External power and GND

Hi,

First post on the forum, hi everyone!

I'm very new to electronics in general - apologies if my question is very basic :slight_smile:

I'm using an Arduino Uno and a tb6560 stepper driver to control a nema23 stepper motor with 1.0A per coil.

Right now, I have the Arduino powered by USB and the stepper driver powered by an external 12v 5A PSU. I'd like to consolidate the project and use the external power supply to power both Arduino and the stepper driver. To do this, I plan to split the +12vdc and V- leads coming out of the PSU, and run them to both Arduino (via barrel jack) and the driver box.

My question is:
When powering the Arduino via the barrel jack, does the V- from the barrel jack serve as the reference ground for the arduino? Or do I need to run a separate wire to one of the GND pins on the board?

Thanks in advance,. Lee

Leeko:
When powering the Arduino via the barrel jack, does the V- from the barrel jack serve as the reference ground for the arduino?

Yes.

But be careful how much current any other circuits draw at 5V. You could cause the Arduino's regulator to overheat and fail.

Thanks very much

I had also read that caution is needed when powering both arduino and an external device from the same power supply, but my understanding is that a 1a per coil stepper should be within safe limits. Thanks for mentioning it though!

but my understanding is that a 1a per coil stepper should be within safe limits.

Your understanding is wrong, it is not.
The 5V regulator is only rated at 1A total, and not at a 12V input because the power dissipated is way too much for the heatsink.

See:- Power Examples

Ok, thanks for the correction. What would be the best way of doing this? The project needs to run away from a computer, so USB powering the Arduino isnt an option. Running 2 separate power supplies (one for the Arduino and one for the driver) seems like an inelegant solution. Is there a better way?

Thanks,

Lee

If the stepper driver module is what handles the power for the steppers, power from the Uno regulator is minimal and you don't have any problems. The Uno only provides control signals. You just have to be cautious if you are trying to power anything else with the Uno voltage regulator. Having to drop that much voltage reduces the safe amount of current that can be sourced.

Hi,

The stepper driver is an a4988, attached to one of these:

cnc shield

The cnc shield sits on top of my uno. It has separate 12vdc inputs, and with no power applied to these it does not drive the motor. For power, I split the + and - outputs from a 12vdc 5a wall wart, and plugged them into 1) the arduino barrel jack and 2) the power inputs on the cnc shield.

Iā€™m not sure how to tell whether the stepper driver/cnc shield is handling the power, though it seems like that should be the case?

Thanks again for your help

Lee

Yes, the shield has motor drivers modules that plug into the top, which are what handle the power. The Uno handles control signals.

Thanks Tinman! Good to know Iā€™m not that far off the mark :slight_smile:

Lee