APA102 Module

Since Origin / Contributor Maintainer Source
2016-01-26 Robert Foss Robert Foss apa102.c

This module provides Lua access to APA102 RGB LEDs which are similar in function to the common WS2812 addressable LEDs.

DotStar LEDs are 5050-sized LEDs with an embedded micro controller inside the LED. You can set the color/brightness of each LED to 24-bit color (8 bits each red green and blue). Each LED acts like a shift register, reading incoming color data on the input pins, and then shifting the previous color data out on the output pin. By sending a long string of data, you can control an infinite number of LEDs, just tack on more or cut off unwanted LEDs at the end.

source: Adafruit


Send ABGR data in 8 bits to a APA102 chain.


apa102.write(data_pin, clock_pin, string)


  • data_pin any GPIO pin 0, 1, 2, ...
  • clock_pin any GPIO pin 0, 1, 2, ...
  • string payload to be sent to one or more APA102 LEDs. It should be composed from a ABGR quadruplet per element.
    • A1 the first pixel's Intensity channel (0-31)
    • B1 the first pixel's Blue channel (0-255)
    • G1 the first pixel's Green channel (0-255)
    • R1 the first pixel's Red channel (0-255) ... You can connect a lot of APA102 ...
    • A2, B2, G2, R2 are the next APA102s Intensity, Blue, Green and Red channel parameters



Example 1

a = 31
b = 0
g = 0
r = 255
leds_abgr = string.char(a, b, g, r, a, b, g, r) 
apa102.write(2, 3, leds_abgr) -- turn two APA102s to red, connected to data_pin 2 and clock_pin 3

Example 2

-- set the first 30 leds to red
apa102.write(2, 3, string.char(31, 255, 0, 0):rep(30))