#include <Adafruit_NeoPixel.h>

#define PIN 5           // GPIO pin connected to the data input of the LED matrix
#define NUMPIXELS 256   // 8 x 32 = 256 LEDs

Adafruit_NeoPixel strip(NUMPIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  strip.begin();
  strip.show(); // Initialize all pixels to 'off'
}

void loop() {
  rainbowCycle(20);  // Run rainbow cycle animation with 20ms delay per step
}

// Input a value 0 to 255 to get a color value.
// The colours are a transition r - g - b - back to r.
uint32_t Wheel(byte WheelPos) {
  WheelPos = 255 - WheelPos;
  if(WheelPos < 85) {
    return strip.Color(255 - WheelPos * 3, 0, WheelPos * 3);
  }
  if(WheelPos < 170) {
    WheelPos -= 85;
    return strip.Color(0, WheelPos * 3, 255 - WheelPos * 3);
  }
  WheelPos -= 170;
  return strip.Color(WheelPos * 3, 255 - WheelPos * 3, 0);
}

// Draw rainbow that uniformly distributes across all pixels
void rainbowCycle(uint8_t wait) {
  uint16_t i, j;

  for(j=0; j<256; j++) { // cycle all 256 colors in the wheel
    for(i=0; i<strip.numPixels(); i++) {
      // Calculate color for each pixel based on position and cycle step
      strip.setPixelColor(i, Wheel((i * 256 / strip.numPixels() + j) & 255));
    }
    strip.show();
    delay(wait);
  }
}