Laser wiring for skr 1.4 turbo

Morning all :slight_smile: ive another question (sorry).
Im currently running lowerrider 3 on skr 1,4 turbo with the new filmware 515d , im getting excellent results:) and thats thanks to ryan and his amazing community for everyone help and support:)

My question is ive just bought a laser module (40w from laser tree (pic attached) , however im unsure wher to connect this to my board ?
Do i have to recompile my filmware ?

Ive not got a clue where to start and dont want to blow my board or my laser so thought here was the best place to start (p.s ive been searching for a day to fond a solution before asking here )

Thanks in advance

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To start with, the ‘40W’ is just marketing hype with little connection to real numbers. According to their website, this is a 5W optical module. You should be able to do engraving and cutting of thinner material with it.

Basically, you need to figure out how to power it, modify the firmware to enable laser support and define a laser pin, and connect the laser to the control board and power.

Step 1: Figure out how to power it. This is a 12V laser module. If your MPCNC is running at 12V and if you have enough headroom on your power supply, you can use the same power supply as your MPCNC. Most laser setups I see on this forum use a separate power supply for their laser. You need roughly 6A for the MPCNC and 2A for the laser.

Step 2: Enable laser support in the firmware. Laser support is, by default, enabled for the Rambo board and the SKR Pro board. It is not enabled in the V1 maintained firmware for the SKR Turbo. You need to compare the configuration_adv.h laser sections for the firmware for these two boards using a tool like Meld. I just ran the tool for you, and here is an image of the result. The listing on the left is for the Turbo, and the right is the Rambo:

I don’t know if all of these lines should be changed. The laser support has been updated with the latest firmware, and I don’t understand all of these defines. I suspect that SPINDLE_LASER_FREQUENCY should be left alone, and the other lines changed to match the Rambo configuration_adv.h file.

Step 3: Define laser PWM and Enable pins for your laser. For the SKR Pro, V1 places these defines in the top of the configuration.h file. A quick search yielded this topic where a laser is successfully installed in a SKR Turbo using pin 2.0 for the PWM, and pin 4.29 for the enable. You will not be using the enable pin, but I believe it needs to be defined. So, in the top of the configuration.h file, you can add these two lines:

#define SPINDLE_LASER_PWM_PIN  P2_00   // Servo pin
#define SPINDLE_LASER_ENA_PIN  P4_29   // WIFI block

Step 4: Compile and flash your firmware

Step 5: Connected the PWM signal line and, if needed, a ground between your laser and your control board. Assuming your cabling matches the picture on the Laser Tree website, the yellow wire in the three-pin cable will be your PWM. Pin 2.0 on the control board is the Servo pin. You can find a pinout diagram here. If you used a separate power supply, you need to create a ‘Y’ in your ground wire (black) and connect it to the control board using any ground pin. The laser and the control board must share a ground.

And you are done. You should be able to turn your laser on and off using M3/M5 commands.


Thankyou so much :slight_smile: i will try this tomorrow:)
I really do appreciate this robertbu :slight_smile:

Hey robert i tryed to compile today but keep getting this error message any ideas ?

Heres the picture of the failed build :confused:

I’m not 1000% sure, but I think the defines should be this way instead of how I listed in in my previous post.

#define SPINDLE_LASER_PWM_PIN P2_00   // Servo pin
#define SPINDLE_LASER_ENA_PIN P4_29   // WIFI block

If you get an error from P2_00, try P2_0.

If this works, I’ll edit my previous post for anyone reading this topic in the future.

Hi robert yeah that compiled fine :slight_smile: gowever im stuck again lol ive not got a wifi pin on my board :confused:

gowever im stuck again lol ive not got a wifi pin on my board

I’m confused about your problem. Most laser setups don’t use an enable pin. The reference to WIFI is just a reference to the location of what should be an unused pin. If you need that pin, here is a diagram:


If you need the full pinout diagram, you can find it here.

Found it thankyou :slight_smile: 1 last question lol as soon as it turn the power on to the skr board tje laser burns straight away :confused:

That is a problem. So here is where I would begin to troubleshoot the problem:

  • Carefully hookup a multimeter to the laser pin and ground and see if you have voltage at that pin when you turn on the control board.
  • Verify your laser supports the PWM voltage of the SKR 1.4 Turbo
  • Check/verify whether your laser module uses high or low logic to turn on.

There are firmware defines to setup the laser pin for HIGH or LOW logic for the PWM signal. Your laser pin, laser, and firmware should all have the same logic. This is just a guess as to the root of your problem. If it is the issue, here is the define to modify:


Another possibility is that the 2.0 pin might be assigned to another feature, which is turning that pin on. I have no personal experience with a laser and this board.

Just to confirm, you are hooking your laser PWM pin to the servo pin?


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Im all sorted now Robert and up and running thankyou :slight_smile: so much for your help :slight_smile:

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