Self squaring with CNC Shield 3.0

[JipeB]

Hi,
I'm using grbl 1.1h on an arduino uno with PWM spindle management enabled. The CNC Shield is a 3.0 clone which so far gives satisfaction since I control my CNC with programs generated by FreeCAD and transmitted by bCNC.

To improve operation, I tried to self-square the gantry crossmember when referencing. I modified the wiring of the CNC Shield to achieve independent operation of the Y axis motors (Y and A) and added a limit switch in front of motor A.
In jog mode, the gantry moves normally in both directions (Y- or Y+).

In the homing phase, Z and X move normally. On Y, the two motors (Y and A) move the gantry until limit switch Y closes. From this moment, only motor A continues to operate until limit switch A... which does not stop not the motor when operated. *
However, in static mode, manual action on the limit switches causes a change of state.

I specify that I followed the procedure proposed by grbl version 1.1h
to enable DUAL_AXIS.

Question: Has anyone made auto-squaring work with a CNC Shield 3.0, and if so, has the grbl limits.c file been modified?
Thank you for your feedback.
JP