I have built a stepper motor controller using an Arduino Uno, 28BYJ-48 12VDC Stepper Motor and a ULN2083A (Darlington Octal Buffer) to drive it with. I believe I have it working ok and happy to share where I am up to at the moment with others who may find it interesting and a good place to start, and then improve on.
The motor is pretty light weight, but thanks to in-built gearing, quite useful. It has been the topic of many other people's articles, so no originality claimed in the concept. It has been sold as 'used for oscillating vanes on air conditioners' among other things, so an ideal hacking target. The program has ended being a handy tool to investigate bipolar steppers (especially those with a single common to 4 coils), but can be streamlined considerably once the pattern of coil excitation is discovered.
ASCII artwork for circuit schematic and nostalgia!