测频仪51程序和仿真，可测频率范围为20-100k，精度0.01%F.s

/************************************************************************************************* * FUNCTION NAME:Detection of Faint Signal On Vibrating Wire Sensors * *`CREATE DATE :2010.4.23 * * CREATED BY :Liu Haijun ,Haohua * * MODEIFY DATE :2010.4.27 * * INPUT :20Hz TO 50kHz * * OUTPUT :100Hz TO 10kHz * * SUPPLY :8 TO 12VDC * * CRYSTAL :33MHz * * *************************************************************************************************/ #include<reg51.h> #include<stdio.h> #include<lcd.c> #include<math.h> #include<intrins.h> void DelayL( ); void DelayS( ); sbit p32=P3^2; sbit p10=P1^0; sbit p17=P1^7; void main( void ) { unsigned long int period=1196,k=1,n,c=0,pp1; float f=0,m,q;//设定初始频率为振弦固有频率 char buff[30]; int l1,l2; p17=0x00; p10=0x00; P2=0x00; //分频器起始为不分频，每加1则递增16分频 delay(); init_LCD(); //显示设备复位 lcdprintf(0,0," Vibrating Wire "); lcdprintf(0,1," Sensors Tester "); n=2227;//延时显示设备型号5s while(n--) delay(); clr_lcd(); delay(); //清屏延时 delay(); lcdprintf(0,0,"Frequency is: "); lcdprintf(14,1,"Hz"); while(1) { TR0=1; n=0; TMOD=0X01; p17=1; //关闭T0输入口 l1=(65536-period/2/k+55)/256;//将上次的周期赋值给定时器，使用上次的周期激振振弦 l2=(65536-period/2/k+55)%256;//51为其余运算延迟时间 n=1500000/(period/2/k-55);//激振150ms TR0=1; while(n--) { TH0=l1; TL0=l2; while(!TF0); //等待周期完成 p10=~p10; TF0=0; } p10=0; TR0=0; n=0; p17=0; //打开T0输入口 while(n<=1)//测量2次 { n++; f=0;//清除上次保存的频率 pp1=0; TMOD=0X09; TH0=0X00; TL0=0X00; while(p32==1); TR0=1; while(p32==0); while(p32==1); while(p32==0); TR0=0; period=(TH0*256+TL0)*2; //一个周期所用时间,33MHz晶振 while(period<=2500) /*判断是否需要增加分频*/ { P2++; c++; period*=16; } k=pow(16,c); /* 分频的i次方*/ f=(1000000.0/(1*period))*k; for(q=f;q>=1;q=q/10) //计算f的小数点以前的位数 pp1++; pp1+=4;//加上小数点和后三位 if(f<1000) { lcdprintf(13,1," ");//消除频率有1K减小到几百时的K字符 sprintf(buff,"%4.3f",f); for(;pp1<=10;pp1++) //消除多余字符 lcdprintf(pp1,1," "); } else { lcdprintf(13,1,"k");//当频率增加到K以上时，将单位由Hz变为KHz m=f/1000.0; sprintf(buff,"%4.3f",m); for(pp1-=3;pp1<=10;pp1++) //消除多余字符 lcdprintf(pp1,1," "); } lcdprintf(0,1,buff); while(period>=40010)//判断是否减小分频 {P2--; c--; period=period/16; } if(P2>=0x04)//判断是否为零频率 { P2=0x00; c=0; } } } }