Duet3D StealthChop triggers non existing Sensorless homing

StefanSch

Dear all,

some time ago we started setting up our 3D system (Dual Z and Dual Y) with the Duet 3 6HC mainboard. This one is equipped with the TMC2160 motor drivers.
Our system is equipped with endstopps at every axis. However, when I set StealthChop mode for the X-Axis, the homing of the X-Axis gets triggered without hitting the endstop, resulting in a wrong position of our printbed. The X-Axis is set up in a way to always work in StealthChop.

My motor config and homing protocoll looks as follows:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;                                General Purpose Input Output (GPIO) Pins
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

M950 P10 C"out4"
M42 P10 S0 ; 1V

M950 P11 C"out5"
M42 P11 S0 ; 1V

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;                                         Expansion boards
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; set current for expansion boards
M950 P4 C"out1"                                         ; Exp0
M42 P4 S1                                               ; set current Exp0 100% (24V)

M950 P5 C"out2"                                         ; Exp1
M42 P5 S1                                               ; set current Exp0 100% (24V)

G4 P2000                                                ; wait 2s for power


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;                                         Drive configuration
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; axes
M569 P0.0 S1 D3 V10      ; X backwards to adjust to coord system
M915 P0.0 S2 F0 R2
M569 P0.1 S1 D3 V1      ; Y_l forwards
M569 P0.2 S0 D3 V1    ; Y_r forwards (somehow one axis got another direction)
M569 P121.0 S0 D3 V10    ; Z_l forwards
M569 P122.0 S1 D3 V10    ; Z_r forwards (somehow one axis got another direction)
; extruder
M569 P0.3 S0       ; E0 + U
M569 P0.4 S0       ; E1 + V
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;                                         Axes/Extruder configuration
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; mapping
M584 X0.0 Y0.1:0.2 Z121.0:122.0 E0.3:0.4 U0.3 V0.4       ; set drive mapping + UVW driver for Extruder Homing

; config
M350 X16 Y16 Z16 E16:16 U16 V16                          ; configure microstepping with interpolation
M92 X160 Y160 Z400 E6400:6400 U6400 V6400                ; set steps per mm
M566 X1000 Y1000 Z200 E100:100 U100 V100                     ; set maximum instantaneous speed changes (mm/min)
M203 X1200 Y1200 Z400 E200:200 U200 V200                 ; set maximum speeds (mm/min) 
M203 I0.000001                                           ; set minimum overall movement speed to practically zero
M201 X1000 Y1000 Z1000 E100:100 U100 V100                    ; set max accelerations (mm/s^2)
M906 X1400 Y1400 Z1400 E300:300 U300 V300 I30            ; set motor currents (mA) and motor idle factor in per cent
M84 S30                                                  ; Set idle timeout

; limits
M208 X0 Y0 Z0 U0 V0  S1                   ; minima
M208 X165 Y108 Z130 U80.3 V80.3  S0       ; maxima


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;                                         Endstops
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

; mechanical
M574 X2 S1 P"!io5.in"                   ; configure mechanical endstop for X on the high end
M574 Y1 S1 P"!io6.in"                   ; configure mechanical endstop for Y on the low end io7.in not working on this setup
M574 Z2 S1 P"!io3.in"                   ; configure mechanical endstop for Z on the high end + second endstop should be added in future update round
M574 U1 S1 P"!io8.in"                   ; configure endstop for left extruder on io8
M574 V1 S1 P"!io2.in"                   ; configure endstop for right extruder on io2

The homing protocoll looks as follows:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; X Axis Homing Script ;
;        0:/sys/homex.g         ;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


; make sure it is safe to home x axis
if !move.axes[1].homed:
	M291 S3 P"Homing of Y-Axis required"
	M98 P"homey.g"

; make sure it is safe to home x axis
if !move.axes[2].homed:
	M291 S3 P"Homing of Z-Axis required"
	M98 P"homez.g"

; move Z to a save print bed distance
if move.axes[2].machinePosition < 30:
	G1 Z30

M291 S3 P"Please remove any additional equipment." J1

M913 X80         ; drop motor current to 80%
G91                ; relative positioning

G1 H1 X-300 F600   ; move quickly to X axis endstops and stop there (first pass)
G1 H2 X5 F600      ; go back a few mm

M400
G1 H1 X-10 F250    ; move slowly to X axis endstops once more (second pass)
G1 H2 X5 F250

G90                ; absolute positioning
G92 X0
G1 X105 F1000

M913 X100           ; increase motor current back to 100%

If any further Information is required to fix this issue I am more than happy to provide this!

