Technical Retrospective on Controlling Addressable Christmas Lights

The video from the Computerphile channel presents a technical retrospective on controlling addressable Christmas lights, comparing a 2014 solution (Raspberry Pi with individual wiring) to a modern approach using addressable LEDs (WS2811). The current system relies on three wires (5V power, ground, and a single data wire) to control up to 2000 LEDs in series. Each LED reads the first 24 bits (encoding RGB in hexadecimal) to define its color, then transmits the subsequent bits to the next LED. The transmission uses a serial protocol with time modulation: a "0" is encoded by a short high pulse (0.5 µs) followed by a long low pulse (2 µs), and a "1" by a long high pulse (1.2 µs) and a short low pulse (1.3 µs). A prolonged low pulse (>50 µs) resets all LEDs. Brightness is adjusted via Pulse Width Modulation (PWM). In case of an LED failure, the chain is interrupted, similar to traditional light strings.