I have a TinyG v8 on an SO2 CNC. When I bought the TinyG I bought it explicitly for the advertised of 6-axis support. I currently am using the 4 on-board drivers to run the SO2 since the Y-axis runs on 2 motors. I don’t want to double up 2 NEMA23 motors onto a single driver. I now will finally be adding a rotary.
How do I add external drivers for the 5th motor? I have a handful of A4988 drivers on hand already but not finding a means to wire them in.
Thanks.
Or could I theoretically add an external driver to motor 3 and use both the on-board and external drivers for the Y-axis dual motor setup and then dedicate motor 4 to the rotary?
As you said: I would take the machine config back down to simple XYZ and A for the 4 on-board motor drivers. Use the 4 pin take-off header to get step / direction / enable for the Y axis to an external driver to double up the Y.
If your Y axis is set up like most dual Y machines the 2 Y axis motors will need to be opposing polarity, which you can do in HW just be reversing one of the two stepper output pairs.
@Alden_Hart Is there anything special I need to do in the config for the take-off header to drive the external driver? Or are they just electrically coupled and whatever goes to one will go to the other?
I figured I"d have to flip polarity on the hardware side. I need to figure out how to actually power and drive external drivers as well I guess. I just have a bunch of stepstick daughter board style drivers.
Thanks
The take-off outputs are literally the same step, direction and enable signals that are going to the stepper driver they are aligned with. They are 3.3v level, coming right off the MCU. You do not need to do anything in the config. Good luck - please let me know how it goes.
Ok, on the TinyG I have Step, Direction, Ground and Enable. On my driver I’m using (switched to a probotix side step for ease of wiring) I have Step, Dir, +5v, NC and Gnd.
Step, Dir and Gnd are self explanatory. But what is Enable compared to +5v and NC on the driver?
Any thoughts?
My gut says to use the NC since Enable is active low 5v would be wrong, but I’m not 100% certain.
It sounds like the external driver is permanently enabled, and probably wants 5v inputs. In most cases 3.3v inputs are sufficient to drive a 5v system. Of course, wiring 5v into a 3.3v input can destroy it. But that should not be the case here. I would try wiring the step, dir and GNC. Leave the other 2 floating.
Do you have a spec for the external driver? Is it not this one:
http://reprap.org/wiki/StepStick
If so, you have the enable line, and you will need to set the microsteps to the same value you have configured the motor to (probably 1/8)
http://reprap.org/wiki/StepStick
I have 2 different drivers. I was going to attempt to use this one since it was next to me at the time: https://www.probotix.com/manuals/SideStep.pdf
However I do have several A4988 like you linked that I can use I’ll just have to get some JST connectors or a socket of some sorts to wire it up which I don’t have on hand. Or just breadboard it
The probotix does not have an enable. So wiring the step, direction and ground should suffice. It says it will work with 3v logic, so that’s good. Do not connect the 5v line to anything. It would only blow up your Tinyg. NC is no connect, so it does nothing. Don’t connect it, either.
First test didn’t go so well. Any time I plug in the external driver to the tinyg it basically shuts down all activity on that set of motors. If I unplug the external driver it frees up and the one motor turns as expected. Going to try with the stepstick