Abstract：Ultrasonic Ranging, can be used in car reversing, the construction site and the location of some industrial site monitoring, can also be used if the level, depth and length of the pipeline, such as measurement occasions. Measurement of the requirements in the 0.10-5.00 m, precision 1 cm, with the measurement of detected objects without direct contact, being able to clearly show stable measurement results. Because of the strong point of ultrasonic energy consumption slow, medium of communication in the longer distance, thus frequently used ultrasonic distance measurement, such as the range finder and level measurement and so on can be achieved by ultrasound. Use of ultrasonic testing is often more rapid, convenient and simple terms, easy to achieve real-time control, and measurement accuracy can meet the practical requirements of industry, in the mobile robot has been developed on a wide range of applications.
The range finder only NE555 circuit， two amplifier circuit and the level achieved a comparison of launching and receiving ultrasound. SCM range finder for the core elements for launching the circuit control and receive data processing. 10-200 cm in the system of distance measurement accuracy up to ± 0.5cm， and easy to debug， low-cost， with strong practical value and good market prospects.
Keywords: Ultrasonic sensors, range finder, PIC16F876A
