Matthias "bitluni" Balwierz Creates a Tiny POV Display Controller Core in Tiny Tapeout

German maker Matthias "bitluni" Balwierz has shown off another of his custom application-specific integrated circuit (ASIC) designs from the latest Tiny Tapeout production run: a dedicated controller for a persistence-of-vision (POV) display.

"I made a lightsaber five years ago that used [a] gyroscope and NeoPixels to display images in mid-air," Balwierz explains of the inspiration behind his project, one of three submitted to Tiny Tapeout 2. "I thought this also would be possible with the kilohertz clock of Tiny Tapeout 2, so the plan was to make a simple controller that would be able to display graphics or text on a rotating fan or something."

Matt Venn's Tiny Tapeout project offers a way for makers to create custom silicon chips, something that would normally cost tens of thousands of dollars, easily and cheaply — by splitting each chip up into multiple project tiles. Balwierz submitted three projects to Tiny Tapeout 2, the second production run, including one that was claimed to be the first Rickroll on a chip.

This second project is somewhat more practical. Working around the restrictions of a Tiny Tapeout project, which place upper limits on clock speed, inputs and outputs, and overall design footprint, Balwierz made a controller capable of driving an eight-LED POV display. "The problem was," the maker explains," in the limited space of a tile on Tiny Tapeout 2 I was only able to fit in about 20 to 30 columns of pixels; that resolution is not high enough to write any text and the graphics would be basic at best."

"So," Balwierz continues, "in the third attempt I decided to combine a fixed character set and graphics. I was able to fit 30 words of seven bits; the highest significant bit would decide if the word represents a column of pixels or a whole character of eight by eight pixels from a character ROM that's on the ASIC itself. [This] ended up being the capital letters, digits, and some commonly-used special characters."

The finished project, which is demonstrated on Balwierz's YouTube channel and in the video embedded above, is capable of delivering a 240×8 display; more information is available on the Tiny Tapeout website, with source code published to GitHub under the permissive Apache 2.0 license.