这是个机于8051单片机的超声波测距程序。工作原理为：

在发射端加一个8--15us的高电平，然后在接收端开始计时，此时接收端为高电平， 超声波在空气中传播一定时间返回接收器，接收端收到一个下降沿，这个过程就是超声波的传输时间，用下面的公式就可以测算出有形物体到测距模块的距离-This is a machine in 8051 ultrasonic ranging process. Working principle: the transmitter plus a 8- 15us' s high, and then start the timer at the receiving end, when the receiver is high, ultrasound propagation in the air some time to return the receiver, the receiver receives a falling, this process is the transmission time of ultrasound, using the following formula can measure the physical distance from the object to the distance measuring module