[Grbl_Esp32 Issue#236] Connecting the 2.5d pen/laser to Chinese laser cutter

#1 – bdring 于 2019-09-28

The laser PWM pin was intended for laser power control of small lasers. I have tried it on some blue diode laser modules. The signal is only 3.3v, so some laser power supplies may have issues with that.

You idea with the FET and a pull-up might work too.

You can map virtually any function to the laser PWM and Servo PWM pins in the cpu_map.

Be careful. That is a dangerous power supply and laser.

#2 – misan 于 2019-09-28

I would rather use a bipolar transistor.

#3 – brakthehun 于 2019-10-04

I typically connect to the TTL H and I set up my manual fire button from TTL L to ground.

#4 – kjjordans 于 2019-10-13

Hi Bart,
I have a level shifter to convert to 5v, how do I set the servo PWM pin to the Spindle/laser enable in the CPU map? I can’t find the option.

Also, is the dynamic laser power from gbrl1.1 implemented in this branch?

#5 – bdring 于 2019-10-13

The spindle (laser) pin is on GPIONUM17 the servo is on GPIONUM27. The Laser Pwr PWM pin should work as defined. If you want to use the servo PWM pin rather than the Laser Pwr PWM, you would comment out #define USINGSERVO and change #define SPINDLEPWMPIN GPIONUM17 to #define SPINDLEPWMPIN GPIONUM_27

Dynamic Laser Power is implemented. You need to turn it on with $32=1

#6 – kjjordans 于 2019-10-14

Sorry, I was a bit vague.
I would like to keep the laser PWM as is. I want to change the servo PWM to laser/spindle enable and connect it to TH on the PSU. I think that is the correct way to connect this PSU.

Otherwise, I could short TL to ground (or TH to 5v) to make the laser fire with only the PWM signal.
I don’t know if having the enable pin gives any better functionality or safety over relying on the PWM signal
Do you think that there is any need to use the enable pin

#7 – bdring 于 2019-10-14

You can try it. Define a spindle enable pin and assign it pin 27. You only need to change the cpu map file.

#8 – kjjordans 于 2019-10-14

So
#define SPINDLEENABLEPIN GPIONUM27
in the CPU map?

#9 – bdring 于 2019-10-14

Yes, comment out any other uses of GPIONUM27. Commenting out this should do it.

“C++
//#define USING_SERVO // uncomment to use this feature
“

#10 – kjjordans 于 2019-11-25

Hi,
I have got everything working. I am using the servo PWM which is 5v for the laser PWM and i am using the laser power PWM pin with a level shifter for laser enable.
the level shifter is similar to this one. (thanks sparkfun)
!image
The only problem that i have now is a small spike at startup and reset that is causing the laser to fire.
Any ideas on the best way to stop this? I thought of inverting the enable pin and attach to TL, that way I would need a high signal on the PWM and a low signal on the Enable which i think is unlikely to happen accidentally. What do you think?
!image
notice the small spike as i turn the power on and the long spike during start up. the same signal happens when i restart, only a bit longer.