I need help with setting up the code and electronic parts for my project|movable projector-like screen

[dougp]

Hopefully this tutorial will help you get the concept of a state machine.  You'll need to decide on a good way to sense the top and bottom positions.

State machines

A common response to “I want my code to do A., then B., then C., etc.,” from the knowledgeable is “Use a state machine.” Many who are new to coding/programming have never heard of a state machine, although almost everyone is familiar with the concept. There are different ways to realize a state machine, like the very similar Sequential Function Chart, a construct used in Programmable Logic Controllers, but this discussion will deal only with the C++ switch/case construct - which is described bri…