Arduino code for an Equatorial Barn Door Tracker.
Made using an 28BYJ-48 stepper motor and ULN2003 driver board, Arduino Mega ADK board, a breadboard, wire, pushbuttons, caps, resistors, some pieces of wood, a door hinge, 1/4"-20 threaded rod and nut, 1/4"-20 T-nuts, wire for guiding, screws, and lots of glue.
Credit for the main ideas and stepper motor help: https://partofthething.com/thoughts/making-a-cheap-and-simple-barn-door-star-tracker-with-software-tangent-correction-for-astrophotography/
https://github.com/partofthething/startracker/blob/master/controller/motor_control.ino
Credit for the button class: https://arduino.stackexchange.com/questions/48243/detecting-if-a-push-button-was-pressed-and-released