Bests,
Stefan

gloomyandy

@StefanSch Is there a reason why you have enabled stall detection for your X axis with the following?

; axes
M569 P0.0 S1 D3 V10      ; X backwards to adjust to coord system
M915 P0.0 S2 F0 R2

I suspect that this may be triggering during your homing move. It looks like you have it configured to generate an event in the case of a stall, I'm not sure what impact that will have on the current move, but perhaps that is causing it to stop early. If you remove the M915 line does your X axis home correctly?

StefanSch

@gloomyandy
That was my attempt to maneuver around that behaviour
I tried to set the max value for stall detection, so it never gets.
I tried the setup without that line as well, but the behaviour stays the same.

If I set up the axis without StealthChop it works perfectly fine (but too loud for my application)

gloomyandy

@StefanSch Yes had a stall threshold of 2 set in that line which is much lower than the maximum (which is 63 for your drivers).

When you home your X axis how far does it move before it stops? Are you getting any sort of error message when it stops early?

How do you have your endstops wired? Perhaps they are picking up some sort of interference. It looks like you have them configured as active low, the recommended way is normally active high with the switch using a normally closed setup so that they are pulled to ground when not triggered see the notes here: https://docs.duet3d.com/User_manual/Connecting_hardware/Sensors_endstops#connecting-different-types-of-endstop-switch

StefanSch

@gloomyandy

So when starting to home the axis move some centimeters before triggering the phantom-endstop.
There is no error message or sth like this and the system just treats the axis as homed.

The endstops are wired exactly as written in that guide (between the IN and GND pin). I also did think about some kind of interference, however somehow the axis and endstops work perfectly when no StealthChop is defined.

I have the same approach for the Y-Axis where none of this behaviour occurs...
Probably I should replace that axis for further tests over the weekend (even though I don't see any reason how a phantom endstop can be set up and get triggered )

Thanks for your thoughts so far!

gloomyandy

@StefanSch I don' think you have the endstops setup using the normally closed part of the switch, if you did you would not need to invert the input (which have with the "!" specified in the endstop configuration). Your current settings are such that the endstop will be triggered when the endstop input is set to 0V/gnd. The recommended way to wire an endstop is to use a normally closed switch so that when it is not triggered the the endstop input is pulled to 0V/gnd then when the switch is triggered it will open and the built in endstop pullup resistor will raise the endstop to +3.3V and trigger the endstop event. If you had things setup this way then you would not need to invert the endstop signal with "!" setting on the pin:

M574 X2 S1 P"!io5.in"                   ; configure mechanical endstop for X on the high end
M574 Y1 S1 P"!io6.in"                   ; configure mechanical endstop for Y on the low end io7.in not working on this setup
M574 Z2 S1 P"!io3.in"                   ; configure mechanical endstop for Z on the high end + second endstop should be added in future update round
M574 U1 S1 P"!io8.in"                   ; configure endstop for left extruder on io8

StefanSch

@gloomyandy
You are totally right! I will rewire them for further testing.
However, do you see any reason why stealthChop should force such a behaviour?
So why does this never happen when stealthChop is not configured anymore ?

gloomyandy

@StefanSch I've no idea, perhaps stealthchop is generating more electrical interference?

Phaedrux

@gloomyandy said in Duet3D StealthChop triggers non existing Sensorless homing:

@StefanSch I've no idea, perhaps stealthchop is generating more electrical interference?

That would be my guess as well.