Design Of Thermometer And Hydrometer Based On CAN Bus

As constantly development of our industry manufacture and automation, there is an urgent demand of accurate measurement of the physical element in all sorts of production process. Temperature and humidity are important physical elements in most production process, people pay more attention to their accurate measurement and telecommunication. Therefore, developing a thermometer and hydrometer with high precision, high stability and low cost has tremendous importance, will have extensive market in the near future.This design adopt resonate sensor as its temperature sensor, which is a digital sensor with low cost, high precision, high stability. High precision, high stability, excellent repetition and high anti-jamming ability are its most prominent character. As macromolecule capacitance type of sensor, humidity sensor possesses the traits of completely interconvert, high reliability and long time stability, speedy response.At the same time, because of high requirement of anti-electromagnetism interference and long distance this design uses CAN bus as the communication style of every module. This design uses C8051 as the core to devise the hardware of three modules: the temperature module, humidity module and PC module. And it uses ASM language to develop the software part to handle sensor signals and accomplish the transmitting and receiving of CAN messages.Besides, this instrument also provides the PC software. This software adopts the international popular Visual Basic 6.0 to develop the program. It can display, handle, store the temperature and humidity signals real-timely.At the end of the article, this paper analyses the errors and uses subsection linearization to reduce the error. At last the precision reach the requirement.The thermometer and hydrometer designed mentioned in the article has advantages like low price, high precision, easy operation and long distance. The PC software has advantages like Human-centered Design, friendly interface, easy operation. So this design has wide application prospect and worthy of popularity.