设计一个数字电子时钟能够准点报时并具有校时功能。
时钟功能: 采用数码管显示累计时间，以24小时为周期。
校时功能: 能快速校准“ 时”、“分”、“ 秒”的功能。
整时报时功能: 具体要求整点前鸣叫5 次低音( 500 Hz ) , 整点时再鸣叫一次高音(1 000 Hz左右) , 共鸣叫6 响, 两次鸣叫间隔0 .5 s。(选做)
计时准确: 每天计时误差不超过10 s。(The design of a digital electronic clock can report time on time and has the function of timing.
Clock function: use digital tube to display the accumulated time, 24 hours as the cycle.
Timing function: it can quickly calibrate the functions of "hour", "minute" and "second".
Timing function: it is specifically required to call 5 times of bass (500 Hz) before the whole point, another high tone (about 1000 Hz) at the whole point, 6 resonance calls, and the interval between two calls is 0.5 s. (optional)
Timing accuracy: the timing error shall not exceed 10 s every day.)