Matthew Thewsey
/
ELEC347_Coursework_NonVariable
Non-variable (TESTEDandWORKING)
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Diff: Filter.cpp
- Revision:
- 0:d39a06ca6bf1
- Child:
- 1:b088b771a591
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/Filter.cpp Thu Nov 23 10:41:18 2017 +0000 @@ -0,0 +1,71 @@ +#include "Filter.hpp" + +FILTER::FILTER(int Fs, int Fo, int Boost, int Q) //Constuctor +{ + _Fs = Fs; + this-> _Fo = Fo; + this-> _Boost = Boost; + this-> _Q = Q; + + // B - Upnominator coefficients + _b0 = 0.0201; + _b1 = 0.0; + _b2 = -0.0402; + _b3 = 0.0; + _b4 = 0.0201; + + // A - Denominator coefficients + _a0 = 1.0000; + _a1 = -2.5494; + _a2 = 3.2024; + _a3 = -2.0359; + _a4 = 0.6414; + + _centreTap = 1; + _G = 0; + _k = 0; + _Wo = 0; + + _xn = 0; //this value is the input value + _xnm1 = 0; + _xnm2 = 0; + _xnm3 = 0; + _xnm4 = 0; + + _yn = 0; + _ynm1 = 0; + _ynm2 = 0; + _ynm3 = 0; + _ynm4 = 0; +} + +FILTER::~FILTER() {} + +void FILTER::setvalue(int RAW_input) +{ + + _xn = RAW_input; + _centreTap = _xn*_b0 + _xnm1*_b1 + _xnm2*_b2 + _xnm3*_b3 + _xnm4*_b4; //IIR Filter + _yn = _centreTap*_a0 - _a1*_ynm1 - _a2*_ynm2 - _a3*_ynm3 - _a4*_ynm4; //Result in yn + + FilterOutput=_yn+0.5f; //Output resultant to DAC. Again MBED uses 0.0 to 1.0 float!!!!!! and Offset to give 0 to 3V3 range + + //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL xnm VALUES WILL BECOME THE SAME AS xn + _xnm4 = _xnm3; + _xnm3 = _xnm2; + _xnm2 = _xnm1; + _xnm1 = _xn; + + //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL ynm VALUES WILL BECOME THE SAME AS yn + _ynm4 = _ynm3; + _ynm3 = _ynm2; + _ynm2 = _ynm1; + _ynm1 = _yn; + +} + +float FILTER::getvalue(void) +{ + return FilterOutput; +} +