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Different voltage motors on same featherwing driver
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Different voltage motors on same featherwing driver

by ephall on Wed Jun 29, 2022 8:09 pm

Hi! I have a quick clarifying question in regards to the featherwing dc + stepper motor driver (product #2927), and running it with motors of varying voltages. I've seen on the documentation that you can run both DC and stepper motors on the same driver, however I can't seem to find whether the voltages of the two motors have to match (ie. the stepper is at 12V, therefore the DC motor must match).

It looks like this is implied in the tutorial as their is a picture of what I think is the normal hobby motor which runs at 6V, and a stepper motor which should run at around 12V. However, I just wanted to clarify before I purchase/do something dumb.

My goal is to run a NEMA 17 at 12V, and two of the 1:298 encoded DC motors at 6V at the same time via bench top power supply. Thanks for the help!

ephall
 
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Re: Different voltage motors on same featherwing driver

by adafruit_support_bill on Wed Jun 29, 2022 8:33 pm

My goal is to run a NEMA 17 at 12V,

NEMA17 is not an electrical specification. Please provide a link to the specifications for the actual motor you plan to use.
My goal is to run a NEMA 17 at 12V, and two of the 1:298 encoded DC motors at 6V

Assuming that you are referring to these motors: https://www.adafruit.com/product/4641
They are rated for "4.5 to 6V DC (nominal)". Which means they can can handle those average voltages on a continuous basis. If you run them at a higher supply voltage, you should limit the maximum throttle via the featherwing library. That will limit the average voltage to the motor.

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Re: Different voltage motors on same featherwing driver

by ephall on Wed Jun 29, 2022 9:59 pm

My bad, this is the stepper I was thinking of on the adafruit site: https://www.adafruit.com/product/324.

So I read some of the docs and it seems like the throttle in the featherwing library goes from -1.0-1.0, is that proportional to the input voltage or is it more of something I just need to figure out via measurement?

I guess I'm just getting tripped up by the docs on the driver, as I kinda feel like it implies that after you apply 5-12V from the supply, you can then proceed to drive any motor with any voltage on the driver as long as it's between a range:

-"the TB6612 chipset provides 1.2A per bridge with thermal shutdown protection, internal kickback protection diodes. Can run motors on 4.5VDC to 13.5VDC"

-in reference to the power pins: "You must provide an external power supply for driving the motors. Provide 5-12V DC power + ground on these pins".

I've also seen several pictures of this driver and the larger Arduino one showing multiple motors of all different types connected to it, without mention of the throttle. Example here: https://learn.adafruit.com/adafruit-ste ... uino-usage and here: https://learn.adafruit.com/adafruit-mot ... o/overview. Are these pictures just for show or is this configuration possible? I also checked the "Motorparty.ino" example sketch on GitHub, and I can't seem to find it there either, but both a stepper and DC motor are initialized in the code.

Thanks a ton and sorry for the confusion, much appreciated for your help!

-Eric

ephall
 
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Re: Different voltage motors on same featherwing driver

by adafruit_support_bill on Thu Jun 30, 2022 6:39 am

So I read some of the docs and it seems like the throttle in the featherwing library goes from -1.0-1.0, is that proportional to the input voltage

That is proportional to the supply voltage. The driver uses PWM to control the average voltage gong to the motor. https://docs.arduino.cc/learn/microcont ... log-output
The throttle setting controls the PWM duty cycle and the direction of the current flow.

I kinda feel like it implies that after you apply 5-12V from the supply, you can then proceed to drive any motor with any voltage on the driver as long as it's between a range:

You need to consider the characteristics of the motors - and what kind of performance you expect from them.

Are these pictures just for show or is this configuration possible?

That configuration is possible.
If powered with 5v, the stepper would still work. But it would have about 40% of the torque it would have at 12v.
If powered with 12v, you would need to be careful with those little DC motors and not run them at full throttle for extended periods.

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