Hi all, I was wondering if it would be possible to use the TB6612FNG board SparkFun Motor Driver - Dual TB6612FNG (1A) - ROB-14451 - SparkFun Electronics to control a stepper motor, for example one like this one Stepper Motor - 68 oz.in (400 steps/rev) - ROB-10846 - SparkFun Electronics I realize I would have to write some code to do this, but as a software guy I'm a bit lost on the hardware aspect. Thanks.
You have a high-performance bipolar motor there - 1.7A is asking a lot from any single-chip DMOS driver,
so good cooling will be essential.
Also you'd get much better performance with a chopper drive IC designed for bipolar motors and a high
voltage supply (especially for that motor, as is 0.9 degree steps). Do you have speed requirements more than
100rpm?
Speed isn't crucial as much as torque is. I want to build a CNC like machine with several of these. Perhaps one of these instead? Pololu - Stepper Motor Drivers
belt or leadscrew? If leadscrew then you want high speed, trust me...
The stepper mentioned is rated at 3v/1.7A. In other words a 2ohm coil ! Can someone explain to me the reason for such a low coil resistance. Hi speed? Hi torque?
I have used small steppers in robots but am not experienced with the steppers used in CNC.
I certainly agree that a true stepper driver will give better performance.
I was looking at a lead screw design for precision... So high speed it is? Something that can provide more amps is necessary then?
Low impedance windings have low inductance - this allows the current in the winding to change
fast enough (remember a 1.5A stepper motor going at 2000rpm requires current to change from
zero to full and back again every 150us!!!, which at 5V would need windings with less than 0.5mH
inductance. Even a 2-ohm motor will have more like 2--3mH inductance, necessitating a supply of
at least 30V and chopper drive of 20kHz or more. Also the back-EMF from motor rotation at high speed
will require a high voltage supply to overcome.
That same 2 ohm motor would only get to about 300 rpm at 5V, and if it had 20mH windings then
you'd struggle to get above 60rpm.
Really high performance steppers are usually 3 to 5A, 0.3 to 0.6 ohm, and driven from 80 to 120V
supply via discrete MOSFET bridge chopper circuits. Beyond that high performance servos with
high-resolution encoders are used.
For a leadscrew you will want more like 1000rpm than 200rpm, or its really really slow rapids...
(large pitch multi-thread ballscrews will help a lot, not cheap though).