System Design Of Displacement Information Remote Monitoring Based On Ultrasonic & Embedded WEB Server

Measuring distance by ultrasonic echoes is an important application in ultrasonic detection field. Its theory and implement are very simple, the best application is it can measure distance without touching the object, so it's suitable to be used in the bad environment. Traditional circuits for ultrasonic measuring are often composed of a MCU(like MCS-51) ,the external analog circuits and digital circuits, the measuring precision is not high, often between 1% -0.5%.Measuring precision lies on the working frequency of MCU, so it's hard to improve it. At the same time this kind of measuring circuits usually display by LCD, they can't monitor in real-time and remotely. Aiming at these shortcomings, this project proposed to use CPLD technology to improve the module of ultrasonic measuring circuits(the realizable precision is millimeter level), and applying embedded WEB server to realize remote monitoring of displacement information. It is effective to improve the capability of system.The project used embedded system as the hardware platform. The embedded microprocessor controlled the CPLD to produce 40kHz square wave and started the counting function of CPLD at the same time. The square wave was amplified in order to drive ultrasonic transmitting transducer. Ultrasonic receiving transducer received the wave signal reflected by the detected object. The signal would be amplified by the following circuits, and then transmitted to microprocessor and CPLD, at this time, the CPLD stop counting. The microprocessor sent a communication handshake signal to CPLD and got the number of pulses that CPLD counted. Then it calculated the distance that the ultrasonic wave gone after the temperature compensation according to the current system temperature. The result data were sent to network through the Ethernet controller of embedded system, so users could get the displacement information that they wanted through computers' WEB browser in any time and any place.This thesis introduces the process of the project in theory analysis, system collectivity design, system hardware circuits design and system software design.