/elec/quadcopter

/* Ping))) Sensor

   This sketch reads a PING))) ultrasonic rangefinder and returns the

   distance to the closest object in range. To do this, it sends a pulse

   to the sensor to initiate a reading, then listens for a pulse

   to return.  The length of the returning pulse is proportional to

   the distance of the object from the sensor.

   based on the original code from the tutorial at:

   http://www.arduino.cc/en/Tutorial/Ping

   This example code is in the public domain.

 */

int pingPin = 13;

int inPin = 12;

long duration, inches, cm;

void setup() {

  //pinMode(13, OUTPUT);

  pinMode(pingPin, OUTPUT);

  pinMode(inPin, INPUT);

  Serial.begin(9600);

}

long microsecondsToInches(long microseconds)

{

  // According to Parallax's datasheet for the PING))), there are

  // 73.746 microseconds per inch (i.e. sound travels at 1130 feet per

  // second).  This gives the distance travelled by the ping, outbound

  // and return, so we divide by 2 to get the distance of the obstacle.

  return microseconds / 74 / 2;

}

long microsecondsToCentimeters(long microseconds)

{

  // The speed of sound is 340 m/s or 29 microseconds per centimeter.

  // The ping travels out and back, so to find the distance of the

  // object we take half of the distance travelled.

  return microseconds / 29 / 2;

}

void loop()

{

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.

  // Give a short LOW pulse beforehand to ensure a clean HIGH pulse:

  //pinMode(pingPin, OUTPUT);

  digitalWrite(pingPin, LOW);

  delayMicroseconds(2);

  digitalWrite(pingPin, HIGH);

  delayMicroseconds(10);

  digitalWrite(pingPin, LOW);

  //delayMicroseconds(2);

  // a HIGH

  // pulse whose duration is the time (in microseconds) from the sending

  // of the ping to the reception of its echo off of an object.

  duration = pulseIn(inPin, HIGH);

  // convert the time into a distance

  inches = microsecondsToInches(duration);

  cm = microsecondsToCentimeters(duration);

  Serial.print("Distance: [");

  Serial.print(inches);

  Serial.print("]inches. [");

  Serial.print(cm);

  Serial.print("]cm\r\n");

  delay(50);

}