#include <Adafruit_NeoPixel.h>

#define PIN 2
#define NUM_PIXELS 256

Adafruit_NeoPixel pixels = Adafruit_NeoPixel(NUM_PIXELS, PIN, NEO_GRB + NEO_KHZ800);

void setup() {
  pixels.begin();
}

void loop() {
  displayRows();
  displayColumns();
}

void displayRows() {
  for (int row = 0; row < 16; row++) {
    uint32_t color = randomColor();
    for (int col = 0; col < 16; col++) {
      pixels.setPixelColor(row * 16 + col, color);
    }
    pixels.show();
    delay(100);
  }
}

void displayColumns() {
  for (int col = 0; col < 16; col++) {
    uint32_t color = randomColor();
    for (int row = 0; row < 16; row++) {
      pixels.setPixelColor(row * 16 + col, color);
    }
    pixels.show();
    delay(100);
  }
}

uint32_t randomColor() {
  return pixels.Color(random(256), random(256), random(256));
}