An ATtiny85 "Hello World" PCB Blinkie

For quite some time I've been curious about printed circuit boards, and with this 5-LED ATtiny85 blinker I finally designed and ordered my own. This comes many months after taking a class on the open source KiCAD EDA suite used.

If you're interested in — whether you take a class or not — my advice would be to "just go for it" and design and order your own PCB. You'll probably make a mistake or two — like the improper battery footprint on my layout — but knowing that you can actually make such a board is a really empowering experience. You might even think of it like printing out "hello world" in a new computer language.

The process, however, does seem to be a bit addicting. I've ordered a second board since then, have a third in the works, and have already been contemplating on whether or not I should take the leap from through-hole to surface-mount components.

As for the the board itself, each simply routes the five available ATtiny85 IO pins through resistors to LEDs. The reset button is used as an input, and each chip is programmed to go through a routine on powerup, then go to sleep again. These routines, found on GitHub, include a line of LEDs traveling from one end to the other, an expanding "blink" mode meant for bicycle use, and a simulated-candle with only three LEDs — white, yellow, and red. The candle doesn't work nearly as well as I'd imagined, but the other two are quite beautiful, as seen in the video above.