实现两个单片机之间的串口通信，一个单片机定时用作电子时钟，将时间通过串口送给另一个单片机，收到后从数码管显示时间，且可用按键调整时间-Serial communication between two microcontrollers, a single-chip timing as an electronic clock, the time to give another microcontroller through the serial port, after receiving　the digital display of time, and the available buttons to adjust the time