Laser module does not fire up/turn on

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Hi,

I have installed a laser module to my cnc (v1.0 grbl board) but can't get it working. Reading the manual, I have updated STM32 firmware with the one form "Easy Install", upon checking the versions it says 1.1f dated for 2018 (I don't know if this is correct as the manual says that it should be later than January 15, 2020. On the other hand, I don't see version on github other than 1.1f). I did the reset and checked $32=1 and this is correct. Later, downloaded lasergrbl, prepared the file and saved the program. I've put the file onto sd card, installed in the cnc and fired the gcode. All started without any issues except the laser

Now I don't know if the file compiled for download in easy way is set up correctly with #define DEFAULT_LASER_MODE 1 or I am doing something wrong?


The laser I bought is LM-C80-24V(not to install seprate PSU) from here:

https://pl.aliexpress.com/item/10050058 ... pt=glo2pol

It should handle PWM 0/5~12V, 0~5kHz.

I have connected the power to the laser directly from the CNC PSU (24V, GND), it says it can deliver 15A of power, so should be sufficient to provide additional 1.7A for the laser at ease. Also, I connected PWM wire from the laser directly to the GRBL board into spindle PWM and spindle PWM GND pin to the PSU GND as per schematics.

Other than that, I tired to upgrade the ESP32 firmware, but it throws a lot of errors reagrding SD card and wifi config files and it does not even finish compiling. I doubt that TFT FW may have any impact on this issue, but was worth to try, unfortunatley with no luck. If this can have an impact, I will upload the errors here, if not, I will maybe open new topic later.

The laser itself gets the power as the fan spins and there is an LED that lits up.
I personally don't see a reason to install a separate PSU for the laser as in manual (I assume this is because of the default CNC 24V vs 12V laser), but maybe I am wrong?
Tomorrow I will check if the PWD and GND pins on GRBL board provide any voltage while gcode is running to exclude laser fault.

I will be very grateful for any tips on how to proceed further

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Ok, I did check and the board does not provide any voltage between pwm spinle and gnd pins. I only measured with voltmeter but I guess the volatge does not fluctuate with 50kHz for the meter not to capture the changes. Also, when I connect the laser PWM pin to 5V (next to spindle gnd pin) the laser turns on and easily burns a cardboard.

These are my GRBL settings:

$0=6
$1=0
$2=0
$3=31
$4=0
$5=1
$6=0
$10=3
$11=0.010
$12=0.002
$13=0
$20=0
$21=1
$22=1
$23=3
$24=100.000
$25=500.000
$26=250
$27=2.000
$30=255
$31=0
$32=1
$100=60.000
$101=60.000
$102=400.000
$110=2500.000
$111=2500.000
$112=500.000
$120=80.000
$121=80.000
$122=50.000
$130=540.000
$131=570.000
$132=80.000
ok
ok

I have even installed laser GRBL with the same version as in the manual, set the params exactly as in manual screenshots to elliminate bad gcode but still no joy

Are the settings pasted above enough to compile my own grbl version "custom way" so that I am sure the laser is enabled?

EDIT:

To be sure that the multimeter actually can capture any average from the PWM I connected with oscilloscope, result is the same 0.67V 0Hz. Measure of course while gcode was executing.

[rominetb44]

Hi spons,

Could you try to add a 1k resistor between 5V and S (pwm) for you mesurement ?

See U

[spons]

Hi spons,

Could you try to add a 1k resistor between 5V and S (pwm) for you mesurement ?

See U

Yes, in the mean time I found few of the topics on French section using google translate that pointed that out as well, thank you

This has partially solved the issue. The laser turns on while gcode is excecuted, but it also turns on randomly when machine is idle This is hazadrous. Is there any way out of this issue?

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I don't quite understand the logic behind this, but once I changed the pull up resistor to 10k, the laser stopped to turn on randomly once idle. I have no idea if it limited the currect enough not to start the laser and at the same time is still enough to keep the pin state as high or whatever else happended thre but the job seems to be done correctly (i need more practice with laser itself to tell for sure) and now all works (or at least for now) as expected.

[rominetb44]

Hi spons,

Thank you for your feedback.

See U