Dual End stops not functioning

[MakerJim]

@robertbu

Wire in a pullup resistor for each endstop.

Or, you can make pigtails so you don’t have to mess with modifying your SKR board.

The quotes below are a re-paste of previous threads FYI.

MakerJimGuidance Counsellor

Dec 2024

@draglinetrash

Endstop and plug problem is eliminated I believe it is a board/firmware problem but not sure what to do now.

There’s a chance you have an SKR pro with a known issue.

Here’s the thread where it was first identified:

Lowrider V3 Endstops Do Not Trigger

Here’s what I’ve found. Attached is the schematic for the limit switch connectors from BigTreeTech manual for the SKR Pro. [image] There’s a 4.7K pullup resistor and a 1K current limiting resistor to the LED. I measured 1.7V across the LED which is fairly typical for a red LED. Looking at the voltage divider of the 4.7k/1.0K resistor, the voltage for pin 3 (signal pin) calculates to 1.98 V which is pretty much what we have measured with the DVM. So… the question is what changed? Why does …

Here’s a thread showing how this can be fixed by soldering on resistors:

Z axis homing - 1 side dropping

I was able to take a photograph while assembling my LR3 with the strut plates and new YZ plates. Hope this helps. [image]

Here’s a thread showing how this can be fixed by making a wiring pigtail adapter with integrated resistor:

Problem with x not stopping when homing

Below are photos of how to make a pigtail to solve the pullup problem without soldering to your board or do anything overly complex. Items required: 1.5k resistors HiTec Servo Terminal Kit Crimp Tool Heat Shrink Tube Process in photos: [pigtail1] I make the smallest little white wire possible so it can go into the connector and also be flexible so it can fold over in your case. I then solder the resistor wire (shortened of course) to the white wire. [pigtail2] [pigtail3] [pigtail4…

EDIT: Fixed my links (I think)