我做的滤波器
#include<reg51.h>
#include"math.h"
#define N 25
#define PI 3.1415926
sbit da_wr1=P3^6;
sbit da_cs=P2^7;
void InputWave();
float FIR();
void da0832();
float fHn[N]={0.0,0.0,0.001,-0.002,0.01,-0.09,
-0.018,0.049,-0.02,0.11,0.28,0.64,0.28,
-0.11,-0.02,0.049,-0.018,-0.009,0.01,
-0.002,-0.002,0.001,0.0,0.0
};
float fXn[N]={0.0};
float fInput,fOutput;
float fSignal1,fSignal2;
float fStepSignal1,fStepSignal2;
float f2PI;
int i;
float FIN[256],FOUT[256];
int nIn ,nOut;
main(void)
{
nIn=0;nOut=0;
f2PI=2*PI;
fSignal1=0.0;
fSignal2=PI*0.1;
fStepSignal1=2*PI/30;
fStepSignal2=2*PI*1.4;
while(1)
{
// fInput=InputWave();
InputWave();
// FIN[nIn]=fInput;
// nIn++;nIn%=256;
fOutput=FIR();
FOUT[nOut]=fOutput;
nOut++;
if(nOut>=256)
{nOut=0;da0832();
}
}
}
/*float InputWave()
{
for(i=N-1;i>0;i--) fXn[i]=fXn[i-1];
fXn[0]=sin(fSignal1)+cos(fSignal2)/6.0;
fSignal1+=fStepSignal1;
if(fSignal1>=f2PI) fSignal1-=f2PI;
fSignal2+=fStepSignal2;
if(fSignal2>=f2PI) fSignal2-=f2PI;
return(fXn[0]);
} */
void InputWave()
{
int i;
for(i=0;i<=15000;i++)
{
fXn[i]=(sin(PI*2*i/N*15000)+1)*5;
}
}
float FIR()
{
float fSum;
fSum=0;
for(i=0;i<N;i++) fSum+=(fXn[i]*fHn[i]);
return(fSum);
}
void da0832()
{
unsigned char i;
da_cs=0;//da转换输出使能标志置位
da_wr1=0;//输入寄存器的官写选通信号,表示单片机要传送数据了
for (i=0;i<255;i++)
P0=FOUT[i];
da_wr1=1;//数据传送完成,使能锁存
da_cs=1;
}
参考资料:http://wenku.baidu.com/view/ec9d10d149649b6648d7471c.html
MOVX的指令必须要用到P0口的。。(见引用第7页),除非你自己编时序
MOV DPTR,#2FFFH
MOV A,DATA(你要的值,从00-FFH)
MOVX @DPTR,A
参考资料:http://wenku.baidu.com/view/2f2ec36825c52cc58bd6be50.html