CMST / Mbed 2 deprecated ELEC347_Coursework

V001. 2017_11_30 10:21 Working code from Tuesday's lab session.

Dependencies:   mbed-rtos mbed

Fork of 2017_11_28_ELEC347_Coursework by Chris Hills

DSP Coursework ELEC347 2017-2018 Group members: Matthew Thewsey, Thomas Morris, Samuel Waggett, Christopher Hills .

Filter.cpp@18:b442994a01fd, 2017-12-06 (annotated)

Committer:
chills
Date:
Wed Dec 06 02:44:44 2017 +0000
Revision:
18:b442994a01fd
Parent:
13:db76473a3d76 
Task 4.2 Cut Filter Implementation

Who changed what in which revision?

UserRevisionLine numberNew contents of line
chills 6:a2737b51424c 1 #include "mbed.h"
mwthewsey 0:d39a06ca6bf1 2 #include "Filter.hpp"
mwthewsey 2:f6e49378dd8a 3 #include <math.h>
mwthewsey 0:d39a06ca6bf1 4
chills 6:a2737b51424c 5
mwthewsey 2:f6e49378dd8a 6 #define PI 3.14159
mwthewsey 2:f6e49378dd8a 7
mwthewsey 2:f6e49378dd8a 8 FILTER::FILTER(int Fs, int Fo, double Boost, int Q) //Constuctor
mwthewsey 0:d39a06ca6bf1 9 {
thomasmorris 11:7efb6e4759cc 10 //Storing Paremeters into the Class
mwthewsey 2:f6e49378dd8a 11 this-> _Fs = Fs;
mwthewsey 0:d39a06ca6bf1 12 this-> _Fo = Fo;
mwthewsey 0:d39a06ca6bf1 13 this-> _Boost = Boost;
mwthewsey 0:d39a06ca6bf1 14 this-> _Q = Q;
thomasmorris 11:7efb6e4759cc 15
thomasmorris 11:7efb6e4759cc 16 //Initializing Variables
thomasmorris 11:7efb6e4759cc 17
mwthewsey 0:d39a06ca6bf1 18 _centreTap = 1;
mwthewsey 0:d39a06ca6bf1 19 _G = 0;
mwthewsey 0:d39a06ca6bf1 20 _k = 0;
mwthewsey 0:d39a06ca6bf1 21 _Wo = 0;
mwthewsey 2:f6e49378dd8a 22 _Wo_d = 0;
mwthewsey 2:f6e49378dd8a 23 _Wo_d2 = 0;
mwthewsey 2:f6e49378dd8a 24 _Com_Den = 0;
mwthewsey 2:f6e49378dd8a 25 _NC0 = 0;
mwthewsey 2:f6e49378dd8a 26 _NC1 = 0;
mwthewsey 2:f6e49378dd8a 27 _NC2 = 0;
mwthewsey 2:f6e49378dd8a 28 _DC1 = 0;
mwthewsey 2:f6e49378dd8a 29 _DC2 = 0;
mwthewsey 0:d39a06ca6bf1 30
mwthewsey 2:f6e49378dd8a 31 _xn = 0; //This value is the input value
mwthewsey 0:d39a06ca6bf1 32 _xnm1 = 0;
mwthewsey 0:d39a06ca6bf1 33 _xnm2 = 0;
mwthewsey 0:d39a06ca6bf1 34
mwthewsey 0:d39a06ca6bf1 35 _yn = 0;
mwthewsey 0:d39a06ca6bf1 36 _ynm1 = 0;
mwthewsey 0:d39a06ca6bf1 37 _ynm2 = 0;
mwthewsey 0:d39a06ca6bf1 38 }
mwthewsey 0:d39a06ca6bf1 39
thomasmorris 11:7efb6e4759cc 40 FILTER::~FILTER()//Destructor
thomasmorris 11:7efb6e4759cc 41 {
thomasmorris 11:7efb6e4759cc 42
thomasmorris 11:7efb6e4759cc 43 }
mwthewsey 0:d39a06ca6bf1 44
thomasmorris 11:7efb6e4759cc 45 void FILTER::setvalue(float RAW_input)//Sets the raw input value to the class
thomasmorris 11:7efb6e4759cc 46 {
mwthewsey 0:d39a06ca6bf1 47 _xn = RAW_input;
mwthewsey 2:f6e49378dd8a 48 _centreTap = _xn*_b0 + _xnm1*_b1 + _xnm2*_b2; //IIR Filter
mwthewsey 2:f6e49378dd8a 49 _yn = _centreTap*_a0 - _a1*_ynm1 - _a2*_ynm2; //Result in yn
mwthewsey 0:d39a06ca6bf1 50
mwthewsey 2:f6e49378dd8a 51 _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
mwthewsey 0:d39a06ca6bf1 52
mwthewsey 0:d39a06ca6bf1 53 //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL xnm VALUES WILL BECOME THE SAME AS xn
mwthewsey 0:d39a06ca6bf1 54 _xnm2 = _xnm1;
mwthewsey 0:d39a06ca6bf1 55 _xnm1 = _xn;
mwthewsey 0:d39a06ca6bf1 56
mwthewsey 0:d39a06ca6bf1 57 //THESE NEED TO BE LOADED IN THIS ORDER OTHERWISE ALL ynm VALUES WILL BECOME THE SAME AS yn
mwthewsey 0:d39a06ca6bf1 58 _ynm2 = _ynm1;
mwthewsey 0:d39a06ca6bf1 59 _ynm1 = _yn;
mwthewsey 0:d39a06ca6bf1 60 }
mwthewsey 0:d39a06ca6bf1 61
thomasmorris 11:7efb6e4759cc 62 float FILTER::getvalue(void)//Returns the current filter output value
