Marlin firmware as laser cutter

Re: Marlin firmware as laser cutter

o_lampe — Thu, 23 Mar 2017 03:37:42 -0400

I just made a voltage divider to reduce 12V FAN output to 5V. No inversion necessary.

Regarding LED power regulation: It's true what you said about LED controllers, but there are 12V LED modules that can run directly on 12V without current limitter. Those modules can be PWM controlled by a Fan output. I'm using LED rings called "Angel Eyes". It's a car front light assessory made for 12V.

Re: Marlin firmware as laser cutter

AngelOfGrief — Wed, 22 Mar 2017 11:12:51 -0400

I don't know if this has been already solved, but I would like to point out that all high power outputs on RAMPS 14 (that is, fan, extruder heater, bed heater) are OC (open collector) outputs. This basically means, that the MOSFET itself only drives the output to GND and does not provide any particular voltage on output. Check out the schematics:

[rigidtalk.com]

If you look carefully, you'll see, that negative out of D9 is driven by the MOSFET, and positive out is wired to +12v directly. So, to have 0....5v range for D9 output, just use a 1k resistor between MOSFET out and +5v power supply. So, when MOSFET is active (open), your output will read 0v, when MOSFET is not active, it will be +5v. Note also, this causes the logics to be inverted (which Marlin firmware is aware of). If you redefine the FAN pin to a servo output, you will lose the inversion and the voltage on PCM out will be reversed relative to M106 command setting.

For those folks trying to drive a 12v LED module directly from the FAN output. Bad news, most likely it will not work. The reason is, the LED itself is not powered by 12v, and the module that you purchased has a regulator. So, whenever you try to control LED power by PWM output of your RAMPS, the regulator takes "care" of it and feeds the LED whatever it's required. So, the correct solution would be to power your LED module directly from a 12v power supply and use a PWM control INPUT pin that your LED module SHOULD have besides the +12v pin. In case it doesn't, it's, again, bad news for you. :)

p.s. MOSFETs do not have a collector, but essentially, it's the same. :)

Re: Marlin firmware as laser cutter

tgmelo — Tue, 23 Aug 2016 13:21:51 -0400

I bought a laser head that I connected to the d9 output, but it's ON from the start.
It doesn't respond to any Gcode command to turn it off or decrease power. And yes, 13_EFB. The PMW works fine for my layer fan.
I've checked everywhere but I cannot find an answer.
The company that sold me the unit isn't of much help either. They say it worked fine on their printers and the unit was tested before shipping, so I must be doing something wrong. Just don't know what can it be.
Must I do some changes in Marlin in order to make it run?
Thanks in advance for any tips.

Re: Marlin firmware as laser cutter

Cromaglious — Mon, 08 Aug 2016 00:43:09 -0400

The D9 mosfet on the RAMPS board (all the mosfet's actually) switch the negative leg of the PS connector closest to the mosfets. I use a wall wart with 12v pos going to a relay board, and the negative of the wall wart tied to the negative terminal of the PS connectors on the RAMPS 1.4, the negative from the relay board goes to the D9 negative line of the screw connector. you could do the same thing with a 5v supply as well.. PS negative to the negative PS connector, posative to your device, and the negative from the device to the D9, D8, D10 on the RAMPS mofests screw connectors. I don't even use the positive terminals on the mosfet blocks. This also works on the MKS 2560 boards as well.

Re: Marlin firmware as laser cutter

Downunder35m — Tue, 26 Jan 2016 06:50:21 -0500

If you still want to use Marlin to make a laser cutter / engraver have a look here.
I modified the already modified Marlin firmware to suit my china laser cutter.
The actual workings underneath are still plain Marlin, just with the additions for the laser use.
Should be pretty straight forward to convert for your needs, bed setup, stepping and endstops and off you go.

