串口通信，实现波特率1200，收/发时钟频率与波特率之比为16，实现与PC机的通信。-Serial communication, to achieve baud rate 1200, T/R ratio of clock frequency and the baud rate of 16 to achieve the communication with the PC machine.

串口时钟。实现向串口发送实时时钟数据。时间可以随时校准-Serial clock. Send real-time data to achieve the serial clock. Time can always calibrate