Z-Probe triggers high question

Using Arduino Mega/RAMPS 1.4 with z-probe pin = z-min end-stop pin, if my z-probe triggers high do I need to implement a pull-down resistor on the signal line, or is it pulled down by default?


  • There is no pull down with avr chips. They can be configured to have pull high in case you trigger against gnd. But for the other way around there is no config option. Is this a mechanical switch? Then all you need is a pullup configured. It does not matter if you get 5v or 0v by default - for that we can invert the signal.
  • It is a mechanical switch that goes high (i.e. 5V) when triggered, so I guess I need a pull-down resistor on the line.
    Thanks for your response.
  • No not needed if you connect gnd against switch the pull up will work fine. That is how all others do it. So

    gnd---- Switch ---- pin ( --- 5v from pullup internally)

    so when shorted it is low and when switch is open you have high from pullup.
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