Motor shield v2.3 AC/DC wall adapter as power supply

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therm0map
 
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Motor shield v2.3 AC/DC wall adapter as power supply

Post by therm0map »

I'm working on a project involving 1 stepper motor (Bipolar / 20 ohm/phase / 500mA/phase / 10V) and 2 SG90 mini-servos (5V operating voltage). I'm planning on attaching everything to an Arduino Uno R3 via the Motorshield v2.3. I'm planning on using a 12V/2A AC to DC wall outlet converter to power the stepper motor and mini-servos via the power terminal block.

Is it a bad idea to power the power terminal blocks via a DC wall adapter like this one (link)?

I also know that the individual motor driver chips can handle 1.2A, and with the 12V power supply the stepper motor should be drawing about 1.2A. However, I couldn't find anything on the max current rating for the power supply, and I don't want to burn out the motor shield or any of my components. So is the 2A on the power supply OK, or should I find a power supply / battery that provides more like 12VDC/1.2A?

Thanks!

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Franklin97355
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by Franklin97355 »

That PS says 12 volt 2 amp so it should be able to supply 2 amps but your motor spec says 10 volts so I'd be a little worried about the over voltage.

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adafruit_support_bill
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by adafruit_support_bill »

Your motor windings are rated for 500mA/phase. With a 12v source and a 20ohm phase resistance, you will be driving them with 600mA. This will likely result in your motor overheating.
So is the 2A on the power supply OK, or should I find a power supply / battery that provides more like 12VDC/1.2A?
Neither. The shield does not have current limiting. You should not drive this motor with more than 10v - unless you are using a current limiting driver set for 500mA/phase.

https://www.adafruit.com/product/3297

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therm0map
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by therm0map »

Thanks for the quick replies! So the only voltage/current that would work for the power supply (without a current limiter) is 10V / 1.2A? Or is 2A fine since the stepper motor would only be drawing 1.2A in that case?

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adafruit_support_bill
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by adafruit_support_bill »

So the only voltage/current that would work for the power supply (without a current limiter) is 10V / 1.2A? Or is 2A fine since the stepper motor would only be drawing 1.2A in that case?
Using the shield, you must use a power supply of 10v or less to keep within the current rating of the motors.
At 10v with a 20ohm phase resistance, your motor will draw 500mA per phase or 1.0A total.
https://learn.adafruit.com/all-about-st ... he-stepper

So, using a 10v supply you will need one rated for 1A or more.
A 9v/1A supply like this would also work. The motor would have about 10% less torque than with the 10v supply: https://www.adafruit.com/product/63

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therm0map
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by therm0map »

Awesome, thanks for the great support/advice

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ptiger
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by ptiger »

I have a question about using many of these together. I see there are what look like 10k ohm pullup resistors on the SDA and SCL pins on the shield. Would the parallel equivalent resistance with many pullup resistors on the same bus create too strong of a pull-up for the bus to operate correctly? I will have 8 shields (essentially), a Teensy LC, and of these I2C expanders https://www.adafruit.com/product/732 on the bus as well. Thanks!

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adafruit_support_bill
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by adafruit_support_bill »

ould the parallel equivalent resistance with many pullup resistors on the same bus create too strong of a pull-up for the bus to operate correctly? I will have 8 shields (essentially),
Yes. Too many pullups will create problems. Typically 3 or 4 sets of 10K pullups on the bus is no problem. If you have more than that, you can remove some of the pullups (or cut the traces to them). Or you can isolate subsets of the bus using a multiplexer.

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ptiger
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by ptiger »

Thanks! Would one pair of 10k ohm resistors be sufficient?

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adafruit_support_bill
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by adafruit_support_bill »

For most applications, 10K works fine.

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fede90
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by fede90 »

Hi,
I'm working a project to drive a stepper motor with Arduino Mega .I would like to know if it is possible to use stepper motor 42BYGH48 with Adafruit Motor Shield V2.3.
Thanks
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datasheet_stepper (1).png
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adafruit_support_bill
 
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Re: Motor shield v2.3 AC/DC wall adapter as power supply

Post by adafruit_support_bill »

No. That motor is designed for use with a current limiting driver such as the DRV8833. https://www.adafruit.com/product/3297

https://learn.adafruit.com/all-about-st ... he-stepper

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