Re: Marlin firmware as laser cutter

VDX — Mon, 18 Jan 2016 15:18:15 -0500

... yes - if you don't support the Arduino with the PSU, then you have to 'define' a basis potential as GND, which defines the signal voltage to drive the TTL input of the laser driver.

Otherwise -- without any sort of back-connection, the voltage is 'floating' without the ability to trigger the input ... or may even be totally wrong defined, so your Arduino-PWM-output can be something like let's say +30V or maybe even -50V off (possible random 'floating' switching potentials of different PSU's without proper ground level), what will immediatly destroy one of the devices or both ::o

Re: Marlin firmware as laser cutter

jeyton — Mon, 18 Jan 2016 12:47:18 -0500

Whoa really? for some reason I didn't think that would work well. So correct me if I am wrong, but this is how I would want to wire it?

PSU GND + Arduino GND <-------> Driver GND

Arduino PWM <-----> Driver TTL

PSU V+ <------> Driver V+

Re: Marlin firmware as laser cutter

VDX — Mon, 18 Jan 2016 11:26:33 -0500

... the GND of the PSU and the Arduino has to be connected too to get the same potential ...

Re: Marlin firmware as laser cutter

jeyton — Mon, 18 Jan 2016 11:07:55 -0500

Ok, so forgive my ignorance yet again..

GND <----> PSU GND
TTL <-----> PWM pin arduino
V+ <----> PSU v+

Does the ground not need to be connected to any GND pins on the arduino itself?

Re: Marlin firmware as laser cutter

o_lampe — Mon, 18 Jan 2016 00:30:17 -0500

You can use constant power PSU for the laser. The function of the relay is the TTL input.

Re: Marlin firmware as laser cutter

jeyton — Sun, 17 Jan 2016 15:59:29 -0500

Ok... just when I start to understand something I get lost again... Based on all of this I will need to use an external power source, which makes me believe I will need to use a relay. I've been doing a lot of googling and either I don't understand enough to know what to search for or I am just not understanding this. How do I control the lasers power?

Re: Marlin firmware as laser cutter

VDX — Sat, 16 Jan 2016 12:51:28 -0500

... when power-on or reset, the Wattuino (Arduino Pro clone) in the laserdriver reads the analoge voltage at A0 (which I'm presetting with a precision pot between 0 - 5V) and sets the pulse time respective to a value of 1 to 300 microseconds (1 microsecond will in reality give 5 microseconds with this arduino).

Then with every received trigger pulse generates an interrupt, which sets the LaserON for the predefined pulse time and waits for the next trigger.

I could set this value per software per serial port too, but then I'll eventually interfere with the trigger/interrupt timing, so some trigger pulses can get lost while checking for the serial buffer ... so I've designed this 'dumb' methode with setting an analogue voltage and reset the Wattuino to restart with new values and only react to trigger pulses without any external interfering.

With my setup at home it's enough to change the analoge voltage (per potentiometer setting) manually, but in the comercial systems, I've built in the last two years, I've made this with a DAC port and relay switch connected to the reset pin of the board - so changing the max. power can be done with software -- simply set the DAC value to the wished power level, then activate the relay, deactivate it again (to release the "reset-button") and wait 2 seconds, so the Wattuino is ready again ...

Re: Marlin firmware as laser cutter

o_lampe — Sat, 16 Jan 2016 03:28:52 -0500

For realistic grayscale you have to spread the PWM evenly to a useful range suitable for your Laser. You can't just limit the max PWM.

There is not much data about the LD drivers, but in one case I saw a max. TTL frequency of 10kHz. That would match the PWM frequency of an ATMega 2560 in FAST_PWM mode pretty well.
I'll see if I can find data about the chip on my driver.

@Viktor
You pre adjust the pulse width and then use TTL to control the output power at a given point?
I also thought of using a programmable digital potmeter ( like Duet boards have for their stepper drivers ) to adjust current via software/gcode.
Have you seen that anywhere?
-Olaf

Re: Marlin firmware as laser cutter

VDX — Fri, 15 Jan 2016 13:44:20 -0500

... first, 1.8A for the 2W-diode is above the max. spec of the vendor! - her rates max. 1.7A and I'm driving them with 1.5A to 1.6A max. to get longer lifetimes.

