Hi guys, I am new to lasers.

Hi guys, I am new to lasers. I have a hobby router CNC that I am retrofitting with a 10w laser. I just did some test runs manually triggering the laser and it looks good. My question is: how do I hook up the laser controller’s TTL input to GRBL?

I am running a GRBL that controls a generic printer port CNC driver board. Do I hook the TTL connection to the spindle enable?

Thanks for any advice! I can’t wait to get going and this board looks like a fabulous resource!


@Justin_Ahrens ​ read here https://github.com/gnea/grbl/wiki/Grbl-v1.1-Laser-Mode

Thanks! That looks like just what I need!

Ok, so pardon my ignorance, but I have a quick question. After reading the info, it seems like pin 11 is the one that is used to control the spindle. Did that pin change with GRBL1.1? I have a older GRBL shield, and for some reason, the spindle enable is connected to pin 12.

Also, if I remove the shield, and measure the voltage on pin 11 directly, while a program is running in LaserWeb, I do not see any change in voltage when the laser should be on or when it is off. I just get zero volts. Is this because the PWM is too fast to read on a plain multimeter?

Sorry for the dumb questions - I just don’t want to break my laser the first time I hook it up!

Yup, pin has been swapped.

The pins was swapped since Grbl 0.9. See https://github.com/grbl/grbl/wiki/Connecting-Grbl

For LaserWeb, you have to use the most recent Grbl 1.1!

And you need to add M4S0 to the start gcode in LW settings.

see: https://github.com/LaserWeb/LaserWeb3/wiki/Firmware:-GRBL-1.1

Thanks! I’ve already upgraded to 1.1. I’ll rewire it directly to my Arduino. I don’t really need the shield. It was left over from an old project. Thanks for the tips!

I am so close, I can taste it! I’ve installed GRBL 1.1, configured it as to the above instructions, configured the LaserWeb settings according to the above and hooked my TTL to pin 11 and ground on the arduino.

I can not get the laser to turn on, either with the manual button, or when running a program. If I touch the TTL + wire to 5V, the laser turns on, but when it is hooked to pin 11, it never turns on.

I set the max PWM setting to 1000, which is also what the laser manufacturer recommends for MACH3. I also set the laser test power to 100 and the duration to 0 which I believe makes it a toggle button, but no luck.

Any suggestions?

Ok, Disregard! I set the PWM to a max of 20000 which is what the laser’s website says and it is working! Thanks for your help.