Problems with Stepper motor connected to v2.3 shield

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shakezoola
 
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Problems with Stepper motor connected to v2.3 shield

Post by shakezoola »

I bought a 57oz-in (1Nm) NEMA 17 12v 1.3A stepper to use with the AdaFruit v2 motor shield. But when it is connected, and I run my code, nothing happens. Below is the coil wiring privided from the manufacturer.

Bipolar
Coil 1:
Black A
Green A-

Coil 2:
Red B
Blue B-

Connected to M1-M2 in order, skipping the middle (ground).

My code works perfect with the motor I bought from Adafruit. I assume that this may be a motor wiring issue but I'm not sure. Could it be that the 1.3A motor just too much for this shield?


Thanks.

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adafruit_support_mike
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by adafruit_support_mike »

Motors don't always meet the written wiring spec, but never lie to a ohmmeter.

Check the resistance between the terminals. Bipolar motors are easy because you get all-or-nothing results. If the resistance between two wires is a few ohms, they belong to the same coil. If the resistance is infinite, they belong to different coils.

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shakezoola
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by shakezoola »

I measured the resistance of my motor, and it confirmed that the coil pairs are black/green and red/blue.

------------Black--------Green--------Red--------Blue
Black--------------------2.7Ω--------0.289Ω-----0.292Ω
Green------2.7Ω---------------------0.298Ω-----0.298Ω
Red----- 0.289Ω------0.298Ω-----------------------2.8Ω
Blue-----0.292Ω------0.298Ω---------2.8Ω-------------

The motor still behaved erratically.

I also measured the resistance of my working motor and found that the resistance of each pair was much higher (~34Ω) than my new motor. Is it possible that it could be defective? Or is it still possible that the 1.3A of this motor is causing the problem?

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Franklin97355
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by Franklin97355 »

The motor is probably not defective just not designed for the type of controller the shield is. There are other motor drivers that could drive this motor.

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shakezoola
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by shakezoola »

I can test the motor with another driver to make sure it is not defective.

To keep things simple consistent, I was hoping to use this motor shield with a motor that has more running torque than the nema 17 motor sold on the adafruit Web site.

Can you recommend a high torque stepper that works with this shield?

Thanks for your quick responses!

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adafruit_support_bill
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by adafruit_support_bill »

Based on the very low phase resistance, I believe that motor was designed for use with a current limiting driver.
https://learn.adafruit.com/all-about-st ... he-stepper

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shakezoola
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by shakezoola »

After reading the article in the link provided (not sure how I missed that one) it seems that this is not a 12V as indicated when I purchased it on-line.

Please correct me if I am wrong, but based on the current rating and resistance of the motor, it looks to be 3.5V. 1.3A x 2.7Ω = 3.51V
The motor I bought from Adafruit works fine because it is a 12V motor: .350A x 34Ω = 11.9V

Which would explain why this motor does not function correctly since the motor shield is designed for 5V-12V.

Am I on the right track?

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adafruit_support_bill
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by adafruit_support_bill »

... it seems that this is not a 12V as indicated when I purchased it on-line.
Yes, advertised specifications are often incomplete. Voltage specs in particular can be misleading.

I don't think that the vendors are being dishonest. I think some just don't understand what all the numbers mean. Motors designed for operation with current limiting drivers will often list a suggested supply current - with the assumption that the driver will be configured to limit the current to the max current rating.

When looking at motor specs for use with a non-current limiting driver such as the shield, the important numbers are the phase resistance and the current rating. You can figure out the voltage from there.
Am I on the right track?
Yes, it looks that way!

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shakezoola
 
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Re: Problems with Stepper motor connected to v2.3 shield

Post by shakezoola »

Awesome! Thanks to all for your help.

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