Z axis limit switches

[cpapplefamily]

I have a picoCNC running the grblhal firmware. The board has limit switche accommodations for A,X,Y,Z. I'm currently only using X,Y,Z for a laser table. I would like Z to have both positive and negative limit switches.

Can someone point me to an example to how of possible to set this up?

We will likely be adding a rotary axis on the future so I will likely enable Axis A bit will not need the limit

[terjeio]

The RP2040 driver currently does not have support for max limit switches so creating a custom map file is not an option.
Easiest is to connect both switches to the Z limit input, normally closed (NC) switches in series, normall open (NO) in paralell. There is a small problem with this though, if homing is initiated with one of the switches triggered the homing routine cannot know which direction to pulloff. To avoid a crash in this scenario "Two switches shares one input pin" (bit 4) in the $22 setting should be enabled.
$$=22 output:

    0 - Enable (1)
    1 - Enable single axis commands (2)
    2 - Homing on startup required (4)
    3 - Set machine origin to 0 (8)
    4 - Two switches shares one input pin (16)
    5 - Allow manual (32)
    6 - Override locks (64)
    7 - Keep homed status on reset (128)

[cpapplefamily]

Thanks for the great answer. BTW where did you get that Bit Map? The https://github.com/terjeio/grblHAL/blob/master/doc/markdown/settings.md does an ok job with many of the settings but this particular one it does not

[terjeio]

It is not a bitmap, it is text from the controller copied from the output returned from sending $$=22 to the controller.
See the Wiki for new commands that can be used to get settings-related information from the controller. BTW your link above is to the old grblHAL repository which is now way out of date.