Design And Implementation Of Portable High Precision Thermometer

With the development of the science and technology era,each industry must make corresponding changes to meet the changes of the times and the needs of the market,which is not only the difficulties facing the industry but also the driving force for the development of the industry.In industrial control,temperature detection is a particularly important monitoring index,especially in the high standard and innovative industries,this demand is particularly urgent.Platinum resistance thermometers are common in high-precision temperature measurement.The purpose of this paper is to develop a low-cost and high-performance temperature measurement system based on electronic technology,computer technology,and microelectronics technology.According to the index requirements,the work in the fields of metrology,meteorology,and scientific research is carried out to meet the requirements of precise temperature measurement and calibration.Firstly,the paper expounds on the practical significance of the research.Secondly,when platinum resistors are used for mid-temperature range measurement,it is important to solve the problem of non-linearity of the resistance-temperature characteristic relationship of platinum resistors and the problem of zero drift caused by temperature changes.A 1m A high-precision constant current source is designed to reduce noise;the four-wire wiring method of a multi-channel temperature sensor is used to measure the signal to realize signal acquisition;the small-signal collected is processed by a low-noise amplifier,and the analog value of voltage is converted into digital value through 24-bit analog-to-digital converter after 26 times amplification;to obtain more stable voltage data,we sample the voltage To improve the stability of measurement and reduce the influence of drift,the standard resistance with low-temperature drift(?)and high precision(0.1%)is used for timing self-calibration;to reduce the nonlinear problem in a wide range of temperature measurement,the temperature quadratic equation is solved to calculate thetemperature value.The control core chip STC8F2K64S4 is selected to be responsible for the calculation of the overall design.A lithium battery is used to separate the main control part from the signal acquisition part.The instrument is equipped with a simple keyboard to make the instrument easy to use;the instrument is equipped with an OLED liquid crystal display to make the instrument convenient for users to observe.The designed real-time clock can flexibly adjust the upload rate and time interval.Finally,the whole system prototype is debugged.After the test,it is concluded that the prototype can realize two-way temperature measurement.When the temperature measurement range is from-20 ℃ to 200 ℃,the measurement accuracy of the prototype reaches ± 0.02 ℃,the display resolution reaches 0.001 ℃,and the display stability reaches the last digit changes within two digits,which can meet the high-precision measurement.