Auto-detect purge length

  • Hi!

    I just ordered this sensor in order to make measures as described here.

    I also plan to use this sensor to make an automatique purge system. My actual system moves the head over a little bucket, and extrudes a fixed amount of filament. This length is never optimal, because it depends when the last print has occurred (1min or 30min).

    The idea is to use the sensor to know when the nozzle is correctly purged. I will add a threshold in the Arduino, which will output a signal connected to the extruder endstop. Then, by issuing a command like G1 S1 E100, it should extrude the right quantity of filament. Right?

    My question is: how should I design the Arduino output to connect to the Duet endstop input? Should I use a FET or so? Or is direct connection possible?

    Thanks for your help.

  • administrators

    You can connect an Arduino output to a Duet endstop input using a Schottky diode such as BAT43 or BAT85. Connect the cathode (the end with the stripe) to the Arduino output, and the anode to the Duet endstop STP input. And common the grounds.

    Alternatively, use a 2N7000 or similar mosfet driven from the Arduino output, or a small NPN transistor with a resistor in series with the base.

  • Ok, I see. Thanks!

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