Armindo:
- But I cant get enough speed. The AccelStepper seems to give more speed and I cant understand why (the library is more optimized?).
Do you mean you can't "turn up" the speed any higher, or do you mean the stepper fails to rotate (and just buzzes) at a higher speed?
By the way, you don't need a library to drive a stepper. Just look at the Arduino stepper library. In the main .cpp file is a big commented section that shows the switching sequence for the motor coils. Just read that, understand it, then simply use a bunch of digital writes and delays to get any speed you want (including speeds WAY faster than any stepper can handle).
Also, because of the inductance of the motor windings, the drive current starts out at (virtually) zero and rises up to a max dictated by the winding resistance. To get better response, use a higher supply voltage for the motor and drive it through an appropriate resistor. The higher voltage will "charge up" the inductance faster, and the resistor will limit the winding current. The motor will perform a LOT better that way.