用P1.0输出1KHz和500Hz的音频信号驱动扬声器，作报警信号，要求1KHz信号响100ms，500Hz信号响200ms,交替进行，P1.7接一开关进行控制，当开关合上响报警信号，当开关断开告警信号停止，编出程序。(Drive the speaker audio signal output of P1.0 1KHz and 500Hz, for the alarm signal, 1KHz signal ring 100ms, 500Hz signal ring 200ms, alternately, P1.7 take control of a switch, when the switch on the sound alarm signal, when switching off alarm signal to stop programs.)