Fire String

Capture that cozy, hypnotic feeling of watching embers glow and fade late in the evening. This is a string of 300 RGB LEDs driven by a custom RP2040 board running a real-time ember simulation. Not a looping animation or a flickering light on a timer, but an actual physics-inspired simulation where each LED has its own temperature, flares up independently, shares heat with its neighbours, and slowly cools back down. The result is an organic, never-repeating glow that looks surprisingly convincing piled up in an unused fireplace, draped in a jar, or arranged however you like.

I originally built this for my own living room after getting rid of the unconvincing electric heater that came with our blocked-up fireplace. It's been running every evening for months now and my partner has started switching it on unprompted - which I take as the highest possible endorsement. I had a small batch of boards made and have a few spare, so here they are. You can read the full story of how it was designed and built on my blog, and the firmware and hardware files are available on github if you want to tinker.

Powered via USB-C. The controller works out of the box. Switch presets and create your own configurations by plugging it into the computer and opening the small onboard html file. Alternatively you can reprogram it yourself using micropython.