[Grbl_Esp32 Issue#368] Z Probe Pin Error

#1 – bdring 于 2020-03-30

On a serial monitor send the “?” (status) command with the probe touching and not touching. Paste the results in a reply.

#2 – jaysettle 于 2020-03-31

Here you are.. Did I do this correct? Thanks again.

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Additionally I tried some things. I set “$6=1″ to invert probe and the z-axis moved this time(first time I’ve seen it move after issuing the ” G38.2 F50 Z-10″ command) but didn’t stop even when I was touching and not touching.

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I have my circuit like below and using GPIO 35 (pin 14).
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#3 – derFrickler 于 2020-03-31

You probe pin is always on, thats the problem.
I guess its due to the fact that GPIO35 has no internal pull-up.
you need to add a pullup to 3.3V to turn it “off” when not touching.
see: https://github.com/bdring/Grbl_Esp32/wiki/Setting-Up-the-I-O-Pins#input-only-no-pulluppulldown
https://github.com/bdring/Grbl_Esp32/wiki/Help-with-Switch-Problems

#4 – bdring 于 2020-03-31

for some reason your pin is not changing state when going from the untouched state to the touched state. Check the voltage on GPIO35.

#5 – jaysettle 于 2020-03-31

First 3 seconds of the video it’s touching and voltage is 0.
After 3 seconds it’s not touching and voltage is in the 100mV range.

I think this supports derFrickler’s comment. I could either change the pin in the firmware to maybe GPIO 33 and move the actual probe wiring to that pin, or add a pull-up resistor. Does this sound correct?

Please let me know if you can’t view the video because of google drive permissions.
https://photos.app.goo.gl/roevKhYX3mE8rbcH6

#6 – MitchBradley 于 2020-03-31

Either way – adding the pullup or moving to gpio 33 – should work. Just try it.

#7 – bdring 于 2020-03-31

Can you send a picture of your controller setup?

#8 – jaysettle 于 2020-04-01

Yes the pullup resistor got it working thank you.

No judgement on my controller it’s working!
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#9 – bdring 于 2020-04-01

Great