File content as of revision 0:2ded24549b70:

#include "mbed.h"
#include "HIDScope.h"

// Standaard formule voor het biquad filter
double biquad(double u, double &v1, double &v2, const double a1, const double a2, const double b0, const double b1, const double b2)

{
    double v = u - a1*v1 - a2*v2;
    double y = b0*v + b1*v1 + b2*v2;
    v2=v1;
    v1=v;
    return y;
}
// Filter1 = High pass filter tot 20 Hz

double fh1_v1=0, fh1_v2=0, fh2_v1=0, fh2_v2=0;
const double fh1_a1=-0.84909054461, fh1_a2=0.00000000000, fh1_b0= 1, fh1_b1=-1, fh1_b2=0;
const double fh2_a1=-1.82553264091, fh2_a2=0.85001416809, fh2_b0= 1, fh2_b1=-2, fh2_b2=1;
Ticker FHIGH;
void Highpass_filter()
{
    biquad (u, fh1_v1, fh1_v2, fh1_a1, fh1_a2, fh1_b0, fh1_b1, fh1_b2);
    biquad (u, fh2_v1, fh2_v2, fh2_a1, fh2_a2, fh2_b0, fh2_b1, fh2_b2);
}

// Filter2 = Low pass filter na 60 Hz
double fl1_v1=0, fl1_v2=0, fl2_v1=0, fl2_v2=0;
const double fl1_a1=-0.66979455390, fl1_a2=0.00000000000, fl1_b0= 1, fl1_b1=1, fl1_b2=0;
const double fl2_a1=-1.55376616139, fl2_a2=0.68023470431, fl2_b0= 1, fl2_b1=2, fl2_b2=1;
Ticker FLOW;
void Lowpass_filter()
{
    biquad (u, fl1_v1, fl1_v2, fl1_a1, fl1_a2, fl1_b0, fl1_b1, fl1_b2);
    biquad (u, fl2_v1, fl2_v2, fl2_a1, fl2_a2, fl2_b0, fl2_b1, fl2_b2);
}

// Filter3 = Notch filter at 50 Hz
double fno1_v1=0, fno1_v2=0, fno2_v1=0, fno2_v2=0, fno3_v1=0, fno3_v2=0;
const double fno1_a1 = -1.87934916386, fno1_a2= 0.97731851355, fno1_b0= 1, fno1_b1= -1.90090686046, fno1_b2= 1;
const double fno2_a1 = -1.88341028603, fno2_a2= 0.98825147717, fno2_b0= 1, fno2_b1= -1.90090686046, fno2_b2= 1;
const double fno3_a1 = -1.89635403726, fno3_a2= 0.98894004849, fno3_b0= 1, fno3_b1= -1.90090686046, fno3_b2= 1;
Ticker FNOTCH;
void Notch_filter ()
{
    biquad (u, fno1_v1, fno1_v2, fno1_a1, fno1_a2, fno1_b0, fno1_b1, fno1_b2);
    biquad (u, fno2_v1, fno2_v2, fno2_a1, fno2_a2, fno2_b0, fno2_b1, fno2_b2);
    biquad (u, fno3_v1, fno3_v2, fno3_a1, fno3_a2, fno3_b0, fno3_b1, fno3_b2);
}

int main ()
{
    FHIGH.attach_us(Highpass_filter, 1e4);
    FLOW.attach_us(Lowpass_filter, 1e4);
    FNOTCH.attach_us (Notch_filter, 1e4);
}