File content as of revision 2:3be8cd780b3d:

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

#include "pid.h"

const float PI = 3.14159265359;
const int PULSES_PER_ROTATION = 6533; // Amount of motor encoder pulses per rotation. When using X4 encoding.
const float pid_period = 0.0001; // PID sample period in seconds.

const double Kp = 5.0;
const double Ki = 0.1;
const double Kd = 0.1;

const double motor_threshold_rps = 0.3; // Rad/s under which we send 0 to the motor, to prevent it from jittering around.
const double motor_stall_pwm = 0.5; // PWM fraction above which the motor starts to move.

int printcount = 0;

Ticker pidTicker; // 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);

PID pid(pid_period);

// Updates a motor connected to the specified pins with the given speed.
// The speed can be both positive and negative, in the range [-1, 1].
void update_motor(DigitalOut* dir, FastPWM* pwm, double speed) {
    if (speed < 1.0 && speed > 0) {
        // Speed is in the range [0, 1] but the motor only moves
        // in the range [0.5, 1]. Rescale for this.
        speed = (speed * (1-motor_stall_pwm)) + motor_stall_pwm;
    }
    if (speed > -1.0 && speed < 0) {
        // Speed is in the range [-1, 0] but the motor only moves
        // in the range [-1, -0.5]. Rescale for this.
        speed = (speed * (1-motor_stall_pwm)) - motor_stall_pwm;
    }
    
    // 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 = fabs(speed);
}

double 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.
double radians_per_second_to_pwm(double rps) {
    // If the rad/s is below the anti-jitter treshold, it is simply 0.
    if (rps > 0 && rps < motor_threshold_rps) {
        rps = 0;
    }
    if (rps < 0 && rps > motor_threshold_rps) {
        rps = 0;
    }
    
    
    // With our specific motor, full PWM is equal to 1 round per second.
    // Or 2PI radians per second.
    double pwm_speed = rps / (2*PI);
    
    // PWM speeds can only go between [-1, 1]
    if (pwm_speed > 1) { pwm_speed = 1; }
    if (pwm_speed < -1) { pwm_speed = -1; }
    return pwm_speed;
}

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


void motorfunction() {
        // reads out value potmeter 1 between 0-1
        double pot = potmeter2.read();
        double desired_angle = normalize_pot(pot) * PI; // Scale the potmeter to [-PI, PI]
        
        int pulses = encoder2.getPulses();
        double current_angle = encoder_pulses_to_radians(pulses);
        
        double error = current_angle - desired_angle;
        // PID controll.
        double speed_rps = pid.update(error);
        
        double speed_pwm = radians_per_second_to_pwm(speed_rps);
        
        printcount++;
        if (printcount >= 0.1L/pid_period) {
            pc.printf("c_angle: %f, d_angle: %f, error: %f, rps: %f, speed: %f\n", current_angle, desired_angle, error, speed_rps, speed_pwm);
            printcount = 0;
        }
        
        update_motor(&directionpin2, &pwmpin2, speed_pwm);
}


int main()
{
    pc.baud(115200);
    pc.printf("Starting.");
    pid.set_k_values(Kp, Ki, Kd);
    pidTicker.attach(motorfunction, pid_period);
    pwmpin1.period_us(60.0); // 60 microseconds PWM period, 16.7 kHz, defines all PWM pins (only needs to be done once)
    while(true){
    } //Lege while loop zodat functie niet afloopt
}