I’ve just thrown together a little demo for an XMega…

It’s a 4bpp (bits per pixel), 16 pixel high POV (persistence of vision) image generator.

It’s just 16 LEDs connected to an XMega32A4.

The program steps through each slice of a bitmap (held in flash memory). For each slice, it toggles the 16 LEDs rapidly on/off to produce the light intensity required for each pixel. For gamma correction, it maps the 4bpp source brightness to a 6bpp output. The output is encoded as binary-coded-modulation.The whole pattern repeats itself when it gets to the end of the bitmap.

Here’s a picture of the resulting effect:

And here’s the original bitmap I used (before adding a strange blob for testing purposes)