Setting up Smoothieware on an SKR 1.3 in a K40: Steppers don't behave correctly

Hello everybody,
I am currently trying to get Smoothieware running on my SKR 1.3 in my K40 Chinesium.

I’m getting detailed here, because I found no instructions on the web how to use an SKR 1.3 for a K40. It’s for everybody who wants to us

I ran into several issues: first, I couldn’t deactivate the laser (active low on the PSU) even though everything was set up correctly. It turned out that the LPC1768 is a 3.3V MCU and the 3.3V on the output weren’t enough to keep the laser turned off. So I put a (bidirectional) level-converter module in between. And also I downloaded the latest official Smoothieware firmware (non CNC) and flashed it.That fixed the issue: I could now turn on the laser easily.

A level converter on the PWM input at the PSU was not necessary because on 2.75V on average the laser reached 18mA (the max you should go).

So turning the laser on and off and setting the laser power works now.

Now to my problem:
My X stepper does not behave correctly on direction changes.
When I use Lightburn to jog the axis around the steppers behave correctly, but when I try to laser a circle for example it turns out to become an S-shape. I checked my config.txt whether the dir-pin of my stepper driver is assigned right. It is set to pin 2.6 which goes along with the SKR pinout.
This is a picture of how it looks like:

I tried two different DRV8825 and a A4966 driver. I could try a TMC2209 but im sure it’s not the problem now.

Does anyone have a clue?
My config file is here
I saw in the forum the user Squid uses an SKR 1.3 as well. If you’re reading this:
Can you share your config.txt? How did you solve the 3.3V problem? Are you using a level-converter? Or a Mosfet on the 12V output?


Allright. 10 minutes later I found the problem: I mashed together two config files (one from an original Smoothieboard and another one.) Pin 2.6 was assigned twice that caused the issue. Now everything works fine. I would be still be glad about your config file, squid :smile:

Just picked up an SKR 1.3 after my C3D mini died and they are no longer available - I do not want to spend $200 for a laserboard. Would you be willing to share your working config and a little more about your setup/wiring?


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