#include LiquidCrystal lcd(12, 11, 5, 4, 3, 2); int pingPin = 9; int inPin = 8; void setup() { lcd.begin(16, 2); lcd.print("testing..."); } 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(10); 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(inPin, INPUT); duration = pulseIn(inPin, HIGH); // convert the time into a distance inches = microsecondsToInches(duration); cm = microsecondsToCentimeters(duration); lcd.clear(); lcd.setCursor(0, 0); lcd.print(inches); lcd.print("in, "); lcd.print(cm); lcd.print("cm"); 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. 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; }