Any z probe that only occupies Z Probe connector port?

Phaedrux

The BLTouch is a little sensitive to motion during probing. It helps to add a bit of a pause after the travel move to allow it to settle. You can also increase your tolerance of probe consistency so that it will probe a few times until it's accurate.

M558 P9 H3 F100 T6000 A10 R0.5 S0.003 B1 ; P9 for BLTouch, dive height 3mm, probe at 100mm/min, travel 6000mm/min, up to 10 probes, pause 0.5s, heaters off during probing

dc42

Some bed heaters generate enough magnetic field to affect BLTouch too. So if you probe with the bed hot, you might want to use the M558 B parameter to turn off the heaters during probing.

zapta

Is there a way to repurpose one of the pins of duet wifi 50 pin extender connector as a Z stop input?

Motivation: I made a small prototype board that plugs into the extender connector and provides a connector for the 3 wire part of BLtouch (gnd, +5v, servo output). If I can use one of the signals as Z stop input I can have instead a 4 pin connector that provides all the BLTouch need.

dc42

If you don't have a DueX connected, there are 5 endstop pins available on the 50-way connector, and you should be able to use one of them. Caution: they are not 5V-tolerant! Use a 10K series resistor to help protect the pin. In firmware 2.02 the M558 command allows the selection of any endstop pin when using P4.

zapta

Thanks @dc42. I will give it a try.

My BLTouch is set to 3.3 output (confirmed by measurement) so I presume it will be ok. My goal is to have a breakout mini board that plugs into the extender connector and has a 5 pins connectors compatible with BLTouch.

zapta

@dc42 said

In firmware 2.02 the M558 command allows the selection of any endstop pin when using P4.

Thanks dc42. The documentation says to Cn but only with P4. My Z config uses P9 for BLTouch. Can Cn be also specified for P9?

; Z-Probe
M574 Z1 S2                                   ; Set endstops controlled by probe
M307 H3 A-1 C-1 D-1                          ; Disable heater on PWM channel for BLTouch
M558 P9 H5 F120 T6000                        ; Set Z probe type to bltouch and the dive height + speeds
G31 P500 X20.5 Y12.9 Z0.3                    ; Set Z probe trigger value, offset and trigger height
M557 X10:290 Y10:290 S35                     ; Define mesh grid

dc42

That's a good point. Cn is only supported for P4, because most of the other modes use the Z probe connector.

zapta

Thanks @dc42. Any chance of enabling Cn also for BLTouch?

My plan is to have a small breakout board that plugs into the extender connector and has a Z Probe connector that is compatible with BLTouch.

Will post the PCB on OSH Park so people can get it easily.

dc42

I don't even know whether the BLTouch will drive a Duet endstop input. I have not seen any documentation describing it the drive capability of BLTouch, and there are multiple versions of BTouch and its clones. So I can't recommend using an endstop input for BLTouch unless you use a logic gate or transistor to buffer the signal, in order to guarantee meeting the pulldown current requirement of the Duet endstop input.

Also bear in mind that next time we revise the Duet WiFi/Ethernet, we will probably expand the Z probe connector to be 5-pin so that a BLTouch can be connected to it directly, as it can on the Duet Maestro.

kungpaoshizi

@dc42 I would enjoy that. Not a fan of nor hater of the bltouch, but it's what I setup first, so unless I have a big reason to change it out, it will stay.