constexpr char ae = -26; //   xE6 \u00E6
constexpr char oe = -8;  //   xF8 \u00F8
constexpr char aa = -27; //   xE5 \u00E5

const char str[] = "æøåÆØÅ";
char buffer[64] = { '\0' };
char hex_str[2];

unsigned char hex[3] = { 0x00 };

// -------------------------------------------------

char* hex2char(unsigned char x, char hex[] = hex_str) {
  hex[0] = (char)x;
  hex[1] = '\0';
  return hex;
}
// -------------------------------------------------

void setup() {
  // put your setup code here, to run once:
  Serial1.begin(115200);
  Serial1.println("");

  unsigned char x = (unsigned char)str[0];
  const char* hx = hex2char(x);

  Serial1.println(x);
  Serial1.println(hx);


  /*
  Serial1.println(ae);  
  char newChar = 'æ';
  Serial1.println((int8_t)newChar); // Prints: -26
  Serial1.println((int)newChar);
  while (1);
  */

  /*
  int mod = 0;

  buffer[0] = '\0';

  for (int i=0; i<strlen(str); i++) {
    int16_t x = str[i];
    uint8_t hi = x & 0xF0;
    uint8_t lo = x & 0x0F;
    Serial1.print((char)x); Serial1.print(" -> 0x");
    Serial1.print(hi,HEX);  Serial1.print(",0x");
    Serial1.println(lo,HEX);
  }
  */

}

void loop() {
  delay(1); // this speeds up the simulation
}