void DecToHex(long Value, int noOfBytes) {
  char buf0[5];
  char buf1[5];
  char format[] = "%0.4X";
  if (noOfBytes < 2) {
    format[3] = '2';
  }
  sprintf(buf0, format, Value);
  if (noOfBytes > 2) {
    sprintf(buf1, format, Value >> 16);
    Serial.print(buf1);
  }
  Serial.println(buf0);
}

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.println("Start");
  byte x = 0xFF123456;
  DecToHex(x, sizeof(x));
  int y = 0xFF123456;
  DecToHex(y, sizeof(y));
  long z = 0xFF123456;
  DecToHex(z, sizeof(z));
}


void loop() {
  // put your main code here, to run repeatedly:
}