Sensorless homing direction change

General Discussion
1

Basic Information:

Printer Model: Voron 2.4 350mm
MCU / Printerboard: fystec spider 2.2
Host / SBC; Rpi 5 4gb
klippy.log

klippy.log (2.0 MB)

sensorless.cfg (3.9 KB)

Describe your issue:

Yesterday I replaced the X and Y axis motors and drivers with TMC5160. When I tried to recalibrate sensorless homing, the carriage on the X axis homed in the wrong direction (toward the end of the axis), and changing the homing_positive_dir parameter to false didn’t introduce any changes in operation. Has anyone had a similar problem and knows how to reverse this direction?

2

You can either:
Switch 2 wires on either pole of the motor
or
Add/remove an exclamation point before the direction pin name in printer.cfg

3

The latter one is more convenient.

@chomikolew :

There is also this parameter in the settings for the steppers:

#homing_positive_dir:
#   If true, homing will cause the stepper to move in a positive
#   direction (away from zero); if false, home towards zero. It is
#   better to use the default than to specify this parameter. The
#   default is true if position_endstop is near position_max and false
#   if near position_min.

Take care to not mash up the stepper direction and this parameter.

More here: Configuration reference - Klipper documentation

4

I have CoreXY kinematics, so negating the dir_pin won’t change the axis direction, it will only swap the axes with each other

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5

As I said earlier, modifying the homing_positive_dir parameter doesn’t influence the homing direction, which is what I find most puzzling

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6

You have four combinations of direction flags to use and, when I’m in this situation, I find it best to make a table and simply work through each of the four combinations of negating the X/Y stepper dir specification until I find that the toolhead is moving in the correct X/Y directions:

 X | Y | Result
---+---+----------------
   |   |
---+---+----------------
 ! |   |
---+---+----------------
 ! | ! |
---+---+----------------
   | ! |
---+---+----------------

Putting a table, like the one above, down on a piece of paper allows you to keep a record of the results and helps keep the changes straight when you’re modifying your printer.cfg and then restarting your printer and sometimes hitting the “Emergency STOP” because things are moving in the wrong direction.

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