Hey there! In the past I've had multiple pins with varying lengths of LEDs

Tim_Lukasik · June 1, 2018, 3:36am

Hey there! In the past I’ve had multiple pins with varying lengths of LEDs which I was then able to put into a multidimensional array like this:

CRGB leds[NUM_STRIPS][NUM_LEDS0 + NUM_LEDS1 + NUM_LEDS2 + NUM_LEDS3 + NUM_LEDS4 + NUM_LEDS5];

FastLED.addLeds<LED_TYPE, 6>(leds[0], NUM_LEDS0);
FastLED.addLeds<LED_TYPE, 9>(leds[1], NUM_LEDS1);
FastLED.addLeds<LED_TYPE, 10>(leds[2], NUM_LEDS2);
FastLED.addLeds<LED_TYPE, 11>(leds[3], NUM_LEDS3);
FastLED.addLeds<LED_TYPE, 12>(leds[4], NUM_LEDS4);
FastLED.addLeds<LED_TYPE, 13>(leds[5], NUM_LEDS5);

I was able to tell all of the strips to display rainbow() for example all at the same time and the pattern worked for the length of the strip.

Now, I have the opposite - I have one long strip that I want to break down into multiple “virtual” strips. For example, 75 total LEDS on a single physical strip/pin but I want to be able to break that down into 5 @ 10 LEDs and 5 @ 5 LEDs (total 75). The pattern would be 10 - 5 -10 - 5 - 10 -5 - 10 - 5 - 10 - 5. I might want to fill each of the 5 length virtual strips with blue while I make the 10 length virtual strips do rainbow.

I’m sure there’s a way to do this, any pointers?

marmil · June 1, 2018, 8:21am

One way would be to use RGBSet.

Two basic examples:

github.com

marmilicious/FastLED_examples/blob/master/CRGBSet_example.ino

// Marc Miller, Jan 2016

#include "FastLED.h"
#define NUM_LEDS 32

//CRGB leds[NUM_LEDS];  // Not using this.  Using CRGBArray instead.
CRGBArray<NUM_LEDS> leds;

CRGBSet partA(leds(6,9));  // Define custom pixel range with a name.
CRGBSet partB(leds(22,25));  // Define custom pixel range with a name.

CHSV colorOne(0,222,255);  // Define a custom color.
CHSV colorTwo(82,222,255);  // Define a custom color.

//---------------------------------------------------------------
void setup() { 
  FastLED.addLeds<LPD8806, 11, 13, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(255);
}

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github.com

marmilicious/FastLED_examples/blob/master/CRGBSet_example2.ino

// Marc Miller, Oct 2017

#include "FastLED.h"
#define NUM_LEDS 32

//CRGB leds[NUM_LEDS];  // Not using this.  Using CRGBArray instead.
CRGBArray<NUM_LEDS> leds;

CRGBSet partA(leds(0,NUM_LEDS/2-1));  // First half of strip.
CRGBSet partB(leds(NUM_LEDS/2,NUM_LEDS-1));  // Second half of strip.


//---------------------------------------------------------------
void setup() { 
  delay(500);
  FastLED.addLeds<LPD8806, 11, 13, GRB>(leds, NUM_LEDS);
  FastLED.setBrightness(255);
}

//---------------------------------------------------------------

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Another option you could try would be adding two temp led arrays that you keep modifying stuff in and then copying that data to the leds that actually get displayed. So you might have something like:
#define NUM_LEDS 75
#define sizeA 10
#define sizeB 5

CRGB leds[NUM_LEDS];
CRGB tempA[sizeA]; //working temp array of 10 pixels
CRGB tempB[sizeB]; //working temp array of 5 pixels

Then you could do something like:
fill_rainbow( tempA, sizeA, millis()/20 );
fill_solid( tempB, sizeB, CRGB::Blue );

Then have a subroutine that could copy tempA and tempB data to each of the appropriate sections before calling FastLED.show().

Or you might skip using the temp arrays all together and just operate directly on the beginning of the single long strip. Since you seem to have 15 pixels (10 + 5) that repeat 5 times (for a total of 75), you could also do something like:

#define NUM_LEDS 75
#define sizeA 10
#define sizeB 5

CRGB leds[NUM_LEDS];

fill_rainbow( leds, sizeA, millis()/20 ); //only fills 10 pixels
fill_solid( &(leds[sizeA]), sizeB, CRGB::Blue ) //start at pixel 10, filling 5 pixels
Then use a for loop and copy 15 pixels at a time four times to the rest of the leds array. Or if using RGBSet (with each set being 15 pixels long) you could do:
partB = partA;
partC = partA;
partD = partA;
partE = partA;

Tim_Lukasik · June 2, 2018, 1:39am

Thank you so much @marmil for your fast response, this is exactly what I’m looking for. I think I’m going to use the CRGBSet with partA through partWhatever. This is going to be used in a hat creation of mine for a summer concert at the beach so its not going to be in a Top Hat. The luxury of the Top Hat is lots of room inside for wiring, this hat doesn’t have that so I wanted to minimize the wiring as much as possible to keep it clean looking.

Thanks again and pics will be posted once competed