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83 lines
2.5 KiB
Plaintext
83 lines
2.5 KiB
Plaintext
/* Ping))) Sensor
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This sketch reads a PING))) ultrasonic rangefinder and returns the
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distance to the closest object in range. To do this, it sends a pulse
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to the sensor to initiate a reading, then listens for a pulse
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to return. The length of the returning pulse is proportional to
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the distance of the object from the sensor.
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The circuit:
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* +V connection of the PING))) attached to +5V
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* GND connection of the PING))) attached to ground
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* SIG connection of the PING))) attached to digital pin 7
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http://www.arduino.cc/en/Tutorial/Ping
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created 3 Nov 2008
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by David A. Mellis
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modified 30 Jun 2009
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by Tom Igoe
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*/
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// this constant won't change. It's the pin number
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// of the sensor's output:
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const int pingPin = 7;
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void setup() {
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// initialize serial communication:
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Serial.begin(9600);
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}
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void loop()
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{
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// establish variables for duration of the ping,
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// and the distance result in inches and centimeters:
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long duration, inches, cm;
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// The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
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// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
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pinMode(pingPin, OUTPUT);
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digitalWrite(pingPin, LOW);
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delayMicroseconds(2);
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digitalWrite(pingPin, HIGH);
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delayMicroseconds(5);
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digitalWrite(pingPin, LOW);
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// The same pin is used to read the signal from the PING))): a HIGH
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// pulse whose duration is the time (in microseconds) from the sending
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// of the ping to the reception of its echo off of an object.
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pinMode(pingPin, INPUT);
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duration = pulseIn(pingPin, HIGH);
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// convert the time into a distance
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inches = microsecondsToInches(duration);
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cm = microsecondsToCentimeters(duration);
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Serial.print(inches);
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Serial.print("in, ");
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Serial.print(cm);
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Serial.print("cm");
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Serial.println();
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delay(100);
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}
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long microsecondsToInches(long microseconds)
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{
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// According to Parallax's datasheet for the PING))), there are
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// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
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// second). This gives the distance travelled by the ping, outbound
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// and return, so we divide by 2 to get the distance of the obstacle.
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// See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
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return microseconds / 74 / 2;
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}
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long microsecondsToCentimeters(long microseconds)
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{
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// The speed of sound is 340 m/s or 29 microseconds per centimeter.
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// The ping travels out and back, so to find the distance of the
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// object we take half of the distance travelled.
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return microseconds / 29 / 2;
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}
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