Research And Design Of Intelligent Temperature Transmitter Based On FPGA

The emergence of the intelligent instruments has greatly improved the traditionalinstrument in performance and application scope,and widely used on various fields.In theindustrial control area,The temperature is one of the indispensable and the most importantmeasurement parameters, on the scene,most of the equipment can’t be reliable and stableoperation without the monitor and control of the temperature.The temperature transmitter is atemperature acquisition instrument that can convert the temperature signals into standardcurrent signal and has the function of bus communication,the key point of research anddevelopment of the temperature transmitter is that it can be reliable、accurate and intelligentoperation.This paper expounds the commonly working principle of intelligent instruments,andanalyzes and studies the advantages and disadvantages of the traditional DSP and SCMintelligent temperature transmitter scheme.It found the status that it is contradictory betweenstorage space and data processing speed，and some other deficiencies.Based on this it presentsthe design scheme and advantages of intelligent temperature transmitter based on Nios Ⅱ.This paper detailedly introduces this scheme by three aspects: hardware, SOPCtechnology and software system.This transmitter has the function that it can accept varioustypes of RTD,Thermocouple and millivolt signals,it can compensate the cold end of theThermocouple,adjust the input and output signals,it can detech the status of signals and set theinternal parameters by PC.This scheme uses the characteristics of SOPC technology,and usesthe internal hardware logic resources of FPGA to achieve the processor and various peripheralcontroller and interface. And it also uses the function of Nios Ⅱ custom instructions to customthe module of linear interpolation of temperature and median filter.Compared with thetraditional scheme of SCM and DSP,this intelligent temperature transmitter has theadvantages that it has data processing speed quickly,smaller storage space,reasonable resourceconfiguration, and shorter development period.At last, in order to compare the queryingmethod、floating-point calculation method、linear interpolation method achieved by softwareand linear interpolation method achieved by hardware,it is verified by four aspects: storagespace、linear speed、system resources utilization and system precision.In the end of thispaper,the further work of the intelligent temperature transmitter is summarized and discussed.