File content as of revision 2:3d4fc510f3d5:

#include "mbed.h"
#include "MODSERIAL.h"
#include "QEI.h"
#include "HIDScope.h"

HIDScope scope(2);
PwmOut pwmpin(D5);
DigitalOut directionpin(D4);
AnalogIn potmeter1(A0);
AnalogIn potmeter2(A1);
DigitalIn button(D0);
Ticker Sample;
Timer t;

MODSERIAL pc(USBTX, USBRX);
QEI wheel (D13, D12, NC, 32);

float angle_resolution = (360.0/32.0)*(1.0/131.0);  //degrees/counts 
float samplingfreq = 100.0;        //Hz
float u = 0;
int pulses = 0;
float angle;
float oldangle;
double time_s;
volatile double Kp = 17.5;
volatile double Ki = 1.02;
double refangle;
double error_angle;

double P_controller(double error)
{
    if(button)
    {
        Kp = potmeter2.read()*40;
    }
    else
    {
        Ki = potmeter2.read()*3;
    }
    double u_k = Kp * error;
    
    static double error_integral = 0;
    error_integral = error_integral + error * 1/samplingfreq;
    double u_i = Ki * error_integral;
    return u_k+u_i;
}



float mean(float *samples, int n) {
    float sum = 0.0;
    for (int i=0; i<n; i++) {
        sum += samples[i];
    }
    return sum / (float)n;
}

void sampling()
{
    
}

void changedirection()
{
    directionpin = !directionpin;
}

int main()
{   
    t.start();
    pc.baud(115200);
    pwmpin.period_us(60);
    //button.fall(&changedirection);
    //refvel.attach(&sampling, 1/samplingfreq);
    while (true) {
        pulses = wheel.getPulses();
        refangle = potmeter1.read()*360.0;
        scope.set(0,refangle);
        angle = pulses*angle_resolution; 
        scope.set(1,angle);
        scope.send();
        error_angle = refangle - angle;
        u = P_controller(error_angle)/360.0;
        directionpin = u > 0.0f;      
        pwmpin = fabs(u);
        
        
        pc.printf("Reference velocity is: %f degrees per second \r\n", u);  
        oldangle = angle;  
        wait(1/samplingfreq); 
        
    }
}