void dispBytes(const char *s)
{
  int len = strlen(s);

  for(int n = 0; n < len; n++)  {
    if(s[n] <= '9') {
      Serial.write(s[n] - '0');
    }
    else if(s[n] >= 'a') {
      Serial.write(s[n] - 'a' + 10);
    }
    else {
      Serial.write(s[n] - 'A' + 10);
    }
  }
  Serial.println();
}


// -----------------------------------------------------------------------------
void setup()
{
  Serial.begin(9600);

  String numbers  = "0123456";
  dispBytes(numbers.c_str());

  Serial.write(0x00);
  Serial.write(0x01);
  Serial.write(0x02);
  Serial.write(0x03);
  Serial.write(0x04);
  Serial.write(0x05);
  Serial.write(0x06);
  Serial.println();

  numbers  = "abcdef";
  dispBytes(numbers.c_str());
  Serial.write(0x0a);
  Serial.write(0x0b);
  Serial.write(0x0c);
  Serial.write(0x0d);
  Serial.write(0x0e);
  Serial.write(0x0f);
  Serial.println();

  numbers  = "ABCDEF";
  dispBytes(numbers.c_str());
  Serial.write(0x0A);
  Serial.write(0x0B);
  Serial.write(0x0C);
  Serial.write(0x0D);
  Serial.write(0x0E);
  Serial.write(0x0F);
}

void loop()
{
}