Before setting up homing and squaring, follow the bench testing grblhal and Initial grblHAL Setup procedures to ensure that:
Homing uses your limit switches to locate the “home” position of your CNC. Note that it will drive both y axis steppers independently until it detects the limits and then backs off a little and rechecks at a slower speed. This is important as it automatically ensures that both y axis are aligned, which ensures squareness.
You should check for squareness as described in tuning after homing as this is critical to repeatability
To configure Homing in ioSender go to the homing section and enable homing Homing→Homing Cycle→Enable
From the main screen click the Home button and the homing procedure will start. If the homing stops before reaching the limit switches with alarm 9; this is because the max travel for each axis configured in iosender has been hit before the limit switches are detected. You need to set the maximum travel distance for all axis under X/Y/Z-axis → maximum travel to the physical dimensions of your work area.
todo:
Start with Trader's discord post and PDF for squaring X gantry using a 3d touch probe and 123 block or other accurate square object