（1）实时显示日期和时间：年、月、日、时、分、秒、星期。该功能用1602芯片实现。

（2）设计的电子时钟具有秒表的功能，该功能用数码管实现：

K3键实现时间显示与秒表的转换；

K2键实现秒表的清零功能；

K1键实现秒表的开始与暂停功能。-(1) Real-time display date and time: year, month, day, hour, minute, second, week. This feature allows the 1602 chip.

(2) design of electronic clock has a stopwatch function that use digital implementation:

K3 key to achieve conversion time display and stopwatch

K2 key to achieve stopwatch clear function

K1 key to achieve the stopwatch start and pause function.