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EternalTinkerer
MemberNo worries, I appreciate you taking the time to chime in!
On my v8 board there spots to solder on headers for the Enable, Direction and Step signals for each stepper. I gather from the wiki and various forum posts that they are intended to be used with external stepper drivers, in case you want to use more powerful steppers than the driver on the TinyG will allow. I am hoping to use the direction signal from my Z axis stepper driver on the TinyG to control the laser turning on an off. Z axis moves up, laser goes off. Z axis moves down, laser goes on.
But I may have answered my own question, at least with regards to the transistor. If I use a MOSFET, they are voltage driven, not so much current, so I don’t think I need to know the exact current rating of the pin. An N-channel MOSFET like this one for example http://www.adafruit.com/products/355 can apparently switch off of a 3.3V signal and switch up to 30V@60A which is more than plenty for my application.
Well, back to Google to see what else I can come up with 🙂
MemberYes, it is indeed the v8, sorry for the oversight.
I did find that diagram, but I was hoping for something a little more detailed.
Here’s a little info on my planned project, perhaps that will give an idea of what I need.
I preordered the Shapeoko 2 mechanical kit and am planning on making a semi-portable laser cutter. Well, laser etcher is probably more accurate for now as I only have a 1.5W 445nm laser currently. I have a Raspberry Pi and a TinyG v8 for control and they will be put in a small case and mounted on the Shapeoko somewhere.
One of the difficulties is control of the laser on/off and there are lots of solutions out there, but it occurred to me I could simply take the Z-direction output signal from the TinyG breakout header and feed that into a transistor, used as a switch, to switch the laser power on and off. The idea being I can generate gcode as usual, but just make sure the Z-axis travel for rapids etc is a very small amount, 0.01″ or so, so the laser stays in focus, but also moves just enough to get the direction pin to change from 0V to 3.3V and vice versa.
My laser driver will use 24V @ 1.8A (though I may drop that to 12v @ 1.8A if heat becomes an issue) and I was wondering what the Z-direction signal is so I can pick a transistor appropriately. It is 3.3v I believe, but what’s the mA output?
So all I need for now is that one little bit of info, but the more info I can collect, the more possibilities open up for future projects 🙂 I could also be barking up the wrong tree with my idea, but if it works as I envision, it would be a nice simple solution.
If I need to clarify anything, please let me know.
Thanks! -
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