I have an Uno and an Adafruit motor shield.
At the moment my project is using a 1.6a 12v stepper motor and my power is connected directly onto the power input on the shield. The Uno is powered from a USB connection.
When I go live with the project I will be ditching the USB in favour of a power supply. My ideal situation would be to use one power supply to power the UNO and use the power bridge jumper on the Adafruit to route power from the UNO to power the Adafruit and the motor.
Can and should I do this and what rating power supply can I use?
Hello,
An Uno cannot and should not power a motor above a small servo (maybe not even that?) If you powered the driver board off of the Uno VIN pin, you could take as much as 1 amp before it would be damaged. The Digital I/O pins can output max 40mA. Your motor driver/stepper motor is 1.6 amps AND 12v which is also quite high for the arduino. That being said, you will fry your board if you try to power the motor via the arduino.
If you could link info about your motor shield, that would help a lot with how to design it...
On some motor shields, like this one here there is a 5v output that you can connect your arduino to.
Check out this picture I made that shows how I would connect all the power...
For power rating, you can power the motor driver and arduino off of a 12v power supply and since your motor is 1.6 amps, I would go for at least a 2 amp 12v power supply minimum.
Hi, amarotica, that sounds very simple and sensible. Thank you for the input.
I got my initial information from this article produced by Adafruit:
If you would like to have a single DC power supply for the Arduino and motors Say a wall adapter or a single battery pack with 6-12VDC output, simply plug it into the DC jack on the Arduino or the 2-pin power terminal block on the shield. Place the power jumper on the motor shield. Note that you may have problems with Arduino resets if the battery supply is not able to provide constant power, so it is not a suggested way of powering your motor project. You cannot use a 9V battery for this, it must be 4 to 8 AA batteries or a single/double lead acid battery pack. If you would like to have the Arduino powered off of USB and the motors powered off of a DC power supply Plug in the USB cable. Then connect the motor supply to the power terminal block on the shield. Do not place the jumper on the shield. This is a suggested method of powering your motor project as it has a split supply, one power supply for logic, and one supply for motors If you would like to have 2 separate DC power supplies for the Arduino and motors. Plug in the supply for the Arduino into the DC jack, and connect the motor supply to the power terminal block. Make sure the jumper is removed from the motor shield. "
As you can see they intimate that you can use the jack on the Arduino for all your power needs! I was sceptical about the power, hence the question.
I am unable to find any documentation telling me whether the Adafruit Motor Shield has a 5v output to enable the configuration suggested by amarotica.
If anyone can help before I have to go and purchase a different motor shield.
It also looks like my 1.6amp motor is above the 1.2amp/motor limit anyway. So either I got for a driver board that has a higher current or I switch to a lower current motor (which might still be an option).
If I go for a 0.67amp motor I am sure this changes how I can power it? I am assuming that below 1.2 amp I use the adafruit instruction for driving a motor from the Arduino?
It would be wise to use a motor driver than can comfortably supply the full current for your motor.
I don't think the Adafruit motor shield in your link is designed to power an Arduino. If you conclude that it is otherwise suitable it would be straightforward to make up a voltage regulator using a 7805 regulator. You can probably also buy ready-made 12v to 5v regulators.
I have bought both a motor and a shield, but I take the approach that this is my first time out into such a project and there is a learning curve. Neither will go to waste as I have other ideas I can use them for. My aim is to get the best solution that is both clean and fit for purpose and I accept that in any learning curve there are mistakes, changes and uninformed decisions resulting in costs.
RigidCollision:
I accept that in any learning curve there are mistakes, changes and uninformed decisions resulting in costs.
That is a reassuring attitude and not as common as it should be.
I would certainly try to get the project working with the motor and shield you already have before deciding to buy anything else - apart from the extra voltage regulator.
