File content as of revision 3:61f0fc41f3bc:

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

AnalogIn EMG(A0);
HIDScope scope(4);

// 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;
// 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;
// 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;
double y1, y2, y3, y4, y5, y6, y7, u1, u2, u3, u4, u5, u6, u7;

// 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;
}

void Filters()
{
    u1 = EMG.read();
    //Highpass
    y1 = biquad (u1, fh1_v1, fh1_v2, fh1_a1, fh1_a2, fh1_b0*0.924547, fh1_b1*0.924547, fh1_b2*0.924547);
    u2 = y1;
    y2 = biquad (u2, fh2_v1, fh2_v2, fh2_a1, fh2_a2, fh2_b0*0.918885, fh2_b1*0.918885, fh2_b2*0.918885);
    //Lowpass
    u3 = y2;
    y3 = biquad (u3, fl1_v1, fl1_v2, fl1_a1, fl1_a2, fl1_b0*0.165103, fl1_b1*0.165103, fl1_b2*0.165103);
    u4 = y3;
    y4 = biquad (u4, fl2_v1, fl2_v2, fl2_a1, fl2_a2, fl2_b0*0.031617, fl2_b1*0.031617, fl2_b2*0.031617);
    // Notch
    u5 = y4;
    y5 = biquad (u5, fno1_v1, fno1_v2, fno1_a1, fno1_a2, fno1_b0*1.004206, fno1_b1*1.004206, fno1_b2*1.004206);
    u6 = y5;
    y6 = biquad (u6, fno2_v1, fno2_v2, fno2_a1, fno2_a2, fno2_b0, fno2_b1, fno2_b2);
    u7 = y6;
    y7 = biquad (u7, fno3_v1, fno3_v2, fno3_a1, fno3_a2, fno3_b0*0.973227, fno3_b1*0.973227, fno3_b2*0.973227);
    scope.set (0, u1);
    scope.set (1, y2);
    scope.set (2, y4);
    scope.set (3, y7); 
    scope.send ();
    } 
Ticker filter;
int main ()
{filter.attach_us(Filters,1e3);}