假定從8位AD中讀取數(shù)據(jù)（如果是更高位的AD可定義數(shù)據(jù)類(lèi)型為int),子程序?yàn)間et_ad();

1、限副濾波

#define A 10

char value;

char filter()
{
charnew_value;
new_value = get_ad();
if ( ( new_value - value> A ) || ( value - new_value> A )
return value;
return new_value;

}

2、中位值濾波法

#define N11

char filter()
{
char value_buf[N];
char count,i,j,temp;
for ( count=0;count{
value_buf[count] = get_ad();
delay();
}
for (j=0;j{
for (i=0;i{
if ( value_buf>value_buf[i+1] )
{
temp = value_buf;
value_buf = value_buf[i+1];
value_buf[i+1] = temp;
}
}
}
return value_buf[(N-1)/2];
}

3、算術(shù)平均濾波法


#define N 12

char filter()
{
intsum = 0;
for ( count=0;count{
sum + = get_ad();
delay();
}
return (char)(sum/N);
}

4、遞推平均濾波法（又稱(chēng)滑動(dòng)平均濾波法）

#define N 12

char value_buf[N];
char i=0;

char filter()
{
char count;
intsum=0;
value_buf[i++] = get_ad();
if ( i == N )i = 0;
for ( count=0;countsum = value_buf[count];
return (char)(sum/N);
}

5、中位值平均濾波法（又稱(chēng)防脈沖干擾平均濾波法）

#define N 12

char filter()
{
char count,i,j;
char value_buf[N];
intsum=0;
for(count=0;count{
value_buf[count] = get_ad();
delay();
}
for (j=0;j{
for (i=0;i{
if ( value_buf[i]>value_buf[i+1] )
{
temp = value_buf[i];
value_buf[i] = value_buf[i+1];
value_buf[i+1] = temp;
}
}
}
for(count=1;countsum += value[count];
return (char)(sum/(N-2));
}

6、限幅平均濾波法

略 參考子程序1、3

7、一階滯后濾波法


#define a 50

char value;

char filter()
{
charnew_value;
new_value = get_ad();
return (100-a)*value + a*new_value;
}

8、加權(quán)遞推平均濾波法


#define N 12

char code coe[N] = {1,2,3,4,5,6,7,8,9,10,11,12};
char code sum_coe = 1+2+3+4+5+6+7+8+9+10+11+12;

char filter()
{
char count;
char value_buf[N];
intsum=0;
for (count=0,count{
value_buf[count] = get_ad();
delay();
}
for (count=0,countsum += value_buf[count]*coe[count];
return (char)(sum/sum_coe);
}

9、消抖濾波法

#define N 12

char filter()
{
char count=0;
char new_value;
new_value = get_ad();
while (value !=new_value);
{
count++;
if (count>=N)return new_value;
delay();
new_value = get_ad();
}
return value;
}

10、限幅消抖濾波法

略 參考子程序1、9

11、IIR濾波例子

intBandpassFilter4(int InputAD4)
{
intReturnValue;
intii;
RESLO=0;
RESHI=0;
MACS=*PdelIn;
OP2=1068; //FilterCoeff4[4];
MACS=*(PdelIn+1);
OP2=8;//FilterCoeff4[3];
MACS=*(PdelIn+2);
OP2=-2001;//FilterCoeff4[2];
MACS=*(PdelIn+3);
OP2=8;//FilterCoeff4[1];
MACS=InputAD4;
OP2=1068; //FilterCoeff4[0];
MACS=*PdelOu;
OP2=-7190;//FilterCoeff4[8];
MACS=*(PdelOu+1);
OP2=-1973; //FilterCoeff4[7];
MACS=*(PdelOu+2);
OP2=-19578;//FilterCoeff4[6];
MACS=*(PdelOu+3);
OP2=-3047; //FilterCoeff4[5];
*p=RESLO;
*(p+1)=RESHI;
mytestmul<<=2;
ReturnValue=*(p+1);
for(ii=0;ii<3;ii++)
{
DelayInput[ii]=DelayInput[ii+1];
DelayOutput[ii]=DelayOutput[ii+1];
}
DelayInput[3]=InputAD4;
DelayOutput[3]=ReturnValue;


return ReturnValue;
}