说明：  超声波传感器超声波测距8051汇编源程序 晶振采用6M，P1口为数码管段输出口，P3.0~P3.2为数码管位输出口，P3.5超声波发送输出，P3.7超声波接收。
(Ultrasonic Sensor Ultrasonic Ranging crystal 8051 compilation of source code using 6M, P1 mouth tube sections as a digital output, P3.0 ~ P3.2 for digital tube digital output, P3.5 send ultrasonic output, P3.7 ultrasonic receiver.)