单片机实训周自己编写的一个RTC时钟。矩阵键盘，闹钟，数码管显示。定时器扫描任务。测试版本，移植前需认真阅读-SCM training weeks of their own to write a RTC clock. Matrix keyboard, alarm clock, digital display. Timer scan task. Test version needs to be carefully read before transplantation