The BLM Badge comes with six side-lit NeoPixel LEDs around the edge of the board. These RGB NeoPixel LEDs can be used to create all the colors of the rainbow and everything in between. The following example displays a flowing rainbow across all the LEDs.


You'll need to install one library in Arduino for this example to work. Open the Arduino IDE. Click Arduino > Sketch > Include library... > Manage Libraries, then type 'neopixel' in the search box. Install the library shown here.


In the Arduino IDE, create a new sketch by clicking  File > New

Then, copy the code shown below and paste it into the new sketch.

#include <Adafruit_NeoPixel.h>

#define LED_COUNT 6

Adafruit_NeoPixel strip(LED_COUNT, LED_PIN, NEO_GRB + NEO_KHZ800);

void setup() {

void loop() {

void rainbow(int wait) {
  for(long firstPixelHue = 0; firstPixelHue < 5*65536; firstPixelHue += 256) {
    for(int i=0; i<strip.numPixels(); i++) { 
      int pixelHue = firstPixelHue + (i * 65536L / strip.numPixels());
      strip.setPixelColor(i, strip.gamma32(strip.ColorHSV(pixelHue)));


First you include the NeoPixel library you installed.

Next, you tell the code you have 6 NeoPixels, and the pin they are on. Then, you declare the NeoPixel object using the info you provided.

In setup, you initialise the NeoPixel strip object, make sure the LEDs begin turned off, and set the brightness to approximately 1/5 maximum (max is 255). These LEDs are really bright at max!

In the loop, we run the rainbow code with a 10ms delay. Increase this number to slow down the rainbow.

Finally, we have the rainbow code, which requires you to provide a wait time in milliseconds.

That's all there is to making NeoPixel rainbows with Arduino and the BLM badge!

This guide was first published on Mar 24, 2021. It was last updated on Jul 24, 2024.

This page (Arduino NeoPixel Rainbow) was last updated on Mar 08, 2024.

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