Motor Shield v2.3 - Stepper Motor RPM randomly wrong at low

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CarboxylicAcid
 
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Motor Shield v2.3 - Stepper Motor RPM randomly wrong at low

Post by CarboxylicAcid »

I'm finding that the RPM on the stepper motor is randomly wrong at low RPM settings and it won't go slow enough for what I need.

I have the latest library on my Arduino project and this problem was spotted in 2017 and someone posted a fix but it's still there...

viewtopic.php?f=31&t=115397

I've tried the fix and unfortunately it doesn't work and won't compile.

Does anyone know a work around to fix this?

Also why hasn't this been fixed in the official library when they have been aware of the problem for almost 5 years?

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adafruit_support_bill
 
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Re: Motor Shield v2.3 - Stepper Motor RPM randomly wrong at

Post by adafruit_support_bill »

Please post the electrical specs for the motor you are using.
Also please post the power supply you are using.

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CarboxylicAcid
 
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Re: Motor Shield v2.3 - Stepper Motor RPM randomly wrong at

Post by CarboxylicAcid »

adafruit_support_bill wrote:Please post the electrical specs for the motor you are using.
Also please post the power supply you are using.
I am using a Usongshire Nema 17 (US-17HS4401S) stepper motor with a 5V 5Amp power supply.

If I set the RPM as 5 for example then it will rotate faster than when set at 15 which seems to be the same issues in the thread I posted and when looking at the library code it doesn't seem to have changed from what was posted there (but I don't know enough about it to say for sure).

I have found that when I use the "onestep" instead and do it every 5ms, 10ms etc then I can get the speed I want but ideally i would like to use the "step" and set the RPM as it is much easier to code.

Thanks for looking into this.

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adafruit_support_bill
 
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Re: Motor Shield v2.3 - Stepper Motor RPM randomly wrong at

Post by adafruit_support_bill »

That motor is not compatible with the motor shield. It has a phase resistance of just 1.5 ohms, so with a 5v supply it have a peak current draw of 3.33A per phase. The shield is only rated to deliver 1.2A. The drivers do have thermal overload protection. But chronic overloads will eventually kill the shield. Motors like that are intended for use with current limiting drivers such as the DRV8833: https://www.adafruit.com/product/3297

I will check with the maintainers of the library regarding the timing issues.

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CarboxylicAcid
 
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Re: Motor Shield v2.3 - Stepper Motor RPM randomly wrong at

Post by CarboxylicAcid »

adafruit_support_bill wrote:That motor is not compatible with the motor shield. It has a phase resistance of just 1.5 ohms, so with a 5v supply it have a peak current draw of 3.33A per phase. The shield is only rated to deliver 1.2A. The drivers do have thermal overload protection. But chronic overloads will eventually kill the shield. Motors like that are intended for use with current limiting drivers such as the DRV8833: https://www.adafruit.com/product/3297

I will check with the maintainers of the library regarding the timing issues.
I didn't realise that. Are there any Nema 17 size stepper motors which are compatible with the board?

Also thanks for investigating the timing issue.

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