Development Of Physical Experiment Data Acquisition System

Aims at the demand for school physics experiment put forward by the teacher currently,this thesis analyses the software and hardware achievable ways of physics experiment data acquisition system in detail.Briefly including:●The design of software and hardware system structure.●The composition and working principle of the main system hardware.●The software design program related to system function,such as interface display,data storage and the others with PC.●The communications program of each unit.The acquisition system data transports among data acquisition unit-main tank conformity unit-PC conformity display and record unit by USB,I²C main line.Development tools of PC display and conformity interface use the virtual instruments programming environment labwindows/CVI 8.0 comes from the National Instruments Company in the USA.Hardware of acquisition system can be divided into these parts by the signal directions,they are experiment data acquisition unit that ST7FLIT15B1 is the master chip, main tank conformity unit that STM32F103 is the master chip,liquid crystal display unit and PC conformity display and record unit.Experiment data acquisition unit is in charge for detecting the experiment required physical quantity,and provide one simulation quantity data signal between 0～5V,and one I²C digital signal.This unit sensor or related data acquisition circuit carries out data acquisition with the detected physical quantity according to the own design characteristics,and the master chip(ST7FLIT15B1) gets and arranges the physical quantity data which is got from data acquisition module by A/D passage,and sends the received experiment data to main tank conformity unit by simulated I²C main line.The A/D converter reference voltage of ST7FLIT15B1 comes from the supply voltage,so automatic voltage regulator module will make up for the supply voltage,to keep it at 5V,in this way to improve the accuracy of A/D acquisition.Main tank conformity unit is in charge for the arrangement and delivery demand and data between experiment data acquisition unit and PC conformity display and record unit,as well as the display and conformity order of liquid crystal display unit.This unit receives the experiment data acquisition conformity order which comes from PC conformity display and record unit,and sends the order to the corresponding experiment data acquisition unit by simulated I²C main line,and then returns the returned experiment data to PC conformity display and record unit.During the process,the display and conformity order delivery of liquid crystal display unit will be finished at the same time.Liquid crystal display unit is in charged for the system display function of experiment data,while the main tank conformity unit is not connected to PC unit.The menu conformity signal or data display signal of main tank conformity unit sends to liquid crystal display devices by YLF₃12 tft-lcd liquid crystal display controller.In this way it will meet the demand of menu choosing and data display of users.PC conformity display and record unit is in charged for the function of display and storage record of physical experiment data in PC.This unit reads the experiment data by USB,and also adjusts and deals with the data,then displays on PC interface.When the data displays,PC will store the arranged experiment data in the form of Excel file.When users handle on PC interface,it will produce an order and send to main tank conformity unit,and has finished the conformity to hardware.Acquisition system has applied to the physical quantity acquisition of liquid conductivity,temperature,carbon dioxide density and acoustic.The result proves that the acquisition system can meet the requirements of physical quantity acquisition in aspect of function,working stability,reliability,accuracy and so on.At the end of this thesis,there are physical quantity calibration and test results of acquisition system,as well as the further improvement measures.