利用maxplus2完成

1、　　完成带时、分、秒显示的24h计时功能；

2、　　能完成整点报时功能，要求当数字钟的分和秒计数器计到59min52s时，驱动音响电路，四高一低，最后一声高声结束，整点时间到；

3、　　完成对“时”和“分”的校时，并能对秒计数器清零。

-Use maxplus2 completed one complete with hours, minutes, seconds, show 24h time functions　2, can complete the whole point timekeeping function, require that when the digital clock minutes, and seconds counter when the count to 59min52s, driver audio circuit, four high and one low, soon as the end of the last loud, the whole point of time to　3 to complete the " time"　and " sub"　when the school is also able to clear the seconds counter.