Any tricks to use FastLED with a pre-existing buffer?

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Any tricks to use FastLED with a pre-existing buffer? I’m parsing E1.31 and have a full universe of DMX channel data that I’d like to shove out to some pixels without having to copy or manipulate the data within a CRGB structure. I’m just wanting it to churn out a WS2811 stream from my pre-existing buffer. It’s already in the order that it needs to be sent out and doesn’t need to be manipulated. What’s the easiest way to do this with FastLED? Thanks!

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Assuming that your DMX pixel data is just three-byte clusters of R, G, and B, you can just tell FastLED to use that existing buffer in the addLeds() line. Then just read from DMX, and call FastLED.show() – bam, no copy, no manipulation.

CRGB is unusual for a C++ class in that (1) all the members are PUBLIC, and (2) this kind of low-level messing around is totally supported. See more extensive notes on this here https://github.com/FastLED/FastLED/wiki/Pixel-reference

If you paste a little code showing what how your DMX data buffer is declared, I can (probably!) show you how to set up FastLED to just use it in-place.

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Oh, that’ll make this super simple then. I started throwing together an E1.31 library, mainly for the ESP8266, but added standard Ethernet Shield support today. I figured FastLED would make a good example for the shield, but I currently don’t have one to test. The library is here: GitHub - forkineye/E131: E1.31 (sACN) library for Arduino with ESP8266 support. I’m thinking this is all it would take for a simple E1.31 based pixel driver:

#include <SPI.h>
#include <Ethernet.h>
#include <E131.h>
#include <FastLED.h>

#define NUM_PIXELS 170
#define DATA_PIN 3

byte mac[] = { 0xDE, 0xAD, 0xBE, 0x2F, 0x1E, 0xE3 };

E131 e131;

void setup() {
Serial.begin(115200);
delay(10);

/* Configure via DHCP and listen Unicast on the default port */
e131.begin(mac);

FastLED.addLeds<WS2811, DATA_PIN>((CRGB*)e131.data, NUM_PIXELS);

}

void loop() {
/* Parse a packet and update pixels */
if(e131.parsePacket())
FastLED.show();
}

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Something like that should do it! Let us know how it goes, and if you learning anything of note along the way!