Please Help!! GrblHAL Teensy4xx Laser Mode Low voltage on PWM pin

[emilhse]

Hi guys I'm quite new in all of this I have buld laser engraver using GrblHAL Teensy4xx (i have used prebuit HEX file). And I have following problem. When I set $32=0. PWM signal Adjusts as per control software in my case its LIGHTBURN. but when i switch to Laser mode($32=1) the power is pulsing and does not exeed 1v on PWM pin. can you please advise me how can i fix this. Thanks In Advance Regards Emil

[terjeio]

Please attach a g-code program showing this problem.

[emilhse]

In my oppinion there is nothing to do with the g code. when I set it up $32=0 it works fine output on pwm pin is aproximatelly 4v but when I set it up $32=1 Pwm output is pulsing and and the max it reaches is 1v

`; LightBurn 0.9.24

; GRBL device profile, current position

; Bounds: X-54.5 Y-51.53 to X54.5 Y51.53

G00 G17 G40 G21 G54

G91

M4 ; Cut @ 100 mm/sec, 82% power M8 G0X54.5Y0 ; Layer C00 Pass 1 of 3 G1X-27.25Y-51.53S820F6000 G1X-54.5 G1X-27.25Y51.53 G1X27.25Y51.53 G1X54.5 G1X27.25Y-51.53 ; Layer C00 Pass 2 of 3 G1X-27.25Y-51.53 G1X-54.5 G1X-27.25Y51.53 G1X27.25Y51.53 G1X54.5 G1X27.25Y-51.53 ; Layer C00 Pass 3 of 3 G1X-27.25Y-51.53 G1X-54.5 G1X-27.25Y51.53 G1X27.25Y51.53 G1X54.5 G1X27.25Y-51.53 M9 G1S0 M5 ; return to starting pos G0 X-54.5Y0 M2

[emilhse]

Anyone please help

[terjeio]

Have you tuned your motor settings? Max feed rate and acceleration plays into how high the PWM voltage will go as it is dependent on the feed rate in laser mode. With default settings it will never reach the programmed rate (6000mm/min) and neither will the PWM output. The pulsing you are seeing is likely due to deceleration in corners as PWM output is reduced at lower feed rates to avoid scorching.

Everything looks normal when I run the attached program with these settings:

Note that I do not have motors attched so you may not be able to set max feed rate/acceleration as high as I have done.

[emilhse]

Thanks for your reply I will test it and let you know

[emilhse]

I did try it there was very little change.

[terjeio]

What are your $110, 120, 111 and 121 settings? What kind of laser? CO2 or LED or something else? High power? Since there are 3 passes I assume you are attempting to cut something. With the high feedrate I assume it is something very thin or that you have a very powerful laser - is that correct? What happens if you reduce the feedrate to e.g. 600mm/min?

[emilhse]

I use 40w diode laser(dual diode 15w optical output ass per datasheet) below you can see my settings

[emilhse]

I have just tested feed rate 600 $110=600 $111=600 maximum output on pwm pin is 0.5v

[terjeio]

I have just tested feed rate 600

I have done that as well and I get 3.91V, close to the expected value. Perhaps you have a faulty board?

BTW have you reduced the feedrate in the g-code file? If still F6000 then you are not testing properly. Line 11 should be G1X-27.25Y-51.53S820F600

[emilhse]

i have checked it and you were right in the g code is still showing 6000 now I'm trying to find where in the software i can change it.(lightburn)

[emilhse]

Thank you for your help. everything is working now . Thanks Again