adafruit-motor-shield-v2-for-arduino has no current limiter?

[dan77062]

I bought the adafruit-motor-shield-v2-for-arduino:
https://learn.adafruit.com/adafruit-mot ... o/overview

to drive a stepper motor but am surprised to find that there seems to be no way to current limit the output to the coils. Most stepper motor drivers allow current limiting so that you can run at a voltage that would produce currents well beyond the coil limit. That is good to do, as the waveform is sharper, producing cleaner steps.

For the stepper motor I am using (Smart Automation SM35HT36-1004A, the NEMA 14 stepper that comes with the Inventables camera slider kit) the coil resistance is only 2.7 ohms and the current limit is a bit over an amp. One would normally drive this motor with a 12V source and current limit it to one amp.

Is there no way to do that with this motor driver board?

I saw this post with a similar question, sounds like indeed this board does not current limit, but just want to be sure:
viewtopic.php?f=31&t=51469&p=260004&hil ... it#p260004

Assuming that the board cannot current limit, I figure this is the best alternative:
http://www.pololu.com/product/2133

[adafruit_support_mike]

You're right that the Motor Shield doesn't have the capacity to limit current. It's a simple, light-duty controller.

If you want a chopper controller for higher-power motors, Pololu is a good source.

[dan77062]

Thanks for the quick reply. The only problem with the Pololu board is that it does not come in an arduino shield format. So there is the hassle of making an enclosure for it and running the wires over, etc. Do you know of a stepper motor driver that does current limiting and is an arduino shield?

[Franklin97355]

http://www.motioncontrolshop.com/produc ... or-arduino

[adafruit_support_bill]

The Synthetos G-shield does current limiting: https://www.adafruit.com/products/1750

[dan77062]

Good suggestions, thanks.

I just found this one too, only $13.
http://www.robotshop.com/en/dual-steppe ... duino.html

[JuliaS]

Was running steppers through the shield off a 12V line of an ATX power supply and the H-brides were spiking into 70 degree territory within seconds on full steps. The need to limit current was obvious. Heatsinks would've been hard to place with such shield design, and would prevent me from stacking subsequent shields.

This is the simplest solution I was able to produce putting about $10 worth of parts on a perf board:

http://us1.webpublications.com.au/stati ... 54_6mg.jpg

LM317 is used as the load regulator and MJE2955 PNP's serve as dissipators. Fan portion (left half of the circuit) is optional, depending on the size of transistor heatsink and how much energy you'll be venting. I managed fine without it.