Abnormal behaviour - stall homing on 3.6

ELAD

Hello,
I upgraded one of my CoreXY printers from version 3.5.4 to 3.6. This is the first one I'm upgrading to 3.6, and I want to resolve any issues before I upgrade my larger printers.

After the upgrade, the homing files behave differently.
No error messages are displayed as indicated in the chain log.
The printer does not respond to the current command M915 X Y R0 F0 S3, and must be changed to M915 X Y R0 F0 S5 to perform homing. When homing occurs, the movement seems very jerky and violent, and when X moves, Y jumps a little and vice versa, which leads to inaccuracy and inconsistency in homing.
This is a modified Voron2.4 350mm with Duet WiFi + DueX5
I am attaching the homing files with additional information.
I would appreciate any assistance regarding this issue.
If additional information is required, please let me know.
Thanks everyone,

Upgrade notes and breaking changes from 3.5.4:
There are small speed ranges that will be rejected by this release but may in practice have worked on some boards using previous firmware versions.
What does this mean in practice?

M122 after I downgraded back to 3.5.4

	M122 
=== Diagnostics ===
RepRapFirmware for Duet 2 WiFi/Ethernet version 3.5.4 (2024-11-24 10:43:42) running on Duet WiFi 1.02 or later + DueX5v0.11
Board ID: 08DGM-9T6BU-FG3SW-6J1DG-3S86T-KBVMD
Used output buffers: 2 of 26 (15 max)
=== RTOS ===
Static ram: 23488
Dynamic ram: 74044 of which 0 recycled
Never used RAM 12732, free system stack 126 words
Tasks: NETWORK(1,ready,13.4%,222) HEAT(3,nWait 5,0.1%,328) Move(4,nWait 5,0.0%,258) DUEX(5,nWait 5,0.0%,23) MAIN(1,running,86.5%,750) IDLE(0,ready,0.1%,29), total 100.0%
Owned mutexes:
=== Platform ===
Last reset 00:25:37 ago, cause: software
Last software reset at 2025-05-30 13:39, reason: User, Gcodes spinning, available RAM 16136, slot 0
Software reset code 0x0003 HFSR 0x00000000 CFSR 0x00000000 ICSR 0x0041f000 BFAR 0xe000ed38 SP 0x00000000 Task MAIN Freestk 0 n/a
Error status: 0x00
Aux0 errors 0,0,0
MCU temperature: min 35.9, current 36.4, max 39.2
Supply voltage: min 23.8, current 24.3, max 24.4, under voltage events: 0, over voltage events: 0, power good: yes
Heap OK, handles allocated/used 99/0, heap memory allocated/used/recyclable 2048/8/8, gc cycles 0
Events: 0 queued, 0 completed
Driver 0: standstill, SG min 0
Driver 1: standstill, SG min 0
Driver 2: standstill, SG min n/a
Driver 3: standstill, SG min n/a
Driver 4: standstill, SG min n/a
Driver 5: standstill, SG min 0
Driver 6: standstill, SG min 0
Driver 7: standstill, SG min 0
Driver 8: standstill, SG min 0
Driver 9: standstill, SG min n/a
Driver 10: 
Driver 11: 
Date/time: 2025-05-30 14:04:52
Cache data hit count 4294967295
Slowest loop: 15.08ms; fastest: 0.18ms
I2C nak errors 0, send timeouts 0, receive timeouts 0, finishTimeouts 0, resets 0
=== Storage ===
Free file entries: 10
SD card 0 detected, interface speed: 20.0MBytes/sec
SD card longest read time 2.6ms, write time 2.6ms, max retries 0
=== Move ===
DMs created 83, segments created 15, maxWait 33351ms, bed compensation in use: none, height map offset 0.000, max steps late 0, min interval 0, bad calcs 0, ebfmin 0.00, ebfmax 0.00
no step interrupt scheduled
Moves shaped first try 15, on retry 0, too short 0, wrong shape 1, maybepossible 0
=== DDARing 0 ===
Scheduled moves 27, completed 27, hiccups 0, stepErrors 0, LaErrors 0, Underruns [0, 0, 0], CDDA state -1
=== Heat ===
Bed heaters 0 -1 -1 -1, chamber heaters 2 -1 -1 -1, ordering errs 0
Heater 0 is on, I-accum = 0.2
Heater 1 is on, I-accum = 0.1
=== GCodes ===
Movement locks held by null
HTTP is idle in state(s) 0
Telnet is idle in state(s) 0
File is idle in state(s) 0
USB is idle in state(s) 0
Aux is idle in state(s) 0
Trigger is idle in state(s) 0
Queue is idle in state(s) 0
LCD is idle in state(s) 0
Daemon is idle in state(s) 0
Autopause is idle in state(s) 0
Q0 segments left 0
Code queue 0 is empty
=== Filament sensors ===
check 0 clear 6257966
Extruder 0 sensor: ok
=== DueX ===
Read count 1, 0.04 reads/min

From config.g

; Endstops
M574 X1 S4
M574 Y1 S4
M574 Z1 S2                                  
M915 X Y R0 F0 S3

homex.g
homey.g

Phaedrux

Please share your full config.g

ELAD

@Phaedrux

Thank you
config 1234.g

droftarts

@ELAD Can you check if M201.1 (reduced acceleration for special types of move, eg stall homing) is set? Send M201.1. I can't see it set in your config.g, but maybe the defaults are causing an issue.

Ian

dc42

@ELAD further to the suggestion made by @droftarts, if you reduce the M201.1 accelerations then you may be able to revert to using S3 in the M915 command.

ELAD

I included M201.1 X500 Y500 Z20 E500. Then, I tested the Homing, which works as usual on 3.5.4, but I get the same behaviour after switching to 3.6 — it doesn't work with S3 on M915, while for S5, the homing is still jerky, and the axes jump while each other homes.
Thank you very much for your assistance