mwthewsey 0:d39a06ca6bf1 63 {
mwthewsey 2:f6e49378dd8a 64 return _FilterOutput;
mwthewsey 0:d39a06ca6bf1 65 }
mwthewsey 0:d39a06ca6bf1 66
mwthewsey 2:f6e49378dd8a 67 void FILTER::Define_Filter()//Define the filter coefficients
mwthewsey 2:f6e49378dd8a 68 {
thomasmorris 11:7efb6e4759cc 69 //Calculate the values for the equation parameters
mwthewsey 2:f6e49378dd8a 70 _G = pow(10,_Boost/20.0);
mwthewsey 2:f6e49378dd8a 71 _k = 3 * ((_G - 1) / (_G+1));
mwthewsey 2:f6e49378dd8a 72 _Wo = 2 * PI * _Fo;
mwthewsey 2:f6e49378dd8a 73 _Wo_d = tan(_Wo / (2*_Fs));
thomasmorris 11:7efb6e4759cc 74 _Wo_d2 = (_Wo_d * _Wo_d);//Omega-Dash-Naught-Squared
mwthewsey 2:f6e49378dd8a 75 _Com_Den = 1 + ((3-_k)*_Wo_d/_Q) + _Wo_d2;
mwthewsey 2:f6e49378dd8a 76 _NC0 = 1 + ((3+_k)*_Wo_d/_Q) + _Wo_d2;
mwthewsey 2:f6e49378dd8a 77 _NC1 = -2 + (2 * _Wo_d2);
mwthewsey 2:f6e49378dd8a 78 _NC2 = 1 - ((3+_k)*_Wo_d/_Q) + _Wo_d2;
mwthewsey 2:f6e49378dd8a 79 _DC1 = _NC1;
mwthewsey 2:f6e49378dd8a 80 _DC2 = 1 - ((3-_k)*_Wo_d/_Q) + _Wo_d2;
mwthewsey 2:f6e49378dd8a 81
mwthewsey 2:f6e49378dd8a 82 //Calculate Coefficients
mwthewsey 2:f6e49378dd8a 83
mwthewsey 2:f6e49378dd8a 84 _b0 = _NC0 / _Com_Den;
mwthewsey 2:f6e49378dd8a 85 _b1 = _NC1 / _Com_Den;
mwthewsey 2:f6e49378dd8a 86 _b2 = _NC2 / _Com_Den;
mwthewsey 2:f6e49378dd8a 87 _a0 = 1.0000;
mwthewsey 2:f6e49378dd8a 88 _a1 = _DC1 / _Com_Den;
mwthewsey 2:f6e49378dd8a 89 _a2 = _DC2 / _Com_Den;
mwthewsey 2:f6e49378dd8a 90 }
mwthewsey 2:f6e49378dd8a 91
thomasmorris 11:7efb6e4759cc 92 void FILTER::Print_Filter()//Print Filter Coefficients
chills 6:a2737b51424c 93 {
chills 8:192b376a6da7 94 printf("Num 1 = %f\t", _b0);
chills 8:192b376a6da7 95 printf("Num 2 = %f\t", _b1);
chills 8:192b376a6da7 96 printf("Num 3 = %f\t", _b2);
chills 8:192b376a6da7 97 printf("Den 1 = %f\t", _a0);
chills 8:192b376a6da7 98 printf("Den 2 = %f\t", _a1);
chills 6:a2737b51424c 99 printf("Den 3 = %f\n\r", _a2);
chills 7:6cb27cce4c50 100 }
thomasmorris 13:db76473a3d76 101 void FILTER::coeff_update(float _Fo_Current,float _Boost_Current,float _Q_Current)
thomasmorris 13:db76473a3d76 102 {
thomasmorris 13:db76473a3d76 103
thomasmorris 13:db76473a3d76 104
thomasmorris 13:db76473a3d76 105 if (abs(_Fo_Current - _Fo) > 50) //If Centre Frequency has changed significantly
thomasmorris 13:db76473a3d76 106 {
thomasmorris 13:db76473a3d76 107 _Fo = _Fo_Current;
thomasmorris 13:db76473a3d76 108 }
thomasmorris 13:db76473a3d76 109 if (abs(_Boost_Current - _Boost) > 2) //If Boost has changed significantly
thomasmorris 13:db76473a3d76 110 {
thomasmorris 13:db76473a3d76 111 _Boost = _Boost_Current;
thomasmorris 13:db76473a3d76 112 }
thomasmorris 13:db76473a3d76 113 if (abs(_Q_Current - _Q) > 2) //If Q has changed significantly
thomasmorris 13:db76473a3d76 114 {
thomasmorris 13:db76473a3d76 115 _Q = _Q_Current;
thomasmorris 13:db76473a3d76 116 }
thomasmorris 13:db76473a3d76 117
thomasmorris 13:db76473a3d76 118 Define_Filter();
thomasmorris 13:db76473a3d76 119 }
chills 7:6cb27cce4c50 120
chills 7:6cb27cce4c50 121 void FILTER::Update_Fo(int Fo_New){_Fo = Fo_New;}
chills 7:6cb27cce4c50 122 int FILTER::Get_Fo(){return _Fo;}
chills 7:6cb27cce4c50 123
chills 7:6cb27cce4c50 124 void FILTER::Update_Q(int Q_New){_Q = Q_New;}
chills 7:6cb27cce4c50 125 int FILTER::Get_Q(){return _Q;}
chills 7:6cb27cce4c50 126
chills 7:6cb27cce4c50 127 void FILTER::Update_Boost(double Boost_New){_Boost = Boost_New;}
chills 7:6cb27cce4c50 128 double FILTER::Get_Boost(){return _Boost;}