AD7705 application summary（AD7705应用总结）

AD7705applicationsummary（AD7705应用总结）AD7705applicationsummary(AD7705应用总结)AD7705applicationsummary[transfer]:TheYW2314R12projectusesAD7705,whichsummarizestheapplicationexperienceofAD7705andthemainpointsofattentionasfollows:theseexperiencesarealsoapplicabletotheADchipsofADcompanysuchasAD7799andAD7706,whichhavecalibrationfunctions.1.timepoints:whenthedigitalinterfacelostcanlast32pulsecyclesthroughtheADINinput(DCLK)highlevelabovethedigitalinterfaceofAD7705reset,resetafterwaitingmorethan500ustoaccesstheAD7705chip,thisreductiondoesnotaffectanyregisteroftheAD7705department,allregisterswillremainbeforethereturnofthethecontent,butalloftheregistersinthedigitalinterfaceloststatecontentisuncertain,itisstronglyrecommendedthatallinternalAD7705resetregisterafterreset,topreventerrors.TheresetofthechippinRESETwillrestorealltheregistersinthechiptothedefaultvalueofpoweron.TheclockinputsignalDCLKisaSchmidtstartsignalthatisadaptedtotheslowedgeoftheoptocoupler,andtheriseandfalltimesofotherdigitalinputsignalsshouldnotexceed1us.Whenthe2.AD7705clockisgreaterthan2M,theCLKbitoftheclocksettingregistershouldbesetat1,andthe2Mshouldbesetatlessthan0.DCLKpulsewidthtomeettheminimumpulsewidthrequirements.ThedataADOUTisreadduringthelowlevelaftertheclockDCLKdrops.DuringthelowleveloftheclockDCLK,thedataiswrittentotheADIN,andthenwrittentothe7705ontherisingedgeoftheDCLK.WritedataandreaddataofthenumberofclockDCLKand(tobewrittenorreadregisters)numberofthesamelength(moreorlessthanthelengthoftheclockregisterbit)DCLKnumberwillleadtowrongoperation.Inbetweenthetwowriteoperation,ADINshouldbebestkeptathighlevel:becauseany(readorwrite)operationsmuststartfromthewrittencommunicationandwrittencommunicationregisterregister,8bitsofthefirstbitmustbe0,afollow-uptobewrittentothecommunicationsregister.SowhenADINis0,iftheclockDCLKinterferenceledto0writtencommunicationregisters,AD7705willmistakenlythinkiswrittencommunicationoperationregistersstartthe7bitstringwhilewaiting,afterthisinterferencewillleadtothelostofAD7705digitalinterface,whichleadstothecontentsofinternalregistersmaybeunknown.Inaddition,theclocksignalDCLKremainshighbetweenthetwooperationsAD7705.Thatistosay,ADINandDCLKarebestkepthighattheidletimewithoutaccessingtheidletimeoftheAD7705,orbetweenthetwooperations.The3.DRDYsignalisADdataconversionsignaliscompleted,thelowlevelofADsaidduringtheconversioniscomplete,canreadthecontentsofthedataregister,thehighlevelofADsaidduringtheongoingconversion,thendonothaveaccesstothedataregister.Thesameistrueforsystemcalibrationandinternalcalibration.Thelowlevelindicatesthatthecalibrationiscompletedandthatthecontentsofthecalibrationregistercanberead.Thehighlevelindicatesthatthecalibrationisinprogressandthatthecalibrationregistercannotbeaccessedatthistime.ActionscontrarytotheseProvisionsresultunknown.Inaddition,theproceduremustnotputthelogicofDRDYinreverse,otherwisetheresultisunpredictable.4.whetherorcalibrationdataofADconversion,digitalfiltersynchronizationFSYNCaresetto0,sotheAD7705calibrationdataorADconversionworkcanbecarriedout,otherwisethecalibrationandADconversionwillnotbecarriedout,theDRDYsignalisnotlow.WhenFSYNC=0,theDRDYsignalwillbelowafterthecalibrationorADconversioniscompleted,andthecalibrationfactorordataregistercanbereadatthistime.5.theuseofnonbufferedmode,AD7705analoginputfront-endresistance,capacitancechangesintheaccuracyofADconversiongreatly.Ifthesignalsource,temperatureenvironmentanddeviceparameterschangegreatlywhenthesystemisworking,theparametersoftheAD7705analoginputfront-endcircuitareinconsistentwiththeparametersofthesystemcalibration,andtheerrorwillbeverylarge.Buffermodecansolvethisproblemwhenenablingbufferingmode,AD7705betweenanaloginputandADconvertertoaccessaBufferbuffer,sothatAD7705canadapttothefront-endanaloginputimpedance,signalsourcedeviceparameters(resistanceandcapacitance)ofthetemperaturechange,thechangeoftheenvironmentandsystemcalibrationinconsistencies(i.e.thevariationindeviceworkingconditions).So,AD7705calibrationandnormalworkisbestdoneinbufferedmode.6.voltageinputrange:fornonbufferedmode,analoginputsignalrangeisfrom[GND-30mV]to[VDD+30mV].Forbufferedmode,theanaloginputsignalrangeisfrom[GND+50mV]to[VDD-1.5V].7.nonbuffermode,unipolar,gainofGAIN:therangeoftheinvertinginputoftheAD7705isVIN[][]toVDD+30mVVREF/GAINbetweenGND-30mV,whereVREFisthereferencevoltageAD7705.TherangeofthepositiveinputVIN+is[V]to[V+VREF/GAIN].Right,V+andV-mustbegreaterthanGNDandlessthanVDD,whilealsotakingintoaccounttheinputrangeofunipolar,VmustbelessthanVDD+30mVVREF/GAIN,notonlytheanaloginputisV+max=[V+VREF/GAIN]morethanVDD+30mV.8.nonbuffer,bipolar,gainisGAIN:theV+andV-mustbegreaterthanGANandlessthanVDD,VmustbelessthanVDD+30mV-VREF/GAIN,sothattheinputV+max=[V+VREF/GAIN]-notgreaterthanVDD+30mV.ValsomustbegreaterthanGND30mVVREF/GAIN,notonlytheinputV+min=[VVREF/GAIN]--lessthanGND30mV.ThepositiveinputVIN+positivesignalinputrangeis[V]to[V+VREF/GAIN],thepositiveinputVIN+negativesignalinputrangeis[V]to[V-REF/GAIN].Asshownontheright:themaximuminputforwhichV+maxispositive,andV+ministhenegativemaximuminput.The9.buffermode,unipolar,gainofGAIN:attheinvertinginputrangeisbetweenAD7705VIN[GND50mV]to[VDD1.5VVREF/GAIN],whereVREFisthereferencevoltageAD7705.TherangeofthepositiveinputVIN+is[V]to[V+VREF/GAIN].Right,V+andV-mustbegreaterthanGND+50mVandlessthanVDD-1.5V,whilealsotakingintoaccounttheinputrangeofunipolar,ValsomustbelessthanVDD-1.5V-VREF/GAIN,notonlytheinputV+max=[V+VREF/GAIN]morethanVDD-1.5V.The10.buffermode,bipolar,gainofGAIN:attheinvertinginputrangeisbetweenAD7705VIN[GND50mVVREF/GAIN]to[VDD1.5VVREF/GAIN],soasnottoinputVIN+max=[VVREF/GAIN]causedmorethanVINVDD1.5V,inputVINmin=[VVREF/GAIN]--leadingtolessthanVINGND50mV.WhereVREFisthereferencevoltageofAD7705.ThepositiveinputVIN+positivesignalinputrangeis[V]to[V+VREF/GAIN],thepositiveinputVIN+negativesignalinputrangeis[V]to[V-REF/GAIN].Asshownontheright:themaximuminputforwhichV+maxispositive,andV+ministhenegativemaximuminput.#include<reg52.h>#include<absacc.h>#include<intrins.h>#include<math.h>SbitNumber_BIT0=P2^7;SbitNumber_BIT1=P2^6;SbitNumber_BIT2=P2^5;SbitNumber_BIT3=P2^4;SbitBUZZER=P2^3;SbitAD7705_DATA=P3^0;//AD7705input&outputdataSbitAD7705_CLK=P3^1;//AD7705CLKSbitAD7705_DRDY=P1^2;//AD7705datareadySbitAD7705_CS=P1^3;//AD7705CSUnsigned,char,Counter,dis_index,dis_digit;浮t_voltage;unsignedcharmsb_data，lsb_data，temp0，temp1，temp2，来看，temp4，temp5;无符号字符代码display_code[11]=0xa0,0xf9,0xc4,0xd0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff/{，};{0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0xff};虚空Delayms(unsignedcharMS);无效ad7705_start();ad7705_read(无效);无效ad7705_write_reg(unsignedchardata_byte);unsignedcharad7705_read_reg();main(){0x11TMOD=;IT0=1;PCON=0x00;ET0=1;0xfcTh1=;TL1=0x17;tr0=1;EA=1;P0=0xff;P1=0xff;P2=0xf7;P3=0xff;dis_digit=0x77;dis_index=0;计数器,0;ad7705_start();(1){而(ad7705_drdy);ad7705_read();Delayms(50);}}虚空Delayms(unsignedcharMS)/继电器{无符号字符i;而(MS){对于(i=0;i<120;i+);}}无效ad7705_start(){ad7705_write_reg(0x20);ad7705_write_reg(0x0c);ad7705_write_reg(0x10);ad7705_write_reg(0x44);}无效ad7705_read(){ad7705_write_reg(0X38);msb_data=ad7705_read_reg();lsb_data=ad7705_read_reg();t_voltage=(浮动)msb_data;t_voltage=t_voltage*100;t_voltage=t_voltage+(浮动)lsb_data;temp0=t_voltage/100000;temp1=((t_voltage-temp0*100000)/10000);temp2=((t_voltage-temp0*100000-temp1*10000)/1000);术语“=((t_voltage-temp0*100000-temp1*10000-temp2*1000)/100);temp4=(t_voltage-temp0***100000-temp110000-temp21000-temp3*100)/10;temp5=(t_voltage-temp0****100000-temp110000-temp21000-temp3100-temp4×10);}无效ad7705_write_reg(unsignedchardata_byte){未签名字符;ad7705_cs=0;ad7705_clk=1;_nop_();_nop_();对于(i=0;i<8;i+){ad7705_data=(位)(data_byte&0x80);ad7705_clk=0;_nop_();_nop_();_nop_();ad7705_clk=1;data_byte<<=1;}_nop_();ad7705_cs=1;}unsignedcharad7705_read_reg(){我data_readunsignedchar;ad7705_cs=0;ad7705_clk=1;_nop_();对于(i=0;i<8;i+){ad7705_clk=0;_nop_();_nop_();data_read<<=1;data_read|=(char)ad7705_data;_nop_();_nop_();ad7705_clk=1;_nop_();_nop_();}_nop_();ad7705_cs=1;ad7705_drdy=1;返回(data_read);}无效时间(void)中断1{tr0=0;P2=dis_digit;//P2.7——DS8P0=display_code[dis_index];0xfcTH0=;TL0=0x17;计数器+;if(as==1){-_digit=0x77.-_index=temp5.}elseif(as==2){-_digit=0xb7.-_index=temp4.}elseif(as==2){-_digit=0xd7.-_index=temp3.}elseif(as==4){-_digit=0xe7.-_index=temp2.counter=0.}tr0=1;}