Analog threshold for M581 trigger

[rjh]

This is a follow-up from https://forum.duet3d.com/topic/11535/firmware-proposal-using-z-probe-as-external-trigger

I'm looking to make it possible for an analog Z Probe to act as an emergency stop when an object comes too close. I imagine that that'd happen via M581, with the Z Probe acting as a trigger when it exceeds a threshold value. From the previous thread I learnt that RRF V3.0 we can select the Z Probe pin in M581, so the one remaining obstacle is how to specify that analog threshold.

For example, we could add an A parameter to specify the analog threshold?

M581 P"zprobe.in" A980 T0 C0   ; Emergency stop any time the rangefinder detects an object too close (value >980).

How does that sound?

[dc42]

Yes that sounds reasonable. I'll add it to the work list for RRF3.

[CR3D]

Really interessting!!