LR3 SKR v1.2 Pro connections advice please

LowRider CNC Advice
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Hi all.

I’ve got the Dual Endstop firmware and am using an endstop per motor (as shown in the v1 build doc) as well as the touch probe.

When I connect everything on the bench (prepping before final build) I see “odd” behaviour i just wanted to check whether is right or not.

The SKR Pro has a a red light for each motor (next to the pin header connection) that comes on when a limit switch for each x / y / z axis is triggered. if you have dual endstop firmware, then you also get a red light trigger when y2 or z2 is triggered.

ok so far, all making sense and normal…

So on to the perceived issue and question…

The skr pro has a driver that has 2 red jumpers in the pin header, The pin header is the 4th pin header from the motor power wiring from the Power supply connections.

Now when i connect all my limit switches and trigger them one by one, the 2nd Z switch triggers a red light on the 4th pin header, the one with the 2 red jumpers from the factory. (see image with header circled)

the question? isn’t it supposed to trigger the 6th pin header which would be Z2?

i’m going to check the marlin config / pins.h & skr_pro_common.h but… would assume the pin headers are (starting from the PSU input side)

X, Y, Z, 2xred jumpers, Y2, Z2, unused (see image)

lastly, for the Low Rider 3 build, using the SKR v1.2 Pro with dual endstop firmware, could you please confirm limit switch and touch probe pin headers? I’ve included what i think they are (see pic) Just want to make double check as they don’t seem to correspond to the build doc… (although, to be entirely fair… it’s entirely like me to have gotten myself confused, so may well be me doing something daft, hence asking for the clarity :slight_smile: :grin: :grin:

thanks in advance,

after flashing dual LR endstops firmware
after flashing dual LR endstops firmware1920×1358 364 KB

20220702_160300
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On the SKR Pro, there are 2 headers connected to the Z driver, they are wired in series, so those jumpers ore there on the second port to connect the motor. If you remove one or both of those jumpers, the Z motor will not work.

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dammit, i couldn’t find that anywhere… my “google fu” letting me down… any chance you could post the link to the thread please?

I was looking at the Skr pro manual and ofc it says you can have them run independently by removing those pins & connecting to that header, but i didn’t want to do that as the pics i’d seen on V1 showed them in place.

I do notice that some of the limits are active with nothing plugged in, is this correct? also, the diagram you posted doesn’t give me the expected results, i’ve not changed anything in marlin or on the board… but… i only get the expected results (limiter kills correct motor axis) when i connect them

Y2min, Z2min, not yet connected
Xmin, Ymin, Zmin

you diagram for comparison shows

Z2min, Y2min, Z1min
Xmin, Y1min, probe

mahoosive help mate, ty

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@josh1e

Hey, I noticed that you marked @SupraGuy’s reply as the solution, yet also posted asking for more help and saying you’re not getting expected results when implementing as shown in my diagram. Still need help?

The diagram was made for using an SKR Pro 1.2 with LowRider v3, using the stock V1 Engineering firmware for LR dual-endstop. The reason why I made that diagram was simply because SKR names some of their motor head ports and end-stop ports differently than other board makers, and some of us found the default V1 doc on dual end-stops confusing due to the naming differences. I also sought to use an image (worth a thousand words) in addition to just text.

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Hi doug. Thanks for the reply and offer mate.

Well spotted, Yea i clicked solution a bit quick :slight_smile:

I can connect everything so it works, or… as the image shows, but not both. Not sure its an issue, guess im just sanity checking what im doing.

No offense or criticism implied mate, an image is often sooo much easier lol and to be fair i did think the LR3 documentation borrowed from other v1 solutions.

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Whatever works! If I understand correctly, my diagram is just another way of restating what the V1 default docs say about dual end stops. Possible reasons why it might not work include your firmware having been edited or somehow revised, or the wiring has some issue, and maybe something I cannot think of.

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Just click the thread title from the quote.

The firmware is configured for “normally closed” switches, that is that they should be a short circuit when the switch is not triggered, and they go to being an open circuit when they are at the stop. This means that the firmware will think that the machine is at a stop when there is nothing plugged into it. This is the expected behaviour. The Z probe is the only one that is different, it detects actual contact, so it should register as open unless it is shorted to ground.

The SKR Pro is a bit broken for the TMC drivers. The diag pin on the driver must be bent or clipped so that it is not connected or else only sensorless homing will work.

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Hi everyone, thank you for all the replies. The support here is amazing.

Ok, so quick update for anyone else who may run into this.

Using m119 to check endstop status (thanks @jeffeb3) showed the diagram from @DougJoseph (thanks) was spot on and the marlin code changes made by the v1 team for the LR3 dont match the leds that light up on the board when limit switches are triggered. Everything’s working exactly as it should with the recommended wiring and default Dual endstop firmware.

Anyone else who comes across this, u can ignore those leds! They are a red herring!!

Thanks everyone!

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Appreciate the diagram!

So… Y1 and Z1 are on the left, and Y2 and Z2 are on the right (the rail side).

Posting because I missed if/where this is documented. My understanding is based on wiring colors in a pic from the LR build doc. White extension colors are being fed from the right side.

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It doesn’t actually matter, what’s important is that the endstops go with the motor.

That’s the way that I wired mine, with the second Y/Z on the rail side, but so long as I swapped the endstops along with the motors, the machine would work exactly the same way.

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Hi all,

so… today i had the LR3 moving under it’s own steam for the first time!! woohooo and no “vroom Vroom” noises!!

However, when you’ve been looking at wires for so long, it can become a bit of a blur, so… more daft questions i’m afraid. They are connection related, hence continuing this thread. Hopefully the replies help me and others and saves you all repeating yourselves (if people use the search feature :))

I have the default unmodified dual endstop firmware on my LR3 SKR v1.2 Pro.
I’m using a probe and endstops (1 for X_min, 2 for Y_min and 2 for Z) note i didn’t say Z min.

So, the questions…
With a 3d printer, z_min is as close to the bed as you can get. However the Z endstops are installed at the top of Z travel, suggesting they are Z_max. is that correct?

the reason for asking, other than needing to know where home is lol… when i home my Z it travels up to it’s max height away from the cutting board. i wanted to check all my motors are travelling in thier correct directions before moving onto the next step!

also, is the dual endstop firmware ready for a probe or is that different firmware? i assume they can be used together? endstops as Z_max and probe as Z_min?

again, the reason for asking is when i tried to home to probe, it hit the probe plate and carried on, oblivious there was a connection.

thanks

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Yes. Z homes to Z_Max. The probe should plug into Z_Min.

M119 is your friend, shoukd tell you when the Z probe is triggered.

Note that you use G38.2 to use the probe.

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Awesome, thanks for this Dan… I thought i was loosing my sanity there for a moment :slight_smile:

Ill carry on tomorrow, woohoo exciting !!

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