Hey everyone- I've been working with Arduinos and Pi's for a few years, but now I'm using a stepper for the first time and am getting confused.
I'm trying to get a NEMA 17 stepper motor to run with a Cytron MDD3A (3 amp) driver on a Nano. When I first hooked it up with lightweight jumpers to test it using Tom Igoe's stepper_OneRevolution lib, it ran, though the 200 steps programmed only turned the motor about a third of a revolution. The jumpers from the 12V power supply got hot if I ran it too much longer, so I changed the leads from the power supply up to 16ga wires. Right away, it changed: now the stepper just clicks, and the spindle seems to just wobble in place; no advancing. I switched back, just to prove to myself that it really was running before, and sure enough, it did, hot jumpers and all.
I've confirmed that the stepper is a 1.8 degree (200 step) motor. Checked continuity and voltage everywhere, and it all seems right. Wired up like the attached fritz pic.
But not getting a full revolution with 200 steps, combined with the weird wire problem, has me stumped.
Please display your image(s) in your post so we can see it(them) without downloading it(them). See this Simple Image Guide
Please post a link to the datasheet for your stepper motor. Nema 17 just tells us the size of the front face - 1.7 inches.
It is almost certain that your motor needs a specialized stepper motor driver rather than a h-bridge. But without seeing the motor datasheet it is impossible to suggest anything.
mbewley59:
Hey everyone- I've been working with Arduinos and Pi's for a few years, but now I'm using a stepper for the first time and am getting confused.
I'm trying to get a NEMA 17 stepper motor to run with a Cytron MDD3A (3 amp) driver on a Nano. When I first hooked it up with lightweight jumpers to test it using Tom Igoe's stepper_OneRevolution lib, it ran, though the 200 steps programmed only turned the motor about a third of a revolution. The jumpers from the 12V power supply got hot if I ran it too much longer, so I changed the leads from the power supply up to 16ga wires. Right away, it changed: now the stepper just clicks, and the spindle seems to just wobble in place; no advancing. I switched back, just to prove to myself that it really was running before, and sure enough, it did, hot jumpers and all.
I've confirmed that the stepper is a 1.8 degree (200 step) motor. Checked continuity and voltage everywhere, and it all seems right. Wired up like the attached fritz pic.
But not getting a full revolution with 200 steps, combined with the weird wire problem, has me stumped.
Any ideas?
I Googled your driver board, Cytron MDD3A, and can find no hint that it can be used with stepper motors. What am I missing?
That stepper motor requires 2 amps per coil so it will definitely need a specialized stepper motor driver. I would choose one that can provide at least 3 amps - which probably means a driver that uses the TB65xx or TB66xx chip
Stepper motor drivers are designed to be able to limit the current to protect the motor so you can power the motor with a high voltage without damaging it.
The image beneath your caption "Here the layout:" is completely inappropriate for the motor in your datasheet. The small 28BYJ-48 stepper motors are unipolaar motors with 5 connections.
Robin, thanks- here's something I drew in Sketchup that accurately represents my wiring and the driver board. The MDD3A driver is rated at 3 amps continuous current.
The MDD3A driver is rated at 3 amps continuous current.
That is not a stepper driver.
You need a current limiting stepper driver rated for more than 2 Amperes or plan on limiting the motor current to 1.5A or less per winding, and use a driver like this one.
Okay, so the manufacturer just misrepresented it as a stepper driver. Shocking. Thanks for that, jremington. And it's the only thing that makes any sense out of what I've been experiencing.
Think I'll go look at the Pololu TB65, TB66 drivers.
So what? Do you not understand that 2 Amps per winding is simply the absolute maximum continuous current rating?
@OP:
Okay, so the manufacturer just misrepresented it as a stepper driver.
Yes and no. Some high impedance bipolar stepper motors can be used with that brushed DC motor driver, but the low impedance motor you have cannot. It requires a current limiting driver.
You can always drive a stepper motor with less current than the absolute maximum, you simply get proportionally less than the specified maximum torque (and save on power, of course).
mbewley59:
Okay, so the manufacturer just misrepresented it as a stepper driver. Shocking.
You can drive a high-impedance (20 to 60 ohms) stepper from a dual H-bridge, with constant voltage drive, but it will
go only slowly.
These days the vast majority of steppers are low impedance (0.5 -- 2 ohms), which require current drive, not
voltage drive, and can spin much faster (limited only by supply voltage). Your motor is 1.4 ohms, completely incompatible with 12V voltage drive.
Thanks for that, jremington. And it's the only thing that makes any sense out of what I've been experiencing.
Think I'll go look at the Pololu TB65, TB66 drivers.
