用8051控制报警产生实例

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。-control with 8,051 police have used examples of P1.0 1KHz and 500Hz output audio signal Flooding dynamic loudspeakers for alarm signal, a request KHz signal ring for 100 ms, 500Hz signal ring for 200 ms. alternating, then a switch P1.7 control, a switch off the alarm signal, when the switch disconnected warning signal to stop, write procedures.