Can NO limit switches connect to power? Instead of ground?

Using Mega board and ramps 1.4

I wired up my limit switches to power on one side, and the signal pin on the other.
Can I pull the sense pins low, and have them activate on a high signal?
Is there a way to change that in the firmware?
Or would I be better off to just rewire them?
Bryan P


  • If you have them on 5v how do you get them to ground? That is the problem here. If you connect to ground we activate internal pullup to pull signal to high and wenn your switch switches, the gnd is stronger then 5v over resistor drawing signal to gnd. The other way around it will not work. Then you need a switch that connects gnd or 5v to signal, so in that case you need 3 wires.
  • I thought there was a way to pull the Mega pin low, then trigger with a high signal...
    However, I don't even know where to begin to find the code that controls this, I don't think it's set up to be changed easily.
  • No, you can only select Pull-up or nothing. Anything else needs to be done in hardware. The firmware can trigger on high or low with or without pullup, so all 4 combination possible are selectable.
  • That was one of my three RAMPS/Arduino board burn ups.   Cost a whole $15.00 to fix.

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