Thanks a lot guys!!
Just a doubt: I see that the stepper supply Voltage is not really important (but the Current is instead), but the TB6600 is rated for 9-42VDC, and my stepper is at 3.1V
I guess I’m going to burn the stepper, right?
Not at all, steppers don’t have a voltage rating (other than insulation breakdown), only a current rating.
The stepper driver controls the motor current, all is well.
The key electrical characteristics of a stepper are current, resistance and inductance, and its the inductance
that dominates. Lower inductance mean higher speeds are possible from a given supply voltage. The driver
must be set to match the nominal current (or somewhat lower if you don’t need full torque rating). The driver
relies on the winding inductance to function, note, never attach a stepper driver to a dummy resistive load, you
will probably fry it, and never disconnect the motor windings from a powered-up driver either.