[BUG] Delta homing fails

[Bob-the-Kuhn]

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

Yes, and the problem still exists.

Bug Description

Ever since PR #24951, delta printers may fail to home.

On my system, the fail happens when the head needs to move a long distance. The motors start moving and then all motors start buzzing, all motion stops and a homing error is declared.

The only work around I've found is to reduce the feedrates in HOMING_FEEDRATE_MM_M.

The git diff tool was used to narrow the failure point to PR #24951

89334caa526f2d300eee834d34d06d8f837a57d5 is the first bad commit
commit 89334caa526f2d300eee834d34d06d8f837a57d5
Author: tombrazier <[email protected]>
Date:   Mon Nov 28 03:38:15 2022 +0000

    ⚡️ Input Shaping improvements (#24951)

I looked through the PR #24951 changes and couldn't find anything obviously associated with delta printers.

This issue was uncovered in a post in the facebook group MarlinFirmware.

Bug Timeline

PR #24951

Expected behavior

Home properly using the HOMING_FEEDRATE_MM_M settings that worked prior to PR #24951.

Actual behavior

On my system, the fail happens when the head needs to move a long distance. The motors start moving and then all motors start buzzing, all motion stops and a homing error is declared.

Steps to Reproduce

1. Create a delta printer configuration.
2. Move the head by 100mm.
3. Issue G28

Version of Marlin Firmware

bugfix-2.1.x from this morning

Printer model

Tevo Little Monster

Electronics

MKS_SBASE

Add-ons

Duet Smart Effector

Bed Leveling

None

Your Slicer

None

Host Software

None

Don't forget to include

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

Additional information & file uploads

Configs.zip

[Bob-the-Kuhn]

I replaced stepper.h and stepper.cpp with pre-shaping versions. Now it works as expected.

[Bob-the-Kuhn]

In stepper.h, reverting ISR_STEPPER_CYCLES back from 100UL to 16UL makes the latest bugfix-2.1.x work as expected.

[cbagwell]

#25335 should help; if not totally fix; for this case when input shaping is disabled at compile time.

[Bob-the-Kuhn]

That also fixes it.

[thisiskeithb]

Closing since the linked PR fixes this issue:

• Don't include MIN_ISR_LOOP_CYCLES in calculation for ISR_SHAPING_LOOP… #25335

[github-actions]

This issue has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.