Need advise on a laser setup

I do not think that will work. The 12v ports should always be grounded and the + will be mosfet switched. You should have a few extra 5V capable pins, servos pins, something on your board.

Sorry, Ryan, but at least for ramps your expectation is not true:

[attachment file=“RAMPS1_4schematic.png”]

Honestly i’m also not fully right - it connected to 12v by led+resistor (they can be cutted)

No, i didn’t say to connect “+” wire of the d9 connector to somewhere. Especially don’t connect it directly to +5v, you may damage the board.

You need “-” wire and ensure woth tester that it not has indirectly +12v via a “led+resistor” on the board (like ramps has). 12v here may damage laser control board

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Yes thank you for the clarification. That is what I meant but my words were not very clear. Connect the - pin from heater 1 to the resistor and then that goes to the laser - TTL.

Then then the + TTL from the laser goes to a +5 v elsewhere on the board.

The heater + 12 V is not used at all.

Ryan - This is from years ago in my ITT-Tech classes for Electrical Engineering. (A degree I never used except as a hobby) My Professor explained how most ICU (Integrated Circuits or Chips) are designed to handle more of a load through the negative pin than they are the positive or logic pins. So you could draw more current through the chip if you use a positive source and then use the logic chip as your ground. Instead of trying to push a positive voltage through a logic chip and have that connect to a negative source.

My memory could be wrong but I do know that I have seen consumer electronic circuits that are built to have logic control the negative pins more often than I have seen the positive pins. So counter intuitive. I will check my board. It will be easy to check. Just use an Ohm meter between the heater - pin and - pin from the 12v power supply. If that is an open connection then you know logic on the board is wired up to control - pin. If it is close to 0 then the board is probably wired to control the + pin. In which case i will need to figure out a voltage divider as well.

A voltage divider did not work a few years back when we tried, it is much easier you just have to figure out what pin to use for 5V, It is even built into marlin now. I have never used or seen your board so I can’t really help, but just find a 5V capable pin. Doing it the right way is actually the best way.

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I’d try to use A11 r A12 on that board, they should be 0-5V outputs, driven using the matching +5V and Gnd pins. That’s on connector XS3. If that isn’t going to work I’d switch to connector XS6 and use the digital outputs there, D50, D51 et al.

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A11/12 haven’t hardware PWM
By the way, if your mks base is modern you will see that in reality it can be a bit different then layout picture of v1.1. It has pins for D11, D12 (it doesn’t help you because both of them have hardware PWM, but used by ISR)

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How about D50/D51 et al?

Holy cow, learn something new everyday! Thanks for the schematic, I had seen it a million times and never realized it was +switched. That explains a lot.

http://marlinfw.org/docs/configuration/laser_spindle.html

Yeah, but that page doesn’t help much with a MKS base v1.1 board…

Guffy you are brilliant! Thank you for the help. Your initial post suggesting I use pin 9 will most likely work. I made a mistake when I looked up pin 9 on my board pin diagram pictured previously. I thought that was the heater and I said that in my replies. Since pin 9 is the fan that means I don’t have to make any firmware changes. I just use M106/M107 like you said.

I checked last night and my board does indeed use mosfet to ground so I can use the ground pin from the fan and a +5 from somewhere else. Probably XS3 like Bill suggested. I tested with a volt meter from the source +12 to the fan - and it was 0 potential. I set the fan speed to 100% (M106) and it showed 12v. Conversely when I tested the source - to the fan +12 it was always +12v regardless of fan speed settings.

Last night I looked up how a pullup resistor works. In detail it seems complicated but I can simplify it very easily in the picture. Please correct me if I am wrong. I want the TTL to have a constant plus 5V on the + pin. I want the Negative pin on the TTL to also be +5 V (Through the pullup resistor) until I want the laser to be on. That way it will have 0 V potential between the two TTL pins. Then when I send M106 pin 9 on my board will go from open to ground. That will cause a 5v potential across the TTL pins. Some power will go straight through the pullup resistor from +5 to ground but not enough to cause a short. (I will start with a 10K resistor.) Here is a picture of what I will wire up tonight.

[attachment file=“TTL Wireing.png”]

This way I get my 5V pwm and avoid the voltage dividers Ryan said were unusable.

Guffy that link that you provided was incredible. http://marlinfw.org/docs/configuration/laser_spindle.html It helped to show all the pwm enabled pins which is what I really needed to confirm the fan pin would work.

Thank you for the suggestions Bill. Since none of those pins are pwm enabled according the list in the link I don’t think they would work but I really have to wonder if the analog pins A11 and A12 could still somehow be used with the laser driver I have. Because I can flip a switch and have it go from TTL to analog. In any case I have no clue how to do that and I now have enough of an understanding that I think TTL is the way to go.

Thank you. I am 100% sure my board in the older version 1.2 from the previous picture. Old board but still usable. So I am convinced I can use the fan pin 9. I may try to play with the firmware later to see if I can use one of the heater pin sets to power another 12 V fan using the M106 P1. But not tonight.

[attachment file=80021]

So I will be trying to wire this up tonight and get it running. If I let the magic smoke out I will inform everyone that I am once again wrong in my understanding of how things should work. Thank you everyone for the help. I am truly grateful. Cross your fingers because I am gonna try to burn stuff.

