src/include/LowPassFilter.h

   1 #pragma once
   2 #include "stdint.h"
   3
   4 /////////// Super Simple Fixed Point Lowpass ////////////////
   5
   6 class LPF
   7 {
   8 public:
   9     int32_t SmoothDataINT;
  10     int32_t SmoothDataFP;
  11     int32_t Beta = 3;     // Length = 16
  12     int32_t FP_Shift = 5; //Number of fractional bits
  13     bool NeedReset = true;  // wait for the first data to upcoming.
  14
  15     LPF(int Beta_, int FP_Shift_)
  16     {
  17         Beta = Beta_;
  18         FP_Shift = FP_Shift_;
  19     }
  20
  21     LPF(int Beta_)
  22     {
  23         Beta = Beta_;
  24     }
  25
  26     LPF()
  27     {
  28         Beta = 3;
  29         FP_Shift = 5;
  30     }
  31
  32     int32_t ICACHE_RAM_ATTR update(int32_t Indata)
  33     {
  34         if (NeedReset)
  35         {
  36             init(Indata);
  37             return SmoothDataINT;
  38         }
  39
  40         int RawData;
  41         RawData = Indata;
  42         RawData <<= FP_Shift; // Shift to fixed point
  43         SmoothDataFP = (SmoothDataFP << Beta) - SmoothDataFP;
  44         SmoothDataFP += RawData;
  45         SmoothDataFP >>= Beta;
  46         // Don't do the following shift if you want to do further
  47         // calculations in fixed-point using SmoothData
  48         SmoothDataINT = SmoothDataFP >> FP_Shift;
  49         return SmoothDataINT;
  50     }
  51
  52     void ICACHE_RAM_ATTR reset()
  53     {
  54         NeedReset = true;
  55     }
  56
  57
  58     void ICACHE_RAM_ATTR init(int32_t Indata)
  59     {
  60         NeedReset = false;
  61
  62         SmoothDataINT = Indata;
  63         SmoothDataFP = SmoothDataINT << FP_Shift;
  64     }
  65
  66     int32_t value() const { return SmoothDataINT; }
  67 };