digital audio mod11 / Mbed 2 deprecated fftimplement

oldexamplecode

Dependencies:   mbed

PSDdetection.cpp@0:6863633bf8a4, 2017-03-24 (annotated)

Committer:
rik
Date:
Fri Mar 24 11:22:30 2017 +0000
Revision:
0:6863633bf8a4
oldexamplecode;

Who changed what in which revision?

UserRevisionLine numberNew contents of line
rik 0:6863633bf8a4 1
rik 0:6863633bf8a4 2 #include "PSDdetection.h"
rik 0:6863633bf8a4 3
rik 0:6863633bf8a4 4 Arm::Arm(){
rik 0:6863633bf8a4 5 for (int i = 0; i<4; i++)
rik 0:6863633bf8a4 6 prevEMG[i] = 0;
rik 0:6863633bf8a4 7
rik 0:6863633bf8a4 8 EMGreference = 140;
rik 0:6863633bf8a4 9 }
rik 0:6863633bf8a4 10
rik 0:6863633bf8a4 11 // Sets a new reference level
rik 0:6863633bf8a4 12 void Arm::setReference(int reflevel){
rik 0:6863633bf8a4 13 this->EMGreference = reflevel;
rik 0:6863633bf8a4 14 }
rik 0:6863633bf8a4 15
rik 0:6863633bf8a4 16 // Updates the array with a new sample and checks wheter a muscle is active
rik 0:6863633bf8a4 17 bool Arm::checksample(int emgsample){
rik 0:6863633bf8a4 18
rik 0:6863633bf8a4 19 bool MuscleIsActive = false;
rik 0:6863633bf8a4 20
rik 0:6863633bf8a4 21 // Shift all the previous values in time
rik 0:6863633bf8a4 22 for (int i = 3; i>0; i--){
rik 0:6863633bf8a4 23 prevEMG[i] = prevEMG[i - 1];
rik 0:6863633bf8a4 24 }
rik 0:6863633bf8a4 25
rik 0:6863633bf8a4 26 // Put in the latest sample
rik 0:6863633bf8a4 27 prevEMG[0] = emgsample;
rik 0:6863633bf8a4 28
rik 0:6863633bf8a4 29 // Weighted average filter to smoothen out the response
rik 0:6863633bf8a4 30 int average = (prevEMG[0] * 1 + prevEMG[1] * 0.63 + prevEMG[2] * 0.45 + prevEMG[3] * 0.22) / (1 + 0.63 + 0.45 + 0.22);
rik 0:6863633bf8a4 31
rik 0:6863633bf8a4 32 // Check with reference level to determine if it is
rik 0:6863633bf8a4 33 if (average > (EMGreference + EMGtriggerlevel)){
rik 0:6863633bf8a4 34 MuscleIsActive = true;
rik 0:6863633bf8a4 35 }
rik 0:6863633bf8a4 36
rik 0:6863633bf8a4 37 return MuscleIsActive;
rik 0:6863633bf8a4 38 }
rik 0:6863633bf8a4 39
rik 0:6863633bf8a4 40 int biquad10(int emgsample){
rik 0:6863633bf8a4 41 //initialize filter values
rik 0:6863633bf8a4 42 float filteredValue,a0,a1,a2,b1,b2;
rik 0:6863633bf8a4 43 float intermediateValue1[2]intermediateValue2[2];
rik 0:6863633bf8a4 44 //filter for 10hz -6bd biquad
rik 0:6863633bf8a4 45 a0=0.0009446857782217186;
rik 0:6863633bf8a4 46 a1=0.0018893715564434373;
rik 0:6863633bf8a4 47 a2=0.0009446857782217186;
rik 0:6863633bf8a4 48 b1=-1.9111847961312216;
rik 0:6863633bf8a4 49 b2=0.9149635392441086;
rik 0:6863633bf8a4 50 //calculations for transposed direct form 2
rik 0:6863633bf8a4 51 intermediateValue1[0] = a2*emgsample-b2*filteredValue;
rik 0:6863633bf8a4 52 intermediateValue2[0] = a2*emgsample-b1*filteredValue+intermediateValue1[1];
rik 0:6863633bf8a4 53 filteredValue = a0*filteredValue+intermediateValue2[1];
rik 0:6863633bf8a4 54 intermediateValue1[1] = intermediateValue1[0];
rik 0:6863633bf8a4 55 intermediateValue2[1] = intermediateValue2[0];
rik 0:6863633bf8a4 56
rik 0:6863633bf8a4 57
rik 0:6863633bf8a4 58 return ((int)filteredValue);
rik 0:6863633bf8a4 59 }