AD轉(zhuǎn)換芯片ADC0809的原理及應(yīng)用

ADC0809A/D轉(zhuǎn)換芯片的原理及應(yīng)用ADC08098位A/D8組件。它是逐次逼近式A/D（1）ADC0809的內(nèi)部邏輯結(jié)構(gòu)由上圖可知，ADC08098A/D88共用A/DA/D轉(zhuǎn)換完的數(shù)字量，當(dāng)OE（2）．引腳結(jié)構(gòu)IN0－IN7：8條模擬量輸入通道ADC08090－5V，若信號(hào)太小，必須增加采樣保持電路。地址輸入和控制線：4條ALEALE器將行轉(zhuǎn)換。A，B和C為地址輸入線，用于選通IN0－IN7上的一路模擬量輸入。通道選擇表如下表所示。行轉(zhuǎn)換。A，B和C為地址輸入線，用于選通IN0－IN7上的一路模擬量輸入。通道選擇表如下表所示。道000IN0001IN1010IN2011IN3100IN4101IN5110IN6111IN7CBACBA選擇的通ST為轉(zhuǎn)換啟動(dòng)信號(hào)。當(dāng)STEOC為轉(zhuǎn)換結(jié)束信號(hào)。當(dāng)EOCA/DOED7－D0CLK為時(shí)鐘輸入信號(hào)線。因ADC0809500KHZ，VREF（＋），VREF（－）為參考電壓輸入。ADC0809（1）．ADC0809內(nèi)部帶有輸出鎖存器，可以與AT89S51單片機(jī)直接相連。（2）．初始化時(shí)，使ST和OE信號(hào)全為低電平。（3）．送要轉(zhuǎn)換的哪一通道的地址到A，B，C端口上。（4）．在ST100ns（5）．是否轉(zhuǎn)換完畢，我們根據(jù)EOC信號(hào)來判斷。（6）．當(dāng)EOCOE實(shí)驗(yàn)任務(wù)如下圖所示，從ADC0809的通道IN3輸入0－5V之間的模擬量，通過ADC0809轉(zhuǎn)換成數(shù)字量在數(shù)碼管上以十進(jìn)制形成顯示出來。ADC0809的VREF接＋5V電壓。電路原理圖程序設(shè)計(jì)內(nèi)容（1）．進(jìn)行A/D轉(zhuǎn)換時(shí)，采用查詢EOC的標(biāo)志信號(hào)來檢測(cè)A/D數(shù)據(jù)通過P0（2）．進(jìn)行A/DABC＝110ST＝0，ST＝1，ST＝0產(chǎn)生啟動(dòng)轉(zhuǎn)換的正脈沖信號(hào)CHEQU30HDPCNTEQU31HDPBUFEQU33HGDATAEQU32HSTBITP3.0OEBITP3.1EOCBITP3.2ORG00HLJMPSTARTORG0BHLJMPT0XORG30HSTART:MOVCH,#0BCHMOVDPCNT,#00HMOVR1,#DPCNTMOVR7,#5MOVA,#10MOVR0,#DPBUFLOP:MOVINCR0DJNZR7,LOPMOVINCR0MOVINCR0MOV@R0,#00HMOVTMOD,#01HMOVTH0,#(65536-4000)/256MOVTL0,#(65536-4000)MOD256SETBTR0SETBET0SETBEAWT:CLRSETBSTCLRSTWAIT:JNBEOC,WAITSETBOEMOVCLROEMOVMOVB,#100DIVABMOVMOVA,BMOVDIVABMOVMOVSJMPWTT0X:NOPMOVTH0,#(65536-4000)/256MOVTL0,#(65536-4000)MOD256MOVDPTR,#DPCDMOVA,DPCNTADDA,#DPBUFMOVR0,AMOVA,@R0MOVCA,@A+DPTRMOVP1,AMOVDPTR,#DPBTMOVA,DPCNTMOVCA,@A+DPTRMOVP2,AINCDPCNTMOVA,DPCNTCJNEA,#8,NEXTMOVDPCNT,#00HNEXT:RETIDPCD:DB3FH,06H,5BH,4FH,66HDB6DH,7DH,07H,7FH,6FH,00HDPBT:DB0FEH,0FDH,0FBH,0F7HDB0EFH,0DFH,0BFH,07FHENDC<AT89X52.H>unsignedcharcodedispbitcode[]={0xfe,0xfd,0xfb,0xf7,0xef,0xdf,0xbf,0x7f};unsignedcharcodedispcode[]={0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,0x7f,0x6f,0x00};unsignedchardispbuf[8]={10,10,10,10,10,0,0,0};unsignedchardispcount;sbitST=P3^0;sbitOE=P3^1;sbitEOC=P3^2;unsignedcharchannel=0xbc;//IN3unsignedchargetdata;voidmain(void){TMOD=0x01;TH0=(65536-4000)/256;TL0=(65536-4000)%256;TR0=1;ET0=1;EA=1;P3=channel;while(1){ST=0;ST=1;ST=0;while(EOC==0);OE=1;getdata=P0;OE=0;dispbuf[2]=getdata/100;getdata=getdata%10;dispbuf[1]=getdata/10;dispbuf[0]=getdata%10;}}voidt0(void)interrupt1using0{TH0=(65536-4000)/256;TL0=(65536-4000)%256;P1