Precision Piezo 2.75 vs 1.2

  • Hi guys, I was having some issues with the the 1st gen PCB. 1.2 I think it was. I am using in a titan aero with Re-x carriage.

    The Issue. It looks like the Sig and Ground were flopped in the 2.75 version. With the old board, connected to the duet wifi, it triggers as usual (was just having sensitivity issues). I changed the sig/ground accordingly for the 2.75, and now it is as if the board doesn't even recognize it as an endstop. Only thing that changed was the wires in the connect.

    I am getting power to the PCB, it appears to be functioning properly visually with the LCD but it the signal is not tripping duet firmware to trigger a hit even though the light is on. THoughts?

  • Update. Ok so the set up is different. I went through the new docs line by line. I am now getting the signal and showing in duet. Only thing is that when the LED is red, I am showing a number on he z-probe field, when i touch the nozzle It goes to zero. Tried reversing polarity and same thing. Feel like I am almost there, any ideas?

  • @interwebsdesigner You need to include an I1 (i1) in your M558 line, the V2.75 uses an active low signal, I1 inverts the signal for the duet.


  • @Moriquendi awesome. Ok. That worked. New issue:
    the piezo seems to be reading a minimum of 800

    1. Plugged into USB only to not trigger auto homing
    2. I tuned the pcb, the minimum reading on the zprobe is 800
    3. I set the threshold in the firmware to 1000.
    4. LEDs/Dashboard from web appear to show that it is working correctly.
    5. Plugged in main power and restarted
    6. Reading from piezo capped out at 1000
    7. No matter what tuning I tried, it remained at 1000 and can't get down to 800. When I power with USB it drops back down to 800. Not sure how to get i so it drops to a manageable level.

    Any idea what is going on or how to further tune this?


  • Can you post your M558 line? You should be using P8 with a threshold of 500, the signal range is between 0 and 1000.

    Can you tune the Uni v2.75 so that the blue led is lit and then see what the reported value is?