Laser Advice and Guidance - Mesa Card

Project_Hopeless wrote: Can I leave the Z axis as is and use a phantom A axis set to a high value or does LinuxCNC need to see hardware (stepper motor)?

If you have an actual height adjustment axis then I would suggest configuring that as W and using a "phantom Z" to control PWM. Also set the Z so it moves a _tiny_ virtual amount between 0 and 100% PWM to minimise the effect on the trajectory.

M67 ought to be the correct way, but rumours are circulating here that it slows the motion (though it shouldn't)

I like the idea of ​​controlling laser power via Z-axis.
But I'm not sure how to connect it.
Maybe you can help me.

For the test, I loaded the PWM bitfile onto my 7i76e simulator.
The following lines are written in the hal.

I have now loaded a picture in linuxcnc and started the program.
I think I can get a finer structure on the lasered picture, which there is still to try.
On TB3 pin 2 and 3 I now measure 20Khz and a nicely fluctuating voltage between 0-12V depending on the height of the Z-axis.
So I can easily adjust the power of the laser with the engraving depth.
Now two questions.
Why 12V? I thought PWM was only 5V. Background: the Borad once had a short circuit. Are that 5V on a healthy board? Because laser has only  5V PWM connection.

And how can I connect the laser to the board? I only have 3 cables on the laser. PWM, GND and 12V 

The step/dir outputs (being used for PWM now) on a 7I76e are 5V signals
I suspect a measurement error

PCW wrote:

The step/dir outputs (being used for PWM now) on a 7I76e are 5V signals
I suspect a measurement error

Okay i measure now TB3 Pin 1 an 2 and got 5V max. I would wired laser this way but have fear to share thre ground.
Laser PWM -> TB3 Pin 2
Laser GND -> -12V Powersupply
Laser 12V -> +12V Powersupply
Or should  i better use  a level converter between Laser PWM and TB3 on mesa board to not share the ground?
 

If the laser module input is TTL compatible; it should be OK
as long as there is a common ground (laser GND goes to 7I76E Gnd)

If you are concerned, you could add a say 220 Ohm resistor in series with the PWM output

chris@cnc wrote:

For the test, I loaded the PWM bitfile onto my 7i76e simulator.
The following lines are written in the hal.

Code:

 

 

What version of LinuxCNC are you using? 

I haven't found any recent implementations.  Would it be possible for you to share your *ini and *.hal files when you get it up and working?