IR Probe question

  • Hey @dc42 ,
    To increase my printable space (and clean up some wiring), I recently set up stall detection to remove my XY IR endstops.
    Reading over your comments helping other people, I thought to ask a question about using the Bed Leveling IR Probe a different way. But I started this comment mentioning I am now using stall detection to make sure you knew this was not necessarily for me (any time soon) and more of a hypothetical question.
    Could your IR Probe be used as X and Y end stops? I bet this would take some messing around as you couldn't just plug it in and make it work. They are just much smaller and would be easier to hide/install then the IR end stops I was using. Also, using Endstops on my CoreXY removed about 20mm of print space from each X and Y... I would imagine, having the DueX board could make this more likely of a possibility (as I do have) and am just really curious if this could be made a future option without creating a new Duet or X board.
    If this has been brought up before, please just link to that thread and I will read it. I wasn't able to find anything on this topic with a quick search.

    As always, thank you for your help!

  • Yes it can. The IR probe operates in two modes...analog mode when it's connected to the Duet's probe connector but it will happily operate in digital mode when connected to an endstop connector.

  • @gtj0

    Oh. I remember reading about it being able to be configured to be used as a digital device. I just forgot about it but would have still thought that it was more complicated of a device and would be more complicated to make work.

  • Nope. You can just attach it directly to any endstop connector. It senses the pullup resistor and goes into digital mode automatically. Then when the reflected IR is equal in both photodiodes it pulls the signal pin low.

  • @gtj0

    Thanks for the info!

  • administrators

    If you attach the IR sensor to an endstop input on a Duet WiFi/Ethernet, then the sensor might not pull the input low enough when the sensor is not triggered. You can overcome than by reducing the value of the 3K output resistor on the sensor, labelled R4. Or (easier than removing the old one) solder another resistor on top of it. About 100 or 150 ohms should work.

    However, IMO the IR sensor is rather expensive to use as an endstop! Have you considered using an optical endstop instead?

  • @dc42
    Per my original question, I was just wondering if or what it would take to make it work. I just removed my IR sensors to get back 20mm of bed print surface and clean up the wires and enabled stall detection. The IR Probes are smaller/ more compact, and was asking as I could hide them better. Just want to know as I like to understand my options.

    Thanks for the details on what it would take to make it work.

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