File content as of revision 2:3d4a843be2a9:

#include "mbed.h"
#include "encoder.h"
#include "MODSERIAL.h"

/** keep_in_range -> float in, and keep_in_range if less than min, or larger than max **/
void keep_in_range(float * in, float min, float max);

volatile bool looptimerflag;

void setlooptimerflag(void)
{
    looptimerflag = true;
}


int main() {
    //LOCAL VARIABLES 
    AnalogIn potmeter(PTC2);
    Encoder motor1(PTD0,PTC9);//first pin on PTAx or PTDx
    MODSERIAL pc(USBTX,USBRX);
    PwmOut pwm_motor(PTA12);
    DigitalOut motordir(PTD3);
    float setpoint;
    float pwm_to_motor;
    float setspeed;
    float speed;
    float position2;
    float setpoint2;
    //START OF CODE
    pc.baud(230400);
    Ticker looptimer;
    looptimer.attach(setlooptimerflag,0.01);  
    pc.printf("bla");
    speed = 0; 
    position2 = 0;
    setpoint2 = 0;
    //INFINITE LOOP 
    while(1) {
        while(looptimerflag != true);
        looptimerflag = false;
        setpoint = (potmeter.read()-0.5)*2000;
        setspeed =(setpoint - setpoint2)/0.01;
        speed = (motor1.getPosition() - position2)/0.01;
        pc.printf("s: %f, %d \n\r", setpoint, motor1.getPosition());
        pwm_to_motor = (setpoint - motor1.getPosition())*.0001 + (setspeed - speed)*.00005 ;
        keep_in_range(&pwm_to_motor, -1,1);
        setpoint2 = setpoint;
        position2 = motor1.getPosition();
        if(pwm_to_motor > 0)
            motordir = 1;
        else
            motordir = 0;
        //WRITE VALUE TO MOTOR  
        pwm_motor.write(abs(pwm_to_motor));
    }
}


//coerces value 'in' to min or max when exceeding those values
//if you'd like to understand the statement below take a google for
//'ternary operators'.
void keep_in_range(float * in, float min, float max)
{
    *in > min ? *in < max? : *in = max: *in = min;
}