So I picked up one of those red protoneer arduino shields, and uploaded Grbl 1.1 on the arduino. I have attempted to try the Z probe by putting the wire on scl, and one, and ground and tried to trigger it manually by just touching the wires together, but it does not trigger. As I understand it should be just looking for a change I would assume to ground. But when I probe the scl pin its low on volts. Is anyone familiar with how to do this.. Every thing I see on the internet says this should work. but its not for me. So I know my dumbass is doing something wrong.