Sensor Technology Tasks

Triggering and modulating events

Real-life examples of triggering and modulating events.

• The digiphone
  • Ultrasound
  • What to do about moving out of range (averaging)?
  • Proximity or movement?
  • buttons (scenes)
  • (INScore)
  
  
• Threads (mBed)
  • ribbons or threads
  • on/off or sliding scale (interrupts or not)
  • triggering, but not too much
  • using continuous values
  • what sound?
  
  
• Using 'scenes'
  • fixed or changing structures
  • scenes

A real life example

Ultrasound Ping Code for Arduino

// Gagglina v01
// 110301
// Based on GaggleSingle v003
// Now works via one routine
// just the one ping, for testing...

int myDel = 5;

void setup()
{
  Serial.begin(115200);
}

void loop()
{
  ping(2);
//  ping(3);
//  ping(4);
//  ping(5);
//  ping(6);
//  ping(7);
//  ping(8);
//  ping(9);
//  ping(10);
}


void ping(int pingPin)
{
  long duration;
  float cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // We 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);
  
  Serial.print(pingPin);
  Serial.print(", ");
  Serial.println(duration);
 //  Serial.print(", ");
  // Serial.println(myDel);
  
  // convert the time into a distance
  /*
  cm = microsecondsToCentimeters(duration);

  Serial.print("a: "); 
  Serial.print(cm);
  Serial.print("cm");
  Serial.println();
  */
  
  // control the rate via a pingPin
  // these need ranging, so there's are ranges of difference between one 'range' and another.
  // if (pingPin == 8) { myDel = map(duration, 0, 15000, 500, 20) ; }
  
  delay(myDel);
}

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.
  // 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;
}

Here is a working Max patch: http://rhoadley.org/courses/tech_resources/stech/tasks/triggers/triggering.zip