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Topic: NEMA 17 stepper with L298N controller turning on and off constantly when in use (Read 509 times) previous topic - next topic

plumbo20

I am powering a NEMA 17 stepper motor using an L298N motor controller and an Arduinio (replica) Mega board, that I know works just fine. When the stepper_oneRevolution code is run the result is not turning once in each direction constantly, but rather the whole system turns on and off every half second or so. When a significantly under-powered power source is used, I can hear the stepper trying to make the correct rotations, and neither board turns off at all. But, when I hook up my usual 12V 3A max power supply I get this cyclical turning on and off. I suspect the issue is that 36W must be too much for the L298N, but can it really not handle this??? I ran it with a 14V 2.4A supply and it worked properly, but the MOSFET got very hot, very quickly. I want to know if I absolutely must purchase a new, lower power, 12V supply before I buy one, if this is the cause of the issue. Thanks!

Robin2

An L298 is a very poor choice for driving a stepper motor.

You need to post a link to the datasheet for your stepper motor - Nema 17 just tells us that the front face is 1.7inches across.

My guess is that you are overloading the L298 and it is cutting out to protect itself.

Have a look at these links
Stepper Motor Basics
Simple Stepper Code

...R
Two or three hours spent thinking and reading documentation solves most programming problems.

plumbo20

What makes it a poor choice? (I'm not arguing, I really don't know)

I too suspect that it is cutting out to protect itself, this is as much info as I have on it:

https://www.ebay.co.uk/itm/3PCS-45Ncm-Nema-17-Stepper-Motor-2A-4-wire-1m-Cable-for-DIY-3D-Printer-CNC-Robot/121693581331?hash=item1c5580b013:g:ikgAAOSwHnFVioYU

What motor driver would you recommend as an alternative, are there options that will let me keep using the 36w supply?

jremington

Quote
What makes it a poor choice?
The L298 is ancient, extremely inefficient, and cannot handle the current required by most stepper motors.

The link you posted in reply #2 states that the motor is rated for 2A/winding, and to get the full rated torque, you will need a commercial stepping motor driver.

Why did you choose that particular motor?

Robin2

What makes it a poor choice?
As well as what @jremington has said an L298 does not have the ability to limit the current in the stepper motor for every step and that is essential if the motor is to use a high voltage power supply. Stepper motors work better with high voltages

Quote
What motor driver would you recommend as an alternative, are there options that will let me keep using the 36w supply?
For a 2 amp motor I would choose a stepper driver that can handle at least 3 amps - which rules out the A4988 and DRV8825 drivers such as are sold by Pololu. A driver that uses a TB66xx or TB65xx chip will probably be the cheapest.

Your 12v 3A power supply should be fine - unless the driver has a higher minimum voltage. Some of them have an 18v minimum.

...R
Two or three hours spent thinking and reading documentation solves most programming problems.


MarkT

What makes it a poor choice? (I'm not arguing, I really don't know)

Its not a stepper driver.  Steppers use constant-current drive.

Its a DC motor driver.  DC motors use voltage drive.

Your stepper wants 2A.  The voltage it needs depends on many things, but mainly motor speed.
Constant current chopper drivers for stepper motors do just what is needed (within the limits of
the power supply) to provide the correct current.

Some high-impedance steppers can be driven constant voltage, but yours isn't such a motor, and
such motors cannot go fast.
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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