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Just a quick question. Picking up some stepper motors, but confused at what voltage/current things are running off.

Ordering:
2 x Stepper Motor
2 x EasyDriver

An article says

You need some 12V source to the EasyDriver (the motor in this article is 12V) - This will be powering the stepper - Im using a 12V adapter - similar to the one in the illustration. Just make sure it is rated at least 750ma - A higher rating is better, and just means it wont burn out.

So does that mean if I got a plug which is regulated 12V 1A and powered the Arduino from that I could power a rail with VIN pin and that would safely supply the EasyDrivers? And I could then use the 5V pin to power everything else?

Just don't want to break anything! Thanks

  • This is the article. – Calco Sep 3 '15 at 16:24
  • To clear things up also: I was just trying to combine the project into one single power supply as it currently sends data wirelessly and this would mean I wouldn't need the USB to PC. Any suggestions as to what type of power supply I could use so I only have a single wall plug? – Calco Sep 3 '15 at 16:25
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As generic rule: avoid powering one device through another. It can cause strain on the middle-man device and it will be inefficient. The only few cases where this might make sense are when it's topologically inconvenient to connect everything to the centralized power supply. Or if the cascaded device requires a voltage that is not available from the power supply.

In your case you can power both the easy driver and the Arduino from the regulated 12v.

And you won't risk drawing too much current through the Arduino.

  • If I had a 12V 1A plug like this cut off the 2.1mm plug, exposed the wires and applied power to a breadboard rail. Would it be sensible to then power the arduino using the VIN pin and then use the same rail to power the easyDrivers? – Calco Sep 3 '15 at 18:04
  • I'd rather use something like this ebay.com/itm/… where you can power the breadboard with a voltage that will not heat up the regulator in the Arduino and you cna still access the raw 9V from a pin header. But yes, what you propose will work too. – Igor Stoppa Sep 3 '15 at 19:17
  • Where is the raw 9V pin on that board? I can only see the 5V and 3.3V jumper for each rail and the 5.5V/3.3V/GND pins? – Calco Sep 3 '15 at 20:15
  • Sorry, I mistook the component south of the switch for a pin header. No, you would have to solder a pair of wires from the pins of the connector, on the bottom side of the board. – Igor Stoppa Sep 3 '15 at 20:28
  • You should not run your stepper motor power through either the Arduino or (except for extremely small motors) a breadboard. – Chris Stratton Oct 3 '15 at 21:49
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Stepper Motor Control - one step at a time

This program drives a unipolar or bipolar stepper motor.
The motor is attached to digital pins 8 - 11 of the Arduino.

The motor will step one step at a time, very slowly. You can use this to test that you've got the four wires of your stepper wired to the correct pins. If wired correctly, all steps should be in the same direction.

Use this also to count the number of steps per revolution of your motor, if you don't know it. Then plug that number into the oneRevolution example to see if you got it right.

#include <Stepper.h>

const int stepsPerRevolution = 200;  // change this to fit the number of steps per revolution
// for your motor
// initialize the stepper library on pins 8 through 11:
Stepper myStepper(stepsPerRevolution, 8, 9, 10, 11);
int stepCount = 0;         // number of steps the motor has taken

void setup() {
    // initialize the serial port:
    Serial.begin(9600);
}

void loop() {
    // step one step:
    myStepper.step(1);
    Serial.print("steps:");
    Serial.println(stepCount);
    stepCount++;
    delay(500);
}
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The Vin pin is after the M7 protection diode, so you won't get quite 12 V out of Vin. Also, depending on the load, the diode might get warm.

I've also found that powering an Arduino from 12 V input (the maximum recommended) tends to get the voltage regulator hot.

Your other issue is that the motor power will be going through the Arduino board, to an extent (in the plug, through the diode, and out Vin) so any noise generated by the motor will be close to the processor.

I don't think your idea would break anything, it just might not be particularly reliable.

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