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Author Topic: Controlling micro servo with Mach3  (Read 250 times)

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Offline JVG

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Controlling micro servo with Mach3
« on: July 03, 2021, 01:47:59 AM »
I want to control a Tower Pro SG90 micro servo using Mach3.  Before I dive in and start experimenting I thought I'd reach out and see if anyone has done it or has an idea how to do it.  I'm thinking it might be as simple as using the Mach3 spindle controls and just connect the signal terminal for the servo to the step pin of the controller (like a Gecko G-320x).  Anyway, any insights would be appreciated.

Offline Tweakie.CNC

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Re: Controlling micro servo with Mach3
« Reply #1 on: July 03, 2021, 03:47:54 AM »
Model control servo’s require a specialist type of PWM signal ranging from 1mS to 2mS repeated in a 20mS loop. Mach3 was not designed to produce this type of signal but it can be created from the Mach3 spindle PWM using some additional electronics.

It was many years ago I did this but you can download a short video of it in action from here;
 https://mega.nz/file/PQNi0BwY#FfgCYPQPfs-3nl2WY_hBwoVk29elZFXzUUhsretOR5c

And there are details of how it all works here;
https://openbuilds.com/builds/software-speed-control-of-a-brushless-dc-bldc-motor-from-mach3.762/

Hope this helps you with your project.

Tweakie.
KEEP SAFE !

Offline JVG

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Re: Controlling micro servo with Mach3
« Reply #2 on: July 03, 2021, 03:36:56 PM »
Thanks Tweakie.  I've read through your documentation and I'm not too proud to admit that this is waaaay out of my wheelhouse, but It's awesome to have a solution.  I tried to follow the link embedded in your documentation for an off-the-shelf controller (http://www.logicnc.com/rcnc.html) but unfortunately it's not active.  I googled logicnc but didn't find anything.  Can you provide me with other ready-made controllers? 

Offline JVG

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Re: Controlling micro servo with Mach3
« Reply #3 on: July 03, 2021, 03:47:04 PM »
OK, I just found a couple of videos on YouTube from LogiCNC from 8 years ago, but that's all I've found....so far!  Any additional help you can provide is appreciated.

Offline Tweakie.CNC

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Re: Controlling micro servo with Mach3
« Reply #4 on: July 04, 2021, 03:12:00 AM »
Unfortunately Logicnc is long gone and I do not know of any equivalent product.

It’s a step learning curve but Mach3 can send serial information or it can (using VB code to call a batch file) write directly to USB devices connected to the PC.
I don’t know of anyone else that has done it so you may be on your own with this but the Pololu Maestro USB servo controller may well perform the task you require (assuming it’s HID compatability).
https://www.pololu.com/docs/0J40

I have, in the past, used HID USB connected relays with Mach3 so I know the Mach3 USB communication is sound. https://www.machsupport.com/forum/index.php?topic=42968.0


Tweakie.

KEEP SAFE !

Offline JVG

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Re: Controlling micro servo with Mach3
« Reply #5 on: July 06, 2021, 02:39:04 PM »
Again, thanks a ton for your responses, insights and recommendations.