Second - the +5V from the servo-pins are not enough and when drawn more current than some hundred Milliamperes, it will burn the voltage regulator on the board -- better use an external PS with 12V@2A.

Controlling the driver with the PWM frequency is not so usefull - the frequenzies are pretty low and the pulse-ON-time too long for proper power adjusting.

For engraving I'm driving them with pulse ON times of around 1µs to 30µs, for cutting 50 - 300µs and for engraving with 'frequenzies' (more ON/OFF timing proportions for averaging the power) of up to 300kHz!

Re: Marlin firmware as laser cutter

jeyton — Fri, 15 Jan 2016 12:26:18 -0500

Correct the Driver is not current adjustable, but I did get confirmation from the seller on which driver to get for the diode and confirmed it is TTL after removal of a 10Kohm resistor next to the v+ pad. I may have to purchase another driver though if the 1.8a driver is too much for the feed rate. It sounds like the laser may need an external power source? Or is the +5v from the servo pin enough?

In thinking about this more, couldn't the "overburn" issue be corrected via PWM instead of dropping the amperage on the driver? Change the D4 pin to not output past 200 or so for example?

Re: Marlin firmware as laser cutter

o_lampe — Fri, 15 Jan 2016 03:39:09 -0500

The X-drive you linked to, is not identic to the TTL-version the page shows at the bottom. I'd contact the seller before you buy something wrong.

I also miss the potmeter to adjust your own current-max.
The M140 is pretty powerful. I had to reduce current to 1A or even lower, because my atmega 8bit CPU ( or the SD-card? ) isn't fast enough to engrave grayscale images with more than 900mm/min.
So the only way to make it look nice is to reduce current.

I'm using one of these drivers.

IMHO the multi-turn potmeter is a must to finetune current and it is self locking too. The second potmeter to reduce max LD voltage saved a few of my red DVD-LDs.

*added image of servo header

Re: Marlin firmware as laser cutter

jeyton — Thu, 14 Jan 2016 13:06:26 -0500

Quote
o_lampe
#if MB(RAMPS_13_EFB) || MB(RAMPS_13_EFF) || MB(AZTEEG_X3) || MB(AZTEEG_X3_PRO)
    #define FAN_PIN            6 // was D9
  #else
    #define FAN_PIN            4 // IO pin. Buffer needed
  #endif
If you want to use M106/M107 commands with a 5V signal level, search Marlins code for "EFB" in all tabs until you find this piece of code in pins.h.
Change it to any servo pin you like ( mine is at pin 4 ) and connect it to the TTL input.

I also defined
// Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
//#define FAST_PWM_FAN
in configuration.h to get smoother grayscale results.

Be aware that with red DVD LDs, grayscaling is almost impossible. ( at least on light colored surfaces )
Maybe if you find a program that allows to scale the PWM between user-selectable XXX-YYY instead of 000-255. ( I'm working on rewriting "305 Engineering"s inkscape extension. )
-Olaf

This is much appreciated thank you. I just knuckled down and bought a M160 2W diode, housing, glass lense, and driver. If I am understanding correctly I want to connect my driver to the servo pins. Orienting the RAMPS power block to the left, the servo pins would be as follows from bottom up: GRND, +5v, VCC (D11,D4,D5, or D6). If this is correct then I want to connect the driver ground and power to the appropriate pins and then connect the TTL to the VCC pin is that right?

Re: Marlin firmware as laser cutter

o_lampe — Thu, 14 Jan 2016 03:37:45 -0500

Quote

I presume anyone who has this working is using an adjustable current TTL enabled laser diode driver am I right? That would allow using the D9 block to power the laser. I also presume with such driver the voltage of D9 being higher than whats typically recommended isn't too big of a problem as long as you have proper cooling on the driver and diode right?

