Question from a noob

Aparantly i have to do a normal post first

Hi im a bit new to arduino and its programming langauge, what im trying to do, is for now getting an led to turn on when a certain distance is reached. I am using a parallax ping ultrasonic sensor and on its own works perfectly,

this is the code so far

/* 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

created 3 Nov 2008 by David A. Mellis modified 30 Jun 2009 by Tom Igoe

*/

// this constant won't change. It's the pin number // of the sensor's output: const int pingPin = 7; const int ledPin = 13;

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; }

My question is, is where do i put the "if" statement for having the led turn on and what would like it,

hope this is enough info to go on, and any help much appericiated

My question is, is where do i put the "if" statement for having the led turn on and what would like it,

 Serial.print(inches);
 Serial.print("in, ");
 Serial.print(cm);
 Serial.print("cm");
 Serial.println();

You are printing the values of cm and inches. After printing them would be a good place to use them.

if(inches > 42)
{
   // Turn the LED on
}
else
{
   // Turn the LED off
}

Thanks very much all is working now, ah now the endless possibilities