Replacing my z-axis Opto Endtop RRS-OE with a HALL-0

It’s been a while since I’ve been able to post.   I’ve been insanely busy with this STEM event I help to put on.     So the event is over and the huge amounts of stuff I pushed to the side, are now needing to be addressed.   On of the fun projects on the the list has been upgrading the Opto Endstop sensor on the z-axis on my Rockbot.    Its been really annoying that I haven’t got the repeatability that I want out of this sensor…   Supposedly lighting conditions can affect the sensing of these units.   The sensors are good enough for the X and Y axis, but not for the z where you really need to print head in the right spot to get a good print going.

An additional item  that needed to be addressed was that I lacked a fine adjustment for fine tuning the z-height.    I was thinking about using some sort of differential screw arrangement, but than I went to musecon and some of the guys with 3d printers where raving about Hall-O sensors.

Ok.. So I bought one,  I’ve been told that you can do a direct swap with my opto sensors with Ramps 1.4 although I might need to invert an input in my firmware…
Well this requires a little bit of thought here..   (It would have been nice if I could have just soldered in the posts and just plugg in this sensor but thats not the way the board is make.  It’s made to basically solder a cable.)   The pin-outs don’t seem to be in the correct sequence anyway.optoAndHalo


Ok.. Time to rtfm. So the Hallo seems to have two modes of operation.  There is an analog mod and a Digital mode.

The downside to the analog is that the trimpot doesn’t work but you can use one sensor as a min max endstop.

The digital mode you have to have the magnet facing south but you also can get fine trim adjustment..
Do… digital it is.

So.. I wired up things up plugged it in.. The signal is inverted so I’ll need to tune that up in the firmware which isn’t to big of a deal… The thing that is irritating is that my mounting center distances are different.   As near as I can tell the center distance appears to be 17 mm (.669″).  I made a very nice split collar to mount my sensor and now I need to drill and retap it…   Hrrrg…

Ok… Now We have another issue.. the signals are inverted on the Hall-0 versus the Opto and I only have one setting to flipped that…

I had everything dialed in with Sprinter, but it appears that Sprinter can’t handle mixed signals.  Iow everything needs to be normally open or normally closed.  Quick trip the Irc indicates that Marlin is the way to go.

Calibration I tripped off the blue tape and was  checking height by offseting 10mm(.3937)   I said my gauge blocks at .403( 10mm+.009) ~ 10mm + .0035(Paper) + .0045 tape +.001

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