I need some help! I´m not a Engineering, not even beginer

Hi I´m building the MPCNC F25 , I´m ok with the assembling of the general pieces, printing and cutting is going ok for mi knowledge.

I arrive to the point of the electronics and im COMPLETELY LOST. I got the " BIGTREETECH TFT35 V3.0 + SKR V1.4 Turbo" but a part from that I never did any configuration in my life.

I hope someone can give me a hand.

Thanks in advance

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Before someone can help you, you need to provide the information (or a link) on what control board you purchased and the stepper drivers you are using with that board. This name I believe is just this display, so only the screen.

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This is true, my bad, i have the SKR V1.4 Turbo

This is as far I arrived

So you don’t have any stepper drivers at this point?

well, I think I have all the components, from the list, i just got stuck in this point. I didnt try to plug the SKR to the laptop. all arrive last weekend.

The board pictured does not have any stepper drivers plugged into it. Not sure if the SKR 1.3 firmware will work without modifications. The easiest path forward is to use either TMC2209 drivers or DRV8825 drivers (since that is what V1 uses with the SKR boards). With the info about which drivers, someone (probably jeffeb3) can point you at the right firmware to use as a starting point.

I don´t know if is need, I have another kit with steppers drivers, ARDUINO uno that has a CNC shield that has the steppers. As I said all is new for me.

I will try to contact maybe he can help me a bit.

@jeffeb3 Could you check on my ploblems :wink:

I’m watching. Robert has been right in so far.

The turbo is a bit trickier. It would have been easier to get an skr pro. You do need drivers. Can you share a photo of what you have?

Hi, so fast!! so this is what I have:

I have 4 steppers drivers.

Those look like drv8825. You will need to set the vref on them (0.7V is a good start).

You need to wire the double axis in serial.

There is a config I just added to the marlinbuilder for turbo. It is not tested. But this should be a good enough starting place:


You will need to log in to download it. The firmware.bin can just be put on the sd card and it will flash it. No need to compile it.

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Well!! I have to tell you that in not familiar with any of this, at all!! I´m trying to learn

This i learn or watch it how to do it, today, so as you can read I´m baby in all of it

I will check it out, Thanks

I can reach the link!?

You need to be logged into github.

DONE!! so now? :wink:

I don’t have an SKR board of any sort, nor a TFT, so the information I’m going to give you comes from reading in the forum and understanding generally how all the pieces of an MPCNC fit together First, for a selected number of control boards, V1 maintains tested firmware. Using one of the boards is the easiest way to get your MPCNC up and running. The SKR V1.4 turbo is not one of those boards. There are people using the SKR V1.4 turbo for an MPCNC, but they are few, and I don’t know if any of them are active on this forum to help you with your specific board. So you are in for more work and probably more frustration to get your MPCNC working with SKR Turbo board. That is why Jeff mentioned the SKR Pro 1.2. That is a board they do have a tested and compiled firmware for, plus all you would need to do is drop a file on the SD card, and the firmware would get flashed when the board is powered on. No compilers or other “engineering” tools required.

Your board is more difficult. I was surprised that Jeff had any firmware source for the board, but to be clear, it is untested, and uncompiled. While you may get lucky, I would expect some challenges getting the firmware running correctly on your board. The instructions on how to compile and upload the firmware can be found here.

Stepper drivers sit between the control board and the stepper motors. They take a command from the control board to take a (micro)step, and translate that in the a specific pattern of energizing coils. A control board also limits the amount of current going to a stepper. Too much current and they can overheat. Some stepper drivers include a communication protocol that allows the the firmware to set the current. Other stepper drivers are dumb and require the current to be set manually using a multimeter. The DRV8825 one of the ones that requires you to manually set the current. The other driver I mentioned above, the TMC2209, is one of the smarter ones. If you were using V1 tested firmware, the currents would set by the configured firmware.

Most MPCNC machines have the driver current set between 0.7A and 0.9A. While your stepper may have a max current much higher that this range, using currents higher than these values can lead to overheating on the MPCNC. For the DRV8825, the reference voltage you want to set it to half of the max current. I’m guessing that Jeff meant 0.7A, which translates to a voltage of 0.35V. Here is one video on how to setup the DRV8825. Use the 0.35V reference, not the one he calculates in the video. There are a lot more videos plus many web pages on setting the current on a DRV8825.

Your TFT has its own firmware. You can probably follow the TFT instructions at this link to get the correct firmware on your TFT.

One final note. There are two configurations for wiring the steppers for the MPCNC. One requires only three drivers , but requires a special harness that you must buy or configure. The other configuration requires five stepper drivers (you currently only have four).

PS. The firmware you downloaded will have a ZIP file that contains another ZIP file. You need to unzip both and move the source (file folder named Marlin) to your machine.

Edit: If you are wiring your steppers in series, the wiring diagram of the harness is on this page.


The code is compiled. I do have a turbo sitting on my desk. I haven’t done anything with it, but I did test the serial 2209 variant and the 2209 dual LR versions to make sure I had the dual endstops on the right pins. I never connected motors (but I did connect drivers).

Take that as you will. Starting with the Skr Turbo is going to be some work, and you’ll need to figure out what works for you, or maybe find someone else here running a turbo (they are around). But there is a 25% chance you won’t have to compile the firmware and what we have will work without even installing platformio. Otherwise, it will be a better starting place than vanilla Marlin.

No, when we had ramps everywhere, we would always start with 0.7V for every motor. It was a good starting place. The DRV8825 amperage is max, not RMS, so a 1.4A on a drv8825 is about 1A on a TMC, and the drvs can handle it just fine. More than that, and you’ll need a fan. Just watch the motors to make sure they don’t get too hot (up to 50C is fine).

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The code is compiled

I looked at Marlin version you linked Carlos to, and the only bin file I found appeared to be the boot loader. That is why I assumed it had not been compiled.

No, when we had ramps everywhere, we would always start with 0.7V for every motor. It was a good starting place. The DRV8825 amperage is max, not RMS, so a 1.4A on a drv8825 is about 1A on a TMC, and the drvs can handle it just fine.

Sigh. Just when I start to think I’m starting to figure out stepper motors and drivers.

The truth is, it doesn’t have to be that precise. Most problems are pretty obvious and there is a large envelope of good settings. But I think 0.35V is probably too low.