The expansion board can be used as engraving machines 3D printers and other driven expansion board a total of four slots stepper motor driver module can drive four stepper motor stepper motor and each road only need two IO port that is six IO port can be be well managed three stepper motor very convenient to use say goodbye to traditional stepper motor operation cumbersome. It is noteworthy: stepper motor reverse circle stop one second and then turn around the positive so the cycle. In connector A4988 module when careful not interpolated reversed. Stepper motor wiring is: 2A 2B is a set of (red green) 1A 1B to a set of (blue yellow) wants to change direction change in the position of one group can be for example exchanged with 2A 2B.