SKR PRO v1.2 + NEJE TTL Laser

@jeffeb3. Alternately it could use G0 S<power> to turn the laser on and off… That’s what I’m doing from lightburn to modulate this…

Except that you are not just driving an old style diode emitter, you are driving the regulator IC, not the diode directly and you usually have no idea what that chip is as the numbers are commonly erased from the unit. It is fair to say the control electronics is expecting a positive going PWM signal. It may work, pulsing the ground, but you are driving the device out of spec.

Sending G0 Sxxx will only work after sending the laser on command (and having a move rate set) , so you still need either M106 or M3/4 somewhere in the command chain before the laser will actually fire. G0 also doesn’t work in GRBL, it has to be a G1 move command.

I flashed the tft firmware successfully then tried to update the firmware on the skrpro 1.2 in the tft sd port and got an illegal flash error. Now I can’t get the tft back with the same firmware. How do I get it back?

The goal is to get my creality laser working. If this firmware only works on the 5v port then is there any way to get this working in the fan0 port?

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You put the skr firmware in the skr, on the micro sd.

The tft uses tft firmware in the big sd card slot on the tft.

https://docs.v1engineering.com/electronics/skrpro/#firmware

I am building a Lowrider with SKR 1.4 Turbo configured with Marlin_V1CNC_SkrPro_DualLR_2209_2.0.7.2_510-src

I can see this is still an issue, what is the easy fix?
i am totally noob

Thanks all for making this incredible build possible…

Can’t help with your query but you are using the wrong firmware I think, there’s a separate release for the Turbo board, the one you have mentioned is for the SKR PRO.

Thanks, that might explain other issues, almost got everything else to work, all do missing z1 endstop on the M119 command😁

@pbostley ,

Care to share some pics of your setup and what ports you used on the SKR to control it. Would love a Known Working Good wiring Diagram.

I don’t have the SKR Pro, but I’ve been following the laser topics carefully. If you are running the current version of the V1 maintained marlin firmware, then laser control is enabled. V1 defines the laser pin as PC9. If you want to change it for some reason, it is defined at the top of configuration.h. The PC9 pin is on Extension-1 at the middle bottom of the pinout diagram. That section is called out here with the ground connection and PC9 highlighted in red:

And you will find a picture of the SKR Pro with the pin circled at the top of this topic.

Assuming you purchased an NEJE, your control board should look like this:

It is really plug and play. The four wire connector goes to the laser, the provided power supply plugs in, and the yellow and black pair go to your control board and use PC9 and ground.

As for controlling/testing it once installed, I’m told that the laser items on the TFT menu in the V1 maintained firmware work. It should also work using the laser items in Marlin mode. It will respond to inline commands, so you can send the following g-code:

G1 X1 S255

S values are in the range of 0 to 255, were 255 will be full power. You can also set the pin directly with something like this:

M42 PPC9 S255

And finally saw one report where M3 is also enabled, so this may also work:

M3 S255

Personally, I’d put a voltmeter on the pin and test the methods of turning the pin on before I attached the laser.

Thanks robertbu,

I ended up using GND, PC9(as PWM), and PF9 (as power on/off).
I have 2 lasers an NEJE and another that was supposed to be more powerful but was a scam (claimed 7.5w output, but is way less).

The NEJE is a much easier to use, easier to get right, and decent laser.

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Which wire did you plug up to the PF9 pin? Are you using the control board that came with the laser, or did you hook it up directly? Did you have to change anything in Marlin for the PF9 pin? I looked through the v1 Marlin firmware and didn’t see PF9 defined as anything (but I’m also new at custom compiling Marlin, so I might not be looking in the right place).

I’ll post a diagram later, but I use PF9 to trigger a SSR for the +12v. That way “SPINDLE_LASER_ENA_PIN” functions as an actual power off/on for the laser.

Thanks. I look forward to your diagram.

Do you think it’s possible to use one of the fan pins for power, instead of PF9 and a SSR? I’ve seen another post where someone used FAN 0 for the 12v, and then I’m guessing issued fan speed commands to control laser strength. From what I’ve read, PC9 controlling PWM gives better results, but I was thinking, maybe you could just set FAN 0 to 100% to turn it on and power it and then use PWM on PC9 to control laser strength, either by defining SPINDLE_LASER_ENA_PIN to FAN 0 (not sure if the firmware will let you do that) or you could just issue M106 at the beginning of your gcode, and M107 at the end to turn the laser on and off.

I picked up the Neje 40w for my lowrider, but haven’t had time yet to try and set it up. I already have way too much stuff strapped to my Y plate, so I’m hoping I can figure out a setup that doesn’t require adding another power supply, a control board and a SSR. Unless someone already knows what I described won’t work, I’ll probably give it a try next week sometime when I have a few hours to tinker.

So I have some concerns about your proposed setup, but I don’t have the knowledge, or technical details of the SKR Pro board, or knowledge of your setup, to know if my concerns are warranted. So this post is musings to consider rather than well founded information.

If the laser module is really 40W, then you will be pulling 3+ amps. If you purchased a kit from Ryan or are using a similarly spec’d power supply, it won’t provide enough current to run both the laser and the steppers.

I have only a vague idea of how multiple busses are handled on these control boards, but are you sure the fan pins are on a bus spec’s to handle higher current? If you want to pull current from the board, wouldn’t it be safer to use heater pins? For powering the laser (enable), you don’t need a PWM pin.

When using a laser, speed is beneficial to have raster operations complete in better times. One way of potentially improving speed on the LowRider would be to run the steppers at 24V rather than 12V. If you use board pins to power the laser, you’d have to move to a separate power solution for the laser.

I’m not sure what you are getting by using PF9 (vs. PC9) for PWM control of the laser. The laser control board will handle 3.3V - 12V and I doubt it draws much current, so I don’t see the need for PF9. In addition, I read that on some of the CNC control boards, higher voltage pins use ground-side switching to generate the PWM, and that has caused problems using those pins to drive lasers. I don’t know if this is true for the SKR Pro.

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So in this thread it sounds like he just has the 12v and ground hooked up to FAN 0. Maybe I understood that wrong.

And then it sounds like @mperino has PC9 as PWM for the laser and PF9 attached to a relay to turn the laser on and off.

So my thought was trying to combine all of that have everything plugged up to the SKR pro without having to use an additional power supply and that little control board, mostly because I’m trying to avoid unnecessary clutter. I’m probably overthinking things though. I tend to do that xD

I wasn’t thinking about it pulling too much power, mostly because that other thread sounded like he’s pulling 12v to power the laser off of the board, but after thinking about it, I think he might have it set up differently than what I initially read it as. So you probably stopped me from shorting something out

Edit: Also, I had a typo and said PF9 instead of PC9 in my previous post

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Here’s my summary writeup. I will add to it STL’s for the interlock key, but this should clarify and fill in some of the gaps:

@robertbu, take a look at my new summary post:

Like you I wanted to isolate the power pull from the Laser so it’s not being drawn through the board. I use an SSR (Solid State Relay) to switch the power directly from the Power Supply using the SKR as the Control. I bought mine 2 for $10 for another project, but I see equivalent ones for $8-10 for one these days.

Hi,

I haven’t found this controller board mount on Thingiverse, would you mind to share yours ?

It was just a quick and dirty bracket where the control board is hot glued to the bracket. But for what it is worth, I’ve attached a ZIP file. I included the STEP file as well as the STL.
Edit: Fixed model.
LaserBoardMountBracket.zip (28.5 KB)

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It will be cleaner than what i have now :wink:
Thanks !