceramic capacitor in parallel with the switch.
 * - This feature is not required for common micro-switches mounted on PCBs
 *   based on the Makerbot design, which already have the 100nF capacitor.
 *
 * :[2,3,4,5,6,7]
 */
//#define ENDSTOP_NOISE_THRESHOLD 2

// Check for stuck or disconnected endstops during homing moves.
//#define DETECT_BROKEN_ENDSTOP

Might want to try independently uncommenting those #defines and see if behaviour changes.

[Maker-Paul]

I think borland1 has already given you a clue. If the Z stop is permanently triggered the Z axis will move up about 10mm and never descend. Usually this is because you need to set a pull-up #define ENDSTOPPULLUP_ZMIN_PROBE in the config.h (could be a pull down if your end-stop triggers the other way round). You probably don't need to reverse the direction of your Z stepper. Its meant to move up if the end stop is triggered.

If this fixes your issue you should close this Bug report because its not a bug.