Question X Endstop connections on Nitehawk-SB Board

[Rusty105]

So... I am instaling the Nitehawk-SB toolhead board on my new Switchwire build (almost done) and I am trying to wire up the X-Endstop. The toolhead board has a plug for XY Endstops so I thought that would be a good spot to wire it up, I am just confused on which pins to use. The plug has pins GND, X, Y, 5V. I have a microswitch mounted to the carrage and wires soldered to C & NC (common and normally closed) as per the Switchwire assembly manual. Obviously I use X as one of the connections, but is the endstop switching 5V or GND?

Thanks!!

 

[shadow_steve1]

Just use pins GND, and X and you'll be fine you dont need the 5v at all

 

[NoGuru]

If my memory is correct, you should not need 5v, just signal and GND. Open or closed.

 

[Rusty105]

I was thinking the same, but wasn't sure if the toolhead board wanted to see GND or 5V on the GPIO pin.

 

[kharrisma]

Typical limit switch circuit is just utilizing the NC tips (if it has 3 terminals, otherwise it's just a 2-terminal NC switch) to supply a path to ground for a low-voltage (typ. 3.3V) feed from the control card (through a current-limiting resistor.) Switch closed, 3.3V to ground, MCU sees nothing (pin is low.) Open limit switch, no more easy path to ground for the 3.3v signal, instead it goes to the only other place it *can* go, through a low-value resistor to the MCU pin that's monitoring the stop switch, making that pin go high = switch tripped. I'd be *very* wary of putting 5v into that circuit. You're unlikely to damage anything using X and ground; worst you'd likely see there is the switch failing to work properly. You *might* damage something using 5V and X, though. This is generally true of printer control cards, but I'm unsure exactly how an SBC handles the limit switch circuit, likely the same but can't say for sure. A reference to the Nighthawk 36 elsewhere here was a lucky find, and I'm just now looking into it to get rid of as much of the troublesome wiring to the hot end as I can! Both the umbilical and the drag chain approach had issues.