Design Of Ultrasonic Liquid Level Meter Based On ARM

The liquid Level is the common survey parameter in the industrial production, the chemical industry, the petroleum, the sewage treatment and so on each kind of Manufacturing division must measure liquid Level. At present, the technology of liquid Level Measurement is developing at very fast speed, Large measure, high precision and complete function are characteristic of the new liquid Level meters, our country new liquid Level meters mostly depends upon the import. The ultrasonic liquid level measurement has many merits such as non-contact measurement, low temperature medium measurement, fixed point and continuous measurement. In recent years, the ultrasonic liquid level measuring technique made the considerable progress, it has succeeded applies in the rivers and streams water level, chemistry and the drugs manufacture industry, the food processing, the canned liquid level and so on many kinds of domains.A design of Ultrasonic Liquid Level meter based on ARM is introduced in this thesis. The 8-bit singlechip is used to be processor in conventional ultrasonic liquid Level meters. Generally, the judge of ultrasonic propagation time depend on intermit that ultrasonic echo signal is catched by the electronic component. This thesis bring forward a blue print that using 32-bit ARM chip to make the processor and using the digital signal processing to judge the ultrasonic propagation time.In this thesis, the high-powered LPC2119 chip with ARM7TDMI-S inner core is chosed as the system's CPU, the handling ability of the ultrasonic echo signal is strengthened; ultrasonic echo signal is transformed to digital signal by A/D conversion device, judge the initial station of ultrasonic echo signal depend on digital filter and numerical value process, the precision of liquid level measure is improved; the single transducer monolithic transmit and receive circuit is devised, the liquid Level's computation expressions is predigested; CANBus communication interface is devised by CANBus control unit in LPC2119; digital temperature sensor DS18B20 is adopted as temperature compensation device, the measuring error which produces as a result of ambient temperature's change is avoided. Abundant inner resource and I/O ports in ARM chip are propitious to expand new function and upgrade system. This ultrasonic liquid Level meter can be used conveniently, with high precision. In a word, this Ultrasonic Liquid Level meter can satisfy the need of industrial production.