WS2812B single row scrolling Help needed

Other Hardware LEDs and Multiplexing
1

Hello, I have almost no experience with WS2812b light strips and the only guides I can find are for making multi row scrolling text while I am only looking to use one row. I am currently integrating a WS2812B light strip into a tradeshow display to showcase flow by making the light scroll and change colors at certain points. I have only been able to get a single LED point to scroll using an if statement for the LED # and I will need to have every 6th or so LED scrolling to better show flow.

I am using the fast LED library and my current code is attached.

#include <FastLED.h>

#define LED_PIN     5
#define NUM_LEDS    60
#define LED_TYPE    WS2811
#define COLOR_ORDER GRB
CRGB leds[NUM_LEDS];

#define UPDATES_PER_SECOND 100



void setup() {
 FastLED.addLeds<WS2812B,LED_PIN, GRB> (leds,NUM_LEDS);   
 FastLED.setBrightness(50);


}
void loop(){
  for(int dot = 0; dot <NUM_LEDS; dot++){
    if(dot <= 30){
      leds[dot] = CRGB::Red;
    
    leds[dot+1] = CRGB::Red;
    leds[dot+2] = CRGB::Red;
    //delay(30);
    }
    else if (dot > 30){
    leds[dot] = CRGB::Blue;
    leds[dot+1] = CRGB::Blue;
    leds[dot+2] = CRGB::Blue; 
    //delay(5);
    }
  

    FastLED.show();
    leds[dot] = CRGB::Black;
    leds[dot+1] = CRGB::Black;
    leds[dot+2] = CRGB::Black;
    delay(30);
  }
  }

How would you make this code to run multiple LEDs at a time scrolling in the same direction?

2

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3

Thank You for the info!

4

You write outside the array, never a good idea.

What is that unused wishful-thinking define for?

There are libraries that support matrix setups that include scrolling.

I don't really understand what you want to do, you already scroll three leds.

5

I want to scroll multiple sets of 3 LEDs at the same time but if I set dot =15 after 60 it exits the loop

6

I think what you want is for three out of each 6 LEDs to be RED and the rest to be BLACK. And you want the pattern to shift left. That means there are six different patterns.

#include <FastLED.h>

#define LED_PIN     5
#define NUM_LEDS    60
#define LED_TYPE    WS2811
#define COLOR_ORDER GRB
CRGB leds[NUM_LEDS];

void setup()
{
  FastLED.addLeds<WS2812B, LED_PIN, GRB> (leds, NUM_LEDS);
  FastLED.setBrightness(50);
}

void loop()
{
  // Each of the pattern positions
  for (int shift = 0; shift < 6; shift++)
  {
    for (int dot = 0; dot < NUM_LEDS; dot++)
    {
      if (dot <= 30)
      {
        // Red side
        if (((dot + shift) % 6) < 3) // Three dots of color
          leds[dot] = CRGB::Red;
        else // The rest are black
          leds[dot] = CRGB::Black;

      }
      else // >30
      {
        // Blue side
        if (((dot + shift) % 6) < 3)
          leds[dot] = CRGB::Blue;
        else
          leds[dot] = CRGB::Black;
      }
    }
    // All of the dots are full so show them
    FastLED.show();
    delay(30);  // This sets the rate of motion
  }
}
1 Like
7

That is exactly what I was looking to do except I was hoping to have it go left to right. How would you change the for loop to change direction?

8

The classic way to reverse a 'for' loop is to count down instead of up:

  for (int shift = 5; shift >= 0; shift--)
  {
1 Like
9

Thank You so much for your help!

10

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