make touch leveling handmade sensor for my 3d printer

I have a board "mks robin nano ver 3.1" and I want to make a leveling sensor similar to BL Touch but simpler than that.
For this purpose, I made a coil, which is empty in the middle, and I put a plastic rod with a magnet in it, a worm track, and a magnet around the coil.
Naturally, when gravity is applied to it, the force of attraction between the magnet around the coil and the magnet attached to its inner rod attracts each other and the rod stays in place.
Now if I connect a voltage of 5 volts to the coil (it consumes a current of about 600 milliamps), it becomes a magnet and pushes that inner rod down.
I have no question about the switch part that is connected to the Z-stop socket, its mechanism is separate and has been solved.
My question is exactly how to use the three-pin port of this board (BL Touch) or maybe somewhere else! I will command this coil to energize and magnetize it after issuing the leveling command of this axis so that the pin is thrown out.
I would greatly appreciate it if you could guide me to finalize this and also let me know if there are any adjustments I need to make in Marlin as well.

Good day !

I think there are 2 ways to solve your problem. :
1 - write a completely new device using the betouch.h+ code as an example bltouch.cpp (https://github.com/MarlinFirmware/Marlin/tree/bugfix-2.1.x/Marlin/src/feature ). Surely this is a more laborious way in terms of understanding the logic of the work and the coding process itself !
2 - based on the ready-made bltouch interface, make your own device that will be completely identical to bltouch in terms of hardware interface !

Sincerely, Yuri.

This sounds like it is just like a BIQU MicroProbe with a PROBE_ENABLE_DISABLE pin to deploy/retract

Edited 1 time(s). Last edit at 01/09/2025 04:01AM by Dust.

Hi and thank you for your attention and comment
I also think too, though I couldn't exploit it with all sorts of changes in Marlin
Thank you if you can give you more guidance

Hi and thanks you.
Be sure to review the first row you wrote and announce the result

"1 - write a completely new device using the betouch.h+ code as an example bltouch.cpp (https://github.com/MarlinFirmware/Marlin/tree/bugfix-2.1.x/Marlin/src/feature ). Surely this is a more laborious way in terms of understanding the logic of the work and the coding process itself !"