Write BYTES to MIFARE without trancoding to ASCII-HEX

Projects Programming
3

I am not clear what you want to do with the output but consider something like this method

char source[] = {"d73f7a79"};

void setup()
{
  Serial.begin(115200);
  static char output[3];  //zero in all elements
  for (int offset = 0; offset < 4; offset++)
  {
    memcpy(output, source + (2 * offset), 2);
    int value = strtol(output, 0, 16);
    Serial.print(output);
    Serial.print("\t");
    Serial.println(value);
  }
}

void loop()
{
}