I've just received a Motor Shield v3.0 which I immediately connected to a stepmotor as I need to control such a beast.
I've created a small sketch based on the example included with the Arduino distribution, and it works - almost: I can make the motor move in one direction or the other - but not both.
The board has a position for a couple of jumpers between the two logic ICs, but not much documentation about how to connect them: Without jumpers, the motor won't move though it vibrates as it works. With a jumper shorting E1/E12, the motor will move in one direction - but not the other; shorting E2/E22 instead, the motor will move in the opposite direction - and only that.
Now you might think that using two jumpers would allow the motor to run in both directions - but that's not the case: With two jumpers, the motor behaves like it does without any jumpers.
What would be the correct setup if I want the motor to be able to move in both directions?
Considering there are many different motor shields a link would be helpful. Who makes the shield?
Not sure where your problem is. A motor is only able to run in one direction at a time. An important thing to note about stepper motors is you need to know how many steps it has per revolution. This may be a helpful link for you. It may not be the motor shield you have but it may still help. http://www.ladyada.net/make/mshield/use.html
I do know that a motor will only run one direction at a time. However, according to the documentation in Stepper.h, calling step(50) should move the motor 50 steps in one direction, calling step(-10) should move it 10 steps in the opposite direction. I can make one direction work - but not both.
I figure this could use a bump since it's a dead topic at the top of a Google search for "arduino motor shield documentation". There's no documentation available for the (seemingly-) official Arduino motor shield linked in the above post, and it's putting a serious damper on my efforts at driving a stepper motor at all... scarce, unclear documentation at best. The pin header on the board merely says "motors", with no description to what pin does what, or how to connect the motor. Stab in the dark I just went straight-down 1, 2, 3, 4 to winding 1 (a), winding 1 (b), winding 2 (a), and winding 2 (b) (with no particular organization of A/B, since I had to pin it out via a multimeter).
tl;dr: someone please pick up this topic and answer this guy's question, because Google wants to know too
edit: also worth noting, my board is the same one as linked, but I've only got "E2" and "E1" on my board (next to the 14-pin IC), no E11/E22... but I think they have something to do with the unused "encoder" functionality of the board...
However, according to the documentation in Stepper.h, calling step(50) should move the motor 50 steps in one direction, calling step(-10) should move it 10 steps in the opposite direction. I can make one direction work - but not both.