Check the clock frequency & that the baud rate required can be achieved. Error of <1 is never a problem, <2 will work but is undesirable, 5 will not work. Note that this assumes that the other end of the link has perfect timing, which will norm

制作PCB时，解决可能出现不能识别汉字、添加任意图案LOGO的问题。(When making PCB, we can solve the problem that can not recognize Chinese characters and add arbitrary pattern LOGO.)