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Topic: TTL Laser control (Read 793 times) previous topic - next topic

Ali-Kat

Apr 08, 2018, 09:22 pm Last Edit: Apr 08, 2018, 09:24 pm by Ali-Kat
Hi guys,

I'm a newbie on the forum but have been following Arduino based projects for some time now.

I recently was asked to help out setting up a laser for a fund raising group as they were aware of my CNC background. This led to me finding out a lot about Arduino control and GRBL in particular. Needless to say, it got my brain ticking and I have purchased a 15W 450nm laser module with TTL controller. Whilst it works fine when plugged in and switched on, I would like to use the TTL / PWM capability to vary outputs and bring in a low power focussing beam as required. I am not an electronic expert but i understand the principles of basic PWM and TTL control. What has stumped me is the headers on the TTL driver board for this laser.

As I hope you cam see in the photo, the input side has two sockets. The left socket has a connector to the (supplied) 12v DC PSU along with a single red wire that is just terminated with one pin in a twin socket. To the right is a two pin header which is marked -PWM/TTL+. This is also marked above the single red wire referred to earlier.

There is a latched button swith on the board which controls wether the laser is giving full power or reduced power for focussing. This is not ideal as I don't want to have to fiddle with small buttons in order to focus the beam and then have to switch off the TTL board before switching over to full power in preparation for machine moves.

Has anyone seen one of these boards before or can explain how I should be connecting this to my Uno (with CNC shield).

Thanks in advance for any help.

Ali

ReverseEMF

#1
Apr 08, 2018, 10:15 pm Last Edit: Apr 08, 2018, 10:22 pm by ReverseEMF
I can see that the "-" pins are tied together (from the photo), so, how about using an Ohmmeter (or continuity tester) to check if the two pins, both marked "PWM/TTL" are connected together, and thus are the exact same connection.
If so, then it's a fair bet that connecting the Arduino Gnd to the "-" pin on your Laser, and the "PWM/TTL" pin to one of the PWM outs on the Arduino, is the correct way to go.

Also, here's a couple of links I found that discuss this very thing:
* https://www.3dhubs.com/talk/thread/added-laser-wanhao-i3-plus-problem-pwm-ttl
* https://www.machsupport.com/forum/index.php?topic=30369.0
And I found these specs on a 15W Laser board that looks similar to yours ("open" is probably a mistranslation for "on", like the "Valve is open":
- Modulation frequency: ttl can be modulated
     0v- Off
     5v open
     Pwm frequency <9Khz


And, as for how to connect this along with the CNC Shield -- are there any Arduino pins not being used by the Shield?  Is there a diagram for that Shield available?  Looking at traces might not be enough, as there is the possibility of more than 2 layers.  Beyond that, perhaps your answer is in one of the above links or maybe someone else has more experience with this.
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mlynn

I have an interest in seeing this thread topic completed!

I have a very similar laser with TTL module and 12 volt power supply, called an ACAN-A12

I need to know how to talk to it's ttl pins from arduino safely and without destroying the laser or arduino.

Any expert advice on the matter would be greatly appreciated!

DVDdoug

Although "TTL" is a specific logic family, it's is sort-of shorthand for "5V logic" and the Arduino is TTL compatible.

So IF your laser has a TTL/PWM dimming input is should be as easy as dimming an LED.

Many (most?) laser power supplies are designed with feedback for constant-controlled light output and they are not dimmable...  They will "fight you" if you try to dim them.   

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