Run external Stepper driver with Duet PWM signal
-
Since setting up a "Continuous rotational axis" is not yet supported by RRF, I thought about a workaround to get a continuous rotational axis that won't interfere with the rest of the movement system...
To recap:
I use a stepper motor peristaltic pump on my CNC-Router to control the coolant flow while milling aluminum parts. My original Idea was to set up an extra Axis on the duet to control the stepper motor of the peristaltic pump. Right now this doesn't work since there is no option to run an axis continuously and progressing the axis in a loop would block other movements.Here is my Idea:
So I need a stepper motor that can basically be controlled like a Fan in DWC. So why not use one of the duet's PWM outputs to generate the step pulses for an external Stepper motor Driver? -
undefined MaxGyver marked this topic as a question
-
@MaxGyver I'd guess that could work. Set up a PWM pin as either an output (M42 controlled) or fan (M106 controlled) with M950. Set the PWM duty cycle to 50 percent (either with M42 or M106), then adjust the PWM frequency (M950 Q parameter) to get the speed you want. You may not even need to provide a direction or enable signal. Remember most drivers need 3.3 to 5V signal, so don't use a fan output unless it's supplying that!
Ian
-
A more dodegy approach would be, to physically attach a speed potentiometer of a stepper driver circuit to a small hobby servo motor, the servo motor could than turn the speed of the stepper motor / peristslt pump, it's a bit dodgy but it works, I have done it before..
