This is the Arduino AccelStepper library. It provides an object-oriented interface for 2, 3 or 4 pin stepper motors and motor drivers. The standard Arduino IDE includes the Stepper library (http://arduino.cc/en/Reference/Stepper) for stepper motors. It is perfectly adequate for simple, single motor applications. AccelStepper significantly improves on the standard Arduino Stepper library in several ways: Supports acceleration and deceleration Supports multiple simultaneous steppers, with independent concurrent stepping on each stepper API functions never delay() or block Supports 2, 3 and 4 wire steppers, plus 3 and 4 wire half steppers. Supports alternate stepping functions to enable support of AFMotor (https://github.com/adafruit/Adafruit-Motor-Shield-library) Supports stepper drivers such as the Sparkfun EasyDriver (based on 3967 driver chip) Very slow speeds are supported Extensive API Subclass support