https://ncrmnt.org/2011/05/25/necromant%e2%80%99s-multidrop-uart-%d1%81%d0%be%d1%84%d1%82%d0%be%d0%b2%d0%b0%d1%8f-%d1%87%d0%b0%d1%81%d1%82%d1%8c/?lang=ru