SKR pro wiring

I just got done assembling my MPCNC Primo! It’s 24x24 and everything related to the build looks great.

I have moved onto the wiring but I think I screwed up. When I ordered I got the SKR pro board and the individual wiring kit (was going to do dual end stops in the future) but I believe that wiring kit is not compatible with this board. Also when I was looking at the wiring page it shows 6 drivers but I only have 5.

Did I miss something or do I just need to order the series wiring kit or can I make the individual ones work for now?


As far as I know, you only have to wire the steppers individually, if want to do the dual end stops. Otherwise, they are usually wired in series.
Since, you want to install the end stops at some point anyway, it probably makes sense to wire them individually from the get go. You probably need to use the dual end stop firmware though, even if you have none installed yet? I don’t know if you need to modify the code though.

What makes you think that the wiring kit is not compatible with the board? Do the connection not match?

You should be fine, even without editing the dual end stop firmware, because the end stops get wired as normally closed (NC), which means that if you don’t wire or install them at all, your machine simply will never receive a signal that a non-existing end stop is activated. More simply put, it can move freely and naively!

You have 2 x-axis, 2 y-axis, and 1 z-axis motor, so you only need 5 drivers. The image from documentation is probably a stock photo from somewhere else.

If he ordered dual-endstop wiring where each stepper is wired to a driver, then Ryan will have shipped the board with the dual-endstop firmware.

if you don’t wire or install them at all, your machine simply will never receive a signal that a non-existing end stop is activated. More simply put, it can move freely and naively!

With the way that V1 has the firmware setup, endstops are only used during homing. If the user does not try and electronically home, then then the lack of endstops installed will have zero impact. If the user does try to home, the machine will not move since without endstops, it will appear to the firmware that all the endstops are triggered.

Smartalec_87: The primary reason for endstops is to square the machine. You can accomplish the squaring without endstops by installing the endstop stop blocks and simply pushing the axes against the stops before powering up the machine.

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It was late and I was tired! Hahahah but thanks for clearing it up that makes sense now!

The only question now is….does the board have dual end stops using (extruders=0) or (extruders=1)?

Extruders will be 0. In configuration.h:

// This defines the number of extruders
// :[0, 1, 2, 3, 4, 5, 6, 7, 8]
#define EXTRUDERS 0

AFAIK dual endstops is not affected by extruder config. Actually on the Cnc you can use either config; only difference will be you see the extruder icon and temp or not on the lcd. Not sure about Ryan’s fw, but if you enable an extruder in Marlin, you should also define the dummy sensor for T0 to prevent issues with thermal protection methods.

Edit… I would do dual endstops up front… no reason to tease yourself not having it. It seems the only hurdle for you is the cost of the switches?

Not so much the cost of the switches as they are minimal….I just didn’t order them upfront and was trying to get everything up and running to test it out

On the LCD screen do you connect both wires to the SKR Pro Board allowing you to operate via touch and using the dial?

Looks like yes. My next step is electronics, so I’ve been reading over this section.

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A bit late to the party, but…

You only need 5, unless you’re wanting to add an extruder to a dual endstop machine (Or an “A” axis, which I’ve gotta say is a little tempting.)

Yes. The black 5 pin wire is for touchscreen functionality. The two grey 10 pin wires are for Marlin mode. Note that you also need the grey wires in order to use the SD card slot in the TFT. I think for the USB as well, but never actually tried that myself

You have everything for dual endstops except (maybe) the $2 switches, you might as well do it. It’s a little more setup, but really not much.

You do need to make sure that the correct switches go next to the correct motors. On the trucks, there’s a provision for a switch.

X motors go to the driver connections labelled X and E0. The motor at X needs to share the truck with the switch that goes to X_MIN, and the the motor at E0 shares the truck with the switch at X_MAX

Y motors go to the drivers labelled Y and E1. The motor at Y needs to share the truck with the switch connected to Y_MIN and the motor at E1 needs to share the truck with the switch connected to Y_MAX.

Yes actually 3 wires if you also want to use the tft sdcard through Marlin. The only setup I know that can do that on just 2 wires is the e3 board with e3 tft.

Edit; also you can’t switch between touch and dial mode while moving. Switching resets Marlin.

I have everything wired up but cannot seem to flash the SKR Pro V1.2 board. I am using the SD card that came with the board and installing just the “bin” file on the SD and then plugging that into the board. This is all done while off. Then I plug the board in and hit the reset button but I do not see and green LEDs and i cannot get the LCD to turn on either. Any ideas…I am a completely new at this…

There is no need to press the reset button. If there is a valid firmware.bin file on the SD card it should load it automatically on power up and then rename the file on the SD card to firmware.cur.

Just to double check, what firmware are you using as there are a few versions and sometimes can get confusing.

Are the lights supposed to flash? How do you verify what if the SD card has been re-named? Pull it out and put back into the computer? I am trying to download the dual end stop version for the MPCNC.

So just to go over the process:-

Download the zipped firmware called, unzip this file and copy over the firmware.bin file to the root of your micro SD card.

Place the Micro SD card into the SKR Pro board and power the board on, the board should automatically load the firmware (I think some LED’s flash but cant say which off the top of my head).

Give it a minute to load, a way you can check that the board has loaded the firmware is to power it down, put the Micro SD card back into your PC and you should see the firmware.bin file has been renamed to firmware.cur.

Okay I will give that a try……this might be a dumb question but what do you mean by installing in the “root” of the SD……do you not just drag and drop?

The only dumb question is the one that goes unasked.

It just means don’t put the firmware.bin file in a folder on the card, should have made it more clear, sorry.

Okay that’s what I did……and only the .bin file should be on the card correct? Does it matter if the drivers and such are installed….I saw that the touch screen should be disconnected

That’s correct, yes the drivers can remain installed.

Any other ideas or things to check? When I do the steps above nothing happens. Could the board be bad? It’s brand new from V1. How can I check it? Does using the usb Jack make any difference or is that for something else?