Ultrasonic Distancemeter System Based On MCU

The thesis introduces a kind of single-pulse-reflection ultrasonic distancemeter system in detail based on microcontronller. The system could measure certain distance with the reflected wave on condition in which the speed of transmitting wave is fixed. It generally specifies the theoretical foundation of the system, the electronic design of the ultrasonic sensor. Because the project is the initial part of ultrasonic signal detection based on DSP, it is limited in indoor range in advance. So the design of the system and the choice of the components are decided according to the reason.The scheme of each part is designed to acquire better performance of the system. In order to meet the different distance range, it arranges two transmitting modes in microcontroller: hign gain applies to far mode, while low gain applies to near mode. What is more, it makes use of the integrated chips to simplify the whole configuration, such as ingtegrated filter and programmable gain amplifier, in the optimum receiver that is based on the characters of the receiving waves. And to reduce the rate of misdetection, it carries out the double-threshold detection including amplitude detection and pulse-width detection. Moreover, the Motorola 68HC908GP32 microcontroller is employed in this system to achieve the function of collecting, processing, and displaying of data.This paper summarizes the development and foudamental principle of ultrasonic detection. Then it presents the theory and characters of ultrasonic sensor. At the same time, it discusses a number of main technical parameters. Moreover, it proposes the whole structure of the system by introducing the function of ultrasonic distancemeter. And then the transmission, receiver, detection, display scheme of this distancemeter system is brough out. Specially, after the application of HC08 microcontroller, it analyzes the hardware and software realization of each part in this system. At last the result and error analysis of the experiments is presented.It is proved by experiments that the design of the system is provided with hign accuracy and reliability. In the end, the further measures of modification are presented.