My roommates and I used an Arduino Uno to run a stepper motor geared to a projector screen.
I laser cut and 3d printed the gears for the assembly. It is a 4:1 gear reduction for more torque when pulling the screen up.
The entire build is powered off of a 24v dc power supply. The stepper motor driver takes 24v and for the Arduino, we have a second buck convertor that steps down the voltage to 5v.
The only user input is a single switch. Because we are using a stepper motor that has no encoding or feedback, the state that the switch is in when the power is applied indicates whether the screen is starting from the unrolled or rolled position.
Really cool implementation using the stepper motor to control the projector. I am curious how you managed to get the gears on the roller. Also how much power did this need? is it all from the 5V output from the Arduino?