利用单片机的定时器/计数器以查询方式在单片机口线上产生连续周期性矩形波。 利用单片机的定时器/计数器以中断方式在单片机口线上产生连续周期性矩形波。-Use of single-chip timer/counter in query manner on the microcontroller mouth line to produce continuous periodic rectangular wave. Use of single-chip timer/counter interr