附錄：核心代碼清單#include<reg52.h> //包含頭文件uintvoltdata,realvolt,i,j,k,l,t,sum,a[5]; //定義全局變量ucharadd; //地址變量ucharcodet1[]={"DCVoltmeter:IN"};ucharcodet2[]={"(0~V):.V"};ucharcodet3[]={"Hello!"};ucharcodet4[]={"Welcome!"}; //初始化顯示voiddelay(uintms) //延時(shí)程序{uinti,j;for(i=ms;i>0;i--)for(j=110;j>0;j--);}voidwritelcd_cmd(ucharcmd)//向1602液晶顯示器里寫入命令的函數(shù){en=0;rs=0;rw=0;delay(1);P0=cmd;en=1;delay(1);en=0;}voidwritelcd_dat(uchardat)//向1602液晶顯示器里寫入數(shù)據(jù)的函數(shù){en=0;rs=1;rw=0;delay(1);P0=dat;en=1;delay(1);en=0;}voidlcd_init() //初始化1602液晶顯示器的函數(shù){writelcd_cmd(0x38);delay(5);writelcd_cmd(0x38);delay(5);writelcd_cmd(0x38);writelcd_cmd(0x08);writelcd_cmd(0x01);writelcd_cmd(0x06);writelcd_cmd(0x0c);writelcd_cmd(0x80);}voidaddselect() //量程選擇{switch(add) //判斷地址{case0:adda=0;addb=0;addc=0;break;case1:adda=1;addb=0;addc=1;break;case2:adda=0;addb=1;addc=0;break; //切換到不同的量程default:break;}}uintadtrans() //AD轉(zhuǎn)換{sum=0; //濾波開始for(i=0;i<5;i++) {addselect();ale=1;ale=0;start=1; //啟動(dòng)AD轉(zhuǎn)換。start=0;while(eoc==0); //等待轉(zhuǎn)換結(jié)束。oe=1;a[i]=P1; //出入轉(zhuǎn)換結(jié)果。delay(5); ////每隔5usAD轉(zhuǎn)換并采集一次數(shù)據(jù)，將得到的數(shù)值存入數(shù)組中}for(j=0;j<4;j++) for(i=0;i<4-j;i++)if(a[i]>a[i+1]){t=a[i];a[i]=a[i+1];a[i+1]=t;}for(i=1;i<4;i++){sum+=a[i];} //采用冒泡法比較，取中間3個(gè)數(shù)值voltdata=sum/3;delay(1);oe=0;voltdata=(100*voltdata)/51; //處理運(yùn)算結(jié)果。returnvoltdata;}voiddisvolt() //顯示函數(shù) {ucharsi,san,er,yi; //四個(gè)顯示的位switch(add){case0:realvolt=voltdata;writelcd_cmd(0x80+15);writelcd_dat('1');writelcd_cmd(0xc0+4);writelcd_dat('0');writelcd_dat('5');break; //計(jì)算并顯示對(duì)應(yīng)的電壓值和量程case1:realvolt=voltdata*2.4;writelcd_cmd(0x80+15);writelcd_dat('2');writelcd_cmd(0xc0+4);writelcd_dat('1');writelcd_dat('2');break;case2:realvolt=voltdata*4.8;writelcd_cmd(0x80+15);writelcd_dat('3');writelcd_cmd(0xc0+4);writelcd_dat('2');writelcd_dat('4');break;default:break;}si=realvolt/1000;san=realvolt/100%10;er=realvolt/10%10;yi=realvolt%10; //將電壓值分成4個(gè)一位數(shù)，方便顯示writelcd_cmd(0xc0+9); //顯示電壓值writelcd_dat(si+0x30);writelcd_dat(san+0x30);writelcd_cmd(0xc0+12);writelcd_dat(er+0x30);writelcd_dat(yi+0x30);}voidanjian() //按鍵掃描函數(shù){if(key1==0) //第一個(gè)按鍵按下add=0; //切換檔位elseif(key2==0)add=1;elseif(key3==0)add=2;}voidmain() //主