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ImprovedSonicSensor.ino
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ImprovedSonicSensor.ino
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/* 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.
The circuit:
* +V connection of the PING))) attached to +5V
* GND connection of the PING))) attached to ground
* SIG connection of the PING))) attached to digital pin 7
http://www.arduino.cc/en/Tutorial/Ping
created 3 Nov 2008
by David A. Mellis
modified 30 Aug 2011
by Tom Igoe
This example code is in the public domain.
*/
// this constant won't change. It's the pin number
// of the sensor's output:
const int pingPin = A4;
const int trigPin = A5;
const int maxDif = 30;
int last = 75;
void setup() {
// initialize serial communication:
Serial.begin(9600);
//last = microsecondsToInches(pinger());
}
void loop() {
// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;
duration = pinger();
// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);
if((inches - last) < maxDif && (duration - last) > -maxDif){
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();
}
if(inches < 76){
last = inches;
}
/* else{
Serial.print("last: ");
Serial.print(last);
Serial.print("\n");
Serial.print("current: ");
Serial.print(inches);
Serial.print("\n");
}*/
delay(100);
}
long pinger(){
pinMode(trigPin, OUTPUT);
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(5);
digitalWrite(trigPin, 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);
return pulseIn(pingPin, HIGH);
}
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;
}