If the TTL input is in fact a MOSFET, you can probably use a higher voltage than 5V.

You can't switch the whole driver ON/OFF with such a fast PWM, because they often have a softstart behavior.
-Olaf

Re: Marlin firmware as laser cutter

o_lampe — Thu, 14 Jan 2016 03:26:29 -0500

#if MB(RAMPS_13_EFB) || MB(RAMPS_13_EFF) || MB(AZTEEG_X3) || MB(AZTEEG_X3_PRO)
    #define FAN_PIN            6 // was D9
  #else
    #define FAN_PIN            4 // IO pin. Buffer needed
  #endif

If you want to use M106/M107 commands with a 5V signal level, search Marlins code for "EFB" in all tabs until you find this piece of code in pins.h.
Change it to any servo pin you like ( mine is at pin 4 ) and connect it to the TTL input.

I also defined

// Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
//#define FAST_PWM_FAN

in configuration.h to get smoother grayscale results.

Be aware that with red DVD LDs, grayscaling is almost impossible. ( at least on light colored surfaces )
Maybe if you find a program that allows to scale the PWM between user-selectable XXX-YYY instead of 000-255. ( I'm working on rewriting "305 Engineering"s inkscape extension. )
-Olaf

Re: Marlin firmware as laser cutter

jeyton — Wed, 13 Jan 2016 22:42:19 -0500

You're right, I just checked and its output is 4.95v, which the laser seems to work best with around 5.25v. Also I presume the voltage from that servo pin is coming from the arduino's power supply ( USB ). This explains why the laser cuts (ok), using the 5v 600mA Wal-Wort from Aixiz but NOT using D6. Still searching for the answer to this...

Also, I meant M42 not M24, sorry...

I presume anyone who has this working is using an adjustable current TTL enabled laser diode driver am I right? That would allow using the D9 block to power the laser. I also presume with such driver the voltage of D9 being higher than whats typically recommended isn't too big of a problem as long as you have proper cooling on the driver and diode right?

Would this driver work well? Aixiz Driver

Re: Marlin firmware as laser cutter

blabbersnitch — Wed, 13 Jan 2016 21:47:43 -0500

On first read of your email, I thought 'Hooray, you got it to work, well done!'. You found a way. Don't worry about D9, you don't need it now. As far as PWM goes, those outputs pulse at 500Hz. That's too fast for dithering anyway. I think you will need to do the dithering in your g-code. I generally just have it all on or all off. There have been some occasions i have used the PWM at a lower output, and that was to create a weak dot (too weak to burn) so that I could centre my piece accurately using the initial laser position as a reference. I have a grid marked out on my bed which is what I usually use to position pieces, but on the odd occasion I need to be more accurate, I use the laser on a low PWM setting.

But when I read you post a second time, it occurred to me that servo controllers output quite low duty cycles. I am not sure how the D6 output pin works, but even when a servo motor is told to move the maximum angle, the duty cycle is far below 100%. What output voltage do you measure from that pin.
And when I check M24, it tells me it is the g-code for writing to the SD card. Did you mean M280?

And again, what do you measure at D9 when you command M106 S255 with the laser driver disconnected?

Re: Marlin firmware as laser cutter

VDX — Wed, 13 Jan 2016 19:33:44 -0500

... what input type is your laser driver?

Common laser drivers have either a TTL input, which needs defined voltages in the ranges of 0V to 0.7V for LOW, and mostly +2.5V to +5V for HIGH.

- or they have an analog input, which can be driven with an analogue voltage between 0V to 5V - here the output power is related to the voltage.

But an analog input will behave identical to a TTL, when driven with only 0V/GND or +5V signals ...

