Arduino Due flashed as ramps 1.6 homing fail

My NC Limit switches trigger alarm when machine is jogged to limit. However, homing cycle crashes through z max limit. Tried with UGS and gsender.

[terjeio]

Switches are wired correctly? Trigger each separately and check with $LIM command.

yes, switches are wired correctly.

[terjeio]

Homing works for me in my test setup. How are the switched wired (to min or max inputs or both)?

Both

[terjeio]

Are you homing towards max?

Yes

[terjeio]

Ok, that explains it. You have to home towards min.

Really? OMG I did not even think of trying that(neither did anybody on Reddit)

I was kinda hoping and dreading I was just a dumbdumb

So, just home all axises towards min?

[terjeio]

Yes.

Thanks I appreciate it

[breiler]

It was a long time ago that I tried grblHAL and I would like to understand this for the next person asking.

In the classic gnea/grbl there was only one input for each axis. It would not matter where you put your limit switches, as long as you configured the homing direction correctly. Default in GRBL $23=0 means that all limit switches needs to be placed in the positive direction for each axis.

And this has changed in grblHAL?

I am assuming that this is @Kickpunchy:s original post on reddit with the configuration that was used:
https://www.reddit.com/r/hobbycnc/comments/15ycwoc/homing_cycle_crashes_through_z_max_limit_switch/

[terjeio]

In the classic gnea/grbl there was only one input for each axis.

As you state legacy Grbl has no notion of min and max limit switches, grblHAL has, the core can even differentiate between limit switches and home switches. grblHAL uses the min limit inputs for homing if the driver does not support separate inputs for homing. No driver currently support separate homing inputs but that may change in the future.

It would not matter where you put your limit switches, as long as you configured the homing direction correctly.

This still applies, as long as the switches in the homing direction is connected to the min inputs. I guess I selected the min inputs since homing by default sets the home position in negative space.

And this has changed in grblHAL?

I believe not. Note that very few driver/board combinations has both min and max limit inputs - this is new in the Grbl world and may cause confusion?

[breiler]

This still applies, as long as the switches in the homing direction is connected to the min inputs. I guess I selected the min inputs since homing by default sets the home position in negative space.

If the configuration says that homing should be done on the positive end of each axis ($23=0) but you'd need to wire the switches to the min-inputs, which normally should be put on the negative ends of each axis I'd say that it is a bit confusing.

Is it ok if I make a note of it on the wiki here on $21 that the min inputs should be used?
https://github.com/grblHAL/core/wiki/Additional-or-extended-settings