The project uses an ATtiny24 to control a 28BYJ-48 stepper motor's position (see control sequence for the motor in half- and full-step mode). Three potentiometers control the OPEN and CLOSE position angles and the speed of movement (see positioning picture). Very flexible and tiny, battery operation possible (see schematic picture). Assembler source code and 40-by-50 mm PCB layout (in gif-format) provided.