#include <Wire.h>
#include <Adafruit_NeoPixel.h>

#define PIN        5 // Pin to which the Neopixel strip is connected
#define NUMPIXELS  8 // Number of Neopixels in the strip

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

void setup() {
  pixels.begin(); // Initialize the Neopixel strip
  Wire.begin(0x0A); // Slave address
  Wire.onReceive(receiveEvent);
  Serial.begin(9600);
}

void loop() {
  // Nothing to do here
}

void receiveEvent(int howMany) {
  while (Wire.available()) {
    char c = Wire.read();
    if (c == 'N') { // Command to turn on the Neopixels
      for (int i = 0; i < NUMPIXELS; i++) {
        pixels.setPixelColor(i, pixels.Color(0, 150, 0)); // Green
      }
      pixels.show();
    }
  }
}
ESP32
