Mike Roller Has a Crack at Building the "World's Smallest Blinky LED," Powered by an ATtiny20
Latest 2.4×1.45mm design, as-yet untested, has a real shot at being the smallest programmable LED board ever.
Self-described hacker Mike Roller is taking everyone's first hardware project, the humble blinky LED, to a whole new scale with what he claims to be the world's smallest self-contained blinking LED board.
"I was inspired by previous 'world's smallest blinky' projects to throw my hat in the ring and submit my own attempt," Roller explains of his creation. "My objectives for this project [were] as follows: create the smallest blinky LED circuit — smaller than the current record holder (3.2×2.5mm by mikeselectricstuff); the circuit should be soldered onto a PCB; learn something. This is mostly meant to be an exercise for myself to help develop my fabrication skills and hopefully lead to something that's actually useful."
Roller's design is based around a WLCSP-packaged Microchip ATtiny20 microcontroller, measuring 1.55×1.4mm — the smallest microcontroller the maker was able to find at the time the project started. This is connected to a 0201-footprint red LED with a matching-sized resistor, while a 01005 decoupling capacitor connects to VCC. The largest component: a 220uF tantalum capacitor for power, which measures 3.2×1.6×1mm — and the project's at such a small scale Roller even has to account for the thickness of the laminate layer on the PCB, at 0.3mm.
The finished design, assembled under a stereo microscope and programmed with fine copper wire, was fully-functional — but Roller wanted to go smaller still. A switch to a smaller capacitor and a 01005-footprint LED shrunk the footprint of the board, and dropping the decoupling capacitor — not required while running the microcontroller at a sedate 128kHz — reduced the bill of materials too. The result: a self-contained programmable blinky that comes in at a mere 2.4×1.45mm.
More details on both designs are available on Roller's Hackaday.io page; while the first design has been assembled and tested, the smaller second design was awaiting assembly at the time of writing.