Arduino UNO R3 + Arduino Motor Shield R3 + "Mercury Motor" Stepper

Hello I have the setup as in the picture below:

The motor is a "Mercury Motor", this is the specification sheet: Power comes in from a 12V battery.

When I try to run it, the motor goes back and forward, but does not move continuously in one direction. I am initialising pins 3,11,12,13 as in:

Stepper myStepper(motorSteps, 3,11,12,13)

Can anyone please help me out? What am I doing wrong?

Thanks, Peter

Did you try swapping one pair of wires from the motor?

Cheers, Kari

I have this very simple code:

#include <Stepper.h>

Stepper myStepper(200, 3,11,12,13);

void setup() {

void loop() {
  // Step forward 10 steps:

When it executes, the motor takes 4 steps (clockwise and anti-clockwise) in this order: cw, ccw, ccw, cw. So basicly it comes back where it started.


Did you look at the Reply #1? You didn't answer to the question.

Cheers, Kari

Yes, I have tried that, with some ‘interesting’ results:

  • swapping yellow / blue: ccw, cw, cw, cw
  • swapping green / red: ccw, ccw, cw, ccw
  • swapping yellow / blue + green / red: cw, cw, ccw, cw

Seems like someone else is having problems too;

I hope you got your answer from somebody who has played with that shield!

Cheers, Kari


I swapped pins to:

Stepper myStepper(stepsPerRevolution, 3,13,11,12);

I also changed the speed:


Now it moves but the positioning isn't accurate.

I'll look through the stepper library to see if I can make this motor run better.