File content as of revision 0:7c204101adb0:

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

const float PI = 3.14159265359;
const int PULSES_PER_ROTATION = 6533; // Amount of motor encoder pulses per rotation. When using X4 encoding.

Ticker motorTicker; // Ticker function
FastPWM pwmpin1(D5); // SPECIFIC PIN (hoeft niet aangesloten te worden) Tells you how fast the motor has to go (later: pwmpin.write will tell you the duty cycle, aka how much voltage the motor gets)
FastPWM pwmpin2(D6); // SPECIFIC PIN (hoeft niet aangesloten te worden) Tells you how fast the motor has to go (later: pwmpin.write will tell you the duty cycle, aka how much voltage the motor gets)
DigitalOut directionpin1(D4); // SPECIFIC PIN (hoeft niet aangesloten te worden) Direction value (0-1) that the mbed will give the motor: in which direction the motor must rotate
DigitalOut directionpin2(D7); // SPECIFIC PIN (hoeft niet aangesloten te worden) Direction value (0-1) that the mbed will give the motor: in which direction the motor must rotate
AnalogIn potmeter1(A1); // Analoge input van potmeter 1 -> Motor 1
AnalogIn potmeter2(A2); // Analoge input van potmeter 2 -> Motor 2
QEI encoder1(D11, D10, NC, PULSES_PER_ROTATION, QEI::X4_ENCODING); // Reads encoder, connect pins of encoder 1 to D12 and D13; NC: not connected pin (for X4); 6533 prm (counts per rotation)
QEI encoder2(D13, D12, NC, PULSES_PER_ROTATION, QEI::X4_ENCODING); // Reads encoder, connect pins of encoder 2 to D12 and D13; NC: not connected pin (for X4); 6533 prm (counts per rotation)
Serial pc(USBTX, USBRX);

// Updates a motor connected to the specified pins with the given speed.
// The speed can be both positive and negative.
void update_motor(DigitalOut dir, FastPWM pwm, int speed) {
    // either true or false, determines direction (0 or 1)
    dir = speed > 0;
    // pwm duty cycle can only be positive, floating point absolute value (if value is >0, the there still will be a positive value).
    pwm = abs(speed);
}

float encoder_pulses_to_radians(int pulses) {
    return (pulses/(float)PULSES_PER_ROTATION) * 2.0f*PI;
}

// Converts radians/s values into PWM values for motor controll.
// Both positive and negative values.
int radians_per_second_to_pwm(float rps) {
    // With our specific motor, full PWM is equal to 1 round per second.
    // Or 2PI radians per second.
    int pwm_speed = (rps / (2*PI)) * 255;
    if (pwm_speed > 255) { pwm_speed = 255; }
    if (pwm_speed < -255) { pwm_speed = -255; }
    return pwm_speed;
}

// Normalizes a potmeter value from it's original range of [0, 1] to [-1, 1]
float normalize_pot(float pot_value) {
    // scales value potmeter from 0-1 to -1 - 1.
    return pot_value * 2 - 1;
};

double P_controller(double error) {
    double Kp = 10;
    
    // Proportional part:
    double u_k = Kp * error;
    
    return u_k;
}


void motorfunction() {
        // reads out value potmeter 1 between 0-1
        float pot = potmeter2.read();
        float desired_angle = normalize_pot(pot) * PI; // Scale the potmeter to [-PI, PI]
        
        int pulses = encoder2.getPulses();
        float current_angle = encoder_pulses_to_radians(pulses);
        
        float error = current_angle - desired_angle;
        float speed_rps = P_controller(error);
        
        int speed_pwm = radians_per_second_to_pwm(speed_rps);
        
        pc.printf("cur_angle: %f, des_angle: %f, rps: %f, pwm: %i\n", current_angle, desired_angle, speed_rps, speed_pwm);
        
        update_motor(directionpin2, pwmpin2, speed_pwm);
}


int main()
{
    pc.printf("Starting.");
    pwmpin1.period_us(60.0); // 60 microseconds PWM period, 16.7 kHz, defines all PWM pins (only needs to be done once)
    while(true){
        motorfunction();
        wait(0.1);
    } //Lege while loop zodat functie niet afloopt
}