Serial Port 與Baud Rate的基本知識
https://dotblogs.com.tw/billchung/archive/2012/01/11/65270.aspx
8051Baud Rate的解釋
http://anal02.pixnet.net/blog/post/101596447-%5B8051%E8%A7%80%E5%BF%B5%26code%5D-uart%E8%B3%87%E6%96%99-%E9%AE%91%E7%8E%87%E8%A8%AD%E5%AE%9A
