// cheap printf from https://forum.arduino.cc/t/easy-way-of-doing-printf/369075

void setup()
{
  Serial.begin(115200);
  fdevopen (putChar, getChar); // See https://forum.arduino.cc/t/easy-way-of-doing-printf/369075/20
  printf("0x%04X %02d:%02d:%02d.%06d\n",-1,1,2,3,micros());
}

void loop()
{
}

// See https://forum.arduino.cc/t/easy-way-of-doing-printf/369075
int getChar (FILE *fp)
{
    while (!(Serial.available()));
    return (Serial.read());
}

int putChar (char c, FILE *fp)
{
    if (c == '\n') {
        putChar ((char) '\r', fp);
    }
    Serial.write (c);
    return 0;
}