The expansion board can be used as engraving machines, 3D printers driven expansion board, a total of 4 slots channel stepper motor driver module ( note that this board does not include A4988 stepper motor driver module, you can purchase another in the shop ) can drive 4 -way not stepping motor, stepper motor and each way takes only 2 Ge IO ports, ie . 6 Ge IO ports can be well managed 3 stepper motors, very convenient to use, farewell conventional stepping motor cumbersome operation. Two UNO module IO port correspondence between presentation.