July 30, 2012 AT 2:00 am

The Laser Doodler

Over at ch00ftech, there is a great tutorial on using an Adafruit LED matrix as a display, and a sensor.

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. But how do you make an LED matrix into a sensor matrix?

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