So when this display arrived in the mail, I wanted something to do with it so I could get accustomed to the pinout and LED intensity. I thought it would be fun to create a simple display that can be “drawn on” with a light source. An LED would work, but using a laser allows you to doodle from across the room if your hand is steady enough.
In order to accomplish this, the display needed to alternate between being a display and being a sensor. During its sensor stage, it records where the laser dot is located, and during its display stage, it lights up the LED associated with the laser dot’s position.
[via Embedded Projects]