Re: [Emc-users] M62/M63 with a pwm output possible?

[Dave Matthews]

That got it.  With the info in the thread I found a posting on the
LightBurn forums from someone trying to make a laser work on his Probotix
machine.  He had the find/replace strings in the final post.

I was using the spindle pwm pin generated by Stepconf for laser power
control.  I checked my HAL file and found that the spindle was set up on
pwmgen.0 like his example.  First try didn't fire the laser so I guessed
that the pwmgen for the spindle wasn't active until the spindle was
started.  I put in a M3 S10 before the first laser power command in the
file (an off) and things started working.  I haven't decided if I am going
to edit the HAL to add another pwmgen just for the laser or if I can find a
simple way to always have the pwmgen.0 enabled. is

Now I just need to zero in on some parameters for the burn.  I was doing a
photo of our dog and cat.  Dog came out reasonable but the black cat was
very light.  I think I need to back down the velocity as it is moving over
the pure black area too fast to do anything.

Dave

On Fri, Aug 13, 2021 at 4:34 PM Todd Zuercher  wrote:

> You might need to use M67 to set the PWM value and M62 to turn it on/off.
>
> Todd Zuercher
> P. Graham Dunn Inc.
> 630 Henry Street
> Dalton, Ohio 44618
> Phone:  (330)828-2105ext. 2031
>
> -Original Message-
> From: Dave Matthews 
> Sent: Friday, August 13, 2021 4:16 PM
> To: Enhanced Machine Controller (EMC) 
> Subject: [Emc-users] M62/M63 with a pwm output possible?
>
> [EXTERNAL EMAIL] Be sure links are safe.
>
> I recently started playing with lightburn and want to do photos.  Using
> M3/M5 Sxxx for laser control works fine for following lines but not for
> photos.  I think that I want to use M62 along with an Sxxx for laser on and
> power setting.  The laser power is controlled by PWMing the on/off pin.
>
> Lightburn likes to use M106 and an S number for laser control.  I think it
> is coming from M106 being used for fan on a Marlin 3d printer board.
> Find/Replace M03 in place of the M106 sort of works but It does a laser
> on, move, laser off so there is a lot of overburn.
>
> Sample gcode from Lightburn:
> ; Image @ 2500 mm/min, 20% power
> M8
> M106 S0
> G0X1.8487 Y0.8204 F0
> ; Layer C01
> M106 S0
> G1X0.041 F98.425
> M106 S20
> G1X0.29
> M106 S0
> G1X0.041
> M106 S0
>
> From the docs it looks like M62 would do the job if I can also use the
> Sxxx to set the pwm.
>
> Questions
>
> - Is it possible to set up the digital pin associated with the M62 to be a
> PWM output?
> - Is there an example of how to do this?
>
> Dave
>
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Re: [Emc-users] M62/M63 with a pwm output possible?

[Sebastian Kuzminsky]

I use something like this to control the heater on my 3d printer hot end.

Power transistors run high-current DC through a big resistor in a heater
cartridge in the hot end.

The power transistors are driven by a low-power PWM control signal (3.3V
logic, low current, 2kHz).  The duty cycle of this PWM signal controls how
much current runs through the resistor, which controls how much heat it
adds to the hot end.

The low-power PWM control signal comes from a Teensy PWM output:
https://www.pjrc.com/teensy/td_pulse.html

The duty cycle of the PWM signal is controlled by a PID component in HAL
(which gets temperature feedback from a thermistor in the hot end).  The
temperature command input to the PID component comes from one of the
`motion.analog-out-NN` pins coming out of the LinuxCNC motion controller (
http://linuxcnc.org/docs/2.8/html/man/man9/motion.9.html#MOTION%20PINS).

I use M67 (http://linuxcnc.org/docs/2.8/html/gcode/m-code.html#mcode:m67)
to set the temperature command to the PID controller.

Your situation with the laser seems simpler, since you don't need the PID
loop.  You'll set desired laser power with M67, and connect the
`motion.analog-out-NN` pretty much directly (maybe after some scaling) to a
physical PWM output pin.  This physical pin will connect to the control
input of the laser power supply.

-- 
Sebastian Kuzminsky


On Sat, Aug 14, 2021 at 6:40 AM Les Newell 
wrote:

> On 13/08/2021 22:25, Dave Matthews wrote:
> > I come from an electronics background and am used to looking at a scope
> so
> > have always considered PWM as a digital control mode.  I'll take a look
> for
> > examples of how to set up a pwm pin in HAL.  My initial setup was done
> with
> > StepConf so I let it do all of the work to set up a spindle pwm pin.
> >
> > Thanks.
> >
> > Dave
>
> The PWM pulse is digital (on or off) but the pulse width is analog. The
> pulse width is the parameter you are changing.
>
> Les
>
>
>
>
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[Emc-users] Smallish Harmonic drive promo

[Gene Heskett]

On Thursday 12 August 2021 11:25:37 you wrote:

> > and my life test has died. But I'm still pleased, its been running
> > for weeks non stop. So I'll knock it apart to see what broke, and
> > see if I can make a better one. But the fact that it ran for as long
> > as it did tells  me I am on the right track. :)
>
> It is sweet when a plan comes together.

Serial #3 is now running on the kitchen counter, using the innards that 
survived from #1, with the armature shunk 1mm and that space used to 
make a stronger bearing that broke. The file master.scad has been 
updated to reflect the changes after doing the autopsy on serial #1, and 
a matching README composed for my web page announcing it. Under 
Genes-os9-stf as master.scad and master.scad-README.

Enjoy, I have one of those ear to ear grins. :)

Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] M62/M63 with a pwm output possible?

[Les Newell]

On 13/08/2021 22:25, Dave Matthews wrote:

I come from an electronics background and am used to looking at a scope so
have always considered PWM as a digital control mode.  I'll take a look for
examples of how to set up a pwm pin in HAL.  My initial setup was done with
StepConf so I let it do all of the work to set up a spindle pwm pin.

Thanks.

Dave


The PWM pulse is digital (on or off) but the pulse width is analog. The 
pulse width is the parameter you are changing.


Les




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