Can the motor shield power the Uno

Hi, I'm complete novice at this but I've been researching so I can create my own barn door star tracker (save on buying one for £300 :slight_smile: !)

I plan on using an Arduino Uno in conjunction with an motor shield to drive a stepper motor.

As this needs to be a mobile item it will have to run off a battery (I have been donated a 16v 5000mah lipo).

From my research I think I can run the battery in through the external power section of the motor shield, and with some configuration, this will be also power the Uno - meaning I don't need two power supplies.
Is this right?

I appreciate your help

Some motor shields can provide 5V for an Arduino, but a motor shield is not a good starting place for the project.

Decide on the mechanism and the motor required to drive it first, then pick the appropriate motor driver and go from there.

You can always use a separate, tiny and cheap 5V step down converter for the Arduino. Pololu has a great selection, and the best selection of motor drivers, too.

Thanks for your reply!

Why do you say the motor shield is not the best starting place? It seemed like a good option to me, but as I say I'm novice at this.

Barn door trackers bring up lots of results.

The main consideration would be the total weight to be moved.
That would help dictate the motor required which in turn would decide the motor driver.

AVOID the ULN2003 and L293D drivers as they can be power hungry.
Indeed Polou has a great selection but if price is a consideration there are multiple other choices.

Would suggest look at existing projects for one that is closest to your needs and go from there.
Google will help you on many aspects.

As for powering the Arduino from the same battery a small step down module of some description would be my prefered choice to bring the voltage down between 7-10 volts then you could use the barrel jack.

EDIT
SOmething like either of these two would provide you with a great starting point.
This would allow you to use MICROSTEPPING which could be exceptionally useful for a smooth track.

This is also very easy to use as well.

Why do you say the motor shield is not the best starting place?

Because the motor shield might not be appropriate for the type of motor that the project requires.

If the mechanism doesn’t work, no electronics will fix the problem.

Thanks for the replies!

I should really give a little more info.

I was planning to use a NEMA 17 stepper rated at 2A and a drv8825 to run it. But as I say because I'm a novice (I'm a sort of photographer not an electronics expert

The DRV8825 cannot deliver 2A continuously without special cooling (at best 1.5A), so using that driver, a 2A motor cannot deliver the full rated torque.

As a barn door drive requires a gearbox and/or threaded rod mechanism, it is unlikely that you will need a motor that powerful.