Rather than write a bunch of stepper motor code himself, he installed and ran a four-axis fork of grbl on the Arduino, turning it into a stepper motor controller.

Leveraging the Trinamic TMC2208 stepper motor driver gives Ethersweep silky smooth and quiet motor control, which could be very important for some applications.

Makers, developers and Arduino enthusiasts searching for silent stepper drivers with high resolution encoders which are also Arduino compatible.