File content as of revision 0:30871514c229:

//Works at speed 2.0, KPS 2.0e-2, KD 1.0e-4

//Has tolerance check, Steering doesn't
//Values from Simulation
//#define KPS 0.0896852742245504f
//#define KD 0.072870569295611f
//#define KPS 0.03f

#include "mbed.h"
#include <iostream>

#define TI 0.001f

#define SCALAR 0.6f
#define MINM 0.0f
#define MAXM 1.0f
#define KPM 0.1414f
#define KI 19.7408f

#define KPS 2.0E-2f //Original 2.0e-2
#define KD 1.0e-4f
#define SET 0.0f
#define MINS 0.05f
#define MAXS 0.1f
#define BIAS 0.075f
#define TOL 0.02f
#define STEER_FREQ 0.02f //50 Hz
#define STEERUPDATEPERIOD 0.05

AnalogIn _right(PTB1); //Right sensor
AnalogIn _left(PTB3); //Left sensor
AnalogIn speed(PTB2);   //tachometer

PwmOut servoSig(PTA13); //PWM output to control servo
PwmOut gateDrive(PTA4);

Serial bt(PTE0, PTE1); //COM12
DigitalOut myled(LED_BLUE);

Ticker control;
Timer ctrlTimer;
float data[6];

float Setpoint = 0.0f;
float errSum = 0.0;

float fbPrev = 0.0f;

void serCb()
{
    char x = bt.getc();
    if (x == 'u')
    {
        Setpoint = Setpoint + 0.05;
    }
    else if(x == 'h')
    {
        Setpoint = Setpoint - 0.05;
    }
    else
    {
        bt.putc(x);
    }
    if(Setpoint > MAXM) Setpoint = MAXM;
    if(Setpoint < MINM) Setpoint = MINM;
    bt.printf("%f\r\n", Setpoint);     
}

void stop()
{
  Setpoint = 0.0f;  
}

void steer()
{
    float L = _left.read();
    float R = _right.read();
    if(L == 0.0f && R == 0.0f)
    {
        stop();
    }    
    float fb = L - R; 
    float e = SET - fb;
    float Controlleroutput = KPS * e - (KD * (fb - fbPrev)/TI)+ BIAS;//subtract derivative of error?? 
    if (Controlleroutput > MAXS) Controlleroutput = MAXS;
    else if (Controlleroutput < MINS) Controlleroutput = MINS;
    if (abs(Controlleroutput - servoSig.read()) > TOL || ctrlTimer.read() >= STEERUPDATEPERIOD) 
    {
        ctrlTimer.reset();
        servoSig.write(Controlleroutput);
    }
    fbPrev = fb;
    data[0] = _right.read();
    data[1] = _left.read();
    data[2] = Controlleroutput;
    data[3] = e;
    
}
void drive()
{
    float error = Setpoint-speed.read();
    errSum +=(error * TI);
    float iTerm = KI*errSum;
    if(iTerm > MAXM) iTerm = MAXM;
    if(iTerm < MINM) iTerm = MINM; 
    float output = KPM*error + iTerm;
    if(output > MAXM) output = MAXM;
    if(output < MINM) output = MINM;    
    if(output < MINM) 
    {
        gateDrive.write(MINM);
        //brake.write(1);
    }
    else 
    {
        //brake.write(0);
        gateDrive.write(output);
    }     
    data[4] = gateDrive.read();
    data[5] = speed.read(); 
}

void cb()
{
    steer();
    drive();
}

int main()
{   
    //startup checks
    bt.attach(&serCb);
    servoSig.period(STEER_FREQ);
    gateDrive.period(.00005f);
    gateDrive.write(Setpoint);

    ctrlTimer.start();
    control.attach(&cb, TI);
    
    bt.baud(115200);
    bt.printf("Right Left SteerControl SteerError GateDrive Speed\r\n");
    while(1) {
        myled = !myled;
        bt.printf("%f ",data[0]);
        bt.printf("%f ", data[1]);
        bt.printf("%f ", data[2]);
        bt.printf("%f ", data[3]);
        bt.printf("%f ", data[4]);
        bt.printf("%f\r\n", data[5]);
    }
}