M915 stall detection problems with sensorless homing

Jimmykc

I have a Duet3 MB and my firmware is MB6HC 3.1.1. I am configuring the X axis to test sensorless homing.
If I set M915 X S2 R0 F0 H200, it appear the motor turn clockwise then it stop. I think it present the motor happen stall detection.
If I set M915 X S3 R0 F0 H200, it appear the motor turn counterclockwise continuously. I think it present no happen stall detection. I try to stop motor but no response.

My config.g is show below :
M584 X0.0 Y0.1 Z0.2 U0.3 V0.4 W0.5 A1.0 B1.1 C1.2

M350 X256 Y256 Z256 U256 V256 W256 A256 B256 C256 I1

M92 X17066.33.00 Y17066.33.00 Z17066.33.00 U17066.33.00 V17066.33.00 W17066.33.00 A17066.33.00 B17066.33.00 C17066.33.00

M566 X900.00 Y900.00 Z12.00 U900.00 V900.00 W900.00 A900.00 B900.00 C900.00

M203 X6000.00 Y6000.00 Z180.00 U6000.00 V6000.00 W6000.00 A6000.00 B6000.00 C6000.00

M201 X500.00 Y500.00 Z20.00 U500.00 V500.00 W500.00 A500.00 B500.00 C500.00

M906 X800 Y800 Z800 U800 V800 W800 A800 B800 C800 I30

M84 S30

M574 X1 S3

M915 X S2 R0 F0 H200

My homex.g is show below :
M913 X70
M400 G91
G1 H2 Z10 F12000
G1 H1 X-320.5 F5000
G1 H2 X5 F5000
G1 H1 X-320.5 F5000
G1 H2 Z-10 F6000
G90
M400
M913 X100 Y100
M400

dc42

First of all, don't use native x256 microstepping in M350. The required step rate will be too high at high speeds. The default x16 with interpolation works well in most cases, although extruders with low steps/mm sometimes work better at x32 or x64.

If that doesn't solve the problem, try reducing the current further for homing in your M913 command.

Make sure that the belt is tight enough to provide a hard stall and avoid any possibility of the belt jumping teeth. Choose the homing direction so that the length of belt between the carriage and the motor pulley that is under tension is short at the point of stall.

Jimmykc

@dc42 I can do stall detection when I use native x16 microstepping in M350. Thanks.