QTRAExample.ino

#include <QTRSensors.h>

// This example is designed for use with six analog QTR sensors. These
// reflectance sensors should be connected to analog pins A0 to A5. The
// sensors' emitter control pin (CTRL or LEDON) can optionally be connected to
// digital pin 2, or you can leave it disconnected and remove the call to
// setEmitterPin().
//
// The setup phase of this example calibrates the sensors for ten seconds and
// turns on the Arduino's LED (usually on pin 13) while calibration is going
// on. During this phase, you should expose each reflectance sensor to the
// lightest and darkest readings they will encounter. For example, if you are
// making a line follower, you should slide the sensors across the line during
// the calibration phase so that each sensor can get a reading of how dark the
// line is and how light the ground is. Improper calibration will result in
// poor readings.
//
// The main loop of the example reads the calibrated sensor values and uses
// them to estimate the position of a line. You can test this by taping a piece
// of 3/4" black electrical tape to a piece of white paper and sliding the
// sensor across it. It prints the sensor values to the serial monitor as
// numbers from 0 (maximum reflectance) to 1000 (minimum reflectance) followed
// by the estimated location of the line as a number from 0 to 5000. 1000 means
// the line is directly under sensor 1, 2000 means directly under sensor 2,
// etc. 0 means the line is directly under sensor 0 or was last seen by sensor
// 0 before being lost. 5000 means the line is directly under sensor 5 or was
// last seen by sensor 5 before being lost.

QTRSensors qtr;

const uint8_t SensorCount = 3;
uint16_t sensorValues[SensorCount];

#define LED 2

void setup()
{
  // configure the sensors
  qtr.setTypeAnalog();
  qtr.setSensorPins((const uint8_t[]){36,39,34}, SensorCount);
  //qtr.setEmitterPin(2);

  delay(500);
  pinMode(LED, OUTPUT);
  digitalWrite(LED, HIGH); // turn on Arduino's LED to indicate we are in calibration mode

  // analogRead() takes about 0.1 ms on an AVR.
  // 0.1 ms per sensor * 4 samples per sensor read (default) * 6 sensors
  // * 10 reads per calibrate() call = ~24 ms per calibrate() call.
  // Call calibrate() 400 times to make calibration take about 10 seconds.
  for (uint16_t i = 0; i < 8000; i++)
  {
    qtr.calibrate();
  }
  digitalWrite(LED, LOW); // turn off Arduino's LED to indicate we are through with calibration

  // print the calibration minimum values measured when emitters were on
  Serial.begin(115200);
  for (uint8_t i = 0; i < SensorCount; i++)
  {
    Serial.print(qtr.calibrationOn.minimum[i]);
    Serial.print(' ');
  }
  Serial.println();

  // print the calibration maximum values measured when emitters were on
  for (uint8_t i = 0; i < SensorCount; i++)
  {
    Serial.print(qtr.calibrationOn.maximum[i]);
    Serial.print(' ');
  }
  Serial.println();
  Serial.println();
  delay(1000);
}

void loop()
{
  // read calibrated sensor values and obtain a measure of the line position
  // from 0 to 5000 (for a white line, use readLineWhite() instead)
  uint16_t position = qtr.readLineBlack(sensorValues);

  // print the sensor values as numbers from 0 to 1000, where 0 means maximum
  // reflectance and 1000 means minimum reflectance, followed by the line
  // position
  for (uint8_t i = 0; i < SensorCount; i++)
  {
    Serial.print(sensorValues[i]);
    Serial.print('\t');
  }
  Serial.println(position);

  delay(250);
}