[PICO MMU] Sync move extruder and sp_motor do not move at the same time

[dacan2810]

Klipper version: v0.13.0-229-g3aadda6f
Pico MMU config: 0.9.2

I noticed that now, when unloading, the extruder and SP motor move sequentially
(SP motor grabs filament then stops, then the extruder unloads filament).
=> Synchronized move fails during unload.

I see an error in the code below. When I switched to legacy mode, the extruder and SP motor moved together.
In normal mode, they move in sequence => fail, which means _SP_MOTOR and FORCE_MOVE are not working at the same time.

I think this is because Klipper has changed. Even when I switch back to 0.9.1 (which worked for me before), it still happens.

 {% if legacy == 1 %}
    M83
    G92 E0
    _SP_MOTOR STOP=0 SYNC=0 SPEED={sync_speed} ACCEL={sp.motor_accel} DIST={sync_dist}
    G0 E{sync_dist} F{60*sync_speed}
  {% else %}
    _SP_MOTOR STOP=0 SYNC=0 SPEED={sync_speed} ACCEL={sp.motor_accel} DIST={sync_dist}
    FORCE_MOVE STEPPER=extruder VELOCITY={sync_speed} ACCEL={sp.motor_accel} DISTANCE={sync_dist}
  {% endif %}

[lhndo]

Hi @dacan2810, thanks for the report!
I assume that's that the latest version to date

If so, it's very likely that the latest klipper changes also broke the way the sync manual stepper mode works, in particular to this command:

MANUAL_STEPPER STEPPER=sp_motor ENABLE=1 SET_POSITION=0 SPEED={speed} ACCEL={accel} MOVE={dist} SYNC=0

from the MANUAL_STEPPER documentation:

 Normally future G-Code commands will be scheduled to run after the stepper move completes, however if a manual stepper move uses SYNC=0 then future G-Code movement commands may run in parallel with the stepper movement.

The parallel execution seems to be broken in the latest klipper version

There was an attempt to fix the manual stepper in, but it addressed a more general issue: Klipper3d/klipper@91b5e8e

You can try rolling back to this cl before all the manual stepper changes:

cd ~/klipper
sudo systemctl stop klipper
git reset --hard 17ce45d2
sudo systemctl start klipper

[dacan2810]

Hi @lhndo. Thanks for reply
I can confirm it happened on lasted klipper.
Following your guide, i rollback to 17ce45d2 and it work fine with non-legacy mode.
As soon as update to lasted, it still happen.
It take me days try fixing hotend and debug :D

[lhndo]

Thanks for testing! You pinpointed the issue well in the end.
It can be incredibly frustrating trying to set up something completely new, and not knowing if it's a problem on your side or not.

[lhndo]

I reported the issue in the klipper discourse
https://klipper.discourse.group/t/manual-stepper-sync-and-force-move-behavior-issue-in-latest/24691

[dacan2810]

Although this is not an issue with PicoMMU, should we keep it open until Klipper fixes it, so everyone is aware in case they encounter the same problem?

[lhndo]

Yep, I have added a warning in the guide regarding this issue, and also pinned it on the discord server.

[lhndo]

Hi,
I have introduced a new command to test sync behavior, called SP_TEST_SYNC
It prints some information in the console on what to expect and how to mitigate the issue.

The guide has been revised with a note about the current problem: https://github.com/lhndo/LH-Stinger/wiki/Pico-MMU#klipper