Motor shield v2

[njames878]

Hi,

I wonder if anyone could give me some troubleshooting suggestions, as I'm having problems getting my motor shield to work. I'm trying to run two stepper motors.

The steppers are very standard 4 wire bi-polars with one blue/green wire pair and one red/black wire pair

I've soldered on all the headers, installed an example sketch and library, connected a 12v lead acid battery to the shield power terminals and a USB power connection to the arduino. When I try and run the sketch, I get the following:

- The green led lights up on the shield
- The motors twitch and judder, but do not move consistently
- The motor controller chip next to motor ports 1 and 2 gets very hot. The other motor controller chip remains cool.
- I have not installed the power supply jumper, so the two boards are powered separately.

Things I've tried/checked.

- The header soldering looks OK. Difficult to tell, but I can't see any obvious flaws
- The header is properly attached to the Arduino. No misalignment or pins not seated.
- I've got the serial monitor open, and the sketch appears to be looping through correctly.
- Before I moved to a lead acid battery, I used a switched mode power supply at 13V. Could this have fried the shield?

Any help gratefully received.

Thanks,
Nick

[adafruit_support_bill]

The steppers are very standard 4 wire bi-polars with one blue/green wire pair and one red/black wire pair

Not sure what a 'standard' motor would be. Stepper motors can have widely varying electrical characteristics. Do you have an electrical spec for these motors? At the very least, we need to know the phase resistance. If you can't find a manufacturer's spec, please measure the resistance across each wire pair.

[njames878]

Hi Bill,

Thanks for coming back so quickly. The motor is a 17HS19-200451 ( https://www.omc-stepperonline.com/hybri ... 004s1.html). Clicking through on the link, I think that I may have discovered the problem. The rated voltage on these motors is 2.8 volts, and I have been driving from a 12 volt source. I take it I have fried the board, and possibly damaged the motor? Can I use this shield with these motors, or is there another NEMA 17 motor or Adafruit board that you would recommend?

Thanks,

Nick

[adafruit_support_bill]

Manufacturer's specs do not always mean what a sane person might think they mean. If you tried to run that motor at 2.8v, the performance would be BANNED. I would expect that most of these motors get run with a 24 or 36v supply - BUT - they are driven with a current limiting driver. Unfortunately, the motor shield does not have current limiting and is not compatible with this motor.

The critical number is this one: "Phase Resistance: 1.4ohms". The low phase resistance tells me that the motor was designed with a current limiting 'chopper' driver in mind. The 2.8v is simply an application of Ohm's Law to the phase resistance and the rated current. For an explanation of how limiting the current can improve the performance, see this guide: https://learn.adafruit.com/all-about-st ... he-stepper

This motor is a good match for the shield
https://www.adafruit.com/product/324

We also have some current limiting drivers that would work with the motor you have:
https://learn.adafruit.com/current-limi ... 1?view=all

[njames878]

Hi,

Thanks for the very comprehensive reply. I’ve actually got a new motor shield and a 12v stepper, and it’s all working fine now!

Thanks again
Nick

[adafruit_support_bill]

Good to hear you have things working. Thanks for the follow-up.