 

 

 

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i guess most boards have it because it most simple and obvious way

it seems the board hasn’t leds between +12 and mosfet. anyway disconnect fan and ensure that there is no +12V between ground and ‘-’ pin of the connector.

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It works! It works perfectly! Oh snap! That’s amazing!

by the way. i have seen sample how to make a module for smoothie. it shows how to write laser controller:
http://smoothieware.org/moduleexample
and in that example they show how to control laser power depend on feedrate.
marlin hasn’t such code even in “official” M3 laser implementation.
and of course with M106 you will have constant power not depended on speed. this task should be solved by software that produces engraving gcode. i hope it could

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So I’m working with George Formatchev with Endurance to buy a 10+ watt kit… He’s really got them dialed in now with advanced heat sinking and his Laser Box has all necessary gauges to monitor voltage, current and heat. He’s also about to release the 10W Infra Red laser… which should be the BOMB as it’s safer (in a way) and has a smaller ‘Dot’… ergo smaller and finer detailing, also less heat to light ratio.

I’m running a RAMBO board (dual endstop firmware) and Ryan has indicated to use pins 45 and 31 for the Laser control & TTL out I believe. I know Nick has spent some time with the cheapo chinesium lasers but do any of you guys have an Endurance Board and Laser? Now, we all know I’m mentally challenged (ADHD… LOOK SQUIRREL!!!) so can anyone draw a simple diagram of the hookup for the above mentioned pins? If anyone is using a RAMBO have you had success with #'s 31 & 45? If not, what pins are you using.

2nd Question: this may be hard for me… Firmware modifications to use said Pins?

Thanks Guys.

Thanks!

Have you read Ryan’s main laser page? It has most of the information you would need. Use the search feature up top and type in laser. It should be the first result.

Here are some pointers for you anyway.

As I understand from my 5.6 watt Endurance laser you will need to build your own small control circuit. This circuit will use a small breadboard that you will solder some components onto. It isn’t difficult to do. As you do this you will be connecting a 12 volt power source to you laser. This will need to be the same 12 volt power that will power your Rambo.

Next you will need to connect the laser control pins from your Rambo to the TTL on the laser. This connection is also one you will build into that circuit. Again it isn’t difficult and they will have all the instructions for you.

Here is the cool part about endurance lasers. They can accept a 5 volt or 12 volt control signal. So you can use either set of pins from your Rambo board you choose. As far as I know Endurace lasers are the only ones that can do that.

So how will you choose which set of control pins to use? I will tell you that right now you will want to use the 12 volt fan pins. And here is why. Marlin has two firmware bugs for controlling lasers at the moment. One bug is in the fan control code and the other is in the laser pin enabled code. We (Ryan) have a work around for the bug in the fan control code.

So read Ryan’s laser page and apply what I mentioned here and you should be just fine.

Aaryn… Thanks for the reply.

The endurance Laser I bought is the 10W+ model… As far as the addtl circuit Goes I think Endurance has that covered, see below. Is Ryan’s ‘laser page’ referenced here I’m not sure where it is… One of my main questions is about firmware, and so far I can’t find an answer, do you mod the MPCNC firmware or use it as is? I plan on using Lightburn sofware and of course Inkscape with the Tech Photonics plug in as well to generate my Gcode. Pretty sure either can adapt to whatever pins you choose. I don’t really understand your “Bug” sentence…

"Marlin has two firmware bugs for controlling lasers at the moment. One bug is in the fan control code and the other is in the laser pin enabled code. " huh? I thought a “bug” was a problem, so… ??

I included an image of what they’re sending me. Also Here then is a link to the sales page, scroll down and you can see the newer Laser Control box with the TTL wires. Can you post a link to “Ryan’s Laser Page” for me? I cannot for the life of me find it!

This stuff seems to go round and round and what should be simple as pie is as complicated as a greek trilogy because of all the flavors of boards, etc.

Hi Mark

here is the link to Ryan’s laser page.

I think it might be confusing to find because when you use the search feature is is difficult to tell that you are seeing links to several different pages. the first picture that comes up in the search is actually the link to the page you need.

Yes it looks like you are correct you will not need to build the circuit I mentioned earlier.

Yes. There are known bugs in the firmware. And yes that is bad. But like I mentioned before we have a workaround or solution for one of them.

I know it is a lot of information and you have direct questions. Those questions are answered in Ryan’s laser page.

To help ease your mind I will take the time to answer a few now. Yes you will need to reflash your firmware. No you wouldn’t normally need to reflash. The reason you will need to now is because of the bug that was recently found in the newer firmware versions. Ryan has a link with how he figured out how to fix the bug in the code. The fix just hasn’t been added to the firmware builds that can be downloaded yet.

Yes is it confusing. There is a lot of info and a lot of ways to get it working with lots of options. That is why I am suggesting a single path for you.

Plan on using the 12 volt fan pin as your TTL control. You can get away with that because your laser can handle the higher voltage signal.

Plan on downloading one of Ryan’s firmwares for the Rambo. Then plan on modifying the code on one page then uploading it to your board.

Then you should be able to use M106 S(0-255) for setting laser power. And M107 to turn it off. That is the same commands as turning the fan on and off.

As you get into the details ask any questions you want. It might make sense to start a new thread of your own so you can reference it easier from your profile page in the forums. Or keep asking questions here. You will get help either way.