z-probe on SKR Pico

[TazwellJ]

Having an issue with z-probe not triggering on SKR Pico board. I've got it plugged into the "Probe" port on the board (which I assume is the pin 22 in the map file). Anyone else using this board that could lend a hand?
I've verified that the probe is actually good with a multimeter.
Firmware was compiled with Probe Input option selected.

[terjeio]

Shorting pin 22 to ground on a dev board works. Which pins in P21 is the probe connected to?

[TazwellJ]

So should it be connected to IO22 and P_S or IO22 and PROBE on P21? Or is P21 just supposed to have a jumper from IO22 to one or the other to determine which port should be used for probing (PROBE or WD-DET)?

[TazwellJ]

OK. Current setup is jumper on pins 2/3 on P21. Probe connected to PROBE port P13 with alligator clip on "PROBE" (IO22) and touch plate on "GND". Looking at the calibration screen in gSender, status of "Probe/TLS" just keeps randomly going from ON to OFF and back to ON. clip and plate are not currently in contact

[terjeio]

status of "Probe/TLS" just keeps randomly going from ON to OFF and back to ON. clip and plate are not currently in contact

And when in contact it is stable?

When not in contact there is only,AFAIKT, the MCU pullup trying to hold the pin at high level - IMO incredibly bad design. Add you own, one or at most a few K. Better still would be an optocoupler.

[terjeio]

What does the wd-det port of the BTT SKR Pico mainboard stand for, and what is its usage?

It could provide a proper front end for the probe, wire it between P14 pin 1 and 3. But be aware that pin 3 (VCC) should never be grounded either directly or trough the probe. E.g. if probing with a bit and the spindle is grounded then you may kill the power supply.

[TazwellJ]

That got it! Jumper on pins 1/2 of P21 and probe connected to P14 pins 1/3. Probing working. Thanks for the help!