设计一个年误差在毫秒级、免校对的数字钟，要求带有时分秒显示、掉电时时钟正常运行、免校对。

选做：增加报时功能，日报时点数最大100点，报时点掉电不丢失，并可冬夏季报时时间自动切换，各报时点报时时间可控。

-Design error in a millisecond years, free proof of the digital clock, minutes and seconds required with a display, power-down when the clock is running, free proof. Optional: add repeater function, when the daily maximum 100 points and a time-point non-volatile, and can automatically switch the time when winter quarterly, the timekeeping timekeeping time control point.