HC-SR04超声波测距模块C51源码，包括1206和12064LCD显示，以及串口输出等，测量距离2cm-400cm，精度可达3mm。-HC-SR04 ultrasonic distance measuring module C51 source, including the 1206 and 12064LCD display and serial output, measure the distance 2cm-400cm, accuracy is up to 3mm.