Laser always on

arhi

@arhi please tell me how you did it? how did you raise it to 5 volts? And what was the piece of config.g and the circuit at least by hand, how did you connect it?

originally I used same circuit as you have here

so 3v to 1AB and 1Y to 2A and heater3 to 2B, this inverts the output of the heater3 and outputs it on 2Y at 5V level, and that 2Y I connected to PWM input on the laser driver (it is some aliexpress 15W laser with external driver that has a fan on itself)

and this made laser ON during idle, when I do G1X10S255 the laser goes off, if I do G1X10S125 laser goes to 50% power, G1X10S10 laser go to 90% power ..

so this driver obviously need non-inverted signal so what I did is just REMOVE the whole 74hct02 and connected HEATER3 DIRECTLY TO PWM on the laser driver, obviously this laser driver do not have a problem with 3V on the pwm so no need to get the signal up to 5V

when I power on duet laser blinks for a moment (milliseconds or less) and is off, when I do G1X10S10 it is at 10% during the move, G1X10S255 it is at 100% during the move, and it is off after the move

The only config line required:

M452 C"exp.heater3" F100 R255 S0 ; laser uses heater3 pin,  PWM frequency 100Hz, 0-255 is 0-100%, not sticky use S with G1

shiga

@arhi I did as you said, I connected the pwm directly, the laser was controlled, but not at full power, it was very dim, and did not shoot at S255. The macro to turn on the laser mode is as follows:
M563 P0 D-1 H-1; clear tool
M563 P0 D0; create a tool - no heaters
M307 H3 A-1 C-1 D-1; Clear heater
M452 P3 R255 F20000 I0
what should I do next?

arhi

@shiga so if you do

G1X10S0

your laser will move and will be OFF

and if you do then

G1X20S255

it will move and be ON but not 100% ?

shiga

@arhi said in Laser always on:

so if you do
G1X10S0

your laser will move and will be OFF
and if you do then
G1X20S255

it will move and be ON but not 100% ?

yes, quite right. g1x10s10 is dim, g1x10s100 is brighter, g1x10s255 is off. and if g1x10s250 also shines like on s100.

arhi

dunno, that makes no sense to me, maybe your driver requires 5V pwm and will not work with 3.3V pwm, so you need to use that hct02 to up the signal to 5V but you need to get that signal trough one more part to invert it .. so instead of using 2Y as output, feed 2Y to 3A and 3B and use 3Y as output (should be inverse of what 2Y was)

shiga

@arhi Many thanks for the help! the problem was resolved, it was a bad 74HCT02, from a batch of 5 pieces all were inoperative, replaced from another shop and it all worked!
small question: which program is the best to use for engraving with DUET?

arhi

@shiga said in Laser always on:

bad 74HCT02

auch

small question: which program is the best to use for engraving with DUET?

no idea. I know that visicut is often mentioned on some forums for DIY machines (grbl, smoothie...) but I have never owned an engraver and the small experience I do have with it I generated the code myself using c so I doubt anyone would fund that useful ... probbly someone with engraver can give you some hints but probbly setup a specific topic for that on forum as that will give it more visibility

arhi

btw how do you know your laser is outputting X% at any time (not knowing what the PWM pin is doing) ? you have something to measure the ray impact or ?

shiga

@arhi I'm looking at the current consumption.

shiga

@shiga said in Laser always on:

@arhi I'm looking at the current consumption.

I look at the current consumption, and compare it with the PWM of the signals from the servo tester.