Unipolar stepper motors sequencer library for Arduino, by Tennessee Carmel-Veilleux.
See the smarsbar robot repos for a sample of use.
Install in your Arduino libraries folder. Code is portable and has been tested against Adafruit Feather M0 (ARM Cortex-M0-based, similar to Arduino Zero), Arduino Uno (AVR) and Adafruit Trinket (AVR).
Full tutorial will come later if I have time :)