| /* 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 = 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) |
| { |
| // 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; |
| } |