Addressable RGB

Taking a closer look at the PWM behavior of the WS2812: Why does it have 11 bit PWM resolution when only 8 bits are used for color data?

Reverse-engineers a whole-wire LED Christmas string that encodes data on the supply rails, mapping its protocol.

What would it take to build an addressable LED like the WS2812 (aka Neopixel) using only discrete transistors? Time for a small “1960 style logic meets modern application” technology fusion project.

Whenever a logic gate in an integrated circuit switches, it will cause a tiny current spike that can be measured in the supply current. By inspecting the temporal variation it is often possible to deduce information about the construction of the IC. Let’s take a closer look at the WS2812 RGB LED.

Builds an addressable seven-segment display module using Padauk MCUs, covering protocol details and firmware.

Analyzing the SK9822 addressable RGB-LED, a clone of the SPI based APA102.

Analyzing a new addressable RGB LED: The SK6812.

Dissects APA102 timing details to explain start frames, data forwarding, and reliable end-frame clocking.

How to estimate WS2812 string length by measuring supply-voltage sag from the LEDs’ current draw.

Investigating the SPI based the APA102/APA102C LED, outlining its SPI protocol, global brightness control, and fast PWM behavior.

Implementing a stripped down version of V-USB including a WS2812 controller on a minimal ATtiny10 MCUs with only 1kb of flash.

Implementation of the optimized light_ws2812 driver with hand crafted assembly inner loop that bit-bangs LEDs even at 4 MHz without timing violations on an AVR.

Analyzing and understanding the WS2812 timing, protocol tolerances, and hardware behavior to enable a reliable driver implementation.