[BUG] G26 with SEGMENT_LEVELED_MOVES disabled with UBL has out of bound moves.

[ellensp]

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

Yes, and the problem still exists.

Bug Description

G26 with SEGMENT_LEVELED_MOVES disabled using UBL results in very long out of bounds moves in X and Y This issue happens on real hardware and simulated

Eg a 200x200 bed, X and Y moves to around 5000mm!

Bug Timeline

Unknown

Expected behavior

G26 should print a test pattern on the bed

Actual behavior

G26 Starts to print the test pattern then X and Y pull a buzz light year, (to infinity and beyond)

Steps to Reproduce

1. Build provided minimal configuration files for the Simulator
2. Send a G28
3. Send a G26
4. Watch as the simulated G26 draws 3 circles and two lines, then X and Y move to 5000mm

Version of Marlin Firmware

Bugfix-2.1.x

Printer model

Simulated

Electronics

Simulatoed

LCD/Controller

REPRAP_DISCOUNT_FULL_GRAPHIC_SMART_CONTROLLER

Other add-ons

FIX_MOUNTED_PROBE

Bed Leveling

UBL Bilinear mesh

Additional information & file uploads

Configuration.zip May be related to

https://github.com/MarlinFirmware/Marlin/issues/26718

[ellensp]

After digging around the code for a few days adding copious debugging statements Iv found the bug.

In Marlin/src/feature/bedlevel/ubl/ubl_motion.cpp

while (cnt) {

This loop never finishes and causes variable to roll over

the variable cnt is of type xy_uint8_t, ie is has a x and a y component

If I change it to

while (cnt.x || cnt.y) {

The while loop completes and G26 finishes as expected and the out of bounds move is eradicated.

I found this was modified in https://github.com/MarlinFirmware/Marlin/pull/15204/files#diff-7324a55a5383deb69d8d9506f87fe29a9046235946fcf89373d774af6144d1e7

[github-actions[bot]]

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