Any suggestions for Arduino shields capable of supporting NEMA 23 [Pololu #1478 (SY57STH76-2804A)]? I’ll need to support six of the stepper motors in total so it’d be helpful if I could connect two or three motors per shield (addressable and stackable). Thanks so much!
Hello.
We do not carry any Arduino shields for stepper motor drivers, and I do not have any specific recommendations for one. Most shields I’ve seen only support drivers with the standard STEP/DIR interface, so they would (at minimum) require some kind of pin remapping to make them stackable. Also, they usually only support drivers in the smaller 16-pin form factor, and I do not know of any drivers in that size that would be able to handle the 2.8A per phase of the #1478 stepper motor.
It could be difficult to reliably generate the STEP signals for 6 stepper motors at the same time, too. Instead, you might consider using a driver/controller that supports a higher level control interface, such as one of these:
-
Tic 36v4 USB Multi-Interface High-Power Stepper Motor Controller: The Tic 36v4 can easily handle the 2.8A per phase current rating of that motor, and it supports six different control interfaces, most notably for your application TTL serial and I2C, either of which would allow you to connect 6 Tics to the same bus and easily control 6 motors independently. You can find more information about this in the “Setting up serial control” and "Setting up I2C control section of the Tic user’s guide, respectively. The Tic also has various settings to do more advanced motion such as acceleration limiting without any additional overhead from your Arduino.
-
High-Power Stepper Motor Driver 36v4: This board has similar power characteristics as the Tic 36v4, but does not have many of the extra features such as USB and non-volatile settings. It needs to be configured via SPI on each startup, then you can continue controlling it via SPI or the STEP/DIR interface.
Brandon
Hello!
I see, I was looking at those Tic stepper motor controllers and I just found out I can control them via USB using a PC, that way I won’t need to use a microcontroller.
The Tic 36v4 has a operating voltage of 8V to 50V while the stepper motors I mentioned have a rated voltage of 3.2V. Can I get past this? And if I used the USB connection directly to PC, since that has a standard rating of 5V at 0.5A, I’ll have to connect an external power supply right? Thanks so much for your help!
You can safely drive a stepper motor using a higher voltage than it is rated for as long as you are using a current limiting driver like the ones we carry (including the Tic controllers). Doing so can be beneficial too, as it allows you to reach higher step rates. You can find more details in the first question under the “FAQs” tab of the motor’s product page. As you described, you should use an external power supply for the motor.
Brandon
Hello!
Right, thanks so much, that makes a lot more sense! So if I get any power supply with at least 2.8A and a voltage between 8V and 50V, the voltage regulator on board would make it work out?
Figuring out the current requirements of the power supply is a little more complicated than that, and the driver uses current chopping, which is different than a voltage regulator.
The #1478 stepper motor is rated for 2.8A per phase, and it has 2 phases (or coils). This means if you energize the coils at the rated voltage of 3.2V, each one would draw 2.8A. The actual current the driver sends through each coil will depend on the particular step index the motor is at, but it should never be greater than the rated current, so this is a safe value to use. Since power is conserved (i.e. power in equals power out), if you use a higher voltage on the input of the driver, the input current can be lower to achieve the same output power. For example, if you power it with 12.8V, the input current required would only be 0.7A per phase (i.e. 1.4A total).
As I mentioned above, this is a bit of an over-simplification (i.e. most drivers only power each coil to 71% power on full step indexes and there are efficiency losses that I’m not considering), but it should work fine for determining the minimum requirements of a power supply for most cases.
Brandon
Hello again!
Right, seems complicated. To simplify things a lil bit more, if I used this Pololu wall power adapter (#1774), would it work? If not, could you suggest me a power adapter in your shop that would work? Thanks so much for your time!
Hello.
Yes, that 12V, 3A wall adapter would be fine for powering a single #1774 stepper motor.
If you wanted to power all 6 of your steppers from a single 12V source, you would want one that can handle at least 9A (ideally a little more than that, especially if you are powering other devices in your system with it). Alternatively, if you used a 24V supply, I would recommend one that can handle at least 5A. I do not have any recommendations for supplies like that, but they should be fairly easy to find on larger marketplaces like Amazon.
Brandon
Hello!
I see! Thanks so much for all of your help! I think I’ll just power each one individually, that way I don’t have to do a ton of wiring!