What could be the reason(s) that my stepper 28BYJ48 (with UNL2003) is turning only clockwice with the example code stepper_oneRevolution?
Does it make any noises/vibrations during the time it is supposed to be going the other way?
My best guess is that it's wired incorrectly.
Take a good look at this -> http://arduino-info.wikispaces.com/SmallSteppers
The wires 2 and 3 were wrong.
Now it is working as it should.