Re: Marlin firmware as laser cutter

jeyton — Wed, 13 Jan 2016 19:01:57 -0500

My driver does not have TTL, however I am using the Servo pin D6 and using M24 P6 S255 to turn the laser on and off right now, I would like PWM for better control of the laser eventually to allow for Rastering/Dithering. Still not following how to make that work with D9 block.

Re: Marlin firmware as laser cutter

VDX — Wed, 13 Jan 2016 18:31:04 -0500

... if the driver has a TTL input, then it's meant for 5V input -- any voltage above 6Volts will (or already have) destroy the input electronics of the driver !!!

Re: Marlin firmware as laser cutter

blabbersnitch — Wed, 13 Jan 2016 17:44:02 -0500

A multimeter will read average voltage. It doesn't matter if it's PWM. Make sure you have it set on DC Volts. The pulses are 12V. With the S255 setting you are using, the pulse width is 100% and the output just looks like a steady 12V DC. And with S128 (for example), each pulse will be at 50% duty cycle (the pulse would go for 1msec, and repeat every 2msec). The multimeter will read the average, i.e. 6V (or thereabouts).

If you want to know if the D9 output is working, try measuring it with the laser driver disconnected.

With S0 and S255 you are basically switching 12V to the driver. Do you have any info on the driver? What supply it requires?

I just had a look at the RAMPS and Arduino schematics, it all looks to be 5V.

Re: Marlin firmware as laser cutter

VDX — Wed, 13 Jan 2016 17:19:59 -0500

... caution! -- the MOSFET's will switch your PS-voltage, what's 12V (or 24V if supplied with), what will damage any TTL input!

I don't know exactly, if the Arduino 2560 has 5V or 3.3V digital output - if 5V, then you can wire one of the sparse digital I/O-pins directly to your TTL-input and GND of the RAMPS to the GND of the laser driver.

If 3.3V, then you'll need a 5V voltage driver -- e.g. a 7805 voltage regulator, to get 5V from the 12V, and a transistor for switching the 5V to the TTL input ...

Re: Marlin firmware as laser cutter

jeyton — Wed, 13 Jan 2016 17:03:05 -0500

Yes I do:
// The following define selects which electronics board you have.
// Please choose the name from boards.h that matches your setup
#ifndef MOTHERBOARD
#define MOTHERBOARD BOARD_RAMPS_13_EFB
#endif

I do get voltage out from D9 when I turn it on, my multimeter shows it at 1.5v but I presume thats because its PWM and my meter is not an oscillator. It seems I need to do something with TTL which my laser driver doesn't have. I am a bit lost on how to wire it to the RAMPS even if I did have a TTL pin on my driver.

Re: Marlin firmware as laser cutter

blabbersnitch — Wed, 13 Jan 2016 16:15:03 -0500

As Viktor said, it's a PWM output. So at max output, you should be measuring around 12Vdc. My laser is 200-300W and I have no problem driving it. Do you get anything at D9 with the laser driver disconnected?
Have you set the motherboard type to 'EFB' in the configuration.h file? With no 'F' in the middle, M106 will not do anything (M106 drives the fan output, the 'F' in EFB tells Marlin a fan is connected).

Re: Marlin firmware as laser cutter

jeyton — Wed, 13 Jan 2016 15:42:26 -0500

Quote
VDX
... AFAIK the fan output is a PWM signal, so with a multimeter you'll see the averaged voltage only.

You need an oszilloscope to see/measure the exact timings and voltage levels ...

Interesting... I am still pretty new to all this so forgive me. Just to confirm the standard Output of the D9 block on RAMPs 1.4 is sufficient as the laser power source, assuming a 200-500mW laser?

*update* I just tried the laser on D9 and it did not power, even manually setting M106 S255

Re: Marlin firmware as laser cutter

VDX — Wed, 13 Jan 2016 13:37:23 -0500

... AFAIK the fan output is a PWM signal, so with a multimeter you'll see the averaged voltage only.

You need an oszilloscope to see/measure the exact timings and voltage levels ...