超声波测距器,采用AT89C52,12MHz晶振,采用共阳LED显示器。测距范围10cm-5.5m，堆栈在4FH以上，20H用于标志，显示缓冲单元在40H~43H,使用内存44H、45H、46H用于计算距离。-Ultrasonic range-finder, using AT89C52, 12MHz crystal, with a total positive LED display. Distance Range 10cm-5.5m, the stack above the 4FH, 20H for signs, display buffer unit in the 40H ~ 43H, using memory 44H, 45H, 46H used to calculate the distance.