Shawn Maxwell's Compact Hand-Placed RGB LED Matrices Pack the Pixels Into a Tiny, Tileable Board

Maker Shawn "sjm4306" Maxwell has shown off a family of tileable 8x8 RGB LED matrices — built around the compact SK6805, rather than the more common and noticeably larger WS2812 5050.

"I've wanted to make a tiny RGB [LED] matrix that was easy to chain together to form larger displays for quite a while," Maxwell explains of the inspiration behind his project, "and seeing LixieLabs' new Pixie Chroma inspired me to design something similar but at the same time different."

Maxwell began his journey building larger 5x7 LED matrices from the popular WS2812 5050 — a chunky and bright addressable RGB LED which finds its way into a range of projects. "I wanted to make something I could easily solder with my recent meager stenciling and reflow skills," he explains, "and finally debugging a larger board with less components would be far easier than the opposite."

Having built several of the WS2812 boards which confirmed the feasibility of the overall plan — individual matrices which could be tiled along their edge, providing an easy route to expansion — it was time to downscale.

"Now I was comfortable with moving on to the much tinier SK6805-EC15. This really tested my PCB design and layout skills, especially considering I limited myself to double layer and the requirement that the boards had to be soldered side by side with no visible gap," Maxwell explains. "I ended up pushing JLCPCB almost right up to their limits in terms of minimum via and trace dimensions.

"After about a week I had a batch of 10 of the new boards in hand. I also ordered a solder stencil... I'm insane but not the hand solder 64 15mm RGB LEDs kind of insane! And for the most part they looked fine... except I cut very close to the top right edge with a single via which the edge route ate into. I've since modified the board to move the via as close as I could away from the edge so we will see how it turns out next time."

Maxwell built up the ten boards he ordered, and arranged them into a 5x2 matrix-of-matrices — then discovered, while porting a library for printing text to the display, that the ATmega328P used to control the matrix maxed out at 564 LEDs — a little shy of the 640 in the full matrix.

Full details are available on Maxwell's Hackaday.io project page, along with design files for both the large-scale and more compact matrix boards under an unspecified open source license.