Using NFC tags to change RGB LED colours

/*
  Copyright 2023 Tauno Erik
  Started: 07.10.2023
  RC522 module
 */
#include <Arduino.h>
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_PN532.h>
#include <Adafruit_NeoPixel.h>

// pins for SPI communication.
#define PN532_SCK    SCK
#define PN532_MOSI   MOSI
#define PN532_SS     SS
#define PN532_MISO   MISO
#define PN532_IRQ    22
#define PN532_RESET  21

Adafruit_PN532 nfc(PN532_SCK, PN532_MISO, PN532_MOSI, PN532_SS);

const int RGB_PIN = 2;
const int NUMPIXELS = 6;
Adafruit_NeoPixel pixels(NUMPIXELS, RGB_PIN, NEO_GRB + NEO_KHZ800);

int counter = 0;
uint8_t green_tag[7] = { 0x1D, 0xDE, 0xBC, 0xDC, 0x93, 0x00, 0x00 };
uint8_t   red_tag[7] = { 0x1D, 0x26, 0xBD, 0xDC, 0x93, 0x00, 0x00 };

const uint32_t OFF = pixels.Color(0, 0, 0);
const uint32_t GREEN = pixels.Color(0, 150, 0);
const uint32_t BLUE = pixels.Color(0, 0, 150);
const uint32_t RED = pixels.Color(150, 0, 0);

uint32_t pixels_colors[NUMPIXELS] = {OFF};

/*
Compare the two arrays
*/
bool is_equal(uint8_t array1[], uint8_t array2[]) {
  bool result = true;

  for (uint8_t i = 0; i < sizeof(array1); i++) {
    if (array1[i] != array2[i]) {
      result = false;
      break;
    }
  }
  return result;
}

void add_color(uint32_t new_color) {
  // move elemnts to right one step
  for (int i = NUMPIXELS; i > 0; i--) {
    pixels_colors[i] = pixels_colors[i-1];
  }
  pixels_colors[0] = new_color;
}

void setup(void) {
  Serial.begin(115200);
  /*
  while (!Serial) {
    delay(10);
  }
  */
  Serial.println("Hello!");

  pixels.begin();
  pixels.show();             // Turn OFF all pixels ASAP
  pixels.setBrightness(50);  // Set BRIGHTNESS to about 1/5 (max = 255)

  nfc.begin();

  uint32_t versiondata = nfc.getFirmwareVersion();

  if (!versiondata) {
    Serial.print("Didn't find PN53x board");
    while (1) {
      // halt
    }
  }

  // Got ok data, print it out!
  Serial.print("Found chip PN5");
  Serial.println((versiondata>>24) & 0xFF, HEX);
  Serial.print("Firmware ver. ");
  Serial.print((versiondata>>16) & 0xFF, DEC);
  Serial.print('.');
  Serial.println((versiondata>>8) & 0xFF, DEC);

  // Set the max number of retry attempts to read from a card
  // This prevents us from waiting forever for a card, which is
  // the default behaviour of the PN532.
  nfc.setPassiveActivationRetries(0xFF);

  Serial.println("Waiting for an ISO14443A card");
}

void loop(void) {
  pixels.clear();  // Set all pixel colors to 'off'
  boolean success;

  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };  // Buffer to store the returned UID
  // 4 or 7 bytes depending on ISO14443A card type
  // ntag 7 bytes
  uint8_t uid_length;

  // Wait for an ISO14443A type cards (Mifare, etc.).  When one is found
  // 'uid' will be populated with the UID, and uidLength will indicate
  // if the uid is 4 bytes (Mifare Classic) or 7 bytes (Mifare Ultralight)
  success = nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, &uid[0], &uid_length);

  if (counter > NUMPIXELS) {
    counter = 0;
  }

  if (success) {
    Serial.println("Found a card!");
    Serial.print("UID Length: ");
    Serial.print(uid_length, DEC);
    Serial.println(" bytes");

    Serial.print("UID Value: ");
    for (uint8_t i=0; i < uid_length; i++) {
      Serial.print(" 0x");
      Serial.print(uid[i], HEX);
    }
    Serial.println("");

    if (is_equal(green_tag, uid) && uid_length == 7) {
      Serial.println("green tag");
      add_color(GREEN);
    } else if (is_equal(red_tag, uid) && uid_length == 7) {
      Serial.println("red tag");
      add_color(RED);
    } else {
      Serial.println("unknown tag");
      add_color(OFF);
    }


    counter++;
    for (int i = 0; i < NUMPIXELS; i++) {
      pixels.setPixelColor(i, pixels_colors[i]);
    }
    pixels.show();
    delay(500);  // slowdown

  } else {
    // PN532 probably timed out waiting for a card
    // Serial.println("Timed out waiting for a card");
    Serial.println("---");
  }
}