2023-11-23 Share: ADC（模數轉換）的10種濾波算法

This article is fine for understanding the ADC filter

https://kknews.cc/zh-tw/code/2kl55bz.html#google_vignette

/* A值可根據實際情況調整
value為有效值，new_value為當前採樣值
濾波程序返回有效的實際值 */
#define A 10
char value;
char filter()
{
  char new_value;
  new_value = get_ad();
  if ( ( new_value - value> A ) || ( value - new_value> A )
  return value;
  return new_value;
}

/* N值可根據實際情況調整
排序採用冒泡法*/
#define N 11
char filter()
{
  char value_buf[N];
  char count,i,j,temp;
  for ( count=0;count<N;count++)
  {
    value_buf[count] = get_ad();
    delay();
  }
  for (j=0;j<N-1;j++)
  {
    for (i=0;i<N-j;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];
}

/*
*/
#define N 12
char filter()
{
  int sum = 0;
  for ( count=0;count<N;count++)
  {
    sum + = get_ad();
    delay();
  }
  return (char)(sum/N);
}

/*
*/
#define N 12
char value_buf[N];
char i=0;
char filter()
{
  char count;
  int sum=0;
  value_buf[i++] = get_ad();
  if ( i == N ) i = 0;
  for ( count=0;count<N,count++)
    sum = value_buf[count];
  return (char)(sum/N);
}

/*
*/
#define N 12
char filter()
{
  char count,i,j;
  char value_buf[N];
  int sum=0;
  for (count=0;count<N;count++)
  {
    value_buf[count] = get_ad();
    delay();
  }
  for (j=0;j<N-1;j++)
  {
    for (i=0;i<N-j;i++)
    {
      if ( value_buf>value_buf[i+1] )
      {
        temp = value_buf;
        value_buf = value_buf[i+1];
        value_buf[i+1] = temp;
      }
    }
  }
  for(count=1;count<N-1;count++)
    sum += value[count];
  return (char)(sum/(N-2));
}

略 參考子程序1、3

/* 為加快程序處理速度假定基數為100，a=0~100 */
#define a 50
char value;
char filter()
{
  char new_value;
  new_value = get_ad();
  return (100-a)*value + a*new_value;
}

/* coe數組為加權係數表，存在程序存儲區。*/
#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];
  int sum=0;
  for (count=0,count<N;count++)
  {
    value_buf[count] = get_ad();
    delay();
  }
  for (count=0,count<N;count++)
    sum += value_buf[count]*coe[count];
  return (char)(sum/sum_coe);
}

#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;
}

int BandpassFilter4(int InputAD4)
{
  int ReturnValue;
  int ii;
  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;
  // if (ReturnValue<0)
  // {
  // ReturnValue=-ReturnValue;
  // }
  return ReturnValue;
}

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