Auto home thinks midway on each axis is home

I have recently upgraded my 3DP to Marlin 2.1.2.1. For info the machine is a Geeetech Anet A8, but I don't necessarily think the printer type itself can help me diagnose.

My first question is why isn't it trying to move each axis until the end stop is triggered when I auto home?

I should say that I am using the Anet A8 settings from the configuration repository and I have checked the settings over and they seem at least sane.

I have tried with software endstops disabled.
I have tried setting the MIN_X, Y, Z values all to 0.

The behaviour is that when I autohome the axis move each ever so slightly (with the print head in the middle of each axis, roughly speaking) then it stops, still in the middle of each axis. Why could this be?

It is completely the wrong behaviour for the autohome function.

Check your endstops

Use M119 while you manually trigger the endstops with a finger

Endstop should report OPEN when not triggered
and TRIGGERED when it is triggered

I suspect yours is backwards

If they are then you need to invert them

#define X_MIN_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.
#define Y_MIN_ENDSTOP_INVERTING false // Set to true to invert the logic of the endstop.

Edited 1 time(s). Last edit at 05/27/2023 11:17PM by Dust.

Hats off to you for being able to diagnose my printer successfully from afar, from such a poorly worded non technical explanation!

I indeed found that all stops were set to invert. I switched them all to non-inverted and tested using the M119 code and now it works!!

I also was not clear on how to use the M Codes but a little research showed me that I can use the Arduino IDE using Serial Monitor and a USB cable to communicate with the Printer Controller Board.

Thanks so much.

Edited 1 time(s). Last edit at 05/31/2023 01:23AM by suityou01.