Final Project: Sensor Testing

To try and narrow down what we wanted our design to do we tested many different sensors.  Here are some of the codes from the ones that I tested:

PING Ultrasonic Range finder code modified from: http://www.arduino.cc/en/Tutorial/Ping

  

const int pingPin = 7;

void setup() {
  // initialize serial communication:
  Serial.begin(9600);
}

void loop()
{
  // establish variables for duration of the ping,
  // and the distance result in inches and centimeters:
  long duration, inches, cm;

  // 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(5);
  digitalWrite(pingPin, LOW);

  // The same pin is used to read the signal from the PING))): 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.
  pinMode(pingPin, INPUT);
  duration = pulseIn(pingPin, HIGH);

  // convert the time into a distance
  inches = microsecondsToInches(duration);
  cm = microsecondsToCentimeters(duration);
 
  Serial.print(inches);
  Serial.print("in, ");
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
 
  delay(100);
}

long microsecondsToInches(long microseconds)
{

  // See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
  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;
}

 The range finder works well and was put into our final project.


The following sound detector code simply turns an LED on when sound is detected:



int inputPin = 7;
int val = 0;
int ledPin = 13;
void setup() {
  pinMode(inputPin, INPUT);
  pinMode(ledPin, OUTPUT);
}
void loop() {
  val = digitalRead(inputPin);
  if (val == HIGH) {
    digitalWrite (ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW);
  }
}

The sound detector works well for nearby percussive sounds, but does not pick up voices well.  It should work for footsteps on tile floors like the ones in the NCRC where it will be installed, so it will still be used in the final design.