The problem when this happens (the LED lights up, but M119 reports the endstop as open) is the LED drawing too much current, and the voltage dropping at the signal pin.
The stop switch is a short to ground, which drops the voltage at that pin to logic low. When the switch is triggered, the short circuit opens, and the voltage should raise to logic high. The problem, when it happens is that the LED and current resistor pass too much, and act enoigh like the stop switch that the voltage does not raise hogh enough.
By removing the LED from the board, you remove the path for the voltage to drop, so the MCU will see the higher voltage, and read properly as triggered.
You don’t need to unsolder it. A pair of needle nosed pliers will do the job. It will most likely ruin the LED, so you won’t be re-soldering it back on the board.
A question regarding the LED removal.
I have some issues with homing the Y and Z as well, specifically Z2 axis (from the video I posted earlier). I swapped Z1 and Z2 (motor and endstops) and now majority of the problem is on Z1 axis, which means there is some issue from the MCUs E1 port or Z2 endstop port.
Should I remove those LEDs as well?
You can remove all of the endstop LEDs if you want to. But we need to make sure that is your actual issue. Are you sure that your XZ plates are able to reach your limit switch? Sometimes you have to bend those down a little bit for the endstop to be able to trigger before it hits on the YZ plate opening. On your Y is your endstop able to hit the block?
Hi. I also had the infamous end stop issue with a recently purchased kit and using the SKR pro 1.2 board. I nearly tore my hair out trying to figure out why the axes weren’t homing correctly. I would hit home X and I could push the limit switch with my hand and watch the LED blink but the motor would not stop. I confirmed the correct wiring multiple times.
I used a utility knife and just “popped” the LED on the X axis to see if it would work. I figured I could buy a new board if I fried it. Instant success. I popped the other 5 LED’s as well and I have had perfect homing since.
I miss having the LED’s to confirm my endstops were working, but I would rather be able to home successfully. I can always use M119 to find the status of the endstops anyway.
In short, breaking the LED’s worked for me. That was the biggest hiccup in my whole build, and it wasn’t even that bad. I just cut my support struts today!
Wow I’m so happy for you! I haven’t been able to do anything yet since my machine is at work (live in an apartment with wife n kids ) so I’ll do it tomorrow and really hope I can be as successful as you then
Success!! LEDs removed, tortured the machine with all types of homings and not a single issue! Maybe something worth mentioning in the manual? Thanks everyone for your patience! (On to the next issue) have a nice one!
) so I’ll do it tomorrow and really hope I can be as successful as you then 