File content as of revision 0:4a43061bfa34:

#include "mbed.h"
#include "QTRSensors.h"
#define NUM_SENSORS 7
Serial pc(USBTX, USBRX);

DigitalOut myled(LED1);

// create an object for four QTR-xRC sensors on digital pins 0 and 9, and on analog
// inputs 1 and 3 (which are being used as digital inputs 15 and 17 in this case)

QTRSensorsAnalog qtra((PinName[]) {A5, A4, A3, A2, A1, A0, PA_3}, NUM_SENSORS, 4, D7);
// PA_3, PA_2, PA_10, PB_3, PB_5, PB_4, PB_10

void setup(void);
void readSensors(void);
void readSensorsPlain(void);

int main() {
    pc.printf("Setup!\r\n");
    setup();
    pc.printf("Start Loop!\r\n");
    while(1) {
        pc.printf("Read Sensors!\r\n");
        readSensorsPlain();
    }
}

void setup()
{
  // optional: wait for some input from the user, such as  a button press
 
  // then start calibration phase and move the sensors over both
  // reflectance extremes they will encounter in your application:
  int i;
  for (i = 0; i < 50; i++)  // make the calibration take about 5 seconds
  // originally i < 250
  {
    pc.printf("Calibrate Session %d\r\n",i);
    qtra.calibrate(QTR_EMITTERS_ON);
    wait_ms(20);
  }
  
  for (i = 0; i < NUM_SENSORS; i++)
  {
      pc.printf("Min On %d \r\n", qtra.calibratedMinimumOn[i]);
  }
 
  // optional: signal that the calibration phase is now over and wait for further
  // input from the user, such as a button press
}

void readSensors()
{
  unsigned int sensors[NUM_SENSORS];
  // get calibrated sensor values returned in the sensors array, along with the line position
  // position will range from 0 to 2000, with 1000 corresponding to the line over the middle 
  // sensor.
  int position = qtra.readLine(sensors);
 
  // if all three sensors see very low reflectance, take some appropriate action for this 
  // situation.
  if (sensors[0] > 750 && sensors[1] > 750 && sensors[2] > 750)
  {
    // do something.  Maybe this means we're at the edge of a course or about to fall off 
    // a table, in which case, we might want to stop moving, back up, and turn around.
    pc.printf("do something.  Maybe this means we're at the edge of a course or about to fall off a table, in which case, we might want to stop moving, back up, and turn around.");
    
    //return;
  }
 
  // compute our "error" from the line position.  We will make it so that the error is zero 
  // when the middle sensor is over the line, because this is our goal.  Error will range from
  // -1000 to +1000.  If we have sensor 0 on the left and sensor 2 on the right,  a reading of 
  // -1000 means that we see the line on the left and a reading of +1000 means we see the 
  // line on the right.
  int error = position - 1000;
 
  int leftMotorSpeed = 200;
  int rightMotorSpeed = 200;
  if (error < -500)  // the line is on the left
    leftMotorSpeed = 20;  // turn left
  if (error > 500)  // the line is on the right
    rightMotorSpeed = 20;  // turn right

  pc.printf("Left Motor %d, Right Motor %d\r\n", leftMotorSpeed, rightMotorSpeed);
          myled = 1; // LED is ON
        wait_ms(leftMotorSpeed); // 200 ms
        myled = 0; // LED is OFF
        wait(rightMotorSpeed); // 1 sec

 
  // set motor speeds using the two motor speed variables above
}


void readSensorsPlain()
{
  unsigned int sensors[NUM_SENSORS];
  // get calibrated sensor values returned in the sensors array, along with the line position
  // position will range from 0 to 2000, with 1000 corresponding to the line over the middle 
  // sensor.
  pc.printf("before\r\n");
  qtra.readCalibrated(sensors, QTR_EMITTERS_ON);
  pc.printf("after\r\n");
  
  for (unsigned int i = 0; i < NUM_SENSORS; i++) {
 
      pc.printf("Sensor Value[%d] %d  Min %d    Max %d \r\n", i, sensors[i], qtra.calibratedMinimumOn[i], qtra.calibratedMaximumOn[i]);
    
  } 
  // set motor speeds using the two motor speed variables above
}